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Sample records for doubly-fed induction generators

  1. Doubly-Fed Induction Generator Control Under Voltage Sags

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Lima, K.

    2008-01-01

    This paper proposes a new control technique to improve the fault-ride through capability of doubly fed induction generators (DFIG). In such generators the appearance of severe voltage sags at the coupling point make rise to high over currents at the rotor/stator windings, something that makes...

  2. Crowbar System in Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    Maurício B. C. Salles

    2010-04-01

    Full Text Available In the last 15 years, the use of doubly fed induction machines in modern variable-speed wind turbines has increased rapidly. This development has been driven by the cost reduction as well as the low-loss generation of Insulated Gate Bipolar Transistors (IGBT. According to new grid code requirements, wind turbines must remain connected to the grid during grid disturbances. Moreover, they must also contribute to voltage support during and after grid faults. The crowbar system is essential to avoid the disconnection of the doubly fed induction wind generators from the network during faults. The insertion of the crowbar in the rotor circuits for a short period of time enables a more efficient terminal voltage control. As a general rule, the activation and the deactivation of the crowbar system is based only on the DC-link voltage level of the back-to-back converters. In this context, the authors discuss the critical rotor speed to analyze the instability of doubly fed induction generators during grid faults.

  3. Robust Adaptive Reactive Power Control for Doubly Fed Induction Generator

    Directory of Open Access Journals (Sweden)

    Huabin Wen

    2014-01-01

    Full Text Available The problem of reactive power control for mains-side inverter (MSI in doubly fed induction generator (DFIG is studied in this paper. To accommodate the modelling nonlinearities and inherent uncertainties, a novel robust adaptive control algorithm for MSI is proposed by utilizing Lyapunov theory that ensures asymptotic stability of the system under unpredictable external disturbances and significant parametric uncertainties. The distinguishing benefit of the aforementioned scheme consists in its capabilities to maintain satisfactory performance under varying operation conditions without the need for manually redesigning or reprogramming the control gains in contrast to the commonly used PI/PID control. Simulations are also built to confirm the correctness and benefits of the control scheme.

  4. Loss Minimizing Operation of Doubly Fed Induction Generator Based Wind Generation Systems Considering Reactive Power Provision

    DEFF Research Database (Denmark)

    Baohua, Zhang; Hu, Weihao; Chen, Zhe

    2014-01-01

    The paper deals with control techniques for minimizing the operating loss of doubly fed induction generator based wind generation systems when providing reactive power. The proposed method achieves its goal through controlling the rotor side q-axis current in the synchronous reference frame...

  5. Neural network based control of Doubly Fed Induction Generator in wind power generation

    Science.gov (United States)

    Barbade, Swati A.; Kasliwal, Prabha

    2012-07-01

    To complement the other types of pollution-free generation wind energy is a viable option. Previously wind turbines were operated at constant speed. The evolution of technology related to wind systems industry leaded to the development of a generation of variable speed wind turbines that present many advantages compared to the fixed speed wind turbines. In this paper the phasor model of DFIG is used. This paper presents a study of a doubly fed induction generator driven by a wind turbine connected to the grid, and controlled by artificial neural network ANN controller. The behaviour of the system is shown with PI control, and then as controlled by ANN. The effectiveness of the artificial neural network controller is compared to that of a PI controller. The SIMULINK/MATLAB simulation for Doubly Fed Induction Generator and corresponding results and waveforms are displayed.

  6. Model and performance of current sensor observers for a doubly fed induction generator

    DEFF Research Database (Denmark)

    Li, Hui; Yang, Chao; Hu, Yaogang

    2014-01-01

    . A stator and rotor current observer model, which is based on the state-space models of doubly fed induction generators, is then derived by using the stator and rotor voltage signals as inputs. To demonstrate the effectiveness of the proposed current observer, its dynamic performance is simulated using...

  7. Thermal Behavior of Doubly-Fed Induction Generator Wind Turbine System during Balanced Grid Fault

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2014-01-01

    Ride-through capabilities of the doubly-fed induction generator (DFIG) during grid fault have been studied a lot. However, the thermal performance of the power device during this transient period is seldom investigated. In this paper, the dynamic model for the DFIG and the influence of the rotor...

  8. Rotor Voltage Dynamics in the Doubly Fed Induction Generator During Grid Faults

    DEFF Research Database (Denmark)

    Lima, Francisco K. A.; Luna, Alvaro; Rodriguez, Pedro

    2010-01-01

    This paper presents a new control strategy for the rotor-side converter (RSC) of wind turbines (WTs) based on doubly fed induction generators (DFIG) that intends to improve its low-voltage ride through capability. The main objective of this work is to design an algorithm that would enable the sys...

  9. IQC-based robust stability analysis for LPV control of doubly-fed induction generators

    NARCIS (Netherlands)

    Tien, H. N.; Scherer, C. W.; Scherpen, J. M. A.

    2008-01-01

    Parameters of electrical machines are usually varying with time in a smooth way due to changing operating conditions, such as variations in the machine temperature and/or the magnetic saturation. This paper is concerned with robust stability analysis of controlled Doubly-Fed Induction Generators

  10. High Order Sliding Mode Control of Doubly-fed Induction Generator under Unbalanced Grid Faults

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2013-01-01

    This paper deals with a doubly-fed induction generator-based (DFIG) wind turbine system under grid fault conditions such as: unbalanced grid voltage, three-phase grid fault, using a high order sliding mode control (SMC). A second order sliding mode controller, which is robust with respect...

  11. Hopf bifurcation and eigenvalue sensitivity analysis of doubly fed induction generator wind turbine system

    DEFF Research Database (Denmark)

    Yang, Li Hui; Xu, Zhao; Østergaard, Jacob

    2010-01-01

    This paper first presents the Hopf bifurcation analysis for a vector-controlled doubly fed induction generator (DFIG) which is widely used in wind power conversion systems. Using three-phase back-to-back pulse-width-modulated (PWM) converters, DFIG can keep stator frequency constant under variabl...

  12. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    DEFF Research Database (Denmark)

    Hansen, A.D.; Iov, F.; Sørensen, Poul Ejnar

    2004-01-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind tu......-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT. Simulation results are performed and analyzed in different normal operating conditions....

  13. Doubly Fed Induction Generator Wind Turbines with Fuzzy Controller: A Survey

    Directory of Open Access Journals (Sweden)

    J. S. Sathiyanarayanan

    2014-01-01

    Full Text Available Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG due to their advantages over other wind turbine generators (WTGs. Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.

  14. Doubly fed induction generator wind turbines with fuzzy controller: a survey.

    Science.gov (United States)

    Sathiyanarayanan, J S; Kumar, A Senthil

    2014-01-01

    Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.

  15. Sizing of the Series Dynamic Breaking Resistor in a Doubly Fed Induction Generator Wind Turbine

    DEFF Research Database (Denmark)

    Soliman, Hammam; Wang, Huai; Zhou, Dao

    2014-01-01

    This paper investigates the effect of Series Dynamic Breaking Resistor (SDBR) sizing on a Doubly Fed Induction Generator (DFIG) based wind power conversion system. The boundary of the SDBR value is firstly derived by taking into account the controllability of the rotor side converter and the maxi......This paper investigates the effect of Series Dynamic Breaking Resistor (SDBR) sizing on a Doubly Fed Induction Generator (DFIG) based wind power conversion system. The boundary of the SDBR value is firstly derived by taking into account the controllability of the rotor side converter...... and the maximum allowable voltage of the stator. Then the impact of the SDBR value on the rotor current, stator voltage, DC-link voltage, reactive power capability and introduced power loss during voltage sag operation is evaluated by simulation. The presented study enables a trade-off sizing of the SDBR among...

  16. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Anca D.; Soerensen, Poul [Risoe National Laboratory, Roskilde (Denmark). Wind Energy Dept.; Iov, Florin; Blaabjerg, Frede [Aalborg Univ. (Denmark). Inst. of Energy Technology

    2004-07-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind turbine. The present control method is designed for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wider range of wind speeds. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT. Simulation results are performed and analyzed in different normal operating conditions.

  17. Flicker study on variable speed wind turbines with doubly fed induction generators

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    to a conclusion that the factors mentioned above have different influences on flicker emission compared with that in the case of the fixed speed wind turbine. Flicker mitigation is realized by output reactive power control of the variable speed wind turbine with doubly fed induction generator. Simulation results...... show the wind turbine output reactive power control provides an effective means for flicker mitigation regardless of mean wind speed, turbulence intensity and short circuit capacity ratio.......Grid connected wind turbines may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a doubly fed induction generator developed in the simulation tool of PSCAD/EMTDC. Flicker emission of variable speed wind turbines...

  18. Modeling and Simulation of Generator Side Converter of Doubly Fed Induction Generator-Based Wind Power Generation System

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Blaabjerg, Frede

    2010-01-01

    A real wind power generation system is given in this paper. SVM control strategy and vector control is applied for generator side converter and doubly fed induction generator respectively. First the mathematical models of the wind turbine rotor, drive train, generator side converter are described...

  19. Structural Design Optimization of Doubly-Fed Induction Generators Using GeneratorSE

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Fingersh, Lee J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Arthurs, Claire [Georgia Institute of Technology

    2017-11-13

    A wind turbine with a larger rotor swept area can generate more electricity, however, this increases costs disproportionately for manufacturing, transportation, and installation. This poster presents analytical models for optimizing doubly-fed induction generators (DFIGs), with the objective of reducing the costs and mass of wind turbine drivetrains. The structural design for the induction machine includes models for the casing, stator, rotor, and high-speed shaft developed within the DFIG module in the National Renewable Energy Laboratory's wind turbine sizing tool, GeneratorSE. The mechanical integrity of the machine is verified by examining stresses, structural deflections, and modal properties. The optimization results are then validated using finite element analysis (FEA). The results suggest that our analytical model correlates with the FEA in some areas, such as radial deflection, differing by less than 20 percent. But the analytical model requires further development for axial deflections, torsional deflections, and stress calculations.

  20. Control of variable speed wind turbine with doubly-fed induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Iov, F.; Blaabjerg, F. [Aalborg Univ., Inst. of Energy Technology, Aalborg (Denmark)

    2004-07-01

    draIn this paper, a Control method suitable for a variable speed grid connected pitch-controlled wind turbine with doubly-fed induction generator (DFIG) is developed. The targets of the Control system are: 1) to Control the power drawn from the wind turbine in order to track the wind turbine optimum operation point 2) to limit the power in case of high wind speeds and 3) to Control the reactive power interchanged between the wind turbine generator and the grid. The considered configuration of DFIG is an induction generator with a wound rotor connected to the grid through a back-to-back power converter and a stator directly connected to the grid. The paper presents the overall Control system of the variable speed DFIG wind turbine, with focus on the Control strategies and algorithms applied at each hierarchical Control level of the wind turbine. There are two Control levels: a DFIG Control level and wind turbine Control level. The DFIG Control level contains a fast Control of the power converter and of the doubly-fed induction generator and it has as goal to Control the active and reactive power of the wind turbine independently. The wind turbine Control level supervises with Control signals both the DFIG Control level and the hydraulic pitch Control system of the wind turbine. The present Control method is designed for normal continuous operations. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT, which makes possible to investigate the dynamic performance of gid-connected wind turbines as a part of realistic electrical grid models. Several significant simulation results are performed With the overall Control-implemented algorithm applied on a variable speed, variable pitch wind turbine model. (au)

  1. Dynamic participation of doubly fed induction generator in automatic generation control

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Praghnesh [Department of Electrical Engineering, Charotar Institute of Technology, Changa, Gujarat-388421 (India); Roy, Ranjit [Department of Electrical Engineering, S.V. National Institute of Technology, Surat, Gujarat-395007 (India); Ghoshal, S.P. [Department of Electrical Engineering, National Institute of Technology, Durgapur, West Bengal-713209 (India)

    2011-04-15

    Increasing levels of wind generation have resulted in an urgent need for the assessment of their impact on frequency control of power systems. The displacement of conventional generation with wind generation will result in erosion of system frequency. The paper analyzed the dynamic participation of doubly fed induction generator (DFIG) to system frequency responses of two-area interconnected power system having variety of conventional generating units. Frequency control support function responding proportionally to frequency deviation is proposed to take out the kinetic energy of turbine blades in order to improve the frequency response of the system. Impacts of different wind penetrations in the system and varying active power support from wind farm on frequency control have been investigated. Integral gains of AGC loop are optimized through craziness-based particle swarm optimization (CRPSO) in order to have optimal transient responses of area frequencies, tie-line power deviation and DFIG parameters. (author)

  2. Effects of Wind Turbines Equipped with Doubly-fed Induction Generators on Distance Protection

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Nowadays wind energy is the fastest growing renewable energy resource in the world. The problems of integrating wind farms are caused by changes of wind speed during a day. Moreover, the behaviors of wind turbines equipped with doubly-fed induction generators differ fundamentally from synchronous generators. Therefore, more considerations are needed to analyze the performances of the distance protection relays. The protection of a wind farm with distance relay is inspected. By changing the conditions of the wind farm, the characteristics of the distance relay are studied.

  3. Flicker Mitigation Strategy for a Doubly Fed Induction Generator by Torque Control

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Hu, Weihao; Chen, Zhe

    2014-01-01

    induction generator is presented to investigate the flicker mitigation. Taking advantage of the large inertia of the wind turbine rotor, a generator torque control (GTC) strategy is proposed, so that the power oscillation is stored as the kinetic energy of the wind turbine rotor, thus the flicker emission...... is an effective means for flicker mitigation of variable speed wind turbines during continuous operation.......Owing to the rotational sampling of turbulence, wind shear and tower shadow effects grid connected variable speed wind turbines could lead to the power fluctuations which may produce flicker during continuous operation. A model of an megawatt (MW)-level variable speed wind turbine with a doubly fed...

  4. Modern control strategies of doubly-fed induction generator based wind turbine system

    DEFF Research Database (Denmark)

    Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

    2016-01-01

    A doubly-fed induction generator (DFIG) based configuration is still preferred by wind turbine manufactures due to the cost-effective power converter and independent control of the active power and reactive power. To cope with stricter grid codes (e.g. reactive power compensation, low voltage ride......, with the control targets of the smooth active and reactive power or the balances and sinusoidal current of the rotor-side converter and the grid-side converter. Finally, a bandwidth based repetitive controller is evaluated to improve the DFIG system's robustness against grid frequency deviation....

  5. Advanced control of a doubly-fed induction generator for wind energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Poitiers, F.; Bouaouiche, T.; Machmoum, M. [Institut de Recherche en Electronique et Electrotechnique de Nantes Atlantique, rue Christian Pauc, 44306 Nantes (France)

    2009-07-15

    The aim of this paper is to propose a control method for a doubly-fed induction generator used in wind energy conversion systems. First, stator active and reactive powers are regulated by controlling the machine inverter with three different controllers: proportional-integral, polynomial RST based on pole placement theory and Linear Quadratic Gaussian. The machine is tested in association with a wind-turbine emulator. Secondly a control strategy for the grid-converter is proposed. Simulations results are presented and discussed for each converter control and for the whole system. (author)

  6. Centralised power control of wind farm with doubly fed induction generators

    DEFF Research Database (Denmark)

    Hansen, A.D.; Sørensen, Poul Ejnar; Iov, F.

    2006-01-01

    At the moment, the control ability of wind farms is a prime research concern for the grid integration of large wind farms, due to their required active role in the power system. This paper describes the on-going work of a research project, whose overall objective is to analyse and assess...... the possibilities for control of different wind farm concepts. The scope of this paper is the control of a wind farm made up exclusively of doubly fed induction generators. The paper addresses the design and implementation issues of such a controller and focuses on the ability of the wind farm control strategy...

  7. Comparison of control strategies for Doubly fed induction generator under recurring grid faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2014-01-01

    The new grid codes demand the wind turbine systems to ride through recurring grid faults. Many control strategies have been proposed for the Doubly Fed Induction Generator under single grid fault, but their performance under recurring grid faults have not been studied yet. In this paper, five...... different control strategies for DFIG to ride through single grid faults are presented, and their performance under recurring grid faults are analyzed. The controllable range, stator time constant and torque fluctuations of the DFIG with different control strategies are compared. The results are verified...

  8. Doubly fed induction generator based wind turbine systems subject to recurring grid faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2014-01-01

    New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the Doubly Fed Induction Generator wind turbine system under recurring grid faults is analyzed. The stator natural flux produced by the voltage recovery after the first grid fault...... may be superposed on the stator natural flux produced by the second grid fault, and it may result in large current and voltage transient. The damping of the stator natural flux can be accelerated with a rotor natural current in its opposite direction after voltage recovery, but larger torque....... The performance of DFIG under recurring grid faults is verified by the simulation and experiments....

  9. Control of variable speed wind turbines with doubly-fed induction generators

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P.; Iov, F.; Blaabjerg, F.

    2005-07-01

    The paper presents an overall control method for variable speed pitch controlled wind turbines with doubly-fed induction generators (DFIG). Emphasis is on control strategies and algorithms applied at each hierarchical control level of the wind turbine. The objectives of the control system are: 1) to control the power drawn from the wind turbine in order to track the wind turbine maximum power operation point, 2) to limit the power in case of large wind speeds, and 3) to control the reactive power interchanged between the wind turbine generator and the grid. The present control method is designed for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wide range of wind speeds. The model of the variable speed, variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DlgSILENT PowerFactory which allows investigation of the dynamic performance of grid-connected wind turbines within realistic electrical grid models. Simulation results are presented and analysed in different normal operating conditions. (author)

  10. Optimal design of power system stabilizer for power systems including doubly fed induction generator wind turbines

    International Nuclear Information System (INIS)

    Derafshian, Mehdi; Amjady, Nima

    2015-01-01

    This paper presents an evolutionary algorithm-based approach for optimal design of power system stabilizer (PSS) for multi-machine power systems that include doubly fed induction generator wind turbines. The proposed evolutionary algorithm is an improved particle swarm optimization named chaotic particle swarm optimization with passive congregation (CPSO-PC) applied for finding the optimal settings of PSS parameters. Two different eigenvalue-based objectives are combined as the objective function for the optimization problem of tuning PSS parameters. The first objective function comprises the damping factor of lightly damped electro-mechanical modes and the second one includes the damping ratio of these modes. The effectiveness of the proposed method to design PSS for the power systems including DFIG (Doubly Fed Induction Generator) is extensively demonstrated through eigenvalue analysis and time-domain simulations and also by comparing its simulation results with the results of other heuristic optimization approaches. - Highlights: • A new optimization model for design of PSS in power systems including DFIG is proposed. • A detailed and realistic modeling of DFIG is presented. • A new evolutionary algorithm is suggested for solving the optimization problem of designing PSS

  11. State reference design and saturated control of doubly-fed induction generators under voltage dips

    Science.gov (United States)

    Tilli, Andrea; Conficoni, Christian; Hashemi, Ahmad

    2017-04-01

    In this paper, the stator/rotor currents control problem of doubly-fed induction generator under faulty line voltage is carried out. Common grid faults cause a steep decline in the line voltage profile, commonly denoted as voltage dip. This point is critical for such kind of machines, having their stator windings directly connected to the grid. In this respect, solid methodological nonlinear control theory arguments are exploited and applied to design a novel controller, whose main goal is to improve the system behaviour during voltage dips, endowing it with low voltage ride through capability, a fundamental feature required by modern Grid Codes. The proposed solution exploits both feedforward and feedback actions. The feedforward part relies on suitable reference trajectories for the system internal dynamics, which are designed to prevent large oscillations in the rotor currents and command voltages, excited by line perturbations. The feedback part uses state measurements and is designed according to Linear Matrix Inequalities (LMI) based saturated control techniques to further reduce oscillations, while explicitly accounting for the system constraints. Numerical simulations verify the benefits of the internal dynamics trajectory planning, and the saturated state feedback action, in crucially improving the Doubly-Fed Induction Machine response under severe grid faults.

  12. A class of flux observers for doubly-fed induction generators used in small power wind generation systems

    DEFF Research Database (Denmark)

    Lascu, C.; Boldea, I.; Blaabjerg, Frede

    2013-01-01

    This paper investigates a family of stator and rotor flux observers for sensorless operation of doubly-fed induction generators (DFIG). Four stator flux observer topologies are described and compared. All proposed schemes use the voltage and current models connected in parallel or in series...

  13. Dynamic Average-Value Modeling of Doubly-Fed Induction Generator Wind Energy Conversion Systems

    Science.gov (United States)

    Shahab, Azin

    In a Doubly-fed Induction Generator (DFIG) wind energy conversion system, the rotor of a wound rotor induction generator is connected to the grid via a partial scale ac/ac power electronic converter which controls the rotor frequency and speed. In this research, detailed models of the DFIG wind energy conversion system with Sinusoidal Pulse-Width Modulation (SPWM) scheme and Optimal Pulse-Width Modulation (OPWM) scheme for the power electronic converter are developed in detail in PSCAD/EMTDC. As the computer simulation using the detailed models tends to be computationally extensive, time consuming and even sometimes not practical in terms of speed, two modified approaches (switching-function modeling and average-value modeling) are proposed to reduce the simulation execution time. The results demonstrate that the two proposed approaches reduce the simulation execution time while the simulation results remain close to those obtained using the detailed model simulation.

  14. Condition monitoring of a wind turbine doubly-fed induction generator through current signature analysis

    Science.gov (United States)

    Artigao, Estefania; Honrubia-Escribano, Andres; Gomez-Lazaro, Emilio

    2017-11-01

    Operation and maintenance (O&M) of wind turbines is recently becoming the spotlight in the wind energy sector. While wind turbine power capacities continue to increase and new offshore developments are being installed, O&M costs keep raising. With the objective of reducing such costs, the new trends are moving from corrective and preventive maintenance toward predictive actions. In this scenario, condition monitoring (CM) has been identified as the key to achieve this goal. The induction generator of a wind turbine is a major contributor to failure rates and downtime where doubly-fed induction generators (DFIG) are the dominant technology employed in variable speed wind turbines. The current work presents the analysis of an in-service DFIG. A one-year measurement campaign has been used to perform the study. Several signal processing techniques have been applied and the optimal method for CM has been identified. A diagnosis has been reached, the DFIG under study shows potential gearbox damage.

  15. Grid-connected in-stream hydroelectric generation based on the doubly fed induction machine

    Science.gov (United States)

    Lenberg, Timothy J.

    Within the United States, there is a growing demand for new environmentally friendly power generation. This has led to a surge in wind turbine development. Unfortunately, wind is not a stable prime mover, but water is. Why not apply the advances made for wind to in-stream hydroelectric generation? One important advancement is the creation of the Doubly Fed Induction Machine (DFIM). This thesis covers the application of a gearless DFIM topology for hydrokinetic generation. After providing background, this thesis presents many of the options available for the mechanical portion of the design. A mechanical turbine is then specified. Next, a method is presented for designing a DFIM including the actual design for this application. In Chapter 4, a simulation model of the system is presented, complete with a control system that maximizes power generation based on water speed. This section then goes on to present simulation results demonstrating proper operation.

  16. Advanced modelling of doubly fed induction generator wind turbine under network disturbance

    DEFF Research Database (Denmark)

    Seman, S.; Iov, Florin; Niiranen, J.

    This paper presents a variable speed wind turbine simulator. The simulator is used for a 2 MW wind turbine transient behavior study during a short-term symmetrical network disturbance. The mechanical part of wind turbine model consists of the rotor aerodynamic model, the wind turbine control...... converter, the model of the main transformer and a simple model of the grid. The simulation results obtained by means of the detailed wind turbine model are compared with the results obtained from a simplified simulator with an analytical model and FEM model of DFIG. The comparison of the results shows...... and the drive train model. The Doubly Fed Induction Generator (DFIG) is represented by an analytical two-axis model with constant lumped parameters and by Finite Element Method (FEM) based model. The model of the DFIG is coupled with the model of the passive crowbar protected and DTC controlled frequency...

  17. Control of Doubly-Fed Induction Generator to Ride-Through Recurring Grid Faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Xu, Dehong; Zhu, Nan

    2016-01-01

    The wind turbine system (WTS) is required to ride-through recurring grid faults by the new grid codes. Under single grid faults, the fault ride-through (FRT) strategy with rotor-side crowbar is normally used for the doubly-fed induction generator (DFIG) WTS. However, under recurring faults, larger...... transient current and voltage may be produced, and the DFIG may fail to ride-through the second fault even with the rotor-side crowbar. The crowbar can be active again during the voltage recovery, but large electromagnetic torque (EM-torque) fluctuations will be introduced. The reliability of the mechanical...... system will be influenced. In this paper, an FRT strategy for the DFIG WTS to ride-through recurring symmetrical grid faults is investigated. An improved control strategy is introduced and it is applied during the voltage recovery of the grid faults. The decay of the stator natural flux can...

  18. Comparison and analysis of transient performances for doubly fed induction generator wind turbine under grid voltage dip

    DEFF Research Database (Denmark)

    Li, H.; Ye, R.; Han, L.

    2010-01-01

    In order to entirely analyze the transient performances of a grid-connected doubly fed induction generator (DFIG) wind turbine under the different operational states, based on the transient models of DFIG, a two-mass wind turbine electrical equivalent model considering the torsional flexibility o...

  19. Complementary Power Control for Doubly Fed Induction Generator-Based Tidal Stream Turbine Generation Plants

    Directory of Open Access Journals (Sweden)

    Khaoula Ghefiri

    2017-06-01

    Full Text Available The latest forecasts on the upcoming effects of climate change are leading to a change in the worldwide power production model, with governments promoting clean and renewable energies, as is the case of tidal energy. Nevertheless, it is still necessary to improve the efficiency and lower the costs of the involved processes in order to achieve a Levelized Cost of Energy (LCoE that allows these devices to be commercially competitive. In this context, this paper presents a novel complementary control strategy aimed to maximize the output power of a Tidal Stream Turbine (TST composed of a hydrodynamic turbine, a Doubly-Fed Induction Generator (DFIG and a back-to-back power converter. In particular, a global control scheme that supervises the switching between the two operation modes is developed and implemented. When the tidal speed is low enough, the plant operates in variable speed mode, where the system is regulated so that the turbo-generator module works in maximum power extraction mode for each given tidal velocity. For this purpose, the proposed back-to-back converter makes use of the field-oriented control in both the rotor side and grid side converters, so that a maximum power point tracking-based rotational speed control is applied in the Rotor Side Converter (RSC to obtain the maximum power output. Analogously, when the system operates in power limitation mode, a pitch angle control is used to limit the power captured in the case of high tidal speeds. Both control schemes are then coordinated within a novel complementary control strategy. The results show an excellent performance of the system, affording maximum power extraction regardless of the tidal stream input.

  20. Active Power Optimal Control of Wind Turbines with Doubly Fed Inductive Generators Based on Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Guo Jiuwang

    2015-01-01

    Full Text Available Because of the randomness and fluctuation of wind energy, as well as the impact of strongly nonlinear characteristic of variable speed constant frequency (VSCF wind power generation system with doubly fed induction generators (DFIG, traditional active power control strategies are difficult to achieve high precision control and the output power of wind turbines is more fluctuated. In order to improve the quality of output electric energy of doubly fed wind turbines, on the basis of analyzing the operating principles and dynamic characteristics of doubly fed wind turbines, this paper proposes a new active power optimal control method of doubly fed wind turbines based on predictive control theory. This method uses state space model of wind turbines, based on the prediction of the future state of wind turbines, moves horizon optimization, and meanwhile, gets the control signals of pitch angle and generator torque. Simulation results show that the proposed control strategies can guarantee the utilization efficiency for wind energy. Simultaneously, they can improve operation stability of wind turbines and the quality of electric energy.

  1. Loss of Excitation Detection in Doubly Fed Induction Generator by Voltage and Reactive Power Rate

    Directory of Open Access Journals (Sweden)

    M. J. Abbasi

    2016-12-01

    Full Text Available The doubly fed induction generator (DFIG is one of the most popular technologies used in wind power systems. With the growing use of DFIGs and increasing power system dependence on them in recent years, protecting of these generators against internal faults is more considered. Loss of excitation (LOE event is among the most frequent failures in electric generators. However, LOE detection studies heretofore were usually confined to synchronous generators. Common LOE detection methods are based on impedance trajectory which makes the system slow and also prone to interpret a stable power swing (SPS as a LOE fault. This paper suggests a new method to detect the LOE based on the measured variables from the DFIG terminal. In this combined method for LOE detection, the rate of change of both the terminal voltage and the output reactive power are utilized and for SPS detection, the fast Fourier transform (FFT analysis of the output instantaneous active power has been used. The performance of the proposed method was evaluated using Matlab/Simulink interface for various power capacities and operating conditions. The results proved the method's quickness, simplicity and security.

  2. A Condensed Introduction to the Doubly Fed Induction Generator Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Julius Mwaniki

    2017-01-01

    Full Text Available The increase in wind power penetration, at 456 GW as of June 2016, has resulted in more stringent grid codes which specify that the wind energy conversion systems (WECS must remain connected to the system during and after a grid fault and, furthermore, must offer grid support by providing reactive currents. The doubly fed induction generator (DFIG WECS is a well-proven technology, having been in use in wind power generation for many years and having a large world market share due to its many merits. Newer technologies such as the direct drive gearless permanent magnet synchronous generator have come up to challenge its market share, but the large number of installed machines ensures that it remains of interest in the wind industry. This paper presents a concise introduction of the DFIG WECS covering its construction, operation, merits, demerits, modelling, control types, levels and strategies, faults and their proposed solutions, and, finally, simulation. Qualities for the optimal control strategy are then proposed. The paper is intended to cover major issues related to the DFIG WECS that are a must for an overview of the system and hence serve as an introduction especially for new entrants into this area of study.

  3. A Concise Presentation of Doubly Fed Induction Generator Wind Energy Conversion Systems Challenges and Solutions

    Directory of Open Access Journals (Sweden)

    Julius Mwaniki

    2017-01-01

    Full Text Available There is increased worldwide wind power generation, a large percentage of which is grid connected. The doubly fed induction generator (DFIG wind energy conversion system (WECS has many merits and, as a result, large numbers have been installed to date. The DFIG WECS operation, under both steady state and fault conditions, is of great interest since it impacts on grid performance. This review paper presents a condensed look at the various applied solutions to the challenges of the DFIG WECS including maximum power point tracking, common mode voltages, subsynchronous resonance, losses, modulation, power quality, and faults both internal and from the grid. It also looks at approaches used to meet the increasingly stringent grid codes requirements for the DFIG WECS to not only ride through faults but also provide voltage support. These are aspects of the DFIG WECS that are critical for system operators and prospective investors and can also serve as an introduction for new entrants into this area of study.

  4. Simplified model of wind turbines with doubly-fed induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Timbus, Adrian; Korba, Petr [ABB Corporate Research, Baden-Daettwil (Switzerland); Vilhunen, Antti; Pepe, Giuseppe; Seman, Slavomir; Niiranen, Jouko [ABB Oy, Helsinki (Finland)

    2011-07-01

    With an ever increasing pace of wind power installations around the world, the necessity of studying the functionality of the power system with intermittent generation becomes a critical necessity. Power system studies have been carried out by different organizations, using mainly generic models of turbines available in most utilized software tools such as PSS/E, PowerFactory, PSLF, etc. Very often the system operators ask for models of turbines which represent a specific vendor, hence vendor specific models become also available in these tools. These are necessary to evaluate a realistic response of the grid when a particular technology is used for the wind turbines. This paper elaborates on the development of a simplified model of a wind turbine equipped with Doubly-Fed Induction Generator. The model is meant to be suitable for power system studies and should reflect the concept provided by ABB. This model comprises a series of state machines which reflect the functionality of the turbine from start-up until shut-down due to high wind speeds. In addition, attention and efforts were focused to provide the right functionality during low voltage values, - the so called low voltage ride through feature - and to support the grid after voltage sag. (orig.)

  5. Transient Performance Improvement of Wind Turbines with Doubly Fed Induction Generators Using Active Damping Control Strategy

    Directory of Open Access Journals (Sweden)

    Saeed Soleymani

    2016-01-01

    Full Text Available This paper Analytically investigates the effects of system and controller parameters and operating conditions on the dynamic and transient behavior of wind turbines (WTs with doubly-fed induction generators (DFIGs under voltage dips and wind speed fluctuations. Also, it deals with the design considerations regarding rotor and speed controllers. The poorly damped electrical and mechanical modes of the system are identified, and the effects of system parameters, and speed/rotor controllers on these modes are investigated by modal and sensitivity analyses. The results of theoretical studies are verified by time domain simulations. It is found that the dynamic behavior of the DFIG-based WT under voltage dips is strongly affected by the stator dynamics. Further, it is shown that the closed loop bandwidth of the rotor current control, rotor current damping, DFIG power factor and the rotor back-emf voltages have high impact on the stator modes and consequently on the DFIG dynamic behavior. Moreover, it is shown that the dynamic behavior of DFIG-based WT under wind speed fluctuation is significantly dependent on the bandwidth and damping of speed control loop.

  6. Detailed Transients Simulation of a Doubly Fed Induction Generator Wind Turbine System with the EMTP-Type OVNI Simulator

    OpenAIRE

    Lukić Armstrong, Mažana; R. Martí, José; Kundur, Prabha

    2017-01-01

    Doubly fed induction generator wind turbines are increasingly used in new wind turbine installations all over the world. Growing concerns about the impact of a large number of these generators on transient and voltage stability of power system networks has led engineers to revisit modelling and simulation practices used for system stability analyses. In this paper, the latest advancements in design of the general purpose power system simulator OVNI developed at the University o...

  7. Centralised control of wind farm with doubly-fed induction generators

    DEFF Research Database (Denmark)

    Hansen, A.D.; Sørensen, Poul Ejnar; Iov, F.

    2005-01-01

    This paper describes the development of an advanced wind farm controller for a wind farm made-up exclusively of doubly-fed generators. The overall aim of such controller is to enable the wind farms to behave as active controllable components in the power system. The attention is mainly drawn...... to the ability of the wind farm control strategy to regulate the wind farm power production to the reference power ordered by the system operators. The performance of the control strategy is assessed and discussed by means of normal operation simulations of a grid connected wind farm....

  8. Transient Response Improvement of Microgrids Exploiting the Inertia of a Doubly-Fed Induction Generator (DFIG

    Directory of Open Access Journals (Sweden)

    Christina N. Papadimitriou

    2010-06-01

    Full Text Available Storage devices are introduced in microgrids in order to secure their power quality, power regularity and offer ancillary services in a transient period. In the transition period of a low voltage microgrid, from the connected mode of operation to the islanded mode of operation, the power unbalance can be partly covered by the inertia energy of the existing power sources. This paper proposes fuzzy local controllers exploiting the inertia of a Wind Turbine (WT with a Doubly Fed Induction Generator (DFIG, if such a machine exists in the microgrid, in order to decrease the necessary storage devices and the drawbacks that arise. The proposed controllers are based in fuzzy logic due to the non linear and stochastic behavior of the system. Two cases are studied and compared during the transient period where the microgrid architecture and the DFIG controller differ. In the first case, the understudy microgrid includes a hybrid fuel cell system (FCS-battery system and a WT with a DFIGURE. The DFIG local controller in this case is also based in fuzzy logic and follows the classical optimum power absorption scenario for the WT. The transition of the microgrid from the connected mode of operation to the islanded mode is evaluated and, especially, the battery contribution is estimated. In the second case, the battery is eliminated. The fuzzy controller of the DFIG during the transition provides primary frequency control and local bus voltage support exploiting the WT inertia. The response of the system is estimated in both cases using MATLAB/Simulink software package.

  9. Effects of voltage unbalance and system harmonics on the performance of doubly fed induction wind generators

    Science.gov (United States)

    Kiani, Morgan Mozhgan

    Inherent difficulties in management of electric power in the presence of an increasing demand for more energy, non-conventional loads such as digital appliances, and non-sustainable imported fossil fuels has initiated a multi-folded effort by many countries to restructure the way electric energy is generated, dispatched, and consumed. Smart power grid is the manifestation of many technologies that would eventually transforms the existing power grid into a more flexible, fault resilient, and intelligent system. Integration of distributed renewable energy sources plays a central role in successful implementation of this transformation. Among the renewable options, wind energy harvesting offers superior engineering and economical incentives with minimal environmental impacts. Doubly fed induction generators (DFIG) have turned into a serious contender for wind energy generators due to their flexibility in control of active and reactive power with minimal silicon loss. Significant presence of voltage unbalance and system harmonics in finite inertia transmission lines can potentially undermine the reliability of these wind generators. The present dissertation has investigated the impacts of system unbalances and harmonics on the performance of the DFIG. Our investigation indicates that these effects can result in an undesirable undulation in the rotor shaft which can potentially invoke mechanical resonance, thereby causing catastrophic damages to the installations and the power grid. In order to remedy the above issue, a control solution for real time monitoring of the system unbalance and optimal excitation of the three phase rotor currents in a DFIG is offered. The optimal rotor currents will create appropriate components of the magneto-motive force in the airgap that will actively compensate the undesirable magnetic field originated by the stator windings. Due to the iterative nature of the optimization procedure, field reconstruction method has been incorporated

  10. Fault-tolerant control for current sensors of doubly fed induction generators based on an improved fault detection method

    DEFF Research Database (Denmark)

    Li, Hui; Yang, Chao; Hu, Yaogang

    2014-01-01

    Fault-tolerant control of current sensors is studied in this paper to improve the reliability of a doubly fed induction generator (DFIG). A fault-tolerant control system of current sensors is presented for the DFIG, which consists of a new current observer and an improved current sensor fault...... detection algorithm, and fault-tolerant control system are investigated by simulation. The results indicate that the outputs of the observer and the sensor are highly coherent. The fault detection algorithm can efficiently detect both soft and hard faults in current sensors, and the fault-tolerant control...

  11. Optimal Controller Design of a Wind Turbine with Doubly Fed Induction Generator for Small Signal Stability Enhancement

    DEFF Research Database (Denmark)

    Yang, Lihui; Yang, Guangya; Xu, Zhao

    2010-01-01

    Multi-objective optimal controller design of a doubly fed induction generator (DFIG) wind turbine system using Differential Evolution (DE) is presented in this chapter. A detailed mathematical model of DFIG wind turbine with a close loop vector control system is developed. Based on this, objective...... functions, addressing the steady state stability and dynamic performance at different operating conditions are implemented to optimize the controller parameters of both the rotor and grid side converters. A superior ε-constraint method and method of adaptive penalties are applied to handle the multi...

  12. New control strategy of stand-alone brushless doubly-fed induction generator for supplying unbalanced loads in ship shaft power generation system

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Xiong, Fei

    2017-01-01

    The ship shaft power generation system based on a stand-alone brushless doubly-fed induction generator (BDFIG) have demonstrated excellent saving-energy performance. This paper presents a new control scheme of the stand-alone BDFIG for supplying unbalanced loads in the ship shaft power generation...

  13. Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System with Optimized Grid Filter

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2014-01-01

    The modern grid requirement has caused that the wind power system behaves more like conventional rotating generators and it is able to support certain amount of the reactive power. For a typical doubly-fed induction generator wind turbine system, the reactive power can be supported either through...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterwards, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...... the rotor-side converter or the grid-side converter. This paper firstly compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...

  14. Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System With Optimized Grid Filter

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2015-01-01

    The modern grid requirement has caused that the wind power system behaves more like conventional rotating generators, and it is able to support certain amount of the reactive power. For a typical doubly fed induction generator (DFIG) wind turbine system, the reactive power can be supported either...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterward, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...... through the rotor-side converter or the grid-side converter. This paper first compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...

  15. Dual-loop self-optimizing robust control of wind power generation with Doubly-Fed Induction Generator.

    Science.gov (United States)

    Chen, Quan; Li, Yaoyu; Seem, John E

    2015-09-01

    This paper presents a self-optimizing robust control scheme that can maximize the power generation for a variable speed wind turbine with Doubly-Fed Induction Generator (DFIG) operated in Region 2. A dual-loop control structure is proposed to synergize the conversion from aerodynamic power to rotor power and the conversion from rotor power to the electrical power. The outer loop is an Extremum Seeking Control (ESC) based generator torque regulation via the electric power feedback. The ESC can search for the optimal generator torque constant to maximize the rotor power without wind measurement or accurate knowledge of power map. The inner loop is a vector-control based scheme that can both regulate the generator torque requested by the ESC and also maximize the conversion from the rotor power to grid power. An ℋ(∞) controller is synthesized for maximizing, with performance specifications defined based upon the spectrum of the rotor power obtained by the ESC. Also, the controller is designed to be robust against the variations of some generator parameters. The proposed control strategy is validated via simulation study based on the synergy of several software packages including the TurbSim and FAST developed by NREL, Simulink and SimPowerSystems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  16. The Virtual Resistance Control Strategy for HVRT of Doubly Fed Induction Wind Generators Based on Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Zhen Xie

    2014-01-01

    Full Text Available Grid voltage swell will cause transient DC flux component in the doubly fed induction generator (DFIG stator windings, creating serious stator and rotor current and torque oscillation, which is more serious than influence of the voltage dip. It is found that virtual resistance manages effectively to suppress rotor current and torque oscillation, avoid the operation of crowbar circuit, and enhance its high voltage ride through technology capability. In order to acquire the best virtual resistance value, the excellent particle library (EPL of dynamic particle swarm optimization (PSO algorithm is proposed. It takes the rotor voltage and rotor current as two objectives, which has a fast convergence performance and high accuracy. Simulation and experimental results verify the effectiveness of the virtual resistance control strategy.

  17. An Improved Control Strategy of Limiting the DC-Link Voltage Fluctuation for a Doubly Fed Induction Wind Generator

    DEFF Research Database (Denmark)

    Yao, J.; Li, H.; Liao, Y.

    2008-01-01

    The paper presents to develop a new control strategy of limiting the dc-link voltage fluctuation for a back-to-back pulsewidth modulation converter in a doubly fed induction generator (DFIG) for wind turbine systems. The reasons of dc-link voltage fluctuation are analyzed. An improved control...... strategy with the instantaneous rotor power feedback is proposed to limit the fluctuation range of the dc-link voltage. An experimental rig is set up to valid the proposed strategy, and the dynamic performances of the DFIG are compared with the traditional control method under a constant grid voltage....... Furthermore, the capabilities of keeping the dc-link voltage stable are also compared in the ride-through control of DFIG during a three-phase grid fault, by using a developed 2 MW DFIG wind power system model. Both the experimental and simulation results have shown that the proposed control strategy is more...

  18. Optimal controller design of a doubly fed induction generator wind turbine system for small signal stability enhancement

    DEFF Research Database (Denmark)

    Yang, Lihui; Yang, Guang-Ya; Xu, Zhao

    2010-01-01

    Multi-objective optimal controller design of a doubly-fed induction generator (DFIG) wind turbine system using differential evolution (DE) is presented. A detailed mathematical model of DFIG wind turbine with a closed-loop vector control system is developed. Based on this, objective functions...... and the constraint with DE, respectively. Eigenvalue analysis and time-domain simulations are performed on a single machine infinite bus system as well as a nine-bus multi-machine system with two DFIG wind turbines to illustrate the control performance of the DFIG wind turbine with the optimised controller...... addressing the steady-state stability and dynamic performance at different operating conditions are implemented to optimise the controller parameters of both the rotor and grid-side converters. A superior 1-constraint method and method of adaptive penalties are applied to handle the multi-objective problem...

  19. Three-phase short circuit calculation method based on pre-computed surface for doubly fed induction generator

    Science.gov (United States)

    Ma, J.; Liu, Q.

    2018-02-01

    This paper presents an improved short circuit calculation method, based on pre-computed surface to determine the short circuit current of a distribution system with multiple doubly fed induction generators (DFIGs). The short circuit current, injected into power grid by DFIG, is determined by low voltage ride through (LVRT) control and protection under grid fault. However, the existing methods are difficult to calculate the short circuit current of DFIG in engineering practice due to its complexity. A short circuit calculation method, based on pre-computed surface, was proposed by developing the surface of short circuit current changing with the calculating impedance and the open circuit voltage. And the short circuit currents were derived by taking into account the rotor excitation and crowbar activation time. Finally, the pre-computed surfaces of short circuit current at different time were established, and the procedure of DFIG short circuit calculation considering its LVRT was designed. The correctness of proposed method was verified by simulation.

  20. Implementation, Comparison and Application of an Average Simulation Model of a Wind Turbine Driven Doubly Fed Induction Generator

    Directory of Open Access Journals (Sweden)

    Lidula N. Widanagama Arachchige

    2017-10-01

    Full Text Available Wind turbine driven doubly-fed induction generators (DFIGs are widely used in the wind power industry. With the increasing penetration of wind farms, analysis of their effect on power systems has become a critical requirement. This paper presents the modeling of wind turbine driven DFIGs using the conventional vector controls in a detailed model of a DFIG that represents power electronics (PE converters with device level models and proposes an average model eliminating the PE converters. The PSCAD/EMTDC™ (4.6 electromagnetic transient simulation software is used to develop the detailed and the proposing average model of a DFIG. The comparison of the two models reveals that the designed average DFIG model is adequate for simulating and analyzing most of the transient conditions.

  1. Cost on Reliability and Production Loss for Power Converters in the Doubly Fed Induction Generator to Support Modern Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2016-01-01

    As wind farms are normally located in remote areas, many grid codes have been issued especially related to the reactive power support. Although the Doubly-Fed Induction Generator (DFIG) based power converter is able to control the active power and reactive power independently, the effects...... of providing reactive power on the lifetime of the power converter and the cost-of-energy of the whole system are seldom evaluated, even though it is an important topic. In this paper, the loss models of the DFIG system are established at various conditions of the reactive power injection. If the mission...... profile is taken into account, the lifespan of the power semiconductors as well as the cost of the reactive power can be calculated. It is concluded that an over-excited reactive power injection significantly reduces the power converter lifetime, only 1/4 of the case that there is no reactive power...

  2. Wind Turbine Power Generation Emulation Via Doubly Fed Induction Generator Control

    Science.gov (United States)

    2009-12-01

    vde thetas vqs_pu vds_pu synchronous...to stationary 0 ide_ref 200 Vdc_ref I_ref I_meas vqe PI iq I_ref I_meas vde PI id v_ref v_meas iqs PI Vdc 4 theta_s 3 ide 2 iqe 1 Vdc 21 between...1-1 x(-1)- a b a + b+ Sy stem Generator Variac P/S 60V 60HzVariac P/S 60V 60Hz 70 Vabc_s THETA CALCULATION 5 vde 4 vqe 3 Vas 2 Vdc_out 1

  3. Symbolic Solution Approach to Wind Turbine based on Doubly Fed Induction Generator Model

    DEFF Research Database (Denmark)

    Cañas–Carretón, M.; Gómez–Lázaro, E.; Martín–Martínez, S.

    2015-01-01

    –order induction generator is selected to model the electric machine, being this approach suitable to estimate the DFIG performance under transient conditions. The corresponding non–linear integro-differential equation system has been reduced to a linear state-space system by using an ad-hoc local linearization......This paper describes an alternative approach based on symbolic computations to simulate wind turbines equipped with Doubly–Fed Induction Generator (DFIG). The actuator disk theory is used to represent the aerodynamic part, and the one-mass model simulates the mechanical part. The 5th...

  4. Proportional-Resonant Control of Doubly-Fed Induction Generator Wind Turbines for Low-Voltage Ride-Through Enhancement

    Directory of Open Access Journals (Sweden)

    Zhan-Feng Song

    2012-11-01

    Full Text Available A novel control strategy is proposed in this paper for the rotor side converter (RSC of doubly-fed induction generator (DFIG-based wind power generation systems. It is supposed to enhance the low-voltage ride-through (LVRT capability of DFIGs during great-level grid voltage dips. The strategy consists of a proportional-resonant (PR controller and auxiliary PR controllers. The auxiliary controllers compensate the output voltage of the RSC in case of grid faults, thus limiting the rotor inrush current of DFIG and meeting the requirements of LVRT. Sequential-component decompositions of current are not required in the control system to improve the response of system. Since the resonant compensator is a double-side integrator, the auxiliary controllers can be simplified through coordinate transformation. The feasibility of the control strategy is validated by simulation on a 1.5 MW wind-turbine driven DFIG system. The impact of the RSC converter voltage rating on the LVRT capability of DFIG is investigated. Meanwhile, the influence of angular frequency detection and control parameters are also discussed. Compared with traditional vector control schemes based on PI current controllers, the presented control strategy effectively suppress rotor current and reduce oscillations of DFIG power and torque under grid faults.

  5. Active-Reactive Additional Damping Control of a Doubly-Fed Induction Generator Based on Active Disturbance Rejection Control

    Directory of Open Access Journals (Sweden)

    Yanfeng Ma

    2018-05-01

    Full Text Available Large-scale wind power interfacing to the power grid has an impact on the stability of the power system. However, with an additional damping controller of the wind generator, new ways for improving system damping and suppressing the low frequency oscillation (LFO of power systems can be put forward. In this paper, an active-reactive power additional damping controller based on active disturbance rejection control (ADRC is proposed. In order to improve the precision of the controller, the theory of data driven control is adopted, using the numerical algorithms for subspace state space system identification (N4SID to obtain the two order model of the ADRC controlled object. Based on the identification model, the ADRC additional damping controller is designed. Taking a 2-area 4-machine system containing the doubly fed induction generator (DFIG wind farm as an example, it is verified that the active-reactive additional damping controller designed in this paper performs well in suppressing negative-damping LFO and forced power oscillation. When the operation state of the power system changes, it can still restrain the LFO effectively, showing stronger robustness and better effectiveness compared to the traditional proportional–integral–derivative (PID additional damping controller.

  6. Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines.

    Science.gov (United States)

    Ebrahimkhani, Sadegh

    2016-07-01

    Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  7. Doubly Fed Induction Generator Wind Turbine Systems Subject to Recurring Symmetrical Grid Faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2016-01-01

    New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the doubly Ffed induction generator (DFIG) wind turbine system under recurring symmetrical grid faults is analyzed. The mathematical model of the DFIG under recurring symmetrical...... grid faults is established. The analysis is based on the DFIG wind turbine system with the typical low-voltage ride-through strategy-with rotor-side crowbar. The stator natural flux produced by the voltage recovery after the first grid fault may be superposed on the stator natural flux produced...... by the second grid fault, so that the transient rotor and stator current and torque fluctuations under the second grid fault may be influenced by the characteristic of the first grid fault, including the voltage dips level and the grid fault angle, as well as the duration between two faults. The mathematical...

  8. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators.

    Science.gov (United States)

    Manonmani, N; Subbiah, V; Sivakumar, L

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  9. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    N. Manonmani

    2015-01-01

    Full Text Available The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs. The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  10. Novel scheme for enhancement of fault ride-through capability of doubly fed induction generator based wind farms

    International Nuclear Information System (INIS)

    Vinothkumar, K.; Selvan, M.P.

    2011-01-01

    Research highlights: → Proposed Fault ride-through (FRT) scheme for DFIG is aimed at energy conservation. → The input mechanical energy is stored during fault and utilized at fault clearance. → Enhanced Rotor speed stability of DFIG. → Reduced Reactive power requirement and rapid voltage recovery at fault clearance. → Improved post fault performance of DFIG at fault clearance. -- Abstract: Enhancement of fault ride-through (FRT) capability and subsequent improvement of rotor speed stability of wind farms equipped with doubly fed induction generator (DFIG) is the objective of this paper. The objective is achieved by employing a novel FRT scheme with suitable control strategy. The proposed FRT scheme, which is connected between the rotor circuit and dc link capacitor in parallel with Rotor Side Converter, consists of an uncontrolled rectifier, two sets of IGBT switches, a diode and an inductor. In this scheme, the input mechanical energy of the wind turbine during grid fault is stored and utilized at the moment of fault clearance, instead of being dissipated in the resistors of the crowbar circuit as in the existing FRT schemes. Consequently, torque balance between the electrical and mechanical quantities is achieved and hence the rotor speed deviation and electromagnetic torque fluctuations are reduced. This results in reduced reactive power requirement and rapid reestablishment of terminal voltage on fault clearance. Furthermore, the stored electromagnetic energy in the inductor is transferred into the dc link capacitor on fault clearance and hence the grid side converter is relieved from charging the dc link capacitor, which is very crucial at this moment, and this converter can be utilized to its full capacity for rapid restoration of terminal voltage and normal operation of DFIG. Extensive simulation study carried out employing PSCAD/EMTDC software vividly demonstrates the potential capabilities of the proposed scheme in enhancing the performance of

  11. Novel scheme for enhancement of fault ride-through capability of doubly fed induction generator based wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Vinothkumar, K. [Department of Electrical and Electronics Engineering, National Institute of Technology, Tiruchirappalli, Tamilnadu 620015 (India); Selvan, M.P., E-mail: selvanmp@nitt.ed [Department of Electrical and Electronics Engineering, National Institute of Technology, Tiruchirappalli, Tamilnadu 620015 (India)

    2011-07-15

    Research highlights: {yields} Proposed Fault ride-through (FRT) scheme for DFIG is aimed at energy conservation. {yields} The input mechanical energy is stored during fault and utilized at fault clearance. {yields} Enhanced Rotor speed stability of DFIG. {yields} Reduced Reactive power requirement and rapid voltage recovery at fault clearance. {yields} Improved post fault performance of DFIG at fault clearance. -- Abstract: Enhancement of fault ride-through (FRT) capability and subsequent improvement of rotor speed stability of wind farms equipped with doubly fed induction generator (DFIG) is the objective of this paper. The objective is achieved by employing a novel FRT scheme with suitable control strategy. The proposed FRT scheme, which is connected between the rotor circuit and dc link capacitor in parallel with Rotor Side Converter, consists of an uncontrolled rectifier, two sets of IGBT switches, a diode and an inductor. In this scheme, the input mechanical energy of the wind turbine during grid fault is stored and utilized at the moment of fault clearance, instead of being dissipated in the resistors of the crowbar circuit as in the existing FRT schemes. Consequently, torque balance between the electrical and mechanical quantities is achieved and hence the rotor speed deviation and electromagnetic torque fluctuations are reduced. This results in reduced reactive power requirement and rapid reestablishment of terminal voltage on fault clearance. Furthermore, the stored electromagnetic energy in the inductor is transferred into the dc link capacitor on fault clearance and hence the grid side converter is relieved from charging the dc link capacitor, which is very crucial at this moment, and this converter can be utilized to its full capacity for rapid restoration of terminal voltage and normal operation of DFIG. Extensive simulation study carried out employing PSCAD/EMTDC software vividly demonstrates the potential capabilities of the proposed scheme in

  12. Modeling and Comparison of Power Converters for Doubly Fed Induction Generators in Wind Turbines

    DEFF Research Database (Denmark)

    Helle, Lars

    on the generated power quality and controllability. A consequence of this increased focus has been an ever increased set of requirements formulated in national grid requirement. These requirements has forced wind turbines to evolve from a simple generator on a stick into complicated miniature power plants......During the last decades, renewable energy resources have become an ever increasing part of the world wide power generation and especially energy produced by wind turbines has captured a significant part of this power production. This large penetration of wind power has caused increased focus...... on the design engineers employed in the wind industry. Such a progress may force design engineers to adopt common practice from more or less related technologies rather than finding the optimum solution for the specific application. For instance when applying power electronic converters to wind turbines...

  13. Mission profile resolution effects on lifetime estimation of doubly-fed induction generator power converter

    DEFF Research Database (Denmark)

    Zhang, Guanguan; Zhou, Dao; Blaabjerg, Frede

    2017-01-01

    , and the corresponding thermal modeling of power semiconductors are discussed. Accordingly, effects of different mission profiles on the consumed lifetime of the power converter are evaluated. In the above three thermal cycles, the IGBT of the grid-side converter and the diode of the rotor-side converter are more...... fragile, and the total consumed lifetimes are higher. Moreover, the short-term thermal cycles with milliseconds resolution induce the unbalance of the lifetime between the diode and IGBT of the grid-side converter, while thermal cycles with hour, second, and millisecond resolution consumes the similar......In the wind energy generation system, mission profiles are complicated, which range from seconds to years. In order to estimate the consumed lifetime of the power converter, wind speed profiles with the time resolution of 1 hour, 1 second and 0.5 millisecond are studied in this paper...

  14. Voltage Control in Wind Power Plants with Doubly Fed Generators

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez

    In this work, the process of designing a wind power plant composed of; doubly fed induction generators, a static compensator unit, mechanically switched capacitors and on-load tap changer, for voltage control is shown. The selected control structure is based on a decentralized system, since...... supplied by the doubly fed induction generator wind turbines is overcome by installing a reactive power compensator, i.e. a static compensator unit, which is coordinated with the plant control by a specific dispatcher. This dispatcher is set according to the result of the wind power plant load flow....... To release the operation of the converters during steady-state disturbances, mechanically switched capacitors are installed in the wind power plant, which due to their characteristics, they are appropriate for permanent disturbances compensation. The mechanically switched capacitors are controlled to allow...

  15. Improvement of small-signal stability of power system by controlling doubly fed induction generators of a large-capacity wind farm

    Directory of Open Access Journals (Sweden)

    Tomohiro Adachi

    2016-01-01

    Full Text Available Many wind turbine generations have been installed into power systems around the world, where in recent years doubly fed induction generator (DFIG attracts a lot of attentions because of its efficiency and controllability. However, the DFIG is connected to the power system through inverters and originally does not have an ability to release the kinetic energy of the rotor or resorb the surplus power of the power system as the kinetic energy. Therefore, it has not been made clear how the DFIGs have an influence on small-signal stability in power systems. In this paper, we propose a control scheme of the DFIG and analyse its effect on the small-signal stability of the power system by eigenvalue calculations and time-domain simulations.

  16. A solar PV augmented hybrid scheme for enhanced wind power generation through improved control strategy for grid connected doubly fed induction generator

    Directory of Open Access Journals (Sweden)

    Adikanda Parida

    2016-12-01

    Full Text Available In this paper, a wind power generation scheme using a grid connected doubly fed induction generator (DFIG augmented with solar PV has been proposed. A reactive power-based rotor speed and position estimation technique with reduced machine parameter sensitivity is also proposed to improve the performance of the DFIG controller. The estimation algorithm is based on model reference adaptive system (MRAS, which uses the air gap reactive power as the adjustable variable. The overall generation reliability of the wind energy conversion system can be considerably improved as both solar and wind energy can supplement each other during lean periods of either of the sources. The rotor-side DC-link voltage and active power generation at the stator terminals of the DFIG are maintained constant with minimum storage battery capacity using single converter arrangement without grid-side converter (GSC. The proposed scheme has been simulated and experimentally validated with a practical 2.5 kW DFIG using dSPACE CP1104 module which produced satisfactory results.

  17. A New Current Control Strategy of Maximizing The Generated Power From a Doubly Fed Induction Generator System

    DEFF Research Database (Denmark)

    Li, Hui; Chen, Zhe

    2006-01-01

    Switched reluctance generator (SR Generator) has various desirable features which include simple and solid structure, easiness of maintenance, small moment of rotor inertia and low cost. However, the SR generator has not been put into practical use widely because an optimum design of SR generator...... is consist of half number of switching devices for the AHBC. The operating characteristics of the SR generators were discussed based on FEM analysis and experiments....

  18. Real-time simulation of a Doubly-Fed Induction Generator based wind power system on eMEGASimRTM Real-Time Digital Simulator

    Science.gov (United States)

    Boakye-Boateng, Nasir Abdulai

    The growing demand for wind power integration into the generation mix prompts the need to subject these systems to stringent performance requirements. This study sought to identify the required tools and procedures needed to perform real-time simulation studies of Doubly-Fed Induction Generator (DFIG) based wind generation systems as basis for performing more practical tests of reliability and performance for both grid-connected and islanded wind generation systems. The author focused on developing a platform for wind generation studies and in addition, the author tested the performance of two DFIG models on the platform real-time simulation model; an average SimpowerSystemsRTM DFIG wind turbine, and a detailed DFIG based wind turbine using ARTEMiSRTM components. The platform model implemented here consists of a high voltage transmission system with four integrated wind farm models consisting in total of 65 DFIG based wind turbines and it was developed and tested on OPAL-RT's eMEGASimRTM Real-Time Digital Simulator.

  19. Fuzzy logic based power management strategy of a multi-MW doubly-fed induction generator wind turbine with battery and ultracapacitor

    International Nuclear Information System (INIS)

    Sarrias-Mena, Raúl; Fernández-Ramírez, Luis M.; García-Vázquez, Carlos Andrés; Jurado, Francisco

    2014-01-01

    Integrating energy storage systems (ESS) with wind turbines results to be an interesting option for improving the grid integration capability of wind energy. This paper presents and evaluates a wind hybrid system consisting of a 1.5 MW doubly-fed induction generator (DFIG) wind turbine and double battery-ultracapacitor ESS. Commercially available components are used in this wind hybrid system. A novel supervisory control system (SCS) is designed and implemented, which is responsible for setting the active and reactive power references for each component of the hybrid system. A fuzzy logic controller, taking into account the grid demand, power generation prediction, actual DFIG power generation and state-of-charge (SOC) of the ESSs, sets the active power references. The reactive power references are proportionally delivered to each element regarding their current limitations in the SCS. The appropriate control of the power converters allows each power source to achieve the operation defined by the SCS. The wind hybrid system and SCS are assessed by simulation under wind fluctuations, grid demand changes, and grid disturbances. Results show an improved performance in the overall response of the system with the implementation of the SCS. - Highlights: • We study a wind hybrid system based on DFIG wind turbine, battery and ultracapacitor. • A novel supervisory control system based on fuzzy logic is designed and implemented. • The control improves the system response under different operating conditions

  20. Direct Flux Control for Stand-Alone Operation Brushless Doubly Fed Induction Generators Using a Resonant-Based Sliding-Mode Control Approach

    Directory of Open Access Journals (Sweden)

    Kai Ji

    2018-04-01

    Full Text Available In this paper, a novel voltage control strategy for stand-alone operation brushless doubly fed induction generators for variable speed constant frequency wind energy conversion systems was presented and discussed. Based on the model of the power generation system, the proposed direct flux control strategy employs a nonlinear reduced-order generalized integrator-based resonant sliding-mode control approach to directly calculate and regulate the output value of converter which the control winding stator requires so as to eliminate its instantaneous errors, without involving any synchronous rotating coordinate transformations. The stability, robustness and convergence capability of the proposed control strategy were described and analyzed. Owing to the fact no additional current control inner loops are involved, the system configuration is therefore simplified and the dynamic performance enhanced. A constant converter switching frequency was achieved by using space vector pulse width modulation, which reduces the harmonics of the generator terminal voltage. In addition, the feasibility and validity of the proposed scheme is verified by experiments, and excellent steady and transient performance is achieved.

  1. Real-Time Control of Active and Reactive Power for Doubly Fed Induction Generator (DFIG-Based Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Aman Abdulla Tanvir

    2015-09-01

    Full Text Available This paper presents the modeling, rapid control prototyping, and hardware-in-the-loop testing for real-time simulation and control of a grid-connected doubly fed induction generator (DFIG in a laboratory-size wind turbine emulator for wind energy conversation systems. The generator is modeled using the direct-quadrature rotating reference frame circuit along with the aligned stator flux, and the field-oriented control approach is applied for independent control of the active and reactive power and the DC-link voltage at the grid side. The control of the active, reactive power and the DC-link voltage are performed using a back-to-back converter at sub- and super-synchronous as well as at variable speeds. The control strategy is experimentally validated on an emulated wind turbine driven by the Opal-RT real-time simulator (OP5600 for simultaneous control of the DC-link voltage, active and reactive power.

  2. A Short-Term Outage Model of Wind Turbines with Doubly Fed Induction Generators Based on Supervisory Control and Data Acquisition Data

    Directory of Open Access Journals (Sweden)

    Peng Sun

    2016-10-01

    Full Text Available This paper presents a short-term wind turbine (WT outage model based on the data collected from a wind farm supervisory control and data acquisition (SCADA system. Neural networks (NNs are used to establish prediction models of the WT condition parameters that are dependent on environmental conditions such as ambient temperature and wind speed. The prediction error distributions are discussed and used to calculate probabilities of the operation of protection relays (POPRs that were caused by the threshold exceedance of the environmentally sensitive parameters. The POPRs for other condition parameters are based on the setting time of the operation of protection relays. The union probability method is used to integrate the probabilities of operation of each protection relay to predict the WT short term outage probability. The proposed method has been used for real 1.5 MW WTs with doubly fed induction generators (DFIGs. The results show that the proposed method is more effective in WT outage probability prediction than traditional methods.

  3. Effect of Short-Circuit Faults in the Back-to-Back Power Electronic Converter and Rotor Terminals on the Operational Behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Dimitrios G. Giaourakis

    2015-02-01

    Full Text Available This paper deals with the operational behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System under power electronic converter and rotor terminals faulty conditions. More specifically, the effect of the short-circuit fault both in one IGBT of the back-to-back power electronic converter and in rotor phases on the overall system behavior has been investigated via simulation using a system of 2 MW. Finally, the consequences of these faults have been evaluated.

  4. Modeling, analysis, control and design application guidelines of Doubly Fed Induction Generator (DFIG) for wind power applications

    Science.gov (United States)

    Masaud, Tarek

    Double Fed Induction Generators (DFIG) has been widely used for the past two decades in large wind farms. However, there are many open-ended problems yet to be solved before they can be implemented in some specific applications. This dissertation deals with the general analysis, modeling, control and applications of the DFIG for large wind farm applications. A detailed "d-q" model of DFIG along with other applications is simulated using the MATLAB/Simulink platform. The simulation results have been discussed in detail in both sub-synchronous and super-synchronous mode of operation. An improved vector control strategy based on the rotor flux oriented vector control has been proposed to control the active power output of the DFIG. The new vector control strategy is compared with the stator flux oriented vector control which is commonly used. It is observed that the new improved vector control method provides a better active power tracking accuracy compare with the stator flux oriented vector control. The behavior of the DFIG -based wind farm under the various grid disturbances is also studied in this dissertation. The implementation of the Flexible AC Transmission System devices (FACTS) to overcome the voltage stability issue for such applications is investigated. The study includes the implementation of both a static synchronous compensator (STATCOM), and the static VAR compensator (SVC) as dynamic reactive power compensators at the point of common coupling to support DFIG-based wind farm during disturbances. Integrating FACTS protect the grid connected DFIG-based wind farm from going offline during and after the disturbances. It is found that the both devices improve the transient performance and therefore helps the wind turbine generator system to remain in service during grid faults. A comparison between the performance of the two devices in terms of the amount of reactive power injected, time response and the application cost has been discussed in this

  5. A novel transient rotor current control scheme of a doubly-fed induction generator equipped with superconducting magnetic energy storage for voltage and frequency support

    Science.gov (United States)

    Shen, Yang-Wu; Ke, De-Ping; Sun, Yuan-Zhang; Daniel, Kirschen; Wang, Yi-Shen; Hu, Yuan-Chao

    2015-07-01

    A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator (DFIG) equipped with a superconducting magnetic energy storage (SMES) device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter (GSC) is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter (RSC) has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive (priority) and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method. Project supported by the National Natural Science Foundation of China (Grant No. 51307124) and the Major Program of the National Natural Science Foundation of China (Grant No. 51190105).

  6. Response of MV-connected Doubly-Fed Induction Generator Wind Turbines and CHP plants to Grid Disturbances

    NARCIS (Netherlands)

    Karaliolios, P.; Slootweg, J.G.; Kling, W.L.

    2010-01-01

    Notwithstanding the positive environmental impact, the increasing penetration of Distributed Generation (DG) units connected to the distribution network raises new topics concerning the expected response of these during outages. Grid disturbances especially at the transmission level can cause the

  7. Contribution to the control of doubly-fed induction generators in wind power plants with particular consideration of asymmetrical grid conditions

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Marlies

    2012-06-21

    In the study presented here, four different control strategies for the control of the inverter currents of a doubly-fed induction generator (DFIG) system are analysed and evaluated by means of simulation using Matlab/Simulink registered. Special attention is paid to the behaviour of the generator during asymmetrical grid voltage dips. Different control schemes are employed to reduce torque and DC-link voltage oscillations and the resulting additional loads on the system during such dips. The field-oriented control (FOC) scheme is the one usually deployed for the control of DFIGs in wind power plants and is used as the reference system within this study. The inverter currents (of the rotor-side inverter and the grid-side inverter) are regulated by proportional-integral controllers (PI) in a rotating coordinate system in which they are represented by dq-components. These components are direct quantities. A positive-negative-sequence current control (PNC) strategy is used to control the positive-sequence currents and the negative-sequence currents separately in two contra-rotating coordinate systems using PI-controllers. In contrast to the first two control strategies, frequency-selective current controllers (FSC) serve to regulate the currents in a static coordinate system. In this case the currents are represented by {alpha}{beta}-components which are alternating quantities. Combining the FSC and PNC strategies will produce frequencyselective positive-negative-sequence current controllers (FSC(PN)). These control the currents in a static coordinate system. The currents are represented by alternating {alpha}{beta}-components as in frequency-selective control but separate reference values for the negative-sequence currents are provided as in positive-negative-sequence control. Theoretical reasoning suggests and simulations prove that the three proposed alternative control strategies can improve the behaviour of DFIG-systems during slight asymmetries in the grid

  8. Modeling of wind turbines with doubly fed generator system

    CERN Document Server

    Fortmann, Jens

    2014-01-01

    Jens Fortmann describes the deduction of models for the grid integration of variable speed wind turbines and the reactive power control design of wind plants. The modeling part is intended as background to understand the theory, capabilities and limitations of the generic doubly fed generator and full converter wind turbine models described in the IEC 61400-27-1 and as 2nd generation WECC models that are used as standard library models of wind turbines for grid simulation software. Focus of the reactive power control part is a deduction of the origin and theory behind the reactive current requ

  9. Performance of Doubly-Fed Wind Power Generators During Voltage Dips

    DEFF Research Database (Denmark)

    Aparicio, N.; Chen, Zhe; Beltran, H.

    The growing of wind generation in Spain has forced its Transmission System Operator (TSO) to release new requirements that establish the amount of reactive power that a wind turbine has to supply to the grid during a voltage dip. Wind turbines equipped with doubly-fed induction generators (DFIG......) can regulate easily the reactive power generated in steady state. However, difficulties appear when reactive power has to be generated during voltage dips. Simulations have been carried out in order to check whether DFIG wind turbines can fulfill the reactive power requirements. Protection system...... commonly employed with DFIG in order to achieve ride-through capabilities including crowbar plays an important role to meet the requirements together with grid-side converter. Resistance associated with the crowbar and its connection duration are crucial at the beginning of the fault. Grid-side converter...

  10. 双馈风电机组与高速永磁风电机组对比分析﹡%Comparison of Doubly-fed Induction Generator and High Speed Permanent Magnet Wind Power Generator

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    is paper compared two main wind turbines. One is doubly-fed induction generator, the other is high speed permanent magnet wind power generator. It calculated the efficiency and annual electric energy production in different IEC wind classes, and compared the cost based on the market value. A er analyzing the reliability, e ciency and power grid adaptability, it came to the conclusion that two types of wind turbines have di erent advantages and meet di erent requirements from customers. erefore, development of two types of wind turbines will be be er adapted to the market competition.%  本文从风电机组角度对两种主流的发电方式,即双馈式发电机组和高速永磁发电机组,进行了对比分析。计算了两种发电方式的效率及在不同风区的年发电量,根据市场价格对各部件进行成本对比。在综合考虑了可靠性、效率、电网适应性等方面后指出,两种方式各有特点,适合客户的不同需求。因此,作为风电机组开发商,同时开发两种机型方能更好地适应市场的竞争。

  11. Performance Analysis of a Four-Switch Three-Phase Grid-Side Converter with Modulation Simplification in a Doubly-Fed Induction Generator-Based Wind Turbine (DFIG-WT with Different External Disturbances

    Directory of Open Access Journals (Sweden)

    Kai Ni

    2017-05-01

    Full Text Available This paper investigates the performance of a fault-tolerant four-switch three-phase (FSTP grid-side converter (GSC in a doubly-fed induction generator-based wind turbine (DFIG-WT. The space vector pulse width modulation (SVPWM technique is simplified and unified duty ratios are used for controlling the FSTP GSC. Steady DC-bus voltage, sinusoidal three-phase grid currents and unity power factor are obtained. In addition, the balance of capacitor voltages is accomplished based on the analysis of current flows at the midpoint of DC bus in different operational modes. Besides, external disturbances such as fluctuating wind speed and grid voltage sag are considered to test its fault-tolerant ability. Furthermore, the effects of fluctuating wind speed on the performance of DFIG-WT system are explained according to an approximate expression of the turbine torque. The performance of the proposed FSTP GSC is simulated in Matlab/Simulink 2016a based on a detailed 1.5 MW DFIG-WT Simulink model. Experiments are carried out on a 2 kW platform by using a discrete signal processor (DSP TMS320F28335 controller to validate the reliability of DFIG-WT for the cases with step change of the stator active power and grid voltage sag, respectively.

  12. Simultaneous Robust Coordinated Damping Control of Power System Stabilizers (PSSs, Static Var Compensator (SVC and Doubly-Fed Induction Generator Power Oscillation Dampers (DFIG PODs in Multimachine Power Systems

    Directory of Open Access Journals (Sweden)

    Jian Zuo

    2017-04-01

    Full Text Available The potential of utilizing doubly-fed induction generator (DFIG-based wind farms to improve power system damping performance and to enhance small signal stability has been proposed by many researchers. However, the simultaneous coordinated tuning of a DFIG power oscillation damper (POD with other damping controllers is rarely involved. A simultaneous robust coordinated multiple damping controller design strategy for a power system incorporating power system stabilizer (PSS, static var compensator (SVC POD and DFIG POD is presented in this paper. This coordinated damping control design strategy is addressed as an eigenvalue-based optimization problem to increase the damping ratios of oscillation modes. Both local and inter-area electromechanical oscillation modes are intended in the optimization design process. Wide-area phasor measurement unit (PMU signals, selected by the joint modal controllability/ observability index, are utilized as SVC and DFIG POD feedback modulation signals to suppress inter-area oscillation modes. The robustness of the proposed coordinated design strategy is achieved by simultaneously considering multiple power flow situations and operating conditions. The recently proposed Grey Wolf optimizer (GWO algorithm is adopted to efficiently optimize the parameter values of multiple damping controllers. The feasibility and effectiveness of the proposed coordinated design strategy are demonstrated through frequency-domain eigenvalue analysis and nonlinear time-domain simulation studies in two modified benchmark test systems. Moreover, the dynamic response simulation results also validate the robustness of the recommended coordinated multiple damping controllers under various system operating conditions.

  13. Single-Electrical-Port Control of Cascaded Doubly-Fed Induction Machine for EV/HEV Applications

    DEFF Research Database (Denmark)

    Han, Peng; Cheng, Ming; Chen, Zhe

    2017-01-01

    A single-electrical-port control scheme, for four-quadrant operation of cascaded doubly-fed induction machine (CDFIM), which has long been conceived as a motor or generator only suitable for limited two-quadrant operation, is proposed and theoretically demonstrated. The drive system is configured...... as slave inverter. With this configuration, the control emphasis is placed on the slave inverter, yielding reduced control complexity and cost, and the inaccuracy of flux estimation in conventional FOC for singly-fed induction machines is avoided at very low or even zero speed. It is found that the doubly...

  14. Análisis y modelado del generador de inducción doblemente alimentado. Analysis and Modeling of Doubly Fed Induction Generators.

    Directory of Open Access Journals (Sweden)

    Lesyani T. León Viltre

    2015-04-01

    Full Text Available Uno de los generadores eólicos de velocidad variable más utilizados en la actualidad es el generador de inducción doblemente alimentado (DFIG. En el presente trabajo se presenta un esquema de control del DFIG. El convertidor de potencia del lado de la red es modelado y controlado usando el vector de tensión orientado a los ejes dq, lo que garantiza que con la componente del eje d de la corriente se pueda controlar la potencia activa y, por consiguiente, la tensión del bus DC. La componente del eje q es forzada a cero para mantener un factor de potencia unitario. En el convertidor del lado del rotor se utiliza un control orientado al flujo del estator. Para la sincronización con la red se utiliza un método novedoso basado en el método GDSC-PLL (Generalizad delayed signal cancellation. Además, se presenta un análisis del comportamiento del DFIG, ante huecos de tensión.  One of the variable speed wind turbines most commonly used today is the doubly feed induction generator(DFIG.A control scheme of DFIG is discussed in this paper. The power converter connected to the grid side (bus is modeled and controlled using voltage vectororiented dq reference frame, whichguarantees that the active power can be controlled by the daxiscurrent component and consequently the DC bus voltage. The qaxis component is forced to be zero in order to ensurethe unitary power factor. Astator flux oriented control in the rotor circuit converter is used.A novel GDSC-PLL method is used in order to achieve an efficient synchronization with the grid.Onthe order hand, this paper presents an analysis about the DFIG (Double Feed Induction Generator behavior during voltages sags.

  15. Análisis y modelado del generador de inducción doblemente alimentado; Analysis and Modeling of Doubly Fed Induction Generators

    Directory of Open Access Journals (Sweden)

    Lesyani T- León Viltre

    2014-06-01

    Full Text Available Uno de los generadores eólicos de velocidad variable más utilizados en la actualidad es el generador de inducción doblemente alimentado (DFIG. En el presente trabajo se presenta un esquema de control del DFIG. El convertidor de potencia del lado de la red es modelado y controlado usando el vector de tensión orientado a los ejes dq, lo que garantiza que con la componente del eje d de la corriente se pueda controlar la potencia activa y, por consiguiente, la tensión del bus DC. La componente del eje q es forzada a cero para mantener un factor de potencia unitario. En el convertidor del lado del rotor se utiliza un control orientado al flujo del estator. Para la sincronización con la red se utiliza un método novedoso basado en el método GDSC-PLL (Generalizad delayed signal cancellation. Además, se presenta un análisis del comportamiento del DFIG, ante huecos de tensión. One of the variable speed wind turbines most commonly used today is the doubly feed induction generator(DFIG.A control scheme of DFIG is discussed in this paper. The power converter connected to the grid side (bus is modeled and controlled using voltage vectororiented dq reference frame, whichguarantees that the active power can be controlled by the daxiscurrent component and consequently the DC bus voltage. The qaxis component is forced to be zero in order to ensurethe unitary power factor. Astator flux oriented control in the rotor circuit converter is used.A novel GDSC-PLL method is used in order to achieve an efficient synchronization with the grid.Onthe order hand, this paper presents an analysis about the DFIG (Double Feed Induction Generator behavior during voltages sags

  16. A New Vector Control of Brushless Doubly-Fed Inductor Generator With Transient Current Compensation for Stand-Alone Power Generation Applications

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Yu, Kailiang

    2018-01-01

    The stand-alone brushless doubly-fed induction generator (BDFIG) with the conventional control strategies suffers heavily from poor dynamic performance especially under heavy load disturbance. This paper presents a new vector control strategy of BDFIG for stand-alone power generation applications...... control strategies, and the results verify the satisfactory dynamic performance of the proposed strategy....

  17. Control Demonstration of Multiple Doubly-Fed Induction Motors for Hybrid Electric Propulsion

    Science.gov (United States)

    Sadey, David J.; Bodson, Marc; Csank, Jeffrey T.; Hunker, Keith R.; Theman, Casey J.; Taylor, Linda M.

    2017-01-01

    The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application.The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application. DFIMs are attractive for several reasons, including but not limited to the ability to self-start, ability to operate sub- and super-synchronously, and requiring only fractionally rated power converters on a per-unit basis depending on the required range of operation. The focus of this paper is based specifically on the presentation and analysis of a novel strategy which allows for independent operation of each of the aforementioned doubly-fed induction motors. This strategy includes synchronization, soft-start, and closed loop speed control of each motor as a means of controlling output thrust; be it concurrently or differentially. The demonstration of this strategy has recently been proven out on a low power test bed using fractional horsepower machines. Simulation and hardware test results are presented in the paper.

  18. Multifrequency spiral vector model for the brushless doubly-fed induction machine

    DEFF Research Database (Denmark)

    Han, Peng; Cheng, Ming; Zhu, Xinkai

    2017-01-01

    This paper presents a multifrequency spiral vector model for both steady-state and dynamic performance analysis of the brushless doubly-fed induction machine (BDFIM) with a nested-loop rotor. Winding function theory is first employed to give a full picture of the inductance characteristics...... analytically, revealing the underlying relationship between harmonic components of stator-rotor mutual inductances and the airgap magnetic field distribution. Different from existing vector models, which only model the fundamental components of mutual inductances, the proposed vector model takes...... into consideration the low-order space harmonic coupling by incorporating nonsinusoidal inductances into modeling process. A new model order reduction approach is then proposed to transform the nested-loop rotor into an equivalent single-loop one. The effectiveness of the proposed modelling method is verified by 2D...

  19. Analysis of doubly-fed induction machine operating at motoring mode subjected to voltage sag

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-09-01

    Full Text Available Variable Speed (VS Pumped Storage Plants (PSP equipped with large asynchronous (Doubly-Fed Induction machines are emerging now in hydropower applications. Motoring mode of operation of Doubly-Fed Induction Machine (DFIM is essential and techno-economical in this application due to: (1 its uniqueness in active power controllability, (2 bulk power handing capability with less rated power converters in rotor circuit, and (3 integrating Renewable Energy Sources (RES. This paper investigates the performance of two DFIMs at different power ratings (2.2 kW and 2 MW under voltage sag with different attribute. The test results are analyzed in terms of the peaks in torque, speed, power taken and transient currents in rotor and stator circuits. During sag, stable region for DFIM operation along with speed and stator side reactive power input control is also illustrated. The negative effects of voltage sag are briefly discussed. MATLAB simulation is validated with experimentation. The various observations during simulation and experimental analysis are also supported by the theoretical explanations.

  20. Sensorless direct voltage control of the stand-alone brushless doubly-fed generator

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Xiong, Fei

    2017-01-01

    The conventional stand-alone brushless doubly-fed generator (BDFG) control strategies need the feedback from the rotor position or speed sensors, which can reduce system reliability and increase the cost and axial volume of the machine. In this paper, a sensorless direct voltage control (DVC) str......) strategy is presented for the stand-alone BDFG. The satisfactory dynamic performance is verified by experimental results under four kinds of typical operation conditions. Besides, the proposed control strategy is robust due to no generator parameters being required....

  1. Modeling of the wind turbine with doubly fed induction machine and its dynamic behavior in distribution networks

    International Nuclear Information System (INIS)

    Mendez Rodriguez, Christian; Badilla Solorzano, Jorge Adrian

    2014-01-01

    Wind turbines equipped with doubly fed induction generator (DFIG) are described. A model is constructed to represent the behavior of wind turbines during the connection with distribution networks. The main systems that compose a wind turbine with DFIG are specified to develop a mathematical model of each of them. The behavior of the wind turbine in the stable and transient regimes is investigated to explain its dynamics during nominal operation and contingency situations when they are connected to distribution networks. In addition, strategies to mitigate the negative effects of such situations and control strategies to contribute to the dynamics of the network are included. An integrated model of the parts of the wind turbine is built in the program SIMULINK® of MATLAB® to validate the models of the systems and to obtain a tool that allows their simulation. The wind turbine model developed is simulated in order to evaluate and to analyze the dynamic behavior under different operating conditions. The results from validations have revealed an adequate behavior for the model under normal operating conditions. In the case of behavior in contingency situations, the study is limited to the response to three-phase faults and voltage variations, and frequency under conditions of balance in the power system [es

  2. A Flywheel Energy Storage System Based on a Doubly Fed Induction Machine and Battery for Microgrid Control

    Directory of Open Access Journals (Sweden)

    Thai-Thanh Nguyen

    2015-06-01

    Full Text Available Microgrids are eco-friendly power systems because they use renewable sources such as solar and wind power as the main power source. However, the stochastic nature of wind and solar power is a considerable challenge for the efficient operation of microgrids. Microgrid operations have to satisfy quality requirements in terms of the frequency and voltage. To overcome these problems, energy storage systems for short- and long-term storage are used with microgrids. Recently, the use of short-term energy storage systems such as flywheels has attracted significant interest as a potential solution to this problem. Conventional flywheel energy storage systems exhibit only one control mode during operation: either smoothing wind power control or frequency control. In this paper, we propose a new flywheel energy storage system based on a doubly fed induction machine and a battery for use with microgrids. The new flywheel energy storage system can be used not only to mitigate wind power fluctuations, but also to control the frequency as well as the voltage of the microgrid during islanded operation. The performance of the proposed flywheel energy storage system is investigated through various simulations using MATLAB/Simulink software. In addition, a conventional flywheel energy storage system based on a doubly fed induction machine is simulated and its performance compared with that of the proposed one.

  3. Rectifier Fault Diagnosis and Fault Tolerance of a Doubly Fed Brushless Starter Generator

    Directory of Open Access Journals (Sweden)

    Liwei Shi

    2015-01-01

    Full Text Available This paper presents a rectifier fault diagnosis method with wavelet packet analysis to improve the fault tolerant four-phase doubly fed brushless starter generator (DFBLSG system reliability. The system components and fault tolerant principle of the high reliable DFBLSG are given. And the common fault of the rectifier is analyzed. The process of wavelet packet transforms fault detection/identification algorithm is introduced in detail. The fault tolerant performance and output voltage experiments were done to gather the energy characteristics with a voltage sensor. The signal is analyzed with 5-layer wavelet packets, and the energy eigenvalue of each frequency band is obtained. Meanwhile, the energy-eigenvalue tolerance was introduced to improve the diagnostic accuracy. With the wavelet packet fault diagnosis, the fault tolerant four-phase DFBLSG can detect the usual open-circuit fault and operate in the fault tolerant mode if there is a fault. The results indicate that the fault analysis techniques in this paper are accurate and effective.

  4. Dual-Electrical-Port Control of Cascaded Doubly-Fed Induction Machine for EV/HEV Applications

    DEFF Research Database (Denmark)

    Han, Peng; Cheng, Ming; Chen, Zhe

    2017-01-01

    that of the power machine in singly-fed operation mode, and only a half of that of the power machine in doubly-fed operation mode, which shows the urgent need for torque density enhancement of brushless doubly-fed machines for electric vehicle/hybrid electric vehicle applications. Computer simulations...

  5. Effects of wake effect and time delay on output characteristics of doubly fed induction generators in wind power plant%尾流效应和时滞对双馈机组风电场输出特性的影响

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      由于双馈机组已成为国内主流机型且大型双馈机组风电场通常占地面积比较大,需要研究双馈风电机组间的尾流效应及时滞对双馈机组风电场的并网点输出特性的影响情况。通过搭建了30台2 MW双馈风电机组组成的风电场模型,对风速波动和电网故障下双馈机组风电场输出特性进行分析和比较。通过仿真表明,机组间的尾流效应导致双馈机组风电场的风能损失;风速时滞平缓了风电场输出功率。%Because doubly fed induction generator has become the mainstream type and a large wind power plant usually covers a larger area,the impacts of wake effects among wind turbines and time delay on output characteristics of wind power plant need to be studied. With a wind power plant model composed of thirty 2⁃MW double fed induction generator wind tur⁃bines,the output characteristic of wind power plant under the conditions of wind speed fluctuation and grid faults is analyzed and compared. The simulation results show that the wake effects among wind turbines can cause the wind energy loss of wind farm and the wind speed time delay will smooth the power output of wind farm;wake effects among wind turbines and wind speed time delays needs to be considered when the grid⁃connection stability of wind farms with double fed induction generator wind turbines is analyzed.

  6. Doubly Fed Induction Generator Analysis Through Wavelet Technique

    Directory of Open Access Journals (Sweden)

    M. E. Ekpenyong

    2014-01-01

    Full Text Available Outage probability is a key performance measure for real time traffic in wireless networks and is often considered as more critical than drop call probability. In this paper, we study the outage probability in a wireless mobile environment, where the interferers are distributed on the ground. Taking into consideration the background noise and the cell radius, we formulat e an out age p robabilit y model coup led wit h observed dat a from Airt el Nigeria form ally Z ain Communications Limited, a Telecommunication company operating in Nigeria and simulate the system’s performance using the Java programming language. We also present a geographical information system (GIS solution showing the distribution of signal outages at various base stations in Akwa Ibom State (East region of Nigeria for observed and simulated data. A performance evaluation of these data reveals that our model could greatly improve the system’s performance. The results obtained allow us to study the stability of the network and evaluate the network in a more efficient and accurate manner.

  7. Variable-Speed Generation Subsystem Using the Doubly-Fed Generator; Period of Performance February 9, 1994 - April 30, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, C.H.; Lauw, H.K.; Marckx, D.A. (Electronic Power Conditioning Incorporated)

    2000-12-18

    Over the past decade, fixed-speed, utility-scale wind turbines have technically advanced to a point where they can economically complete against nuclear and fossil-fuel-based power plants in geographical areas with a sufficient wind resource. The objective of this subcontract was to compare various electrical topologies allowing variable-speed turbine operation, identify the most suitable for a 275-kW (or larger) utility-scale wind turbine, and then design, build, lab test, and field test this variable-speed generation subsystem based on the previously identified optimum approach. Preliminary tests of the controls for a doubly fed variable-speed generation system rated at 750 kW were performed on a wind turbine. A 275-kW VSGS was thoroughly tested in the laboratory and on a wind turbine. Using field-oriented control, excellent dynamic behavior of the drive train was demonstrated, acoustic tests revealed an 11 dB reduction in turbine noise in low-wind, low-RPM operation compared to fixed-speed operation. The overall efficiency of the electrical system suffered from inadequate efficiency of the power converter at low power. Consequently, a different converter topology has been proposed that will satisfy both efficiency and power quality requirements for future use. This report provides information on all aspects of the project, including events that were unanticipated at the outset. A great deal of information is available in the references, comprised of NREL reports, journal articles, and conference papers on specific project results.

  8. FUZZY SLIDING MODE CONTROLLER FOR DOUBLY FED ...

    African Journals Online (AJOL)

    2010-12-31

    Dec 31, 2010 ... against internal and external perturbations, but the FSMC is superior to ... controller, doubly fed induction motor, fuzzy logic control. 1. ... capabilities in accounting for modeling imprecision and bounded disturbances. It ..... To show the effect of the parameters uncertainties, we have simulated the system with.

  9. Unbalanced voltage faults: the impact on structural loads of doubly fed asynchronous generator wind turbines

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; Cutululis, Nicolaos Antonio; Hansen, Anca Daniela

    2014-01-01

    This paper investigates the impact that unbalanced voltage faults have on wind turbine structural loads. In such cases, electromagnetic torque oscillations occur at two times the supply voltage frequency. The objectives of this work are to quantify wind turbine structural loads induced...... by unbalanced voltage faults relative to those during normal operation; and to evaluate the potential for reducing structural loads with the control of the generator. The method applied is integrated dynamic analysis. Namely, dynamic analysis with models that consider the most important aeroelastic, electrical...

  10. Maximum Wind Power Tracking of Doubly Fed Wind Turbine System Based on Adaptive Gain Second-Order Sliding Mode

    Directory of Open Access Journals (Sweden)

    Hongchang Sun

    2018-01-01

    Full Text Available This paper proposes an adaptive gain second-order sliding mode control strategy to track optimal electromagnetic torque and regulate reactive power of doubly fed wind turbine system. Firstly, wind turbine aerodynamic characteristics and doubly fed induction generator (DFIG modeling are presented. Then, electromagnetic torque error and reactive power error are chosen as sliding variables, and fixed gain super-twisting sliding mode control scheme is designed. Considering that uncertainty upper bound is unknown and is hard to be estimated in actual doubly fed wind turbine system, a gain scheduled law is proposed to compel control parameters variation according to uncertainty upper bound real-time. Adaptive gain second-order sliding mode rotor voltage control method is constructed in detail and finite time stability of doubly fed wind turbine control system is strictly proved. The superiority and robustness of the proposed control scheme are finally evaluated on a 1.5 MW DFIG wind turbine system.

  11. Investigation of transient models and performances for a doubly fed wind turbine under a grid fault

    DEFF Research Database (Denmark)

    Wang, M.; Zhao, B.; Li, H.

    2011-01-01

    fed induction generator (DFIG), the assessments of the impact on the electrical transient performances were investigated for the doubly fed wind turbine with different representations of wind turbine drive-train dynamics models, different initial operational conditions and different active crowbar...... crowbar on the transient performances of the doubly fed wind turbine were also investigated, with the possible reasonable trip time of crowbar. The investigation have shown that the transient performances are closely correlated with the wind turbine drive train models, initial operational conditions, key...

  12. Control of frequency converters for wind power systems with doubly fed asynchronous generators; Regelung von Frequenzumrichtern fuer Windenergieanlagen mit doppelt gespeistem Asynchrongenerator

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Stephan [Woodward SEG GmbH und Co. KG, Kempen (Germany)

    2007-07-01

    Modern wind energy systems are characterized by an extensive use of power electronics. Using complex converter systems is technically and commercially very attractive as it allows an optimized operation of the wind turbine in regard to efficiency, reduced stress to the drive train due to variable speed and feeding wind power with high quality into the grid. For some years wind energy systems with frequency converter and doubly fed asynchronous generator have the biggest market share. The main requirements from grid codes regarding fault ride through operation will be summarized and enhanced control algorithms for this special type of system will be presented. (orig.)

  13. Non-linear control of a doubly fed induction machine; Commande non-lineaire d'une machine asynchrone a double alimentation

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, P.E.

    2004-12-15

    This study deals with linear and non-linear control strategies applied to the rotation speed feedback of a doubly fed induction machine (DFIM), whose stator and rotor windings are connected to two Pulse Width Modulation voltage source inverters. We choose to distribute the active powers between the stator and the rotor following a certain proportionality ratio. This leads to guarantee, in steady state operation, a stator and rotor angular frequencies sharing. This distribution is initially assured by two shared angular frequencies controllers, and in a second time by the means of the Park transformation angles directly. Two models are established: the first express the currents, and the second is linked with the fluxes. The simulations results of the linear control (field oriented control), and non-linear control (sliding mode control), show a good independence between the main flux and the torque. An experimental validation is also presented. The results presented show the satisfactory DFIM flux control. Special attention is paid to the active power dispatching. (author)

  14. Utility-scale variable-speed wind turbines using a doubly-fed generator with a soft-switching power converter

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, C.H.; Lauw, H.K.; Marckx, D.A. [Electronic Power Conditioning, Inc., Corvallis, OR (United States)

    1996-12-31

    Utility-scale wind turbines operating at variable RPM have been studied for a considerable period of time. Whereas the increase in energy output originally has been considered the principal benefit of variable-speed operation, the ability to tightly control the drive-train torque by electronic means is becoming another very important cost factor, especially for turbine ratings above 500 kilowatts. This cost benefit becomes even more significant as optimum turbine ratings today are approaching (and surpassing) 1 Megawatt. Having identified the benefits for the turbine, the designer is confronted with the task of finding the most cost-effective variable-speed generation system which allows him to make use of the benefits, yet does not introduce well-known electrical problems associated with state-of-the-art variable-speed generator controls, such as drastically reduced generator winding life, excessive harmonics on the utility, and poor utility power factor. This paper will indicate that for high-power (> 500 kW), utility-scale wind turbines a doubly-fed generator system in connection with a soft-switching resonant power converter is the least-cost variable-speed generation system offering all of the desired benefits, yet avoids the introduction of the potential electrical problems stated above. 3 refs., 3 figs., 1 tab.

  15. Maximum power extraction under different vector-control schemes and grid-synchronization strategy of a wind-driven Brushless Doubly-Fed Reluctance Generator.

    Science.gov (United States)

    Mousa, Mohamed G; Allam, S M; Rashad, Essam M

    2018-01-01

    This paper proposes an advanced strategy to synchronize the wind-driven Brushless Doubly-Fed Reluctance Generator (BDFRG) to the grid-side terminals. The proposed strategy depends mainly upon determining the electrical angle of the grid voltage, θ v and using the same transformation matrix of both the power winding and grid sides to ensure that the generated power-winding voltage has the same phase-sequence of the grid-side voltage. On the other hand, the paper proposes a vector-control (power-winding flux orientation) technique for maximum wind-power extraction under two schemes summarized as; unity power-factor operation and minimum converter-current. Moreover, a soft-starting method is suggested to avoid the employed converter over-current. The first control scheme is achieved by adjusting the command power-winding reactive power at zero for a unity power-factor operation. However, the second scheme depends on setting the command d-axis control-winding current at zero to maximize the ratio of the generator electromagnetic-torque per the converter current. This enables the system to get a certain command torque under minimum converter current. A sample of the obtained simulation and experimental results is presented to check the effectiveness of the proposed control strategies. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Doubly Fed Induction Generator System Resonance Active Damping through Stator Virtual Impedance

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    (positive capacitor or negative inductor) into the stator branch through stator current feedforward control. The effectiveness of the DFIG system active damping control is verified by a 7.5 kW experimental down-scaled DFIG system, and simulation results of a commercial 2 MW DFIG system is provided as well....... converters/loads. This paper analyzes and explains first the HFR phenomenon between the DFIG system and a parallel compensated weak network (series RL + shunt C). Then on the basis of the DFIG system impedance modeling, an active damping control strategy is introduced by inserting a virtual impedance...... Frequency Resonance (HFR) due to the impedance interaction between the DFIG system and the weak grid network whose impedance is comparative large. Thus, it is important to implement an active damping for the HFR in order to ensure a safe and reliable operation of both the DFIG system and the grid connected...

  17. An analytic electromagnetic calculation method for performance evolution of doubly fed induction generators for wind turbines

    DEFF Research Database (Denmark)

    Zhang, Wen-juan; Huang, Shou-dao; Chen, Zhe

    2013-01-01

    to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well...

  18. Stator Current Harmonic Control with Resonant Controller for Doubly Fed Induction Generator

    DEFF Research Database (Denmark)

    Liu, Changjin; Blaabjerg, Frede; Chen, Wenjie

    2012-01-01

    rotor current control loop for harmonic suppression. The overall control scheme is implemented in dq frame. Based on a mathematical model of the DFIG control system, the effects on system stability using the resonant controller, an analysis of the steady-state error, and the dynamic performance......, are discussed in this paper. Taking these effects into account, the parameters of the resonant controller can be designed and effectively damp the influence from the grid voltage harmonics. As a result, the impacts of the negative sequence fifth- and positive sequence seventh-order voltage harmonics...... harmonics, especially low-order harmonics. This paper proposes a stator current harmonic suppression method using a sixth-order resonant controller to eliminate negative sequence fifth- and positive sequence seventh-order current harmonics. A stator current harmonic control loop is added to the conventional...

  19. Modeling and analysis of doubly fed induction generator wind energy systems

    CERN Document Server

    Fan, Lingling

    2015-01-01

    Wind Energy Systems: Modeling, Analysis and Control with DFIG provides key information on machine/converter modelling strategies based on space vectors, complex vector, and further frequency-domain variables. It includes applications that focus on wind energy grid integration, with analysis and control explanations with examples. For those working in the field of wind energy integration examining the potential risk of stability is key, this edition looks at how wind energy is modelled, what kind of control systems are adopted, how it interacts with the grid, as well as suitable study

  20. Simulation of Electric Faults in Doubly-Fed Induction Generators Employing Advanced Mathematical Modelling

    DEFF Research Database (Denmark)

    Martens, Sebastian; Mijatovic, Nenad; Holbøll, Joachim

    2015-01-01

    in many areas of electrical machine analysis. However, for fault investigations, the phase-coordinate representation has been found more suitable. This paper presents a mathematical model in phase coordinates of the DFIG with two parallel windings per rotor phase. The model has been implemented in Matlab...

  1. Adaptive Control and Parameter Identification of a Doubly-Fed Induction Generator for Wind Power

    Science.gov (United States)

    2011-09-01

    power. It later hit a plateau during an electricity restructuring period in the 1990s and regained momentum in the past decade [4]. The spread of wind...downstream, the Bernoulli equation states that the total energy of the airflow remains constant. Given that the above conditions are satisfied, one...can apply the Bernoulli equation from far upstream to just in front of the rotor and from just behind the rotor to far downstream [16]: D Dp p V Vρ

  2. Dynamic Droop-Based Inertial Control of a Doubly-Fed Induction Generator

    DEFF Research Database (Denmark)

    Hwang, Min; Muljadi, Eduard; Park, Jung-Wook

    2016-01-01

    based on the ROCOF to release a large amount of kinetic energy during the initial stage of a disturbance. To do this, a shaping function that relates the droop to the ROCOF is used. To achieve the second goal, different shaping functions, which depend on rotor speeds, are used to give a large...

  3. Parameterization of a synchronous generator to represent a doubly fed induction generator with chopper protection for fault studies

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

    2011-01-01

    knowledge of the wind turbine short circuit current contribution is needed for component sizing and protection relay settings during faults within the wind power plant collector system or in the external networks. When studying fault currents and protection settings for wind power installations...

  4. Comparación del comportamiento en la red eléctrica del aerogenerador asincrónico de jaula de ardilla y el doblemente alimentado; Comparison of the Behavior in the Electric Network of the Squirrel Cage Wind Turbine Generator and the Doubly Fed Wind Turbin

    Directory of Open Access Journals (Sweden)

    Mariely Francisco Fernández

    2011-02-01

    Full Text Available En este artículo, se lleva a cabo un análisis comparativo entre estos dos tipos de aerogeneradores. Labase para la comparación es el comportamiento del generador en el sistema sujeto a diferentes tiposperturbaciones tales como: valles de tensión, cortocircuitos, rachas de viento y cambios de carga.Para lasimulación se utiliza el SimPowerSystem del MATLAB. Sus últimas versiones tienen entre sus herramientasmodelos de turbinas y generadores eólicos que facilitan mucho el trabajo.En el caso de los GeneradoresAsincrónicos con Rotor Jaula de ardilla se analizaron tanto el caso de Condensadores Variables enParalelo como la utilización de Compensadores Estáticos de Reactivo. Ésta última permite la regulación dela tensión en el punto de conexión del Aerogenerador. Finalmente, queda demostrada y bien argumentadaen el trabajo la superioridad del generador doblemente alimentado. In this paper, a comparative analysis of these two types of wind turbine generators is made. The base forthe comparison is the behaviour of the generator and the system submitted to different disturbances suchas voltage dips, short-circuits, winds gusts and load changes. The MATLAB SimPowerSystem toolbox isused for doing these analyses. Its last version has a Wind Turbine Generator tool that facilitates the work.In the case of the Cage Induction Generator, a changing paralleled capacitor bank and a static varcompensator are supposed and analyzed. It is demonstrated that the last one is capable of supportnetwork voltage. Finally, the superiority of the Doubly Fed Induction Generator is clearly demonstrated andwell argument. 

  5. Analysis of Unbalanced Magnetic Pull in Wound Rotor Induction Machines using Finite Element Analysis – Transient, Motoring and Generating Modes

    DEFF Research Database (Denmark)

    Dorrell, David G.; Hermann, Alexander Niels August; Jensen, Bogi Bech

    2013-01-01

    eccentricity. The operating conditions are varied so that transient, motoring and doubly-fed induction generator modes are studied. This allows greater understanding of the radial forces involved. Wound rotor induction machines exhibit higher unbalanced magnetic pull than cage induction machines so......There has been much literature on unbalanced magnetic pull in various types of electrical machine. This can lead to bearing wear and additional vibrations in the machine. In this paper a wound rotor induction is studied. Finite element analysis studies are conducted when the rotor has 10 % rotor...

  6. Fuzzy sliding mode controller for doubly fed induction motor speed ...

    African Journals Online (AJOL)

    The use of the nonlinear fuzzy sliding mode method provides very good performance for motor operation and robustness of the control law despite the external/internal perturbations. The chattering effects is eliminated by a particular function "sat" that presents a serious problem to applications of variable structure systems.

  7. Modeling and Design of Brushless Doubly-Fed Induction Machines

    NARCIS (Netherlands)

    Wang, X.

    2017-01-01

    The rapid increase of wind power in the power grid results in high grid connection requirements for wind turbines. Moreover, the reliability of wind turbines becomes more and more important, especially in offshore applications. One potential solution for these demands is the wind turbine drive-train

  8. Transient Simulation Study of Slip-Frequency Vector Control for Variable Speed Doubly-Fed Brushless Motor with Magnetic Barrier Rotor

    Directory of Open Access Journals (Sweden)

    Jingxiong ZHANG

    2014-01-01

    Full Text Available In this paper, a transient simulation model of a variable speed doubly fed brushless motor (DFBM using back-to-back converter is described. Based on analysis of rotor flux oriented vector control theory of doubly fed induction motor, the control of the currents in DFBM that produce the magnetic flux and the torque is achieved by a digital controller, the speed is regulated by a PI controller which is tuned by a genetic algorithm. According to the state equation of DFBM and the control schemes, the system simulation module is established in MATLAB/ SIMULINK. An extensive simulation study is performed to examine the control characteristics of the machine-side converter under different operation conditions in variable-speed DFBM driver system.

  9. Operating Regions of Adjustable-Speed Units with Doubly Fed Machines

    Czech Academy of Sciences Publication Activity Database

    Schreier, Luděk; Chomát, Miroslav; Bendl, Jiří

    2004-01-01

    Roč. 49, č. 2 (2004), s. 119-136 ISSN 0001-7043 R&D Projects: GA AV ČR IAA2057102 Keywords : AC machines * adjustable-speed systems * doubly fed machine Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. Trends in Wind Turbine Generator Systems

    DEFF Research Database (Denmark)

    Polinder, Henk; Ferreira, Jan Abraham; Jensen, Bogi Bech

    2013-01-01

    This paper reviews the trends in wind turbine generator systems. After discussing some important requirements and basic relations, it describes the currently used systems: the constant speed system with squirrel-cage induction generator, and the three variable speed systems with doubly fed...... induction generator (DFIG), with gearbox and fully rated converter, and direct drive (DD). Then, possible future generator systems are reviewed. Hydraulic transmissions are significantly lighter than gearboxes and enable continuously variable transmission, but their efficiency is lower. A brushless DFIG...

  11. Direct torque control design and experimental evaluation for the brushless doubly fed machine

    International Nuclear Information System (INIS)

    Sarasola, Izaskun; Poza, Javier; Rodriguez, Miguel A.; Abad, Gonzalo

    2011-01-01

    In this paper, a direct torque control (DTC) strategy for the brushless doubly fed machine (BDFM) is presented. After analyzing the mathematical model of this machine, the voltage vectors look-up table of classical DTC techniques is derived. Then, the behavior of the machine is studied when it is controlled by the developed DTC technique, concluding that under some specific operation conditions, a BDFM could present a time interval where the torque and the flux can not be controlled simultaneously. In these cases, two different control solutions have been defined: 'flux priority' and 'torque priority'. Finally, simulation and experimental results validate the effectiveness of the proposed control algorithms.

  12. Minimum short-circuit ratios for grid interconnection of wind farms with induction generators

    Energy Technology Data Exchange (ETDEWEB)

    Reginatto, Romeu; Rocha, Carlos [Western Parana State University (UNIOESTE), Foz do Iguacu, PR (Brazil). Center for Engineering and Exact Sciences], Emails: romeu@unioeste.br, croberto@unioeste.br

    2009-07-01

    This paper concerns the problem of determining the minimum value for the short-circuit ratio which is adequate for the interconnection of a given wind farms to a given grid point. First, a set of 3 criteria is defined in order to characterize the quality/safety of the interconnection: acceptable terminal voltage variations, a minimum active power margin, and an acceptable range for the internal voltage angle. Then, the minimum short circuit ratio requirement is determined for 6 different induction generator based wind turbines, both fixed-speed (with and without reactive power compensation) and variable-speed (with the following control policies: reactive power, power factor, and terminal voltage regulation). The minimum short-circuit ratio is determined and shown in graphical results for the 6 wind turbines considered, for X/R in the range 0-15, also analyzing the effect of more/less stringent tolerances for the interconnection criteria. It is observed that the tighter the tolerances the larger the minimum short-circuit ratio required. For the same tolerances in the interconnection criteria, a comparison of the minimum short circuit ratio required for the interconnection of both squirrel-cage and doubly-fed induction generators is presented, showing that the last requires much smaller values for the short-circuit ratio. (author)

  13. Inductive line energy storage generator

    Energy Technology Data Exchange (ETDEWEB)

    Choi, P [Ecole Polytechnique, Palaiseau (France). Laboratoire de Physique des Milieux Ionises

    1997-12-31

    The inductive energy storage (IES) generator has long been considered to be the most efficient system for energy usage in large pulsed power system at the MA level. A number of parameters govern the efficiency of energy transfer between the storage capacitors and the load, and the level of current deliverable to the load. For high power system, the energy storage capacitors are arranged as a Marx generator. The primary constraints are the inductances in the various parts of the circuit, in particular, the upstream inductance between the Marx and the POS, and the downstream inductance between the POS and the load. This paper deals with the effect of replacing part of the upstream inductance with a transmission line and introduces the new concept of an inductive line for energy storage (ILES). Extensive parametric scans were carried out on circuit simulations to investigate the effect of this upstream transmission line. A model was developed to explain the operation of the ILES design based on the data obtained. Comparison with an existing IES generator shows that the ILES design offers a significant improvement in the maximum current and hence energy delivered to an inductive load. (author). 5 figs., 1 ref.

  14. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

    Science.gov (United States)

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.

    2016-08-01

    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  15. A Study of Distributed Generation System Characteristics and Protective Load Control Strategy

    DEFF Research Database (Denmark)

    Wei, Mu; Chen, Zhe

    2011-01-01

    Due to the smaller inertia feature of a Wind Turbine (WT) involved Distributed Generation System (DGS), the WT’s induction generator are more vulnerable to frequency and voltage disturbances. Therefore the study investigates the DGS characteristics respectively from power plants, i.e. WTs and load....... Two kinds of wind turbines: Doubly-fed Induction Generator (DFIG) and Fixed-speed Wind Turbine (FSWT) are compared in this study. A conventional power system protective scheme may not response promptly, which could lead an undesired disconnection of WTs for the turbine protection purpose. Consequently...

  16. Distributed generation induction and permanent magnet generators

    CERN Document Server

    Lai, L

    2007-01-01

    Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generators (IGs) are the cheapest and most commonly used technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples o better demonstrate how the integration of energy sources can be accomplished. The book also provides the ...

  17. Independent Control of Positive- and Negative-Sequence Current Components in a Doubly Fed Machine

    Czech Academy of Sciences Publication Activity Database

    Bendl, Jiří; Chomát, Miroslav; Schreier, Luděk

    2005-01-01

    Roč. 15, č. 3 (2005), s. 191-202 ISSN 1430-144X R&D Projects: GA ČR(CZ) GA102/03/0046 Institutional research plan: CEZ:AV0Z20570509 Keywords : vector control * adjustable speed generation systems * converter control Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.056, year: 2005

  18. Modeling and analysis with induction generators

    CERN Document Server

    Simões, M Godoy

    2014-01-01

    ForewordPrefaceAcknowledgmentsAuthorsPrinciples of Alternative Sources of Energy and Electric GenerationScope of This ChapterLegal DefinitionsPrinciples of Electrical ConversionBasic Definitions of Electrical PowerCharacteristics of Primary SourcesCharacteristics of Remote Industrial, Commercial, and Residential Sites and Rural EnergySelection of the Electric GeneratorInterfacing Primary Source, Generator, and LoadExample of a Simple Integrated Generating and Energy-Storing SystemSolved ProblemsSuggested ProblemsReferencesSteady-State Model of Induction GeneratorsScope of This ChapterInterconnection and Disconnection of the Electric Distribution NetworkRobustness of Induction GeneratorsClassical Steady-State Representation of the Asynchronous MachineGenerated PowerInduced TorqueRepresentation of Induction Generator LossesMeasurement of Induction Generator ParametersBlocked Rotor Test (s = 1)No-Load Test (s = 0)Features of Induction Machines Working as Generators Interconnected to the Distribution NetworkHigh-...

  19. Coordinated control of a DFIG-based wind-power generation system with SGSC under distorted grid voltage conditions

    DEFF Research Database (Denmark)

    Yao, Jun; Li, Qing; Chen, Zhe

    2013-01-01

    in the multiple synchronous rotating reference frames. In order to counteract the adverse effects of the voltage harmonics upon the DFIG, the SGSC generates series compensation control voltages to keep the stator voltage sinusoidal and symmetrical, which allows the use of the conventional vector control strategy......This paper presents a coordinated control method for a doubly-fed induction generator (DFIG)-based wind-power generation system with a series grid-side converter (SGSC) under distorted grid voltage conditions. The detailed mathematical models of the DFIG system with SGSC are developed...

  20. Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

    Institute of Scientific and Technical Information of China (English)

    Xueping PAN; Ping JU; Feng WU; Yuqing JIN

    2017-01-01

    A new hierarchical parameter estimation method for doubly fed induction generator (DFIG) and drive train system in a wind turbine generator (WTG) is proposed in this paper.Firstly,the parameters of the DFIG and the drive train are estimated locally under different types of disturbances.Secondly,a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results.The main benefit of the proposed scheme is the improved estimation accuracy.Estimation results confirm the applicability of the proposed estimation technique.

  1. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Xu, Honghua

    2014-01-01

    This paper presents a fast coordinated control scheme of the rotor side converter (RSC), the DC chopper and the grid side converter (GSC) of doubly fed induction generator (DFIG) wind turbine generators (WTGs) which is to improve the low voltage ride through (LVRT) and high voltage ride through...... were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were...

  2. Improved Control Strategies for a DFIG-Based Wind-Power Generation System with SGSC under Unbalanced and Distorted Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Yao, Jun; Yu, Mengting; Hu, Weihao

    2016-01-01

    This paper investigates an improved control strategy for a doubly-fed induction generator (DFIG) based wind-power generation system with series grid-side converter (SGSC) under network unbalance and harmonic grid voltage distortion conditions. The integrated mathematical modeling of the DFIG system...... with SGSC is established by taking both the negative-sequence and harmonic components of the grid voltages into consideration with multiple synchronous rotating reference frames. Under network unbalance and harmonic distortion situations, stator voltage can be kept symmetrical and sinusoidal by the control...

  3. Design Optimization and Evaluation of Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, Hui

    2008-01-01

    . In this paper, seven variable speed constant frequency (VSCF) wind generator systems are investigated, namely permanent magnet synchronous generators with the direct-driven (PMSG_DD), the single-stage gearbox (PMSG_1G) and three-stage gearbox (PMSG_3G) concepts, doubly fed induction generators with the three......With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind generator systems have been developed and built. The objective of this paper is to evaluate various wind generator systems by optimization designs and comparisons......-stage gearbox (DFIG_3G) and with the single-stage gearbox (DFIG_1G), the electricity excited synchronous generator with the direct-driven (EESG_DD), and the VSCF squirrel cage induction generator with the three-stage gearbox (SCIG_3G). Firstly, the design models of wind turbines, three/single stage gearbox...

  4. Electric Generators and their Control for Large Wind Turbines

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Rallabandi, Vandana

    2017-01-01

    induction generator, the cage rotor induction generator, and the synchronous generator with DC or permanent magnet excitation. The operating principle, performance, optimal design, and the modeling and control of the machine-side converter for each kind of generator are adressed and evaluated. In view......The electric generator and its power electronics interface for wind turbines (WTs) have evolved rapidly toward higher reliability and reduced cost of energy in the last 40 years. This chapter describes the up-to-date electric generators existing in the wind power industry, namely, the doubly fed...... of the fact that individual power rating of WTs has increased to around 10 MW, generator design and control technologies required to reach this power rating are discussed....

  5. 1 MV low-induction pulse generator

    International Nuclear Information System (INIS)

    Koba, G.I.; Koba, Yu.V.; Slivkov, I.N.; Sukhov, A.D.; Tarumov, Eh.Z.

    1980-01-01

    A high-voltage pulse generator is described. The generator Uses the Arkadiev-Marx circuit at 1 MV voltage and 12 kJ energy; the inductance of the discharge circuit is 1.3 μN. Low inductance of the generator has been obtained due to the use of low-inductance capacitors and employment of bifilar buses with oil barrier insulation. To provide reliable generator triggering, an ignition circuit has been developed with a resistive coupling between generator steps, based on controlled three-electrode sparkgaps with a distorted field. The generator switching time is slightly dependent on pressure and constitutes 200-300 ns. The generator efficiency is 83%

  6. Induction generator models in dynamic simulation tools

    DEFF Research Database (Denmark)

    Knudsen, Hans; Akhmatov, Vladislav

    1999-01-01

    For AC network with large amount of induction generators (windmills) the paper demonstrates a significant discrepancy in the simulated voltage recovery after fault in weak networks when comparing dynamic and transient stability descriptions and the reasons of discrepancies are explained...

  7. Induction generator-induction motor wind-powered pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, M.S.; Lyra, R.O.C.; Silva, S.R. [CPDEE - UFMG, Belo Horizonte (Brazil)

    1997-12-31

    The energy storage matter plays an important role in wind-electric conversion systems for isolated applications. Having that in mind, two different approaches can be basically considered: either the immediate conversion of the generated electric energy, as in a water pumping system or electric energy storage for later use, as in a battery charging system. Due to some features such as no need of an external reactive power source and, sometimes, a gearbox, permanent-magnet synchronous generators have been broadly used in low rated power isolated systems. Despite that, system performance can be affected when the generator is feeding an inductive load (e.g., an induction motor) under variable-speed-variable-frequency operational conditions. Since there is no effective flux control, motor overload may occur at high wind speeds. Thus, good system performance can be obtained through additional control devices which may increase system cost. Although being rugged and cheap, induction machines always work as a reactive power drain; therefore, they demand an external reactive power source. Considering that, reactive static compensators appear as an attractive alternative to the cost x performance problem. In addition to that, different control strategies can be used so that system performance can be improved.

  8. High Power Wind Generator Designs with Less or No PMs

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Blaabjerg, Frede

    2014-01-01

    synchronous generators, by doubly-fed (wound rotor) induction and cage induction generators and by introducing new topologies with pertinent costs for high power (MW range) wind energy conversion units. The present overview attempts, based on recent grid specifications, an evaluation of commercial and novel...... considering the interaction with the PWM converter in terms of power/speed range, losses, kVA, and costs) rather than on the control issues which abound in literature, will be of use for future R&D efforts in wind energy conversion, storage and use.......The recent steep increase in high energy permanent magnet (PM) price (above 130$/kg and more) triggered already strong R&D efforts to develop wind generators with less PMs (less weight in NdFeB magnets/kW or the use of ferrite PMs) or fully without PMs. All these by optimizing existing dc excited...

  9. A comparative investigation of three PM-less MW power range wind generator topologies

    DEFF Research Database (Denmark)

    Bratiloveanu, Catalin-Rauti; Traian Cosmin Anghelus, Dumitru; Boldea, I.

    2012-01-01

    As the wind energy penetration range increases steadily and the high energy PM costs are rising dramatically, PM-less large power wind generators with high performance are needed. Apart from extending the range of cage rotor induction generators, doubly-fed induction generators and dc excited...... investigates by quasi 2D-FEM two dc stator polarized (to increase machine side PWM converter voltage utilization, that is to reduce peak kVA ratings and costs of the machine side PWM converter) directly-driven switched reluctance generators (one with circumferential field and one with transverse flux (with...... heteropolar-rotor (standard) synchronous generators, especially for direct drives (very low speed) and multibrid (with single stage transmission (5/1-8/1 ratio)), new topologies have to be investigated to reduce initial costs and weights for high enough efficiency and energy annual yield. The present paper...

  10. Generator dynamics in aeroelastic analysis and simulations

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Hansen, Morten Hartvig; Iov, F.

    2003-01-01

    This report contains a description of a dynamic model for a doubly-fed induction generator. The model has physical input parameters (voltage, resistance, reactance etc.) and can be used to calculate rotor and stator currents, hence active and reactivepower. A perturbation method has been used...... to reduce the original generator model equations to a set of equations which can be solved with the same time steps as a typical aeroelastic code. The method is used to separate the fast transients of the modelfrom the slow variations and deduce a reduced order expression for the slow part. Dynamic effects...... of the first order terms in the model as well as the influence on drive train eigenfrequencies and damping has been investigated. Load response during timesimulation of wind turbine response have been compared to simulations with a traditional static generator model based entirely on the slip angle. A 2 MW...

  11. Phase 3 of a Brushless Doubly-Fed Machine System Development Program : Final Technical Report for Period January 1, 1992-June 30, 1993.

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Gerald C.; Spee, Rene; Wallace, Alan K.

    1993-12-31

    Since the inception of the BDFM development program in 1989, the value of BDFM technology has become apparent. The BDFM provides for adjustable speed, synchronous operation while keeping costs associated with the required power conversion equipment lower than in competing technologies. This provides for an advantage in initial as well as maintenance expenses over conventional drive system. Thus, the BDFM enables energy efficient, adjustable speed process control for applications where established drive technology has not been able to deliver satisfactory returns on investment. At the same time, the BDFM challenges conventional drive technologies in established markets by providing for improved performance at lower cost. BDFM converter rating is kept at a minimum, which significantly improves power quality at the utility interface over competing power conversion equipment. In summary, BDFM technology can be expected to provide significant benefits to utilities as well as their customers. This report discusses technical research and development activities related to Phase 3 of the Brushless Doubly-Fed Machine System Development Program, including work made possible by supplemental funds for laboratory improvement and prototype construction. Market research for the BDFM was provided by the College of Business at Oregon State University; market study results will be discussed in a separate report.

  12. Adaptive Backstepping Control Based on Floating Offshore High Temperature Superconductor Generator for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Feng Yang

    2014-01-01

    Full Text Available With the rapid development of offshore wind power, the doubly fed induction generator and permanent magnet synchronous generator cannot meet the increasing request of power capacity. Therefore, superconducting generator should be used instead of the traditional motor, which can improve generator efficiency, reduce the weight of wind turbines, and increase system reliability. This paper mainly focuses on nonlinear control in the offshore wind power system which is consisted of a wind turbine and a high temperature superconductor generator. The proposed control approach is based on the adaptive backstepping method. Its main purpose is to regulate the rotor speed and generator voltage, therefore, achieving the maximum power point tracking (MPPT, improving the efficiency of a wind turbine, and then enhancing the system’s stability and robustness under large disturbances. The control approach can ensure high precision of generator speed tracking, which is confirmed in both the theoretical analysis and numerical simulation.

  13. Operating of Small Wind Power Plants with Induction Generators

    OpenAIRE

    Jakub Nevrala; Stanislav Misak

    2008-01-01

    This paper describes different systems of small wind power plants with induction generators used in the Czech Republic. Problems of wind power plants running with induction generators are solved within partial target of the research project MSM 6198910007. For small wind power plants is used induction motor as a generator. Parameters of the name plate of motor must be resolved for generator running on measuring base. These generators are running as a separately working generators or generator...

  14. Development of a Cost Effective Power Generation System: An Overview

    Directory of Open Access Journals (Sweden)

    Shiv Prakash Bihari

    2016-03-01

    Full Text Available This paper presents an overview on development of cost effective power generation system and motivates for development of a model for hybrid system with wind to investigate the combined operation of wind with different sources to cater to wind’s stochastic nature for imbalance minimization and optimal operation. Development of model for trading power in competitive electricity market and development of strategies for trading in electricity markets (wind energy and reserves markets to investigate the effects of real time pricing tariffs on electricity market operation has been illustrated in this paper. Dynamic modelling related studies to investigate the wind generator’s kinetic energy for primary frequency support using simulink and simulation studies on doubly fed induction generator to study its capability during small disturbances / fluctuations on power system have been described.

  15. Stability improvement of induction generator-based wind turbine systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Hu, Y.; Blaabjerg, Frede

    2007-01-01

    The stability improvement of induction-generator-based wind turbine systems under power system fault conditions has been studied. Two types of generators are considered, namely rotor short-circuited induction generators and dynamic slip-controlled wound rotor induction generators. The factors...... affecting the stability are analysed. The characteristics of the induction-generator-based wind turbines are described, and possible methods of improving stability of the wind generators are discussed. The system modelling is presented, and then the discussed methods of improving stability are investigated...

  16. Stand-alone induction generators for small water power schemes

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Adam [Intermediate Technology Development Group, Rugby (United Kingdom); Smith, Nigel [Smith Associates, Nottingham (United Kingdom)

    1996-04-01

    Conventional technology for isolated power generation is the synchronous generator. Using stand-alone induction generators has proved to have tremendous advantages in remote regions of developing countries, where electricity has significant social benefits. (author)

  17. Analysis of generator bearing vibration data for diagnosing rotor circuit malfunction in DFIGs

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Sweeney, Christian W.; Jensen, Bogi Bech

    2014-01-01

    Doubly fed induction generators (DFIGs) are the most popular configuration met in the wind energy sector occu- pying approximately 65 % of the total market share. Condition monitoring of wind turbine generators is performed based on vibration data collected from accelerometers mounted on the drive....... In this paper generator bearing vibration signature for a DFIG under operation with one rotor phase coil open is analysed and presented. Further this failure mode is compared to rotor dynamics fault, such as rotational looseness, and the difference in signature is discussed. Vibration data from a multi...... end and non-drive end bearings, meeting the requirements of numerous turbine operators for condition based maintenance. In a DFIG the voltage applied to the rotor is controlled by a converter, where electric connection between the two is accom- plished by using slip rings. Improper connection between...

  18. Pulsed power generators using an inductive energy storage system

    International Nuclear Information System (INIS)

    Akiyama, H.; Sueda, T.; Katschinski, U.; Katsuki, S.; Maeda, S.

    1996-01-01

    The pulsed power generators using an inductive energy storage system are extremely compact and lightweight in comparison with those using a capacitive energy storage system. The reliable and repetitively operated opening switch is necessary to realize the inductive pulsed power generator. Here, the pulsed power generators using the inductive energy storage system, which have been developed in Kumamoto University, are summarized. copyright 1996 American Institute of Physics

  19. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2014-06-01

    Full Text Available This paper presents a fast coordinated control scheme of the rotor side converter (RSC, the Direct Current (DC chopper and the grid side converter (GSC of doubly fed induction generator (DFIG wind turbine generators (WTGs to improve the low voltage ride through (LVRT and high voltage ride through (HVRT capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient periods of grid voltage changes. The protection schemes of the rotor crowbar circuit and the DC chopper circuit were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were verified by time domain simulations using Matlab-Simulink.

  20. Dynamics of 'abc' and 'qd' constant parameters induction generator model

    DEFF Research Database (Denmark)

    Fajardo-R, L.A.; Medina, A.; Iov, F.

    2009-01-01

    In this paper, parametric sensibility effects on dynamics of the induction generator in the presence of local perturbations are investigated. The study is conducted in a 3x2 MW wind park dealing with abc, qd0 and qd reduced order, induction generator model respectively, and with fluxes as state...

  1. Power generation using photovoltaic induction in an isolated power network

    International Nuclear Information System (INIS)

    Kalantar, M.; Jiang, J.

    2001-01-01

    Owing to increased emphasis on renewable resources, the development of suitable isolated power generators driven by energy sources, the development of suitable isolated power generators driven by energy sources such as photovoltaic, wind, small hydroelectric, biogas and etc. has recently assumed greater significance. A single phase capacitor self excited induction generator has emerged as a suitable candidate of isolated power sources. This paper presents performance analysis of a single phase self-excited induction generator driven by photovoltaic (P V) system for low power isolated stand-alone applications. A single phase induction machine can work as a self-excited induction generator when its rotor is driven at suitable speed by an photovoltaic powered do motor. Its excitation is provided by connecting a single phase capacitor bank at a stator terminals. Either to augment grid power or to get uninterrupted power during grid failure stand-alone low capacity ac generators are used. These are driven by photovoltaic, wind power or I C engines using kerosene, diesel, petrol or biogas as fuel. Self-excitation with capacitors at the stator terminals of the stator terminals of the induction machines is well demonstrated experimentally on a P V powered dc motor-induction machine set. The parameters and the excitation requirements of the induction machine run in self-excited induction generator mode are determined. The effects of variations in prime mover speed,terminal capacitance and load power factor on the machine terminal voltage are studied

  2. Cutting-in control of the variable speed constant frequency wind power generator based on internal model controller

    Energy Technology Data Exchange (ETDEWEB)

    Guo Jindong; Xu Honghua; Zhao Dongli [Inst. of Electrical Engineering, CAS, BJ (China)

    2008-07-01

    The no-impact-current cutting-in-network control is the key of variable speed constant frequency (VSCF) wind power control system. Based on the stator flux linkage oriented control theory of doubly fed induction generator (DFIG), the field-oriented vector control technique and the internal model controller (IMC) are transplanted into the voltage control of DFIG and a novel cutting-in control strategy is obtained. The strategy does not need the exact inductor generator model, and has perfect performance without overshoot. The structure of the controller is simple, and the only parameter to be adjusted is directly related to system performance, so the strategy is easy to realize. Finally the strategy is studied by simulation using Matlab, the results of the simulation show that the control strategy can effectively control the stator voltage. (orig.)

  3. A Novel Passive Islanding Detection Scheme for Distributed Generations Based on Rate of Change of Positive Sequence Component of Voltage and Current

    DEFF Research Database (Denmark)

    Rostami, Ali; Jalilian, Amin; Naderi, Seyed Behzad

    2017-01-01

    ) based wind turbine and synchronous diesel generator DGs by MATLAB/Simulink software. Different non-islanding case studies are taken into account to evaluate the effectiveness of the proposed approach. The simulation results show that the proposed method has advantage of detecting the islanding rapidly......Islanding operation is one of serious hazards of distributed generation (DG) applications. According to IEEE 1547 standard, its occurrence must be detected within two seconds. This paper presents a novel passive islanding detection method based on rate of change of positive sequence component...... of RCPSC and RCPSV exceed the predetermined threshold values, it is concluded that the islanding condition has occurred. Otherwise, it is considered as a non-islanding event. The performance of the proposed method is investigated on a sample network in the presence of doubly fed induction generator (DFIG...

  4. Research on grid connection control technology of double fed wind generator

    Science.gov (United States)

    Ling, Li

    2017-01-01

    The composition and working principle of variable speed constant frequency doubly fed wind power generation system is discussed in this thesis. On the basis of theoretical analysis and control on the modeling, the doubly fed wind power generation simulation control system is designed based on a TMS320F2407 digital signal processor (DSP), and has done a large amount of experimental research, which mainly include, variable speed constant frequency, constant pressure, Grid connected control experiment. The running results show that the design of simulation control system is reasonable and can meet the need of experimental research.

  5. Operating of Small Wind Power Plants with Induction Generators

    Directory of Open Access Journals (Sweden)

    Jakub Nevrala

    2008-01-01

    Full Text Available This paper describes different systems of small wind power plants with induction generators used in the Czech Republic. Problems of wind power plants running with induction generators are solved within partial target of the research project MSM 6198910007. For small wind power plants is used induction motor as a generator. Parameters of the name plate of motor must be resolved for generator running on measuring base. These generators are running as a separately working generators or generators connected to the power grid. Methods of control these systems as a separately working, directly connecting to power grid, control by frequency converter and wiring by synchronous cascade are confronted on the measuring base too.

  6. Optimized Generator Designs for the DTU 10-MW Offshore Wind Turbine using GeneratorSE

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha; Maness, Michael; Dykes, Katherine

    2017-01-09

    Compared to land-based applications, offshore wind imposes challenges for the development of next generation wind turbine generator technology. Direct-drive generators are believed to offer high availability, efficiency, and reduced operation and maintenance requirements; however, previous research suggests difficulties in scaling to several megawatts or more in size. The resulting designs are excessively large and/or massive, which are major impediments to transportation logistics, especially for offshore applications. At the same time, geared wind turbines continue to sustain offshore market growth through relatively cheaper and lightweight generators. However, reliability issues associated with mechanical components in a geared system create significant operation and maintenance costs, and these costs make up a large portion of overall system costs offshore. Thus, direct-drive turbines are likely to outnumber their gear-driven counterparts for this market, and there is a need to review the costs or opportunities of building machines with different types of generators and examining their competitiveness at the sizes necessary for the next generation of offshore wind turbines. In this paper, we use GeneratorSE, the National Renewable Energy Laboratory's newly developed systems engineering generator sizing tool to estimate mass, efficiency, and the costs of different generator technologies satisfying the electromagnetic, structural, and basic thermal design requirements for application in a very large-scale offshore wind turbine such as the Technical University of Denmark's (DTU) 10-MW reference wind turbine. For the DTU reference wind turbine, we use the previously mentioned criteria to optimize a direct-drive, radial flux, permanent-magnet synchronous generator; a direct-drive electrically excited synchronous generator; a medium-speed permanent-magnet generator; and a high-speed, doubly-fed induction generator. Preliminary analysis of leveled costs of

  7. Optimized Generator Designs for the DTU 10-MW Offshore Wind Turbine using GeneratorSE: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha; Maness, Michael; Dykes, Katherine

    2017-01-01

    Compared to land-based applications, offshore wind imposes challenges for the development of next generation wind turbine generator technology. Direct-drive generators are believed to offer high availability, efficiency, and reduced operation and maintenance requirements; however, previous research suggests difficulties in scaling to several megawatts or more in size. The resulting designs are excessively large and/or massive, which are major impediments to transportation logistics, especially for offshore applications. At the same time, geared wind turbines continue to sustain offshore market growth through relatively cheaper and lightweight generators. However, reliability issues associated with mechanical components in a geared system create significant operation and maintenance costs, and these costs make up a large portion of overall system costs offshore. Thus, direct-drive turbines are likely to outnumber their gear-driven counterparts for this market, and there is a need to review the costs or opportunities of building machines with different types of generators and examining their competitiveness at the sizes necessary for the next generation of offshore wind turbines. In this paper, we use GeneratorSE, the National Renewable Energy Laboratory's newly developed systems engineering generator sizing tool to estimate mass, efficiency, and the costs of different generator technologies satisfying the electromagnetic, structural, and basic thermal design requirements for application in a very large-scale offshore wind turbine such as the Technical University of Denmark's (DTU) 10-MW reference wind turbine. For the DTU reference wind turbine, we use the previously mentioned criteria to optimize a direct-drive, radial flux, permanent-magnet synchronous generator; a direct-drive electrically excited synchronous generator; a medium-speed permanent-magnet generator; and a high-speed, doubly-fed induction generator. Preliminary analysis of leveled costs of

  8. Non-inductive electric current generation with the Alfven waves

    International Nuclear Information System (INIS)

    Assis, A.S. de.

    1988-01-01

    Non-inductive current generation by means of radio frequency waves is studied using one-dimensional (1D) quasilinear equations. The main results obtained in this thesis are the general expressions for the current generated, for the efficiency of current generation and for the critical power - the lowest power required for current saturation. (M.W.O.) [pt

  9. Dynamic models for distributed generation resources

    Energy Technology Data Exchange (ETDEWEB)

    Morched, A.S. [BPR Energie, Sherbrooke, PQ (Canada)

    2010-07-01

    Distributed resources can impact the performance of host power systems during both normal and abnormal system conditions. This PowerPoint presentation discussed the use of dynamic models for identifying potential interaction problems between interconnected systems. The models were designed to simulate steady state behaviour as well as transient responses to system disturbances. The distributed generators included directly coupled and electronically coupled generators. The directly coupled generator was driven by wind turbines. Simplified models of grid-side inverters, electronically coupled wind generators and doubly-fed induction generators (DFIGs) were presented. The responses of DFIGs to wind variations were evaluated. Synchronous machine and electronically coupled generator responses were compared. The system model components included load models, generators, protection systems, and system equivalents. Frequency responses to islanding events were reviewed. The study demonstrated that accurate simulations are needed to predict the impact of distributed generation resources on the performance of host systems. Advances in distributed generation technology have outpaced the development of models needed for integration studies. tabs., figs.

  10. Generator dynamics in aeroelastic analysis and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, T.J.; Hansen, M.H.; Iov, F.

    2003-05-01

    This report contains a description of a dynamic model for a doubly-fed induction generator implemented in the aeroelastic code HAWC. The model has physical input parameters (resistance, reactance etc.) and input variables (stator and rotor voltage and rotor speed). The model can be used to simulate the generator torque as well as the rotor and stator currents, active and reactive power. A perturbation method has been used to reduce the original generator model equations to a set of equations which can be solved with the same time steps as a typical aeroelastic code. The method is used to separate the fast transients of the model from the slow variations and deduce a reduced order expression for the slow part. Dynamic effects of the first order terms in the model as well as the influence on drive train eigenfrequencies and damping has been investigated. Load response during time simulation of wind turbine response have been compared to simulations with a linear static generator model originally implemented i HAWC. A 2 MW turbine has been modelled in the aeroelastic code HAWC. When using the new dynamic generator model there is an interesting coupling between the generator dynamics and a global turbine vibration mode at 4.5 Hz, which only occurs when a dynamic formulation of the generator equations is applied. This frequency can especially be seen in the electrical power of the generator and the rotational speed of the generator, but also as torque variations in the drive train. (au)

  11. Induction Generators for Direct-Drive Wind Turbines

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech

    2011-01-01

    This paper considers the use of a squirrel cage induction generator for a direct-drive wind turbine. Advantages of this topology include a simple/rugged construction, and no need for permanent magnets. A major focus of this paper is the choice of an appropriate pole number. An iterative, analytical...

  12. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    International Nuclear Information System (INIS)

    Ahmed, D; Ahmad, A

    2013-01-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  13. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    Science.gov (United States)

    Ahmed, D.; Ahmad, A.

    2013-06-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  14. Modelling of windmill induction generators in dynamic simulation programs

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Knudsen, Hans

    1999-01-01

    with and without a model of the mechanical shaft. The reason for the discrepancies are explained, and it is shown that the phenomenon is due partly to the presence of DC offset currents in the induction machine stator, and partly to the mechanical shaft system of the wind turbine and the generator rotor......For AC networks with large amounts of induction generators-in case of e.g. windmills-the paper demonstrates a significant discrepancy in the simulated voltage recovery after faults in weak networks, when comparing result obtained with dynamic stability programs and transient programs, respectively....... It is shown that it is possible to include a transient model in dynamic stability programs and thus obtain correct results also in dynamic stability programs. A mechanical model of the shaft system has also been included in the generator model...

  15. Inductive energy store (IES) technology for multi-terrawatt generators

    International Nuclear Information System (INIS)

    Sincerny, P.S.; Ashby, S.R.; Childers, F.K.; Deeney, C.; Kortbawi, D.; Goyer, J.R.; Riordan, J.C.; Roth, I.S.; Stallings, C.; Schlitt, L.

    1993-01-01

    An IES pulsed power machine has been built at Physics International Company that serves as a prototype demonstration of IES technology that is scaleable to very large TW generators. The prototype module utilizes inductive store opening switch technology for the final stage of pulse compression and is capable of driving both electron beam Bremsstrahlung loads or imploding plasma loads. Each module consists of a fast discharge Marx driving a water dielectric transfer capacitor which is command triggered to drive the inductive store section of the machine. The inductive store is discharged into the load using a plasma erosion opening switch. Data demonstrating 22% efficient operation into an electron beam diode load are presented. The system issues addressing the combining of these modules into a very large pulsed power machine are discussed

  16. Study of non inductive current generation in a plasma

    International Nuclear Information System (INIS)

    Rax, J.M.

    1987-01-01

    The problem of non-thermal bremsstrahlung during lower hybrid current drive is considered. The proposed method shows the role of the Compton effects at low frequencies and allows us to establish the link between the emitted power and the absorbed power at high frequency. The non-thermal emission is considered as a kinematical mode conversion between the absorbed radio-frequency mode and the emitted X ray photons. The fast electrons diagnostics and the ways to reach the wave structure are shown. Kinetic and electromagnetic problems concerning current generation are described. The plasma properties and diagnostics in the case of a non inductive current generation are discussed [fr

  17. A neural model of rule generation in inductive reasoning.

    Science.gov (United States)

    Rasmussen, Daniel; Eliasmith, Chris

    2011-01-01

    Inductive reasoning is a fundamental and complex aspect of human intelligence. In particular, how do subjects, given a set of particular examples, generate general descriptions of the rules governing that set? We present a biologically plausible method for accomplishing this task and implement it in a spiking neuron model. We demonstrate the success of this model by applying it to the problem domain of Raven's Progressive Matrices, a widely used tool in the field of intelligence testing. The model is able to generate the rules necessary to correctly solve Raven's items, as well as recreate many of the experimental effects observed in human subjects. Copyright © 2011 Cognitive Science Society, Inc.

  18. Investigation of torque control using a variable slip induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Bossanyi, E A; Gamble, C R

    1991-07-01

    An investigation of the possibilities of using a variable slip induction generator to control wind turbine transmission torque has been carried out. Such a generator consists of a wound rotor induction generator with its rotor winding connected to an external variable resistance circuit. By controlling the external resistance, the torque-slip characteristic of the generator can be modified, allowing efficient, low-slip operation below rated wind speed and compliant, high-slip operation above rated, where the additional losses are of no consequence but the resulting compliance allows a much reduced duty to be specified for the transmission and gearbox. A number of hardware options have been investigated for the variable resistance rotor circuit, the main options being either a rectifier and DC chopper or an AC regulator. Both of these options use semiconductor switching devices, for which the relative merits of thyristors, MOSFETs, GTOs and transistors have been investigated. A favoured scheme consisting of an AC regulator using GTOs has been provisionally selected. This choice uses some non-standard equipment but is expected to give negligible problems with harmonics. A comprehensive simulation model has been set up and used to investigate the behaviour of the whole system. (author).

  19. INTERRAD - inductive terawatt X-ray generator (project)

    Energy Technology Data Exchange (ETDEWEB)

    Popkov, N F; Pikar` , A S; Kargin, V I; Ryaslov, E A; Lyubomirskij, A G [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    The results are given of the development and experimental research of explosive electron beam accelerator circuits powered by magneto-cumulative generators forming the current pulse, using explosive plasma opening switches. The conceptual lay-out of inductive terawatt X-ray generators powered by EMGs is proposed. The calculation results of the terawatt x-ray generator including the load placed in a special bunker are presented. Analyzed are the losses at the stage of the HE energy conversion into that of the magnetic fields, those occur ing in transmission along the high-voltage cable line, as well as the processes developing in the plasma opening switches. (author). 2 figs., 6 refs.

  20. Identification of voltage collapse point in self excited induction generator

    Directory of Open Access Journals (Sweden)

    Kalyanasundaram Rajambal

    2009-10-01

    Full Text Available This paper presents a direct equilibrium tracing method for identifying the voltage collapse point of a self-excitedinduction generator (SEIG without many trials. The technique solves differential and algebraic equations simultaneously toobtain the variables in a single step. The load parameter is also automatically varied during equilibrium tracing and thisreduces the computational time significantly. Comparing the simulation results obtained through conventional iterative procedure shows the effectiveness of the technique. An experimental verification on a 1.5KW induction machine validates the simulation results.

  1. Variable speed wind turbine generator system with current controlled voltage source inverter

    International Nuclear Information System (INIS)

    Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

    2011-01-01

    highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  2. Variable speed wind turbine generator system with current controlled voltage source inverter

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

    2011-07-15

    highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  3. Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Hsu, P.; Muljadi, E.; Gao, W.

    2015-04-06

    Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate this impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.

  4. Transient performances analysis of wind turbine system with induction generator including flux saturation and skin effect

    DEFF Research Database (Denmark)

    Li, H.; Zhao, B.; Han, L.

    2010-01-01

    In order to analyze correctly the effect of different models for induction generators on the transient performances of large wind power generation, Wind turbine driven squirrel cage induction generator (SCIG) models taking into account both main and leakage flux saturation and skin effect were...

  5. Harmonics reduction in standalone DFIG-DC system by shunt active ...

    Indian Academy of Sciences (India)

    Himanshu Misra

    2018-05-22

    May 22, 2018 ... Doubly fed induction generator; standalone; DC voltage regulation; shunt active filter; harmonics ... Operation and design issue of DFIG in DC-net interface is ...... control systems for the operation of DFIGs in wind energy.

  6. Inductive thermal plasma generation applied for the materials coating

    International Nuclear Information System (INIS)

    Pacheco, J.; Pena, R.; Cota, G.; Segovia, A.; Cruz, A.

    1996-01-01

    The coatings by thermal plasma are carried out introducing particles into a plasma system where they are accelerated and melted (total or partially) before striking the substrate to which they adhere and are suddenly cooled down. The nature of consolidation and solidification of the particles allows to have control upon the microstructure of the deposit. This technique is able to deposit any kind of material that is suitable to be merged (metal, alloy, ceramic, glass) upon any type of substrate (metal, graphite, ceramic, wood) with an adjustable thickness ranging from a few microns up to several millimeters. The applications are particularly focused to the coating of materials in order to improve their properties of resistance to corrosion, thermal and mechanical efforts as well as to preserve the properties of the so formed compound. In this work the electromagnetic induction phenomenon in an ionized medium by means of electric conductivity, is described. Emphasis is made on the devices and control systems employed in order to generate the thermal plasma and in carrying out the coatings of surfaces by the projection of particles based on plasma

  7. Transient Model Validation of Fixed-Speed Induction Generator Using Wind Farm Measurements

    DEFF Research Database (Denmark)

    Rogdakis, Georgios; Garcia-Valle, Rodrigo; Arana Aristi, Iván

    2012-01-01

    In this paper, an electromagnetic transient model for fixed-speed wind turbines equipped with induction generators is developed and implemented in PSCAD/EMTDC. The model is comprised by: an induction generator, aerodynamic rotor, and a two-mass representation of the shaft system. Model validation...

  8. Size Reduction Techniques for Large Scale Permanent Magnet Generators in Wind Turbines

    Science.gov (United States)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    2015-03-01

    Increased wind penetration is necessary to reduce U.S. dependence on fossil fuels, combat climate change and increase national energy security. The U.S Department of Energy has recommended large scale and offshore wind turbines to achieve 20% wind electricity generation by 2030. Currently, geared doubly-fed induction generators (DFIGs) are typically employed in the drivetrain for conversion of mechanical to electrical energy. Yet, gearboxes account for the greatest downtime of wind turbines, decreasing reliability and contributing to loss of profit. Direct drive permanent magnet generators (PMGs) offer a reliable alternative to DFIGs by eliminating the gearbox. However, PMGs scale up in size and weight much more rapidly than DFIGs as rated power is increased, presenting significant challenges for large scale wind turbine application. Thus, size reduction techniques are needed for viability of PMGs in large scale wind turbines. Two size reduction techniques are presented. It is demonstrated that 25% size reduction of a 10MW PMG is possible with a high remanence theoretical permanent magnet. Additionally, the use of a Halbach cylinder in an outer rotor PMG is investigated to focus magnetic flux over the rotor surface in order to increase torque. This work was supported by the National Science Foundation under Grant No. 1069283 and a Barbara and James Palmer Endowment at Iowa State University.

  9. Energy Storage Opportunities and Capabilities in a Type 3 Wind Turbine Generator: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Gevorgian, Vahan; Hoke, Andy

    2016-09-01

    Wind power plants and other renewable power plants with power electronic interfaces are capable of delivering frequency response (both governor and/or inertial response) to the grid by a control action; thus, the reduction of available online inertia as conventional power plants are retired can be compensated by designing renewable power plant controls to include frequency response. The source of energy to be delivered as inertial response is determined by the type of generation and control strategy chosen. The cost of energy storage is expected to drop over time, and global research activities on energy storage are very active, funded both by the private industry and governments. Different industry sectors (e.g., transportation, energy) are the major drivers of the recent storage research and development. This work investigates the opportunities and capabilities of deploying energy storage in renewable power plants. In particular, we focus on wind power plants with doubly-fed induction generators, or Type 3 wind turbine generator (WTGs). We find that the total output power of a system with Type 3 WTGs with energy storage can deliver a power boost during inertial response that is up to 45% higher than one without energy storage without affecting the torque limit, thus enabling an effective delivery of ancillary services to the grid.

  10. Transformer supply of inductive and resistive loads of a magnetocumulative generator

    International Nuclear Information System (INIS)

    Kravchenko, A.S.; Lyudaev, R.Z.; Pavlovskij, A.I.; Plyashkevich, L.N.; Shuvalov, A.M.

    1981-01-01

    Variants of transformer energy outlet from magnetocumulative generator (MCG) to inductive and resistive loads are considered. For engineer calculations of transformer MCG electrotechnical model supplemented with a known from the experiment fact of existence of optimum by energy generator finite inductivity turns to be useful. The possibility of current front shortening in the load using a transformer idle running and current pulse shaping at current damping upon the finishing of generator performance is considered [ru

  11. Analysis of the Dynamic Performance of Self-Excited Induction Generators Employed in Renewable Energy Generation

    Directory of Open Access Journals (Sweden)

    Mohamed E. A. Farrag

    2014-01-01

    Full Text Available Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG in the distribution network. Self-Excited Induction Generators (SEIG represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG and the active load (essential for balancing power generation and demand. This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.

  12. Theoretical and experimental analysis of the induction generators; Analise teorica e experimental do gerador de inducao

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Marcel; Martins Neto, Luciano; Calixto, Wesley Pacheco; Gontijo, Andre Luiz; Alves, Aylton Jose [Universidade Federal de Uberlandia (LMEE/FEELT/UFU), MG (Brazil). Fac. de Engenharia Eletrica. Lab. de Maquinas Eletricas Especiais], E-mails: marcel@mestrado.ufu.br, lmn@ufu.br, wpcalixto@ieee.org, aja@cefetgo.br

    2009-10-15

    Due to its lower costs, robustness, reduced maintenance and easy operation, the induction generator shows to be an economic alternative in small power generator systems. This work presents the initial phase of pertinent studies about the employment of the induction generator directly connected to the electrical power grid in a pilot project to be implemented at the Santa Luzia SHP. A project that aims to raise relevant operational aspects and to evidence some advantages about the employment of the induction generator in small power generator systems. This phase comprises the experimentation of an induction generator directly connected to the power grid in a laboratorial scale, plus a computational modeling which represents the same. This computational modeling takes into account loads variations which are being supplied by the generator, unbalance between phases and magnetic saturation effects, such as harmonic distortions in the generated currents. From the experimental model collected data, a theoretical-experimental confrontation of the computational modeling is made, where quantitative and qualitative analyses about the operational characteristics of the machine are made. The results of this work will head the operation and supervision of the SHP induction machine. (author)

  13. Two methods for damping torsional vibrations in DFIG-based wind generators using power converters

    Science.gov (United States)

    Zhao, Zuyi; Lu, Yupu; Xie, Da; Yu, Songtao; Wu, Wangping

    2017-01-01

    This paper proposes novel damping control algorithms by using static synchronous compensator (STATCOM) and energy storage system (ESS) to damp torsional vibrations in doubly fed induction generator (DFIG) based wind turbine systems. It first analyses the operating characteristics of STATCOM and ESS for regulating power variations to increase grid voltage stability. Then, new control strategies for STATCOM and ESS are introduced to damp the vibrations. It is followed by illustration of their effectiveness to damp the drive train torsional vibrations of wind turbines, which can be caused by grid disturbances, such as voltage sags and frequency fluctuations. Results suggest that STATCOM is a promising technology to mitigate the torsional vibrations caused by grid voltage sags. By contrast, the ESS connected to the point of common coupling (PCC) of wind turbine systems shows even obvious advantages because of its capability of absorbing/releasing both active and reactive power. It can thus be concluded that STATCOM is useful for stabilizing power system voltage fluctuations, and ESS is more effective both in regulating PCC voltage fluctuations and damping torsional vibrations caused by grid voltage frequency fluctuations.

  14. Current pulse generator of an induction accelerator electromagnet

    International Nuclear Information System (INIS)

    Baginskij, B.A.; Makarevich, V.N.; Shtejn, M.M.

    1987-01-01

    Thyristor generator forming in betatron electromagnet coil sinusoidal and quasisinusoidal current unipolar pulses, the field being deforced at the beginning of acceleration cycle, and with the pulse flat top in the cycle end, is described. The current amplitude is controlled by pulse-phase method. The current pulse time shift permitted to decrease the loss rate in the accumulating capacitor. The generator is used in systems with 1-10 ms pulse duration, electromagnet magnetic field maximal energy - 45-450 J, the voltage amplitude in the coil 960-1500 V and amplitude of the current passing the coil 100-500 A, the repetition frequency being 50-200 Hz. In particular, the generator is used to supply betatrons designed for defectoscopy in nonstationary conditions, the accelerated electron energy being 4, 6, 8 and 15 MeV

  15. Low-induction pulse current generator with a volume bus arrangement

    International Nuclear Information System (INIS)

    Bocharov, Yu.N.; Krivosheev, S.I.; Lapin, N.G.; Shneerson, G.A.

    1993-01-01

    Pulse current generator (PC6) with 38 kj stored energy designed for up to 50 kV charging voltage used to obtain magnetic fields within megagauss range, is described. Space (volume) bus arrangement of its modules is used to reduce eigen inductance of PC6. Current is commutated by solid-body spark gaps. Under 3uH inductive load PC6 provides for formation of up to 2.25 MA current pulse with 3.3x10 12 A/s pulse rise time. Technique to determine low inductances as applied to PC6 elements is described. The described PC6 is used for experiments on generation of super-strong pulse magnetic fields in single-loop solenoid with volume occupied by magnetic field, 5-7 mm. Magnetic field with up to 350 T induction amplitude is obtained in these experiments

  16. Design of motor induction 3-Phase from waste industry to generator for microhydro at isolated village

    Science.gov (United States)

    Rimbawati; Azis Hutasuhut, Abdul; Irsan Pasaribu, Faisal; Cholish; Muharnif

    2017-09-01

    There is an electric machine that can operate as a generator either single-phase or three-phase in almost every household and industry today. This electric engine cannot be labeled as a generator but can be functioned as a generator. The machine that is mentioned is “squirrel cage motors” or it is well-known as induction motor that can be found in water pumps, washing machines, fans, blowers and other industrial machines. The induction motor can be functioned as a generator when the rotational speed of the rotor is made larger than the speed of the rotary field. In this regard, this study aims to modify the remains of 3-phase induction motor to be a permanent generator. Data of research based conducted on the river flow of Rumah Sumbul Village, STM Hulu district of Deli Serdang. The method of this research is by changing rotor and stator winding on a 3 phase induction motor, so it can produce a generator with rotation speed of 500 rpm. Based on the research, it can be concluded that the output voltage generator has occurred a voltage drop 10% between before and after loading for Star circuit and 2% for Delta circuit.

  17. Control System for Producing Electricity with Dual Stator Winding Cage-Rotor Induction Generator

    Directory of Open Access Journals (Sweden)

    Lucian Nicolae Tutelea

    2014-09-01

    Full Text Available This paper will present the key design equations and control design model of the Dual Stator Winding Cage-Rotor Induction Generator (DSWIG to achieve wide-speed-range operation with reduced capacity of the static power controller for low power wind or hydro applications. The proposed induction generator consists of a standard squirrel-cage rotor and a stator with two separate windings wound for a similar number of poles. Moreover, the system control strategy using the stator flux orientation is consequently proposed. The aim of the paper is to emphasize that the low speed induction generators with power electronic converters represent a realistic and useful solution for direct drive power applications.

  18. INVESTIGATION ON ESTABLISHED OPERATIONAL MODES OF FREQUENCY-CONTROLLED INDUCTION GENERATOR OF WIND POWER PLANTS

    Directory of Open Access Journals (Sweden)

    R. I. Mustafayev

    2014-01-01

    Full Text Available The paper proposes an analytical expression for calculating a manipulated variable of stator voltage in a frequency-controlled induction generator with a cage rotor of a wind power plant while regulating a constant value of the absolute slip of the generator. Comparison of the calculated results by the proposed expression and full differential equations of the generator (an equation of state at steady state has confirmed a high accuracy of the analytical expression.

  19. Stabilization of Voltage Parameters of Induction Generator Excited by a Voltage Inverter

    Directory of Open Access Journals (Sweden)

    Padalko D.A.

    2017-12-01

    Full Text Available The article reveals the operational aspects of induction generator. Methods for stabilization of induction generator (IG parameters under inverter excitation are investigated. The study was carried out using mathematical description and simulation modeling in MATLAB Simulink. The paper provides analysis of causes of generated voltage amplitude and frequency displacement when the loading condition and the rate vary. Due to the parametric resonance nature of IG self-excitation, the author introduces the expression that allows estimating the capacitor capacitance required to maintain the generation process, depending on the rotor speed of electric machine, load nature and rate. Based on the studies, it was proved that it is possible to stabilize the IG voltage parameters by maintaining the magnetizing circuit inductance Lm at the constant level., and realizing a control law close to U/f = const. The study proves that using the inverter together with the voltage regulator allows ensuring the quality of electricity corresponding to modern standards. The necessity of problem solving of the required quality of the voltage by the harmonic component for the exciter - inverter with PWM is shown. The prospects of the power generation system based on induction machine (IM with a semiconductor frequency converter, which serves as an adjustable supplier of capacitive current for IM for autonomous objects, are substantiated. The use of semiconductor frequency converters makes it possible to provide high stability of the output voltage parameters and good speed of the mechatronic generation system with an asynchronous machine.

  20. Analog Amplitude Modulation of a High Voltage, Solid State Inductive Adder, Pulse Generator Using MOSFETS

    International Nuclear Information System (INIS)

    Gower, E J; Sullivan, J S

    2002-01-01

    High voltage, solid state, inductive adder, pulse generators have found increasing application as fast kicker pulse modulators for charged particle beams. The solid state, inductive adder, pulse generator is similar in operation to the linear induction accelerator. The main difference is that the solid state, adder couples energy by transformer action from multiple primaries to a voltage summing stalk, instead of an electron beam. Ideally, the inductive adder produces a rectangular voltage pulse at the load. In reality, there is usually some voltage variation at the load due to droop on primary circuit storage capacitors, or, temporal variations in the load impedance. Power MOSFET circuits have been developed to provide analog modulation of the output voltage amplitude of a solid state, inductive adder, pulse generator. The modulation is achieved by including MOSFET based, variable subtraction circuits in the multiple primary stack. The subtraction circuits can be used to compensate for voltage droop, or, to tailor the output pulse amplitude to provide a desired effect in the load. Power MOSFET subtraction circuits have been developed to modulate short, temporal (60-400 ns), voltage and current pulses. MOSFET devices have been tested up to 20 amps and 800 Volts with a band pass of 50 MHz. An analog modulation cell has been tested in a five cell high, voltage adder stack

  1. Capacitive VAr requirements for wind driven self-excited induction generators

    International Nuclear Information System (INIS)

    Singaravelu, S.; Velusami, S.

    2007-01-01

    This paper presents the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, used as isolated power sources by a constant speed or a variable speed prime mover, to obtain the desired voltage regulation at various values of load and speed. Different performance criteria such as constant terminal voltage or constant air gap flux have been considered. The developed mathematical model using nodal analysis based on graph theory is quite general in nature and can be used for any combination of the unknown variables such as magnetizing reactance (X M ) and frequency (F) or capacitive reactance (X C ) and frequency (F) or capacitive reactance (X C ) and speed (υ). The proposed model completely avoids the tedious and erroneous manual work of segregating the real and imaginary components of the complex impedance of the machine for deriving the specific model for each operating modes. Moreover, any element, like the core loss component, can be included or excluded from the model if required. Next, to obtain the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, a fuzzy logic approach is used for the first time to find the unknown variables using the above model. The results are presented in a normalized form so that they are valid for a wide range of machines and would be useful for the design of voltage regulators for such generators

  2. Analysis of synchronous and induction generators used at hydroelectric power plant

    Science.gov (United States)

    Diniş, C. M.; Popa, G. N.; lagăr, A.

    2017-01-01

    In this paper is presented an analysis of the operating electric generators (synchronous and induction) within a small capacity hydroelectric power plant. Such is treated the problem of monitoring and control hydropower plant using SCADA systems. Have been carried an experimental measurements in small hydropower plant for different levels of water in the lake and various settings of the operating parameters.

  3. Modeling of Self-Excited Isolated Permanent Magnet Induction Generator Using Iterative Numerical Method

    Directory of Open Access Journals (Sweden)

    Mohamed Mostafa R.

    2016-01-01

    Full Text Available Self-Excited Permanent Magnet Induction Generator (PMIG is commonly used in wind energy generation systems. The difficulty of Self-Excited Permanent Magnet Induction Generator (SEPMIG modeling is the circuit parameters of the generator vary at each load conditions due to the a change in the frequency and stator voltage. The paper introduces a new modeling for SEPMIG using Gauss-sidle relaxation method. The SEPMIG characteristics using the proposed method are studied at different load conditions according to the wind speed variation, load impedance changes and different shunted capacitor values. The system modeling is investigated due to the magnetizing current variation, the efficiency variation, the power variation and power factor variation. The proposed modeling system satisfies high degree of simplicity and accuracy.

  4. Reactive power generation in high speed induction machines by continuously occurring space-transients

    Science.gov (United States)

    Laithwaite, E. R.; Kuznetsov, S. B.

    1980-09-01

    A new technique of continuously generating reactive power from the stator of a brushless induction machine is conceived and tested on a 10-kw linear machine and on 35 and 150 rotary cage motors. An auxiliary magnetic wave traveling at rotor speed is artificially created by the space-transient attributable to the asymmetrical stator winding. At least two distinct windings of different pole-pitch must be incorporated. This rotor wave drifts in and out of phase repeatedly with the stator MMF wave proper and the resulting modulation of the airgap flux is used to generate reactive VA apart from that required for magnetization or leakage flux. The VAR generation effect increases with machine size, and leading power factor operation of the entire machine is viable for large industrial motors and power system induction generators.

  5. A novel proposal of cooperation between a cage induction generator and the three-phase grid

    Directory of Open Access Journals (Sweden)

    Szular Zbigniew

    2016-01-01

    Full Text Available In the paper, a new concept of the cooperation between a cage induction generator and the three-phase grid is presented. The induction generator is excited by a capacitor battery connected to the stator winding terminals. In order to ensure a stable operation, the battery capacity should be continuously adjusted. Three appropriate selected capacitors are connected to the stator winding terminals by means of two bi-directional controlled switches. The generator output voltage is stabilized by a suitable control of these switches. The stator winding terminals are also connected to the diode bridge rectifier. Energy in the DC bus is converted to the parameters of the three-phase grid (400 V, 50 Hz by means of a three-phase voltage source inverter. Examples of numerical calculation results of the proposed energy generation system are presented in the end part of the paper.

  6. A Vertical-Axis Off-Grid Squirrel-Cage Induction Generator Wind Power System

    Directory of Open Access Journals (Sweden)

    Peifeng Xu

    2016-10-01

    Full Text Available In order to broaden the limited utilization range of wind power and improve the charging and discharging control performance of the storage battery in traditional small wind power generation systems, a wind power system based on a vertical-axis off-grid induction generator is proposed in this paper. The induction generator not only can run in a wide wind speed range but can also assist the vertical-axis wind turbine to realize self-starting at low wind speed. Combined with the maximum power point tracking method, the slip frequency control strategy is employed to regulate the pulse width modulation (PWM converter to control the output power of the proposed system when the wind speed and load change. The charge and discharge of the storage battery is realized by the segmented current-limiting control strategy by means of an electric power unloader device connected to the DC bus. All these implement a balanced and stable operation of the proposed power generation system. The experimental research on the 5.5 kW prototype system is developed, and the corresponding results verify the correctness and feasibility of the system design and control strategy. Some comparison experiments with a magnetic suspension permanent magnet synchronous generator (PMSG demonstrate the application prospect of the proposed vertical-axis off-grid induction generator wind power system.

  7. Voltage and frequency control of wind-powered islanded microgrids based on induction generator and STATCOM

    DEFF Research Database (Denmark)

    Bouzid, Allal; Sicard, Pierre; Guerrero, Josep M.

    2015-01-01

    This paper presents a comprehensive modeling of a three-phase cage induction machine used as a self-excited squirrel-cage induction generator (SEIG), and discusses the regulation of the voltage and frequency of a self-excited SEIG based on the action of the static synchronous Compensator (STATCOM......). The STATCOM with the proposed controller consists of a three-phase voltage-sourced inverter and a DC voltage. The compensator can provide the active and reactive powers and regulate AC system bus voltage and the frequency, but also may enhance the load stability. Moreover, a feed forward control method...

  8. Generation of hydrogen free radicals from water for fuels by electric field induction

    International Nuclear Information System (INIS)

    Nong, Guangzai; Chen, Yiyi; Li, Ming; Zhou, Zongwen

    2015-01-01

    Highlights: • Hydrogen free radicals are generated from water splitting. • Hydrogen fuel is generated from water by electric field induction. • Hydrocarbon fuel is generated from CO_2 and water by electric field induction. - Abstract: Water is the most abundant resource for generating hydrogen fuel. In addition to dissociating H"+ and "−OH ions, certain water molecules dissociate to radicals under an electric field are considered. Therefore, an electric field inducing reactor is constructed and operated to generate hydrogen free radicals in this paper. Hydrogen free radicals begin to be generated under a 1.0 V electric field, and increasing the voltage and temperature increases the number of hydrogen free radicals. The production rate of hydrogen free radicals is 0.245 mmol/(L h) at 5.0 V and room temperature. The generated hydrogen free radicals are converted to polymer fuel and hydrogen fuel at production rates of 0.0093 mmol/(L h) and 0.0038 mmol/(L h) respectively, under 5.0 V and 0.25 mA. The results provide a way to generate hydrogen free radicals, which might be used to generate hydrocarbon fuel in industrial manufacture.

  9. State-space modeling of the radio frequency inductively-coupled plasma generator

    International Nuclear Information System (INIS)

    Dewangan, Rakesh Kumar; Punjabi, Sangeeta B; Mangalvedekar, H A; Lande, B K; Joshi, N K; Barve, D N

    2010-01-01

    Computational fluid dynamics models of RF-ICP are useful in understanding the basic transport phenomenon in an ICP torch under a wide variety of operating conditions. However, these models lack the ability to evaluate the effects of the plasma condition on the RF generator. In this paper, simulation of an induction plasma generator has been done using state space modelling by considering inductively coupled plasma as a part of RF network .The time dependent response of the RF-ICP generator circuit to given input excitation has been computed by extracting the circuit's state-space variables and their constraint matrices. MATLAB 7.1 software has been used to solve the state equations. The values of RF coil current, frequency and plasma power has been measured experimentally also at different plate bias voltage. The simulated model is able to predict RF coil current, frequency, plasma power, overall efficiency of the generator. The simulated and measured values are in agreement with each other. This model can prove useful as a design tool for the Induction plasma generator.

  10. Preparing for what might happen: An episodic specificity induction impacts the generation of alternative future events.

    Science.gov (United States)

    Jing, Helen G; Madore, Kevin P; Schacter, Daniel L

    2017-12-01

    A critical adaptive feature of future thinking involves the ability to generate alternative versions of possible future events. However, little is known about the nature of the processes that support this ability. Here we examined whether an episodic specificity induction - brief training in recollecting details of a recent experience that selectively impacts tasks that draw on episodic retrieval - (1) boosts alternative event generation and (2) changes one's initial perceptions of negative future events. In Experiment 1, an episodic specificity induction significantly increased the number of alternative positive outcomes that participants generated to a series of standardized negative events, compared with a control induction not focused on episodic specificity. We also observed larger decreases in the perceived plausibility and negativity of the original events in the specificity condition, where participants generated more alternative outcomes, relative to the control condition. In Experiment 2, we replicated and extended these findings using a series of personalized negative events. Our findings support the idea that episodic memory processes are involved in generating alternative outcomes to anticipated future events, and that boosting the number of alternative outcomes is related to subsequent changes in the perceived plausibility and valence of the original events, which may have implications for psychological well-being. Published by Elsevier B.V.

  11. Improvement of low speed induction generator performances and reducing the power of excitation and voltage control system

    Energy Technology Data Exchange (ETDEWEB)

    Budisan, N. [Politechnica Univ. of Timisoara (Romania); Hentea, T.; Mahil, S. [Purdue Univ. Calumet, Hammond, IN (United States); Madescu, G. [Romanian Academy, Timisoara (Romania)

    1996-12-31

    In this paper we present the results of our investigations concerning the utilization of induction generators at very low speed. It is shown that, by proper design, it is possible to obtain high efficiency and high power factor values. The optimized induction generators require lower reactive power resulting in lower size and price of the excitation control system. 4 refs., 2 figs.

  12. End Effects on the Linear Induction MHD Generator Calculated by Two-Sided Laplace Transform

    Energy Technology Data Exchange (ETDEWEB)

    Engeln, F.; Peschka, W. [Deutsche Versuchsanstalt fuer Luft- und Raumfahrt e.V., Institut fuer Energiewandlung und Elektrische Antriebe, Stuttgart, Federal Republic of Germany (Germany)

    1966-11-15

    In induction MHD systems special problems occur where the flow enters or leaves the magnetic field. These problems are generally described as end effects. Large gradients of the magnetic field are present at the inlet and also at the outlet of an MHD induction engine, these generating electric current systems in the fluid which may spoil the performance characteristics of the generator due to the interaction with the primary field of the engine. The two-dimensional induction MHD generator of finite length, using a polyphase winding system to obtain a travelling magnetic field, is treated as a boundary value problem by two-sided Laplace transform. For simplicity incompressibility is assumed. The two- dimensional boundary value problem of the induction engine is solved for - {infinity} Less-Than-Over-Equal-To x Less-Than-Over-Equal-To {infinity}. x is parallel to the flow direction of the linear MHD generator. In the region 0 Less-Than-Over-Equal-To x Less-Than-Over-Equal-To L the magnetic travelling wave is sinusoidal with a cyclical frequency {omega} and a phase-velocity v{sub s}. At x = 0 the conducting incompressible working fluid enters the field region and leaves it at the point-x = L. Two mathematical methods can be used to solve the boundary value problem, the Fourier transform or the two-sided Laplace transform. The latter offers the advantage of representing a complex analytical function in the image space. Moreover, it is possible to obtain the characteristics of the generator in the image space (e. g. field configuration, power flow function, etc.). That implies a large simplification of mathematical treatment. The solution in the original space then is given by asymptotic expansion of the known image function. (author)

  13. High-voltage many-pulses generator with inductive energy store and fuse

    International Nuclear Information System (INIS)

    Kovalev, V.P.; Diyankov, V.S.; Kormilitsin, A.I.; Lavrent'ev, B.N.

    1996-01-01

    The high-voltage generator with inductive energy store and fuses as opening switch that generate series of powerful pulses is considered. This generator differs from the ordinary generator with inductive store by the cross-section of the series copper wires. The parameters of the wires are chosen based on empirical relations. The generation principle was tested on the two high-voltage generators with characteristic impedance 2.2 ohm, 4 ohm and with output voltages of 140 kV and 420 kV, respectively. Copper wires 0.1 to 0.23 mm in diameter were used. Series of 2 to 5 pulses of 100 to 300 ns duration, 400 to 1000 kV amplitude and 1 - 10 GW power were obtained. Pulses can be both the same and different. Two successive bremsstrahlung radiation pulses were obtain on the EMIR-M and IGUR-3 devices. Series power megavolt pulses can be generated with a power exceeding 10 11 W, pulse duration of 10 -3 to 10 -6 s, and time interval between them 10 -7 to 10 -5 s. (author). 4 figs., 2 refs

  14. High-voltage many-pulses generator with inductive energy store and fuse

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, V P; Diyankov, V S; Kormilitsin, A I; Lavrent` ev, B N [All-Russian Research Inst. of Technical Physics, Snezhinsk (Russian Federation)

    1997-12-31

    The high-voltage generator with inductive energy store and fuses as opening switch that generate series of powerful pulses is considered. This generator differs from the ordinary generator with inductive store by the cross-section of the series copper wires. The parameters of the wires are chosen based on empirical relations. The generation principle was tested on the two high-voltage generators with characteristic impedance 2.2 ohm, 4 ohm and with output voltages of 140 kV and 420 kV, respectively. Copper wires 0.1 to 0.23 mm in diameter were used. Series of 2 to 5 pulses of 100 to 300 ns duration, 400 to 1000 kV amplitude and 1 - 10 GW power were obtained. Pulses can be both the same and different. Two successive bremsstrahlung radiation pulses were obtain on the EMIR-M and IGUR-3 devices. Series power megavolt pulses can be generated with a power exceeding 10{sup 11} W, pulse duration of 10{sup -3} to 10{sup -6} s, and time interval between them 10{sup -7} to 10{sup -5} s. (author). 4 figs., 2 refs.

  15. Induction generator model in phase coordinates for fault ride-through capability studies of wind turbines

    DEFF Research Database (Denmark)

    Fajardo, L.A.; Iov, F.; Medina, R.J.A.

    2007-01-01

    A phase coordinates induction generator model with time varying electrical parameters as influenced by magnetic saturation and rotor deep bar effects, is presented in this paper. The model exhibits a per-phase formulation, uses standard data sheet for characterization of the electrical parameters...... are conducted in a representative sized system and results show aptness of the proposed model over other two models. This approach is also constructive to support grid code requirements....

  16. Development of the Electromagnetic Induction Type Micro Air Turbine Generator Using MEMS and Multilayer Ceramic Technology

    International Nuclear Information System (INIS)

    Iiduka, A; Ishigaki, K; Takikawa, Y; Ohse, T; Saito, K; Uchikoba, F

    2011-01-01

    The miniaturized electromagnetic induction type air turbine generator is described. The micro air turbine generator rotated by the compressed air and generating electricity was fabricated by the combination of MEMS and multilayer ceramic technology. The micro generator consisted of an air turbine and a magnetic circuit. The turbine part consisted of 7 silicon layers fabricated by the MEMS technology. The magnetic circuit was fabricated by the multilayer ceramic technology based on the green sheet process. The magnetic material used in the circuit was ferrite, and the internal conductor was silver. The dimensions of the obtained generator were 3.5x4x3.5 mm. The output power was 1.92 μW. From FEM analysis of the magnetic flux, it was found that leakage of the flux affected the output power.

  17. Effects of Capcitor Bank on Fault Ride Through Capibility of Induction Generator Based Wind Turbines

    DEFF Research Database (Denmark)

    Hu, Y; Chen, Zhe

    2010-01-01

    power system stability and supply security. Some existing wind turbines are still based on fixed speed induction generators, the effects of capacitor bank on such generators are discussed in this paper. The simulation study shows the capacitor bank may costeffectively improve the dynamic performance......Wind turbine installation is increasing rapidly. In some networks, wind power penetration is significantly high and the performance of wind turbine plays an important role in power system operation and control. Especially, the behavior of wind turbines during a power system disturbance would affect...

  18. Study on the plasma generation characteristics of an induction-triggered coaxial pulsed plasma thruster

    Science.gov (United States)

    Weisheng, CUI; Wenzheng, LIU; Jia, TIAN; Xiuyang, CHEN

    2018-02-01

    At present, spark plugs are used to trigger discharge in pulsed plasma thrusters (PPT), which are known to be life-limiting components due to plasma corrosion and carbon deposition. A strong electric field could be formed in a cathode triple junction (CTJ) to achieve a trigger function under vacuum conditions. We propose an induction-triggered electrode structure on the basis of the CTJ trigger principle. The induction-triggered electrode structure could increase the electric field strength of the CTJ without changing the voltage between electrodes, contributing to a reduction in the electrode breakdown voltage. Additionally, it can maintain the plasma generation effect when the breakdown voltage is reduced in the discharge experiments. The induction-triggered electrode structure could ensure an effective trigger when the ablation distance of Teflon increases, and the magnetic field produced by the discharge current could further improve the plasma density and propagation velocity. The induction-triggered coaxial PPT we propose has a simplified trigger structure, and it is an effective attempt to optimize the micro-satellite thruster.

  19. Active Power and Flux Control of a Self-Excited Induction Generator for a Variable-Speed Wind Turbine Generation

    Energy Technology Data Exchange (ETDEWEB)

    Na, Woonki; Muljadi, Eduard; Leighty, Bill; Kim, Jonghoon

    2017-05-11

    A Self-Excited Induction Generation (SEIG) for a variable speed wind turbine generation(VS-WG) is normally considered to be a good candidate for implementation in stand-alone applications such as battery charging, hydrogenation, water pumping, water purification, water desalination, and etc. In this study, we have examined a study on active power and flux control strategies for a SEIG for a variable speed wind turbine generation. The control analysis for the proposed system is carried out by using PSCAD software. In the process, we can optimize the control design of the system, thereby enhancing and expediting the control design procedure for this application. With this study, this control design for a SEIG for VS-WG can become the industry standard for analysis and development in terms of SEIG.

  20. Torque control of synchronous and induction generators for variable speed operation of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Ola; Ulen, E. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    The aim of this paper is to investigate variable speed electrical systems. Synchronous generators with diode rectifiers and line-commutated thyristor converters are compared with induction generators with force commutated transistor converters and scalar control. The system characteristics are examined regarding possible speed of response (bandwidth) of the torque control, including the sensitivity to disturbances for the drive train and also the possibility to get damping of the drive train resonance. Analyses, simulations and laboratory tests with a 40 kW machine set-up have been performed. The investigation shows that the system with synchronous generator is well suited for wind power applications. A rapid standard DC-current regulator is included in the torque control and can be used for damping of the resonance. The torque control has a bandwidth up to about 3 Hz and the DC-voltage controller up to about 1 Hz. The system with induction generator with scalar control (no transformations) is more difficult to control. A linear approach is only possible up to about 1.5 Hz. In this region it turns out that the behaviour can be visualized as an added inertia on the generator side that can be rather big. 4 refs, 9 figs

  1. Controller for a small induction-generator based wind-turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ahshan, R.; Iqbal, M.T.; Mann, George K.I. [Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John' s, Newfoundland (Canada)

    2008-04-15

    Design of a low-cost micro-controller for a small induction-generator based grid-connected wind-turbine is presented in this paper. The controller senses the parameters of the wind-turbine generator and the grid, and makes decisions about grid connection and disconnection. Low-cost instrumentation circuitry has been developed to measure the generator and grid parameters. Based on the measurement of voltage and frequency of the wind-turbine generator and the grid side, a control decision is taken to connect the system to the grid. The controller makes decision to disconnect the system from the grid based on the power flow measurement between the wind turbine and the grid. The power flow between wind turbine and the grid depends upon the availability of the wind. The prototype controller has been developed based on a micro-controller PIC16F877 and has been tested in the laboratory. (author)

  2. Supercapacitor energy storage system for fault ride-through of a DFIG wind generation system

    International Nuclear Information System (INIS)

    Rahim, A.H.M.A.; Nowicki, E.P.

    2012-01-01

    Highlights: ► A detailed dynamic model of a DFIG is developed to study the low voltage ride-through phenomenon. ► A supercapacitor-STATCOM energy storage system is employed. ► Decoupled real and reactive power control strategies implemented on the system. ► The proposed controller show extremely good transient behavior following low voltage conditions. - Abstract: The doubly fed induction generators (DFIGs) are preferred over other variable speed generators because of their advantages in terms of economy and control. One of the problems associated with high wind power penetration DFIG systems, however, is the inability of their converters to work properly under extreme low voltage conditions. This article presents a decoupled P–Q control strategy of a supercapacitor energy storage system, interfaced through a STATCOM, for low voltage ride through as well as damping enhancement of the DFIG system. The STATCOM meets the reactive power need under the depressed voltage condition, while the supercapacitor caters to the real power unbalance. An extensive dynamic model of the DFIG system including a supercapacitor DC–DC buck–boost converter and the STATCOM circuit has been developed. The fault ride-thorough capability of the generator has been investigated for a severe symmetrical three-phase to ground fault on the grid bus. Simulation results suggest that the proposed decoupled control of the supercapacitor STATCOM control strategy can help the DFIG ride through extreme low voltage conditions for significant duration. The proposed control strategy also damps the electromechanical transients, and thus quickly restores normal operation of the converters.

  3. Investigation on magnetoacoustic signal generation with magnetic induction and its application to electrical conductivity reconstruction

    International Nuclear Information System (INIS)

    Ma Qingyu; He Bin

    2007-01-01

    A theoretical study on the magnetoacoustic signal generation with magnetic induction and its applications to electrical conductivity reconstruction is conducted. An object with a concentric cylindrical geometry is located in a static magnetic field and a pulsed magnetic field. Driven by Lorentz force generated by the static magnetic field, the magnetically induced eddy current produces acoustic vibration and the propagated sound wave is received by a transducer around the object to reconstruct the corresponding electrical conductivity distribution of the object. A theory on the magnetoacoustic waveform generation for a circular symmetric model is provided as a forward problem. The explicit formulae and quantitative algorithm for the electrical conductivity reconstruction are then presented as an inverse problem. Computer simulations were conducted to test the proposed theory and assess the performance of the inverse algorithms for a multi-layer cylindrical model. The present simulation results confirm the validity of the proposed theory and suggest the feasibility of reconstructing electrical conductivity distribution based on the proposed theory on the magnetoacoustic signal generation with magnetic induction

  4. Control and Analysis for a Self-Excited Induction Generator for Wind Turbine and Electrolyzer Applications

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Na, Woonki [California State University, Fresno; Leighty, Bill [The Leighty Foundation; Kim, Jonghoon [Chungnam National University

    2017-12-14

    Self-Excited Induction Generation(SEIG) is very rugged, simple, lightweight, and it is easy and inexpensive to implement, very simple to control, and requires a very little maintenance. In this variable-speed operation, the SEIG needs a power electronics interface to convert from the variable frequency output voltage of the generator to a DC output voltage for battery or other DC applications. In our study, a SEIG is connected to the power electronics interface such as diode rectifier and DC/DC converter and then an electrolyzer is connected as a final DC load for fuel cell applications. An equivalent circuit model for an electrolyzer is utilized for our application. The control and analysis for the proposed system is carried out by using PSCAD and MATLAB software. This study would be useful for designing and control analysis of power interface circuits for SEIG for a variable speed wind turbine generation with fuel cell applications before the actual implementation.

  5. Analysis and estimation of transient stability for a grid-connected wind turbine with induction generator

    DEFF Research Database (Denmark)

    Li, H.; Zhao, B.; Yang, C.

    2011-01-01

    based on normal form theory is proposed. The transient models of the wind turbine generation system including the flexible drive train model are derived based on the direct transient stability estimation method. A method of critical clearing time (CCT) calculation is developed for the transient......Increasing levels of wind energy in modern electrical power system is initiating a need for accurate analysis and estimation of transient stability of wind turbine generation systems. This paper investigates the transient behaviors and possible direct methods for transient stability evaluation...... of a grid-connected wind turbine with squirrel cage induction generator (SCIG). Firstly, by using an equivalent lump mass method, a three-mass wind turbine equivalent model is proposed considering both the blades and the shaft flexibility of the wind turbine drive train system. Combined with the detailed...

  6. Yield and power of the induction motor operating as generator; Rendimento e potencia do motor de inducao atuando como gerador

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Francisco de Salles Cintra [Universidade Paulista (UNIP), Campinas, SP (Brazil)

    1997-12-01

    This article shows the result of the analysis of two induction motors operating as generators (Park variable for a machine connected to an infinite bar), particularly the yield and power of the machines operating under this condition.

  7. Technology of VAr Compensators for Induction Generator Applications in Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    A. F. Zobaa

    2006-09-01

    Full Text Available Many of today utility interconnected wind farms use induction generator (IG to convert the captured wind mechanical power into electricity. Induction generator has some advantages over the synchronous generator (SG. The main advantages are its robustness and its capability to be synchronized directly to the grid. The main disadvantage, however, is its dependency on the grid for supplying its own reactive power ‘VAr’. Whether fixed or adjustable VAr systems are connected across its terminal, IG must operate at unity power factor at the rated loading while the wind power varies. With supervised control and appropriate coordination, VAr can be used to the benefits of both the wind farm developer and the hosting utility. The incorporation of today adjustable reactive power compensators such as the Static VAr Compensation (SVC and Static Synchronous Compensator (STATCOM with IG are vital ingredient toward a successful penetration of wind energy in today distribution grid to ensure voltage stability during the steady state and transient periods.

  8. Induction heating to trigger the nickel surface modification by in situ generated 4-carboxybenzene diazonium

    Science.gov (United States)

    Arrotin, Bastien; Jacques, Amory; Devillers, Sébastien; Delhalle, Joseph; Mekhalif, Zineb

    2016-05-01

    Nickel is commonly used in numerous applications and is one of the few materials that present strong ferromagnetic properties. These make it a suitable material for induction heating which can be used to activate the grafting of organic species such as diazonium salts onto the material. Diazonium compounds are often used for the modification of metals and alloys thanks to their easy chemical reduction onto the substrates and the possibility to apply a one-step in situ generation process of the diazonium species. This work focuses on the grafting of 4-aminocarboxybenzene on nickel substrates in the context of a spontaneous grafting conducted either at room temperature or by thermal assistance through conventional heating and induction heating. These modifications are also carried out with the goal of maintaining the oxides layer as much as possible unaffected. The benefits of using induction heating with respect to conventional heating are an increase of the grafting rate, a better control of the reaction and a slighter impact on the oxides layer.

  9. Modeling and Simulation of a Wind Turbine Driven Induction Generator Using Bond Graph

    Directory of Open Access Journals (Sweden)

    Lachouri Abderrazak

    2015-12-01

    Full Text Available The objective of this paper is to investigate the modelling and simulation of wind turbine applied on induction generator with bond graph methodology as   a graphical and multi domain approach. They provide a precise and unambiguous modelling tool, which allows for the specification of hierarchical physical structures. The paper begins with an introduction to the bond graphs technique, followed by an implementation of the wind turbine model. Simulation results illustrate the simplified system response obtained using the 20-sim software.

  10. Process for the generation of high capacity pulses from an inductive energy storage device

    International Nuclear Information System (INIS)

    Maier, F.; Maier, S.

    1984-01-01

    An inductive storage circuit for generating high voltage pulses includes a quenching circuit and a discharge circuit each connected in parallel with a storage inductor. One branch of the quenching circuit includes a quenching capacitor and one branch of the discharge circuit includes a resistor and a diode in series. These two branches have a common junction, to which is connected a quenching thyristor that forms the second branch of each of the quenching and discharge circuits. Thus, the quenching thyristor is in series with each of the quenching capacitor and the discharge resistor

  11. Operation of LIA-30 linear induction accelerator in the mode of generation of two bremsstrahlung pulses

    Energy Technology Data Exchange (ETDEWEB)

    Bossamykin, V S; Gerasimov, A I; Gordeev, V S; Grishin, A V; Gritsina, V P; Tarasov, A D; Fedotkin, A S; Lazarev, S A; Averchenkov, A Ya [All-Russian Scientific Research Institute of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    The operating mode was studied of the LIA-30 linear induction accelerator ({approx} 40 MeV, {approx} 100 kA, {approx} 30 ns) with the generation of two bremsstrahlung pulses separated by a specified time interval from 0 to 5 {mu}s. In the accelerating channel an additional tube cathode was installed, and a synchronization system for two accelerating module groups triggering the formation and acceleration, at different initial times, of two annular electron beams with different outer diameters was changed. The energy limit of each beam electron acceleration can be controlled, and the energy sum limit is {<=} 540 MeV. (author). 2 tabs., 2 figs.

  12. Stochastic reactive power dispatch in hybrid power system with intermittent wind power generation

    International Nuclear Information System (INIS)

    Taghavi, Reza; Seifi, Ali Reza; Samet, Haidar

    2015-01-01

    Environmental concerns besides fuel costs are the predominant reasons for unprecedented escalating integration of wind turbine on power systems. Operation and planning of power systems are affected by this type of energy due to the intermittent nature of wind speed inputs with high uncertainty in the optimization output variables. Consequently, in order to model this high inherent uncertainty, a PRPO (probabilistic reactive power optimization) framework should be devised. Although MC (Monte-Carlo) techniques can solve the PRPO with high precision, PEMs (point estimate methods) can preserve the accuracy to attain reasonable results when diminishing the computational effort. Also, this paper introduces a methodology for optimally dispatching the reactive power in the transmission system, while minimizing the active power losses. The optimization problem is formulated as a LFP (linear fuzzy programing). The core of the problem lay on generation of 2m + 1 point estimates for solving PRPO, where n is the number of input stochastic variables. The proposed methodology is investigated using the IEEE-14 bus test system equipped with HVDC (high voltage direct current), UPFC (unified power flow controller) and DFIG (doubly fed induction generator) devices. The accuracy of the method is demonstrated in the case study. - Highlights: • This paper uses stochastic loads in optimization process. • AC–DC load flow is modified to use some advantages of DC part in optimization process. • UPFC and DFIG are simulated in a way that could be effective in optimization process. • Fuzzy set has been used as an uncertainty analysis tool in the optimization

  13. Generation of heat on fuel rod in cosine pattern by using induction heating

    International Nuclear Information System (INIS)

    Keettikkal, Felix; Sajeesh, Divya; Rao, Poornima; Hande, Shashank; Dakave, Ganesh; Kute, Tushar; Mahajan, Akshay; Kulkarni, R.D.

    2017-01-01

    Fuel rods are used in a nuclear reactor for fission process. When these rods are cooled by water during the heat transfer, the temperature stress causes undesirable defects in the fuel rod. Studying these defects occurring in the fuel rod in the nuclear cluster during nuclear reaction is a difficult task because fission reaction makes it difficult to analyse the changes in the rod. Hence there is a need to use a replica of the rod with similar thermal stress to study and analyse the rod for the defects. Normally the heat generated on the fuel rod follows a cosine pattern which is an inherent characteristic inside a nuclear reactor. In view of this, in this paper induction heating method is used on a rod to create an exact replica of the cosine pattern of heat by varying the pitch of the coil. First, a MATLAB simulation is done using simulink. Then a prototype of the model has been developed comprising of carbon steel pipe, with length and outside diameter of 1 meter and 48.2 mm, respectively. Instead of using water as coolant, rod is simulated in air. Therefore, the heat generated is lost by normal convection and radiation. Non-nuclear testing can be a valuable tool in the development or in some kind of experiment using nuclear reactor. Induction heating becomes an alternative to classical heating technologies because of its advantages such as efficiency, quickness, safety, clean heating and accurate power control. (author)

  14. Analysis of wind driven self-excited induction generator supplying isolated DC loads

    Directory of Open Access Journals (Sweden)

    Khaled S. Sakkoury

    2017-05-01

    Full Text Available This paper presents the analysis, modelling and simulation of wind-driven self-excited induction generator (SEIG. The three-phase SEIG is driven by a variable-speed prime mover to represent a wind turbine. Also, the paper investigates the dynamic performance of the SEIG during start-up, increasing or decreasing the load or rotor speed. The value of the excitation capacitance required for the SEIG is calculated to give suitable saturation level to assure self-excitation and to avoid heavy saturation levels. Matching of the maximum power available from the wind turbine is performed through varying the load value. The effect of AC–DC power conversion on the generator is investigated. The system simulation is carried out using MATLAB/SIMULINK toolbox program.

  15. Speed-sensorless control strategy for multi-phase induction generator in wind energy conversion systems

    Directory of Open Access Journals (Sweden)

    Dumnić Boris P.

    2016-01-01

    Full Text Available Renewable energy sources, especially wind energy conversion systems (WECS, exhibit constant growth. Increase in power and installed capacity led to advances in WECS topologies. Multi-phase approach presents a new development direction, with several key advantages over three-phase systems. Paired with a sensorless control strategy, multi-phase machines are expected to take primacy over standard solutions. This paper presents speed sensorless vector control of an asymmetrical six-phase induction generator based on a model reference adaptive system (MRAS. Suggested topology and developed control algorithm show that sensorless control can yield appropriate dynamic characteristics for the use in WECS with increase in reliability and robustness. [Projekat Ministarstva nauke Republike Srbije, br. III 042004: Smart Electricity Distribution Grids Based on Distribution Management System and Distributed Generation

  16. MOSFET-based high voltage double square-wave pulse generator with an inductive adder configuration

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xin [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Qiaogen, E-mail: hvzhang@mail.xjtu.edu.cn [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Long, Jinghua [College of Physics, Shenzhen University, Shenzhen 518060 (China); Lei, Yunfei; Liu, Jinyuan [Institute of Optoelectronics, Shenzhen University, Shenzhen 518060 (China)

    2015-09-01

    This paper presents a fast MOSFET-based solid-state pulse generator for high voltage double square-wave pulses. The generator consists mainly of an inductive adder system stacked of 20 solid-state modules. Each of the modules has 18 power MOSFETs in parallel, which are triggered by individual drive circuits; these drive circuits themselves are synchronously triggered by a signal from avalanche transistors. Our experiments demonstrate that the output pulses with amplitude of 8.1 kV and peak current of about 405 A are available at a load impedance of 20 Ω. The pulse has a double square-wave form with a rise and fall time of 40 ns and 26 ns, respectively and bottom flatness better than 12%. The interval time of the double square-wave pulses can be adjustable by varying the interval time of the trigger pulses.

  17. Experimental stand-alone self-excited induction generator driven by a diesel motor

    Directory of Open Access Journals (Sweden)

    Mhamdi Taoufik

    2017-12-01

    Full Text Available This paper presents an experimental work to design and size a diesel generator (DG. The basic system is equipped with a 1.5 kW self-excited induction generator (SEIG, a diesel motor (DM, a static voltage compensator (SVC and controllers. A proportional integral controller is used to meet the requirement of the SEIG frequency regulation. A controlled voltage source is performed by using an SVC with a fuzzy controller, which adjusts voltage by varying the amount of the injected reactive power. An experimental set-up is used to identify the SEIG parameters and select the convenient bank of capacitors that minimize the SEIG starting up time and fix the convenient margin of voltage. The system has been tested by simulation using models implemented by Matlab/Simulink software. The simulation results confirm the efficiency of the proposed strategy of voltage regulation. Keywords: Diesel motor, SEIG, SVC, Voltage regulation, Frequency regulation

  18. ANALYSIS OF THE SPECIAL FEATURES OF THE THERMAL PROCESS IN AN INDUCTION GENERATOR AT HIGH SATURATION OF THE MAGNETIC SYSTEM

    Directory of Open Access Journals (Sweden)

    V. Chenchevoi

    2017-06-01

    Full Text Available Purpose. Development of the method for the assessment of the thermal operation modes of an autonomous electrical power system with an induction motor, aiming at improvement of the reliability of electricity supply and the quality of electric energy. Methodology. Induction generator mathematical modeling taking into account the magnetic system saturation was used in the research. A heat model taking into account the excess of the temperature of the induction generator units in the mode of high saturation was developed. The obtained results were compared with the experimental data. Results. The paper contains the solution to the problem of improvement of the mathematical model sand methods for steel losses determination in there search of the operation modes of an autonomous uncontrolled induction generator taking into consideration the properties of the magnetic system in the mode of high saturation. The expression for determination of steel losses in the mode of high saturation is obtained. It enables the assessment of the induction generator thermal condition. Originality. The analytical dependence for the calculation of the steel losses in the mode of magnetic system saturation has been obtained for the first time. Practical value. The obtained expression for the calculation of the steel losses can be used for determination of the admissible time of generator operation at overload. It will allow avoiding broken winding insulation and complete use of the generator overload capacity. As a result, it will reduce possible irregularities of electricity supply due to the generator preliminary cutoff.

  19. Design and analysis of a dead volume control for a solar Stirling engine with induction generator

    International Nuclear Information System (INIS)

    Beltrán-Chacon, Ricardo; Leal-Chavez, Daniel; Sauceda, D.; Pellegrini-Cervantes, Manuel; Borunda, Mónica

    2015-01-01

    In this work, a power generation system dish/Stirling with cavity receiver and an electrical induction generator was simulated. We propose a control system using a variable-dead-volume and analyze its influence on the mechanical performance. A system with a dead volume of 160 cm"3 was designed to control the power and speed of the engine considering annual insolation, mechanical properties of the heater and the limits of frequency and voltage for the systems interconnected to the electricity network. The designed system achieves net efficient solar conversion to electric of 23.38% at an irradiance of 975 W/m"2 and allows an annual increase of 18% of the useful electrical energy compared to a system without control. - Highlights: • Numerical simulation of a nitrogen charged solar Stirling engine for electric power generation. • Design and analysis of a dead volume control for performance increase and power modulation. • Effect of dead space on average working pressure and mass flow rate. • Comparison between dead volume and average pressure control methods. • Impact of Stirling engine control settings on annual generated electric power.

  20. Fast control strategy for stabilising fixed-speed induction-generator-based wind turbines in an islanded distributed system

    DEFF Research Database (Denmark)

    Wei, Mu; Chen, Zhe

    2013-01-01

    Distributed generation systems (DGS) with fixed-speed induction-generator-based wind turbines (FSWT) are sensitive and vulnerable to voltage disturbances and reactive power deficiency. Consequently, the control and protection strategies for such a DGS should be prompt and precise to avoid undesired...

  1. Status of an induction accelerator driven, high-power microwave generator at Livermore

    International Nuclear Information System (INIS)

    Houck, T.L.; Westenskow, G.A.

    1993-01-01

    The authors are testing an enhanced version of the Choppertron, a high-power rf generator which shows great promise of achieving greater than 400 MW of output power at 11.4 GHz with stable phase and amplitude. This version of the Choppertron is driven by a 5-MeV, 1-kA induction accelerator beam. Modifications to the original Choppertron included aggressive suppression of high order modes in the two output structures, lengthening of the modulation section to match for higher beam energy, and improved efficiency. Final results of the original Choppertron experiment, status of the ongoing experiment and planned experiments for the next year are presented. The motivation of the research program at the LLNL Microwave Source Facility is to develop microwave sources which could be suitable drivers for a future TeV linear e + e - collider

  2. Remembering the past and imagining the future: Selective effects of an episodic specificity induction on detail generation.

    Science.gov (United States)

    Madore, Kevin P; Schacter, Daniel L

    2016-01-01

    According to the constructive episodic simulation hypothesis, remembering past experiences and imagining future experiences both rely heavily on episodic memory. However, recent research indicates that nonepisodic processes such as descriptive ability also influence memory and imagination. We recently found that an episodic specificity induction--brief training in recollecting details of past experiences--enhanced detail generation on memory and imagination tasks but not a picture description task and thereby concluded that the induction can dissociate episodic processes involved in remembering the past and imagining the future from those nonepisodic processes involved in description. To evaluate the generality of our previous findings and to examine the role of generative search in producing those findings, we modified our paradigm so that word cues replaced picture cues, and a word comparison task that requires generation of sentences and word definitions replaced picture description. Young adult participants received either a specificity induction or one of two control inductions before completing the memory, imagination, and word comparison tasks. Replicating and extending our previous work, we found that the specificity induction increased detail generation in memory and imagination without having an effect on word comparison. The induction's selective effect on memory and imagination stemmed from an increase in internal (i.e., on-topic and episodic) details and had no effect on external (e.g., off-topic or semantic) details. The results point to the efficacy of the specificity induction for isolating episodic processes involved in remembering the past and imagining the future even when a nonepisodic task requires generative search.

  3. Vectorial Command of Induction Motor Pumping System Supplied by a Photovoltaic Generator

    Science.gov (United States)

    Makhlouf, Messaoud; Messai, Feyrouz; Benalla, Hocine

    2011-01-01

    With the continuous decrease of the cost of solar cells, there is an increasing interest and needs in photovoltaic (PV) system applications following standard of living improvements. Water pumping system powered by solar-cell generators are one of the most important applications. The fluctuation of solar energy on one hand, and the necessity to optimise available solar energy on the other, it is useful to develop new efficient and flexible modes to control motors that entrain the pump. A vectorial control of an asynchronous motor fed by a photovoltaic system is proposed. This paper investigates a photovoltaic-electro mechanic chain, composed of a PV generator, DC-AC converter, a vector controlled induction motor and centrifugal pump. The PV generator is forced to operate at its maximum power point by using an appropriate search algorithm integrated in the vector control. The optimization is realized without need to adding a DC-DC converter to the chain. The motor supply is also ensured in all insolation conditions. Simulation results show the effectiveness and feasibility of such an approach.

  4. Power Management of Islanded Self-Excited Induction Generator Reinforced by Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Nachat N. Nasser

    2018-02-01

    Full Text Available Self-Excited Induction Generators (SEIGs, e.g., Small-Scale Embedded wind generation, are increasingly used in electricity distribution networks. The operational stability of stand-alone SEIG is constrained by the local load conditions: stability can be achieved by maintaining the load’s active and reactive power at optimal values. Changes in power demand are dependent on customers’ requirements, and any deviation from the pre-calculated optimum setting will affect a machine’s operating voltage and frequency. This paper presents an investigation of the operation of the SEIG in islanding mode of operation under different load conditions, with the aid of batteries as an energy storage source. In this research a current-controlled voltage-source converter is proposed to regulate the power exchange between a direct current (DC energy storage source and an alternating current (AC grid, the converter’s controller is driven by any variation between machine capability and load demand. In order to prolong the system stability when the battery reaches its operation constraints, it is recommended that an ancillary generator and a dummy local load be embedded in the system. The results show the robustness and operability of the proposed system in the islanding mode of the SEIG under different load conditions.

  5. Chapter 10 - Control of Wind Turbine System

    DEFF Research Database (Denmark)

    Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

    2018-01-01

    Wind power is a main pillar of renewable energy supply, as it generates clean and climate-friendly electricity. Among the mainstream wind turbine systems, the configurations of the doubly fed induction generator (DFIG) and the permanent-magnet synchronous generator (PMSG) are dominating and impor...

  6. Chapter 10: Control of Wind Turbine System

    DEFF Research Database (Denmark)

    Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

    2018-01-01

    Wind power is a main pillar of renewable energy supply, as it generates clean and climate-friendly electricity. Among the mainstream wind turbine systems, the configurations of the doubly fed induction generator (DFIG) and the permanent-magnet synchronous generator (PMSG) are dominating and impor...

  7. Software for evaluating magnetic induction field generated by power lines: implementation of a new algorithm

    International Nuclear Information System (INIS)

    Comelli, M.; Benes, M.; Bampo, A.; Villalta, R.

    2006-01-01

    The Regional Environment Protection Agency of Friuli Venezia Giulia (A.R.P.A. F.V.G., Italy) has performed an analysis on existing software designed to calculate magnetic induction field generated by power lines. As far as the agency requirements are concerned the tested programs display some difficulties in the immediate processing of electrical and geometrical data supplied by plant owners, and in certain cases turn out to be inadequate in representing complex configurations of power lines. Furthermore, none of them is preset for cyclic calculus to determine the time evolution of induction in a certain exposure area. Finally, the output data are not immediately importable by ArcView, the G.I.S. used by A.R.P.A. F.V.G., and it is not always possible to implement the territory orography to determine the field at specified heights above the ground. P.h.i.d.e.l., an innovative software, tackles and works out al l the above mentioned problems. The power line wires interested in its implementation are represented by poly lines, and the field is analytically calculated, with no further approximation, not even when more power lines are concerned. Therefore, the obtained results, when compared with those of other programs, are the closest to experimental measurements. The output data can be employed both in G.I.S. and Excel environments, allowing the immediate overlaying of digital cartography and the determining of the 3 and 10 μT bands, in compliance with the Italian Decree of the President of the Council of Ministers of 8 July 2003. (authors)

  8. An optimal reactive power control strategy for a DFIG-based wind farm to damp the sub-synchronous oscillation of a power system

    DEFF Research Database (Denmark)

    Zhao, Bin; Li, Hui; Wang, Mingyu

    2014-01-01

    This study presents the auxiliary damping control with the reactive power loop on the rotor-side converter of doubly-fed induction generator (DFIG)-based wind farms to depress the sub-synchronous resonance oscillations in nearby turbogenerators. These generators are connected to a series capaciti...

  9. The effect of fault ride-through requirements on voltage dips and post-fault voltage recovery in a Dutch distribution network

    NARCIS (Netherlands)

    Karaliolios, P.; Coster, E.J.; Slootweg, J.G.; Kling, W.L.

    2010-01-01

    In this paper the possibility to use Decentralized Generation (DG) units for voltage support in Distribution Networks during and after a Short Circuit (S/C) event is discussed. Two types of DG units will be examined, Combined Heat-Power (CHP) plants and Doubly-Fed Induction Generators (DFIG).

  10. High Frequency Resonance Damping of DFIG based Wind Power System under Weak Network

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    When operating in a micro or weak grid which has a relatively large network impedance, the Doubly Fed Induction Generator (DFIG) based wind power generation system is prone to suffer high frequency resonance due to the impedance interaction between DFIG system and the parallel compensated network...

  11. Analysis of a commercial wind farm in Taiwan

    DEFF Research Database (Denmark)

    Wang, Li; Yeh, Tai-Her; Lee, Wei-Jen

    2010-01-01

    , and simulation results of the studied Jang-Bin wind farm with 23 2-MW doubly fed induction generator-type wind turbine generators connected to the utility system through a 23/161-kV 60-MVA step-up main transformer (MT) from six feeders. Six CLRs, which were originally designed to limit short-circuit currents...

  12. DC Link Current Estimation in Wind-Double Feed Induction Generator Power Conditioning System

    Directory of Open Access Journals (Sweden)

    MARIAN GAICEANU

    2010-12-01

    Full Text Available In this paper the implementation of the DC link current estimator in power conditioning system of the variable speed wind turbine is shown. The wind turbine is connected to double feed induction generator (DFIG. The variable electrical energy parameters delivered by DFIG are fitted with the electrical grid parameters through back-to-back power converter. The bidirectional AC-AC power converter covers a wide speed range from subsynchronous to supersynchronous speeds. The modern control of back-to-back power converter involves power balance concept, therefore its load power should be known in any instant. By using the power balance control, the DC link voltage variation at the load changes can be reduced. In this paper the load power is estimated from the dc link, indirectly, through a second order DC link current estimator. The load current estimator is based on the DC link voltage and on the dc link input current of the rotor side converter. This method presents certain advantages instead of using measured method, which requires a low pass filter: no time delay, the feedforward current component has no ripple, no additional hardware, and more fast control response. Through the numerical simulation the performances of the proposed DC link output current estimator scheme are demonstrated.

  13. Analysis and control of induction generator supplying stand-alone AC loads employing a Matrix Converter

    Directory of Open Access Journals (Sweden)

    Sumedha Mahajan

    2017-04-01

    Full Text Available This paper proposes a Capacitor Excited Induction Generator (CEIG-Matrix Converter (MC system for feeding stand-alone AC loads. The variable output voltage magnitude and frequency from CEIG is converted into a constant voltage magnitude and frequency at the load terminals by controlling MC using Space Vector Modulation (SVM technique. This single-stage MC is turned up as a good alternative for the proposed system against commonly used AC/DC/AC two stage power converters. The configuration and implementation of the closed-loop control scheme employing dSPACE 1103 real time controller have been fully described in the paper. The proposed closed-loop controller regulates the AC load voltage irrespective of changes in the prime mover speed and load. A method for predetermining the steady-state performance of the proposed system has been developed and described with relevant analytical expressions. The effectiveness of the proposed system is exemplified through simulation results for various operating conditions. The proposed control technique is further validated using an experimental setup developed in the laboratory.

  14. Design of an Inductive Adder for the FCC injection kicker pulse generator

    Science.gov (United States)

    Woog, D.; Barnes, M. J.; Ducimetière, L.; Holma, J.; Kramer, T.

    2017-07-01

    The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN.

  15. Dependence of Initial Oxygen Concentration on Ozone Yield Using Inductive Energy Storage System Pulsed Power Generator

    Science.gov (United States)

    Go, Tomio; Tanaka, Yasushi; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

    Dependence of initial oxygen concentration on ozone yield using streamer discharge reactor driven by an inductive energy storage system pulsed power generator is described in this paper. Fast recovery type diodes were employed as semiconductor opening switch to interrupt a circuit current within 100 ns. This rapid current change produced high-voltage short pulse between a secondary energy storage inductor. The repetitive high-voltage short pulse was applied to a 1 mm diameter center wire electrode placed in a cylindrical pulse corona reactor. The streamer discharge successfully occurred between the center wire electrode and an outer cylinder ground electrode of 2 cm inner diameter. The ozone was produced with the streamer discharge and increased with increasing pulse repetition rate. The ozone yield changed in proportion to initial oxygen concentration contained in the injected gas mixture at 800 ns forward pumping time of the current. However, the decrease of the ozone yield by decreasing oxygen concentration in the gas mixture at 180 ns forward pumping time of the current was lower than the decrease at 800 ns forward pumping time of the current. This dependence of the initial oxygen concentration on ozone yield at 180 ns forward pumping time is similar to that of dielectric barrier discharge reactor.

  16. Characterization methods of nano-patterned surfaces generated by induction heating assisted injection molding

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Ravn, Christian; Menotti, Stefano

    2015-01-01

    An induction heating-assisted injection molding (IHAIM) process developed by the authors is used to replicate surfaces containing random nano-patterns. The injection molding setup is developed so that an induction heating system rapidly heats the cavity wall at rates of up to 10◦C/s. In order...

  17. Wind farm models and control strategies

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul; Hansen, Anca D.; Iov, F.; Blaabjerg, F.; Donovan, M.H.

    2005-08-01

    This report describes models and control strategies for 3 different concepts of wind farms. Initially, the potential in improvement of grid integration, structural loads and energy production is investigated in a survey of opportunities. Then simulation models are described, including wind turbine models for a fixed speed wind turbine with active stall control and a variable speed wind turbine with doubly-fed induction generator. After that, the 3 wind farm concepts and control strategies are described. The 3 concepts are AC connected doubly fed turbines, AC connected active stall turbines and DC connected active stall turbines. Finally, some simulation examples and conclusions are presented. (au)

  18. Studies on battery storage requirement of PV fed wind-driven induction generators

    International Nuclear Information System (INIS)

    Rajan Singaravel, M.M.; Arul Daniel, S.

    2013-01-01

    Highlights: ► Sizing of battery storage for PV fed wind-driven IG system is taken up. ► Battery storage is also used to supply reactive power for wind-driven IG. ► Computation of LPSP by incorporating uncertainties of irradiation and wind speed. ► Sizing of hybrid power system components to ensure zero LPSP. ► Calculated storage size satisfied the constraints and improves battery life. - Abstract: Hybrid stand-alone renewable energy systems based on wind–solar resources are considered to be economically better and reliable than stand-alone systems with a single source. An isolated hybrid wind–solar system has been considered in this work, where the storage (battery bank) is necessary to supply the required reactive power for a wind-driven induction generator (IG) during the absence of power from a photovoltaic (PV) array. In such a scheme, to ensure zero Loss of Power Supply Probability (LPSP) and to improve battery bank life, a sizing procedure has been proposed with the incorporation of uncertainties in wind-speed and solar-irradiation level at the site of erection of the plant. Based on the proposed procedure, the size of hybrid power system components and storage capacity are determined. Storage capacity has been calculated for two different requirements. The first requirement of storage capacity is common to any hybrid scheme, which is; to supply both real and reactive power in the absence of wind and solar sources. The second requirement is to supply reactive power alone for the IG during the absence of photovoltaic power, which is unique to the hybrid scheme considered in this work. Storage capacity calculations for different conditions using the proposed approach, satisfies the constraints of maintaining zero LPSP and also improved cycle life of the battery bank

  19. NUMERICAL RESEARCH TECHNIQUES OF MAGNETIC FIELDS GENERATED BY INDUCTION CURRENTS IN A MASSIVE CONDUCTOR

    OpenAIRE

    Tchernykh A. G.

    2015-01-01

    We consider the technology of application of numerical methods in the educational process in physics on the example of a study of the magnetic field induced by induction currents in a cylindrical conductor in a quasi-stationary magnetic field. Here is given the numerical calculation of the real and imaginary parts of the Bessel functions of complex argument. The listing of the program of drawing the graphs of the radial dependence of the amplitude and phase shift of the inductive currents fie...

  20. Dynamic modeling and control of DFIG-based wind turbines under balanced network conditions

    DEFF Research Database (Denmark)

    Mehdipour, Cyrous; Hajizadeh, Amin; Mehdipour, Iman

    2016-01-01

    The performance of wind power station is researched by utilizing a detailed model which includes a wind turbine (WT), doubly fed induction generator (DFIG) and power electronic devices. In the initial stage, a comprehensive review and definition of each part of this system are presented...

  1. Control of Full-Scale Converter based Wind Power Plants for damping of low frequency system oscillations

    DEFF Research Database (Denmark)

    Adamczyk, Andrzej Grzegorz; Teodorescu, Remus; Rodriguez, Pedro

    2011-01-01

    Damping of low frequency power oscillations is one of essential aspects of maintaining power system stability. In literature can be found publications on damping capability of Doubly Fed Induction Generator based wind turbines. This paper extends discussion on Wind Power Plant damping capability...

  2. Operation of grid-connected DFIG under unbalanced grid voltage condition

    NARCIS (Netherlands)

    Zhou, Y.; Bauer, P.; Ferreira, J.A.; Pierik, J.

    2009-01-01

    Doubly fed induction generator (DFIG) still shares a large part in today's wind power market. It provides the benefits of variable speed operation cost-effectively, and can control its active and reactive power independently. Crowbar protection is often adopted to protect the rotor-side voltage

  3. Voltage Quality of Grid Connected Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede; Sun, Tao

    2004-01-01

    Grid connected wind turbines may cause quality problems, such as voltage variation and flicker. This paper discusses the voltage variation and flicker emission of grid connected wind turbines with doubly-fed induction generators. A method to compensate flicker by using a voltage source converter...

  4. Diode rectifier bridge-based structure for DFIG-based wind turbine

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2015-01-01

    This paper proposes a new structure for the doubly-fed induction generator (DFIG)-based wind turbine. The proposed structure consists of a DFIG controlled by a partial rated power converter in the rotor side, a three-phase diode rectifier bridge (DRB) connected to the stator, and a DC/AC full rated...

  5. High stability vector-based direct power control for DFIG-based wind turbine

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2015-01-01

    This paper proposes an improved vector-based direct power control (DPC) strategy for the doubly-fed induction generator (DFIG)-based wind energy conversion system. Based on the small signal model, the proposed DPC improves the stability of the DFIG, and avoids the DFIG operating in the marginal...

  6. Control of DFIG-WT under unbalanced grid voltage conditions

    DEFF Research Database (Denmark)

    Luna, Alvaro; Lina, Kleber; Corcoles, Felipe

    2009-01-01

    The voltage oriented control in the synchronous reference frame (VOC-SRF) have been extensively used for controlling wind turbines based on doubly fed induction generators (DFIG-WTs) through the rotor side converter of a back to back power processor. Although its performance is fast and accurate ...

  7. Enhanced control of DFIG wind turbine based on stator flux decay compensation

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Deng, Fujin; Chen, Zhe

    2016-01-01

    For the doubly-fed induction generator (DFIG)- based wind energy conversion system (WECS), the decaying flux and negative flux are the main reasons to cause the DFIG rotor overcurrent, during grid faults. The stator decaying flux characteristics versus the depth and instant of the stator voltage...

  8. Optimized design of resonant controller for stator current harmonic compensation in DFIG wind turbine systems

    DEFF Research Database (Denmark)

    Liu, Changjin; Chen, Wenjie; Blaabjerg, Frede

    2012-01-01

    This paper presents an analytical method to optimize the parameters of resonant controller which is used in a Doubly-Fed Induction Generator (DFIG). In the DFIG control system, the fundamental current loop is controlled by PI-controllers, and the stator harmonic current loop is controlled...

  9. Mitigation of Fatigue Loads Using Individual Pitch Control of Wind Turbines Based on FAST

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Cheng, Ming

    2011-01-01

    moments and fatigue. The loading transfer from rotational coordinate system to the fixed coordinate system of the wind turbine is analyzed. In order to make the simulation results more reliable, the wind turbine code FAST is applied to doubly fed induction generator (DFIG) based power system...

  10. Analysis and MPPT control of a wind-driven three-phase induction generator feeding single-phase utility grid

    Directory of Open Access Journals (Sweden)

    Krishnan Arthishri

    2017-05-01

    Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

  11. Performance analysis of a simple shunt and series compensated six-phase self-excited induction generator for stand-alone renewable energy generation

    International Nuclear Information System (INIS)

    Singh, G.K.; Kumar, A. Senthil; Saini, R.P.

    2011-01-01

    This paper describes a new generalized and efficient model for performance analysis of a six-phase self-excited induction generator (SPSEIG) with three capacitor excitation topologies; simple shunt, short shunt and long shunt. Mathematical model of SPSEIG is formulated using nodal admittance method based on graph theory. Attention is focused on the influence of the different capacitor connections on the generator overload and output power capabilities. The generator voltage with simple shunt excitation connection collapses when it is overloaded while with either the short shunt or long shunt excitation connection; generator is able to sustain the load at a lower operating voltage and larger load current. The matrix equation developed by nodal admittance method is solved by Genetic Algorithm (GA) technique to predetermine the steady-state performance of SPSEIG. The experimental and theoretical results are found to be in good agreement.

  12. Self-Excited Induction Generator Based Microgrid with Supercapacitor Energy Storage to Support the Start-up of Dynamic Loads

    Directory of Open Access Journals (Sweden)

    ION, C. P.

    2018-05-01

    Full Text Available A supercapacitor storage system (SCSS is used for improving the dynamic performances of a microgrid (MG fed by a self-excited induction generator (SEIG, in the case of the direct start-up of an induction motor (IM of comparable power. The primary control system contains a voltage source inverter (VSI with a dump load (DL, to which the SCSS is added. The control strategy for the SCSS consists of injecting power into the VSI DC-link when, because of the overload created by the IM, the DC voltage decreases under the acceptable limit. Thus, the overall performance of the SEIG-supplied MG is significantly improved. Simulations and experimental results accomplished on a laboratory-scale MG validate the effectiveness of the proposed control structure.

  13. Practicing induction:

    DEFF Research Database (Denmark)

    Sprogøe, Jonas; Rohde, Nicolas

    2009-01-01

    We claim that induction potentially triggers both individual and organizational learning and by drawing on practice-based theory we discuss how the interplay between individual and organization, what we call a generative dance, ignites both kinds of learning.......We claim that induction potentially triggers both individual and organizational learning and by drawing on practice-based theory we discuss how the interplay between individual and organization, what we call a generative dance, ignites both kinds of learning....

  14. Application of Boost Converter to Increase the Speed Range of Dual-stator Winding Induction Generator in Wind Power Systems

    DEFF Research Database (Denmark)

    Kavousi, Ayoub; Fathi, S. Hamid; Milimonfared, Jafar

    2018-01-01

    In this paper, a topology using a Dual-stator Winding Induction Generator (DWIG) and a boost converter is proposed for the variable speed wind power application. At low rotor speeds, the generator saturation limits the voltage of the DWIG. Using a boost converter, higher DC voltage can be produced...... while the DWIG operates at Maximum Power Point Tracking (MPPT) even at low speed and low voltage conditions. Semiconductor Excitation Controller (SEC) of the DWIG utilizes Control-Winding Voltage Oriented Control (CWVOC) method to adjust the voltage, considering V/f characteristics. For the proposed...... topology, the SEC capacity and the excitation capacitor is optimized by analyzing the SEC reactive current considering wind turbine power-speed curve, V/f strategy, and the generator parameters. The method shows that the per-unit capacity of the SEC can be limited to the inverse of DWIG magnetizing...

  15. Frequency Control in Autonomous Power Systems With High Wind Power Penetration

    DEFF Research Database (Denmark)

    Margaris, Ioannis D.; Papathanassiou, Stavros A.; Hatziargyriou, Nikos D.

    2012-01-01

    This paper presents an investigation on wind turbine (WT) contribution to the frequency control of noninterconnected island systems. The capability of WTs to participate in the primary frequency control and offer primary reserve is discussed. The investigation includes both transient frequency...... of Rhodes Island has been selected as a study case, which includes different types of conventional generation and the three basic WT types, based on Active-Stall Induction Generator (ASIG), Doubly Fed Induction Generator (DFIG), and Permanent Magnet Synchronous Generator (PMSG)....

  16. An improved excitation control technique of three-phase induction machine operating as dual winding generator for micro-wind domestic application

    International Nuclear Information System (INIS)

    Chatterjee, Arunava; Chatterjee, Debashis

    2015-01-01

    Highlights: • A three-phase induction machine working as single phase generator is studied. • The generator is assisted by an inverter and photovoltaic panel for excitation. • Proposed control involves operating the machine as balanced two-phase generator. • Torque pulsations associated with unbalanced phase currents are minimized. • The generator can be used for grid-isolated micro-wind power generation. - Abstract: Single-phase generation schemes are widely utilized for harnessing wind power in remote and grid secluded applications. This paper presents a novel control methodology for a three-phase induction machine working as a single-phase dual winding induction generator. Three-phase induction machines providing single-phase output with proper control strategy can be beneficial in grid secluded micro-wind energy conversion systems compared to single-phase induction generators. Three-phase induction machines operating in single-phase mode are mostly excited asymmetrically to provide single-phase power leading to unbalanced current flow in the stator windings causing heating and insulation breakdown. The asymmetrical excitation also initiates torque pulsations which results in additional stress and vibration at the machine shaft and bearings degrading the machine performance. The proposed control is chiefly aimed to minimize this unbalance. The variable excitation required for the proposed generator is provided through a single-phase inverter with photovoltaic panels. The suitability for such a generator along with its control is tested with appropriate simulations and experimental results. The induction generator with the proposed control strategy is expected to be useful in remote and grid isolated households as a standalone source of single-phase electrical power

  17. Development of a direct hydride generation nebulizer for the determination of selenium by inductively coupled plasma optical emission spectrometry

    International Nuclear Information System (INIS)

    Carrion, Nereida; Murillo, Miguel; Montiel, Edie; Diaz, Dorfe

    2003-01-01

    A study was conducted to evaluate the performance of a new direct hydride generation nebulizer system for determination of hydride forming elements by inductively coupled plasma optical emission spectroscopy. This system was designed and optimized to obtain the highest sensitivity. Several experimental designs were used for these purposes. To optimize the individual parameters of the system, and to study the interaction between these parameters for both direct hydride generation nebulizers, a central composite orthogonal design with eight factors was set up. Significant behavioral differences were observed in the two direct hydride generation nebulizers studied. Finally, a 70 μm gas orifice nebulizer exhibits a better detection limit than the 120 μm nebulizer. Generally, for determination of selenium, this new direct hydride generation nebulizer system exhibits a linear dynamic range and detection limit (3σb) of 3 orders of magnitude and 0.2 μg l -1 for selenium, respectively. This new hydride generator is much simpler system that conventional hydride generation systems, which does not need to be changed to work in normal mode with the inductively coupled plasma, since this system may be used for hydride forming elements and those that do not form them. It produces a rapid response with low memory effect. It reduces the interference level of Ni, Co and Cu to 600, 500 and 5 mg l -1 , respectively. The accuracy of the system was verified by the determination of selenium in several standard reference materials of ambient, food and clinical sample matrices. No statistically significant differences (95 confidence level) were obtained between our method and the reference values

  18. Pre- and post-natal exposure of children to EMF generated by domestic induction cookers

    Science.gov (United States)

    Kos, Bor; Valič, Blaž; Miklavčič, Damijan; Kotnik, Tadej; Gajšek, Peter

    2011-10-01

    Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard. The measurements were used to validate a numerical model consisting of three vertically displaced coaxial current loops at 35 kHz. The numerical model was then used to compute the electric field (E) and induced current (J) in 26 and 30 weeks pregnant women and 6 and 11 year old children. Both E and J were found to be below the basic restrictions of the 2010 low-frequency and 1998 ICNRIP guidelines. The maximum computed E fields in the whole body were 0.11 and 0.66 V m-1 in the 26 and 30 weeks pregnant women and 0.28 and 2.28 V m-1 in the 6 and 11 year old children (ICNIRP basic restriction 4.25 V m-1). The maximum computed J fields in the whole body were 46 and 42 mA m-2 in the 26 and 30 weeks pregnant women and 27 and 16 mA m-2 in the 6 and 11 year old children (ICNIRP basic restriction 70 mA m-2).

  19. Pre- and post-natal exposure of children to EMF generated by domestic induction cookers

    International Nuclear Information System (INIS)

    Kos, Bor; Miklavcic, Damijan; Kotnik, Tadej; Valic, Blaz; Gajsek, Peter

    2011-01-01

    Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard. The measurements were used to validate a numerical model consisting of three vertically displaced coaxial current loops at 35 kHz. The numerical model was then used to compute the electric field (E) and induced current (J) in 26 and 30 weeks pregnant women and 6 and 11 year old children. Both E and J were found to be below the basic restrictions of the 2010 low-frequency and 1998 ICNRIP guidelines. The maximum computed E fields in the whole body were 0.11 and 0.66 V m -1 in the 26 and 30 weeks pregnant women and 0.28 and 2.28 V m -1 in the 6 and 11 year old children (ICNIRP basic restriction 4.25 V m -1 ). The maximum computed J fields in the whole body were 46 and 42 mA m -2 in the 26 and 30 weeks pregnant women and 27 and 16 mA m -2 in the 6 and 11 year old children (ICNIRP basic restriction 70 mA m -2 ).

  20. Pre- and post-natal exposure of children to EMF generated by domestic induction cookers

    Energy Technology Data Exchange (ETDEWEB)

    Kos, Bor; Miklavcic, Damijan; Kotnik, Tadej [Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, SI-1000 Ljubljana (Slovenia); Valic, Blaz; Gajsek, Peter, E-mail: bor.kos@fe.uni-lj.si, E-mail: damijan.miklavcic@fe.uni-lj.si, E-mail: tadej.kotnik@fe.uni-lj.si, E-mail: blaz.valic@inis.si, E-mail: p.gajsek@inis.si [Institute of Non-Ionizing Radiation, Pohorskega Bataljona 215, SI-1000 Ljubljana (Slovenia)

    2011-10-07

    Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard. The measurements were used to validate a numerical model consisting of three vertically displaced coaxial current loops at 35 kHz. The numerical model was then used to compute the electric field (E) and induced current (J) in 26 and 30 weeks pregnant women and 6 and 11 year old children. Both E and J were found to be below the basic restrictions of the 2010 low-frequency and 1998 ICNRIP guidelines. The maximum computed E fields in the whole body were 0.11 and 0.66 V m{sup -1} in the 26 and 30 weeks pregnant women and 0.28 and 2.28 V m{sup -1} in the 6 and 11 year old children (ICNIRP basic restriction 4.25 V m{sup -1}). The maximum computed J fields in the whole body were 46 and 42 mA m{sup -2} in the 26 and 30 weeks pregnant women and 27 and 16 mA m{sup -2} in the 6 and 11 year old children (ICNIRP basic restriction 70 mA m{sup -2}).

  1. Self-Powered Random Number Generator Based on Coupled Triboelectric and Electrostatic Induction Effects at the Liquid-Dielectric Interface.

    Science.gov (United States)

    Yu, Aifang; Chen, Xiangyu; Cui, Haotian; Chen, Libo; Luo, Jianjun; Tang, Wei; Peng, Mingzeng; Zhang, Yang; Zhai, Junyi; Wang, Zhong Lin

    2016-12-27

    Modern cryptography increasingly employs random numbers generated from physical sources in lieu of conventional software-based pseudorandom numbers, primarily owing to the great demand of unpredictable, indecipherable cryptographic keys from true random numbers for information security. Thus, far, the sole demonstration of true random numbers has been generated through thermal noise and/or quantum effects, which suffers from expensive and complex equipment. In this paper, we demonstrate a method for self-powered creation of true random numbers by using triboelectric technology to collect random signals from nature. This random number generator based on coupled triboelectric and electrostatic induction effects at the liquid-dielectric interface includes an elaborately designed triboelectric generator (TENG) with an irregular grating structure, an electronic-optical device, and an optical-electronic device. The random characteristics of raindrops are harvested through TENG and consequently transformed and converted by electronic-optical device and an optical-electronic device with a nonlinear characteristic. The cooperation of the mechanical, electrical, and optical signals ensures that the generator possesses complex nonlinear input-output behavior and contributes to increased randomness. The random number sequences are deduced from final electrical signals received by an optical-electronic device using a familiar algorithm. These obtained random number sequences exhibit good statistical characteristics, unpredictability, and unrepeatability. Our study supplies a simple, practical, and effective method to generate true random numbers, which can be widely used in cryptographic protocols, digital signatures, authentication, identification, and other information security fields.

  2. Schemes of high-power pulsed generators with inductive storages on stepped lines

    International Nuclear Information System (INIS)

    Gordeev, V.S.; Bossamykin, V.S.

    1996-01-01

    Some multistage pulse generator designs based on homogeneous transmission lines of equal electrical length T 0 with stepwise impedance changes are described. The energy is initially stored as magnetic field by all the generator stages, while it is also stored by some of them as electrical energy. Upon triggering the switch connecting the high-voltage electrode of charged lines to the grounded generator frame, both the magnetic and electrical energies would concentrate completely at the generator output due to wave effects. Ideally, for any number of stages, the resistive load connected in parallel to the current opening switch is where a square-shaped voltage pulse of 2T 0 width would be generated, whose peak value can be considerably higher than the generator charging voltage. (author). 1 fig., 5 refs

  3. Schemes of high-power pulsed generators with inductive storages on stepped lines

    Energy Technology Data Exchange (ETDEWEB)

    Gordeev, V S; Bossamykin, V S [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    Some multistage pulse generator designs based on homogeneous transmission lines of equal electrical length T{sub 0} with stepwise impedance changes are described. The energy is initially stored as magnetic field by all the generator stages, while it is also stored by some of them as electrical energy. Upon triggering the switch connecting the high-voltage electrode of charged lines to the grounded generator frame, both the magnetic and electrical energies would concentrate completely at the generator output due to wave effects. Ideally, for any number of stages, the resistive load connected in parallel to the current opening switch is where a square-shaped voltage pulse of 2T{sub 0} width would be generated, whose peak value can be considerably higher than the generator charging voltage. (author). 1 fig., 5 refs.

  4. Sliding Mode Control of a Variable- Speed Wind Energy Conversion System Using a Squirrel Cage Induction Generator

    Directory of Open Access Journals (Sweden)

    Mohamed Zribi

    2017-05-01

    Full Text Available This paper deals with the control of a variable-speed wind energy conversion (WEC system using a squirrel cage induction generator (SCIG connected to the grid through a back-to-back three phase (AC-DC-AC power converter. The sliding mode control technique is used to control the WEC system. The objective of the controllers is to force the states of the system to track their desired states. One controller is used to regulate the generator speed and the flux so that maximum power is extracted from the wind. Another controller is used to control the grid side converter, which controls the DC bus voltage and the active and reactive powers injected into the grid. The performance of the controlled wind energy conversion system is verified through MATLAB simulations, which show that the controlled system performs well.

  5. The Neural Border: Induction, Specification and Maturation of the territory that generates Neural Crest cells.

    Science.gov (United States)

    Pla, Patrick; Monsoro-Burq, Anne H

    2018-05-28

    The neural crest is induced at the edge between the neural plate and the nonneural ectoderm, in an area called the neural (plate) border, during gastrulation and neurulation. In recent years, many studies have explored how this domain is patterned, and how the neural crest is induced within this territory, that also participates to the prospective dorsal neural tube, the dorsalmost nonneural ectoderm, as well as placode derivatives in the anterior area. This review highlights the tissue interactions, the cell-cell signaling and the molecular mechanisms involved in this dynamic spatiotemporal patterning, resulting in the induction of the premigratory neural crest. Collectively, these studies allow building a complex neural border and early neural crest gene regulatory network, mostly composed by transcriptional regulations but also, more recently, including novel signaling interactions. Copyright © 2018. Published by Elsevier Inc.

  6. Analysis of non-equilibrium phenomena in inductively coupled plasma generators

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.; Panesi, M., E-mail: mpanesi@illinois.edu [University of Illinois at Urbana-Champaign, Urbana, Illinois 61822 (United States); Lani, A. [Von Karman Institute for Fluid Dynamics, Rhode-Saint-Genèse (Belgium)

    2016-07-15

    This work addresses the modeling of non-equilibrium phenomena in inductively coupled plasma discharges. In the proposed computational model, the electromagnetic induction equation is solved together with the set of Navier-Stokes equations in order to compute the electromagnetic and flow fields, accounting for their mutual interaction. Semi-classical statistical thermodynamics is used to determine the plasma thermodynamic properties, while transport properties are obtained from kinetic principles, with the method of Chapman and Enskog. Particle ambipolar diffusive fluxes are found by solving the Stefan-Maxwell equations with a simple iterative method. Two physico-mathematical formulations are used to model the chemical reaction processes: (1) A Local Thermodynamics Equilibrium (LTE) formulation and (2) a thermo-chemical non-equilibrium (TCNEQ) formulation. In the TCNEQ model, thermal non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules is accounted for. The electronic states of the chemical species are assumed in equilibrium with the vibrational temperature, whereas the rotational energy mode is assumed to be equilibrated with translation. Three different physical models are used to account for the coupling of chemistry and energy transfer processes. Numerical simulations obtained with the LTE and TCNEQ formulations are used to characterize the extent of non-equilibrium of the flow inside the Plasmatron facility at the von Karman Institute. Each model was tested using different kinetic mechanisms to assess the sensitivity of the results to variations in the reaction parameters. A comparison of temperatures and composition profiles at the outlet of the torch demonstrates that the flow is in non-equilibrium for operating conditions characterized by pressures below 30 000 Pa, frequency 0.37 MHz, input power 80 kW, and mass flow 8 g/s.

  7. Pulsed, Inductively Generated, Streaming Plasma Ion Source for Heavy Ion Fusion Linacs

    International Nuclear Information System (INIS)

    Steven C. Glidden; Howard D Sanders; John B. Greenly; Daniel L. Dongwoo

    2006-01-01

    This report describes a compact, high current density, pulsed ion source, based on electrodeless, inductively driven gas breakdown, developed to meet the requirements on normalized emittance, current density, uniformity and pulse duration for an ion injector in a heavy-ion fusion driver. The plasma source produces >10 (micro)s pulse of Argon plasma with ion current densities >100 mA/cm2 at 30 cm from the source and with strongly axially directed ion energy of about 80 eV, and sub-eV transverse temperature. The source has good reproducibility and spatial uniformity. Control of the current density during the pulse has been demonstrated with a novel modulator coil method which allows attenuation of the ion current density without significantly affecting the beam quality. This project was carried out in two phases. Phase 1 used source configurations adapted from light ion sources to demonstrate the feasibility of the concept. In Phase 2 the performance of the source was enhanced and quantified in greater detail, a modulator for controlling the pulse shape was developed, and experiments were conducted with the ions accelerated to >40 kV

  8. New circuits high-voltage pulse generators with inductive-capacitive energy storage

    International Nuclear Information System (INIS)

    Gordeev, V.S.; Myskov, G.A.

    2001-01-01

    The paper describes new electric circuits of multi-cascade generators based on stepped lines. The distinction of the presented circuits consists in initial storage of energy in electric and magnetic fields simultaneously. The circuit of each generator,relations of impedances,values of initial current and charge voltages are selected in such a manner that the whole of initially stored energy is concentrated at the generator output as a result of transient wave processes. In ideal case the energy is transferred with 100% efficiency to the resistive load where a rectangular voltage pulse is formed, whose duration is equals to the double electrical length of the individual cascade. At the same time there is realized a several time increase of output voltage as compared to the charge voltage of the generator. The use of the circuits proposed makes it possible to ensure a several time increase (as compared to the selection of the number of cascades) of the generator energy storage, pulse current and output electric power

  9. Study on transient stability of wind turbine with induction generator based on variable pitch control strategy

    DEFF Research Database (Denmark)

    Zhao, B.; Li, H.; Han, L.

    2011-01-01

    In order to enhance and improve the transient stability of a grid-connected wind turbine generator system under the power grid fault, based on typical pitch control strategy of wind turbine, considering the wind turbine system oscillation caused by the drive-train shaft flexibility, Based on Matl...

  10. Induction of oxygen free radical generation in human monocytes by lipoprotein(a)

    DEFF Research Database (Denmark)

    Riis Hansen, P; Kharazmi, A; Jauhiainen, M

    1994-01-01

    The mechanism behind the association of elevated plasma lipoprotein(a) [Lp(a)] levels with atherosclerotic disease is unknown. In the present study, Lp(a) induced generation of oxygen free radicals by monocytes from selected healthy individuals in vitro. This observation may provide a link between...

  11. Transient analysis of a grid connected wind driven induction generator using a real-time simulation platform

    Energy Technology Data Exchange (ETDEWEB)

    Ouhrouche, Mohand [Department of Applied Sciences, University of Quebec at Chicoutimi, Quebec, G7H2B1 (Canada)

    2009-03-15

    Due to its simple construction, ruggedness and low cost, the induction generator driven by a wind turbine and feeding power to the grid appears to be an attractive solution to the problem of growing energy demand in the context of environmental issues. This paper investigates the integration of such a system into the main utility using RT-Lab trademark (Trademark of Opal-RT Technologies) software package running on a simple off-the-shelf PC. This real-time simulation platform is now adopted by many high-tech industries as a real-time laboratory package for rapid control prototyping and for Hardware-in-the-Loop applications. Real-time digital simulation results obtained during contingencies, such as islanding and unbalanced faults are presented and analysed. (author)

  12. A technical note about Phidel: A new software for evaluating magnetic induction field generated by power lines

    International Nuclear Information System (INIS)

    Comelli, M.; Benes, M.; Bampo, A.; Villalta, R.

    2007-01-01

    The Regional Environment Protection Agency of Friuli Venezia Giulia (ARPA FVG, Italy) has performed an analysis on existing software designed to calculate magnetic induction field generated by power lines. As far as the agency's requirements are concerned the tested programs display some difficulties in the immediate processing of electrical and geometrical data supplied by plant owners, and in certain cases turn out to be inadequate in representing complex configurations of power lines. Phidel, an innovative software, tackles and works out all the above-mentioned problems. Therefore, the obtained results, when compared with those of other programs, are the closest to experimental measurements. The output data can be employed both in the GIS and Excel environments, allowing the immediate overlaying of digital cartography and the determining of the 3 and 10 μT bands, in compliance with the Italian Decree of the President of the Council of Ministers of 8 July 2003. (authors)

  13. Semi-automatic determination of tin in marine materials by continuous flow hydride generation inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Feng Yonglai; Narasaki, Hisataki; Chen Hongyuan; Tian Liching

    1997-01-01

    A semi-automated continuous flow hydride generation system with inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of tin in marine materials. The effects of acids (H 2 SO 4 and HCl) were studied. The analytical parameters were thoroughly investigated. Under optimized conditions, the detection limit is 0.4 ng/ml. Interferences from transition elements were investigated and seven masking reagents were tested. L-cysteine hydrochloride monohydrate (1%) was used to mask the interferences from foreign ions. Finally, the accuracy, checked with a marine standard reference material obtained from the National Research Council (NRC), was within the certified value. (orig.). With 6 figs., 4 tabs

  14. Powerful accelerators for bremsstrahlung and electron beams generation on the basis of inductive energy-storage elements

    Energy Technology Data Exchange (ETDEWEB)

    Diyankov, V S; Kovalev, V P; Kormilitsin, A I; Lavrentev, B N [All-Russian Research Institute of Technical Physics, Snezhinsk (Russian Federation)

    1997-12-31

    The report summarizes RFNC-VNIITF activities from 1963 till 1995, devoted to the development of pulsed electron accelerators on the basis of inductive energy storage with electroexplosive wires. These accelerators are called IGUR. The activities resulted in the development of a series of generators of powerful radiation being cheap and easy in manufacturing and servicing. The accelerators achieved the following maximum parameters: diode voltage up to 6 MV, diode current up to 80 kA, current of the extracted electron beam 30 kA, density of the extracted electron beam energy 500 J/cm{sup 2}, bremsstrahlung dose 250000 Rads, and bremsstrahlung dose rate 10{sup 13} Rads/sec. (author). 3 tabs., 5 figs., 7 refs.

  15. Powerful accelerators for bremsstrahlung and electron beams generation on the basis of inductive energy-storage elements

    International Nuclear Information System (INIS)

    Diyankov, V.S.; Kovalev, V.P.; Kormilitsin, A.I.; Lavrentev, B.N.

    1996-01-01

    The report summarizes RFNC-VNIITF activities from 1963 till 1995, devoted to the development of pulsed electron accelerators on the basis of inductive energy storage with electroexplosive wires. These accelerators are called IGUR. The activities resulted in the development of a series of generators of powerful radiation being cheap and easy in manufacturing and servicing. The accelerators achieved the following maximum parameters: diode voltage up to 6 MV, diode current up to 80 kA, current of the extracted electron beam 30 kA, density of the extracted electron beam energy 500 J/cm 2 , bremsstrahlung dose 250000 Rads, and bremsstrahlung dose rate 10 13 Rads/sec. (author). 3 tabs., 5 figs., 7 refs

  16. UV-generated free radicals (FR) in skin: Their prevention by sunscreens and their induction by self-tanning agents

    Science.gov (United States)

    Jung, K.; Seifert, M.; Herrling, Th.; Fuchs, J.

    2008-05-01

    In the past few years, the cellular effects of ultraviolet (UV) irradiation induced in skin have become increasingly recognized. Indeed, it is now well known that UV irradiation induces structural and cellular changes in all the compartments of skin tissue. The generation of reactive oxygen species (ROS) is the first and immediate consequence of UV exposure and therefore the quantitative determination of free radical reactions in the skin during UV radiation is of primary importance for the understanding of dermatological photodamage. The RSF method (radical sun protection factor) herein presented, based on electron spin resonance spectroscopy (ESR), enables the measurement of free radical reactions in skin biopsies directly during UV radiation. The amount of free radicals varies with UV doses and can be standardized by varying UV irradiance or exposure time. The RSF method allows the determination of the protective effect of UV filters and sunscreens as well as the radical induction capacity of self-tanning agents as dihydroxyacetone (DHA). The reaction of the reducing sugars used in self-tanning products and amino acids in the skin layer (Maillard reaction) leads to the formation of Amadori products that generate free radicals during UV irradiation. Using the RSF method three different self-tanning agents were analyzed and it was found, that in DHA-treated skin more than 180% additional radicals were generated during sun exposure with respect to untreated skin. For this reason the exposure duration in the sun must be shortened when self-tanners are used and photoaging processes are accelerated.

  17. Comparison of 2D and 3D neural induction methods for the generation of neural progenitor cells from human induced pluripotent stem cells.

    Science.gov (United States)

    Chandrasekaran, Abinaya; Avci, Hasan X; Ochalek, Anna; Rösingh, Lone N; Molnár, Kinga; László, Lajos; Bellák, Tamás; Téglási, Annamária; Pesti, Krisztina; Mike, Arpad; Phanthong, Phetcharat; Bíró, Orsolya; Hall, Vanessa; Kitiyanant, Narisorn; Krause, Karl-Heinz; Kobolák, Julianna; Dinnyés, András

    2017-12-01

    Neural progenitor cells (NPCs) from human induced pluripotent stem cells (hiPSCs) are frequently induced using 3D culture methodologies however, it is unknown whether spheroid-based (3D) neural induction is actually superior to monolayer (2D) neural induction. Our aim was to compare the efficiency of 2D induction with 3D induction method in their ability to generate NPCs, and subsequently neurons and astrocytes. Neural differentiation was analysed at the protein level qualitatively by immunocytochemistry and quantitatively by flow cytometry for NPC (SOX1, PAX6, NESTIN), neuronal (MAP2, TUBB3), cortical layer (TBR1, CUX1) and glial markers (SOX9, GFAP, AQP4). Electron microscopy demonstrated that both methods resulted in morphologically similar neural rosettes. However, quantification of NPCs derived from 3D neural induction exhibited an increase in the number of PAX6/NESTIN double positive cells and the derived neurons exhibited longer neurites. In contrast, 2D neural induction resulted in more SOX1 positive cells. While 2D monolayer induction resulted in slightly less mature neurons, at an early stage of differentiation, the patch clamp analysis failed to reveal any significant differences between the electrophysiological properties between the two induction methods. In conclusion, 3D neural induction increases the yield of PAX6 + /NESTIN + cells and gives rise to neurons with longer neurites, which might be an advantage for the production of forebrain cortical neurons, highlighting the potential of 3D neural induction, independent of iPSCs' genetic background. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Infrared signal generation from AC induction field heating of graphite foam

    Science.gov (United States)

    Klett, James W.; Rios, Orlando

    2018-02-27

    A magneto-energy apparatus includes an electromagnetic field source for generating a time-varying electromagnetic field. A graphite foam conductor is disposed within the electromagnetic field. The graphite foam when exposed to the time-varying electromagnetic field conducts an induced electric current, the electric current heating the graphite foam to produce light. An energy conversion device utilizes light energy from the heated graphite foam to perform a light energy consuming function. A device for producing light and a method of converting energy are also disclosed.

  19. An electrical dynamo that is a new technology over the generation of electricity by induction

    International Nuclear Information System (INIS)

    Hickox, B.

    1991-01-01

    This invention describes a different device for generating a type alternating electrical power. In the paper an electrical generator is described with one or more nonconductive cylinders mounted for rotation about an axis and containing at lest four pairs of permanent magnets, longitudinally spaced within the cylinder and angularly offset from each other in a helical array. Each of the magnets in each pair is radially disposed in the cylinder opposite the other and separated from the other at the cylinder axis with like poles facing each other. An electrical secondary is provided within the magnetic field of the magnets in the cylinder. A ring magnetic is oriented with an axis parallel to the cylinder axis an is relatively moveable there along. The magnetic fields acting between the ring magnet and the magnets in the cylinder rotates the cylinder to induce electrical current in the generatory secondary. A working model of this device has been constructed and tested. Other researchers are currently building and testing other similar units and various embodiments and applications of this device. This device warrants further testing and closer study

  20. Direct Drive Synchronous Machine Models for Stability Assessment of Wind Farms

    Energy Technology Data Exchange (ETDEWEB)

    Poeller, Markus; Achilles, Sebastian [DIgSILENT GmbH, Gomaringen (Germany)

    2003-11-01

    The increasing size of wind farms requires power system stability analysis including dynamic wind generator models. For turbines above 1MW doubly-fed induction machines are the most widely used concept. However, especially in Germany, direct-drive wind generators based on converter-driven synchronous generator concepts have reached considerable market penetration. This paper presents converter driven synchronous generator models of various order that can be used for simulating transients and dynamics in a very wide time range.

  1. Optoelectronic properties of Black-Silicon generated through inductively coupled plasma (ICP) processing for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Jens, E-mail: J.Hirsch@emw.hs-anhalt.de [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany); Gaudig, Maria; Bernhard, Norbert [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Lausch, Dominik [Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany)

    2016-06-30

    Highlights: • Fabrication of black silicon through inductively coupled plasma (ICP) processing. • Suppressed formation a self-bias and therefore a reduced ion bombardment of the silicon sample. • Reduction of the average hemispherical reflection between 300 and 1120 nm up to 8% within 5 min ICP process time. • Reflection is almost independent of the angle of incidence up to 60°. • 2.5 ms effective lifetime at 10{sup 15} cm{sup −3} MCD after ALD Al{sub 2}O{sub 3} surface passivation. - Abstract: The optoelectronic properties of maskless inductively coupled plasma (ICP) generated black silicon through SF{sub 6} and O{sub 2} are analyzed by using reflection measurements, scanning electron microscopy (SEM) and quasi steady state photoconductivity (QSSPC). The results are discussed and compared to capacitively coupled plasma (CCP) and industrial standard wet chemical textures. The ICP process forms parabolic like surface structures in a scale of 500 nm. This surface structure reduces the average hemispherical reflection between 300 and 1120 nm up to 8%. Additionally, the ICP texture shows a weak increase of the hemispherical reflection under tilted angles of incidence up to 60°. Furthermore, we report that the ICP process is independent of the crystal orientation and the surface roughness. This allows the texturing of monocrystalline, multicrystalline and kerf-less wafers using the same parameter set. The ICP generation of black silicon does not apply a self-bias on the silicon sample. Therefore, the silicon sample is exposed to a reduced ion bombardment, which reduces the plasma induced surface damage. This leads to an enhancement of the effective charge carrier lifetime up to 2.5 ms at 10{sup 15} cm{sup −3} minority carrier density (MCD) after an atomic layer deposition (ALD) with Al{sub 2}O{sub 3}. Since excellent etch results were obtained already after 4 min process time, we conclude that the ICP generation of black silicon is a promising technique

  2. Generation of ion-acoustic waves in an inductively coupled, low-pressure discharge lamp

    International Nuclear Information System (INIS)

    Camparo, J. C.; Klimcak, C. M.

    2006-01-01

    For a number of years it has been known that the alkali rf-discharge lamps used in atomic clocks can exhibit large amplitude intensity oscillations. These oscillations arise from ion-acoustic plasma waves and have typically been associated with erratic clock behavior. Though large amplitude ion-acoustic plasma waves are clearly deleterious for atomic clock operation, it does not follow that small amplitude oscillations have no utility. Here, we demonstrate two easily implemented methods for generating small amplitude ion-acoustic plasma waves in alkali rf-discharge lamps. Furthermore, we demonstrate that the frequency of these waves is proportional to the square root of the rf power driving the lamp and therefore that their examination can provide an easily accessible parameter for monitoring and controlling the lamp's plasma conditions. This has important consequences for precise timekeeping, since the atomic ground-state hyperfine transition, which is the heart of the atomic clock signal, can be significantly perturbed by changes in the lamp's output via the ac-Stark shift

  3. Generation of a vascularized organoid using skeletal muscle as the inductive source.

    LENUS (Irish Health Repository)

    Messina, Aurora

    2005-09-01

    The technology required for creating an in vivo microenvironment and a neovasculature that can grow with and service new tissue is lacking, precluding the possibility of engineering complex three-dimensional organs. We have shown that when an arterio-venous (AV) loop is constructed in vivo in the rat groin, and placed inside a semisealed chamber, an extensive functional vasculature is generated. To test whether this unusually angiogenic environment supports the survival and growth of implanted tissue or cells, we inserted various preparations of rat and human skeletal muscle. We show that after 6 weeks incubation of muscle tissue, the chamber filled with predominantly well-vascularized recipient-derived adipose tissue, but some new donor-derived skeletal muscle and connective tissue were also evident. When primary cultured myoblasts were inserted into the chamber with the AV loop, they converted to mature striated muscle fibers. Furthermore, we identify novel adipogenesis-inducing properties of skeletal muscle. This represents the first report of a specific three-dimensional tissue grown on its own vascular supply.

  4. Tin Content Determination in Canned Fruits and Vegetables by Hydride Generation Inductively Coupled Plasma Optical Emission Spectrometry

    Directory of Open Access Journals (Sweden)

    Sanda Rončević

    2012-01-01

    Full Text Available Tin content in samples of canned fruits and vegetables was determined by hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-OES, and it was compared with results obtained by standard method of flame atomic absorption spectrometry (AAS. Selected tin emission lines intensity was measured in prepared samples after addition of tartaric acid and followed by hydride generation with sodium borohydride solution. The most favorable line at 189.991 nm showed the best detection limit (1.9 μg L−1 and limit of quantification (6.4 μg kg−1. Good linearity and sensitivity were established from time resolved analysis and calibration tests. Analytical accuracy of 98–102% was obtained by recovery study of spiked samples. Method of standard addition was applied for tin determination in samples from fully protected tinplate. Tin presence at low-concentration range was successfully determined. It was shown that tenth times less concentrations of Sn were present in protected cans than in nonprotected or partially protected tinplate.

  5. Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

    Directory of Open Access Journals (Sweden)

    Takwa Sellami

    2017-10-01

    Full Text Available The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO-based Fault Tolerant Control (FTC scheme for Induction Generator (IG-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT method and Indirect Rotor Flux Oriented Control (IRFOC method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality.

  6. Integration of offshore wind farms into the local distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Youssef, R.D. [and others

    2003-07-01

    This report summarises the results of a study developing static and dynamic models for a doubly-fed induction generator and the integration of the models into the commercially available and widely used power system analysis computer programme IPSA. Details are given of connection studies involving fixed speed, variable speed and double-fed induction machines; the development of optimal power flow and use of the Optimal Power Flow (OPF) tool; and voltage control studies. The system and offshore connection, connection studies and policies, technical problems, stability connection studies for wind farms with synchronous generators and transient stability connection studies for fixed speed and doubly-fed induction generators are discussed along with the integration of OPF into IPSA.

  7. In-duct countermeasures for reducing fire-generated-smoke-aerosol exposure to HEPA filters

    International Nuclear Information System (INIS)

    Alvares, N.J.; Beason, D.G.; Ford, H.W.

    1978-01-01

    An experimental program was conducted to assess the endurance and lifetime of HEPA filters exposed to fire-generated aerosols, and to reduce the aerosol exposure by installing engineering countermeasures in the duct between the fire source and HEPA filters. Large cribs of wood and other potential fuels of interest were ''forcefully burned'' in a partially ventilated enclosure. In a ''forceful burn'' the crib of fuel is continuously exposed to an energetic premixed methane flame during the entire experimental period. This tactic serves two purposes: it optimizes the production of smoke rich in unburned pyrolyzates which provides severe exposure to the filters, and it facilitates the ignition and enhances the combustion of cribs formed with synthetic polymers. The experiments were conducted in an enclosure specifically designed and instrumented for fire tests. The test cell has a volume of 100 m 3 and includes instrumentation to measure the internal temperature distribution, pressure, thermal radiation field, flow fields, gas concentration, particulate size distribution and mass, fuel weight loss, inlet and exit air velocities, and smoke optical density. The countermeasure techniques include the use of passively operated sprinkler systems in the fire test cell, of fine and dense water scrubbing sprays, and of rolling prefiltration systems in the exit duct of the fire test cell. Of the countermeasures surveyed, the rolling prefilter system showed the most promise. This paper concentrates on the effect of control variables; i.e., enclosure air supply, fuel composition and crib porosity on the combustion response; i.e., crib burning rate, enclosure temperature rise, oxygen consumption, and CO, CO 2 and total hydrocarbon production. A discussion of the attempts to rationalize smoke aerosol properties will be included along with results from the effect of countermeasure application on HEPA filter lifetimes

  8. 0D modelling and efficiency analysis of three power amplification schemes for inductive storage generators in the μs scale

    International Nuclear Information System (INIS)

    Huet, D.; Lassalle, F.; Chuvatin, A.S.

    2005-01-01

    Extensive studies were conducted to sharpen current pulse on IES (Inductive Energy Storage) drivers using the plasma opening switch scheme. Due to the emergence of new power amplification concepts, new opportunities appear for improving IES generators operation. In order to evaluate and compare the performances of these schemes this paper proposes a system analysis based on a 0D modelling [ru

  9. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    Science.gov (United States)

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Second-order Sliding Mode Control of DFIG Based Variable Speed Wind Turbine for Maximum Power Point Tracking

    Institute of Scientific and Technical Information of China (English)

    Xiangjie Liu; Chengcheng Wang; Yaozhen Han

    2017-01-01

    This paper proposes a super-twisting second order sliding mode control scheme to maximize the wind energy capture of a doubly fed induction generator based variable speed wind turbine (VSWT) system, and minimize the reactive power simultaneously. Two second order sliding mode controllers are designed to achieve the control objectives, reduce mechanical stress and improve control accuracy. By regulating the generator rotor voltage, one controller makes the wind turbine rotor speed track the optimal speed, which can maximize power generation. The other maintains the rotor current at rated value to minimize the reactive power. A quadratic form Lyapunov function is adopted to determine the range of controller parameters and guarantee the finite time stability. Simulation results on a 1.5 MW doubly fed induction generator (DFIG)-based variable speed wind turbine demonstrate the validity of the proposed control strategy.

  11. Influence of Crowbar and Chopper Protection on DFIG during Low Voltage Ride Through

    Directory of Open Access Journals (Sweden)

    Rita M. Monteiro Pereira

    2018-04-01

    Full Text Available The energy sector is evolving rapidly, namely due to the increasing importance of renewable energy sources. The connection of large amounts of wind power generation poses new challenges for the dynamic voltage stability analysis of an electric power system, which has to be studied. In this paper, the traditional Doubly-Fed Induction Generator model is employed. Based on this model, a crowbar and chopper circuit is set up to protect the turbine during the short-circuit period. The EUROSTAG software package was used for the simulation studies of the system, and numerical results were obtained. Conclusions are drawn that provide a better understanding of the influence of crowbar and chopper protection on Doubly-Fed Induction Generators (DFIG, during low voltage ride through, in a system with wind power generation.

  12. NSGA-II based optimal control scheme of wind thermal power system for improvement of frequency regulation characteristics

    Directory of Open Access Journals (Sweden)

    S. Chaine

    2015-09-01

    Full Text Available This work presents a methodology to optimize the controller parameters of doubly fed induction generator modeled for frequency regulation in interconnected two-area wind power integrated thermal power system. The gains of integral controller of automatic generation control loop and the proportional and derivative controllers of doubly fed induction generator inertial control loop are optimized in a coordinated manner by employing the multi-objective non-dominated sorting genetic algorithm-II. To reduce the numbers of optimization parameters, a sensitivity analysis is done to determine that the above mentioned three controller parameters are the most sensitive among the rest others. Non-dominated sorting genetic algorithm-II has depicted better efficiency of optimization compared to the linear programming, genetic algorithm, particle swarm optimization, and cuckoo search algorithm. The performance of the designed optimal controller exhibits robust performance even with the variation in penetration levels of wind energy, disturbances, parameter and operating conditions in the system.

  13. 异步发电机

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Comparison of fixed speed and doubly-fed induction wind turbines during power system disturbances; Comparison of the weak grid dynamic behavior by the WECS connection of different power; Investigation of faults in autonomous wind-diesel hybrid energy system by simulation; Investigation of the three phase short circuit in a weak power system including WECS; Mathematical Model of an Asynchronous Generator Taking the Iron Losses into Account; Mathematical modeling of an asynchronous switched generator;

  14. Wind power stabilising control : Demonstration on the Nordic grid

    OpenAIRE

    Elkington, Katherine

    2012-01-01

    When unconventional types of generators such as doubly fed induction generators (DFIGs) are used in a power system, the system behaves differently under abnormal dynamic events. For example, DFIGs cause different modes of oscillation in the power system, and respond differently to changes in voltage. In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods of optimally damping the oscillations. Large power oscillation...

  15. Sizing modelling and simulation of PV generation system feeding a 6 MW induction motor dedicated to pumping applications

    Directory of Open Access Journals (Sweden)

    Samir HADJERI

    2017-06-01

    Full Text Available This paper proposes an autonomous photovoltaic (PV pumping system for rural/remote applications especially in the large desert in northern Africa where the sun radiation is abundant. Since PV generators exhibit nonlinear I-V characteristics and their maximum power point varies with solar radiation. For this reason, the MPPT controller is used to optimize the solar energy conversion by guaranteeing fast maximum power point tracking (MPPT. This feature has an essential role in dynamic response and efficiency of the photovoltaic system, thus it maximizes the amount of extracted natural gas to be conveyed to another site for an ulterior utilization. Here a robust maximum power point tracker (MPPT using incremental conductance algorithm is applied to the duty cycle value of the DC-DC converter which acts directly on the drive speed. A DC/DC boost is used to enhance voltage up to the favourite level and the SVPWM inverter connects it to a powerful induction motor for a pumping of natural gas application, these systems are at the heart of many industrial sectors such as the oil industry, the production of thermal and nuclear energy etc. An understanding of how these systems operate is essential to increase their performance and reduce their operating costs. Furthermore, three phase voltage-fed PWM inverters are recently showing growing popularity for multi-megawatt industrial drive applications, the main purpose of these topologies is to provide a three-phase voltage source, where the amplitude, phase, and frequency of the voltages should always be controllable. The model of a three-phase voltage source inverter is modelled and discussed based on space vector modulation theory. Simulation results are obtained using MATLAB/Simulink environment for effectiveness of the proposed system.

  16. Fundamental-frequency and load-varying thermal cycles effects on lifetime estimation of DFIG power converter

    DEFF Research Database (Denmark)

    Zhang, G.; Zhou, D.; Yang, J.

    2017-01-01

    In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been ...... adopted to handle the fundamental-frequency thermal cycles and load-varying thermal cycles. Their effects on lifetime estimation of the power device in the Back-to-Back (BTB) power converter are evaluated.......In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been...

  17. Discontinuous interleaving of parallel inverters for efficiency improvement

    DEFF Research Database (Denmark)

    Rannestad, Bjørn; Munk-Nielsen, Stig; Gadgaard, Kristian

    2017-01-01

    Interleaved switching of parallel inverters has previously been proposed for efficiency/size improvements of grid connected three-phase inverters. This paper proposes a novel interleaving method which practically eliminates insulated gate bipolar transistor (IGBT) turn-on losses and drastically...... overall power module losses are reduced. The modulation strategy is suited for converters with doubly fed induction generators (DFIG) for wind turbines, but are not limited hereto. Improvement of switching performance are measured and operational efficiency improvements are calculated and verified...

  18. Improved FRT Control Scheme for DFIG Wind Turbine Connected to a Weak Grid

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Chen, Zhe; Iov, Florin

    2013-01-01

    This paper presents an improved coordinated fault ridethrough (FRT) control strategy for a doubly fed induction generator (DFIG) based wind turbine, (WT), in a weak grid. A technique for grid synchronization against voltage excursions, i.e., a Dual Second Order Generalized Integrator – Frequency ...... controllers to counteract rotor as well as stator currents and regulate the rotor speed. Simulation results which assure the effectiveness of the proposed control scheme is presented....

  19. Use of oxidative and reducing vapor generation for reducing the detection limits of iodine in biological samples by inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Vtorushina, Eh.A.; Saprykin, A.I.; Knapp, G.

    2009-01-01

    Procedures of microwave combustion in an oxygen flow and microwave acid decomposition of biological samples were optimized for the subsequent determination of iodine. A new method was proposed for the generation of molecular iodine from periodate iona using hydrogen peroxide as a reductant. Procedures were developed for determining iodine in biological samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) using oxidative and reducing vapor generation; these allowed the detection limit for iodine to be lowered by 3-4 orders of magnitude. The developed procedures were used to analyze certified reference materials of milk (Skim Milk Powder BCR 150) and seaweed (Sea Lettuce BCR 279) and a Supradyn vitamin complex

  20. A high-voltage equipment (high voltage supply, high voltage pulse generators, resonant charging inductance, synchro-instruments for gyrotron frequency measurements) for plasma applications

    International Nuclear Information System (INIS)

    Spassov, Velin

    1996-01-01

    This document reports my activities as visitor-professor at the Gyrotron Project - INPE Plasma Laboratory. The main objective of my activities was designing, construction and testing a suitable high-voltage pulse generator for plasma applications, and efforts were concentrated on the following points: Design of high-voltage resonant power supply with tunable output (0 - 50 kV) for line-type high voltage pulse generator; design of line-type pulse generator (4 microseconds pulse duration, 0 - 25 kV tunable voltage) for non linear loads such as a gyrotron and P III reactor; design of resonant charging inductance for resonant line-type pulse generator, and design of high resolution synchro instrument for gyrotron frequency measurement. (author)

  1. Ultra-trace determination of iodine in sediments and biological material using UV photochemical generation-inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Grinberg, Patricia [Institute for National Measurements Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6 (Canada)], E-mail: patricia.grinberg@nrc.ca; Sturgeon, Ralph E. [Institute for National Measurements Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6 (Canada)

    2009-03-15

    Several sample preparation techniques have been evaluated for the determination of iodine using UV-photochemical generation-quadrupole inductively coupled plasma mass spectrometry. Thermal decomposition of samples at 1000 {sup o}C followed by capture of the liberated iodine in dilute acetic acid permitted subsequent UV-photochemical generation of a volatile iodine species that serves to enhance sensitivity 25-fold over conventional solution nebulization, delivering reagent blank detection limits of 8.75 pg g{sup -1127}I and 0.075 pg g{sup -1129}I for solid samples (400 mg test mass). The methodology was validated through determination of total iodine in several Standard Reference Materials, including NIST 1572 Citrus leaves, NIST 1549 Non-fat milk powder, NIST 1566a Oyster tissue and NIST 2709 San Joaquin Soil. Liberation of iodine from samples and its collection as well as photochemical generation were quantitative, permitting calibration to be achieved using standards prepared in dilute acetic acid.

  2. Integration of permanent magnet synchronous generator wind turbines into power grid

    Science.gov (United States)

    Abedini, Asghar

    , integrating energy storage systems with wind farms has attracted a lot of attention. These two subjects are addressed in this dissertation in detail. Permanent Magnet Synchronous Generators (PMSG) are used in variable speed wind turbines. In this thesis, the dynamic of the PMSG is investigated and a power electronic converter is designed to integrate the wind turbine to the grid. The risks of PMSG wind turbines such as low voltage ride through and short circuits, are assessed and the methods of mitigating the risks are discussed. In the second section of the thesis, various methods of smoothing wind turbine output power are explained and compared. Two novel methods of output power smoothing are analyzed: Rotor inertia and Super capacitors. The advantages and disadvantages of each method are explained and the dynamic model of each method is developed. The performance of the system is evaluated by simulating the wind turbine system in each method. The concepts of the methods of smoothing wind power can be implemented in other types of wind turbines such as Doubly Fed Induction Generator (DFIG) wind turbines.

  3. Interval type-2 fuzzy gain-adaptive controller of a Doubly Fed ...

    African Journals Online (AJOL)

    ... Interval Type-2 Fuzzy Gain Adaptive IP (IT2FGAIP) controller and a conventional IP controller ... and an adaptive IP controller is proposed for the speed control of DFIM in the presence of ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  4. High Efficiency Power Converter for a Doubly-fed SOEC/SOFC System

    DEFF Research Database (Denmark)

    Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe

    2016-01-01

    Regenerative fuel cells (RFC) have become an attractive technology for energy storage systems due to their high energy density and lower end-of-life disposal concerns. However, high efficiency design of power conditioning unit (PCU) for RFC becomes challenging due to their asymmetrical currentpow...... operating range of the RFC as well as the utilization of the same control strategy design for the two RFC operating modes....

  5. interval type-2 fuzzy gain-adaptive controller of a doubly fed

    African Journals Online (AJOL)

    Loukal K and Benalia L

    2016-05-01

    May 1, 2016 ... machine a converter PWM (Pulse Width Modulation) between the machine ... operations on fuzzy sets increases with the increasing type of the fuzzy set. ...... Several simulations have been run using the Matlab and Simulink® ...

  6. SYSTEM OPTIMIZATION FOR THE AUTOMATIC SIMULTANEOUS DETERMINATION OF ARSENIC, SELENIUM, AND ANTIMONY, USING HYDRIDE GENERATION INTRODUCTION TO AN INDUCTIVELY COUPLED PLASMA.

    Science.gov (United States)

    Pyen, Grace S.; Browner, Richard F.; Long, Stephen

    1986-01-01

    A fixed-size simplex has been used to determine the optimum conditions for the simultaneous determination of arsenic, selenium, and antimony by hydride generation and inductively coupled plasma emission spectrometry. The variables selected for the simplex were carrier gas flow rate, rf power, viewing height, and reagent conditions. The detection limit for selenium was comparable to the preoptimized case, but there were twofold and fourfold improvements in the detection limits for arsenic and antimony, respectively. Precision of the technique was assessed with the use of artificially prepared water samples.

  7. Generation and acceleration of high-current annular electron beam in linear induction accelerator and generation of the power microwave radiation from Cherenkov TWT

    International Nuclear Information System (INIS)

    Abubakirov, E.V.; Arkhipov, O.V.; Bobyleva, L.V.

    1990-01-01

    The section of linear induction accelerator (LIA) with a strong guiding magnetic field (up to 1.5 T), with output beam power up to 2 GW and beam pulse duration 60 ns is created and investigated by experiment. The beam energy gain is equal to 10 keV/sm with explosive emission is used; the large length of the beam propagation (1.5 m) without spolling of the beam with high beam energy gain has been established. The microwave radiation power about 30-100 MW has achieved from relativistic Cherenkov travelling wave tube with high exponential gain on the basis of LIA and high-current diode

  8. NIMROD simulations and physics assessment of possible designs for a next generation Steady Inductive Helicity Injection HIT device

    Science.gov (United States)

    Penna, James; Morgan, Kyle; Grubb, Isaac; Jarboe, Thomas

    2017-10-01

    The Helicity Injected Torus - Steady Inductive 3 (HIT-SI3) experiment forms and maintains spheromaks via Steady Inductive Helicity Injection (SIHI) using discrete injectors that inject magnetic helicity via a non-axisymmetric perturbation and drive toroidally symmetric current. Newer designs for larger SIHI-driven spheromaks incorporate a set of injectors connected to a single external manifold to allow more freedom for the toroidal structure of the applied perturbation. Simulations have been carried out using the NIMROD code to assess the effectiveness of various imposed mode structures and injector schema in driving current via Imposed Dynamo Current Drive (IDCD). The results are presented here for varying flux conserver shapes on a device approximately 1.5 times larger than the current HIT-SI3 experiment. The imposed mode structures and spectra of simulated spheromaks are analyzed in order to examine magnetic structure and stability and determine an optimal regime for IDCD sustainment in a large device. The development of scaling laws for manifold operation is also presented, and simulation results are analyzed and assessed as part of the development path for the large scale device.

  9. The utilization of induction generators working with PATs (pumps working as turbines) in electric energy generation; A utilizacao de geradores de inducao acionados por BFTs (bombas funcionando como turbinas) na geracao de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Augusto Nelson Carvalho; Rezek, Angelo Jose Junqueira; Medeiros, Daniel de Macedo [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Programa de Pos-graduacao em Engenharia da Energia], e-mail: augusto@unifei.edu.br, e-mail: rezek@iee.efei.br, e-mail: macedo@unifei.edu.br

    2004-07-01

    The utilization of the Pumps working as Turbines (PATs) in micro hydro-energy resources to replace the conventional turbines as Pelton, Francis and Propeller have been used in countries as USA, Germany and France. In the mean time, in Brazil this practice and the utilization of induction generators working with PATs is still in the scope of the laboratory experiments. This work, based on experimental results carried on in Laboratory of Hydromechanics for Small Hydro Power Plants (Laboratorio Hidromecanico para Pequenas Centrais Hidroeletricas - LHPCH - UNIFEI), (VIANA, 1987), (VIANA e NOGUEIRA, 1990), propose the utilization of asynchronous generator groups operating with PATs. To show the investment cost decrease in micro hydro power plants (MHPs), is showed the Boa Esperanca MPH example, in which is presented a comparison between the synchronous generator group cost working with a Michell-Banki turbine and a asynchronous generator group operating with a PAT. (author)

  10. Development of coupling systems at the hybrid frequency for the non-inductive current generation inside a tokamak; Developpement de coupleurs a la frequence hybride pour la generation non inductive du courant dans un tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Berio, S. [Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee]|[Aix-Marseille-1 Univ., 13 - Marseille (France)

    1996-12-31

    Used at its first time as an heating method in order to reach the temperature requisite for the fusion of a thermonuclear plasma, the hybrid waves has shown that they were the more efficient method for non-inductive current drive in a tokamak. The size and the objectives of a next machine such as ITER lead to the design of new antennae (in process of realisation on Tore Supra) made of oversized waveguides. This new concept of antenna will be more simple, more robust and will be able to transmit the same if not much power than the present antennae. This thesis contribute to the development of a new code called ALOHA (for `Advanced LOwer Hybrid Antenna`) which, at the end, will be able to give the characteristics and the behaviours of this new oversized antennae in front of a tokamak plasma. This thesis is also a first step in the interpretation of some experimental data concerning the measurement of coupling, absorption and current drive of the actual hybrid wave launched by a grill with rectangular waveguides. Moreover, this thesis lay some foundations of the study of these new antennae in front of a on-parallel confinement magnetic field and/or in front of poloidal inhomogeneities of plasma. (authors) 53 refs.

  11. Calculation of temperature fields formed in induction annealing of closing welded joint of jacket of steam generator for WWER 440 type nuclear power plant using ICL 2960 computer

    International Nuclear Information System (INIS)

    Sajnar, P.; Fiala, J.

    1983-01-01

    The problems are discussed of the mathematical description and simulation of temperature fields in annealing the closing weld of the steam generator jacket of the WWER 440 nuclear power plant. The basic principles are given of induction annealing, the method of calculating temperature fields is indicated and the mathematical description is given of boundary conditions on the outer and inner surfaces of the steam generator jacket for the computation of temperature fields arising during annealing. Also described are the methods of determining the temperature of exposed parts of heat exchange tubes inside the steam generator and the technical possibilities are assessed of the annealing equipment from the point of view of its computer simulation. Five alternatives are given for the computation of temperature fields in the area around the weld for different boundary conditions. The values are given of maximum differences in the temperatures of the metal in the annealed part of the steam generator jacket which allow the assessment of individual computation variants, this mainly from the point of view of observing the course of annealing temperature in the required width of the annealed jacket of the steam generator along both sides of the closing weld. (B.S.)

  12. A new nebulization device with exchangeable aerosol generation mode as a useful tool to investigate sample introduction processes in inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Grotti, Marco; Lagomarsino, Cristina; Frache, Roberto

    2004-01-01

    A new sample introduction device has been designed in order to differentiate between the effects of the aerosol production and its following desolvation on analytical performances of an inductively coupled plasma optical spectrometer. This research tool allows to easily switch between the pneumatic and ultrasonic aerosol generation mode and to use a joint desolvation chamber. In this way, a real comparison between aerosol production systems may be attained and the influence of aerosol generation process on analytical figures clearly distinguished from that of the desolvation process. In this work, the separate effects of the aerosol generation and desolvation processes on analytical sensitivity and tolerance towards matrix effects have been investigated. Concerning sensitivity, it was found that both the processes play an important role in determining emission intensities, being the increase in sensitivity due to desolvation higher than that due to the improved aerosol generation efficiency. Concerning the matrix effects, a predominant role of the desolvation system was found, while the influence of the aerosol generation mode was much less important. For nitric acid, the decreasing effect was mitigated by the presence of a desolvation system, due to partial removal of the acid. On the contrary, the depressive effect of sulfuric acid was enhanced by the presence of a desolvation system, due to degradation of the solvent removal efficiency and to further decrease in the analyte transport rate caused by clustering phenomena. Concerning the interferences due to sodium and calcium, a depressive effect was observed, which is enhanced by desolvation

  13. Huge Inverse Magnetization Generated by Faraday Induction in Nano-Sized Au@Ni Core@Shell Nanoparticles.

    Science.gov (United States)

    Kuo, Chen-Chen; Li, Chi-Yen; Lee, Chi-Hung; Li, Hsiao-Chi; Li, Wen-Hsien

    2015-08-25

    We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the induced inverse magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before turning the magnetic field off, and can be as high as 54% of the magnetization prior to cutting off the applied magnetic field. Memory effect of the induced inverse magnetization is clearly revealed in the relaxation measurements. The relaxation of the inverse magnetization can be described by an exponential decay profile, with a critical exponent that can be effectively tuned by the wait time right after reaching the designated temperature and before the applied magnetic field is turned off. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction.

  14. Huge Inverse Magnetization Generated by Faraday Induction in Nano-Sized Au@Ni Core@Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Chen-Chen Kuo

    2015-08-01

    Full Text Available We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the induced inverse magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before turning the magnetic field off, and can be as high as 54% of the magnetization prior to cutting off the applied magnetic field. Memory effect of the induced inverse magnetization is clearly revealed in the relaxation measurements. The relaxation of the inverse magnetization can be described by an exponential decay profile, with a critical exponent that can be effectively tuned by the wait time right after reaching the designated temperature and before the applied magnetic field is turned off. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction.

  15. Huge Inverse Magnetization Generated by Faraday Induction in Nano-Sized Au@Ni Core@Shell Nanoparticles

    Science.gov (United States)

    Kuo, Chen-Chen; Li, Chi-Yen; Lee, Chi-Hung; Li, Hsiao-Chi; Li, Wen-Hsien

    2015-01-01

    We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the induced inverse magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before turning the magnetic field off, and can be as high as 54% of the magnetization prior to cutting off the applied magnetic field. Memory effect of the induced inverse magnetization is clearly revealed in the relaxation measurements. The relaxation of the inverse magnetization can be described by an exponential decay profile, with a critical exponent that can be effectively tuned by the wait time right after reaching the designated temperature and before the applied magnetic field is turned off. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction. PMID:26307983

  16. Faroe Islands Wind-Powered Space Heating Microgrid Using Self-Excited 220 kW Induction Generator

    DEFF Research Database (Denmark)

    Thomsen, Bjarti; Guerrero, Josep M.; Thogersen, Paul

    2014-01-01

    its own control of frequency and voltage. A micro-controller is used to control frequency by matching load (heaters) to generated power and to produce the correct reactive power and voltage by switched capacitors. One challenge is the startup procedure at high winds speeds when nominal speed tend...

  17. Determination of mercury in coal by isotope dilution cold-vapor generation inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Long, S.E.; Kelly, W.R.

    2002-04-01

    A method based on isotope dilution cold-vapor inductively coupled plasma mass spectrometry (ID-CV-ICPMS) has been developed for high-accuracy determinations of mercury in bituminous and sub-bituminous coals. A closed-system digestion process employing a Carius tube is used to completely oxidize the coal matrix and chemically equilibrate the mercury in the sample with a Hg-201 isotopic spike. The digestates are diluted with high-purity quartz-distilled water, and the mercury is released as a vapor by reduction with tin chloride. Measurements of Hg-201/Hg-202 isotope ratios are made using a quadrupole ICPMS system in time-resolved analysis mode. The new method has some significant advantages over existing methods. The instrument detection limit is less than 1 pg/mL. The average blank (n = 17) is 30 pg, which is roughly 1 order of magnitude lower than the equivalent microwave digestion procedure. The detection limit in coal is blank limited and is similar to 40 pg/g. Memory effects are very low. The relative reproducibility of the analytical measurements is similar to 0.5% for mercury concentrations in the range 10-150 ng/g. The method has been used to measure mercury concentrations in six coal reference materials, SRM 1632b (77.4 ng/g), SRM 1632c (94.3 ng/g), BCR 40 (433.2 ng/g), BCR 180 (125.0 ng/g), BCR 181 (135.8 ng/g), and SARM 20 (252.6 ng/g), as well as a coal fly ash, SRM 1633b (143.1 ng/g). The method is equally applicable to other types of fossil fuels including both crude and refined oils.

  18. Labor Induction

    Science.gov (United States)

    f AQ FREQUENTLY ASKED QUESTIONS FAQ154 LABOR, DELIVERY, AND POSTPARTUM CARE Labor Induction • What is labor induction? • Why is labor induced? • What is the Bishop score? • What is “ripening ...

  19. Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

    International Nuclear Information System (INIS)

    Huh, Sung-Ryul; Kim, Nam-Kyun; Jung, Bong-Ki; Chung, Kyoung-Jae; Hwang, Yong-Seok; Kim, Gon-Ho

    2015-01-01

    A global model was developed to investigate the densities of negative ions and the other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian electron energy distribution. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by high-energy electrons. This leads to a higher reaction rate of the dissociative electron attachment responsible for negative ion production. The model indicated that the bi-Maxwellian electron energy distribution at low pressures is favorable for the creation of negative ions. In addition, the electron temperature, electron density, and negative ion density calculated using the model were compared with the experimental data. In the low-pressure regime, the model results of the bi-Maxwellian electron energy distributions agreed well quantitatively with the experimental measurements, unlike those of the assumed Maxwellian electron energy distributions that had discrepancies

  20. Induction of peroxide and superoxide protective enzymes and physiological cross-protection against peroxide killing by a superoxide generator in Vibrio harveyi.

    Science.gov (United States)

    Vattanaviboon, Paiboon; Panmanee, Warunya; Mongkolsuk, Skorn

    2003-04-11

    Vibrio harveyi is a causative agent of destructive luminous vibriosis in farmed black tiger prawn (Penaeus monodon). V. harveyi peroxide and superoxide stress responses toward elevated levels of a superoxide generated by menadione were investigated. Exposure of V. harveyi to sub-lethal concentrations of menadione induced high expression of genes in both the OxyR regulon (e.g., a monofunctional catalase or KatA and an alkyl hydroperoxide reductase subunit C or AhpC), and the SoxRS regulon (e.g., a superoxide dismutase (SOD) and a glucose-6-phosphate dehydrogenase). V. harveyi expressed two detectable, differentially regulated SOD isozymes, [Mn]-SOD and [Fe]-SOD. [Fe]-SOD was expressed constitutively throughout the growth phase while [Mn]-SOD was expressed at the stationary phase and could be induced by a superoxide generator. Physiologically, pre-treatment of V. harveyi with menadione induced cross-protection against subsequent exposure to killing concentrations of H(2)O(2). This induced cross-protection required newly synthesized proteins. However, the treatment did not induce significant protection against exposures to killing concentrations of menadione itself or cross-protect against an organic hydroperoxide (tert-butyl hydroperoxide). Unexpectedly, growing V. harveyi in high-salinity media induced protection against menadione killing. This protection was independent of SOD induction. Stationary-phase cells were more resistant to menadione killing than exponential-phase cells. The induction of oxidative stress protective enzymes and stress-altered physiological responses could play a role in the survival of this bacterium in the host marine crustaceans.

  1. Modeling, control and fault diagnosis of an isolated wind energy conversion system with a self-excited induction generator subject to electrical faults

    International Nuclear Information System (INIS)

    Attoui, Issam; Omeiri, Amar

    2014-01-01

    Highlights: • A new model of the SEIG is developed to simulate both the rotor and stator faults. • This model takes iron loss, main flux and cross flux saturation into account. • A new control strategy based on Fractional-Order Controller (FOC) is proposed. • The control strategy is developed for the control of the wind turbine speed. • An on-line diagnostic procedure based on the stator currents analysis is presented. - Abstract: In this paper, a contribution to modeling and fault diagnosis of rotor and stator faults of a Self-Excited Induction Generator (SEIG) in an Isolated Wind Energy Conversion System (IWECS) is proposed. In order to control the speed of the wind turbine, while basing on the linear model of wind turbine system about a specified operating point, a new Fractional-Order Controller (FOC) with a simple and practical design method is proposed. The FOC ensures the stability of the nonlinear system in both healthy and faulty conditions. Furthermore, in order to detect the stator and rotor faults in the squirrel-cage self-excited induction generator, an on-line fault diagnostic technique based on the spectral analysis of stator currents of the squirrel-cage SEIG by a Fast Fourier Transform (FFT) algorithm is used. Additionally, a generalized model of the squirrel-cage SEIG is developed to simulate both the rotor and stator faults taking iron loss, main flux and cross flux saturation into account. The efficiencies of generalized model, control strategy and diagnostic procedure are illustrated with simulation results

  2. Induction linacs

    International Nuclear Information System (INIS)

    Keefe, D.

    1986-07-01

    The principle of linear induction acceleration is described, and examples are given of practical configurations for induction linacs. These examples include the Advanced Technology Accelerator, Long Pulse Induction Linac, Radial Line Accelerator (RADLAC), and Magnetically-Insulated Electron-Focussed Ion Linac. A related concept, the auto accelerator, is described in which the high-current electron-beam technology in the sub-10 MeV region is exploited to produce electron beams at energies perhaps as high as the 100 to 1000 MeV range. Induction linacs for ions are also discussed. The efficiency of induction linear acceleration is analyzed

  3. Determination of lead by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS): On-line generation of plumbane using potassium hexacyanomanganate(III)

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Vedat [Jackson State University, Department of Chemistry and Biochemistry, Jackson, MS 39217 (United States); Erciyes University, Faculty of Pharmacy, Department of Analytical Chemistry, 38039 Kayseri (Turkey); Arslan, Zikri, E-mail: zikri.arslan@jsums.edu [Jackson State University, Department of Chemistry and Biochemistry, Jackson, MS 39217 (United States); Rose, LaKeysha [Jackson State University, Department of Chemistry and Biochemistry, Jackson, MS 39217 (United States)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer Potassium hexacyanomanganate(III), (K{sub 3}Mn(CN){sub 6}, was utilized first time for hydride generation (HG). Black-Right-Pointing-Pointer Hexacyanomanganate(III) promoted generation of lead hydride (PbH{sub 4}) remarkably. Black-Right-Pointing-Pointer The HG method using K{sub 3}Mn(CN){sub 6} enhanced sensitivity by at least 40-fold. Black-Right-Pointing-Pointer The method detection limits for Pb were as low as 8 ng L{sup -1} by ICP-MS. Black-Right-Pointing-Pointer The method is highly suitable for quantitative determination of Pb in various samples and salt matrices by ICP-MS. - Abstract: A hydride generation (HG) procedure has been described for determination of Pb by ICP-MS using potassium hexacyanomanganate(III), K{sub 3}Mn(CN){sub 6}, as an additive to facilitate the generation of plumbane (PbH{sub 4}). Potassium hexacyanomanganate(III) was prepared in acidic medium as it was unstable in water. The stability of hexacyanomanganate(III) was examined in dilute solutions of HCl, HNO{sub 3} and H{sub 2}SO{sub 4}. The solutions prepared in 1% v/v H{sub 2}SO{sub 4} were found to be stable for over a period of 24 h. The least suitable medium was 1% v/v HNO{sub 3}. For generation of plumbane, acidic hexacyanomanganate(III) and sample solutions were mixed on-line along a 5-cm long tygon tubing (1.14 mm i.d.) and then reacted with 2% m/v sodium borohydride (NaBH{sub 4}). A concentration of 0.5% m/v K{sub 3}Mn(CN){sub 6} facilitated the generation of PbH{sub 4} remarkably. In comparison to H{sub 2}SO{sub 4}, HCl provided broader working range for which optimum concentration was 1% v/v. No significant interferences were noted from transition metals and hydride forming elements, up to 0.5 {mu}g mL{sup -1} levels, except Cu which depressed the signals severely. The depressive effects in the presence of 0.1 {mu}g mL{sup -1} Cu were alleviated by increasing the concentration of K{sub 3}Mn(CN){sub 6} to 2% m/v. Under these conditions

  4. Induction of apoptosis and antiproliferative activity of naringenin in human epidermoid carcinoma cell through ROS generation and cell cycle arrest.

    Directory of Open Access Journals (Sweden)

    Md Sultan Ahamad

    Full Text Available A natural predominant flavanone naringenin, especially abundant in citrus fruits, has a wide range of pharmacological activities. The search for antiproliferative agents that reduce skin carcinoma is a task of great importance. The objective of this study was to analyze the anti-proliferative and apoptotic mechanism of naringenin using MTT assay, DNA fragmentation, nuclear condensation, change in mitochondrial membrane potential, cell cycle kinetics and caspase-3 as biomarkers and to investigate the ability to induce reactive oxygen species (ROS initiating apoptotic cascade in human epidermoid carcinoma A431 cells. Results showed that naringenin exposure significantly reduced the cell viability of A431 cells (p<0.01 with a concomitant increase in nuclear condensation and DNA fragmentation in a dose dependent manner. The intracellular ROS generation assay showed statistically significant (p<0.001 dose-related increment in ROS production for naringenin. It also caused naringenin-mediated epidermoid carcinoma apoptosis by inducing mitochondrial depolarization. Cell cycle study showed that naringenin induced cell cycle arrest in G0/G1 phase of cell cycle and caspase-3 analysis revealed a dose dependent increment in caspase-3 activity which led to cell apoptosis. This study confirms the efficacy of naringenin that lead to cell death in epidermoid carcinoma cells via inducing ROS generation, mitochondrial depolarization, nuclear condensation, DNA fragmentation, cell cycle arrest in G0/G1 phase and caspase-3 activation.

  5. Half Bridge Inductive Heater

    Directory of Open Access Journals (Sweden)

    Zoltán GERMÁN-SALLÓ

    2015-12-01

    Full Text Available Induction heating performs contactless, efficient and fast heating of conductive materials, therefore became one of the preferred heating procedure in industrial, domestic and medical applications. During induction heating the high-frequency alternating currents that heat the material are induced by means of electromagnetic induction. The material to be heated is placed inside the time-varying magnetic field generated by applying a highfrequency alternating current to an induction coil. The alternating electromagnetic field induces eddy currents in the workpiece, resulting resistive losses, which then heat the material. This paper describes the design of a power electronic converter circuit for induction heating equipment and presents the obtained results. The realized circuit is a low power half bridge resonant inverter which uses power MOS transistors and adequate driver circuits.

  6. UVA Photoirradiation of Oxygenated Benz[a]anthracene and 3-Methylcholanthene - Generation of Singlet Oxygen and Induction of Lipid Peroxidation

    Directory of Open Access Journals (Sweden)

    Diógenes Herreño Sáenz

    2008-03-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs are widespread genotoxic environmental pollutants and potentially pose a health risk to humans. Although the biological and toxicological activities, including metabolism, mutagenicity, and carcinogenicity, of PAHs have been thoroughly studied, their phototoxicity and photo-induced biological activity have not been well examined. We have long been interested in phototoxicity of PAHs and their derivatives induced by irradiation with UV light. In this paper we report the photoirradiation of a series of oxygenated benz[a]anthracene (BA and 3-methylcholanthene (3-MC by UVA light in the presence of a lipid, methyl linoleate. The studied PAHs include 2-hydroxy-BA (2-OH-BA, 3-hydroxy-BA (3-OH-BA, 5-hydroxymethyl-BA (5-CH2OH-BA, 7-hydroxymethyl-BA (7-CH2OH-BA, 12-hydroxymethyl-BA (12-CH2OH-BA, 7-hydroxymethyl-12-methyl-BA (7-CH2OH-12-MBA, 5-formyl-BA (5-CHO-BA, BA 5,6-cis-dihydrodiol (BA 5,6-cis-diol, 1-hydroxy-3- methylcholanthene (1-OH-3-MC, 1-keto-3-methylcholanthene (1-keto-3-MC, and 3-MC 1,2-diol. The results indicate that upon photoirradiation by UVA at 7 and 21 J/cm2, respectively all these compounds induced lipid peroxidation and exhibited a relationship between the dose of the light and the level of lipid peroxidation induced. To determine whether or not photoirradiation of these compounds by UVA light produces ROS, an ESR spin-trap technique was employed to provide direct evidence. Photoirradiation of 3-keto-3-MC by UVA (at 389 nm in the presence of 2,2,6,6-tetramethylpiperidine (TEMP, a specific probe for singlet oxygen, resulted in the formation of TEMPO, indicating that singlet oxygen was generated. These overall results suggest that UVA photoirradiation of oxygenated BA and 3-methylcholanthrene generates singlet oxygen, one of the reactive oxygen species (ROS, which induce lipid peroxidation.

  7. Design and Implementation of Improved Electronic Load Controller for Self-Excited Induction Generator for Rural Electrification

    Directory of Open Access Journals (Sweden)

    C. Kathirvel

    2015-01-01

    Full Text Available This paper offers an alternative technique, namely, Improved Electronic Load Controller (IELC, which is proposal to improve power quality, maintaining voltage at frequency desired level for rural electrification. The design and development of IELC are considered as microhydroenergy system. The proposed work aims to concentrate on the new schemes for rural electrification with the help of different kinds of hybrid energy systems. The objective of the proposed scheme is to maintain the speed of generation against fluctuating rural demand. The Electronic Load Controller (ELC is used to connect and disconnect the dump load during the operation of the system, and which absorbs the load when consumer are not in active will enhance the lifestyle of the rural population and improve the living standards. Hydroelectricity is a promising option for electrification of remote villages in India. The conventional methods are not suitable to act as standalone system. Hence, the designing of a proper ELC is essential. The improved electronic load control performance tested with simulation at validated through hardware setup.

  8. Design and Implementation of Improved Electronic Load Controller for Self-Excited Induction Generator for Rural Electrification.

    Science.gov (United States)

    Kathirvel, C; Porkumaran, K; Jaganathan, S

    2015-01-01

    This paper offers an alternative technique, namely, Improved Electronic Load Controller (IELC), which is proposal to improve power quality, maintaining voltage at frequency desired level for rural electrification. The design and development of IELC are considered as microhydroenergy system. The proposed work aims to concentrate on the new schemes for rural electrification with the help of different kinds of hybrid energy systems. The objective of the proposed scheme is to maintain the speed of generation against fluctuating rural demand. The Electronic Load Controller (ELC) is used to connect and disconnect the dump load during the operation of the system, and which absorbs the load when consumer are not in active will enhance the lifestyle of the rural population and improve the living standards. Hydroelectricity is a promising option for electrification of remote villages in India. The conventional methods are not suitable to act as standalone system. Hence, the designing of a proper ELC is essential. The improved electronic load control performance tested with simulation at validated through hardware setup.

  9. Inductive reasoning.

    Science.gov (United States)

    Hayes, Brett K; Heit, Evan; Swendsen, Haruka

    2010-03-01

    Inductive reasoning entails using existing knowledge or observations to make predictions about novel cases. We review recent findings in research on category-based induction as well as theoretical models of these results, including similarity-based models, connectionist networks, an account based on relevance theory, Bayesian models, and other mathematical models. A number of touchstone empirical phenomena that involve taxonomic similarity are described. We also examine phenomena involving more complex background knowledge about premises and conclusions of inductive arguments and the properties referenced. Earlier models are shown to give a good account of similarity-based phenomena but not knowledge-based phenomena. Recent models that aim to account for both similarity-based and knowledge-based phenomena are reviewed and evaluated. Among the most important new directions in induction research are a focus on induction with uncertain premise categories, the modeling of the relationship between inductive and deductive reasoning, and examination of the neural substrates of induction. A common theme in both the well-established and emerging lines of induction research is the need to develop well-articulated and empirically testable formal models of induction. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.

  10. SPECIATION OF SELENIUM AND ARSENIC COMPOUNDS BY CAPILLARY ELECTROPHORESIS WITH HYDRODYNAMICALLY MODIFIED ELECTROOSMOTIC FLOW AND ON-LINE REDUCTION OF SELENIUM(VI) TO SELENIUM(IV) WITH HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    Science.gov (United States)

    Capillary electrophoresis (CE) with hydride generation inductively coupled plasma mass spectrometry was used to determine four arsenicals and two selenium species. Selenate (SeVI) was reduced on-line to selenite (SeIV') by mixing the CE effluent with concentrated HCl. A microporo...

  11. Teacher induction

    NARCIS (Netherlands)

    Beijaard, D.; Buitink, J.; Kessels, C.; Peterson, P.; Baker, E.; McGraw, B.

    2010-01-01

    Teacher induction programs are intended to support the professional development of beginning teachers and thereby contribute to the reduction of teacher attrition during the early teaching years. Teacher induction programs are often based upon a deficit model with a focus on the better organization

  12. Development of novel and sensitive methods for the determination of sulfide in aqueous samples by hydrogen sulfide generation-inductively coupled plasma-atomic emission spectroscopy.

    Science.gov (United States)

    Colon, M; Todolí, J L; Hidalgo, M; Iglesias, M

    2008-02-25

    Two new, simple and accurate methods for the determination of sulfide (S(2-)) at low levels (microgL(-1)) in aqueous samples were developed. The generation of hydrogen sulfide (H(2)S) took place in a coil where sulfide reacted with hydrochloric acid. The resulting H(2)S was then introduced as a vapor into an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and sulfur emission intensity was measured at 180.669nm. In comparison to when aqueous sulfide was introduced, the introduction of sulfur as H(2)S enhanced the sulfur signal emission. By setting a gas separator at the end of the reaction coil, reduced sulfur species in the form of H(2)S were removed from the water matrix, thus, interferences could be avoided. Alternatively, the gas separator was replaced by a nebulizer/spray chamber combination to introduce the sample matrix and reagents into the plasma. This methodology allowed the determination of both sulfide and sulfate in aqueous samples. For both methods the linear response was found to range from 5microgL(-1) to 25mgL(-1) of sulfide. Detection limits of 5microgL(-1) and 6microgL(-1) were obtained with and without the gas separator, respectively. These new methods were evaluated by comparison to the standard potentiometric method and were successfully applied to the analysis of reduced sulfur species in environmental waters.

  13. Optimization of a single-drop microextraction method for multielemental determination by electrothermal vaporization inductively coupled plasma mass spectrometry following in situ vapor generation

    International Nuclear Information System (INIS)

    Gil, Sandra; Loos-Vollebregt, Margaretha T.C. de; Bendicho, Carlos

    2009-01-01

    A headspace single-drop microextraction (HS-SDME) method has been developed in combination with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the simultaneous determination of As, Sb, Bi, Pb, Sn and Hg in aqueous solutions. Vapor generation is carried out in a 40 mL volume closed-vial containing a solution with the target analytes in hydrochloric acid and potassium ferricyanide medium. Hydrides (As, Sb, Bi, Pb, Sn) and Hg vapor are trapped onto an aqueous single drop (3 μL volume) containing Pd(II), followed by the subsequent injection in the ETV. Experimental variables such as medium composition, sodium tetrahydroborate (III) volume and concentration, stirring rate, extraction time, sample volume, ascorbic acid concentration and palladium amount in the drop were fully optimized. The limits of detection (LOD) (3σ criterion) of the proposed method for As, Sb, Bi, Pb, Sn and Hg were 0.2, 0.04, 0.01, 0.07, 0.09 and 0.8 μg/L, respectively. Enrichment factors of 9, 85, 138, 130, 37 and 72 for As, Sb, Bi, Pb, Sn and Hg, respectively, were achieved in 210 s. The relative standard deviations (N = 5) ranged from 4 to 8%. The proposed HS-SDME-ETV-ICP-MS method has been applied for the determination of As, Sb, Bi, Pb, Sn and Hg in NWRI TM-28.3 certified reference material.

  14. Vibrational Dynamics of Interfacial Water by Free Induction Decay Sum Frequency Generation (FID-SFG) at the Al2O3(1120)/H2O Interface.

    Science.gov (United States)

    Boulesbaa, Abdelaziz; Borguet, Eric

    2014-02-06

    The dephasing dynamics of a vibrational coherence may reveal the interactions of chemical functional groups with their environment. To investigate this process at a surface, we employ free induction decay sum frequency generation (FID-SFG) to measure the time that it takes for free OH stretch oscillators at the charged (pH ≈ 13, KOH) interface of alumina/water (Al2O3/H2O) to lose their collective coherence. By employing noncollinear optical parametric amplification (NOPA) technology and nonlinear vibrational spectroscopy, we showed that the single free OH peak actually corresponds to two distinct oscillators oriented opposite to each other and measured the total dephasing time, T2, of the free OH stretch modes at the Al2O3/H2O interface with a sub-40 fs temporal resolution. Our results suggested that the free OH oscillators associated with interfacial water dephase on the time scale of 89.4 ± 6.9 fs, whereas the homogeneous dephasing of interfacial alumina hydroxyls is an order of magnitude slower.

  15. Reduced-Capacity Inrush Current Suppressor Using a Matrix Converter in a Wind Power Generation System with Squirrel-Cage Induction Machines

    Directory of Open Access Journals (Sweden)

    Sho Shibata

    2016-03-01

    Full Text Available This paper describes the reduced capacity of the inrush current suppressor using a matrix converter (MC in a large-capacity wind power generation system (WPGS with two squirrel-cage induction machines (SCIMs. These SCIMs are switched over depending on the wind speed. The input side of the MC is connected to the source in parallel. The output side of the MC is connected in series with the SCIM through matching transformers. The modulation method of the MC used is direct duty ratio pulse width modulation. The reference output voltage of the MC is decided by multiplying the SCIM current with the variable control gain. Therefore, the MC performs as resistors for the inrush current. Digital computer simulation is implemented to confirm the validity and practicability of the proposed inrush current suppressor using PSCAD/EMTDC (power system computer-aided design/electromagnetic transients including DC. Furthermore, the equivalent resistance of the MC is decided by the relationship between the equivalent resistance and the capacity of the MC. Simulation results demonstrate that the proposed inrush current suppressor can suppress the inrush current perfectly.

  16. Control of offshore wind farms with HVDC grid connection

    Energy Technology Data Exchange (ETDEWEB)

    Weigel, Stefan; Weise, Bernd; Poeller, Markus [DIgSILENT GmbH, Gomaringen (Germany)

    2010-07-01

    This paper analyzes various aspects related to the operation of HVDC connected offshore wind farms. The main interest is on the behavior during on- and offshore faults. Different control strategies for VSC-HVDC and ''classical'' thyristor-based HVDC links are presented and analyzed via network simulations. Wind generators with fully-rated converters and wind generators with doubly-fed induction generators are considered as generator types. The feasibility, advantages and disadvantages of the various options are discussed in detail. (orig.)

  17. Evaluation of slurry preparation procedures for the determination of mercury by axial view inductively coupled plasma optical emission spectrometry using on-line cold vapor generation

    International Nuclear Information System (INIS)

    Santos, Eder Jose dos; Herrmann, Amanda Beatriz; Antunes Vieira, Mariana; Azzolin Frescura, Vera Lucia; Curtius, Adilson Jose

    2005-01-01

    Five different slurry preparation procedures were tested, after grinding the solid samples to a particle size ≤53 μm: (1) using aqua regia plus HF, 30 min of sonication, standing time of 24 h followed by another 30 min of sonication; (2) same as the previous one, except that the standing time and the second ultrasound treatment were omitted; (3) same as the previous one, except that HF was not used; (4) same as the previous one, except that the aqua regia was replaced by nitric acid; (5) same as the previous one, except that the acid nitric was replaced by tetramethylammonium hydroxide (TMAH). The Hg vapor was generated on-line, and the emission signal intensity measured at 253.652 nm by axial view inductively coupled plasma optical emission spectrometry. Initially, four experimental conditions were optimized using a multivariate factorial analysis: the concentrations of HCl and of the reducing agent, NaBH 4 , used in the cold vapor generation, and two instrumental parameters, the plasma radiofrequency power and the carrier gas flow rate. The radiofrequency power was statistically significant, but limited to 1.2 kW for practical reasons. The procedures were applied to 11 biological and environmental materials. Both, the slurries and the filtrates were analyzed, using calibration solutions in the same medium as in the slurries. The first three procedures produced results in agreement with the certified values. The two last procedures, using nitric acid or TMHA could not be used for quantitative analysis. For practical reasons, Procedure 3, with a detection limit (3s, n=10) of 0.06 μg g -1 for a sample mass of 20 mg in a final volume of 15 mL is recommended. The relative standard deviations for mercury in the investigated materials, using the recommended procedure, were lower than 12.5%, indicating a good precision for slurry sampling. The recommended procedure is simple, rapid and robust

  18. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ni [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Jiang, Shiuh-Jen, E-mail: sjjiang@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Chen, Yen-Ling [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Sahayam, A.C. [National Centre for Compositional Characterisation of Materials (CCCM), Hyderabad (India)

    2015-02-20

    Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL{sup −1} Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g{sup −1} for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.

  19. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

    International Nuclear Information System (INIS)

    Chen, Wei-Ni; Jiang, Shiuh-Jen; Chen, Yen-Ling; Sahayam, A.C.

    2015-01-01

    Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL −1 Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g −1 for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample

  20. Journal of Fundamental and Applied Sciences - Vol 2, No 2 (2010)

    African Journals Online (AJOL)

    Integrated management of water resources in the valley of Oued-Souf ... Application of a particle swarm optimization in an optimal power flow · EMAIL FREE FULL ... Fuzzy sliding mode controller for doubly fed induction motor speed control ...

  1. Comparison of 2D and 3D neural induction methods for the generation of neural progenitor cells from human induced pluripotent stem cells

    DEFF Research Database (Denmark)

    Chandrasekaran, Abinaya; Avci, Hasan; Ochalek, Anna

    2017-01-01

    Neural progenitor cells (NPCs) from human induced pluripotent stem cells (hiPSCs) are frequently induced using 3D culture methodologies however, it is unknown whether spheroid-based (3D) neural induction is actually superior to monolayer (2D) neural induction. Our aim was to compare the efficiency......), cortical layer (TBR1, CUX1) and glial markers (SOX9, GFAP, AQP4). Electron microscopy demonstrated that both methods resulted in morphologically similar neural rosettes. However, quantification of NPCs derived from 3D neural induction exhibited an increase in the number of PAX6/NESTIN double positive cells...... the electrophysiological properties between the two induction methods. In conclusion, 3D neural induction increases the yield of PAX6+/NESTIN+ cells and gives rise to neurons with longer neurites, which might be an advantage for the production of forebrain cortical neurons, highlighting the potential of 3D neural...

  2. Induction of Metallothionein Expression After Exposure to Conventional Cigarette Smoke but Not Electronic Cigarette (ECIG-Generated Aerosol in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Eric Cobb

    2018-04-01

    Full Text Available Aim: With the invention of electronic cigarettes (ECIG, many questions have been raised regarding their safety as an alternative to smoking conventional cigarettes. Conventional cigarette smoke contains a variety of toxicants including heavy metals. However, ECIG-generated aerosol contains only trace amounts of metals, adding to the argument for it being a safer alternative. In response to heavy metal exposure, metallothioneins are induced in cells to help store the metal, detoxify the body, and are also known responders to oxidative stress. In an attempt to add to the evaluation of the safety of ECIGs, metallothionein expression was quantified using the nematode Caenorhabditis elegans as an assessment of stress induced cellular damage caused by exposure.Methods: Adult nematodes were exposed to either ECIG aerosol or conventional cigarette smoke at doses of 15, 30, and 45 puffs, the equivalent of one, two, and three cigarettes, respectively. Movement, survival, and stress-induced sleep were assessed for up to 24 h after exposure. Relative expression levels for mtl-1 and mtl-2, C. elegans metallothionein genes, were analyzed after 1, 5, and 24 h post exposure using quantitative RT-PCR.Results: Nematodes exposed to conventional cigarette smoke underwent stress-induced sleep in a dose dependent manner with animals recovering to values within the range of air control after 5 h post exposure. Those exposed to ECIG aerosol did not undergo stress-induced sleep and were indistinguishable from controls. The expression of mtl-1 increased in a dose and time dependent manner in C. elegans exposed to conventional cigarette smoke, with a maximum expression observed at 5 h post exposure of 45 puffs. No induction of mtl-2 was observed in any animals. Additionally, ECIG aerosol did not induce expression of mtl-1 and mtl-2 at levels different than those of untreated.Conclusion: ECIG aerosol failed to induce a stress response in C. elegans. In contrast

  3. Control voltage of the generator of auto-excited induction for applications on micro/mini generation o electric power; Control de voltaje del generador de induccion auto-excitado para aplicaciones de micro/mini generacion de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Torres Montalvo, Emmanuel

    2006-09-15

    Although only one part of the mini/micro hydraulic power has been exploited in our country, this type of electric energy generation can be considered as a visible way of electricity generation, mainly related to the ecological, economical and social aspects. The impact that these power plants can have in the regions in which they are installed is always positive: cost energy cost reduction, economical spills and mainly a social welfare. The electric energy is one of the pillars for the economical development of a country and provides a better life quality. Nowadays the research and the technology oriented to the operation and control of the micro/mini power plants has awaken the interest of many researchers in several countries of the world as China, India, Canada, and USA to mention some of them. The induction generator plays a crucial role in the uses of these technologies. The work of Basset and Potter in 1935 is the angular stone over the possibility of generating energy making use of the induction machine and a capacitors bank connected to the machine terminals. This configuration is known as induction auto-excited generator (GIAE). Several investigations have been realized that deal about the functioning principle and the dynamic behavior a GIAE, which can supply electric power in remote isolated regions. In the existing literature have been proposed control strategies to offer voltage regulations and/or frequency into the acceptable range. Some of these control strategies present problems such a demand of a reactive power, harmonics injections in the system, the control circuits are complicated, expensive and voluminous and prone to fail. This paper realizes an analysis of the necessary and sufficient conditions so that an induction machine can operate as GIAE. The corresponding curves are presented for each studied case. The dynamic behavior of the voltage and the frequency generated by the GIAE are studied in detail, which is a contribution to the existing

  4. Modeling and Control of a DFIG-Based Wind Turbine During a Grid Voltage Drop

    Directory of Open Access Journals (Sweden)

    M. Shahabi

    2011-10-01

    Full Text Available Doubly-fed induction generators (DFIG are widely used in wind energy generation systems. During a grid voltage drop, performance is degraded with rotor over current deteriorating the fault-ride through (FRT capability of the DFIG wind-energy generation system. In this paper, a complete mathematical DFIG model is proposed. The rotor is considered fed by a voltage source converter whereas the stator is connected to the grid directly. Output power and electromagnetic torque are controlled using field-oriented control (FOC. Simulation results show the efficiency of the controller in exploiting the maximum power of wind.

  5. Development of novel and sensitive methods for the determination of sulfide in aqueous samples by hydrogen sulfide generation-inductively coupled plasma-atomic emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Colon, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Todoli, J.L. [Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Iglesias, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain)], E-mail: monica.iglesias@udg.es

    2008-02-25

    Two new, simple and accurate methods for the determination of sulfide (S{sup 2-}) at low levels ({mu}g L{sup -1}) in aqueous samples were developed. The generation of hydrogen sulfide (H{sub 2}S) took place in a coil where sulfide reacted with hydrochloric acid. The resulting H{sub 2}S was then introduced as a vapor into an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and sulfur emission intensity was measured at 180.669 nm. In comparison to when aqueous sulfide was introduced, the introduction of sulfur as H{sub 2}S enhanced the sulfur signal emission. By setting a gas separator at the end of the reaction coil, reduced sulfur species in the form of H{sub 2}S were removed from the water matrix, thus, interferences could be avoided. Alternatively, the gas separator was replaced by a nebulizer/spray chamber combination to introduce the sample matrix and reagents into the plasma. This methodology allowed the determination of both sulfide and sulfate in aqueous samples. For both methods the linear response was found to range from 5 {mu}g L{sup -1} to 25 mg L{sup -1} of sulfide. Detection limits of 5 {mu}g L{sup -1} and 6 {mu}g L{sup -1} were obtained with and without the gas separator, respectively. These new methods were evaluated by comparison to the standard potentiometric method and were successfully applied to the analysis of reduced sulfur species in environmental waters.

  6. Sampling Assumptions in Inductive Generalization

    Science.gov (United States)

    Navarro, Daniel J.; Dry, Matthew J.; Lee, Michael D.

    2012-01-01

    Inductive generalization, where people go beyond the data provided, is a basic cognitive capability, and it underpins theoretical accounts of learning, categorization, and decision making. To complete the inductive leap needed for generalization, people must make a key "sampling" assumption about how the available data were generated.…

  7. From Inductive Reasoning to Proof

    Science.gov (United States)

    Yopp, David A.

    2009-01-01

    Mathematical proof is an expression of deductive reasoning (drawing conclusions from previous assertions). However, it is often inductive reasoning (conclusions drawn on the basis of examples) that helps learners form their deductive arguments, or proof. In addition, not all inductive arguments generate more formal arguments. This article draws a…

  8. Releasable Kinetic Energy-Based Inertial Control of a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Lee, Jinsik; Muljadi, Eduard; Sørensen, Poul Ejnar

    2016-01-01

    Wind turbine generators (WTGs) in a wind power plant (WPP) contain different levels of releasable kinetic energy (KE) because of the wake effects. This paper proposes a releasable KE-based inertial control scheme for a doubly fed induction generator (DFIG) WPP that differentiates the contributions....... The proposed scheme adjusts the two loop gains in a DFIG controller depending on its rotor speed so that a DFIG operating at a higher rotor speed releases more KE. The performance of the proposed scheme was investigated under various wind conditions. The results clearly indicate that the proposed scheme...

  9. Overview of DFIG-based Wind Power System Resonances under Weak Networks

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2017-01-01

    The wind power generation techniques are continuing to develop and increasing numbers of Doubly Fed Induction Generator (DFIG)-based wind power systems are connecting to the on-shore and off-shore grids, local standalone weak networks, and also micro grid applications. The impedances of the weak...... scale of DFIG system with different parameters; 3) L or LCL filter adopted in the Grid Side Converter (GSC); 4) rotor speed; 5) current closed-loop controller parameters and 6) digital control delay will be discussed in this paper. On the basis of the analysis, active damping strategies for HFR using...

  10. Analysis of the Behavior of Undamped and Unstable High-Frequency Resonance in DFIG System

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2017-01-01

    As the wind power generation develops, the Doubly Fed Induction Generator (DFIG) based wind power system may suffer Sub Synchronous Resonance (SSR) and High Frequency Resonance (HFR) in the series and parallel compensated weak network. The principle and frequency of HFR have been discussed using...... the Bode diagram as an analysis tool. However, the HFR can be categorized into two different types: undamped HFR (which exists in steady state) and unstable HFR (which eventually results in complete instability and divergence), both of them are not investigated before. Since both the undamped HFR...

  11. Improving Fault Ride-Through Capability of Variable Speed Wind Turbines in Distribution Networks

    DEFF Research Database (Denmark)

    Mokryani, Geev; Siano, P.; Piccolo, Antonio

    2013-01-01

    In this paper, a fuzzy controller for improving the fault ride-through (FRT) capability of variable speed wind turbines (WTs) equipped with a doubly fed induction generator (DFIG) is presented. DFIGs can be used as reactive power sources to control the voltage at the point of common coupling (PCC......). The controller is designed to compensate for the voltage at the PCC by simultaneously regulating the reactive and active power generated by WTs. The performance of the controller is evaluated in different case studies considering a different number of wind farms in different locations. Simulations carried out...

  12. A COMPARATIVE ANALYSIS OF PROCESSES IN AN INDEPENDENT GENERATOR WITH A NONCONTACT CASCADE THREE-PHASE MODULATED EXCITER VIA A STAR-CONNECTED CIRCUIT UNDER ACTIVE-INDUCTIVE LOADING

    Directory of Open Access Journals (Sweden)

    K.M. Vasyliv

    2013-02-01

    Full Text Available By means of mathematical experiment, the author investigates electromagnetic and electromechanical processes in an independent electric power supply system based on an asynchronized generator with a three-phase modulated exciter. The processes are analyzed to specify the working capacity of the power supply system during its operation under active-inductive loading. Regularities of the electromagnetic and electromechanical processes behavior versus load intensity and the modulator scheme are identified.

  13. ANALYSIS OF PROCESSES IN AN INDEPENDENT GENERATOR WITH A NONCONTACT CASCADE THREE-PHASE MODULATED EXCITER VIA A STAR-CONNECTED CIRCUIT WITH A COMMON MODULATOR PHASE CONNECTION UNDER OPERATION TO AN INDUCTION MOTORS SITE

    Directory of Open Access Journals (Sweden)

    K.M. Vasyliv

    2013-04-01

    Full Text Available By means of a mathematical experiment, electromagnetic and electromechanical processes in an independent electric power supply system based on an asynchronized generator with a three-phase modulated exciter are investigated. The processes are analyzed to specify the working capacity of the power supply system during its operation to an induction motors site. Regularities of the electromagnetic and electromechanical processes behavior versus load intensity and the switch control system parameters are identified.

  14. Influence of generated harmonics in the performance of three-phase induction motor using chopper in the rotor circuit; Influencia dos harmonicos gerados no desempenho do motor de inducao trifasico utilizando chopper no circuito rotorico

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Antonio Tadeu Lyrio de; Sa, Jocelio Souza de; Abreu, Jose Policarpo G. de; Lamoglia, Jose Augusto [Escola Federal de Engenharia de Itajuba, MG (Brazil). Dept. de Engenharia e Tecnologia

    1988-12-31

    One of the alternatives for the speed control of an induction motor is the insertion of a converter regulator of direct current (chopper) in the rotor. The utilization of a rectifier bridge in this circuit generates electric current harmonics. This work analyses its influence on the motor performance. The general equating, whenever possible, is based on the national manufactures catalogue data 2 refs., 6 figs.

  15. Induction practice -

    DEFF Research Database (Denmark)

    Rohde, Nicolas; Sprogøe, Jonas

    2007-01-01

    that induction potentially triggers both individual and organizational learning and by drawing on practice-based theory we discuss how the interplay between individual and the organization, what we call agenerative dance, ignites both kinds of learning. We focus on and describe the interplay , ignites both kinds...

  16. Comparative oxidation state specific analysis of arsenic species by high-performance liquid chromatography-inductively coupled-mass spectrometry and hydride generation-cryotrapping-atomic absorption spectrometry

    Science.gov (United States)

    The formation of methylarsonous acid (MAsIII) and dimethylarsinous acid (DMAsIII) in the course of inorganic arsenic (iAs) metabolism plays an important role in the adverse effects of chronic exposure to iAs. High-performance liquid chromatography-inductively coupled plasma-mass ...

  17. Induction Brazing

    DEFF Research Database (Denmark)

    Henningsen, Poul

    , or if the hottest area is located outside the joint interface, a number of defects may appear: the braze metal may flow away from the joint, the flux may burn off, poor binding of the braze metal may appear or the braze metal may be overheated. Joint geometry as well as electro-magnetic properties of the work piece...... presents a combined numerical and experimental method for determination of appropriate/optimiged coil geometry and position in induction brazing tube-to-plate joints of different ratios between tube and plate thickness and different combinations of the materials stainless steel, brass and copper....... The method has proven to give successful results in brazing tube-plate joints of copper-brass, copper-stainless steel, stainless steel-brass, and stainless steel-stainless steel. A new design of an adjustable flux concentrator for induction heating tube-to-plate joints is proposed and tested on a variety...

  18. Study on Application of New Approach of Fault Current Limiters in Fault Ride through Capability Improvement of DFIG Based Wind Turbine

    DEFF Research Database (Denmark)

    Naderi, Seyed Behzad; Davari, Pooya; Zhou, Dao

    2018-01-01

    Due to salient advantages, Doubly-Fed Induction Generator (DFIG) has more application in power network compared to Fixed Speed Wind Turbine. Because of employing back-to-back converters, one of the important studies regarding new grid code requirements is Fault Ride-Through (FRT) capability....... The proposed FCL can insert a controllable resistance in fault current pass to not only restrict fault current level and compensate voltage sag in the stator but also consume pre-fault output active power of the DFIG regarding wind speed variation. Simulation results and analytics are presented to prove...

  19. Illustration of Modern Wind Turbine Ancillary Services

    DEFF Research Database (Denmark)

    Margaris, Ioannis D.; Hansen, Anca Daniela; Sørensen, Poul Ejnar

    2010-01-01

    Increasing levels of wind power penetration in modern power systems has set intensively high standards with respect to wind turbine technology during the last years. Security issues have become rather critical and operation of wind farms as conventional power plants is becoming a necessity as wind...... turbines replace conventional units on the production side. This article includes a review of the basic control issues regarding the capability of the Doubly Fed Induction Generator (DFIG) wind turbine configuration to fulfill the basic technical requirements set by the system operators and contribute...

  20. Characterization and assessment of voltage and power constraints of DFIG WT connected to a weak network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Iov, Florin

    2014-01-01

    This article thoroughly investigates the challenges and constraints raised by the integration of a Doubly-fed Induction generator wind turbine, DFIG WT, into an ac network of extensively varying parameters and very weak conditions. The objective is to mitigate the voltage variations at the point...... of common coupling, PCC, and maximize the wind power penetration into weak networks. As a basis of investigation, a simplified system model is utilized and the respective PCC voltage, active and reactive power stability issues are identified. Besides, a steady-state study for DFIG WT connected to a weak...

  1. Comparison of Power Control Strategies for DFIG Wind Turbines

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Luna, A.; Rodríguez, P.

    2008-01-01

    The classical control techniques for regulating the active and reactive power delivery in doubly fed induction generators (DFIG), for wind power applications, are normally based on voltage oriented control (VOC) strategies. Among these algorithms, those that work in a synchronous reference frame...... VOC strategy able to control the operation of a DFIG in the αβ reference frame, with no need of flux position estimation, something that conducts to a more simple and robust algorithm. In order to evaluate the advantages of this new control proposal, namely VOC-RRF, their performance will be compared...

  2. Control Strategies for DFIG Wind Turbines Under Grid Fault

    DEFF Research Database (Denmark)

    Luna, Alvara; Rolan, A.; Medeiros, G.

    2009-01-01

    The classical control techniques for regulating the active and reactive power delivery in doubly fed induction generators (DFIG), for wind power applications, are normally based on voltage oriented control (VOC) strategies. Among these algorithms, those that work in a synchronous reference frame...... VOC strategy able to control the operation of a DFIG in the αβ reference frame, with no need of flux position estimation, something that conducts to a more simple and robust algorithm. In order to evaluate the advantages of this new control proposal, namely VOC-RRF, their performance will be compared...

  3. Design of power converter in DFIG wind turbine with enhanced system-level reliability

    DEFF Research Database (Denmark)

    Zhou, Dao; Zhang, Guanguan; Blaabjerg, Frede

    2017-01-01

    With the increasing penetration of wind power, reliable and cost-effective wind energy production are of more and more importance. As one of the promising configurations, the doubly-fed induction generator based partial-scale wind power converter is still dominating in the existing wind farms...... margin. It can be seen that the B1 lifetime of the grid-side converter and the rotor-side converter deviates a lot by considering the electrical stresses, while they become more balanced by using an optimized reliable design. The system-level lifetime significantly increases with an appropriate design...

  4. A Study of Wind Farm Stabilization Using DFIG or STATCOM Considering Grid Requirements

    Directory of Open Access Journals (Sweden)

    K. E Okedu

    2010-01-01

    Full Text Available Recently, the grid codes require taking into account the reactive power of the wind farm in order to contribute to the networkstability, thus operating the wind farm as active compensator devices. This paper presents a comparative study of stabilizinga wind farm using (Doubly Fed Induction Generators DFIGs or using a (Static Synchronous Compensator STATCOM duringwind speed change and grid fault. Simulation results show that the wind farm could be effectively stabilized with bothsystems, but at a reduced cost with the DFIGs system because it can provide reactive power through its frequency converterswithout an external reactive power compensation unit like the STATCOM system significant.

  5. Oscillatory Stability and Eigenvalue Sensitivity Analysis of A DFIG Wind Turbine System

    DEFF Research Database (Denmark)

    Yang, Lihui; Xu, Zhao; Østergaard, Jacob

    2011-01-01

    This paper focuses on modeling and oscillatory stability analysis of a wind turbine with doubly fed induction generator (DFIG). A detailed mathematical model of DFIG wind turbine with vector-control loops is developed, based on which the loci of the system Jacobian's eigenvalues have been analyzed......, showing that, without appropriate controller tuning a Hopf bifurcation can occur in such a system due to various factors, such as wind speed. Subsequently, eigenvalue sensitivity with respect to machine and control parameters is performed to assess their impacts on system stability. Moreover, the Hopf...

  6. Frequency Stability Enhancement for Low Inertia Systems using Synthetic Inertia of Wind Power

    DEFF Research Database (Denmark)

    Nguyen, Ha Thi; Yang, Guangya; Nielsen, Arne Hejde

    2017-01-01

    stability, this paper proposes supplementary control methods to implement synthetic inertia for doubly-fed induction generator (DFIG) based wind energy system during frequency excursions. Different control strategies and activation schemes are analyzed and implemented on the Western Danish renewable......-based system using-real time digital simulator (RTDS) to propose the best one for the synthetic inertia controller. From the comparative simulation results, it can be concluded that the method using a combination of both the frequency deviation and derivative as input signals, and the under-frequency trigger...

  7. Capability of DFIG WTS to ride through recurring asymmetrical grid faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Chen, Min

    2014-01-01

    The Wind Turbine Systems (WTS) are required to ride through recurring grid faults in some countries. In this paper, the capability of Doubly Fed Induction Generator (DFIG) WTS to ride through recurring asymmetrical grid faults is evaluated and compared with the ride through capability under single...... asymmetrical grid fault. A mathematical model of the DFIG under recurring asymmetrical grid faults is represented. The analysis are verified by simulations on a 1.5MW DFIG model and by experiments on a reduced-scale DFIG test system....

  8. Design of Nonlinear Robust Rotor Current Controller for DFIG Based on Terminal Sliding Mode Control and Extended State Observer

    Directory of Open Access Journals (Sweden)

    Guowei Cai

    2014-01-01

    Full Text Available As to strong nonlinearity of doubly fed induction generators (DFIG and uncertainty of its model, a novel rotor current controller with nonlinearity and robustness is proposed to enhance fault ride-though (FRT capacities of grid-connected DFIG. Firstly, the model error, external disturbances, and the uncertain factors were estimated by constructing extended state observer (ESO so as to achieve linearization model, which is compensated dynamically from nonlinear model. And then rotor current controller of DFIG is designed by using terminal sliding mode variable structure control theory (TSMC. The controller has superior dynamic performance and strong robustness. The simulation results show that the proposed control approach is effective.

  9. Flicker Mitigation of Grid Connected Wind Turbines Using STATCOM

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    to the point of common coupling (PCC) to relieve the flicker produced by grid connected wind turbines and the corresponding control scheme is described in detail. Simulation results show that STATCOM is an effective measure to mitigate the flicker level during continuous operation of grid connected wind......Grid connected wind turbines may produce flicker during continuous operation. In this paper flicker emission of grid connected wind turbines with doubly fed induction generators is investigated during continuous operation. A STATCOM using PWM voltage source converter (VSC) is connected in shunt...

  10. Induction technology optimization code

    International Nuclear Information System (INIS)

    Caporaso, G.J.; Brooks, A.L.; Kirbie, H.C.

    1992-01-01

    A code has been developed to evaluate relative costs of induction accelerator driver systems for relativistic klystrons. The code incorporates beam generation, transport and pulsed power system constraints to provide an integrated design tool. The code generates an injector/accelerator combination which satisfies the top level requirements and all system constraints once a small number of design choices have been specified (rise time of the injector voltage and aspect ratio of the ferrite induction cores, for example). The code calculates dimensions of accelerator mechanical assemblies and values of all electrical components. Cost factors for machined parts, raw materials and components are applied to yield a total system cost. These costs are then plotted as a function of the two design choices to enable selection of an optimum design based on various criteria. (Author) 11 refs., 3 figs

  11. Investigation of stability and x-ray spectrum in gas-puff z-pinch plasmas diriven by inductive energy storage pulsed power generator with a plasma opening switch

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, K.; Fukudome, I. [Yatsushiro National College of Technology, Dept. of Mechanical and Electrical Engineering, Yatsushiro, Kumamoto (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto Univ., Dept. of Electrical and Computer Engineering, Kumamoto (Japan)

    2002-06-01

    Gas-puff z-pinch plasmas are driven by an inductive voltage adder - inductive energy storage pulsed power generator ''ASO-X''. ASO-X has the performance of the maximum output voltage and current are 180 kV and 400 kA respectively and can provide a fast rise time current with operating POS. The stability of the plasma column, spectrum radiated from z-pinch plasmas and the spatial distribution of hot spots are investigated in the case with and without operating POS. By driving ASO-X with operating POS the kink instability is restrained and the stability of plasma column is improved about three times in regard to the average dispersion. Furthermore the duration of soft x-ray radiation is increased and the spatial distribution of hot spots is 50% improved with regard to kurtosis of the intensity profile of pinhole photographs compared to those without operating POS. (author)

  12. Investigation of stability and x-ray spectrum in gas-puff z-pinch plasmas diriven by inductive energy storage pulsed power generator with a plasma opening switch

    International Nuclear Information System (INIS)

    Murayama, K.; Fukudome, I.; Teramoto, Y.; Katsuki, S.; Akiyama, H.

    2002-01-01

    Gas-puff z-pinch plasmas are driven by an inductive voltage adder - inductive energy storage pulsed power generator ''ASO-X''. ASO-X has the performance of the maximum output voltage and current are 180 kV and 400 kA respectively and can provide a fast rise time current with operating POS. The stability of the plasma column, spectrum radiated from z-pinch plasmas and the spatial distribution of hot spots are investigated in the case with and without operating POS. By driving ASO-X with operating POS the kink instability is restrained and the stability of plasma column is improved about three times in regard to the average dispersion. Furthermore the duration of soft x-ray radiation is increased and the spatial distribution of hot spots is 50% improved with regard to kurtosis of the intensity profile of pinhole photographs compared to those without operating POS. (author)

  13. Development of hybrid frequency couplers for non-inductive current drive in a tokamak; Developpement de coupleurs a la frequence hybride pour la generation non inductive du courant dans un tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Berio, St.

    1996-11-04

    Used at its first time as an heating method in order to reach the temperature requisite for the fusion of a thermonuclear plasma, the hybrid waves has shown that they were the more efficient method for non-inductive current drive in a tokamak. The size and the objectives of a next machine such as ITER lead of the design of new antennae (in process of realisation on Tore Supra) made of oversized waveguides. This new concept of antenna will be more simple, more robust and will be able to transmit the same if not much power than the present antennae. This thesis contribute to the development of a new code called ALOHA (for `Advanced LOwer Hybrid Antenna`) which, at the end, will be able to give the characteristics and the behaviours of this new oversized antennae in front of a tokamak plasma. This thesis is also a first step in the interpretation of some experimental data concerning the measurement of coupling, absorption and current drive of the actual hybrid wave launched by a grill with rectangular waveguides. Moreover, this thesis lay some foundations of the study of these new antennae in front of a non-parallel confinement magnetic field and/or in front of poloidal inhomogeneities of plasma. (author). 53 refs.

  14. Overview of Bearingless Induction Motors

    Directory of Open Access Journals (Sweden)

    Xiaodong Sun

    2014-01-01

    Full Text Available Bearingless induction motors combining functions of both torque generation and noncontact magnetic suspension together have attracted more and more attention in the past decades due to their definite advantages of compactness, simple structure, less maintenance, no wear particles, high rotational speed, and so forth. This paper overviews the key technologies of the bearingless induction motors, with emphasis on motor topologies, mathematical models, and control strategies. Particularly, in the control issues, the vector control, independent control, direct torque control, nonlinear decoupling control, sensorless control, and so forth are investigated. In addition, several possible development trends of the bearingless induction motors are also discussed.

  15. Diagnostics for induction accelerators

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1996-04-01

    The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960's to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore's Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail

  16. Diagnostics for induction accelerators

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1997-01-01

    The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at Lawrence Livermore National Laboratory (LLNL) from the early 1960s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400-ns pulses. The Advanced Test Accelerator (ATA) built at Livermore close-quote s Site 300 produced 10,000-Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and Lawrence Berkeley National Laboratory (LBNL). This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high-current, short-pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail. copyright 1997 American Institute of Physics

  17. The effect of X-irradiation on the fertility and on the induction of meiotic chromosome rearrangements in mice and their first generation

    International Nuclear Information System (INIS)

    Savkovic, N.; Pecevski, J.; Maric, N.; Radivojevic, D.

    1980-01-01

    The effect of whole-body or local irradiation with X-rays at a dose of 600 R on the induction of chromosomal translocations in the diakinesis metaphase I of the meiosis in treated and F 1 males has been examined along with their fertility. Our results show the high percentage of mortality in whole-body irradiated mice. The percentage of the fertility was 25% in whole-body, and 93.7% in locally irradiated males. The testis weight was also reduced. The percentage of chromosomal translocations in diakinesis, metaphase I, of the meiosis was higher after whole-body irradiation than after local irradiation. In F 1 males both types of irradiation induced chromosomal translocations. (orig.) [de

  18. The effect of X-irradiation on the fertility and the induction of meiotic chromosome rearrangements in mice and their first generation

    International Nuclear Information System (INIS)

    Savkovic, N.; Pecevski, J.; Maric, N.; Radivojevic, D.

    1978-01-01

    The effect of whole-body and local irradiation with a dose of 600 X-rays on the induction of chromosomal translocations in Diakinesis-Metaphase I of meiosis in treated and F 1 males and their fertility have been examined. Our results showed the high percentage of mortality in whole-body irradiated mice. The percentage of fertility was 25% in whole-body, and 93,7% in locally irradiated males. The testis weight was also reduced. The percentage of chromosomal translocations in Diakinesis-Metaphase I of meiosis was greater after whole-body than after local irradiation. In F 1 males both types of irradiation induced chromosomal translocations. (orig.) [de

  19. Development of a module combustor biomass-motor Stirling applied to a isolated generation system and based on induction generator; Desenvolvimento de um modulo combustor biomassa-motor Stirling aplicado a sistemas de geracao isolada e baseados em gerador de inducao

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Humberto; Lora, Electo Eduardo Silva [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Nucleo de Excelencia em Geracao Termeletrica e Distribuida

    2004-07-01

    In some areas in Brazil the great distance of the generating and consuming centers, together with the low consumption of electric energy of these areas, they make unfeasible investments with transmission and distribution. The use of the biomass as fuel in the distributed generation, is low pollutions, it is renewable, besides possessing a low cost when compared to the fossil fuels [Barros, 2003]. By the way the generation distributed through renewable fuels, becomes an attractive solution for generation in distant and isolated areas of the electric system. Inside of this context, this paper proposes the use of a module combustor, biomass-motor Stirling, based on induction generator, applied to isolated areas, such as the north and northeast areas of the Brazil. (author)

  20. Reactive power control of wind farm using facts devices

    International Nuclear Information System (INIS)

    Ashfaq, S.; Arif, A.; Shakeel, A.; Mahmood, T.

    2014-01-01

    Wind energy is an attainable option to complement other types of pollution-free green generation Grid connections of renewable energy resources are vital if they are to be effectively exploited, but grid connection brings problems of voltage fluctuation and harmonic distortion. FACTs devices are one of the power electronics revolutions to improve voltage profile, system stability, and reactive power control and to reduce transmission losses. The studied system here is a variable speed wind generation system based on Induction Generator (IG) with integration of different FACTs controllers in the wind farm. To harness the wind power efficiently the most reliable and expensive system in the present era is grid connected doubly fed induction generator. Induction generator with FACTs devices is a suitable economical replacement. The suggested scheme is implemented in MATLAB Simulink with real time parameters of GHARO wind power plant in Sind, and corresponding results and output waveforms proves the potential strength of proposed methodology. (author)

  1. FACTS for grid integration of large offshore wind farms by means of AC

    Energy Technology Data Exchange (ETDEWEB)

    Gruenbaum, Rolf; Halvarsson, Per

    2007-07-01

    The dominating kind of wind power is asynchronous, this since it is robust and cost effective. Induction generators, however, do not contribute to regulation of grid voltage, and they are substantial absorbers of reactive power. The reactive power balance of asynchronous generators can be improved to a certain extent by use of the doubly-fed rotor concept. To keep this technology within reasonable cost margins, however, rotor converter ratings must be kept limited to steady-state requirements only. During transient occurrencies in the grid, the performance of doubly-fed induction generators (DFIG) may well prove inadequate to safeguard primarily voltage stability of the grid. Here, dynamic reactive power compensation plays an important role in supporting DFIG. FACTS applied at the grid connection point can support the voltage during steady-state conditions as well as upon clearing of grid faults. The utilization of SVC and STATCOM for these purposes are discussed in in the paper. Furthermore, energy storage devices are treated, as a coming means for improving active power balance in grids fed by wind power. (auth)

  2. Irradiation of rainbow trout at early life stages results in trans-generational effects including the induction of a bystander effect in non-irradiated fish.

    Science.gov (United States)

    Smith, Richard W; Seymour, Colin B; Moccia, Richard D; Mothersill, Carmel E

    2016-02-01

    The bystander effect, a non-targeted effect (NTE) of radiation, which describes the response by non-irradiated organisms to signals emitted by irradiated organisms, has been documented in a number of fish species. However transgenerational effects of radiation (including NTE) have yet to be studied in fish. Therefore rainbow trout, which were irradiated as eggs at 48h after fertilisation, eyed eggs, yolk sac larvae or first feeders, were bred to generate a F1 generation and these F1 fish were bred to generate a F2 generation. F1 and F2 fish were swam with non-irradiated bystander fish. Media from explants of F1 eyed eggs, F1 one year old fish gill and F1 two year old fish gill and spleen samples, and F2 two year old gill and spleen samples, as well as from bystander eggs/fish, was used to treat a reporter cell line, which was then assayed for changes in cellular survival/growth. The results were complex and dependent on irradiation history, age (in the case of the F1 generation), and were tissue specific. For example, irradiation of one parent often resulted in effects not seen with irradiation of both parents. This suggests that, unlike mammals, in certain circumstances maternal and paternal irradiation may be equally important. This study also showed that trout can induce a bystander effect 2 generations after irradiation, which further emphasises the importance of the bystander effect in aquatic radiobiology. Given the complex community structure in aquatic ecosystems, these results may have significant implications for environmental radiological protection. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Irradiation of rainbow trout at early life stages results in trans-generational effects including the induction of a bystander effect in non-irradiated fish

    International Nuclear Information System (INIS)

    Smith, Richard W.; Seymour, Colin B.; Moccia, Richard D.; Mothersill, Carmel E.

    2016-01-01

    The bystander effect, a non-targeted effect (NTE) of radiation, which describes the response by non-irradiated organisms to signals emitted by irradiated organisms, has been documented in a number of fish species. However transgenerational effects of radiation (including NTE) have yet to be studied in fish. Therefore rainbow trout, which were irradiated as eggs at 48 h after fertilisation, eyed eggs, yolk sac larvae or first feeders, were bred to generate a F1 generation and these F1 fish were bred to generate a F2 generation. F1 and F2 fish were swam with non-irradiated bystander fish. Media from explants of F1 eyed eggs, F1 one year old fish gill and F1 two year old fish gill and spleen samples, and F2 two year old gill and spleen samples, as well as from bystander eggs/fish, was used to treat a reporter cell line, which was then assayed for changes in cellular survival/growth. The results were complex and dependent on irradiation history, age (in the case of the F1 generation), and were tissue specific. For example, irradiation of one parent often resulted in effects not seen with irradiation of both parents. This suggests that, unlike mammals, in certain circumstances maternal and paternal irradiation may be equally important. This study also showed that trout can induce a bystander effect 2 generations after irradiation, which further emphasises the importance of the bystander effect in aquatic radiobiology. Given the complex community structure in aquatic ecosystems, these results may have significant implications for environmental radiological protection. - Highlights: • We evaluated the transgenerational effect of early life irradiation in rainbow trout. • Trout irradiated as eggs, yolk sac larvae or first feeders were crossed. • A transgenerational effect was evident in two generations after irradiation. • F1 and F2 generation fish induced a bystander effect in non-irradiated fish. • The precise effects were tissue specific and dependent on

  4. Irradiation of rainbow trout at early life stages results in trans-generational effects including the induction of a bystander effect in non-irradiated fish

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Richard W., E-mail: rich.wilson.smith@gmail.com [Department of Animal Biosciences, University of Guelph, Guelph, Ontario (Canada); Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario (Canada); Seymour, Colin B. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario (Canada); Moccia, Richard D. [Department of Animal Biosciences, University of Guelph, Guelph, Ontario (Canada); Mothersill, Carmel E. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario (Canada)

    2016-02-15

    The bystander effect, a non-targeted effect (NTE) of radiation, which describes the response by non-irradiated organisms to signals emitted by irradiated organisms, has been documented in a number of fish species. However transgenerational effects of radiation (including NTE) have yet to be studied in fish. Therefore rainbow trout, which were irradiated as eggs at 48 h after fertilisation, eyed eggs, yolk sac larvae or first feeders, were bred to generate a F1 generation and these F1 fish were bred to generate a F2 generation. F1 and F2 fish were swam with non-irradiated bystander fish. Media from explants of F1 eyed eggs, F1 one year old fish gill and F1 two year old fish gill and spleen samples, and F2 two year old gill and spleen samples, as well as from bystander eggs/fish, was used to treat a reporter cell line, which was then assayed for changes in cellular survival/growth. The results were complex and dependent on irradiation history, age (in the case of the F1 generation), and were tissue specific. For example, irradiation of one parent often resulted in effects not seen with irradiation of both parents. This suggests that, unlike mammals, in certain circumstances maternal and paternal irradiation may be equally important. This study also showed that trout can induce a bystander effect 2 generations after irradiation, which further emphasises the importance of the bystander effect in aquatic radiobiology. Given the complex community structure in aquatic ecosystems, these results may have significant implications for environmental radiological protection. - Highlights: • We evaluated the transgenerational effect of early life irradiation in rainbow trout. • Trout irradiated as eggs, yolk sac larvae or first feeders were crossed. • A transgenerational effect was evident in two generations after irradiation. • F1 and F2 generation fish induced a bystander effect in non-irradiated fish. • The precise effects were tissue specific and dependent on

  5. Model for Investigation of Operational Wind Power Plant Regimes with Doubly–Fed Asynchronous Machine in Power System

    Directory of Open Access Journals (Sweden)

    R. I. Mustafayev

    2012-01-01

    Full Text Available The paper presents methodology for mathematical modeling of power system (its part when jointly operated with wind power plants (stations that contain asynchronous doubly-fed machines used as generators. The essence and advantage of the methodology is that it allows efficiently to mate equations of doubly-fed asynchronous machines, written in the axes that rotate with the machine rotor speed with the equations of external electric power system, written in synchronously rotating axes.

  6. A Hybrid Fault-Tolerant Strategy for Severe Sensor Failure Scenarios in Late-Stage Offshore DFIG-WT

    Directory of Open Access Journals (Sweden)

    Wei Li

    2017-12-01

    Full Text Available As the phase current sensors and rotor speed/position sensor are prone to fail in the late stage of an offshore doubly-fed induction generator based wind turbine (DFIG-WT, this paper investigates a hybrid fault-tolerant strategy for a severe sensor failure scenario. The phase current sensors in the back-to-back (BTB converter and the speed/position sensor are in the faulty states simultaneously. Based on the 7th-order doubly-fed induction generator (DFIG dynamic state space model, the extended Kalman filter (EKF algorithm is applied for rotor speed and position estimation. In addition, good robustness of this sensorless control algorithm to system uncertainties and measurement disturbances is presented. Besides, a single DC-link current sensor based phase current reconstruction scheme is utilized for deriving the phase current information according to the switching states. A duty ratio adjustment strategy is proposed to avoid missing the sampling points in a switching period, which is simple to implement. Furthermore, the additional active time of the targeted nonzero switching states is complemented so that the reference voltage vector remains in the same position as that before duty ratio adjustment. The validity of the proposed hybrid fault-tolerant sensorless control strategy is demonstrated by simulation results in Matlab/Simulink2017a by considering harsh operating environments.

  7. Study of the non inductive current generation in Tore Supra and application to the operational scenario of a continuous tokamak; Etude de la generation de courant non inductive dans Tore Supra et application aux scenarios operationnels d`un tokamak continu

    Energy Technology Data Exchange (ETDEWEB)

    Kazarian-Vibert, F.

    1996-07-05

    Lower Hybrid Current Drive in tokamak plasmas allows to obtain continuous operations, which constitute a necessary step towards a definition of a thermonuclear fusion reactor. The objectives of this work is to define and study fully non inductive steady-state scenarios on Tore Supra. The current diffusion equation is solved to determined precisely the inductive and non inductive current density profiles and their influence on thee time evolution of a discharge. Then, a new operation mode is studied theoretically and experimentally. In this scenario, the transformer primary circuit voltage is controlled in such a way that the flux consumption vanishes. It allows to achieve full steady-state discharges in a fast and reproducible manner. A theoretical flux consumption scaling law during plasma current ramp-up assisted by Lower-Hybrid waves is presented and validated by experimental data, in view to minimized this consumption. The influence of a non monotonic current profile on the confinement and the transport of energy in the plasma is also clearly illustrated by experiments. (author). 138 refs., 16 figs., 1 tab.

  8. Performance Analysis of a Flywheel Energy Storage System

    Directory of Open Access Journals (Sweden)

    K. Ghedamsi

    2008-06-01

    Full Text Available The flywheel energy storage systems (FESSs are suitable for improving the quality of the electric power delivered by the wind generators and to help these generators to contribute to the ancillary services. In this paper, a flywheel energy storage system associated to a grid connected variable speed wind generation (VSWG scheme using a doubly fed induction generator (DFIG is investigated. Therefore, the dynamic behavior of a wind generator, including models of the wind turbine (aerodynamic, DFIG, matrix converter, converter control (algorithm of VENTURINI and power control is studied. This paper investigates also, the control method of the FESS with a classical squirrel-cage induction machine associated to a VSWG using back-to-back AC/AC converter. Simulation results of the dynamic models of the wind generator are presented, for different operating points, to show the good performance of the proposed system.

  9. d -Limonene sensitizes docetaxel-induced cytotoxicity in human prostate cancer cells: Generation of reactive oxygen species and induction of apoptosis

    Directory of Open Access Journals (Sweden)

    Rabi Thangaiyan

    2009-01-01

    Full Text Available Background: Clinical trials have shown that docetaxel combined with other novel agents can improve the survival of androgen-independent prostate cancer patients. d -Limonene, a non-nutrient dietary component, has been found to inhibit various cancer cell growths without toxicity. We sought to characterize whether a non-toxic dose of d -limonene may enhance tumor response to docetaxel in an in vitro model of metastatic prostate cancer. Materials and Methods: Human prostate carcinoma DU-145 and normal prostate epithelial PZ-HPV-7 cells were treated with various concentrations of d -limonene, docetaxel or a combination of both, and cell viability was determined by MTT assay. Intracellular reactive oxygen species (ROS, reduced glutathione (GSH and caspase activity were measured. Apoptosis and apoptosis-related proteins were studied by enzyme-linked immunosorbent assay and Western blotting, respectively. Results: d -Limonene and docetaxel in combination significantly enhanced the cytotoxicity to DU-145 cells than PZ-HPV-7 cells. Exposure of DU-145 cells to a combined d -limonene and docetaxel resulted in higher ROS generation, depletion of GSH, accompanied by increased caspase activity than docetaxel alone. It also triggered a series of effects involving cytochrome c , cleavages of caspase-9, 3 and poly (ADP-ribose polymerase, and a shift in Bad:Bcl-xL ratio in favor of apoptosis. Apoptotic effect was significantly blocked on pretreatment with N -acetylcystein, indicating that antitumor effect is initiated by ROS generation, and caspase cascades contribute to the cell death. Conclusion: Our results show, for the first time, that d -limonene enhanced the antitumor effect of docetaxel against prostate cancer cells without being toxic to normal prostate epithelial cells. The combined beneficial effect could be through the modulation of proteins involved in mitochondrial pathway of apoptosis. d -Limonene could be used as a potent non-toxic agent to

  10. New type of magnetohydrodynamic converters: induction devices

    International Nuclear Information System (INIS)

    Petit, J.-P.; Viton, Maurice.

    1977-01-01

    A new induction MHD accelerator, disc shaped, with controlled ionization, is presented. Associated with a light and powerful electric generator it could become a MHD aerodyne. Solutions for confining the plasma to the wall are indicated [fr

  11. Impact of wind power in autonomous power systems—power fluctuations—modelling and control issues

    DEFF Research Database (Denmark)

    Margaris, Ioannis D.; Hansen, Anca Daniela; Cutululis, Nicolaos Antonio

    2011-01-01

    for diesel and steam generation plants are applied. The power grid, including speed governors, automatic voltage regulators, protection system and loads is modelled in the same platform. Results for different load and wind profile cases are being presented for the case study of the island Rhodes, in Greece......This paper describes a detailed modelling approach to study the impact of wind power fluctuations on the frequency control in a non-interconnected system with large-scale wind power. The approach includes models for wind speed fluctuations, wind farm technologies, conventional generation...... technologies, power system protection and load. Analytical models for wind farms with three different wind turbine technologies, namely Doubly Fed Induction Generator, Permanent Magnet Synchronous Generator and Active Stall Induction Generator-based wind turbines, are included. Likewise, analytical models...

  12. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  13. The effectiveness of laser diode induction to Carica Papaya L. chlorophyll extract to be ROS generating in the photodynamic inactivation mechanisms for C.albicans biofilms

    International Nuclear Information System (INIS)

    Astuty, S Dewi; Baktir, A

    2017-01-01

    Research on the effectiveness of photo inactivation of C.albicans biofilms led by a-PDT system mediated by chlorophyll-diode-laser-induced was done. This research was done using in vitro technique in order to effectively determine chlorophyll extract of ROS-generated Carica Papaya L. using in situ technique. This technique induced laser diode on different dose and C. albicans with reduced degree. This research is a preliminary study in efforts to find anew sensitizer agent candidate made of chlorophyll extract and antifungal of Carica Papaya L. The effectiveness of eradication has been tested with MDA’s content and OD of biomass biofilms as well as analyzed using ANOVA and Tukey Test (α=0.05). The characteristic of chlorophyll extract of Carica Papaya L. has maximum absorptions on blue areas (λ max = 420 nm) and red areas (λ max = 670 nm). The MIC value of Carica Papaya L. ’s chlorophyll extract against C. albicans planktonic and biofilms cell is 63.8 μM and 31.9 μM respectively. The result shows that treatment using laser which was combined with chlorophyll extract is more effective than that with laser only or chlorophyll extract only. The treatment using laser combined with chlorophyll extract obtained more than 65% (α=0.05) (more than that of negative control) for P 2 L 1 group with OD 595 0.915. The MDA’s content showed that group of laser which was mediated with chlorophyll extract had larger values than group of laser or chlorophyll extract only. (paper)

  14. Model predictive control of wind energy conversion systems

    CERN Document Server

    Yaramasu, Venkata Narasimha R

    2017-01-01

    The authors provide a comprehensive analysis on the model predictive control of power converters employed in a wide variety of variable-speed wind energy conversion systems (WECS). The contents of this book includes an overview of wind energy system configurations, power converters for variable-speed WECS, digital control techniques, MPC, modeling of power converters and wind generators for MPC design. Other topics include the mapping of continuous-time models to discrete-time models by various exact, approximate, and quasi-exact discretization methods, modeling and control of wind turbine grid-side two-level and multilevel voltage source converters. The authors also focus on the MPC of several power converter configurations for full variable-speed permanent magnet synchronous generator based WECS, squirrel-cage induction generator based WECS, and semi-variable-speed doubly fed induction generator based WECS.

  15. Borehole induction coil transmitter

    Science.gov (United States)

    Holladay, Gale; Wilt, Michael J.

    2002-01-01

    A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

  16. Project PAT (Pumps Working as Turbines)/IG (Induction Generators): a new concept for generation of electric power through micro scale hydroelectric power plants; Projeto BFT (Bombas Funcionado como Turbinas)/GI (Geradores de Inducao): um novo conceito para geracao de energia eletrica atraves de microcentrais hidreletricas

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Augusto Nelson Carvalho [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Inst. de Recursos Naturais. Programa de Pos-graduacao em Engenharia da Energia; Medeiros, Daniel de Macedo; Ricardo, Mateus [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Inst. de Recursos Naturais], Emails: augusto@unifei.edu.br, macedo@unifei.edu.br, mathidr@yahoo.com.br

    2006-07-01

    The present work has as objective to present the main bases of 'PAT/IG Project', accomplished in Boa Esperanca Farm (Delfim Moreira - MG), by an accord between Itajuba's Federal University and Mines and Energy Ministry. In a moment that the look for sustainable development is the law in Brazil, low costs and environmental impact alternatives must be prioritized. By this way, the PAT/IG Project continuous the Viana's (1987) works, that developed all Brazilian theoretical bases for using Pumps Working as Turbine (PAT). Besides that, the application of induction motors operating as induction generators will be evaluated, as the velocity control system of the PAT/IG group will be developed. The existing Boa Esperanca Farm's micro power plant will be rebuild ed, to receive a new generating group formed for a PAT and a IG, that will be used as natural sized test workbench of Itajuba's Federal University. At the ending of the project, there will be enough subsidies to prove, in practice, the feasibility presented in laboratorial tests by PAT/IG groups as conventional turbines replacer in micro powerplants. (author)

  17. Project PAT (Pumps Working as Turbines)/IG (Induction Generators): a new concept for generation of electric power through micro scale hydroelectric power plants; Projeto BFT (Bombas Funcionado como Turbinas)/GI (Geradores de Inducao): um novo conceito para geracao de energia eletrica atraves de microcentrais hidreletricas

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Augusto Nelson Carvalho [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Inst. de Recursos Naturais. Programa de Pos-graduacao em Engenharia da Energia; Medeiros, Daniel de Macedo; Ricardo, Mateus [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Inst. de Recursos Naturais], Emails: augusto@unifei.edu.br, macedo@unifei.edu.br, mathidr@yahoo.com.br

    2006-07-01

    The present work has as objective to present the main bases of 'PAT/IG Project', accomplished in Boa Esperanca Farm (Delfim Moreira - MG), by an accord between Itajuba's Federal University and Mines and Energy Ministry. In a moment that the look for sustainable development is the law in Brazil, low costs and environmental impact alternatives must be prioritized. By this way, the PAT/IG Project continuous the Viana's (1987) works, that developed all Brazilian theoretical bases for using Pumps Working as Turbine (PAT). Besides that, the application of induction motors operating as induction generators will be evaluated, as the velocity control system of the PAT/IG group will be developed. The existing Boa Esperanca Farm's micro power plant will be rebuild ed, to receive a new generating group formed for a PAT and a IG, that will be used as natural sized test workbench of Itajuba's Federal University. At the ending of the project, there will be enough subsidies to prove, in practice, the feasibility presented in laboratorial tests by PAT/IG groups as conventional turbines replacer in micro powerplants. (author)

  18. Inductive Monitoring System (IMS)

    Data.gov (United States)

    National Aeronautics and Space Administration — IMS: Inductive Monitoring System The Inductive Monitoring System (IMS) is a tool that uses a data mining technique called clustering to extract models of normal...

  19. Inductive Reasoning and Writing

    Science.gov (United States)

    Rooks, Clay; Boyd, Robert

    2003-01-01

    Induction, properly understood, is not merely a game, nor is it a gimmick, nor is it an artificial way of explaining an element of reasoning. Proper understanding of inductive reasoning--and the various types of reasoning that the authors term inductive--enables the student to evaluate critically other people's writing and enhances the composition…

  20. Two Level Versus Matrix Converters Performance in Wind Energy Conversion Systems Employing DFIG

    Science.gov (United States)

    Reddy, Gongati Pandu Ranga; Kumar, M. Vijaya

    2017-10-01

    Wind power capacity has received enormous growth during past decades. With substantial development of wind power, it is expected to provide a fifth of world's electricity by the end of 2030. In wind energy conversion system, the power electronic converters play an important role. This paper presents the two level and matrix converters performance in wind energy conversion system employing Doubly Fed Induction Generator (DFIG). The DFIG is a wound rotor induction generator. Because of the advantages of the DFIG over other generators it is being used for most of the wind applications. This paper also discusses control of converters using the space vector pulse width modulation technique. The MATLAB/SIMULINK ® software is used to study the performance of the converters.

  1. The law of electromagnetic induction

    Directory of Open Access Journals (Sweden)

    V.J. Kutkovetskyy

    2014-09-01

    Full Text Available Mathematical models of the electromagnetic induction law which do not take into account Faraday’s restrictions are not in full accordance with the physical phenomenon and so they are not laws. Their incomplete correspondence with real devices results in such "paradoxes" as unlimited magnetic field of unipolar generators, infinite sizes of inductors for DC and AC machines modeled, and so on.

  2. Induction machine handbook

    CERN Document Server

    Boldea, Ion

    2002-01-01

    Often called the workhorse of industry, the advent of power electronics and advances in digital control are transforming the induction motor into the racehorse of industrial motion control. Now, the classic texts on induction machines are nearly three decades old, while more recent books on electric motors lack the necessary depth and detail on induction machines.The Induction Machine Handbook fills industry's long-standing need for a comprehensive treatise embracing the many intricate facets of induction machine analysis and design. Moving gradually from simple to complex and from standard to

  3. Efficient generation of volatile cadmium species using Ti(III) and Ti(IV) and application to determination of cadmium by cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS)†

    Science.gov (United States)

    Arslan, Zikri; Yilmaz, Vedat; Rose, LaKeysha

    2015-01-01

    In this study, a highly efficient chemical vapor generation (CVG) approach is reported for determination of cadmium (Cd). Titanium (III) and titanium (IV) were investigated for the first time as catalytic additives along with thiourea, L-cysteine and potassium cyanide (KCN) for generation of volatile Cd species. Both Ti(III) and Ti(IV) provided the highest enhancement with KCN. The improvement with thiourea was marginal (ca. 2-fold), while L-cysteine enhanced signal slightly only with Ti(III) in H2SO4. Optimum CVG conditions were 4% (v/v) HCl + 0.03 M Ti(III) + 0.16 M KCN and 2% (v/v) HNO3 + 0.03 M Ti(IV) + 0.16 M KCN with a 3% (m/v) NaBH4 solution. The sensitivity was improved about 40-fold with Ti(III) and 35-fold with Ti(IV). A limit of detection (LOD) of 3.2 ng L−1 was achieved with Ti(III) by CVG-ICP-MS. The LOD with Ti(IV) was 6.4 ng L−1 which was limited by the blank signals in Ti(IV) solution. Experimental evidence indicated that Ti(III) and Ti(IV) enhanced Cd vapor generation catalytically; for best efficiency mixing prior to reaction with NaBH4 was critical. The method was highly robust against the effects of transition metal ions. No significant suppression was observed in the presence of Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II) up to 1.0 μg mL−1. Among the hydride forming elements, no interference was observed from As(III) and Se(IV) at 0.5 μg mL−1 level. The depressive effects from Pb(II) and Sb(III) were not significant at 0.1 μg mL−1 while those from Bi(III) and Sn(II) were marginal. The procedures were validated with determination of Cd by CVG-ICP-MS in a number certified reference materials, including Nearshore seawater (CASS-4), Bone ash (SRM 1400), Dogfish liver (DOLT-4), Mussel tissue (SRM 2976) and Domestic Sludge (SRM 2781). PMID:26251554

  4. 风能

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [篇名] A case study on energy saving and new energy services in Japan, [篇名] A linear dynamic model for asynchronous wind turbines with mechanical fluctuations, [篇名] A method of tracking the peak power points for a variable speed wind energy conversion system, [篇名] A new model for short-term wind electric power forecasting, [篇名] A new simulation platform to model, optimize and design wind turbines, [篇名 ] A New Vertical Axis Wind Rotor using Convergent Nozzles, [ 篇名 ] A Novel Doubly-fed Induction Wind Generato Control Scheme for Reactive Power Control and Torque Pulsation Compensation Under Unbalanced Grid Voltage Conditions, [ 篇名 ] A review on recent advances on wind energy system, [ 篇名 ] A Sensorless Integrated Doubly-Fed Electric Alternator/Active Filter (IDEA) for Variable Speed Wind Energy System, [ 篇名 ] A Simple Maximum Power Point Tracker for Grid connected Variablc Spccd Wind Energy Convcrsion System with Reduced Switch Count Power Converters, [ 篇名] A STOCHASTIC MARKOV CHAIN MODEL FOR SIMULATING WIND SPEED TIME SERIES at Tangiers, MOROCCO, [ 篇名 ] A switched reluctance wind power generator with the excitation of low voltage, [篇名] A technology assessment system of the alternative energy sources (sun and wind) for rural communities in Mexico, [ 篇名 ] A virtual instrument for automatic anemometer calibration with ANN based supervision.

  5. High performance fuzzy sliding mode control of DFIG supplied by seven level NPC inverter

    Directory of Open Access Journals (Sweden)

    Mohamed BENKAHLA

    2017-09-01

    Full Text Available This article presents the powers control of a variable speed wind turbine (WT based on a doubly fed induction generator (DFIG because of their advantages in terms of economy and control. The considered system consists of a double fed induction generator whose stator is connected directly to the network and its rotor is supplied by seven-level inverter with structure NPC are well used to minimize the harmonics absorbed by the DFIG. In order to control the power flowing between the stator of the DFIG and the grid. Have been studied and compared two types of controllers : Sliding Mode Control (SMC and Fuzzy SMC (FSMC. Their respective performances are compared in terms of power reference tracking, response to sudden speed variations, sensitivity to perturbations and robustness against machine parameters variations.

  6. Voltage stability issues for a benchmark grid model including large scale wind power

    DEFF Research Database (Denmark)

    Eek, J.; Lund, T.; Marzio, G. Di

    2006-01-01

    The objective of the paper is to investigate how the voltage stability of a relatively weak network after a grid fault is affected by the connection of a large wind park. A theoretical discussion of the stationary and dynamic characteristics of the Short Circuit Induction Generator and the Doubly...... Fed Induction Generator is given. Further, a case study of a wind park connected to the transmission system through an existing regional 132 kV regional distribution line is presented. For the SCIG it is concluded that a stationary torque curve calculated under consideration of the impedance...... of the network and saturation of the external reactive power compensation units provides a good basis for evaluation of the voltage stability. For the DFIG it is concluded that the speed stability limit is mainly determined by the voltage limitation of the rotor converter...

  7. Flow injection electrochemical hydride generation inductively coupled plasma time-of-flight mass spectrometry for the simultaneous determination of hydride forming elements and its application to the analysis of fresh water samples

    International Nuclear Information System (INIS)

    Bings, Nicolas H.; Stefanka, Zsolt; Mallada, Sergio Rodriguez

    2003-01-01

    A flow injection (FI) method was developed using electrochemical hydride generation (EcHG) as a sample introduction system, coupled to an inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) for rapid and simultaneous determination of six elements forming hydrides (As, Bi, Ge, Hg, Sb and Se). A novel low volume electrolysis cell, especially suited for FI experiments was designed and the conditions for simultaneous electrochemical hydride generation (EcHG; electrolyte concentrations and flow rates, electrolysis voltage and current) as well as the ICP-TOFMS operational parameters (carrier gas flow rate, modulation pulse width (MPW)) for the simultaneous determination of 12 isotopes were optimized. The compromise operation parameters of the electrolysis were found to be 1.4 and 3 ml min -1 for the anolyte and catholyte flow rates, respectively, using 2 M sulphuric acid. An optimum electrolysis current of 0.7 A (16 V) and an argon carrier gas flow rate of 0.91 l min -1 were chosen. A modulation pulse width of 5 μs, which influences the sensitivity through the amount of ions being collected by the MS per single analytical cycle, provided optimum results for the detection of transient signals. The achieved detection limits were compared with those obtained by using FI in combination with conventional nebulization (FI-ICP-TOFMS); values for chemical hydride generation (FI-CHG-ICP-TOFMS) were taken from the literature. By using a 200 μl sample loop absolute detection limits (3σ) in the range of 10-160 pg for As, Bi, Ge, Hg, Sb and 1.1 ng for Se and a precision of 4-8% for seven replicate injections of 20-100 ng ml -1 multielemental sample solutions were achieved. The analysis of a standard reference material (SRM) 1643d (NIST, 'Trace Elements in Water') showed good agreement with the certified values for As and Sb. Se showed a drastic difference, which is probably due to the presence of hydride-inactive Se species in the sample. Recoveries better than

  8. Understanding the effects of potassium ferricyanide on lead hydride formation in tetrahydroborate system and its application for determination of lead in milk using hydride generation inductively coupled plasma optical emission spectrometry

    International Nuclear Information System (INIS)

    Deng, Biyang; Xu, Xiangshu; Xiao, Yan; Zhu, Pingchuan; Wang, Yingzi

    2015-01-01

    Highlights: • Proposed a novel explanation for plumbane generation. • Expounded the role of K 3 Fe(CN) 6 in plumbane generation. • Clarified the controversial aspects in the mechanism of K 3 Fe(CN) 6 enhancement. • Used X-ray diffractometry to analyze the intermediates. • Developed a method to analyze lead in milk using K 3 Fe(CN) 6 and K 4 Fe(CN) 6 as new additives. - Absract: To understand the formation of plumbane in the Pb II -NaBH 4 -K 3 Fe(CN) 6 system, the intermediate products produced in the reaction of lead(II) and NaBH 4 in the presence of K 3 Fe(CN) 6 were studied. The produced plumbane and elemental lead were measured through continuous flow hydride generation (HG)-inductively coupled plasma optical emission spectrometry (ICP OES) and X-ray diffraction spectrometry techniques, respectively. Based on the experimental results, the explanations can be depicted in the following steps: (1) plumbane and black lead sediment (black Pb) are formed in the reaction of lead(II) and NaBH 4 ; (2) the black Pb is oxidized by K 3 Fe(CN) 6 to form Pb 2 [Fe(CN) 6 ], which further reacts with NaBH 4 to form more plumbane and black Pb; and (3) another round starts in which the produced black Pb from the step 2 is then oxidized continuously by K 3 Fe(CN) 6 to form more Pb 2 [Fe(CN) 6 ] complex, which would produce more plumbane. In short, the black Pb and Pb 2 [Fe(CN) 6 ] complex are the key intermediate products for the formation of plumbane in the Pb II -NaBH 4 -K 3 Fe(CN) 6 system. Based on the enhancement effect of potassium ferricyanide and potassium ferrocyanide, a method was developed to analyze lead in milk with HG-ICP OES technique. The detection limit of the method was observed as 0.081 μg L −1 . The linearity range of lead was found between 0.3 and 50,000 μg L −1 with correlation coefficient of 0.9993. The recovery of lead was determined as 97.6% (n = 5) for adding 10 μg L −1 lead into the milk sample

  9. Urofollitropin and ovulation induction

    NARCIS (Netherlands)

    van Wely, Madelon; Yding Andersen, Claus; Bayram, Neriman; van der Veen, Fulco

    2005-01-01

    Anovulation is a common cause of female infertility. Treatment for women with anovulation is aimed at induction of ovulation. Ovulation induction with follicle-stimulating hormone (FSH) is indicated in women with WHO type II anovulation in whom treatment with clomifene citrate (clomifene) has

  10. Inductance loop and partial

    CERN Document Server

    Paul, Clayton R

    2010-01-01

    "Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

  11. Real-time integration of control strategies for an isolated DFIG-based WECS

    Science.gov (United States)

    Bouchiba, Nouha; Barkia, Asma; Chrifi-Alaoui, Larbi; Drid, Saïd; Sallem, Souhir; Kammoun, M. B. A.

    2017-08-01

    This paper deals with voltage and frequency control of a stand-alone wind energy conversion system (WECS) based on a double fed induction generator (DFIG) under wind speed and load variations. In this context, two kinds of linear and nonlinear control strategies, classical PI and backstepping, have been applied to the system in real time. A series of experiments have been conducted to evaluate and to compare dynamic performances of the proposed control approaches. Experiments on a 1.5Kw doubly fed induction machine in real time are carried out using dSpace DS1104 card based on the MATLAB/Simulink environment. Experimental results show the validity of implemented controllers and demonstrate the effectiveness, the precision and the rapidity of the backstepping control strategy compared with the PI controller.

  12. An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

    Science.gov (United States)

    Gayen, P K; Chatterjee, D; Goswami, S K

    2016-05-01

    In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  13. About Eddy Currents in Induction Melting Processes

    Directory of Open Access Journals (Sweden)

    Gafiţa Nicolae-Bogdan

    2008-05-01

    Full Text Available In this paper we present a method forcomputing the eddy currents in induction meltingprocesses for non-ferrous alloys. We take intoconsideration the situation when only the crucible ismoving, inside the coils. This fact makes differentialcomputation methods to be hard to apply, because isnecessary to generate a new mesh and a new systemmatrix for every for every new position of the cruciblerelated to the coils. Integral methods cancel thisdrawback because the mesh is generated only for thedomains with eddy currents. For integral methods, themesh and the inductance matrix remain unchangedduring the movement of the crucible; only the free termsof the equation system will change.

  14. Understanding the effects of potassium ferricyanide on lead hydride formation in tetrahydroborate system and its application for determination of lead in milk using hydride generation inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Biyang, E-mail: dengby16@163.com; Xu, Xiangshu; Xiao, Yan; Zhu, Pingchuan; Wang, Yingzi

    2015-01-01

    Highlights: • Proposed a novel explanation for plumbane generation. • Expounded the role of K{sub 3}Fe(CN){sub 6} in plumbane generation. • Clarified the controversial aspects in the mechanism of K{sub 3}Fe(CN){sub 6} enhancement. • Used X-ray diffractometry to analyze the intermediates. • Developed a method to analyze lead in milk using K{sub 3}Fe(CN){sub 6} and K{sub 4}Fe(CN){sub 6} as new additives. - Absract: To understand the formation of plumbane in the Pb{sup II}-NaBH{sub 4}-K{sub 3}Fe(CN){sub 6} system, the intermediate products produced in the reaction of lead(II) and NaBH{sub 4} in the presence of K{sub 3}Fe(CN){sub 6} were studied. The produced plumbane and elemental lead were measured through continuous flow hydride generation (HG)-inductively coupled plasma optical emission spectrometry (ICP OES) and X-ray diffraction spectrometry techniques, respectively. Based on the experimental results, the explanations can be depicted in the following steps: (1) plumbane and black lead sediment (black Pb) are formed in the reaction of lead(II) and NaBH{sub 4}; (2) the black Pb is oxidized by K{sub 3}Fe(CN){sub 6} to form Pb{sub 2}[Fe(CN){sub 6}], which further reacts with NaBH{sub 4} to form more plumbane and black Pb; and (3) another round starts in which the produced black Pb from the step 2 is then oxidized continuously by K{sub 3}Fe(CN){sub 6} to form more Pb{sub 2}[Fe(CN){sub 6}] complex, which would produce more plumbane. In short, the black Pb and Pb{sub 2}[Fe(CN){sub 6}] complex are the key intermediate products for the formation of plumbane in the Pb{sup II}-NaBH{sub 4}-K{sub 3}Fe(CN){sub 6} system. Based on the enhancement effect of potassium ferricyanide and potassium ferrocyanide, a method was developed to analyze lead in milk with HG-ICP OES technique. The detection limit of the method was observed as 0.081 μg L{sup −1}. The linearity range of lead was found between 0.3 and 50,000 μg L{sup −1} with correlation coefficient of 0

  15. Comprehensive analysis of the dynamic behavior of grid-connected DFIG-based wind turbines under LVRT conditions

    DEFF Research Database (Denmark)

    Alsmadi, Yazan M.; Xu, Longya; Blaabjerg, Frede

    2015-01-01

    ) capability of wind turbines during grid faults is one of the core requirements to ensure stability in the power grid during transients. The doubly-fed induction generators (DFIGs) offer several advantages when utilized in wind turbines, but discussions about their LVRT capabilities are limited. This paper...... presents a comprehensive study of the LVRT of grid-connected DFIG-based wind turbines. It provides a detailed investigation of the transient characteristics and the dynamic behavior of DFIGs during symmetrical and asymmetrical grid voltage sags. A detailed theoretical study supported by computer......Power generation and grid stability have become key issues in the last decade. The high penetration of large capacity wind generation into the electric power grid has led to serious concerns about their influence on the dynamic behavior of power systems. The Low-Voltage Ride-Through (LVRT...

  16. Comparative Study of Voltage Recovery Behaviors of Grid-Connected Wind Turbines

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    on voltage recovery of variable speed wind turbines. The models of two different kinds of variable speed wind turbines, respectively with slip control and with doubly fed induction generator (DFIG), are developed in PSCAD/EMTDC. In both wind power generation systems, control strategies are proposed to re......The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the voltage at the wind turbine terminal should be re-established with minimized power losses. This paper concentrates......-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, which have been demonstrated by simulation results....

  17. Determination of fault operation dynamical constraints for the design of wind turbine DFIG drives

    CERN Document Server

    Aguglia, Davide; Wamkeue, René; Cros, Jérôme

    2010-01-01

    This paper presents an efficient design tool for the estimation of the transient electromagnetic peak torque and transient rotor over-voltages of wind turbines (WT) doubly-fed induction generators (DFIG) during severe fault conditions on the grid side. This versatile and robust tool is well adapted to the implementation in a DFIG drives CAD environment using iterative optimization procedures. In such an application, it is used to compute the dynamical constraints function during the integrated design process of the whole drive including the generator, the gearbox and the power converters. Results show that it is necessary to take into account the dynamical constraints under fault operation, during the early steps of the system design process. Another application of the tool is also illustrated in the paper: the design of the protection system (i.e. the crowbar resistance) for a given generator, a given gearbox and a given power converter.

  18. Review of induction LINACS

    International Nuclear Information System (INIS)

    Faltens, A.; Keefe, D.

    1981-10-01

    There has been a recent upsurge of activity in the field of induction linacs, with several new machines becoming operational and others in the design stages. The performance levels of electron machines have reached 10's of kiloamps of current and will soon reach 10's of MeV's of energy. Acceleration of ion current has been demonstrated, and the study of a 10 GeV heavy ion induction linac for ICF continues. The operating principles of induction linacs are reviewed with the emphasis on design choices which are important for increasing the maximum beam currents

  19. Review of induction linacs

    International Nuclear Information System (INIS)

    Faltens, A.; Keefe, D.

    1982-01-01

    There has been a recent upsurge of activity in the field of induction linacs, with several new machines becoming operational and others in the design stages. The performance levels of electron machines have reached 10's of kiloamps of current and will soon reach 10's of MeV's of energy. Acceleration of several kiloamps of ion current has been demonstrated, and the study of a 10 GeV heavy ion induction linac for ICF continues. The operating principles of induction linacs are reviewed with the emphasis on design choices which are important for increasing the maximum beam currents

  20. Properties of inductive reasoning.

    Science.gov (United States)

    Heit, E

    2000-12-01

    This paper reviews the main psychological phenomena of inductive reasoning, covering 25 years of experimental and model-based research, in particular addressing four questions. First, what makes a case or event generalizable to other cases? Second, what makes a set of cases generalizable? Third, what makes a property or predicate projectable? Fourth, how do psychological models of induction address these results? The key results in inductive reasoning are outlined, and several recent models, including a new Bayesian account, are evaluated with respect to these results. In addition, future directions for experimental and model-based work are proposed.

  1. Induction linac driven relativistic klystron and cyclotron autoresonance maser experiments

    International Nuclear Information System (INIS)

    Goodman, D.L.; Birx, D.L.; Danly, B.G.

    1991-01-01

    In this paper design and experimental results are presented from two high power microwave generation experiments utilizing a high repetition rate induction linac generated electron beam. A relativistic klystron has generated more than 100 MW microwave pulses in X-band for 50 ns without pulse shortening or breakdown. design studies for the first cyclotron autoresonance maser (CARM) amplifier using an induction linac electron beam are also presented

  2. Simulation for Grid Connected Wind Turbines with Fluctuating

    Science.gov (United States)

    Ye, Ying; Fu, Yang; Wei, Shurong

    This paper establishes the whole dynamic model of wind turbine generator system which contains the wind speed model and DFIG wind turbines model .A simulation sample based on the mathematical models is built by using MATLAB in this paper. Research are did on the performance characteristics of doubly-fed wind generators (DFIG) which connected to power grid with three-phase ground fault and the disturbance by gust and mixed wind. The capacity of the wind farm is 9MW which consists of doubly-fed wind generators (DFIG). Simulation results demonstrate that the three-phase ground fault occurs on grid side runs less affected on the stability of doubly-fed wind generators. However, as a power source, fluctuations of the wind speed will run a large impact on stability of double-fed wind generators. The results also show that if the two disturbances occur in the meantime, the situation will be very serious.

  3. Induction melter apparatus

    Science.gov (United States)

    Roach, Jay A [Idaho Falls, ID; Richardson, John G [Idaho Falls, ID; Raivo, Brian D [Idaho Falls, ID; Soelberg, Nicholas R [Idaho Falls, ID

    2008-06-17

    Apparatus and methods of operation are provided for a cold-crucible-induction melter for vitrifying waste wherein a single induction power supply may be used to effect a selected thermal distribution by independently energizing at least two inductors. Also, a bottom drain assembly may be heated by an inductor and may include an electrically resistive heater. The bottom drain assembly may be cooled to solidify molten material passing therethrough to prevent discharge of molten material therefrom. Configurations are provided wherein the induction flux skin depth substantially corresponds with the central longitudinal axis of the crucible. Further, the drain tube may be positioned within the induction flux skin depth in relation to material within the crucible or may be substantially aligned with a direction of flow of molten material within the crucible. An improved head design including four shells forming thermal radiation shields and at least two gas-cooled plenums is also disclosed.

  4. Linear induction accelerator

    Science.gov (United States)

    Buttram, M.T.; Ginn, J.W.

    1988-06-21

    A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.

  5. Linear induction accelerators

    International Nuclear Information System (INIS)

    Briggs, R.J.

    1986-06-01

    The development of linear induction accelerators has been motivated by applications requiring high-pulsed currents of charged particles at voltages exceeding the capability of single-stage, diode-type accelerators and at currents too high for rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multi-stage induction machine, but the 50-MeV, 10-kA Advanced Test Accelerator (ATA) at LLNL is the highest voltage machine in existence at this time. The advent of magnetic pulse power systems makes sustained operation at high-repetition rates practical, and this capability for high-average power is very likely to open up many new applications of induction machines in the future. This paper surveys the US induction linac technology with primary emphasis on electron machines. A simplified description of how induction machines couple energy to the electron beam is given, to illustrate many of the general issues that bound the design space of induction linacs

  6. Coordinated control strategy for hybrid wind farms with DFIG-based and PMSG-based wind farms during network unbalance

    DEFF Research Database (Denmark)

    Yao, Jun; Liu, Ruikuo; Zhou, Te

    2017-01-01

    This paper investigates the coordinated control strategy for a hybrid wind farm with doubly fed induction generator (DFIG)-based and direct-driven permanent-magnet synchronous generator (PMSG)-based wind farms during network unbalance. The negative-sequence current output capabilities of DFIG...... to the controllable operating regions, a targets selection scheme for each control unit is proposed to improve the stability of the hybrid wind farms containing both DFIG-based and PMSG-based wind farms during network unbalance, especially to avoid DFIG-based wind farm tripping from connected power grid under severe...... grid voltage unbalance conditions. Finally, the proposed coordinated control strategy is validated by the simulation results of a 30-MW-DFIG-based wind farm and a 30-MW-PMSG-based wind farm under different operation conditions and experimental results on a laboratory-scale experimental rig under severe...

  7. Coordination between Fault-Ride-Through Capability and Overcurrent Protection of DFIG Generatorsfor Wind Farms

    DEFF Research Database (Denmark)

    Bak-Jensen, Birgitte; Kawady, Tamer A.; Abdel-Rahman, Mansour H.

    2009-01-01

    Due to the increasing penetration of wind farms in power systems, stability issues arise strongly for power system operation. Doubly-Fed Induction Generators (DFIG) are charac-terized with some unique features during normal/abnormal op-erating conditions as compared with singly-fed ones. Fault ri...... on protective relaying coordination in wind farms.......-Through (FRT) mainly aims to delay a disconnecting of the DFIG units during grid faults for a possible time to restore the system stability if the fault is cleared within a permissible time. This strategy may, however, affect the performance of related protective elements during fault periods. In this paper......, the Coor-dination between Fault Ride-Through Capability and Overcur-rent Protection of DFIG Wind Generators in MV Networks is in-vestigated. Simulation test cases using MATLAB-Simulink are implemented on a 345-MW wind farm in AL-Zaafarana, Egypt. The simulation results show the influence of FRT capability...

  8. Grid connection of active stall wind farms using a VSC based DC transmission system

    DEFF Research Database (Denmark)

    Iov, F.; Sørensen, Poul Ejnar; Hansen, A.D.

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern...... wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...

  9. Modeling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sorensen, Poul; Hansen, Anca-Daniela

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modem wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  10. Modelling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

    2006-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  11. Variable frequency operation of active stall wind farms using a dc connection to grid

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede; Sorensen, Poul

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmISSIon system. Requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern...... wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...

  12. Feedback Linearization Controller for a Wind Energy Power System

    Directory of Open Access Journals (Sweden)

    Muthana Alrifai

    2016-09-01

    Full Text Available This paper deals with the control of a doubly-fed induction generator (DFIG-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with back-to-back three-phase power converter bridges between its rotor and the grid; it is modeled using the direct-quadrature rotating reference frame with aligned stator flux. An input-state feedback linearization controller is proposed for the wind energy power system. The controller guarantees that the states of the system track the desired states. Simulation results are presented to validate the proposed control scheme. Moreover, further simulation results are shown to investigate the robustness of the proposed control scheme to changes in some of the parameters of the system.

  13. Improved fault ride through capability of DFIG based wind turbines using synchronous reference frame control based dynamic voltage restorer.

    Science.gov (United States)

    Rini Ann Jerin, A; Kaliannan, Palanisamy; Subramaniam, Umashankar

    2017-09-01

    Fault ride through (FRT) capability in wind turbines to maintain the grid stability during faults has become mandatory with the increasing grid penetration of wind energy. Doubly fed induction generator based wind turbine (DFIG-WT) is the most popularly utilized type of generator but highly susceptible to the voltage disturbances in grid. Dynamic voltage restorer (DVR) based external FRT capability improvement is considered. Since DVR is capable of providing fast voltage sag mitigation during faults and can maintain the nominal operating conditions for DFIG-WT. The effectiveness of the DVR using Synchronous reference frame (SRF) control is investigated for FRT capability in DFIG-WT during both balanced and unbalanced fault conditions. The operation of DVR is confirmed using time-domain simulation in MATLAB/Simulink using 1.5MW DFIG-WT. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Transient Analysis of Grid-Connected Wind Turbines with DFIG After an External Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the grid-connected wind turbine should restore its normal operation with minimized power losses. This paper concentrates...... on transient analysis of variable speed wind turbines with doubly fed induction generator (DFIG) after an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described in detail....... After the clearance of an external short-circuit fault the control schemes manage to restore the wind turbine?s normal operation, and their performances are demonstrated by simulation results both during the fault and after the clearance of the fault....

  15. H∞ Robust Current Control for DFIG Based Wind Turbine subject to Grid Voltage Distortions

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Gong, Wenming

    2016-01-01

    This paper proposes an H∞ robust current controller for doubly fed induction generator (DFIG) based wind turbines (WTs) subject to grid voltage distortions. The controller is to mitigate the impact of the grid voltage distortions on rotor currents with DFIG parameter perturbation. The grid voltage...... distortions considered include asymmetric voltage dips and grid background harmonics. An uncertain DFIG model is developed with uncertain factors originating from distorted stator voltage, and changed generator parameters due to the flux saturation effect, the skin effect, etc. Weighting functions...... are designed to efficiently track the unbalanced current components and the 5th and 7th background harmonics. The robust stability (RS) and robust performance (RP) of the proposed controller are verified by the structured singular value µ. The performance of the H∞ robust current controller was demonstrated...

  16. Transient stability probability evaluation of power system incorporating with wind farm and SMES

    DEFF Research Database (Denmark)

    Fang, Jiakun; Miao, Lu; Wen, Jinyu

    2013-01-01

    Large scale renewable power generation brings great challenges to the power system operation and stabilization. Energy storage is one of the most important technologies to face the challenges. This paper proposes a method for transient stability probability evaluation of power system with wind farm...... and SMES. Firstly, a modified 11-bus test system with both wind farm and SMES has been implemented. The wind farm is represented as a doubly fed induction generator (DFIG). Then a stochastic-based approach to evaluate the probabilistic transient stability index of the power system is presented. Uncertain...... the probability indices. With the proposed method based on Monte-Carlo simulation and bisection method, system stability is "measured". Quantitative relationship of penetration level, SMES coil size and system stability is established. Considering the stability versus coil size to be the production curve...

  17. Flicker Mitigation by Individual Pitch Control of Variable Speed Wind Turbines With DFIG

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Hu, Weihao

    2014-01-01

    generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) strategy is proposed to reduce the flicker emission at different wind speed conditions. The IPC scheme is proposed and the individual pitch controller is designed according to the generator active power...... and the azimuth angle of the wind turbine. The simulations are performed on the NREL (National Renewable Energy Laboratory) 1.5-MW upwind reference wind turbine model. Simulation results show that damping the generator active power by IPC is an effective means for flicker mitigation of variable speed wind......Due to the wind speed variation, wind shear and tower shadow effects, grid connected wind turbines are the sources of power fluctuations which may produce flicker during continuous operation. This paper presents a model of an MW-level variable-speed wind turbine with a doubly fed induction...

  18. Modelling, Analysis and Control of DC-connected Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

    2006-01-01

    wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...... of the active stall wind farms to the grid can provide these features and also maximize the produced power especially at low wind speeds by using variable voltage/frequency for the wind farm. The focus in this paper is in studying the variable speed operation for the active stall wind farms using a voltage...

  19. Proportional resonant individual pitch control for mitigation of wind turbines loads

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Cheng, Ming

    2013-01-01

    attenuation. The individual pitch control (IPC) is a promising way to reduce the wind turbine loads. This study presents a proportional resonant (PR) IPC, which does not need the measurement of blade azimuth angle and multiple complex Coleman transformations between rotational coordinate frame and stationary...... coordinate frame. The new strategy can attenuate the 1p and higher harmonics on the wind turbine blades as well as 3p on the hub without any filters. The wind turbine code fatigue, aerodynamics, structures and turbulence is applied to a doubly fed induction generator-based wind power generation system....... The simulations are performed on the National Renewable Energy Laboratory 1.5 MW upwind reference wind turbine model. The simulation results are presented and discussed to demonstrate the capability and effectiveness of the proposed PR IPC method....

  20. Automatic design of decision-tree induction algorithms

    CERN Document Server

    Barros, Rodrigo C; Freitas, Alex A

    2015-01-01

    Presents a detailed study of the major design components that constitute a top-down decision-tree induction algorithm, including aspects such as split criteria, stopping criteria, pruning, and the approaches for dealing with missing values. Whereas the strategy still employed nowadays is to use a 'generic' decision-tree induction algorithm regardless of the data, the authors argue on the benefits that a bias-fitting strategy could bring to decision-tree induction, in which the ultimate goal is the automatic generation of a decision-tree induction algorithm tailored to the application domain o

  1. Coil geometry models for power loss analysis and hybrid inductive ...

    Indian Academy of Sciences (India)

    CHANDRASEKHARAN NATARAJ

    2018-04-26

    Apr 26, 2018 ... most of the WPT systems, but often suffers from power loss in the near field area of inductively coupled ... applications in the area of Distribution Generation (DG) ... embedded sensors, and buried devices, work at low voltage.

  2. Floating Inductance and FDNR Using Positive Polarity Current Conveyors

    Directory of Open Access Journals (Sweden)

    K. Pal

    2004-01-01

    Full Text Available A generalized circuit based on five positive polarity second-generation current conveyors is introduced. The circuit simulates a floating inductance, capacitor floatation circuit and floating fdnr. All these circuits use grounded capacitors.

  3. Inductive dielectric analyzer

    International Nuclear Information System (INIS)

    Agranovich, Daniel; Popov, Ivan; Ben Ishai, Paul; Feldman, Yuri; Polygalov, Eugene

    2017-01-01

    One of the approaches to bypass the problem of electrode polarization in dielectric measurements is the free electrode method. The advantage of this technique is that, the probing electric field in the material is not supplied by contact electrodes, but rather by electromagnetic induction. We have designed an inductive dielectric analyzer based on a sensor comprising two concentric toroidal coils. In this work, we present an analytic derivation of the relationship between the impedance measured by the sensor and the complex dielectric permittivity of the sample. The obtained relationship was successfully employed to measure the dielectric permittivity and conductivity of various alcohols and aqueous salt solutions. (paper)

  4. Lessons for Inductive Germline Determination

    Science.gov (United States)

    Seervai, Riyad N.H.; Wessel, Gary M.

    2015-01-01

    SUMMARY Formation of the germline in an embryo marks a fresh round of reproductive potential, yet the developmental stage and location within the embryo where the primordial germ cells (PGCs) form differs wildly among species. In most animals, the germline is formed either by an inherited mechanism, in which maternal provisions within the oocyte drive localized germ-cell fate once acquired in the embryo, or an inductive mechanism that involves signaling between cells that directs germ-cell fate. The inherited mechanism has been widely studied in model organisms such as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis, and Danio rerio. Given the rapid generation time and the effective adaptation for laboratory research of these organisms, it is not coincidental that research on these organisms has led the field in elucidating mechanisms for germline specification. The inductive mechanism, however, is less well understood and is studied primarily in the mouse (Mus musculus). In this review, we compare and contrast these two fundamental mechanisms for germline determination, beginning with the key molecular determinants that play a role in the formation of germ cells across all animal taxa. We next explore the current understanding of the inductive mechanism of germ-cell determination in mice, and evaluate the hypotheses for selective pressures on these contrasting mechanisms. We then discuss the hypothesis that the transition between these determination mechanisms, which has happened many times in phylogeny, is more of a continuum than a binary change. Finally, we propose an analogy between germline determination and sex determination in vertebrates—two of the milestones of reproduction and development—in which animals use contrasting strategies to activate similar pathways. PMID:23450642

  5. Dragon-I Linear Induction Electron Accelerator

    International Nuclear Information System (INIS)

    Ding Bonan; Deng Jianjun; Wang Huacen; Cheng Nian'an; Dai Guangsen; Zhang Linwen; Liu Chengjun; Zhang Wenwei; Li Jin; Zhang Kaizhi

    2005-01-01

    Dragon-I is a linear induction electron accelerator. This facility consists of a 3.6 MeV injector, 38 meter beam transport line and 16 MeV induction accelerator powered by high voltage generators, including 8 Marx generators and 48 Blumlein lines. This paper describes the physics design, development and experimental results of Dragon-I. The key technology is analyzed in the accelerator development, and the design requirements and operation of the major subsystems are presented. The experimental results show Dragon-I generates an 18-20 MeV, 2.5 kA, 70 ns electron beam. The X-ray spot size is about 1.2 mm and dose level about 0.103 C/kg at 1 meter. (authors)

  6. Linear active disturbance rejection-based load frequency control concerning high penetration of wind energy

    International Nuclear Information System (INIS)

    Tang, Yanmei; Bai, Yan; Huang, Congzhi; Du, Bin

    2015-01-01

    Highlights: • A disturbance rejection solution to the load frequency control issue is proposed. • Several power systems with wind energy conversation system have been tested. • A tuning algorithm of the controller parameters was proposed. • The performance of the proposed approach is better than traditional controllers. - Abstract: A new grid load frequency control approach is proposed for the doubly fed induction generator based wind power plants. The load frequency control issue in a power system is undergoing fundamental changes due to the rapidly growing amount of wind energy conversation system, and concentrating on maintaining generation-load balance and disturbance rejection. The prominent feature of the linear active disturbance rejection control approach is that the total disturbance can be estimated and then eliminated in real time. And thus, it is a feasible solution to deal with the load frequency control issue. In this paper, the application of the linear active disturbance rejection control approach in the load frequency control issue for a complex power system with wind energy conversation system based on doubly fed induction generator is investigated. The load frequency control issue is formulated as a decentralized multi-objective optimization control problem, the solution to which is solved by the hybrid particle swarm optimization technique. To show the effectiveness of the proposed control scheme, the robust performance testing based on Monte-Carlo approach is carried out. The performance superiority of the system with the proposed linear active disturbance rejection control approach over that with the traditional proportional integral and fuzzy-proportional integral-based controllers is validated by the simulation results

  7. Analysis of High Frequency Resonance in DFIG-based Offshore Wind Farm via Long Transmission Cable

    DEFF Research Database (Denmark)

    Song, Yipeng; Ebrahimzadeh, Esmaeil; Blaabjerg, Frede

    2018-01-01

    During the past two decades, the Doubly Fed Induction Generator (DFIG) based wind farm has been under rapid growth, and the increasing wind power penetration has been seen. Practically, these wind farms are connected to the three-phase AC grid through long transmission cable which can be modelled...... as several II units. The impedance of this cable cannot be neglected and requires careful investigation due to its long distance. As a result, the impedance interaction between the DFIG based wind farm and the long cable is inevitable, and may produce High Frequency Resonance (HFR) in the wind farm....... This paper discusses the HFR of the large scale DFIG based wind farm connected to the long cable. Several influencing factors, including 1) the length of the cable, 2) the output active power and 3) the rotor speed, are investigated. Simulation validations using MATLAB / Simulink have been conducted...

  8. Micro grid control strategy of DFIG unit based on improved DC grid connected topology

    Science.gov (United States)

    Zongze, Xia; Fei, Xia; Zhixiong, Yang

    2017-05-01

    Aiming to the application of the DFIG connected to DC-Microgrids, an improved topology for the DFIG connected to DC-Microgrids is taken into account in this thesis. The stator side loses the support of voltage and frequency of AC point of common coupling bus. A novel control method suitable to the stator side converter (SSC) and the rotor side converter (RSC) of the topology is proposed. The independent control of stator voltage and frequency, the decoupled control of power and variable speed constant frequency of DFIG are achieved in the doubly-fed induction generator connected to DC-Microgrids. which can enhance the capacity of active power transmission of DFIG during the voltage variation.

  9. Operation and control of large wind turbines and wind farms. Final report

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Hansen, Anca Daniela; Thomsen, Kenneth

    2005-01-01

    good power quality and limit mechanical loads and life time consumption. The projectdeveloped models for 3 different concepts for wind farms. Two of the concepts use active stall controlled wind turbines, one with AC connection and one with modern HVDC/VSC connection of the wind farm. The third concept...... is based on pitch controlled windturbines using doubly fed induction generators. The models were applied to simulate the behaviour of the wind farm control when they were connected to a strong grid, and some initial simulations were performed to study the behaviour of the wind farms whenit was isolated...... concepts. The potentials of optimising the lifetime/energy production ratio by means of using revised operational strategies for the individual wind turbines are investigated. Different strategies have beensimulated, where the power production is decreased to an optimum when taking loads and actual price...

  10. Enhancing LVRT of DFIG by Using a Superconducting Current Limiter on Rotor Circuit

    Directory of Open Access Journals (Sweden)

    Flávio Oliveira

    2015-12-01

    Full Text Available This paper have studied the dynamic of a 2.0 MW Doubly Fed Induction Generator (DFIG during a severe voltage sag. Using the dynamic model of a DFIG, it was possible to determine the current, Electromagnetic Force and flux behavior during three-phase symmetrical voltage dip. Among the technologies of wind turbines the DFIG is widely employed; however, this machine is extremely susceptible to disturbances from the grid. In order to improve DFIG Low Voltage Ride-Through (LVRT, it is proposed a novel solution, using Superconducting Current Limiter (SCL in two arrangements: one, the SCL is placed between the machine rotor and the rotor side converter (RSC, and another placed in the RSC DC-link. The proposal is validated through simulation using PSCAD™/EMTDC™ and according to requirements of specific regulations. The analysis ensure that both SCL arrangements behave likewise, and are effective in decrement the rotor currents during the disturbance.

  11. Security and Stability Analysis of Wind Farms Integration into Distribution Network

    Science.gov (United States)

    Guan-yang, Li; Hongzhao, Wang; Guanglei, Li; Yamei, Cheng; Hong-zheng, Liu; Yi, Sun

    2017-05-01

    With the increasing share of the wind power in the power system, wind power fluctuations will cause obvious negative impacts on weak local grid. This paper firstly establish electromechanical transient simulation model for doubly fed induction wind turbine, then use Matlab/Simulink to achieve power flow calculation and transient simulation of power system including wind farms, the local synchronous generator, load, etc, finally analyze wind power on the impact of the local power grid under typical circumstances. The actual calculated results indicate that wind mutation causes little effect on the power grid, but when the three-phase short circuit fault happens, active power of wind power decreases sharply and the voltage of location of wind power into the grid also drop sharply, finally wind farm split from power system. This situation is not conducive to security and stability of the local power grid. It is necessary to develop security and stability measures in the future.

  12. Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

    Science.gov (United States)

    Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

    2017-01-01

    The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as strategic thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of alternating current (AC) and direct current (DC) for power generation, transmission, and distribution. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power system, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of doubly-fed induction machines (DFIMs), which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the activity along with the system architecture, development status, and preliminary results.

  13. Sustainable Energy Solutions Task 1.0: Networked Monitoring and Control of Small Interconnected Wind Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    edu, Janet. twomey@wichita. [Wichita State Univ., KS (United States)

    2010-04-30

    This report presents accomplishments, results, and future work for one task of five in the Wichita State University Sustainable Energy Solutions Project: To develop a scale model laboratory distribution system for research into questions that arise from networked control and monitoring of low-wind energy systems connected to the AC distribution system. The lab models developed under this task are located in the Electric Power Quality Lab in the Engineering Research Building on the Wichita State University campus. The lab system consists of four parts: 1. A doubly-fed induction generator 2. A wind turbine emulator 3. A solar photovoltaic emulator, with battery energy storage 4. Distribution transformers, lines, and other components, and wireless and wired communications and control These lab elements will be interconnected and will function together to form a complete testbed for distributed resource monitoring and control strategies and smart grid applications testing. Development of the lab system will continue beyond this project.

  14. Application of SMES in wind farm to improve voltage stability

    International Nuclear Information System (INIS)

    Shi, J.; Tang, Y.J.; Ren, L.; Li, J.D.; Chen, S.J.

    2008-01-01

    For the wind farms introducing doubly fed induction generators (DFIGs), voltage stability is an essential issue which influences their widely integration into the power grid. This paper proposes the application of superconducting magnetic energy storage (SMES) in the power system integrated with wind farms. SMES can control the active and reactive power flow, realizing the operation in four quadrants independently. The introducing of SMES can smooth the output power flow of the wind farms, and supply dynamic voltage support. Using MATLAB/SIMULINK, the models of the DFIG, the power grid connected and the SMES are created. Simulation results show that the voltage stability of the power system integrated with wind farms can be improved considerably

  15. Design of current controller of grid-connected voltage source converter based internal model control in wind power

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xianping; Guo Jindong; Xu Honghua [Inst. of Electrical Engineering, Chinese Academy of Sciences, BJ (China)

    2008-07-01

    Grid-connected voltage source converter (VSC) is important for variable speed turbines with doubly fed induction generator (DFIG), and bad performance of current loop of VSC may cause VSC inject much low and high order harmonics into grid. Therefore, design of current controller of VSC is very important. PI regulator is often used to regulate current error in dq rotating coordinate to obtain zero steady error. However, it is complex to design PI parameters, and researchers need many trial-and-error steps. Therefore, a novel and simple design method of PI regulator for grid-connected VSC, which is based internal model control (IMC), has been presented in this paper. The parameters of PI regulator can be expressed directly with certain L-type line filter parameters and the desired closed-loop bandwidth. At last, The simulation has been done and result shows that the method in this paper is easy and useful to regulate PI parameters. (orig.)

  16. Adaptive Voltage Control Strategy for Variable-Speed Wind Turbine Connected to a Weak Network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Chen, Zhe

    2016-01-01

    and smoothness at the point of connection (POC) in order to maximise the wind power penetration into such networks. Intensive simulation case studies under different network topology and wind speed ranges reveal the effectiveness of the AVC scheme to effectively suppress the POC voltage variations particularly......Significant voltage fluctuations and power quality issues pose considerable constraints on the efficient integration of remotely located wind turbines into weak networks. Besides, 3p oscillations arising from the wind shear and tower shadow effects induce further voltage perturbations during...... continuous operation. This study investigates and analyses the repercussions raised by integrating a doubly-fed induction generator wind turbine into an ac network of different parameters and very weak conditions. An adaptive voltage control (AVC) strategy is proposed to retain voltage constancy...

  17. Application of Multipoint DC Voltage Control in VSC-MTDC System

    Directory of Open Access Journals (Sweden)

    Yang Xi

    2013-01-01

    Full Text Available The voltage-source-converter- (VSC- based multiterminal VSC-HVDC power transmission system (VSC-MTDC is an ideal approach to connect wind farm with power grid. Analyzing the characteristics of doubly fed induction generators as well as the basic principle and the control strategy of VSC-MTDC, a multiterminal DC voltage control strategy suitable for wind farm connected with VSC-MTDC is proposed. By use of PSCAD/EMTDC, the proposed control strategy is simulated, and simulation results show that using the proposed control strategy the conversion between constant power control mode and constant DC voltage control mode can be automatically implemented; thus the DC voltage stability control and reliable power output of wind farm can be ensured after the fault-caused outage of converter station controlled by constant DC voltage and under other faults. The simulation result shows that the model can fulfill multiterminal power transmission and fast response control.

  18. A control strategy for grid-side converter of DFIG under unbalanced condition based on Dig SILENT/Power Factory

    Science.gov (United States)

    Han, Pingping; Zhang, Haitian; Chen, Lingqi; Zhang, Xiaoan

    2018-01-01

    The models of doubly fed induction generator (DFIG) and its grid-side converter (GSC) are established under unbalanced grid condition based on DIgSILENT/PowerFactory. According to the mathematical model, the vector equations of positive and negative sequence voltage and current are deduced in the positive sequence synchronous rotating reference frame d-q-0 when the characteristics of the simulation software are considered adequately. Moreover, the reference value of current component of GSC in the positive sequence frame d-q-0 under unbalanced condition can be obtained to improve the traditional control of GSC when the national issue of unbalanced current limits is combined. The simulated results indicate that the control strategy can restrain negative sequence current and the two times frequency power wave of GSC’s ac side effectively. The voltage of DC bus can be maintained a constant to ensure the uninterrupted operation of DFIG under unbalanced grid condition eventually.

  19. Sliding Mode Control of DFIG Wind Turbines with a Fast Exponential Reaching Law

    Directory of Open Access Journals (Sweden)

    Linyun Xiong

    2017-11-01

    Full Text Available This paper proposes a novel sliding mode control (SMC technique for doubly fed induction generators (DFIGs based on the fast exponential reaching law (FERL. The proposed FERL-based SMC is capable of reducing to a large extent the chattering phenomena existing in the sliding stage. Meanwhile, the reaching stage is accelerated with the introduction of an adaptive gain. The proposed method is employed in a DFIG-based wind energy conversion system (WECS for direct power control (DPC. The FERL-based DPC approach is tested with simulations conducted in Matlab/Simulink under the scenarios of unbalanced grid voltage, grid fault conditions and highly unstable wind speed accompanied by an experimental study. The simulations and experimental results reveal the better performance of the proposed control method in active/reactive power tracking and dc-link voltage maintenance.

  20. A Review on Direct Power Control for Applications to Grid Connected PWM Converters

    Directory of Open Access Journals (Sweden)

    T. A. Trivedi

    2015-08-01

    Full Text Available The Direct Power Control strategy has become popular as an alternative to the conventional vector oriented control strategy for grid connected PWM converters. In this paper, Direct Power Control as applied to various applications of grid connected converters is reviewed. The Direct Power Control for PWM rectifiers, Grid Connected DC/AC inverters applications such as renewable energy sources interface, Active Power Filters, Doubly Fed Induction Generators and AC-DC-AC converters are discussed. Control strategies such as Look-Up table based control, predictive control, Virtual Flux DPC, Model based DPC and DPC-Space Vector Modulation are critically reviewed. The effects of various key parameters such as selection of switching vector, sampling time, hysteresis band and grid interfacing on performance of direct power controlled converters are presented.

  1. Dual-loop control strategy for DFIG-based Wind turbines under grid voltage disturbances

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Tang, Yi

    2016-01-01

    , but also decay the stator transient flux, and avoid the accumulation of the stator transient flux. Moreover, the proposed strategy can obtain nearly constant stator active power and electromagnetic torque, which may prolong the lifetime of the drive train. A case study on a typical 2-MW DFIG-based wind......For a multimegawatts doubly-fed induction generator (DFIG), the grid voltage disturbances may affect the stator flux and induce the transient stator flux, due to the direct connection of the stator and the grid. The accumulation of the transient stator flux caused by the variations of the stator...... turbine demonstrating the effectiveness of the proposed control methods is verified with simulations in MATLAB/Simulink. The proposed control methods are also experimentally validated using a scaled-down 7.5-kW DFIG. The simulation and experimental results clearly validate the effectiveness...

  2. Wake Effects on Lifetime Distribution in DFIG-based Wind Farms

    DEFF Research Database (Denmark)

    Tian, Jie; Zhou, Dao; Su, Chi

    2017-01-01

    With the increasing size of the wind farms, the impact of the wake effect on the energy yields and lifetime consumption of wind turbine can no longer be neglected. In this paper, the affecting factors like the wind speed and wind direction are investigated in terms of the single wake and multiple...... wakes. As the power converter is the most fragile component among the turbine system, its lifetime estimation can be calculated seen from the thermal stress of the power semiconductor. On the basis of the relationship of the power converter in a 5 MW Doubly-Fed Induction Generator (DFIG) wind turbine...... system and the wind speed, the lifetime consumption of the individual turbine in a 10-turbine and an 80-turbine wind farms can be calculated by considering the real distributions of the wind speed and direction. It can be seen that there is significant lifetime difference among individual turbines...

  3. Co-ordinated voltage control of DFIG wind turbines in uninterrupted operation during grid faults

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Michalke, G.; Sørensen, Poul Ejnar

    2007-01-01

    Emphasis in this article is on the design of a co-ordinated voltage control strategy for doubly fed induction generator (DFIG) wind turbines that enhances their capability to provide grid support during grid faults. In contrast to its very good performance in normal operation, the DFIG wind turbine...... concept is quite sensitive to grid faults and requires special power converter protection. The fault ride-through and grid support capabilities of the DFIG address therefore primarily the design of DFIG wind turbine control with special focus on power converter protection and voltage control issues....... A voltage control strategy is designed and implemented in this article, based on the idea that both converters of the DFIG (i.e. rotor-side converter and grid-side converter) participate in the grid voltage control in a co-ordinated manner. By default the grid voltage is controlled by the rotor...

  4. Damping control strategies of inter-area low-frequency oscillation for DFIG-based wind farms integrated into a power system

    DEFF Research Database (Denmark)

    Li, Hui; Liu, Shengquan; Ji, Haiting

    2014-01-01

    on the power system stabilizer (PSS) control method. Transient simulation on different damping gain coefficients are conducted for justification. Following the OTEF mechanism analysis, an additional fuzzy damping control strategy with the active/reactive power loop is proposed by identifying the oscillation......This study investigates the inter-area low-frequency damping control strategies of a doubly fed induction generator (DFIG)-based wind farm through oscillation transient energy function (OTEF) analysis. Based on the OTEF descent expressions, the feasibility of damping the inter-area low...... oscillation of the wind turbine shaft. The proposed additional fuzzy control strategy with the active/reactive power loop has better damping performance than the presented PSS control, especially for damping the inter-area low-frequency oscillation....

  5. Impedance Based Analysis of DFIG Stator Current Unbalance and Distortion Suppression Strategies

    DEFF Research Database (Denmark)

    Song, Yipeng; Zhou, Dao; Blaabjerg, Frede

    2016-01-01

    The control strategies of Doubly Fed Induction Generator (DFIG) system output current unbalance and distortion suppression have been well investigated in detail, with the implementation of two kinds of resonant regulators, i.e., conventional Resonance (R) regulator or Vector Proportional Integral...... reshaping though the introduction of R and VPI regulator. It is pointed out that, when implemented in the DFIG system output current unbalance and distortion suppression, the VPI regulator (equivalent to the combination of virtual positive inductor and virtual positive resistor) has two advantages over R...... regulator (equivalent to the combination of virtual positive resistor and virtual negative inductor), i.e., better high order harmonic distortion suppression. The theoretical analysis and MATLAB simulation results have validated the correctness of this conclusion....

  6. Reliability Evaluation of Power Capacitors in a Wind Turbine System

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede

    2018-01-01

    With the increasing penetration of wind power, reliable and cost-effective wind energy production is of more and more importance. The doubly-fed induction generator based partial-scale wind power converter is still dominating in the existing wind farms. In this paper, the reliability assessment...... block diagram is used to bridge the gap between the Weibull distribution based component-level individual capacitor and the capacitor bank. A case study of a 2 MW wind power converter shows that the lifetime is significantly reduced from the individual capacitor to the capacitor bank. Besides, the dc...... of power capacitors is studied considering the annual mission profile. According to an electro-thermal stress evaluation, the time-to-failure distribution of both the dc-link capacitor and ac-side filter capacitor is detailed investigated. Aiming for the systemlevel reliability analysis, a reliability...

  7. Review of reactive power dispatch strategies for loss minimization in a DFIG-based wind farm

    DEFF Research Database (Denmark)

    Zhang, Baohua; Hu, Weihao; Hou, Peng

    2017-01-01

    power control strategies are investigated. All of the combined strategies are formulated based on the comprehensive loss models of WFs, including the loss models of DFIGs, converters, filters, transformers, and cables of the collection system. Optimization problems are solved by a Modified Particle......This paper reviews and compares the performance of reactive power dispatch strategies for the loss minimization of Doubly Fed Induction Generator (DFIG)-based Wind Farms (WFs). Twelve possible combinations of three WF level reactive power dispatch strategies and fourWind Turbine (WT) level reactive...... Swarm Optimization (MPSO) algorithm. The effectiveness of these strategies is evaluated by simulations on a carefully designed WF under a series of cases with different wind speeds and reactive power requirements of the WF. The wind speed at each WT inside the WF is calculated using the Jensen wake...

  8. Offset-Free Direct Power Control of DFIG Under Continuous-Time Model Predictive Control

    DEFF Research Database (Denmark)

    Errouissi, Rachid; Al-Durra, Ahmed; Muyeen, S.M.

    2017-01-01

    This paper presents a robust continuous-time model predictive direct power control for doubly fed induction generator (DFIG). The proposed approach uses Taylor series expansion to predict the stator current in the synchronous reference frame over a finite time horizon. The predicted stator current...... is directly used to compute the required rotor voltage in order to minimize the difference between the actual stator currents and their references over the predictive time. However, as the proposed strategy is sensitive to parameter variations and external disturbances, a disturbance observer is embedded...... into the control loop to remove the steady-state error of the stator current. It turns out that the steady-state and the transient performances can be identified by simple design parameters. In this paper, the reference of the stator current is directly calculated from the desired stator active and reactive powers...

  9. Wind Power Fluctuation Smoothing Controller Based on Risk Assessment of Grid Frequency Deviation in an Isolated System

    DEFF Research Database (Denmark)

    Lin, Jin; Sun, Yuanzhang; Song, Yonghua

    2013-01-01

    a smoothing controller to suppress the power fluctuation from doubly-fed induction generator (DFIG)-based wind farm. This controller consists of threemain functionality components: risk assessmentmodel, wind turbine rotor speed optimizer, and rotor speed upper limiter. In order to avoid unnecessary energy...... curve with reduced output so that a trade-off between fluctuation smoothing and energy loss is achieved. Subsequently, the controller limits the maximum rotor speed to shift down the power curve of wind power plant based on the optimal wind turbine rotor speed. Therefore, the power fluctuation......Wind power fluctuation raises the security concern of grid frequency deviation, especially for an isolated power system. Thus, better control methodology needs to be developed to smooth the fluctuation without excessive spillage. Based on an actual industrial power system, this paper proposes...

  10. Controller Design of DFIG Based Wind Turbine by Using Evolutionary Soft Computational Techniques

    Directory of Open Access Journals (Sweden)

    O. P. Bharti

    2017-06-01

    Full Text Available This manuscript illustrates the controller design for a doubly fed induction generator based variable speed wind turbine by using a bioinspired scheme. This methodology is based on exploiting two proficient swarm intelligence based evolutionary soft computational procedures. The particle swarm optimization (PSO and bacterial foraging optimization (BFO techniques are employed to design the controller intended for small damping plant of the DFIG. Wind energy overview and DFIG operating principle along with the equivalent circuit model is adequately discussed in this paper. The controller design for DFIG based WECS using PSO and BFO are described comparatively in detail. The responses of the DFIG system regarding terminal voltage, current, active-reactive power, and DC-Link voltage have slightly improved with the evolutionary soft computational procedure. Lastly, the obtained output is equated with a standard technique for performance improvement of DFIG based wind energy conversion system.

  11. Power-Smoothing Scheme of a DFIG Using the Adaptive Gain Depending on the Rotor Speed and Frequency Deviation

    DEFF Research Database (Denmark)

    Lee, Hyewon; Hwang, Min; Muljadi, Eduard

    2017-01-01

    In an electric power grid that has a high penetration level of wind, the power fluctuation of a large-scale wind power plant (WPP) caused by varying wind speeds deteriorates the system frequency regulation. This paper proposes a power-smoothing scheme of a doubly-fed induction generator (DFIG...... demonstrate that the proposed scheme significantly lessens the output power fluctuation of a WPP under various scenarios by modifying the gain with the rotor speed and frequency deviation, and thereby it can regulate the frequency deviation within a narrow range.......) that significantly mitigates the system frequency fluctuation while preventing over-deceleration of the rotor speed. The proposed scheme employs an additional control loop relying on the system frequency deviation that operates in combination with the maximum power point tracking control loop. To improve the power...

  12. Off-shore wind power plant modelling precision and efficiency in electromagnetic transient simulation programs

    Energy Technology Data Exchange (ETDEWEB)

    Karaagac, U.; Saad, H.; Mahseredjian, J. [Ecole Polytechnique de Montreal, Montreal, QC (Canada); Jensen, S.; Cai, L. [REpower Systems AG, Hamburg (Germany)

    2012-07-01

    The large number of switching elements in the modular multilevel converter (MMC) is a challenging problem for modeling the MMC-HVDC systems in electromagnetic transient type (EMT-type) programs. The modeling complexity increases even further when MMC-HVDC systems are used to integrate offshore wind farms (OWFs) with power electronics based wind energy converters, such as doubly-fed induction generators (DFIGs). This paper compares the computational performances of various combinations of MMC-HVDC and OWF models. Practical onshore ac fault scenarios are simulated for an OWF composed of DFIG type wind turbines and connected to a practical ac grid through a point-to-point MMC-HVDC system. (orig.)

  13. Improved DFIG Capability during Asymmetrical Grid Faults

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede

    2015-01-01

    In the wind power application, different asymmetrical types of the grid fault can be categorized after the Y/d transformer, and the positive and negative components of a single-phase fault, phase-to-phase fault, and two-phase fault can be summarized. Due to the newly introduced negative and even...... the natural component of the Doubly-Fed Induction Generator (DFIG) stator flux during the fault period, their effects on the rotor voltage can be investigated. It is concluded that the phase-to-phase fault has the worst scenario due to its highest introduction of the negative stator flux. Afterwards......, the capability of a 2 MW DFIG to ride through asymmetrical grid faults can be estimated at the existing design of the power electronics converter. Finally, a control scheme aimed to improve the DFIG capability is proposed and the simulation results validate its feasibility....

  14. Power Quality of Grid-Connected Wind Turbines with DFIG and Their Interaction with the Grid

    DEFF Research Database (Denmark)

    Sun, Tao

    quality issues of grid-connected wind turbines and the interaction between wind turbines and the grid. The specific goal of the research has been to investigate flicker emission and mitigation of grid-connected wind turbines with doubly fed induction generators (DFIG) during continuous operation...... measures are proposed to mitigate the flicker levels produced by grid-connected wind turbines with DFIG, respectively by wind turbine output reactive power control and using STATCOM. Simulation results demonstrate that these two measures are effective for flicker mitigation regardless of mean wind speed....... To evaluate the flicker levels produced by grid-connected wind turbines with DFIG, a flickermeter model is developed according to the IEC standard IEC 61000-4-15, which simulates the response of the lamp-eye-brain chain and provides on-line statistical analysis ofthe flicker signal and the final results...

  15. Impedance characteristics of DFIGs considering the impacts of DFIG numbers and its application on SSR analysis

    Science.gov (United States)

    You, J. J.; Ning, W. Y.; Jiang, H.; Dong, Y. X.; Liu, H.; Li, Y.

    2017-05-01

    Sub-synchronous resonance (SSR) occurred in the power system with both Doubly Fed Induction Generators (DFIGs) and series-compensated lines. There have been several papers focusing on the analysis of such SSR phenomenon. To the authors’ knowledge, the impacts of DFIG numbers are seldom considered in existing papers. In this paper, the impedance characteristics of DFIGs under different numbers are analyzed. Then the relationship between DFIG numbers and SSR characteristics is discussed. The contributions to be included in the paper are as following: 1) the impedance of N DFIGs is roughly equal to 1/N of the impedance of one DFIG. 2) The SSR risk of system is related with both the numbers of DFIGs and the parameters of the series-compensated lines.

  16. Modeling Induction Motor Imbalances

    DEFF Research Database (Denmark)

    Armah, Kabenla; Jouffroy, Jerome; Duggen, Lars

    2016-01-01

    This paper gives a study into the development of a generalized model for a three-phase induction motor that offers flexibility of simulating balanced and unbalanced parameter scenarios. By analyzing the interaction of forces within the motor, we achieve our main objective of deriving the system d...

  17. High current induction linacs

    International Nuclear Information System (INIS)

    Barletta, W.; Faltens, A.; Henestroza, E.; Lee, E.

    1994-07-01

    Induction linacs are among the most powerful accelerators in existence. They have accelerated electron bunches of several kiloamperes, and are being investigated as drivers for heavy ion driven inertial confinement fusion (HIF), which requires peak beam currents of kiloamperes and average beam powers of some tens of megawatts. The requirement for waste transmutation with an 800 MeV proton or deuteron beam with an average current of 50 mA and an average power of 40 MW lies midway between the electron machines and the heavy ion machines in overall difficulty. Much of the technology and understanding of beam physics carries over from the previous machines to the new requirements. The induction linac allows use of a very large beam aperture, which may turn out to be crucial to reducing beam loss and machine activation from the beam halo. The major issues addressed here are transport of high intensity beams, availability of sources, efficiency of acceleration, and the state of the needed technology for the waste treatment application. Because of the transformer-like action of an induction core and the accompanying magnetizing current, induction linacs make the most economic sense and have the highest efficiencies with large beam currents. Based on present understanding of beam transport limits, induction core magnetizing current requirements, and pulse modulators, the efficiencies could be very high. The study of beam transport at high intensities has been the major activity of the HIF community. Beam transport and sources are limiting at low energies but are not significant constraints at the higher energies. As will be shown, the proton beams will be space-charge-dominated, for which the emittance has only a minor effect on the overall beam diameter but does determine the density falloff at the beam edge

  18. Compound induction electric rotating machine

    Energy Technology Data Exchange (ETDEWEB)

    Decesare, D

    1987-07-28

    The present invention generally relates to dynamo-electric machines cabable of operating in a generator mode or in a motor mode and more specifically, to increased efficiency compound interaction AC and/or DC dynamo-electric machines. This patent describes such a machine having a distributed armature winding in a cylindrical rotor wound to form axial and substantially radial winding portions and including permanent and/or electromagnets to couple magnetic flux into the peripheral or circumferential surface of the rotor, and to provide interaction between a magnetic field formed beyond the rotor axial surfaces and the rotor to thereby enhance the total induction of flux into the rotor for improved, more efficient operation. 28 figs.,

  19. Inductive Communication System Design Summary

    Science.gov (United States)

    1978-09-01

    The report documents the experience obtained during the design and development of the Inductive Communications System used in the Morgantown People Mover. The Inductive Communications System is used to provide wayside-to-vehicle and vehicle-to-waysid...

  20. Glass manufacturing through induction

    International Nuclear Information System (INIS)

    Boen, R.; Paya, B.; Roscini, M.; Fautrelle, Y.; Tuaz, F.; Delage, D.

    1991-01-01

    Oxides and glasses are electrical and thermal insulators, but show the characteristic of being weakly conductors of electricity when they are melt. It is then possible to heat them through HF induction. This interesting property allows the development of a melting process in cold crucible induction furnace. The process is being studied and developed by a consortium made up of CFEI, CEA Marcoule, ELECTRICITE DE FRANCE and MADYLAM laboratory. The studies include 2 parts: a) One experimental part to develop the technology and research for satisfying configurations, through a small size platform (10 to 30 kg/h). The long run continuous pouring melting tests made on different kinds of glass allow to go-on with industrial range units. b) One theoretical part to understand the magneto-thermo-hydraulic phenomenon hardly in relation with the heavy dependence of the physical characteristics (electrical and heat conductivities, viscosity) according to temperature. 6 refs., 4 figs [fr