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Sample records for voltage charge control

  1. Adaptive coordinated control of engine speed and battery charging voltage

    Institute of Scientific and Technical Information of China (English)

    Jiangyan ZHANG; Xiaohong JIAO

    2008-01-01

    In this paper, the control problem of auxiliary power unit (APU) for hybrid electric vehicles is investigated. An adaptive controller is provided to achieve the coordinated control between the engine speed and the battery charging voltage. The proposed adaptive coordinated control laws for the throttle angle of the engine and the voltage of the power-converter can guarantee not only the asymptotic tracking performance of the engine speed and the regulation of the battery charging voltage, but also the robust stability of the closed loop system under external load changes. Simulation results are given to verify the performance of the proposed adaptive controller.

  2. Characterisation of charge voltage of lead-acid batteries: application to the charge control strategy in photovoltaic systems

    Energy Technology Data Exchange (ETDEWEB)

    Vela, N. [CIEMAT-DER, Madrid (Spain). Laboratorio de Energia Solar Fotovoltaica; Aguilera, J. [Universidad de Jaen (Spain). Escuela Politecnica Superior

    2006-12-15

    In stand-alone photovoltaic (PV) systems, charge controllers prevent excessive battery overcharge by interrupting or limiting the current flow from the PV array to the battery when the battery becomes fully charged. Charge regulation is most often accomplished by limiting the battery voltage to a predetermined value or cut-off voltage, higher than the gassing voltage. These regulation voltages are dependent on the temperature and battery charge current. An adequate selection of overcharge cut-off voltage for each battery type and operating conditions would maintain the highest battery state of charge without causing significant overcharge thus improving battery performance and reliability. To perform this work, a sample of nine different lead-acid batteries, typically used in stand-alone PV systems including vented and sealed batteries with 2 V cells and monoblock configurations have been selected. This paper presents simple mathematical expressions fitting two charge characteristic voltages: the gassing voltage (V{sub g}) and the end-of charge voltage (V{sub fc}) as function of charge current and temperature for the tested batteries. With these expressions, we have calculated V{sub g} and V{sub fc} at different current rates. An analysis of the different values obtained is presented here focusing in the implication in control strategies of batteries in stand-alone PV systems. (author)

  3. A Uniform Voltage Gain Control for Alignment Robustness in Wireless EV Charging

    Directory of Open Access Journals (Sweden)

    Yabiao Gao

    2015-08-01

    Full Text Available The efficiency of wireless power transfer is sensitive to the horizontal and vertical distances between the transmitter and receiver coils due to the magnetic coupling change. To address the output voltage variation and efficiency drop caused by misalignment, a uniform voltage gain frequency control is implemented to improve the power delivery and efficiency of wireless power transfer under misalignment. The frequency is tuned according to the amplitude and phase-frequency characteristics of coupling variations in order to maintain a uniform output voltage in the receiver coil. Experimental comparison of three control methods, including fixed frequency control, resonant frequency control, and the proposed uniform gain control was conducted and demonstrated that the uniform voltage gain control is the most robust method for managing misalignment in wireless charging applications.

  4. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  5. Charging System of ECRH High-Voltage Power Supply and its Control System

    Institute of Scientific and Technical Information of China (English)

    胡国富; 丁同海; 刘保华; 姜书方

    2003-01-01

    High-voltage power supply (HVPS) of Electron Cyclotron Resonance Heating(ECRH) for HT-7 and HT-7U is presently being constructed. The high voltage (100 kV) en-ergy of HVPS is stored in the capacitor banks, and they can power one or two gyrotrons. All theoperation of the charging system will be done by the control system, where the field signals areinterfaced to programmable logic controller (PLC). The use of PLC not only simplifies the controlsystem, but also enhances the reliability. The software written by using configuration softwareinstalled in the master computer allows for remote and multiple operator control, and the statusand data information is also remotely available.

  6. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  7. Performance of Li-Ion Cells Under Battery Voltage Charge Control

    Science.gov (United States)

    Vaidyanathan, Hari; Rao, Gopalakrishna M.

    2002-01-01

    Li-ion cells manufactured by YTP, SAFT, and MSA have completed 6714, 6226, and 3441 cycles, respectively. An increase in the charge voltage limit was required in all cases to maintain the discharge voltage. SAFT and MSA cells were capable of cycling at -10 C and 0 C with an increase in the charge voltage limit, whereas Yardney cells could not be cycled. Reconditioning improved the discharge voltage of SAFT and MSA cells; it is important to note that the effect has been temporary as in Ni-H and Ni-Cd batteries. It was demonstrated that the charge operation with VT clamp at battery rather than at cell level is feasible. Continuation of testing depends on the health of the cells and on the funding situation.

  8. A Decentralized Control Method for Distributed Generations in an Islanded DC Microgrid Considering Voltage Drop Compensation and Durable State of Charge

    Directory of Open Access Journals (Sweden)

    Chul-Sang Hwang

    2016-12-01

    Full Text Available This paper presents a decentralized control method for distributed generations (DGs in an islanded direct current (DC microgrid. In most typical DC microgrids, a decentralized control method is based on a voltage droop control method. However, the grid voltage differs from node to node due to line voltage drop, and hence the power sharing ratio among DGs cannot be matched with as desired value. Especially in an islanded DC microgrid including an energy storage system as a voltage source, it is difficult for DGs to maintain the charge state of the ESS in a decentralized way. To overcome this problem, state of charge (SOC-voltage droop control is applied to the ESS. By using the proposed droop method, the SOC information can be assigned to the grid voltage, and hence the other DGs are able to support the SOC in a decentralized way. For DGs to enhance the accuracy of the SOC estimation, voltage drop is compensated for based on forecasting data and line impedance data. The simulation is modeled and implemented using Power System Computer Aided Design/Electromagnetic Transients for DC (PSCAD/EMTDC, version 4.2, Winnipeg, Manitoba, Canada and the simulation results show that the capability to maintain SOC as well as the system voltage profile are improved by using the proposed method.

  9. Voltage Scheduling Droop Control for State-of-Charge Balance of Distributed Energy Storage in DC Microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Dragicevic, Tomislav; Aldana, Nelson Leonardo Diaz

    2014-01-01

    the State-of-Charge balance. In this paper, a new droop method based on voltage scheduling for State-of-Charge balance is proposed to keep the SoC balance for the energy storage units. The proposed method has the advantage of avoiding the stability problem existed in traditional methods based on droop gain...... scheduling. Simulation experiment is taken in Matlab on a DC microgrid with two distributed energy storage units. The simulation results show that the proposed method has successfully achieved SoC balance during the load changes while maintaining the DC bus voltage within the allowable range....

  10. DC Fast-Charging Stations for EVs Controlled by a Local Battery Storage in Low Voltage Grids

    DEFF Research Database (Denmark)

    Gjelaj, Marjan; Træholt, Chresten; Hashemi Toghroljerdi, Seyedmostafa

    2017-01-01

    Electric Vehicles (EVs) are representing a great opportunity for major car manufacturers to invest resources in new technologies in order to support sustainable transportation and the reduction of 퐂퐎ퟐ emissions, in particular in the metropolitan areas. In recent years, the increasing penetration...... is equipped with a bidirectional AC/DC converter for feeding power back to the grid, two lithium batteries and a DC/DC converter. The proposed solution decreases the charging time of EVs and facilitates the integration of fast chargers in existing low voltage (LV) grids. The charging station can also be used...

  11. Modular Battery Charge Controller

    Science.gov (United States)

    Button, Robert; Gonzalez, Marcelo

    2009-01-01

    A new approach to masterless, distributed, digital-charge control for batteries requiring charge control has been developed and implemented. This approach is required in battery chemistries that need cell-level charge control for safety and is characterized by the use of one controller per cell, resulting in redundant sensors for critical components, such as voltage, temperature, and current. The charge controllers in a given battery interact in a masterless fashion for the purpose of cell balancing, charge control, and state-of-charge estimation. This makes the battery system invariably fault-tolerant. The solution to the single-fault failure, due to the use of a single charge controller (CC), was solved by implementing one CC per cell and linking them via an isolated communication bus [e.g., controller area network (CAN)] in a masterless fashion so that the failure of one or more CCs will not impact the remaining functional CCs. Each micro-controller-based CC digitizes the cell voltage (V(sub cell)), two cell temperatures, and the voltage across the switch (V); the latter variable is used in conjunction with V(sub cell) to estimate the bypass current for a given bypass resistor. Furthermore, CC1 digitizes the battery current (I1) and battery voltage (V(sub batt) and CC5 digitizes a second battery current (I2). As a result, redundant readings are taken for temperature, battery current, and battery voltage through the summation of the individual cell voltages given that each CC knows the voltage of the other cells. For the purpose of cell balancing, each CC periodically and independently transmits its cell voltage and stores the received cell voltage of the other cells in an array. The position in the array depends on the identifier (ID) of the transmitting CC. After eight cell voltage receptions, the array is checked to see if one or more cells did not transmit. If one or more transmissions are missing, the missing cell(s) is (are) eliminated from cell

  12. Active battery charge equalization with voltage controlled vertical buck-boost switching cells%电压控制Buck-Boost电池充电均衡器

    Institute of Scientific and Technical Information of China (English)

    谢莉; 蒋伟

    2015-01-01

    本文研究了储能设备的均衡充电方法。采用垂直 Buck-Boost 电路作为均衡器的基本交换单元。在不同的负载条件下,用状态空间平均法和小信号分析法获得对应的开关单元模型。通过电压控制均衡方案,利用电压环补偿设备端电压,电流内环使得电荷定向移动。实验结果表明,所提出的均衡器能实现电荷最快移动并能有效地收敛到零电压差,本地控制器能快速、准确地跟踪参考值。%This paper investigates the active charge equalization method for energy storage devices. The vertical buck-boost circuit is used as the basic switching cell of this equalizer. By applying state-space averaging and small signal analysis, the model of the switching cell is obtained under different load condition. A voltage controlled equalization scheme is presented, which is featured with voltage loop to equalize the terminal voltage and inner current loop for charge shuttling. The simulation and experimental results indicate that the proposed equalizer can effectively converge to zero voltage difference condition by offering a maximized charge shuttling effort, and the local controller can react fast and precisely to the reference command.

  13. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    . An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  14. Space charge accumulation in polymeric high voltage DC cable systems

    NARCIS (Netherlands)

    Bodega, R.

    2006-01-01

    One of the intrinsic properties of the polymeric high voltage (HV) direct current (DC) cable insulation is the accumulation of electrostatic charges. Accumulated charges distort the initial Laplacian distribution of the electric field, leading to a local field enhancement that may cause insulation d

  15. Voltage charging enhances ionic conductivity in gold nanotube membranes.

    Science.gov (United States)

    Gao, Peng; Martin, Charles R

    2014-08-26

    Ionically conductive membranes are used in many electrochemical processes and devices, including batteries, fuel cells, and electrolyzers. In all such applications, it is advantageous to use membranes with high ionic conductivity because membrane resistance causes a voltage loss suffered by the cell. We describe here a method for enhancing ionic conductivity in membranes containing small diameter (4 nm) gold nanotubes. This entails making the gold nanotube membrane the working electrode in an electrochemical cell and applying a voltage to the membrane. We show here that voltage charging in this way can increase membrane ionic conductivity by over an order of magnitude. When expressed in terms of the ionic conductivity of the electrolyte, κ, within an individual voltage-charged tube, the most negative applied voltage yielded a κ comparable to that of 1 M aqueous KCl, over 2 orders of magnitude higher than κ of the 0.01 M KCl solution contacting the membrane.

  16. A compact control system to achieve stable voltage and low jitter trigger for repetitive intense electron-beam accelerator based on resonant charging

    Science.gov (United States)

    Qiu, Yongfeng; Liu, Jinliang; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao

    2017-08-01

    A compact control system based on Delphi and Field Programmable Gate Array(FPGA) is developed for a repetitive intense electron-beam accelerator(IEBA), whose output power is 10GW and pulse duration is 160ns. The system uses both hardware and software solutions. It comprises a host computer, a communication module and a main control unit. A device independent applications programming interface, devised using Delphi, is installed on the host computer. Stability theory of voltage in repetitive mode is analyzed and a detailed overview of the hardware and software configuration is presented. High voltage experiment showed that the control system fulfilled the requests of remote operation and data-acquisition. The control system based on a time-sequence control method is used to keep constant of the voltage of the primary capacitor in every shot, which ensured the stable and reliable operation of the electron beam accelerator in the repetitive mode during the experiment. Compared with the former control system based on Labview and PIC micro-controller developed in our laboratory, the present one is more compact, and with higher precision in the time dimension. It is particularly useful for automatic control of IEBA in the high power microwave effects research experiments where pulse-to-pulse reproducibility is required.

  17. Automated Voltage Control in LHCb

    CERN Document Server

    Granado Cardoso, L; Jacobsson, R

    2011-01-01

    LHCb is one of the 4 LHC experiments. In order to ensure the safety of the detector and to maximize efficiency, LHCb needs to coordinate its own operations, in particular the voltage configuration of the different subdetectors, according to the accelerator status. A control software has been developed for this purpose, based on the Finite State Machine toolkit and the SCADA system used for control throughout LHCb (and the other LHC experiments). This software permits to efficiently drive both the Low Voltage (LV) and High Voltage (HV) systems of the 10 different sub-detectors that constitute LHCb, setting each sub-system to the required voltage (easily configurable at run-time) based on the accelerator state. The control software is also responsible for monitoring the state of the Sub-detector voltages and adding it to the event data in the form of status-bits. Safe and yet flexible operation of the LHCb detector has been obtained and automatic actions, triggered by the state changes of the ...

  18. Effects of dielectric charging on the output voltage of a capacitive accelerometer

    Science.gov (United States)

    Qu, Hao; Yu, Huijun; Zhou, Wu; Peng, Bei; Peng, Peng; He, Xiaoping

    2016-11-01

    Output voltage drifting observed in one typical capacitive microelectromechanical system (MEMS) accelerometer is discussed in this paper. Dielectric charging effect is located as one of the major determinants of this phenomenon through a combination of experimental and theoretical studies. A theoretical model for the electromechanical effects of the dielectric surface charges within the electrode gap is established to analyze the dielectric charge effect on the output voltage. Observations of output voltage drift against time are fitted to this model in order to estimate the possible dielectric layer thickness. Meanwhile, Auger electron spectroscopy is carried out to analyze the electrode surface material composition and confirms a mixture layer of dielectric SiO2 and Si with a thickness about 5 nm, which is very close to the model estimation. In addition, observation of time-varing output drift in the variable bias voltage experiment indicates the movement of dielectric charge can be controlled by the applied electric field.

  19. Moderately nonlinear diffuse-charge dynamics under an ac voltage

    Science.gov (United States)

    Stout, Robert F.; Khair, Aditya S.

    2015-09-01

    The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of Vo/(kBT /e ) , where Vo is the amplitude of the driving voltage and kBT /e is the thermal voltage with kB as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D /λDL , where D is the ion diffusivity, λD is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O (Vo3) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in Vo. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing Vo. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.

  20. High Voltage Frame and Differential Charging Observed on a Geosynchronous Spacecraft

    Science.gov (United States)

    Dichter, B. K.; Ray, K. P.; Gussenhoven, M. S.; Holeman, E. G.; Delorey, D. E.; Mullen, E. G.

    1998-11-01

    We have studied the frequency and levels of frame and differential charging on a geosynchronous satellite since August of 1995. High voltage differential charging was measured with Surface Potential Monitors (SPM) for two typical spacecraft surfaces (Kapton and Astroquartz). Frame charging was determined using an ion electrostatic analyzer. In addition, the integrated electron population between 20 and 50 keV was also measured. The statistical study includes frame and differential charging over a three-year period. We also address the ability to reduce the charging levels using an autonomous Charge Control System (CCS). The CCS releases a Xenon plasma to help provide current balance when high fluxes of electrons impinge on the spacecraft. A case study of a charging event will focus on identifying the population responsible for charging, current balance issues and differences in charging levels as observed by the SPM and the ion analyzer.

  1. Deployment of low-voltage regulator considering existing voltage control in medium-voltage distribution systems

    Directory of Open Access Journals (Sweden)

    Hiroshi Kikusato

    2016-01-01

    Full Text Available Many photovoltaic (PV systems have been installed in distribution systems. This installation complicates the maintenance of all voltages within the appropriate range in all low-voltage distribution systems (LVDSs because the trends in voltage fluctuation differ in each LVDS. The installation of a low-voltage regulator (LVR that can accordingly control the voltage in each LVDS has been studied as a solution to this problem. Voltage control in a medium-voltage distribution system must be considered to study the deployment of LVRs. In this study, we installed LVRs in the LVDSs in which the existing voltage-control scheme cannot prevent voltage deviation and performed a numerical simulation by using a distribution system model with PV to evaluate the deployment of the LVRs.

  2. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... analysis, which is simple for computation and requires moderate automation and communication infrastructure. The proposed method is suitable for a hierarchical control structure where a supervisory controller has the provision to adapt the settings of local PV inverter controllers for overall system...

  3. Voltage-controlled photonic oscillator.

    Science.gov (United States)

    Savchenkov, A A; Ilchenko, V S; Liang, W; Eliyahu, D; Matsko, A B; Seidel, D; Maleki, L

    2010-05-15

    We report the development and demonstration of an X-band voltage-controlled photonic oscillator based on a whispering gallery mode resonator made of an electro-optic crystalline material. The oscillator has good spectral purity and wide, agile, linear tunability. We have modified the existing theoretical model of the opto-electronic oscillator to describe the performance of our tunable oscillator and have found a good agreement between the theoretical predictions and the measurement results. We show that the device is promising for higher-frequency applications where high-performance tunable oscillators with wide tunability do not exist.

  4. Analysis and Comparison of Voltage Dependent Charging Strategies for Single-Phase Electric Vehicles in an Unbalanced Danish Distribution Grid

    DEFF Research Database (Denmark)

    Álvarez, Jorge Nájera; Knezovic, Katarina; Marinelli, Mattia

    2016-01-01

    This paper studies four voltage dependent solutions for modulating the charging of multiple Electric Vehicles (EVs) in a real Danish network. Uncontrolled EV charging, especially in grid with high EV penetration, can result in overloaded lines and transformers, low-voltages and other performance......-in on phases with lower voltages are constrained during the charging period. In order to solve instability issues which may occur due to lack of communication between the controllers, several improvements are applied to the aforementioned droop control. Simulation results demonstrate the performance...

  5. A Charge Controller Design For Solar Power System

    Directory of Open Access Journals (Sweden)

    Nandar Oo

    2015-08-01

    Full Text Available This paper presents the solar charge controller circuit for controlling the overcharging and discharging from solar panel. This circuit regulates the charging of the battery in a solar system by monitoring battery voltage and switching the solar or other power source off when the battery reaches a preset voltage. This circuit is low voltages disconnect circuit. A charge controller circuit can increase battery life by preventing over-charging which can cause loss of electrolyte. The flow chart is also provided.

  6. Piezo Voltage Controlled Planar Hall Effect Devices

    OpenAIRE

    Bao Zhang; Kang-Kang Meng; Mei-Yin Yang; Edmonds, K. W.; Hao Zhang; Kai-Ming Cai; Yu Sheng; Nan Zhang; Yang Ji; Jian-Hua Zhao; Hou-Zhi Zheng; Kai-You Wang

    2015-01-01

    The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the pie...

  7. Electric vehicle battery charging controller

    DEFF Research Database (Denmark)

    2016-01-01

    to a battery management system in the electric vehicle to charge a battery therein, a first communication unit for receiving a charging message via a communication network, and a control unit for controlling a charging current provided from the charge source to the electric vehicle, the controlling at least...

  8. Piezo Voltage Controlled Planar Hall Effect Devices

    Science.gov (United States)

    Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K. W.; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You

    2016-06-01

    The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.

  9. Piezo Voltage Controlled Planar Hall Effect Devices.

    Science.gov (United States)

    Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You

    2016-06-22

    The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.

  10. 50V All-PMOS Charge Pumps Using Low-Voltage Capacitors

    KAUST Repository

    Emira, Ahmed

    2012-10-06

    In this work, two high-voltage charge pumps are introduced. In order to minimize the area of the pumping capacitors, which dominates the overall area of the charge pump, high density capacitors have been utilized. Nonetheless, these high density capacitors suffer from low breakdown voltage which is not compatible with the targeted high voltage application. To circumvent the breakdown limitation, a special clocking scheme is used to limit the maximum voltage across any pumping capacitor. The two charge pump circuits were fabricated in a 0:6m CMOS technology with poly0-poly1 capacitors. The output voltage of the two charge pumps reached 42:8V and 51V while the voltage across any capacitor did not exceed the value of the input voltage. Compared to other designs reported in the literature, the proposed charge pump provides the highest output voltage which makes it more suitable for tuning MEMS devices.

  11. Frequency-controlled voltage regulator

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Converting input ac to higher frequency reduce size and weight and makes possible unique kind of regulation. Since conversion frequency is above range of human hearing, supply generated on audible noise. It also exploits highfrequency conversion features to regulate its output voltage in novel way. Circuit is inherently short-circuit proof.

  12. Microprocessor-controlled, programmable ramp voltage generator

    Energy Technology Data Exchange (ETDEWEB)

    Hopwood, J.

    1978-11-01

    A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds.

  13. Voltage-Controlled Floating Resistor Using DDCC

    Directory of Open Access Journals (Sweden)

    M. Kumngern

    2011-04-01

    Full Text Available This paper presents a new simple configuration to realize the voltage-controlled floating resistor, which is suitable for integrated circuit implementation. The proposed resistor is composed of three main components: MOS transistor operating in the non-saturation region, DDCC, and MOS voltage divider. The MOS transistor operating in the non-saturation region is used to configure a floating linear resistor. The DDCC and the MOS transistor voltage divider are used for canceling the nonlinear component term of MOS transistor in the non-saturation region to obtain a linear current/voltage relationship. The DDCC is employed to provide a simple summer of the circuit. This circuit offers an ease for realizing the voltage divider circuit and the temperature effect that includes in term of threshold voltage can be compensated. The proposed configuration employs only 16 MOS transistors. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.

  14. Surface-charge accumulation effects on open-circuit voltage in organic solar cells based on photoinduced impedance analysis.

    Science.gov (United States)

    Zang, Huidong; Hsiao, Yu-Che; Hu, Bin

    2014-03-14

    The accumulation of dissociated charge carriers plays an important role in reducing the loss occurring in organic solar cells. We find from light-assisted capacitance measurements that the charge accumulation inevitably occurred at the electrode and photovoltaic layer interface for bulk-heterojunction ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al solar cells. Our results indicate, for the first time through impedance measurements, that the charge accumulation exists at the anode side of the device, and more importantly, we successfully identify the type of charge accumulated. Further study shows that the charge accumulation can significantly affect open circuit voltage and short circuit current. As a result, our experimental results from light assisted capacitance measurements provide a new understanding of the loss in open-circuit voltage and short-circuit photocurrent based on charge accumulation. Clearly, controlling charge accumulation presents a new mechanism to improve the photovoltaic performance of organic solar cells.

  15. Coordinated Voltage Control of Active Distribution Network

    Directory of Open Access Journals (Sweden)

    Xie Jiang

    2016-01-01

    Full Text Available This paper presents a centralized coordinated voltage control method for active distribution network to solve off-limit problem of voltage after incorporation of distributed generation (DG. The proposed method consists of two parts, it coordinated primal-dual interior point method-based voltage regulation schemes of DG reactive powers and capacitors with centralized on-load tap changer (OLTC controlling method which utilizes system’s maximum and minimum voltages, to improve the qualified rate of voltage and reduce the operation numbers of OLTC. The proposed coordination has considered the cost of capacitors. The method is tested using a radial edited IEEE-33 nodes distribution network which is modelled using MATLAB.

  16. Charged particle dynamics and process control in capacitive RF discharges driven by tailored voltage waveforms in mixtures of Argon and CF4

    Science.gov (United States)

    Brandt, Steven; Donko, Zoltan; Schulze, Julian

    2016-09-01

    The electron power absorption dynamics and the Electrical Asymmetry Effect (EAE) are computationally investigated for Argon-CF4 gas mixtures in geometrically symmetric capacitively coupled plasmas. Simulations are performed for both single- and triple-frequency tailored voltage waveforms at 20 and 60 Pa, using a fundamental frequency of 13.56 MHz and its consecutive harmonics. The results at 60 Pa show electron power absorption mode transitions between the Drift-Ambipolar (DA) mode and the α-mode induced by varying the admixture of Ar to CF4, which leads to a change of the plasma chemistry. In the triple-frequency cases small argon admixtures (of the order of 10%) strongly affect the electron power absorption dynamics and the symmetry of the discharge. The change of the electrical generation of a DC self-bias via the EAE, the ion flux-energy distribution functions of different ion species at the electrodes, and the excitation of resonance effects are studied as a function of the mixing ratio of these two gases. The results are expected to be highly relevant for plasma processing, where such gas mixtures are often used.

  17. Voltage controlled spintronics device for logic applications.

    Energy Technology Data Exchange (ETDEWEB)

    Bader, S. D.; You, C.-Y.

    1999-09-03

    We consider logic device concepts based on our previously proposed spintronics device element whose magnetization orientation is controlled by application of a bias voltage instead of a magnetic field. The basic building block is the voltage-controlled rotation (VCR) element that consists of a four-layer structure--two ferromagnetic layers separated by both nanometer-thick insulator and metallic spacer layers. The interlayer exchange coupling between the two ferromagnetic layers oscillates as a function of applied voltage. We illustrate transistor-like concepts and re-programmable logic gates based on VCR elements.

  18. Congestion control in charging of electric vehicles

    CERN Document Server

    Carvalho, Rui; Gibbens, Richard; Kelly, Frank

    2015-01-01

    The increasing penetration of electric vehicles over the coming decades, taken together with the high cost to upgrade local distribution networks, and consumer demand for home charging, suggest that managing congestion on low voltage networks will be a crucial component of the electric vehicle revolution and the move away from fossil fuels in transportation. Here, we model the max-flow and proportional fairness protocols for the control of congestion caused by a fleet of vehicles charging on distribution networks. We analyse the inequality in the charging times as the vehicle arrival rate increases, and show that charging times are considerably more uneven in max-flow than in proportional fairness. We also analyse the onset of instability, and find that the critical arrival rate is indistinguishable between the two protocols.

  19. THEORETICAL ANALYSIS OF CHARGE ACCUMULATION ON INSULATOR SURFACE UNDER IMPULSE VOLTAGE IN A GAS INSULATED SWITCHGEAR

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective To investigate the process and mechanism of insulator surface charge accumulation under impulse voltage, a dynamic equation was established for describing the relationship between surface charge density and applied voltage. Results The established equation is more generalized in comparison with that given by other previous investigators. Constants A, B for typical electrodes used in the present equation are specified. The process and mechanism of surface charge accumulation under impulse voltage are studied and the factors that influence surface charge accumulation discussed. Conclusion The present theoretical studies help to explain why surface charging can be accomplished instantly under impulse voltage, and determine the factors influencing surface charge accumulation. The findings confirmed some surface charging phenomena observed in GIS by some previous investigators.

  20. Voltage control of DC islanded microgrids

    DEFF Research Database (Denmark)

    Tucci, Michele; Riverso, Stefano; Quintero, Juan Carlos Vasquez

    2015-01-01

    We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the Point of Common Coupling (PCC) of the correspond......We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the Point of Common Coupling (PCC...

  1. Voltage-controlled domain wall traps in ferromagnetic nanowires

    Science.gov (United States)

    Bauer, Uwe; Emori, Satoru; Beach, Geoffrey S. D.

    2013-06-01

    Electrical control of magnetism has the potential to bring about revolutionary new spintronic devices, many of which rely on efficient manipulation of magnetic domain walls in ferromagnetic nanowires. Recently, it has been shown that voltage-induced charge accumulation at a metal-oxide interface can influence domain wall motion in ultrathin metallic ferromagnets, but the effects have been relatively modest and limited to the slow, thermally activated regime. Here we show that a voltage can generate non-volatile switching of magnetic properties at the nanoscale by modulating interfacial chemistry rather than charge density. Using a solid-state ionic conductor as a gate dielectric, we generate unprecedentedly strong voltage-controlled domain wall traps that function as non-volatile, electrically programmable and switchable pinning sites. Pinning strengths of at least 650 Oe can be readily achieved, enough to bring to a standstill domain walls travelling at speeds of at least ~20 m s-1. We exploit this new magneto-ionic effect to demonstrate a prototype non-volatile memory device in which voltage-controlled domain wall traps facilitate electrical bit selection in a magnetic nanowire register.

  2. Voltage-Sensitive Load Controllers for Voltage Regulation and Increased Load Factor in Distribution Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Østergaard, Jacob

    2014-01-01

    consumption which can be mapped to temperature setpoint offsets of thermostat controlled loads. In networks where a lower voltage level corresponds to high system load (and vice versa), this controller acts to regulate voltage and increase the load factor. Simulations are conducted on low- and medium-voltage......This paper presents a novel controller design for controlling appliances based on local measurements of voltage. The controller finds the normalized voltage deviation accounting for the sensitivity of voltage measurements to appliance state. The controller produces a signal indicating desired power...... distribution systems with residential loads including voltage-sensitive water heaters. In low-voltage systems, the results of the simulations show the controller to be effective at reducing the extremes of voltage and increasing the load factor while respecting end-use temperature constraints. In medium-voltage...

  3. Multiagent voltage and reactive power control system

    Directory of Open Access Journals (Sweden)

    I. Arkhipov

    2014-12-01

    Full Text Available This paper is devoted to the research of multiagent voltage and reactive power control system development. The prototype of the system has been developed by R&D Center at FGC UES (Russia. The control system architecture is based on the innovative multiagent system theory application that leads to the achievement of several significant advantages (in comparison to traditional control systems implementation such as control system efficiency enhancement, control system survivability and cyber security.

  4. A new method for compensation of the effect of charging transformer's leakage inductance on PFN voltage regulation in Klystron pulse modulators

    Science.gov (United States)

    Patel, Akhil; Kale, Umesh; Shrivastava, Purushottam

    2017-04-01

    The Line type modulators have been widely used to generate high voltage rectangular pulses to power the klystron for high power RF generation. In Line type modulator, the Pulse Forming Network (PFN) which is a cascade combination of lumped capacitors and inductors is used to store the electrical energy. The charged PFN is then discharged into a klystron by firing a high voltage Thyratron switch. This discharge generates a high voltage rectangular pulse across the klystron electrodes. The amplitude and phase of Klystron's RF output is governed by the high voltage pulse amplitude. The undesired RF amplitude and phase stability issues arises at the klystron's output due to inter-pulse and during the pulse amplitude variations. To reduce inter-pulse voltage variations, the PFN is required to be charged at the same voltage after every discharge cycle. At present, the combination of widely used resonant charging and deQing method is used to regulate the pulse to pulse PFN voltage variations but the charging transformer's leakage inductance puts an upper bound on the regulation achievable by this method. Here we have developed few insights of the deQing process and devised a new compensation method to compensate this undesired effect of charging transformer's leakage inductance on the pulse to pulse PFN voltage stability. This compensation is accomplished by the controlled partial discharging of the split PFN capacitor using a low voltage MOSFET switch. Theoretically, very high values of pulse to pulse voltage stability may be achieved using this method. This method may be used in deQing based existing modulators or in new modulators, to increase the pulse to pulse voltage stability, without having a very tight bound on charging transformer's leakage inductance. Given a stable charging power supply, this method may be used to further enhance the inter-pulse voltage stability of modulators which employ the direct charging, after replacing the direct charging with the

  5. FGMOS Based Voltage-Controlled Grounded Resistor

    Directory of Open Access Journals (Sweden)

    R. Pandey

    2010-09-01

    Full Text Available This paper proposes a new floating gate MOSFET (FGMOS based voltage-controlled grounded resistor. In the proposed circuit FGMOS operating in the ohmic region is linearized by another conventional MOSFET operating in the saturation region. The major advantages of FGMOS based voltage-controlled grounded resistor (FGVCGR are simplicity, low total harmonic distortion (THD, and low power consumption. A simple application of this FGVCGR as a tunable high-pass filter is also suggested. The proposed circuits operate at the supply voltages of +/-0.75 V. The circuits are designed and simulated using SPICE in 0.25-µm CMOS technology. The simulation results of FGVCGR demonstrate a THD of 0.28% for the input signal 0.32 Vpp at 45 kHz, and a maximum power consumption of 254 µW.

  6. Optimal coordinated voltage control of power systems

    Institute of Scientific and Technical Information of China (English)

    LI Yan-jun; HILL David J.; WU Tie-jun

    2006-01-01

    An immune algorithm solution is proposed in this paper to deal with the problem of optimal coordination of local physically based controllers in order to preserve or retain mid and long term voltage stability. This problem is in fact a global coordination control problem which involves not only sequencing and timing different control devices but also tuning the parameters of controllers. A multi-stage coordinated control scheme is presented, aiming at retaining good voltage levels with minimal control efforts and costs after severe disturbances in power systems. A self-pattern-recognized vaccination procedure is developed to transfer effective heuristic information into the new generation of solution candidates to speed up the convergence of the search procedure to global optima. An example of four bus power system case study is investigated to show the effectiveness and efficiency of the proposed algorithm, compared with several existing approaches such as differential dynamic programming and tree-search.

  7. The VELO High Voltage System Control Software

    CERN Document Server

    Rakotomiaramanana, B; Eklund, L; De Capua, S

    2010-01-01

    This note describes the VELO high voltage control software. The implementation of its structure as a PVSS Finite State Machine is emphasized. The main error conditions that may occur during operation is also discussed. The VELO HV software conforms to the specification of the VELO.

  8. High voltage bus and auxiliary heater control system for an electric or hybrid vehicle

    Science.gov (United States)

    Murty, Balarama Vempaty

    2000-01-01

    A control system for an electric or hybrid electric vehicle includes a vehicle system controller and a control circuit having an electric immersion heater. The heater is electrically connected to the vehicle's high voltage bus and is thermally coupled to a coolant loop containing a heater core for the vehicle's climate control system. The system controller responds to cabin heat requests from the climate control system by generating a pulse width modulated signal that is used by the control circuit to operate the heater at a duty cycle appropriate for the amount of cabin heating requested. The control system also uses the heater to dissipate excess energy produced by an auxiliary power unit and to provide electric braking when regenerative braking is not desirable and manual braking is not necessary. The control system further utilizes the heater to provide a safe discharge of a bank of energy storage capacitors following disconnection of the battery or one of the high voltage connectors used to transmit high voltage operating power to the various vehicle systems. The control circuit includes a high voltage clamping circuit that monitors the voltage on the bus and operates the heater to clamp down the bus voltage when it exceeds a pre-selected maximum voltage. The control system can also be used to phase in operation of the heater when the bus voltage exceeds a lower threshold voltage and can be used to phase out the auxiliary power unit charging and regenerative braking when the battery becomes fully charged.

  9. Voltage-controlled nanoscale reconfigurable magnonic crystal

    Science.gov (United States)

    Wang, Qi; Chumak, Andrii V.; Jin, Lichuan; Zhang, Huaiwu; Hillebrands, Burkard; Zhong, Zhiyong

    2017-04-01

    A nanoscale reconfigurable magnonic crystal is designed using voltage-controlled perpendicular magnetic anisotropy (PMA) in ferromagnetic-dielectric heterostructures. A periodic array of gate metallic strips is placed on top of a MgO/Co structure in order to apply a periodic electric field and to modify the PMA in Co. It is numerically demonstrated that the introduction of PMA, which can be realized experimentally via applying a voltage, modifies the spin-wave propagation and leads to the formation of band gaps in the spin-wave spectrum. The band gaps can be controlled, i.e., it is possible to switch band gaps on and off within a few tens of nanoseconds. The width and the center frequency of the band gaps are defined by the applied voltage. Finally, it is shown that the introduction of PMA to selected, rather than to all gate strips allows for a predefined modification of the band-gap spectra. The proposed voltage-controlled reconfigurable magnonic crystal opens a way to low power consumption magnonic applications.

  10. How to Demonstrate the Voltage on a charged object in Physics Laboratory

    CERN Document Server

    Baddi, Raju

    2013-01-01

    Common Objects like a comb or a pen get charged when rubbed against something like human hair or garment clothing. Charged objects exhibit noticeable attractive or repulsive force lifting small pieces of paper or pushing/pulling a suspended light object charged with the same/opposite(uncharged) polarity respectively. This indicates the strong electrical nature of charged objects. Flashes due to spark between oppositely charged objects can be seen in total darkness. Implying a large potential difference between these charged objects which is not possible at lower voltages. This article describes a method to measure the voltage on commonly charged objects with respect to earth using simple instrumentation based on capacitors and CMOS voltmeter. Once the potential difference is known the average charge on the object can be calculated as well. The article also suggests a simple femto-farad capacitance meter for electrostatics work.

  11. Long Duration Balloon Charge Controller Stack Integration

    Science.gov (United States)

    Clifford, Kyle

    NASA and the Columbia Scientific Balloon Facility are interested in updating the design of the charge controller on their long duration balloon (LDB) in order to enable the charge controllers to be directly interfaced via RS232 serial communication by a ground testing computers and the balloon's flight computer without the need to have an external electronics stack. The design involves creating a board that will interface with the existing boards in the charge controller in order to receive telemetry from and send commands to those boards, and interface with a computer through serial communication. The inputs to the board are digital status inputs indicating things like whether the photovoltaic panels are connected or disconnected; and analog inputs with information such as the battery voltage and temperature. The outputs of the board are 100ms duration command pulses that will switch relays that do things like connect the photovoltaic panels. The main component of this design is a PIC microcontroller which translates the outputs of the existing charge controller into serial data when interrogated by a ground testing or flight computer. Other components involved in the design are an AD7888 12-bit analog to digital converter, a MAX3232 serial transceiver, various other ICs, capacitors, resistors, and connectors.

  12. High voltage source control on FODS

    Science.gov (United States)

    Patalakha, D. I.; Kalinin, A. Yu; Kulagin, N. V.

    2017-01-01

    The implementation of the high voltage power supply control system (HVPSCS) for experimental setup FODS (FOcusing Doublearmed Spectrometer) at accelerator U-70 of the Federal State Budgetary Institution State Research Center Of Russia Institute for High Energy Physics of the National Research Centre “Kurchatov Institute” (hereinafter referred to as IHEP) or for the test bench of the detector components is considered. The required set of hardware is defined and the appropriate software to operate HVPSCS is written in C/C++ codes. The date acquisition (DAQ) system [1] makes automatic control on HVPSCS for data taking run. It allows to get the dependence of appropriate detector parameters on the high voltage supply values and choose its optimal values for FODS detectors. The test run results of HVPSCS are presented.

  13. PIC BASED SOLAR CHARGING CONTROLLER FOR BATTERY

    Directory of Open Access Journals (Sweden)

    Mrs Jaya N. Ingole

    2012-02-01

    Full Text Available Solar resource is unlimited the government is trying to implement the use of Solar panels as an energy source in rural and sub urban areas for lighting the street lights, but the battery used to store the power gets affected due to overcharge & discharges. This paper presents the use of PIC16F72 based solar charger controller for controlling the overcharging and discharging of a solar cell. It works by continuously optimizing the interface between the solar array and battery. First, the variable supply is fixed at 12.8V dc—the voltage of a fully charged battery— and linked to the battery point of the circuit. Cut Off of battery from load voltage is 10.8 volt. A PIC16F72 for small size and inbuilt analog inputs is used to determine voltage level of battery and solar panel..It also describes how the disadvantages of analog circuit are overcome by this controller. The flow chart is also provided.

  14. A Synchrophasor Based Optimal Voltage Control Scheme with Successive Voltage Stability Margin Improvement

    Directory of Open Access Journals (Sweden)

    Heng-Yi Su

    2016-01-01

    Full Text Available This paper proposes an optimal control scheme based on a synchronized phasor (synchrophasor for power system secondary voltage control. The framework covers voltage stability monitoring and control. Specifically, a voltage stability margin estimation algorithm is developed and built in the newly designed adaptive secondary voltage control (ASVC method to achieve more reliable and efficient voltage regulation in power systems. This new approach is applied to improve voltage profile across the entire power grid by an optimized plan for VAR (reactive power sources allocation; therefore, voltage stability margin of a power system can be increased to reduce the risk of voltage collapse. An extensive simulation study on the IEEE 30-bus test system is carried out to demonstrate the feasibility and effectiveness of the proposed scheme.

  15. Anomalous Threshold Voltage Variability of Nitride Based Charge Storage Nonvolatile Memory Devices

    Directory of Open Access Journals (Sweden)

    Meng Chuan Lee

    2013-01-01

    Full Text Available Conventional technology scaling is implemented to meet the insatiable demand of high memory density and low cost per bit of charge storage nonvolatile memory (NVM devices. In this study, effect of technology scaling to anomalous threshold voltage ( variability is investigated thoroughly on postcycled and baked nitride based charge storage NVM devices. After long annealing bake of high temperature, cell’s variability of each subsequent bake increases within stable distribution and found exacerbate by technology scaling. Apparent activation energy of this anomalous variability was derived through Arrhenius plots. Apparent activation energy (Eaa of this anomalous variability is 0.67 eV at sub-40 nm devices which is a reduction of approximately 2 times from 110 nm devices. Technology scaling clearly aggravates this anomalous variability, and this poses reliability challenges to applications that demand strict control, for example, reference cells that govern fundamental program, erase, and verify operations of NVM devices. Based on critical evidence, this anomalous variability is attributed to lateral displacement of trapped charges in nitride storage layer. Reliability implications of this study are elucidated. Moreover, potential mitigation methods are proposed to complement technology scaling to prolong the front-runner role of nitride based charge storage NVM in semiconductor flash memory market.

  16. Using electric vehicle charging strategies to maximize PV-integration in the low voltage grid

    Energy Technology Data Exchange (ETDEWEB)

    Niesse, Astrid; Troeschel, Martin; Scherfke, Stefan; Schuette, Steffen [OFFIS, Oldenburg (Germany). R and D Div. Energy; Sonnenschein, Michael [Oldenburg Univ. (Germany). Dept. of Computing Science

    2011-07-01

    The role of electric vehicles (EV) in the low voltage grid has been discussed lately in many projects. An efficient energy management system for control of the charging processes while considering grid aspects is expected to raise high potential to build up Smart Grid functions. One focal point is to learn about the potential synergetic effects from EV and renewable energies regarding two main questions: (1) Is it possible to load EV batteries largely based on renewable sources - in particular PV - to guarantee positive carbon minimizing effects? (2) Can managed EV charging lead to an increased integration of fluctuating renewable energy resources in the grid? These questions can only be dealt with by keeping the status of the power infrastructure in perspective at any time -reliability of supply has to be ensured with high penetration of both EV and renewable energy resources. We used a simulative approach to follow up on these, studying the effects of charging processes for different shares of electric vehicles in the rural area of north-west Germany using characteristic grid types. Starting from these, we built up target scenarios that met our goals: Maximize PV integration, stabilize the grid and still guarantee the EV users' mobility. In this paper we present the results of scenarios with maximized PV integration and show the importance of managed charging processes to make best use of renewable feed-in for mobility purposes.

  17. Achievable peak electrode voltage reduction by neurostimulators using descending staircase currents to deliver charge.

    Science.gov (United States)

    Halpern, Mark

    2011-01-01

    This paper considers the achievable reduction in peak voltage across two driving terminals of an RC circuit when delivering charge using a stepped current waveform, comprising a chosen number of steps of equal duration, compared with using a constant current over the total duration. This work has application to the design of neurostimulators giving reduced peak electrode voltage when delivering a given electric charge over a given time duration. Exact solutions for the greatest possible peak voltage reduction using two and three steps are given. Furthermore, it is shown that the achievable peak voltage reduction, for any given number of steps is identical for simple series RC circuits and parallel RC circuits, for appropriate different values of RC. It is conjectured that the maximum peak voltage reduction cannot be improved using a more complicated RC circuit.

  18. On-chip high-voltage generator design design methodology for charge pumps

    CERN Document Server

    Tanzawa, Toru

    2016-01-01

    This book provides various design techniques for switched-capacitor on-chip high-voltage generators, including charge pump circuits, regulators, level shifters, references, and oscillators.  Readers will see these techniques applied to system design in order to address the challenge of how the on-chip high-voltage generator is designed for Flash memories, LCD drivers, and other semiconductor devices to optimize the entire circuit area and power efficiency with a low voltage supply, while minimizing the cost.  This new edition includes a variety of useful updates, including coverage of power efficiency and comprehensive optimization methodologies for DC-DC voltage multipliers, modeling of extremely low voltage Dickson charge pumps, and modeling and optimum design of AC-DC switched-capacitor multipliers for energy harvesting and power transfer for RFID.

  19. Comparison of Algorithms for Control of Loads for Voltage Regulation

    DEFF Research Database (Denmark)

    Douglass, Philip James; Han, Xue; You, Shi

    2014-01-01

    Autonomous flexible loads can be utilized to regulate voltag e on low voltage feeders. This paper compares two algorithms for controllin g loads: a simple voltage droop, where load power consumption is a varied in proportio n to RMS voltage; and a normalized relative voltage droop, which modifies...... the simpl e voltage droop by subtracting the mean voltage value at the bus and dividing by the standard deviation. These two controllers are applied to hot water heaters simul ated in a simple residential feeder. The simulation results show that both controllers r educe the frequency of undervoltage events...

  20. Voltage-controlled Enzymes: The new Janus Bifrons

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Villalba-Galea

    2012-09-01

    Full Text Available The Ciona intestinalis voltage sensitive phosphatase, Ci-VSP, was the first Voltage-controlled Enzyme (VEnz proven to be under direct command of the membrane potential. The discovery of Ci-VSP conjugated voltage sensitivity and enzymatic activity in a single protein. These two facets of Ci-VSP activity have provided a unique model for studying how membrane potential is sensed by proteins and a novel mechanism for control of enzymatic activity. These facets make Ci-VSP a fascinating and versatile enzyme.Ci-VSP has a voltage sensing domain (VSD that resembles those found in voltage-gated channels (VGC. The VSD resides in the N-terminus and is formed by four putative trans-membrane segments. The fourth segment contains charged residues which are likely involved in voltage sensing. Ci-VSP produces sensing currents in response to changes in potential, within a defined range of voltages. Sensing currents are analogous to gating currents in VGC. As known, these latter proteins contain four VSDs which are entangled in a complex interaction with the pore domain –the effector domain in VGC. This complexity makes studying the basis of voltage sensing in VGC a difficult enterprise. In contrast, Ci-VSP is thought to be monomeric and its catalytic domain –the VSP’s effector domain– can be cleaved off without disrupting the basic electrical functioning of the VSD. For these reasons, VSPs are considered a great model for studying the activity of a VSD in isolation. Finally, VSPs are also phosphoinositide phosphatases. Phosphoinositides are signaling lipids found in eukaryotes and are involved in many processes, including modulation of VGC activity and regulation of cell proliferation. Understanding VSPs as VEnz has been the center of attention in recent years and several reviews has been dedicated to this area. Thus, this review will be focused instead on the other face of this true Janus Bifrons and recapitulate what is known about VSPs as electrically

  1. Resonance analysis in parallel voltage-controlled Distributed Generation inverters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2013-01-01

    Thanks to the fast responses of the inner voltage and current control loops, the dynamic behaviors of parallel voltage-controlled Distributed Generation (DG) inverters not only relies on the stability of load sharing among them, but subjects to the interactions between the voltage control loops o...

  2. Secondary Voltage Control for Harmonics Suppression in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Guerrero, Josep M.; Blaabjerg, Frede

    2011-01-01

    This paper proposes a secondary voltage waveform control approach to suppress harmonics in islanded microgrids. Compared with the secondary control for traditional large power systems, the proposed control scheme can regulate the voltage waveform instead of voltage magnitude of sensitive buses in...

  3. MPPT algorithm for voltage controlled PV inverters

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco;

    2008-01-01

    This paper presents a novel concept for an MPPT that can be used in case of a voltage controlled grid connected PV inverters. In case of single-phase systems, the 100 Hz ripple in the AC power is also present on the DC side. Depending on the DC link capacitor, this power fluctuation can be used t...... to track the MPP of the PV array, using the information that at MPP the power oscillations are very small. In this way the algorithm can detect the fact that the current working point is at the MPP, for the current atmospheric conditions....

  4. New Control Technique Applied in Dynamic Voltage Restorer for Voltage Sag Mitigation

    Directory of Open Access Journals (Sweden)

    Rosli Omar

    2010-01-01

    Full Text Available The Dynamic Voltage Restorer (DVR was a power electronics device that was able to compensate voltage sags on critical loads dynamically. The DVR consists of VSC, injection transformers, passive filters and energy storage (lead acid battery. By injecting an appropriate voltage, the DVR restores a voltage waveform and ensures constant load voltage. There were so many types of the control techniques being used in DVR for mitigating voltage sags. The efficiency of the DVR depends on the efficiency of the control technique involved in switching the inverter. Problem statement: Simulation and experimental investigation toward new algorithms development based on SVPWM. Understanding the nature of DVR and performance comparisons between the various controller technologies available. The proposed controller using space vector modulation techniques obtain higher amplitude modulation indexes if compared with conventional SPWM techniques. Moreover, space vector modulation techniques can be easily implemented using digital processors. Space vector PWM can produce about 15% higher output voltage than standard Sinusoidal PWM. Approach: The purpose of this research was to study the implementation of SVPWM in DVR. The proposed control algorithm was investigated through computer simulation by using PSCAD/EMTDC software. Results: From simulation and experimental results showed the effectiveness and efficiency of the proposed controller based on SVPWM in mitigating voltage sags in low voltage distribution systems. It was concluded that its controller also works well both in balance and unbalance conditions of voltages. Conclusion/Recommendations: The simulation and experimental results of a DVR using PSCAD/EMTDC software based on SVPWM technique showed clearly the performance of the DVR in mitigating voltage sags. The DVR operates without any difficulties to inject the appropriate voltage component to correct rapidly any anomaly in the supply voltage to keep the

  5. On the use of an Arduino-based controller to control the charging process of a wind turbine

    Science.gov (United States)

    Mahmuddin, Faisal; Yusran, Ahmad Muhtam; Klara, Syerly

    2017-02-01

    In order to avoid an excessive charging voltage which can damage power storage when converting wind energy using a turbine, it is necessary to control the charging voltage of the turbine generator. In the present study, a charging controller which uses an Arduino microcontroller, is designed. 3 (three) indicator lights are installed to indicate the battery charging process, power diversion to dummy load and battery power level. The performance of the designed controller is evaluated by simulating 3 cases. In this simulation, a battery with maximum voltage of 12.4 V is used. Case 1 is performed with input voltage equals the one set in Arduino which is 10 V. In this case, the battery is charged up to 10.8 V. In case 2, the input voltage is 13 V while the maximum voltage set in Arduino is also 13 V. In this case, the battery is charged up to maximum voltage of the battery. Moreover, the dummy load indicator is ON and charging indicator is OFF after the maximum charging voltage is reached because the electricity is flowed to the dummy load. In the final case, the input voltage is set to be 16 V while the maximum voltage set in Arduino is 13 V. In this case, the charging indicator is OFF and dummy load indicator is ON which means that the Arduino has successfully switched the power to be flowed to dummy load. From the 3 (three) cases, it can be concluded that the designed controller works perfectly to control the charging process of the wind turbine. Moreover, the charging time needed in each case can also be determined.

  6. Testing, Performance and Reliability Evaluation of Charge Controllers for Solar Photovoltaic Home Lighting System in India

    Directory of Open Access Journals (Sweden)

    Adarsh Kumar

    2016-01-01

    Full Text Available :Charge controller is the most important part of a Solar Photovoltaic Home LightingSystem (SPVHLS which controls the charging ofbattery from photovoltaic (PV module and discharging of battery through load. This paper analyzes testresults of fourteen charge controllers (CC available in Indiaaccording to the Ministry of New and RenewableEnergy (MNRE specification. The different parameters of charge controllers to be tested arebattery high voltage disconnect (HVD, low voltage disconnect(LVD, load reconnect voltage (LRV, short circuit protection etc. It is found thatseven charge controllers meet the technical specifications ofMNRE. There is also a study of different features and properties of the chargecontrollers. Finally a brief discussion on selection appropriate charge controller for Solar Photovoltaic Home LightingSystem (SPVHLS and further improvement ofcharge controller is presented.

  7. Hierarchical Control Scheme for Voltage Unbalance Compensation in Islanded Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza;

    2011-01-01

    active and reactive power controllers, virtual impedance loop and voltage and current controllers. The secondary level is designed to compensate the voltage unbalance at the load bus (LB) of the islanded microgrid. Also, restoration of LB voltage amplitude and microgrid frequency to the rated values...... is considered in the secondary level. These functions are achieved by proper control of distributed generators (DGs) interface converters. The presented simulation results show the effectiveness of the proposed control structure in compensating the voltage unbalance and restoring the voltage amplitude...

  8. Write operation in MRAM with voltage controlled magnetic anisotropy

    Science.gov (United States)

    Munira, Kamaram; Pandey, Sumeet; Sandhu, Gurtej

    In non-volatile Magnetic RAM, information is saved in the bistable configuration of the free layer in a magnetic tunnel junction (MTJ). New information can be written to the free layer through magnetic induction (Toggle MRAM) or manipulation of magnetization using electric currents (Spin Transfer Torque MRAM or STT-MRAM). Both of the writing methods suffer from a shortcoming in terms of energy efficiency. This limitation on energy performance is brought about by the need for driving relatively large electrical charge currents through the devices for switching. In STT-MRAM, the nonzero voltage drop across the resistive MTJ leads to significant power dissipation. An energy efficient way to write may be with the assistance of voltage controlled magnetic anisotropy (VCMA), where voltage applied across the MTJ creates an electric field that modulates the interfacial anisotropy between the insulator and free layer. However, VCMA cannot switch the free layer completely by 180 degree rotation of magnetization. It can lower the barrier between the two stable configurations or at best, cancel the barrier, allowing 90 degree rotation. A second mechanism, spin torque or magnetic field, is needed to direct the final switching destination.

  9. Voltage and frequency control in the Islanded portion of the CIGRE Low Voltage distribution network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak, Claus Leth; Buriro, Ehsan Ali

    2017-01-01

    imbalance in the islanded MG. The voltage and the frequency of the islanded MG can be restored to the permissible limits if the desired/exceeded amount of active and reactive power is injected/absorbed by the locally available sources in islanded MG. This paper proposes the control strategy which can...... by providing some ancillary services. The main focus of this paper is about the development of a control system for the islanded MG, the selection of Voltage-Frequency controller for the most suitable DG unit of the Low Voltage test network and the control of voltage and frequency in islanding condition. Under...... compensate the problems of the voltage and the frequency deviations in the islanded MG. The selection of the VF controller for the most suitable DG unit of the LV test network is also presented in this paper and effectiveness of the controllers is verified by presenting simulation results...

  10. Design and Comparative Study of Three Photovoltaic Battery Charge Control Algorithms in MATLAB/SIMULINK Environment

    Directory of Open Access Journals (Sweden)

    Ankur Bhattacharjee

    2012-09-01

    Full Text Available This paper contains the design of a three stage solar battery charge controller and a comparative study of this charge control technique with three conventional solar battery charge control techniques such as 1. Constant Current (CC charging, 2. Two stage constant current constant voltage (CC-CV charging technique. The analysis and the comparative study of the aforesaid charging techniques are done in MATLAB/SIMULINK environment. Here the practical data used to simulate the charge control algorithms are based on a 12Volts 7Ah Sealed lead acid battery.

  11. Investigation of phase-wise voltage regulator control logics for compensating voltage deviations in an experimental low voltage network

    DEFF Research Database (Denmark)

    Hu, Junjie; Zecchino, Antonio; Marinelli, Mattia

    2016-01-01

    either locally or remotely. To evaluate and compare the control performances of the three control logics, all the tests use the same loading profiles. The experimental results indicate that the modified line compensation control can regulate voltage in a safe band in the case of various load......This paper investigates the control logics of an on-load tap-changer (OLTC) transformer by means of an experimental system validation. The experimental low-voltage unbalanced system consists of a decoupled single-phase OLTC transformer, a 75-metre 16 mm2 cable, a controllable single-phase resistive...... load and an electric vehicle, which has the vehicle-to-grid function. Three control logics of the OLTC transformer are described in the study. The three control logics are classified based on their control objectives and control inputs, which include network currents and voltages, and can be measured...

  12. P Voltage Control of DFIG with Two-Mass-Shaft Turbine Model Under Utility Voltage Disturbance

    Directory of Open Access Journals (Sweden)

    Hengameh Kojooyan Jafari

    2016-06-01

    Full Text Available Doubly fed induction generators as a variable speed induction generators are applied instead of other electric machines in wind power plants to be connected to the grid with flexible controllers. Nowadays one of the most important subjects in wind farms is control of output power delivered to the grid under utility disturbance. In this paper, a doubly-fed induction generator with external rotor resistance and power converters model as an external voltage source having an adjustable phase and amplitude with an ordinary turbine connected to one mass shaft model and also two mass shaft model, is used and controlled by a P voltage controller to control the output active power for typical high and low wind speeds under two conditions of utility disturbance; while time of disturbance is not too long to change the domain of external rotor voltage source and also while time is long and the domain of external rotor voltage decreases.Simulation results show that P voltage controller can control output active power under 27% stator voltage drop down for typical low wind speed and 11% stator voltage drop down for typical high wind speed in long time disturbance while 80% of rotor external voltage domain drops down under short time utility disturbance.

  13. Secondary control for voltage unbalance compensation in an islanded microgrid

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

    2011-01-01

    In this paper, the concept of secondary control is applied for voltage unbalance compensation in an islanded microgrid. The aim of the proposed control approach is to enhance the voltage quality at the point of common coupling (PCC). Unbalance compensation is achieved by proper control of distrib......In this paper, the concept of secondary control is applied for voltage unbalance compensation in an islanded microgrid. The aim of the proposed control approach is to enhance the voltage quality at the point of common coupling (PCC). Unbalance compensation is achieved by proper control...

  14. Study of Voltage-Controlled Characteristics for Thermoelectric Coolers

    Science.gov (United States)

    Wang, Ning; Chen, Ming-Ming; Jia, Hong-Zhi; Jin, Tao; Xie, Ji-Long

    2017-01-01

    Based on the Peltier effect, thermoelectric coolers (TECs) have been widely used in solving thermal management issues for semiconductor devices such as semiconductor laser, charge-coupled devices and nanoelectronic circuits with hot-spots. However, performance control mechanisms especially voltage-controlled parameters for TEC still face challenges. In this paper, a standard mathematical model for multi-stage TECs is proposed with thermal resistances from both sides and performance parameters dependent on voltage. The proposed models agreed with experimental results. Compared with the available model, the relative standard deviations between the obtained equivalent thermal conductivity model and experimental results at 25°C and 50°C are decreased by 88.87% and 30.14%, respectively. Also, the relative standard deviations between the proposed thermoelectric figure of merits model and calculated results based on experiments at two different temperatures are decreased by 84.45% and 62.94%, respectively. The results provide a controllable method of thermoelectric characteristics with high accuracy, which can be employed for early thermometric performance estimation for TEC design.

  15. Program-Controlled High Voltage Module in Active Voltage Dividers(AVD) for MPGD

    CERN Document Server

    Ginting, Muhammad Fadhil

    2016-01-01

    Micro Pattern Gas Detectors (MPGD) applications are rapidly developing and became an important part of upgrades for the LHC detectors. RD51/CERN have worked on Active Voltage Divider (AVD) technology for multistage MPGDs, One of the next developments for the AVD is to design and integrate high voltage module in a single box. The Program-Controlled High Voltage Module, part of one AIDA2020 project, has been successfully designed and developed, and can be integrated in AVD design.

  16. Programable Driver for Voltage-Controlled Oscillators

    Science.gov (United States)

    Fowler, L. E.; Mcneil, J. A.

    1985-01-01

    Electronically programable read-only memory (EPROM) and digital-to-analog converter provide customized time-varying voltage for frequency modulation. Voltage used to modulate IMPATT oscillator that serves as microwave pump for solid-state maser in low-noise amplifier. EPROM simple to tailor voltage waveform to suit characteristics of given maser. Digital information for waveform programed into EPROM chip; digital-to-analog converter reads information and produces corresponding analog wave. Principle readily adapted to other applications.

  17. Market-based coordinated charging of electric vehicles on the low-voltage distribution grid

    NARCIS (Netherlands)

    Ghijsen, M.; D'hulst, R

    2011-01-01

    This paper presents a market based coordination mechanism for charging electric vehicles. In market based coordination, a virtual market is used to match supply and demand of a commodity. The goal is to limit the impact of the electric vehicles on the low voltage distribution grid. First it is shown

  18. Bidirectional Flyback Converter with Multiple Series Connected Outputs for High Voltage Capacitive Charge and Discharge Applications

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe;

    2015-01-01

    This paper evaluates two different implementations of a bidirectional flyback converter for driving a capacitive electro active actuator, which must be charged and discharged from 0 V to 2.5 kV DC and vice versa, supplied from a 24 V battery. In one implementation, a high voltage MOSFET (4 kV) in...

  19. Charge-sharing SAR ADCs for low-voltage low-power applications

    CERN Document Server

    Rabuske, Taimur

    2017-01-01

    This book introduces readers to the potential of charge-sharing (CS) successive approximation register (SAR) analog-to-digital converters (ADCs), while providing extensive analysis of the factors that limit the performance of the CS topology. The authors present guidelines and useful techniques for mitigating the limitations of the architecture, while focusing on the implementation under restricted power budgets and voltage supplies.

  20. Market-based coordinated charging of electric vehicles on the low-voltage distribution grid

    NARCIS (Netherlands)

    Ghijsen, M.; D'hulst, R

    2011-01-01

    This paper presents a market based coordination mechanism for charging electric vehicles. In market based coordination, a virtual market is used to match supply and demand of a commodity. The goal is to limit the impact of the electric vehicles on the low voltage distribution grid. First it is shown

  1. Control Algorithms Charge Batteries Faster

    Science.gov (United States)

    2012-01-01

    On March 29, 2011, NASA s Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft beamed a milestone image to Earth: the first photo of Mercury taken from orbit around the solar system s innermost planet. (MESSENGER is also the first spacecraft to orbit Mercury.) Like most of NASA s deep space probes, MESSENGER is enabled by a complex power system that allows its science instruments and communications to function continuously as it travels millions of miles from Earth. "Typically, there isn't one particular power source that can support the entire mission," says Linda Taylor, electrical engineer in Glenn Research Center s Power Systems Analysis Branch. "If you have solar arrays and you are in orbit, at some point you re going to be in eclipse." Because of this, Taylor explains, spacecraft like MESSENGER feature hybrid power systems. MESSENGER is powered by a two-panel solar array coupled with a nickel hydrogen battery. The solar arrays provide energy to the probe and charge the battery; when the spacecraft s orbit carries it behind Mercury and out of the Sun s light, the spacecraft switches to battery power to continue operations. Typically, hybrid systems with multiple power inputs and a battery acting alternately as storage and a power source require multiple converters to handle the power flow between the devices, Taylor says. (Power converters change the qualities of electrical energy, such as from alternating current to direct current, or between different levels of voltage or frequency.) This contributes to a pair of major concerns for spacecraft design. "Weight and size are big drivers for any space application," Taylor says, noting that every pound added to a space vehicle incurs significant costs. For an innovative solution to managing power flows in a lightweight, cost-effective manner, NASA turned to a private industry partner.

  2. Charge collection and capacitance-voltage analysis in irradiated n-type magnetic Czochralski silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Petterson, M.K.; Sadrozinski, H.F.-W.; Betancourt, C. [SCIPP UC Santa Cruz, 1156 High Street, 95064 CA (United States); Bruzzi, M. [INFN, Dipartimento di Energetica, Universita di Firenze, via S. Marta 3, 50139 Florence (Italy)], E-mail: mara.bruzzi@unifi.it; Scaringella, M.; Tosi, C.; Macchiolo, A. [INFN, Dipartimento di Energetica, Universita di Firenze, via S. Marta 3, 50139 Florence (Italy); Manna, N.; Creanza, D. [Universita di Bari (Italy); Boscardin, M.; Piemonte, C.; Zorzi, N. [ITC, IRST, Povo, Trento (Italy); Borrello, L.; Messineo, A. [INFN Pisa (Italy); Dalla Betta, G.F. [Universita di Trento (Italy)

    2007-12-11

    The depletion depth of irradiated n-type silicon microstrip detectors can be inferred from both the reciprocal capacitance and from the amount of collected charge. Capacitance voltage (C-V) measurements at different frequencies and temperatures are being compared with the bias voltage dependence of the charge collection on an irradiated n-type magnetic Czochralski silicon detector. Good agreement between the reciprocal capacitance and the median collected charge is found when the frequency of the C-V measurement is selected such that it scales with the temperature dependence of the leakage current. Measuring C-V characteristics at prescribed combinations of temperature and frequency allows then a realistic estimate of the depletion characteristics of irradiated silicon strip detectors based on C-V data alone.

  3. Voltage control in active, intelligent low-voltage distribution networks; Spannungshaltung in aktiven, intelligenten Niederspannungsnetzen

    Energy Technology Data Exchange (ETDEWEB)

    Buelo, Thorsten; Mende, Denis [SMA Solar Technology AG, Niestetal (Germany); Geibel, Dominik [Fraunhofer Institut fuer Windenergie und Energiesystemtechnik (IWES), Kassel (Germany)] [and others

    2012-07-01

    This paper describes approaches for the voltage control in low-voltage distribution networks with a high share of distributed energy resources (DER). Taken into account are devices such as distribution transformers with on-load tap changer (OLTC), photovoltaic-inverters with reactive power capability and electronic voltage controllers (EVC). After a short description regarding voltage control, the devices and selected system concepts as well as the advantages and disadvantages of the different devices are described. Finally, the system-concepts are compared using the example of a real low voltage network, taking into account the possible increase of hosting capacity of the network, curtailing losses and the amount of reactive energy to be provided. (orig.)

  4. Variable Rail Voltage Control of a Brushless DC (BLDC) Motor

    Science.gov (United States)

    2013-01-01

    Variable Rail Voltage Control of a Brushless DC (BLDC) Motor by Yuan Chen, Joseph Conroy, and William Nothwang ARL-TR-6308 January 2013...TR-6308 January 2013 Variable Rail Voltage Control of a Brushless DC (BLDC) Motor Yuan Chen, Joseph Conroy, and William Nothwang Sensors...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Variable Rail Voltage Control of a Brushless DC (BLDC) Motor 5a. CONTRACT NUMBER 5b. GRANT

  5. The Control Unit of a Single Phase Voltage Regulator

    CERN Document Server

    Colak, Ilknur

    2010-01-01

    Supplying regulated voltage to critical loads is an important topic for several years. This paper presents a single-phase electronic voltage regulator based on high frequency switching of an isolated transformer where primary side voltage is controlled by two full-bridge converters sharing a common DC bus and operating at 50Hz and 20kHz switching frequencies. This allows 50Hz induced voltage on the primary side of the transformer, regulated by high frequency switching. Depending on the input voltage, voltage at the secondary side of the transformer add to (boost mode) or subtract (buck mode) from the supply voltage, therefore, maintaining a regulated voltage value across the load. The regulator is controlled by a digital controller allowing fast dynamic response. A 5kVA single-phase voltage regulator is realized to verify the operation of the proposed algorithm. The experimental results show that regulator maintains constant voltage across the load both in step-up (low supply voltage) and step-down (high supp...

  6. Analytical Charge Voltage Model in MOS Inversion Layer Based on Space Charge Capacitance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC,continuous expressions of surface potential and inversion layer carrier density are derived.Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.

  7. Voltage stability and controllability indices for multimachine power systems

    Energy Technology Data Exchange (ETDEWEB)

    Vournas, C.D. [National Technical Univ., Athens (Greece). Electrical Energy Systems Lab.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  8. Bidirectional Flyback Converter with Multiple Series Connected Outputs for High Voltage Capacitive Charge and Discharge Applications

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

    2015-01-01

    This paper evaluates two different implementations of a bidirectional flyback converter for driving a capacitive electro active actuator, which must be charged and discharged from 0 V to 2.5 kV DC and vice versa, supplied from a 24 V battery. In one implementation, a high voltage MOSFET (4 k...... by lower voltage rating MOSFETs driven by a gate drive transformer. Simulation results to compare the operation of conventional and proposed converters are provided. The advantages of proposed implementation are improved energy efficiency and lower cost. Experimental results with two series connected...

  9. Dynamic Performance of Grid Converters using Adaptive DC Voltage Control

    DEFF Research Database (Denmark)

    Trintis, Ionut; Sun, Bo; Guerrero, Josep M.;

    2014-01-01

    This paper investigates a controller that ensures minimum operating dc-link voltage of a back-to-back converter system. The dc-link voltage adapts its reference based on the system state, reference given by an outer loop to the dc-link voltage controller. The operating dc-link voltage should...... be kept as low as possible to increase the power conversion efficiency and increase the reliability of converters. The dynamic performance of the proposed controller is investigated by simulations and experiments....

  10. A control method for voltage balancing in modular multilevel converters

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2014-01-01

    The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages of its high modularity, availability, and high power quality. The voltage balancing of the floating capacitors in the cascaded submodules of the MMC is a key issue. In this paper......, a voltage-balancing control method is proposed. This method uses the phase-shifted carrier-based pulsewidth modulation scheme to control high-frequency current components for capacitor voltage balancing in the MMC without measuring the arm currents. Simulations and experimental studies of the MMC were...... conducted, and the results confirm the effectiveness of the proposed capacitor voltage-balancing control method....

  11. Automatic Voltage Control (AVC) System under Uncertainty from Wind Power

    DEFF Research Database (Denmark)

    Qin, Nan; Abildgaard, Hans; Flynn, Damian

    2016-01-01

    An automatic voltage control (AVC) system maintains the voltage profile of a power system in an acceptable range and minimizes the operational cost by coordinating the regulation of controllable components. Typically, all of the parameters in the optimization problem are assumed to be certain...... and constant in the decision making process. However, for high shares of wind power, uncertainty in the decision process due to wind power variability may result in an infeasible AVC solution. This paper proposes a voltage control approach which considers the voltage uncertainty from wind power productions....... The proposed method improves the performance and the robustness of a scenario based approach by estimating the potential voltage variations due to fluctuating wind power production, and introduces a voltage margin to protect the decision against uncertainty for each scenario. The effectiveness of the proposed...

  12. A Pulsed Power Supply with Sag Compensation using Controlled Gradational Voltage

    Science.gov (United States)

    Suzuki, Akihiro; Yamada, Masaki; Tashiro, Shojirou; Iwata, Akihiko

    A pulsed power supply with sag compensation using controlled gradational voltage to increase the flatness of output waveforms has been developed.The sag compensation circuit consists of compensation units connected in series. Each compensation unit consists of capacitances, diodes, and semiconductor switches. The capacitances of each unit are charged with different voltages by 2n (V0, 2V0, 4V0, ···). The compensation voltages, which has 2n-1 steps, is generated by switching the semiconductor switches of each unit in a binary sequence. Using this method, compensation voltage waveforms up to 6.2kV with 31 steps can be obtained with 5 compensation units. The sag compensation circuit has been adapted to a direct switch type pulsed power supply, which generates 7kV pulsed voltage with a pulse width of 700μs, thus realizing sag compensation.

  13. A simple method of extracting the polarization charge density in the AlGaN/GaN heterostructure from current-voltage and capacitance-voltage characteristics

    Institute of Scientific and Technical Information of China (English)

    Lü Yuan-Jie; Lin Zhao-Jun; Yu Ying-Xia; Meng Ling-Guo; Cao Zhi-Fang; Luan Chong-Biao; Wang Zhan-Guo

    2012-01-01

    An Ni Schottky contact on the AlGaN/GaN heterostructure is fabricated.The flat-band voltage for the Schottky contact on the AlGaN/GaN heterostructure is obtained from the forward current-voltage characteristics.With the measured capacitance-voltage curve and the flat-band voltage,the polarization charge density in the AlGaN/GaN heterostructure is investigated,and a simple formula for calculating the polarization charge density is obtained and analyzed.With the approach described in this paper,the obtained polarization charge density agrees well with the one calculated by self-consistently solving Schrodinger's and Poisson's equations.

  14. Robust Fallback Scheme for the Danish Automatic Voltage Control System

    DEFF Research Database (Denmark)

    Qin, Nan; Dmitrova, Evgenia; Lund, Torsten;

    2015-01-01

    This paper proposes a fallback scheme for the Danish automatic voltage control system. It will be activated in case of the local station loses telecommunication to the control center and/or the local station voltage violates the acceptable operational limits. It cuts in/out switchable and tap-abl...

  15. DFIG turbine representation for small signal voltage control studies

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez; Kjær, Philip Carne; Teodorescu, Remus

    2010-01-01

    This paper addresses the representation of a wind power plant, based on wound rotor asynchronous generators, with a centralized voltage controller, by an equivalent transfer function, valid for small signal voltage control studies. This representation allows to investigate the influence of the ce...

  16. A High-Voltage-Tolerant and Precise Charge-Balanced Neuro-Stimulator in Low Voltage CMOS Process.

    Science.gov (United States)

    Luo, Zhicong; Ker, Ming-Dou

    2016-12-01

    This paper presents a 4 × VDD neuro-stimulator in a 0.18- μm 1.8 V/3.3 V CMOS process. The self-adaption bias technique and stacked MOS configuration are used to prevent transistors from the electrical overstress and gate-oxide reliability issue. A high-voltage-tolerant level shifter with power-on protection is used to drive the neuro-stimulator The reliability measurement of up to 100 million periodic cycles with 3000- μA biphasic stimulations in 12-V power supply has verified that the proposed neuro-stimulator is robust. Precise charge balance is achieved by using a novel current memory cell with the dual calibration loops and leakage current compensation. The charge mismatch is down to 0.25% over all the stimulus current ranges (200-300 μA) The residual average dc current is less than 6.6 nA after shorting operation.

  17. Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems

    Science.gov (United States)

    Tuffner, Francis K [Richland, WA; Kintner-Meyer, Michael C. W. [Richland, WA; Hammerstrom, Donald J [West Richland, WA; Pratt, Richard M [Richland, WA

    2012-05-22

    Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems. According to one aspect, a battery charging control method includes accessing information regarding a presence of at least one of a surplus and a deficiency of electrical energy upon an electrical power distribution system at a plurality of different moments in time, and using the information, controlling an adjustment of an amount of the electrical energy provided from the electrical power distribution system to a rechargeable battery to charge the rechargeable battery.

  18. dc step response of induced-charge electro-osmosis between parallel electrodes at large voltages

    Science.gov (United States)

    Sugioka, Hideyuki

    2014-07-01

    Induced-charge electro-osmosis (ICEO) is important since it can be used for realizing high performance microfluidic devices. Here, we analyze the simplest problem of ion relaxation around a circular polarizable cylinder between parallel blocking electrodes in a closed cell by using a multiphysics coupled simulation technique. This technique is based on a combination of the finite-element method and finite-volume method for the Poisson-Nernst-Planck (PNP) equations having a flow term and the Stokes equation having an electric stress term. Through this analysis, we successfully demonstrate that on application of dc voltages, quadorapolar ICEO vortex flows grow during the charging time of the cylinder for both unbounded and bounded problems and decay during the charging time of the parallel electrodes only for the bounded problem using blocking electrodes. Further, by proposing a simple model that considers the two-dimensional (2D) PNP equations analytically, we successfully explain the step response time of the ICEO flow for the both unbounded and bounded problems. Furthermore, at low applied voltages, we find analytical formulations on steady diffused-ion problems and steady ICEO-flow problems and examine that our numerical results agree well with the analytical results. Moreover, by considering an ion-conserving condition with 2D Poisson-Boltzmann equations, we explain significant decrease of the maximum slip velocity at large applied voltages fairly well. We believe that our analysis will contribute greatly to the realistic designs of prospective high-performance microfluidic devices.

  19. Loss Minimization and Voltage Control in Smart Distribution Grid

    DEFF Research Database (Denmark)

    Juelsgaard, Morten; Sloth, Christoffer; Wisniewski, Rafal

    2014-01-01

    This work presents a strategy for increasing the installation of electric vehicles and solar panels in low-voltage grids, while obeying voltage variation constraints. Our approach employs minimization of active power losses for coordinating consumption and generation of power, as well as reactive...... power control to maintain satisfactory grid operation. Numerical case studies illustrate how our approach can significantly increase installation of both electric vehicles and solar panels, while avoiding unsatisfactory over- and under-voltages throughout the grid....

  20. Charged Residues at the First Transmembrane Region Contribute to the Voltage Dependence of the Slow Gate of Connexins.

    Science.gov (United States)

    Pinto, Bernardo I; García, Isaac E; Pupo, Amaury; Retamal, Mauricio A; Martínez, Agustín D; Latorre, Ramón; González, Carlos

    2016-07-22

    Connexins (Cxs) are a family of membrane-spanning proteins that form gap junction channels and hemichannels. Connexin-based channels exhibit two distinct voltage-dependent gating mechanisms termed slow and fast gating. Residues located at the C terminus of the first transmembrane segment (TM-1) are important structural components of the slow gate. Here, we determined the role of the charged residues at the end of TM-1 in voltage sensing in Cx26, Cx46, and Cx50. Conductance/voltage curves obtained from tail currents together with kinetics analysis reveal that the fast and slow gates of Cx26 involves the movement of two and four charges across the electric field, respectively. Primary sequence alignment of different Cxs shows the presence of well conserved glutamate residues in the C terminus of TM-1; only Cx26 contains a lysine in that position (lysine 41). Neutralization of lysine 41 in Cx26 increases the voltage dependence of the slow gate. Swapping of lysine 41 with glutamate 42 maintains the voltage dependence. In Cx46, neutralization of negative charges or addition of a positive charge in the Cx26 equivalent region reduced the slow gate voltage dependence. In Cx50, the addition of a glutamate in the same region decreased the voltage dependence, and the neutralization of a negative charge increased it. These results indicate that the charges at the end of TM-1 are part of the slow gate voltage sensor in Cxs. The fact that Cx42, which has no charge in this region, still presents voltage-dependent slow gating suggests that charges still unidentified also contribute to the slow gate voltage sensitivity.

  1. Design of a Novel Current Balanced Voltage Controlled Delay Element

    Directory of Open Access Journals (Sweden)

    Pooja Saxena

    2014-04-01

    Full Text Available This paper presents a design of fast voltage controlled delay element based on modified version of low noise Current Balanced Logic (CBL. This delay element provides identical rising and falling edge delays controlled by the single control voltage. The post layout tunable delay range is from 140 ps to 800 ps over control voltage range of 0 to 2.1 V. An analysis for the delay element is also presented, which is in agreement with the simulated delays. A Delay Lock Loop (DLL is designed using this delay element to verify its performance.

  2. Electric Vehicle IM Controller Based on Voltage-Fed Inverter

    Institute of Scientific and Technical Information of China (English)

    宋建国; 张承宁; 袁学; 谭建

    2004-01-01

    A novel electric vehicle (EV) induction motor (IM) controller based on voltage-fed inverter is presented. It is shown that the proposed adaptive control algorithm effectively both simplifies the structure and expands the capacity of controller. The relationship between stator's voltage and that of current under rotor's flux-oriented-coordinates is first introduced, and then the structure of vector control is analyzed, in which voltage compensation is inducted as the core feedback procedure. Experiments prove that, together with a facility for realization, a smooth transition, a prompt torque response and small concussion are gained. Extensive research conducted by varying parameters that result in practical ripple is proposed in conclusion.

  3. Development of a Microcontroller-based Battery Charge Controller for an Off-grid Photovoltaic System

    Science.gov (United States)

    Rina, Z. S.; Amin, N. A. M.; Hashim, M. S. M.; Majid, M. S. A.; Rojan, M. A.; Zaman, I.

    2017-08-01

    A development of a microcontroller-based charge controller for a 12V battery has been explained in this paper. The system is designed based on a novel algorithm to couple existing solar photovoltaic (PV) charging and main grid supply charging power source. One of the main purposes of the hybrid charge controller is to supply a continuous charging power source to the battery. Furthermore, the hybrid charge controller was developed to shorten the battery charging time taken. The algorithm is programmed in an Arduino Uno R3 microcontroller that monitors the battery voltage and generates appropriate commands for the charging power source selection. The solar energy is utilized whenever the solar irradiation is high. The main grid supply will be only consumed whenever the solar irradiation is low. This system ensures continuous charging power supply and faster charging of the battery.

  4. An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic System with Battery Energy Storage

    Directory of Open Access Journals (Sweden)

    Muhamad Zalani Daud

    2014-01-01

    Full Text Available This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV system with battery energy storage (BES. The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC. For the grid side VSC (G-VSC, two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.

  5. An optimal control strategy for DC bus voltage regulation in photovoltaic system with battery energy storage.

    Science.gov (United States)

    Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M A

    2014-01-01

    This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.

  6. Inductor Compensation in Three Phase PFC Control with Decoupling the Input Voltage and Bus Voltage

    Directory of Open Access Journals (Sweden)

    Luo Guang

    2016-01-01

    Full Text Available As the nonlinear structure of the boost ac/dc topology, the PFC is difficult to be controlled. The average state space theory has revealed that the choke current is determined by duty-ratio coupled with input voltage and bus voltage, which makes the high-performance sine-wave current track control more challenging. To remove disturbing variables and reduce the zero-crossing distortion, the decoupling control strategy is presented. Also, it is shown in this paper that the variable inductance has a great influence on PFC and THDI. As the inductor in boost converter varies with the current, a compensating coefficient of current is also proposed. The decoupling strategy and the inductor compensation strategy are implemented on a UPS with three phase input voltage. Numerical simulation and experimental results has indicated the high-performance of these control strategy.

  7. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    Science.gov (United States)

    Degtiarenko, Pavel V.; Popov, Vladimir E.

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  8. Stability Analysis and Controller Synthesis for Single-Loop Voltage-Controlled VSIs

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

    2017-01-01

    This paper analyzes the stability of the digital single-loop voltage-controlled Voltage-Source Inverters (VSIs) using linear voltage regulators. It reveals that the phase lags caused by using the resonant controller and the time delay of digital control system can stabilize the voltage loop without...... damping of the LC-filter resonance. The stability region for the digital single-loop resonant voltage control is then identified considering the effects of the discretization methods applied to the resonant controller. An enhanced voltage control scheme with widened stability region is subsequently...

  9. Model Predictive Control-Based Fast Charging for Vehicular Batteries

    Directory of Open Access Journals (Sweden)

    Zhibin Song

    2011-08-01

    Full Text Available Battery fast charging is one of the most significant and difficult techniques affecting the commercialization of electric vehicles (EVs. In this paper, we propose a fast charge framework based on model predictive control, with the aim of simultaneously reducing the charge duration, which represents the out-of-service time of vehicles, and the increase in temperature, which represents safety and energy efficiency during the charge process. The RC model is employed to predict the future State of Charge (SOC. A single mode lumped-parameter thermal model and a neural network trained by real experimental data are also applied to predict the future temperature in simulations and experiments respectively. A genetic algorithm is then applied to find the best charge sequence under a specified fitness function, which consists of two objectives: minimizing the charging duration and minimizing the increase in temperature. Both simulation and experiment demonstrate that the Pareto front of the proposed method dominates that of the most popular constant current constant voltage (CCCV charge method.

  10. Reproducible and controllable induction voltage adder for scaled beam experiments

    Science.gov (United States)

    Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko

    2016-08-01

    A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

  11. Control voltage and power fluctuations when connecting wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Berinde, Ioan, E-mail: ioan-berinde@yahoo.com; Bălan, Horia, E-mail: hbalan@mail.utcluj.ro; Oros, Teodora Susana, E-mail: teodoraoros-87@yahoo.com [Technical University of Cluj-Napoca, Romania, Faculty of Electrical Engineering, Department of Power Engineering and Management (Romania)

    2015-12-23

    Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

  12. Secondary Control for Voltage Quality Enhancement in Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

    2012-01-01

    In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each...... of these controllers includes a selective virtual impedance loop which is considered to improve sharing of fundamental and harmonic components of load current among the DG units. The sharing improvement is provided at the expense of increasing voltage unbalance and harmonic distortion. Thus, the secondary control...... level is applied to manage the compensation of SLB voltage unbalance and harmonics by sending proper control signals to the primary level. DGs compensation efforts are controlled locally at the primary level. The system design procedure for selecting proper control parameters is discussed. Simulation...

  13. Steric effects in the dynamics of electrolytes at large applied voltages: I. Double-layer charging

    CERN Document Server

    Kilic, M S; Ajdari, A; Kilic, Mustafa Sabri; Bazant, Martin Z.; Ajdari, Armand

    2006-01-01

    The classical Poisson-Boltzmann (PB) theory of electrolytes assumes a dilute solution of point charges with mean-field electrostatic forces. Even for very dilute solutions, however, it predicts absurdly large ion concentrations (exceeding close packing) for surface potentials of only a few tenths of a volt, which are often exceeded, e.g. in microfluidic pumps and electrochemical sensors. Since the 1950s, several modifications of the PB equation have been proposed to account for the finite size of ions in equilibrium, but in this two-part series, we consider steric effects on diffuse charge dynamics (in the absence of electro-osmotic flow). In this first part, we review the literature and analyze two simple models for the charging of a thin double layer, which must form a condensed layer of close-packed ions near the surface at high voltage. A surprising prediction is that the differential capacitance typically varies non-monotonically with the applied voltage, and thus so does the response time of an electrol...

  14. Charge Carrier Transport Mechanism Based on Stable Low Voltage Organic Bistable Memory Device.

    Science.gov (United States)

    Ramana, V V; Moodley, M K; Kumar, A B V Kiran; Kannan, V

    2015-05-01

    A solution processed two terminal organic bistable memory device was fabricated utilizing films of polymethyl methacrylate PMMA/ZnO/PMMA on top of ITO coated glass. Electrical characterization of the device structure showed that the two terminal device exhibited favorable switching characteristics with an ON/OFF ratio greater than 1 x 10(4) when the voltage was swept between - 2 V and +3 V. The device maintained its state after removal of the bias voltage. The device did not show degradation after a 1-h retention test at 120 degrees C. The memory functionality was consistent even after fifty cycles of operation. The charge transport switching mechanism is discussed on the basis of carrier transport mechanism and our analysis of the data shows that the charge carrier trans- port mechanism of the device during the writing process can be explained by thermionic emission (TE) and space-charge-limited-current (SCLC) mechanism models while erasing process could be explained by the FN tunneling mechanism. This demonstration provides a class of memory devices with the potential for low-cost, low-power consumption applications, such as a digital memory cell.

  15. Performance Characteristics of an Armature Voltage Controlled D.C. ...

    African Journals Online (AJOL)

    Performance Characteristics of an Armature Voltage Controlled D.C. Motor. ... the performance characteristics of a test motor are obtained by digital computer analysis. ... speed regulation and response characteristics for the d. c. drive system.

  16. Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz

    Science.gov (United States)

    Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

    2011-01-01

    A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

  17. Distributed Control of Battery Energy Storage Systems for Voltage Regulation in Distribution Networks with High PV Penetration

    DEFF Research Database (Denmark)

    Zeraati, Mehdi; Golshan, Mohamad Esmaeil Hamedani; Guerrero, Josep M.

    2017-01-01

    issues of distribution networks. In this paper, the battery energy storage (BES) systems are used in order to solve the voltage rise during the peak PV generation as well as the voltage drop while meeting the peak load. A coordinated control strategy is proposed to regulate the charge/discharge of BESs...... using a combination of the local droop based control method and a distributed control scheme which ensures the voltages of feeder remain within allowed limits. Therefore, two different consensus algorithms are used: The first algorithm determines the BESs participation in voltage regulation in terms......The voltage rise problem in low voltage (LV) distribution networks with high penetration of photovoltaic (PV) resources is one of the most important challenges in the development of these renewable resources since it may prevent the maximum PV penetration considering the reliability and security...

  18. Experimental study on high-voltage solar array sustained arc discharge induced by high charging

    Institute of Scientific and Technical Information of China (English)

    LI Kai; XIE ErQing; WANG Li; LIU YanXia; YANG Yang; SUN YanZheng; CUI XinYu; MAI ShengLi

    2007-01-01

    It has been reported that sustained arc discharge induced by electrostatic discharge (ESD) could cause permanent damage to high-power and high-voltage solar array of spacecrafts. The paper focuses on ESD simulating experiments on Si and GaAs samples, and induces sustained arc discharge. The physical mechanism of sustained arc discharge is discussed by comparing the charging/discharging phenomena between Si and GaAs samples. The experiments show that sustained arc discharge can produce a permanent short-circuit channel between solar cell strings through which the solar array's photovoltaic power may flow out sustainedly. The analyses show that sustained arc discharge strongly depends on solar array structure, solar array operating voltage, ESD characteristics and cell materials.

  19. Experimental study on high-voltage solar array sustained arc discharge induced by high charging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It has been reported that sustained arc discharge induced by electrostatic discharge (ESD) could cause permanent damage to high-power and high-voltage solar array of spacecrafts. The paper focuses on ESD simulating experiments on Si and GaAs samples, and induces sustained arc discharge. The physical mechanism of sustained arc discharge is discussed by comparing the charging/discharging phenomena between Si and GaAs samples. The experiments show that sustained arc discharge can produce a permanent short-circuit channel between solar cell strings through which the solar array’s photovoltaic power may flow out sustainedly. The analyses show that sustained arc discharge strongly depends on solar array structure, solar array operating voltage, ESD characteristics and cell materials.

  20. Optimal Coordinated Management of a Plug-In Electric Vehicle Charging Station under a Flexible Penalty Contract for Voltage Security

    Directory of Open Access Journals (Sweden)

    Jip Kim

    2016-07-01

    Full Text Available The increasing penetration of plug-in electric vehicles (PEVs may cause a low-voltage problem in the distribution network. In particular, the introduction of charging stations where multiple PEVs are simultaneously charged at the same bus can aggravate the low-voltage problem. Unlike a distribution network operator (DNO who has the overall responsibility for stable and reliable network operation, a charging station operator (CSO may schedule PEV charging without consideration for the resulting severe voltage drop. Therefore, there is a need for the DNO to impose a coordination measure to induce the CSO to adjust its charging schedule to help mitigate the voltage problem. Although the current time-of-use (TOU tariff is an indirect coordination measure that can motivate the CSO to shift its charging demand to off-peak time by imposing a high rate at the peak time, it is limited by its rigidity in that the network voltage condition cannot be flexibly reflected in the tariff. Therefore, a flexible penalty contract (FPC for voltage security to be used as a direct coordination measure is proposed. In addition, the optimal coordinated management is formulated. Using the Pacific Gas and Electric Company (PG&E 69-bus test distribution network, the effectiveness of the coordination was verified by comparison with the current TOU tariff.

  1. DESIGNING A PID CONTROLLER TO CONTROL A FUEL CELL VOLTAGE USING THE IMPERIALIST COMPETITIVE ALGORITHM

    Directory of Open Access Journals (Sweden)

    Mohammad Marefati

    2016-06-01

    Full Text Available In this article, an optimized PID controller for a fuel cell is introduced. It should be noted that we did not compute the PID controller’s coefficients based on trial-and-error method; instead, imperialist competitive algorithms have been considered. At first, the problem will be formulated as an optimization problem and solved by the mentioned algorithm, and optimized results will be obtained for PID coefficients. Then one of the important kinds of fuel cells, called proton exchange membrane fuel cell, is introduced. In order to control the voltage of this fuel cell during the changes in the charges, an optimal controller is introduced, based on the imperialist competitive algorithm. In order to apply this algorithm, the problem is written as an optimization problem which includes objectives and constraints. To achieve the most desirable controller, this algorithm is used for problem solving. Simulations confirm the better performance of proposed PID controller.

  2. Stability Boundaries for Offshore Wind Park Distributed Voltage Control

    DEFF Research Database (Denmark)

    Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz

    2017-01-01

    pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed...

  3. Current voltage characteristics of intrinsic Josephson junctions with charge-imbalance effect

    Science.gov (United States)

    Shukrinov, Yu. M.; Mahfouzi, F.

    2007-09-01

    The current-voltage characteristics (IVC) of intrinsic Josephson junctions are numerically calculated taking into account the quasiparticle charge-imbalance effect. We solve numerically the full set of the equations including second order differential equations for phase differences, kinetic equations and generalized Josephson relations for a stack of Josephson junctions. The boundary conditions due to the proximity effect are used. We obtain the branch structure of IVC and investigate it as a function of disequilibrium parameter at different values of coupling constant and McCumber parameter. An increase in the disequilibrium parameter essentially changes the character of IVC at large values of McCumber parameter.

  4. Current-voltage characteristics of intrinsic Josephson junctions with charge-imbalance effect

    Energy Technology Data Exchange (ETDEWEB)

    Shukrinov, Yu.M. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Physical Technical Institute, Dushanbe 734063 (Tajikistan)], E-mail: shukrinv@theor.jinr.ru; Mahfouzi, F. [Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Zanjan (Iran, Islamic Republic of)

    2007-09-01

    The current-voltage characteristics (IVC) of intrinsic Josephson junctions are numerically calculated taking into account the quasiparticle charge-imbalance effect. We solve numerically the full set of the equations including second order differential equations for phase differences, kinetic equations and generalized Josephson relations for a stack of Josephson junctions. The boundary conditions due to the proximity effect are used. We obtain the branch structure of IVC and investigate it as a function of disequilibrium parameter at different values of coupling constant and McCumber parameter. An increase in the disequilibrium parameter essentially changes the character of IVC at large values of McCumber parameter.

  5. Estimation of Transformer Parameters and Loss Analysis for High Voltage Capacitor Charging Application

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Ouyang, Ziwei

    2013-01-01

    In a bi-directional DC-DC converter for capacitive charging application, the losses associated with the transformer makes it a critical component. In order to calculate the transformer losses, its parameters such as AC resistance, leakage inductance and self capacitance of the high voltage (HV......) winding has to be estimated accurately. This paper analyzes the following losses of bi-directional flyback converter namely switching loss, conduction loss, gate drive loss, transformer core loss, and snubber loss, etc. Iterative analysis of transformer parameters viz., AC resistance, leakage inductance...

  6. Control Scheme for Distributed Generator Providing Network Voltage Support

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The distributed generator over the last 30 years has posed several challenges when they are connected to a distributed network. The most immediate problem is to change the voltage at the connection point depending on the power supplied to the network and may cause it to exceed statutory limits. This paper describes a new control scheme for a distributed generator for supporting the voltage control in the network, thus ensuring the distributed generator to contribute to network voltage management. The scheme performance is demonstrated by a model for a distributed generator connected to a distribution network. The result shows that using the new control scheme, the distribution network voltage constraints are maintained while maximizing the active power delivered by distributed generators.

  7. Stability Boundaries for Offshore Wind Park Distributed Voltage Control

    DEFF Research Database (Denmark)

    Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz;

    2016-01-01

    In order to identify mechanisms causing slow reactive power oscillations observed in an existing offshore wind power plant, and be able to avoid similar events in the future, voltage control is studied in this paper for a plant with a static synchronous compensator, type-4 wind turbines and a park...... pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed...... forward filter design are given to obtain required disturbance rejection properties. The paper contributes by providing analytical relations between power plant control, droop, sampling time, electrical parameters and voltage control characteristics, and by assessing frequencies and damping of reactive...

  8. A Microscopic Capacitor Model of Voltage Coupling in Membrane Proteins: Gating Charge Fluctuations in Ci-VSD.

    Science.gov (United States)

    Kim, Ilsoo; Warshel, Arieh

    2016-01-28

    The voltage sensitivity of membrane proteins is reflected in the response of the voltage sensing domains (VSDs) to the changes in membrane potential. This response is implicated in the displacement of positively charged residues, associated with the conformational changes of VSDs. The displaced charges generate nonlinear (i.e., voltage-dependent) capacitance current called the gating current (and its corresponding gating charge), which is a key experimental quantity that characterizes voltage activation in VSMP. However, the relevant theoretical/computational approaches, aimed to correlate the structural information on VSMP to electrophysiological measurements, have been rather limited, posing a broad challenge in computer simulations of VSMP. Concomitant with the development of our coarse-graining (CG) model of voltage coupling, we apply our theoretical framework for the treatments of voltage effects in membrane proteins to modeling the VSMP activation, taking the VSDs (Ci-VSD) derived from the Ciona intestinalis voltage sensitive phosphatase (Ci-VSP) as a model system. Our CG model reproduces the observed gating charge of Ci-VSD activation in several different perspectives. In particular, a new closed-form expression of the gating charge is evaluated in both nonequilibrium and equilibrium ways, while considering the fluctuation-dissipation relation that connects a nonequilibrium measurement of the gating charge to an equilibrium measurement of charge fluctuations (i.e., the voltage-independent linear component of membrane capacitance). In turn, the expression uncovers a novel link that connects an equilibrium measurement of the voltage-independent linear capacitance to a nonequilibrium measurement of the voltage-dependent nonlinear capacitance (whose integral over voltage is equal to the gating charge). In addition, our CG model yields capacitor-like voltage dependent free energy parabolas, resulting in the free energy difference and the free energy barrier for

  9. Novel Approach to Evaluation of Charging on Semiconductor Surface by Noncontact, Electrode-Free Capacitance/Voltage Measurement

    Science.gov (United States)

    Hirae, Sadao; Kohno, Motohiro; Okada, Hiroshi; Matsubara, Hideaki; Nakatani, Ikuyoshi; Kusuda, Tatsufumi; Sakai, Takamasa

    1994-04-01

    This paper describes a novel approach to the quantitative characterization of semiconductor surface charging caused by plasma exposures and ion implantations. The problems in conventional evaluation of charging are also discussed. Following the discussions above, the necessity of unified criteria is suggested for efficient development of systems or processes without charging damage. Hence, the charging saturation voltage between a top oxide surface and substrate, V s, and the charging density per unit area per second, ρ0, should be taken as criteria of charging behavior, which effectively represent the charging characteristics of both processes. The unified criteria can be obtained from the exposure time dependence of a net charging density on the thick field oxide. In order to determine V s and ρ0, the analysis using the C-V curve measured in a noncontact method with the metal-air-insulator-semiconductor (MAIS) technique is employed. The total space-charge density in oxide and its centroid can be determined at the same time by analyzing the flat-band voltage (V fb) of the MAIS capacitor as a function of the air gap. The net charge density can be obtained by analyzing the difference between the total space-charge density in oxide before and after charging. Finally, it is shown that charge damage of the large area metal-oxide-semiconductor (MOS) capacitor can be estimated from both V s and ρ0 which are obtained from results for a thick field oxide implanted with As+ and exposed to oxygen plasma.

  10. Experimental research on charging characteristics of a solar photovoltaic system by the pressure-control method

    Institute of Scientific and Technical Information of China (English)

    Hua ZHU; Zhang-lu XU; Zi-juan CAO

    2011-01-01

    The charging characteristics of the valve-regulated lead acid (VRLA) battery driven by solar energy were experimentally studied through the pressure-control method in this paper. The aims of the research were to increase charging efficiency to make the most of solar energy and to improve charging quality to prolong life of battery. The charging process of a 12 V 12 A.h VRLA battery has been tested under the mode of a stand-alone photovoltaic (PV) system. Results show that the pressure-control method can effectively control PV charging of the VRLA battery and make the best of PV cells through the maximum power point tracking (MPPT). The damage of VRLA battery by excess oxygen accumulation can be avoided through the inner pressure control of VRLA battery. Parameters such as solar radiation intensity, charging power, inner pressure of the battery, and charging current and voltage during the charging process were measured and analyzed.

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

    DEFF Research Database (Denmark)

    Luna, Alvaro; Lina, Kleber; Corcoles, Felipe

    2009-01-01

    under balanced conditions its behaviour is not good enough when the voltage of the mains is unbalanced, unless an independent control for the positive and the negative sequence is implemented. This paper proposes a new control system able to control the DFIG-WT under unbalanced conditions using a simple...

  12. Alternating current-generated plasma discharges for the controlled direct current charging of ferroelectrets

    Science.gov (United States)

    Cury Basso, Heitor; Monteiro, José Roberto B. de A.; Baladelli Mazulquim, Daniel; Teixeira de Paula, Geyverson; Gonçalves Neto, Luiz; Gerhard, Reimund

    2013-09-01

    The standard charging process for polymer ferroelectrets, e.g., from polypropylene foams or layered film systems involves the application of high DC fields either to metal electrodes or via a corona discharge. In this often-used process, the DC field triggers the internal breakdown and limits the final charge densities inside the ferroelectret cavities and, thus, the final polarization. Here, an AC + DC charging procedure is proposed and demonstrated in which a high-voltage high-frequency (HV-HF) wave train is applied together with a DC poling voltage. Thus, the internal dielectric-barrier discharges in the ferroelectret cavities are induced by the HV-HF wave train, while the final charge and polarization level is controlled separately through the applied DC voltage. In the new process, the frequency and the amplitude of the HV-HF wave train must be kept within critical boundaries that are closely related to the characteristics of the respective ferroelectrets. The charging method has been tested and investigated on a fluoropolymer-film system with a single well-defined cylindrical cavity. It is found that the internal electrical polarization of the cavity can be easily controlled and increases linearly with the applied DC voltage up to the breakdown voltage of the cavity. In the standard charging method, however, the DC voltage would have to be chosen above the respective breakdown voltage. With the new method, control of the HV-HF wave-train duration prevents a plasma-induced deterioration of the polymer surfaces inside the cavities. It is observed that the frequency of the HV-HF wave train during ferroelectret charging and the temperature applied during poling of ferroelectrics serve an analogous purpose. The analogy and the similarities between the proposed ferroelectret charging method and the poling of ferroelectric materials or dipole electrets at elevated temperatures with subsequent cooling under field are discussed.

  13. Stability of DC Voltage Droop Controllers in VSC HVDC Systems

    DEFF Research Database (Denmark)

    Thams, Florian; Suul, Jon Are; D’Arco, Salvatore;

    2015-01-01

    Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC-based conver......Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC...

  14. Buck supplies output voltage ripple reduction using fuzzy control

    Directory of Open Access Journals (Sweden)

    Nicu BIZON

    2007-12-01

    Full Text Available Using the PWM control for switching power supplies the peaks EMI noise appear at the switching frequency and its harmonics. Using randomize or chaotic PWM control techniques in these systems the power spectrum is spread out in all frequencies band spectral emissions, but with a bigger ripple in the output voltage. The proposed nonlinear feedback control method, which induces chaos, is based by fuzzy rules that minimize the output voltage ripple. The feasibility and effectiveness of this relative simple method is shown by simulation. A comparison with the previous control method is included, too.

  15. Control Strategy for Microgrid Inverter under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Liu, Wenzhao; Zhang, X.

    2014-01-01

    This paper presents the theoretical analysis of the inherent reason of current harmonic and power oscillation phenomena in case of operating the microgrid inverter under unbalanced grid voltage conditions. In order to flexibly control the current harmonic and power oscillation, a new stationary...... frame control strategy is proposed. It has a simple control structure due to no need of a phase-locked loop and voltage/current positive/negative sequence extraction calculation. The coordinate control of power and current quality is achieved, which enhances the operation performance of microgrid...

  16. The Space Charge Effect on the Discharge Current in Cross-Linked Polyethylene under High AC Voltages

    Science.gov (United States)

    Kwon, Yoon-Hyeok; Hwangbo, Seung; Lee, June-Ho; Yi, Dong-Young; Han, Min-Koo

    2003-12-01

    The space charge distributions in solid dielectrics have been usually investigated by means of the pulsed electroacoustic (PEA) method. However, most previous studies have been limited to the phenomenological analysis under DC voltages. In our study, the space charge distribution in cross-linked polyethylene (XLPE) has been measured using AC voltages by means of the modified PEA method. Simultaneously, the streamer discharges in an air gap have been measured in order to investigate the relationship between space charge and discharge current, and the relationship has been adapted to the case of dielectric barrier discharge. At high AC voltages, discharge current increases to the critical point, but no further increase is exhibited over the critical voltage and the discharge pattern is resolved by the space charge. This result indicates that the frequency effect and space charge characteristics of dielectric materials are preferred to the voltage effect in the adaptation to dielectric barrier discharge. The results well explain the space charge effect on partial discharge and the dielectric barrier discharge phenomenon.

  17. Persistent Hall voltages across thin planar charged quantum rings on the surface of a topological insulator

    Science.gov (United States)

    Durganandini, P.

    2015-03-01

    We consider thin planar charged quantum rings on the surface of a three dimensional topological insulator coated with a thin ferromagnetic layer. We show theoretically, that when the ring is threaded by a magnetic field, then, due to the Aharanov-Bohm effect, there are not only the well known circulating persistent currents in the ring but also oscillating persistent Hall voltages across the thin ring. Such oscillating persistent Hall voltages arise due to the topological magneto-electric effect associated with the axion electrodynamics exhibited by the surface electronic states of the three dimensional topological insulator when time reversal symmetry is broken. We further generalize to the case of dipole currents and show that analogous Hall dipole voltages arise. We also discuss the robustness of the effect and suggest possible experimental realizations in quantum rings made of semiconductor heterostructures. Such experiments could also provide new ways of observing the predicted topological magneto-electric effect in three dimensional topological insulators with time reversal symmetry breaking. I thank BCUD, Pune University, Pune for financial support through research grant.

  18. Stability Analysis and Controller Synthesis for Digital Single-Loop Voltage-Controlled Inverters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

    2016-01-01

    This paper analyzes first the stability of single-loop digital voltage control scheme for the LC-filtered voltage source inverters. It turns out that the phase lag, caused by the time delay of digital control system and by the use of integral controller, can stabilize the voltage loop without...... damping of LC-filter resonance. The stability regions are then identified with alternative voltage controller synthesized. For further widening the stability region, an active damping approach is proposed and co-designed with the voltage controller in the discrete z-domain. Simulations and experimental...

  19. Controlled Compact High Voltage Power Lines

    Directory of Open Access Journals (Sweden)

    Postolati V.

    2016-04-01

    Full Text Available Nowadays modern overhead transmission lines (OHL constructions having several significant differences from conventional ones are being used in power grids more and more widely. Implementation of compact overhead lines equipped with FACTS devices, including phase angle regulator settings (compact controlled OHL, appears to be one of the most effective ways of power grid development. Compact controlled AC HV OHL represent a new generation of power transmission lines embodying recent advanced achievements in design solutions, including towers and insulation, together with interconnection schemes and control systems. Results of comprehensive research and development in relation to 110–500kV compact controlled power transmission lines together with theoretical basis, substantiation, and methodological approaches to their practical application are presented in the present paper.

  20. Contribution of variable-speed wind turbines to voltage control

    Energy Technology Data Exchange (ETDEWEB)

    Ledesma, P.; Usaola, J.

    2003-07-01

    Variable speed, grid connected, wind turbines open new possibilities for voltage control, because they use electronic converters, which may regulate the reactive power interchange with the grid. This paper proposes two voltage control schemes for variable speed wind turbines with double-fed induction generator. The first scheme acts on the wind-turbine power factor, while the latter acts directly on the converter current. Advantages and draw backs of both techniques are discussed. Both control techniques have been tested by simulations of a base case, which represent a synchronous generator, a wind farm and a local load, and several disturbances such as the loss of compensator capacitors. (author)

  1. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification...... is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level...... control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis....

  2. Charging dynamics of a floating gate transistor with site-controlled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Maier, P., E-mail: patrick.maier@physik.uni-wuerzburg.de; Hartmann, F.; Emmerling, M.; Schneider, C.; Höfling, S.; Kamp, M.; Worschech, L. [Technische Physik, Physikalisches Institut, Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany)

    2014-08-04

    A quantum dot memory based on a GaAs/AlGaAs quantum wire with site-controlled InAs quantum dots was realized by means of molecular beam epitaxy and etching techniques. By sampling of different gate voltage sweeps for the determination of charging and discharging thresholds, it was found that discharging takes place at short time scales of μs, whereas several seconds of waiting times within a distinct negative gate voltage range were needed to charge the quantum dots. Such quantum dot structures have thus the potential to implement logic functions comprising charge and time dependent ingredients such as counting of signals or learning rules.

  3. Simple DCM or CRM analog peak current controller for HV capacitor charge-discharge applications

    DEFF Research Database (Denmark)

    Trintis, Ionut; Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a simple analog current controller suitable for buck and boost converter topologies. The controller operates in DCM or CRM, depending on the setup. The experimental results are presented to validate the proposed controller functionality for a high voltage capacitor charge...

  4. Space Charge Behavior in Paper Insulation Induced by Copper Sulfide in High-Voltage Direct Current Power Transformers

    Directory of Open Access Journals (Sweden)

    Ruijin Liao

    2015-08-01

    Full Text Available The main insulation system in high-voltage direct current (HVDC transformer consists of oil-paper insulation. The formation of space charge in insulation paper is crucial for the dielectric strength. Unfortunately, space charge behavior changes because of the corrosive sulfur substance in oil. This paper presents the space charge behavior in insulation paper induced by copper sulfide generated by corrosive sulfur in insulation oil. Thermal aging tests of paper-wrapped copper strip called the pigtail model were conducted at 130 °C in laboratory. Scanning electron microscopy (SEM was used to observe the surface of copper and paper. Pulse electroacoustic (PEA and thermally stimulated current (TSC methods were used to obtain the space charge behavior in paper. Results showed that both maximum and total amount of space charge increased for the insulation paper contaminated by semi-conductor chemical substance copper sulfide. The space charge decay rate of contaminated paper was significantly enhanced after the polarization voltage was removed. The TSC results revealed that copper sulfide increased the trap density and lowered the shallow trap energy levels. These results contributed to charge transportation by de-trapping and trapping processes. This improved charge transportation could be the main reason for the decreased breakdown voltage of paper insulation material.

  5. Voltage control of magnetism in multiferroic heterostructures

    OpenAIRE

    LIU, MING; Sun, Nian X.

    2014-01-01

    Electrical tuning of magnetism is of great fundamental and technical importance for fast, compact and ultra-low power electronic devices. Multiferroics, simultaneously exhibiting ferroelectricity and ferromagnetism, have attracted much interest owing to the capability of controlling magnetism by an electric field through magnetoelectric (ME) coupling. In particular, strong strain-mediated ME interaction observed in layered multiferroic heterostructures makes it practically possible for realiz...

  6. DFIG Harmonic Current Controlling with the Grid Low Harmonic Voltage

    Directory of Open Access Journals (Sweden)

    Huan Wang

    2014-01-01

    Full Text Available This study presents a vector control strategy based on stator harmonic current closed-loop, it adds individually the control loop about of each stator harmonic current to restrain the stator harmonic current, in order to meet the THD criteria. The control strategy of restraining the harmonic current presents the design of the stator harmonic current restrains the current controller. It influences the rotor voltage of the stator harmonic current restraining strategies.

  7. Design and Control of a Dynamic Voltage Restorer

    DEFF Research Database (Denmark)

    Nielsen, John Godsk

    . The advantages and disadvantages are treated by inserting the DVR in either the medium voltage distribution system or in the low voltage distribution system. Different topologies for a DVR are investigated on a converter and system level and the protection issues are treated. The design of a DVR is treated...... and two prototype DVRs are designed and specified. The first DVR is a low voltage DVR (LV-DVR) rated for 10 kVA for insertion in a 400 V low voltage grid and the second DVR is a high voltage DVR (HV-DVR) rated for 200 kVA for insertion in a 10 kV medium voltage distribution system. The control issues...... in order to aid the design process and perform simulations on a DVR. The simulations have been compared with measurements in order to be able to test the validity of the models. A good agreement have been found between simulations and measurements, which indicates that the system is sufficiently modelled...

  8. Controlling charge quantization with quantum fluctuations

    Science.gov (United States)

    Jezouin, S.; Iftikhar, Z.; Anthore, A.; Parmentier, F. D.; Gennser, U.; Cavanna, A.; Ouerghi, A.; Levkivskyi, I. P.; Idrisov, E.; Sukhorukov, E. V.; Glazman, L. I.; Pierre, F.

    2016-08-01

    In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.

  9. Control of ion energy and angular distributions using voltage waveform

    Energy Technology Data Exchange (ETDEWEB)

    Rauf, S.

    1999-07-01

    A number of plasma-aided microelectronics manufacturing processes sensitively depend on the ion characteristics at the substrate, in particular the ion energy (IEDF) and angular (IADF) distribution functions. The outcome of these processes can be much more precisely controlled if one has direct control over the IEDFs and IADFs. Past studies have explored the influence of rb bias voltage amplitude and frequency, inductive power deposition and gas pressure on the ion characteristics at the substrate. The factor that influences the ion dynamics most is however the time-dependent sheath voltage and, as demonstrated in this paper, sheath voltage can be accurately controlled using the rf bias voltage waveform. In this paper, the authors computationally examine the influence of the rf bias voltage waveform on the IEDFs and IADFs at the substrate in an inductively coupled plasma (ICP) reactor. This study has been conducted using a coupled set of the Hybrid Plasma Equipment Model (HPEM) and a circuit model, and the Plasma Chemistry Monte Carlo Simulation (PCMCS).

  10. A Voltage Controlled Oscillator using Ring Structure in CMOS Technology

    Directory of Open Access Journals (Sweden)

    Mrs. Devendra Rani

    2012-06-01

    Full Text Available Voltage-Controlled Ring Oscillators are crucial components in many wireless communication systems. The goal of this project is to design a high speed and lower power consumption, a voltage controlled oscillator (VCO, based on ring oscillators in 250nm CMOS technology, which provides a frequency of 2.4GHz. This CMOS based VCO is used for high speed wireless communication applications. A design of VCO includes delay cell, bias circuitry, and tuning circuitry using Tanner 13.0v software.

  11. Control and Protection Cooperation Strategy for Voltage Instability

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Sun, Haishun;

    2012-01-01

    Most cascaded blackouts are caused by unexpected backup relay operations due to low voltage or overload state caused by post fault load restoration dynamics. If such state can be sensed and adjusted appropriately prior to those relay actions, system stability might be sustained. This paper proposed...... a control and protection cooperation strategy to prevent post fault voltage instability. The multi-agent technology is applied for the strategy implementation; the criteria based on wide area measured apparent impedances are defined to choose the control strategy, such as tap changer adjusting or load...

  12. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan;

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  13. Voltage control of magnetism in multiferroic heterostructures.

    Science.gov (United States)

    Liu, Ming; Sun, Nian X

    2014-02-28

    Electrical tuning of magnetism is of great fundamental and technical importance for fast, compact and ultra-low power electronic devices. Multiferroics, simultaneously exhibiting ferroelectricity and ferromagnetism, have attracted much interest owing to the capability of controlling magnetism by an electric field through magnetoelectric (ME) coupling. In particular, strong strain-mediated ME interaction observed in layered multiferroic heterostructures makes it practically possible for realizing electrically reconfigurable microwave devices, ultra-low power electronics and magnetoelectric random access memories (MERAMs). In this review, we demonstrate this remarkable E-field manipulation of magnetism in various multiferroic composite systems, aiming at the creation of novel compact, lightweight, energy-efficient and tunable electronic and microwave devices. First of all, tunable microwave devices are demonstrated based on ferrite/ferroelectric and magnetic-metal/ferroelectric composites, showing giant ferromagnetic resonance (FMR) tunability with narrow FMR linewidth. Then, E-field manipulation of magnetoresistance in multiferroic anisotropic magnetoresistance and giant magnetoresistance devices for achieving low-power electronic devices is discussed. Finally, E-field control of exchange-bias and deterministic magnetization switching is demonstrated in exchange-coupled antiferromagnetic/ferromagnetic/ferroelectric multiferroic hetero-structures at room temperature, indicating an important step towards MERAMs. In addition, recent progress in electrically non-volatile tuning of magnetic states is also presented. These tunable multiferroic heterostructures and devices provide great opportunities for next-generation reconfigurable radio frequency/microwave communication systems and radars, spintronics, sensors and memories.

  14. Voltage control of magnetism in multiferroic heterostructures

    Science.gov (United States)

    Liu, Ming; Sun, Nian X.

    2014-01-01

    Electrical tuning of magnetism is of great fundamental and technical importance for fast, compact and ultra-low power electronic devices. Multiferroics, simultaneously exhibiting ferroelectricity and ferromagnetism, have attracted much interest owing to the capability of controlling magnetism by an electric field through magnetoelectric (ME) coupling. In particular, strong strain-mediated ME interaction observed in layered multiferroic heterostructures makes it practically possible for realizing electrically reconfigurable microwave devices, ultra-low power electronics and magnetoelectric random access memories (MERAMs). In this review, we demonstrate this remarkable E-field manipulation of magnetism in various multiferroic composite systems, aiming at the creation of novel compact, lightweight, energy-efficient and tunable electronic and microwave devices. First of all, tunable microwave devices are demonstrated based on ferrite/ferroelectric and magnetic-metal/ferroelectric composites, showing giant ferromagnetic resonance (FMR) tunability with narrow FMR linewidth. Then, E-field manipulation of magnetoresistance in multiferroic anisotropic magnetoresistance and giant magnetoresistance devices for achieving low-power electronic devices is discussed. Finally, E-field control of exchange-bias and deterministic magnetization switching is demonstrated in exchange-coupled antiferromagnetic/ferromagnetic/ferroelectric multiferroic hetero-structures at room temperature, indicating an important step towards MERAMs. In addition, recent progress in electrically non-volatile tuning of magnetic states is also presented. These tunable multiferroic heterostructures and devices provide great opportunities for next-generation reconfigurable radio frequency/microwave communication systems and radars, spintronics, sensors and memories. PMID:24421373

  15. Correlation between the Open-Circuit Voltage and Charge Transfer State Energy in Organic Photovoltaic Cells.

    Science.gov (United States)

    Zou, Yunlong; Holmes, Russell J

    2015-08-26

    In order to further improve the performance of organic photovoltaic cells (OPVs), it is essential to better understand the factors that limit the open-circuit voltage (VOC). Previous work has sought to correlate the value of VOC in donor-acceptor (D-A) OPVs to the interface energy level offset (EDA). In this work, measurements of electroluminescence are used to extract the charge transfer (CT) state energy for multiple small molecule D-A pairings. The CT state as measured from electroluminescence is found to show better correlation to the maximum VOC than EDA. The difference between EDA and the CT state energy is attributed to the Coulombic binding energy of the CT state. This correlation is demonstrated explicitly by inserting an insulating spacer layer between the donor and acceptor materials, reducing the binding energy of the CT state and increasing the measured VOC. These results demonstrate a direct correlation between maximum VOC and CT state energy.

  16. MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

    Institute of Scientific and Technical Information of China (English)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  17. Design and control of single-phase dynamic voltage restorer

    Indian Academy of Sciences (India)

    AMIT MEENA; SHIRAZUL ISLAM; SANDEEP ANAND; YOGESH SONAWANE; SANJAY TUNGARE

    2017-08-01

    Dynamic voltage restorer (DVR) is a custom power device used in electrical distribution system for power quality improvement. It ensures regulated voltage supply to the sensitive loads, even in case of voltage sag and swell disturbances in the distribution network. It is a series connected device and compensates voltagesag and swell by injecting a voltage with the help of a series transformer. The injection of an appropriate voltage component in the event of a voltage disturbance requires a certain amount of real and reactive power. Conventionally,DVR consists of an energy storage device, which supplies the required power over the limited duration of the sags. Large magnitude and long duration of sags lead to heavy financial investment in energy storage unit. To overcome this limitation, a single-phase back-to-back converter-based DVR is implemented inthis work, which eliminates energy storage requirement. The integration of series and shunt converter makes the DVR capable of bidirectional flow of energy. Therefore, the key advantage of this topology is its capability to compensate for long-term voltage sag and swell. Modelling of the DVR and its controller design is included in this paper. The effectiveness of control schemes, protection schemes and starting sequence of operation of DVR is verified through detailed simulation studies. A scaled down laboratory prototype of DVR is developed. The viability of these schemes is confirmed by the experimental results generated from the laboratory prototype. Various challenges faced during the prototype development and corresponding solutions are also discussed in this paper.

  18. The efficiency of nanotube formation on titanium anodized under voltage and current control in fluoride/glycerol electrolyte

    Science.gov (United States)

    Valota, A.; LeClere, D. J.; Hashimoto, T.; Skeldon, P.; Thompson, G. E.; Berger, S.; Kunze, J.; Schmuki, P.

    2008-09-01

    The formation of nanotubes on titanium is compared for anodizing under controlled voltage and controlled current in a fluoride/glycerol electrolyte. Rutherford backscattering spectroscopy and nuclear reaction analysis are employed to determine the film compositions. Film morphologies are examined by electron microscopy. The findings reveal films of approximate composition TiO2.0.15TiF4 that probably also contain derivatives of glycerol. Controlled voltage conditions resulted in more uniform final nanotube dimensions, for a particular charge density, and the highest efficiency of film growth, with the charge of the titanium in the film representing ~48% of the charge passed during anodizing. Under current control, the efficiency decreased from ~40% to ~23% with increase of the current density from 0.1 to 0.5 mA cm-2. Further, the thickness of the barrier layer was sometimes enhanced under current control, possibly due to a non-uniform current distribution and consequently elevated local temperature.

  19. 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...

  20. Electric Voltage Control as an Implementation of Neural Network Applications

    Directory of Open Access Journals (Sweden)

    A. A. Al-Rababah

    2008-01-01

    Full Text Available Present study was proposed the monitoring of mathematical model of electric voltage source with using neural network for application in control systems as sensor and command signal. The monitoring system, consist of toroidal choke or transformer with high saturated ferromagnetic cores. The input information we receive from current periodic curves. The current was distributed into Fourier or walsh series. The combination of these harmonics and their amplitude values determine monitoring voltage value directly. For increase of this system precision, the mathematical model was constructed on basis of partial differential quasi-stationary electromagnetic field equations and ordi-nary differential electromagnetic circuit equations combination.

  1. Persistent Hall voltages across thin planar charged quantum rings on the surface of a three-dimensional topological insulator

    Science.gov (United States)

    Durganandini, P.

    2016-03-01

    We study theoretically, the electromagnetic response due to localized charge current distributions above a topological insulator (coated with a thin ferromagnetic layer) using the electromagnetic SL(2,Z) duality symmetry. We show that the localized current induces an electric field which depends on the current —this is a manifestation of the topological magnetoelectric (TME) effect. We also show that if the charge carriers have spin, then they acquire Aharanov-Casher phases which depend on the current. As an application, we consider thin planar charged quantum rings with persistent currents on the surface of a TI and show that the TME manifests itself as persistent Hall voltages across the charged ring. If the spin is also taken into account, then persistent spin Hall voltages develop across the ring.

  2. Two-Stage Electric Vehicle Charging Coordination in Low Voltage Distribution Grids

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Pillai, Jayakrishnan Radhakrishna

    2014-01-01

    Increased environmental awareness in the recent years has encouraged rapid growth of renewable energy sources (RESs); especially solar PV and wind. One of the effective solutions to compensate intermittencies in generation from the RESs is to enable consumer participation in demand response (DR......). Being a sizable rated element, electric vehicles (EVs) can offer a great deal of demand flexibility in future intelligent grids. This paper first investigates and analyzes driving pattern and charging requirements of EVs. Secondly, a two-stage charging algorithm, namely local adaptive control...

  3. Voltage controlled resistor using quasi-floating-gate MOSFETs

    Directory of Open Access Journals (Sweden)

    Susheel Sharma

    2013-01-01

    Full Text Available A voltage controlled resistor (VCR using quasi-floating-gate MOSFETs (QFGMOS suitable for low voltage applications is presented. The performance of the VCR implemented with QFGMOS is compared with its floating-gate MOSFET (FGMOS version. It was found that QFGMOS offers better performance than FGMOS in terms of frequency response, offsets and chip area. The VCR using QFGMOS offers high bandwidth and low power dissipation and yields high value of resistance as compared to its FGMOS counterpart. The workability of the presented circuits was tested by PSpice simulations using level 3 parameters of 0.5μm CMOS technology with supply voltage of ± 0.75V. The simulations results were found to be in accordance with the theoretical predictions.

  4. Secondary control for reactive power sharing and voltage amplitude restoration in droop-controlled islanded microgrids

    DEFF Research Database (Denmark)

    Micallef, A.; Apap, M.; Spiteri Staines, C.

    2012-01-01

    This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. However...... and to restore the voltage deviations caused by the droop control. Primary droop control loops where implemented in the inverters to supply the real and reactive power. Simulation results are presented showing the feasibility of the proposed algorithm in achieving reactive power sharing between the inverters...... connected to the microgrid while simultaneously restoring the voltage deviations due to the droop control....

  5. Automatic Voltage Control (AVC) of Danish Transmission System - Concept design

    DEFF Research Database (Denmark)

    Qin, Nan; Abildgaard, Hans; Lund, P.

    2014-01-01

    , objectives, constraints, algorithms for optimal power flow and some special functions in particular systems, which inspires the concept design of a Danish AVC system to address the future challenges of voltage control. In the concept, the Danish AVC design is based on a centralized control scheme. All....... Another consequence is the public way of generally thinking green which have led to a national decision of undergrounding not only all of the Danish distribution system but also the future transmission system. These issues initiate the infrastructure constructions of the transmission system i.e. a large...... the substation loses the telecommunications to the control center. RPCs will be integrated to the AVC system as normative regulators in the later stage. Distributed generation units can be organized as virtual power plants and participate in voltage control at transmission level. Energinet.dk as the Danish TSO...

  6. Voltage Regulators for Photovoltaic Systems

    Science.gov (United States)

    Delombard, R.

    1986-01-01

    Two simple circuits developed to provide voltage regulation for highvoltage (i.e., is greater than 75 volts) and low-voltage (i.e., is less than 36 volts) photovoltaic/battery power systems. Use of these circuits results in voltage regulator small, low-cost, and reliable, with very low power dissipation. Simple oscillator circuit controls photovoltaic-array current to regulate system voltage and control battery charging. Circuit senses battery (and system) voltage and adjusts array current to keep battery voltage from exceeding maximum voltage.

  7. Impact of charge transport on current-voltage characteristics and power-conversion efficiency of organic solar cells.

    Science.gov (United States)

    Würfel, Uli; Neher, Dieter; Spies, Annika; Albrecht, Steve

    2015-04-24

    This work elucidates the impact of charge transport on the photovoltaic properties of organic solar cells. Here we show that the analysis of current-voltage curves of organic solar cells under illumination with the Shockley equation results in values for ideality factor, photocurrent and parallel resistance, which lack physical meaning. Drift-diffusion simulations for a wide range of charge-carrier mobilities and illumination intensities reveal significant carrier accumulation caused by poor transport properties, which is not included in the Shockley equation. As a consequence, the separation of the quasi Fermi levels in the organic photoactive layer (internal voltage) differs substantially from the external voltage for almost all conditions. We present a new analytical model, which considers carrier transport explicitly. The model shows excellent agreement with full drift-diffusion simulations over a wide range of mobilities and illumination intensities, making it suitable for realistic efficiency predictions for organic solar cells.

  8. Impact of charge transport on current–voltage characteristics and power-conversion efficiency of organic solar cells

    Science.gov (United States)

    Würfel, Uli; Neher, Dieter; Spies, Annika; Albrecht, Steve

    2015-01-01

    This work elucidates the impact of charge transport on the photovoltaic properties of organic solar cells. Here we show that the analysis of current–voltage curves of organic solar cells under illumination with the Shockley equation results in values for ideality factor, photocurrent and parallel resistance, which lack physical meaning. Drift-diffusion simulations for a wide range of charge-carrier mobilities and illumination intensities reveal significant carrier accumulation caused by poor transport properties, which is not included in the Shockley equation. As a consequence, the separation of the quasi Fermi levels in the organic photoactive layer (internal voltage) differs substantially from the external voltage for almost all conditions. We present a new analytical model, which considers carrier transport explicitly. The model shows excellent agreement with full drift-diffusion simulations over a wide range of mobilities and illumination intensities, making it suitable for realistic efficiency predictions for organic solar cells. PMID:25907581

  9. Gain Scheduling Control of an Islanded Microgrid Voltage

    Directory of Open Access Journals (Sweden)

    Haritza Camblong

    2014-07-01

    Full Text Available The aim of this research study has been to design a gain scheduling (GS digital controller in order to control the voltage of an islanded microgrid in the presence of fast varying loads (FVLs, and to compare it to a robust controller. The inverter which feeds the microgrid is connected to it through an inductance-capacitor-inductance (LCL filter. The oscillatory and nonlinear behaviour of the plant is analyzed in the whole operating zone. Afterwards, the design of the controllers which contain two loops in cascade are described. The first loop concerns the current control, while the second is linked to the voltage regulation. Two controllers, one defined as Robust and another one as GS controller, are designed for the two loops, emphasizing in their robustness and their ability to damp the oscillatory plant behaviour. To finish, some simulations are carried out to study and compare the two kinds of controllers in different operating points. The results show that both controllers damp the oscillatory behaviour of the plant in closed loop (CL, and that the GS controller ensures a better rejection of current disturbances from FVLs.

  10. Automatic charge control system for satellites

    Science.gov (United States)

    Shuman, B. M.; Cohen, H. A.

    1985-01-01

    The SCATHA and the ATS-5 and 6 spacecraft provided insights to the problem of spacecraft charging at geosychronous altitudes. Reduction of the levels of both absolute and differential charging was indicated, by the emission of low energy neutral plasma. It is appropriate to complete the transition from experimental results to the development of a system that will sense the state-of-charge of a spacecraft, and, when a predetermined threshold is reached, will respond automatically to reduce it. A development program was initiated utilizing sensors comparable to the proton electrostatic analyzer, the surface potential monitor, and the transient pulse monitor that flew in SCATHA, and combine these outputs through a microprocessor controller to operate a rapid-start, low energy plasma source.

  11. Computer Controlled High Precise,High Voltage Pules Generator

    Institute of Scientific and Technical Information of China (English)

    但果; 邹积岩; 丛吉远; 董恩源

    2003-01-01

    High precise, high voltage pulse generator made up of high-power IGBT and pulse transformers controlled by a computer are described. A simple main circuit topology employed in this pulse generator can reduce the cost meanwhile it still meets special requirements for pulsed electric fields (PEFs) in food process. The pulse generator utilizes a complex programmable logic device (CPLD) to generate trigger signals. Pulse-frequency, pulse-width and pulse-number are controlled via RS232 bus by a computer. The high voltage pulse generator well suits to the application for fluid food non-thermal effect in pulsed electric fields, for it can increase and decrease by the step length 1.

  12. Chaotic dynamics of a Chua's system with voltage controllability

    Science.gov (United States)

    Heo, Yun Seok; Jung, Jin Woo; Kim, Ji Man; Jo, Mun Kyu; Song, Han Jung

    2012-04-01

    This paper presents an integrated circuit oriented Chua's chaotic system with voltage controllability. The proposed chaotic system consists of an OTA (Operational Transconductance Amplifier)-based ground inductor, two passive capacitors, a MOS (Metal-Oxide-Semiconductor)-based active resistor and an OTA-based Chua's diode with negative nonlinearity. A SPICE (Simulation Program with Integrated Circuit Emphasis) circuit analysis using 0.5-µm CMOS (Complementary Metal-Oxide-Semiconductor) process parameters was performed for the chaotic dynamics, such as the time waveform and the attractor plot. We confirmed that the chaotic behaviors of the system could be controlled by using the gate voltage of the MOS-based active resistor. Also, various chaotic dynamics of the circuit were analyzed for various MOS sizes of the OTA in the Chua's diode.

  13. Intelligent distributed voltage control system for smart grid application

    Energy Technology Data Exchange (ETDEWEB)

    Sajadi, Amirhossein [Warsaw Univ. of Technology (Poland); Ariatabar, Mitra [RWTH Aachen Univ. (Germany)

    2012-07-01

    Increasing penetration of the renewable energy source (RES) units in distribution networks particularly due to nonlinear and unpredictable nature of renewable units brings up new challenges in different aspects of electricity network, which leads to more complex power systems. Multi-agent system is consisting of agents which are capable to perceive environment that they are located in and to reacts with each other by communication infrastructure in order to achieve overall goals. In this paper an approach to control the voltage based on in the power distribution system is proposed and discussed. Therefore, a multi-agent system has been integrated with artificial intelligence to come up with fuzzy multi-agent based system. The proposed control scheme is deployed to a smart distribution system consisting distribution generation units, modelled in MATLAB/Simulink, to evaluate its effectiveness. The simulation results show how proposed system can regulate voltage in smart distribution feeders. (orig.)

  14. Voltage controlled optics of a monolayer semiconductor quantum emitter

    Science.gov (United States)

    Chakraborty, Chitraleema; Goodfellow, Kenneth; Kinnischtzke, Laura; Vamivakas, Nick; University of Rochester Team

    2015-03-01

    Two-dimensional atomically thin materials are being actively investigated for next generation optoelectronic devices. Particularly exciting are transition metal dichalcogenides (TMDC) since these materials exhibit a band gap, and support valley specific exciton mediated optical transitions. In this work we report the observation of single photon emission in the TMDC tungsten diselenide. We present magneto-optical spectroscopy results and demonstrate voltage controlled photoluminescence of these localized quantum emitters.

  15. A charge coupled device camera with electron decelerator for intermediate voltage electron microscopy.

    Science.gov (United States)

    Downing, Kenneth H; Mooney, Paul E

    2008-04-01

    Electron microscopists are increasingly turning to intermediate voltage electron microscopes (IVEMs) operating at 300-400 kV for a wide range of studies. They are also increasingly taking advantage of slow-scan charge coupled device (CCD) cameras, which have become widely used on electron microscopes. Under some conditions, CCDs provide an improvement in data quality over photographic film, as well as the many advantages of direct digital readout. However, CCD performance is seriously degraded on IVEMs compared to the more conventional 100 kV microscopes. In order to increase the efficiency and quality of data recording on IVEMs, we have developed a CCD camera system in which the electrons are decelerated to below 100 kV before impacting the camera, resulting in greatly improved performance in both signal quality and resolution compared to other CCDs used in electron microscopy. These improvements will allow high-quality image and diffraction data to be collected directly with the CCD, enabling improvements in data collection for applications including high-resolution electron crystallography, single particle reconstruction of protein structures, tomographic studies of cell ultrastructure, and remote microscope operation. This approach will enable us to use even larger format CCD chips that are being developed with smaller pixels.

  16. Single-artificial-atom lasing using a voltage-biased superconducting charge qubit

    Energy Technology Data Exchange (ETDEWEB)

    Ashhab, S; Johansson, J R; Zagoskin, A M; Nori, Franco [Frontier Research System, Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198 (Japan)], E-mail: ashhab@riken.jp

    2009-02-15

    We consider a system composed of a single artificial atom coupled to a cavity mode. The artificial atom is biased such that the most dominant relaxation process in the system takes the atom from its ground state to its excited state, thus ensuring population inversion. A recent experimental manifestation of this situation was achieved using a voltage-biased superconducting charge qubit. Even under the condition of 'inverted relaxation', lasing action can be suppressed if the 'relaxation' rate is larger than a certain threshold value. Using simple transition-rate arguments and a semiclassical calculation, we derive analytic expressions for the lasing suppression condition and the state of the cavity in both the lasing and suppressed-lasing regimes. The results of numerical calculations agree very well with the analytically derived results. We start by analyzing a simplified two-level-atom model, and we then analyze a three-level-atom model that should describe accurately the recently realized superconducting artificial-atom laser.

  17. PI controller scheme for charge balance in implantable electrical stimulators

    Indian Academy of Sciences (India)

    C Rathna

    2016-01-01

    Electrical stimulation has been used in a wide variety of medical implant applications. In all of these applications, due to safety concerns, maintaining charge balance becomes a critically important issue that needs to be addressed at the design stage. It is important that charge balancing schemes be robust to circuit (process) and load impedance variations, and at the same time must also lend themselves to miniaturization. In this communication, simulation studies on the effectiveness of using Proportional Integral (P-I) control schemes for managing charge balance in electrical stimulation are presented. The adaptation of the P-I control scheme to implant circuits leads to two possible circuit realizations in the analog domain. The governing equations for these realizations are approximated to simple linear equations. Considering typical circuit and tissue parameter values and their expected uncertainties, Matlab as well as circuit simulations have been carried out. Simulation results presented indicate that the tissue voltages settle to well below 20% of the safe levels and within about 20 stimulations cycles, thus confirming the validity and robustness of the proposed schemes.

  18. OPTIMAL CHARGING OF ELECTRICAL VEHICLES IN THE SMART CITY FOR LOSS MINIMIZATION AND VOLTAGE IMPROVEMENT

    Directory of Open Access Journals (Sweden)

    Adrian Toni Radu

    2017-06-01

    Full Text Available The world is two-thirds of the way through a century-long cycle of rapid urbanisation, at the end of which more than 70% of people will live in cities (World Health Organization, 2014. The urban transformation has become a major contributor to economic, demographic, social and environmental change. Electric vehicles (EVs have become increasingly popular over the last few years and are considered as an important means to mitigate air pollution problems in big cities around the world. With their onboard batteries, EVs also present an opportunity to serve as a demand response tool in supporting future smart grid where there is usually high penetration level of renewable energy (RE sources. In this paper, we consider the coordinated charging control of electrical vehicles in the charging stations. The goals are to illustrate how the integration of EVs at the urban area improve the overall load schedule of the distribution network.

  19. Two-Level Control for Fast Electrical Vehicle Charging Stations with Multi Flywheel Energy Storage System

    DEFF Research Database (Denmark)

    SUN, BO; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2015-01-01

    This paper applies a hierarchical control for a fast charging station (FCS) composed of paralleled PWM rectifier and dedicated paralleled multiple flywheel energy storage systems (FESSs), in order to mitigate peak power shock on grid caused by sudden connection of electrical vehicle (EV) chargers....... Distributed DC-bus signaling (DBS) and method resistive virtual impedance are employed in the power coordination of grid and flywheel converters, and a centralized secondary controller generates DC voltage correction term to adjust the local voltage set point. The control system is able to realize the power...... control strategy....

  20. Contributions of counter-charge in a potassium channel voltage-sensor domain

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Galpin, Jason D; Niciforovic, Ana P

    2011-01-01

    Voltage-sensor domains couple membrane potential to conformational changes in voltage-gated ion channels and phosphatases. Highly coevolved acidic and aromatic side chains assist the transfer of cationic side chains across the transmembrane electric field during voltage sensing. We investigated...

  1. Combining Market-Based Control with Distribution Grid Constraints when Coordinating Electric Vehicle Charging

    Directory of Open Access Journals (Sweden)

    Geert Deconinck

    2015-12-01

    Full Text Available The charging of electric vehicles (EVs impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based control algorithm to coordinate the charging of these vehicles, in order to minimize the costs. In such an optimization, the operational parameters of the distribution grid, to which the EVs are connected, are not considered. This can lead to violations of the technical constraints of the grid (e.g., under-voltage, phase unbalances; for example, because many vehicles start charging simultaneously when the price is low. An optimization that simultaneously takes the economic and technical aspects into account is complex, because it has to combine time-driven control at the market level with event-driven control at the operational level. Different case studies investigate under which circumstances the market-based control, which coordinates EV charging, conflicts with the operational constraints of the distribution grid. Especially in weak grids, phase unbalance and voltage issues arise with a high share of EVs. A low-level voltage droop controller at the charging point of the EV can be used to avoid many grid constraint violations, by reducing the charge power if the local voltage is too low. While this action implies a deviation from the cost-optimal operating point, it is shown that this has a very limited impact on the business case of an aggregator, and is able to comply with the technical distribution grid constraints, even in weak distribution grids with many EVs.

  2. Capacitor charging FET switcher with controller to adjust pulse width

    Science.gov (United States)

    Mihalka, A. M.

    1986-04-01

    A switching power supply includes an FET full bridge, a controller to drive the FETs, a programmable controller to dynamically control final output current by adjusting pulse width, and a variety of protective systems, including an overcurrent latch for current control. Power MOSFETS are switched at a variable frequency from 20 to 50 kHz to charge a capacitor load from 0 to 6 kV. A ferrite transformer steps up the dc input. The transformer primary is a full bridge configuration with the FET switches and the secondary is fed into a high voltage full wave rectifier whose output is connected directly to the energy storage capacitor. The peak current is held constant by varying the pulse width using predetermined timing resistors and counting pulses. The pulse width is increased as the capacitor charges to maintain peak current. A digital ripple counter counts pulses, and after the desired number is reached, an up-counter is clocked. The up-counter output is decoded to choose among different resistors used to discharge a timing capacitor, thereby determining the pulse width. A current latch shuts down the supply on overcurrent due to either excessive pulse width causing transformer saturation or a major bridge fault, i.e., FET or transformer failure, or failure of the drive circuitry.

  3. Voltage Regulation by Phase Commutation Control Running On FPAA

    Directory of Open Access Journals (Sweden)

    Ckristian. R. Durán-Blanco

    2013-11-01

    Full Text Available In this article we present a control scheme for triggering a SCR-based rectifier circuit. As implementation platform we use a field-programmable-analog-array device (FPAA that allows the development of algorithms for proportional, PID and sliding mode (SMC control techniques. Results show good performance of tested techniques to avoid effects of perturbations over the circuit load, by keeping regulated the output voltage. This suggests the potential use of the proposed technology for applications of reconfigurable hardware in power electronics.

  4. Voltage Sags Ride-Through of Motion Sensorless Controlled PMSG for Wind Turbines

    DEFF Research Database (Denmark)

    Fatu, Marius; Lascu, Cristian; Andreescu, Gheorghe-Daniel;

    2007-01-01

    is used to robustly estimate the grid voltage positivesequence for control in the case of asymmetric voltages. The paper investigates the ride-through performance of this system during asymmetric power grid voltage sags. Design details for various parts of the control system are presented, together...... with experimental results for single-, two-, and three-phase voltage source sags. Smooth transition through asymmetric voltage sags is demonstrated by all experiments....

  5. Microscale vortex laser with controlled topological charge

    Science.gov (United States)

    Wang, Xing-Yuan; Chen, Hua-Zhou; Li, Ying; Li, Bo; Ma, Ren-Min

    2016-12-01

    A microscale vortex laser is a new type of coherent light source with small footprint that can directly generate vector vortex beams. However, a microscale laser with controlled topological charge, which is crucial for virtually any of its application, is still unrevealed. Here we present a microscale vortex laser with controlled topological charge. The vortex laser eigenmode was synthesized in a metamaterial engineered non-Hermitian micro-ring cavity system at exceptional point. We also show that the vortex laser cavity can operate at exceptional point stably to lase under optical pumping. The microscale vortex laser with controlled topological charge can serve as a unique and general building block for next-generation photonic integrated circuits and coherent vortex beam sources. The method we used here can be employed to generate lasing eigenmode with other complex functionalities. Project supported by the “Youth 1000 Talent Plan” Fund, Ministry of Education of China (Grant No. 201421) and the National Natural Science Foundation of China (Grant Nos. 11574012 and 61521004).

  6. Network based management for multiplexed electric vehicle charging

    Energy Technology Data Exchange (ETDEWEB)

    Gadh, Rajit; Chung, Ching Yen; Qui, Li

    2017-04-11

    A system for multiplexing charging of electric vehicles, comprising a server coupled to a plurality of charging control modules over a network. Each of said charging modules being connected to a voltage source such that each charging control module is configured to regulate distribution of voltage from the voltage source to an electric vehicle coupled to the charging control module. Data collection and control software is provided on the server for identifying a plurality of electric vehicles coupled to the plurality of charging control modules and selectively distributing charging of the plurality of charging control modules to multiplex distribution of voltage to the plurality of electric vehicles.

  7. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  8. A New Secondary Control Approach for Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Davari, Pooya;

    2016-01-01

    feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new...

  9. A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid

    DEFF Research Database (Denmark)

    Wang, Yanbo; Tan, Yongdong; Chen, Zhe

    2014-01-01

    This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage opt...

  10. Control Strategy for Cascaded Medium - High Voltage STATCOM

    Directory of Open Access Journals (Sweden)

    Libing Chen

    2013-12-01

    Full Text Available Control strategy is researched for cascaded medium high static synchronous compensator to provide synthetic compensation ability of reactive power, harmonics and asymmetric currents. Basing on selective harmonic compensation strategy, a reference current detection method utilizing the combination of synchronous reference frame transformation and discrete Fourier transformation is proposed. The tracking control of instruction current is implemented by multi-carrier pulse width modulation (PWM. In allusion to the multi-carrier PWM, the capacitor voltage balancing control at the dc side is realized by a type of software based on the energy balance principle of the inverter bridge. The proposed control strategy is convenient for engineering implementation given its low calculation burden and simplicity. The effectiveness of the proposed control strategy is proven by both simulation and experimental results.

  11. Review of multilevel voltage source inverter topologies and control schemes

    Energy Technology Data Exchange (ETDEWEB)

    Colak, Ilhami [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey); Kabalci, Ersan, E-mail: kabalci@nevsehir.edu.t [Department of Technical Programs, Vocational Collage of Haci Bektas, Nevsehir University, Hacibektas, Nevsehir 50800 (Turkey); Bayindir, Ramazan [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey)

    2011-02-15

    In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.

  12. Hybrid zero-voltage switching (ZVS) control for power inverters

    Science.gov (United States)

    Amirahmadi, Ahmadreza; Hu, Haibing; Batarseh, Issa

    2016-11-01

    A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit.

  13. Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage DC gun

    CERN Document Server

    Bazarov, Ivan V; Gulliford, Colwyn; Li, Yulin; Liu, Xianghong; Sinclair, Charles K; Soong, Ken; Hannon, Fay

    2008-01-01

    We present a comparison between space charge calculations and direct measurements of the transverse phase space for space charge dominated electron bunches after a high voltage photoemission DC gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit setup for a set of parameters such as charge per bunch and the solenoid current. The data is compared with detailed simulations using 3D space charge codes GPT and Parmela3D with initial particle distributions created from the measured transverse and temporal laser profiles. Beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach the theoretical maximum set by the thermal energy and accelerating field at the photocathode.

  14. Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage dc gun

    Directory of Open Access Journals (Sweden)

    Ivan V. Bazarov

    2008-10-01

    Full Text Available We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The data are compared with detailed simulations using the 3D space charge codes GPT and Parmela3D. The initial particle distributions were generated from measured transverse and temporal laser beam profiles at the photocathode. The beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach within a factor of 2 the theoretical maximum set by the thermal energy and the accelerating field at the photocathode.

  15. DC-bus voltage control of grid-connected voltage source converter by using space vector modulated direct power control under unbalanced network conditions

    DEFF Research Database (Denmark)

    Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan

    2013-01-01

    Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this......Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load....... In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...

  16. Voltage controlled magnetism in 3d transitional metals

    Science.gov (United States)

    Wang, Weigang

    2015-03-01

    Despite having attracted much attention in multiferroic materials and diluted magnetic semiconductors, the impact of an electric field on the magnetic properties remains largely unknown in 3d transitional ferromagnets (FMs) until recent years. A great deal of effort has been focused on the voltage-controlled magnetic anisotropy (VCMA) effect where the modulation of anisotropy field is understood by the change of electron density among different d orbitals of FMs in the presence of an electric field. Here we demonstrate another approach to alter the magnetism by electrically controlling the oxidation state of the 3d FM at the FM/oxide interface. The thin FM film sandwiched between a heavy metal layer and a gate oxide can be reversibly changed from an optimally-oxidized state with a strong perpendicular magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy, or to a fully-oxidized state with nearly zero magnetization, depending on the polarity and time duration of the applied electric fields. This is a voltage controlled magnetism (VCM) effect, where both the saturation magnetization and anisotropy field of the 3d FM layer can be simultaneously controlled by voltage in a non-volatile fashion. We will also discuss the impact of this VCM effect on magnetic tunnel junctions and spin Hall switching experiments. This work, in collaboration with C. Bi, Y.H. Liu, T. Newhouse-Illige, M. Xu, M. Rosales, J.W. Freeland, O. Mryasov, S. Zhang, and S.G.E. te Velthuis, was supported in part by NSF (ECCS-1310338) and by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  17. Strategies for Voltage Control and Transient Stability Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hiskens, Ian A.

    2013-09-25

    As wind generation grows, its influence on power system performance will becoming increasingly noticeable. Wind generation di ffers from traditional forms of generation in numerous ways though, motivating the need to reconsider the usual approaches to power system assessment and performance enhancement. The project has investigated the impact of wind generation on transient stability and voltage control, identifying and addressing issues at three distinct levels of the power system: 1) at the device level, the physical characteristics of wind turbine generators (WTGs) are quite unlike those of synchronous machines, 2) at the wind-farm level, the provision of reactive support is achieved through coordination of numerous dissimilar devices, rather than straightforward generator control, and 3) from a systems perspective, the location of wind-farms on the sub-transmission network, coupled with the variability inherent in their power output, can cause complex voltage control issues. The project has sought to develop a thorough understanding of the dynamic behaviour of type-3 WTGs, and in particular the WECC generic model. The behaviour of such models is governed by interactions between the continuous dynamics of state variables and discrete events associated with limits. It was shown that these interactions can be quite complex, and may lead to switching deadlock that prevents continuation of the trajectory. Switching hysteresis was proposed for eliminating deadlock situations. Various type-3 WTG models include control blocks that duplicate integrators. It was shown that this leads to non-uniqueness in the conditions governing steady-state, and may result in pre- and post-disturbance equilibria not coinciding. It also gives rise to a zero eigenvalue in the linearized WTG model. In order to eliminate the anomalous behaviour revealed through this investigation, WECC has now released a new generic model for type-3 WTGs. Wind-farms typically incorporate a variety of

  18. A PC-controlled voltage pulse generator for electroanalytical applications

    Science.gov (United States)

    Heredia-López, Francisco J.; Góngora-Alfaro, José L.; Alvarez-Cervera, Fernando J.; Bata-García, José Luis

    1997-04-01

    We present the design of a voltage pulse generator controlled by an IBM or compatible AT Personal Computer (PC) capable of synthesizing some of the voltage pulse wave forms commonly used in electrochemical studies. The included signals are: differential pulse voltametry, differential normal pulse voltametry, and differential pulse amperometry. Additionally, a triangular wave form and a constant-voltage signal, used in the pretreatment of carbon fiber microelectrodes for neurochemical analysis, are also available. Operating the generator imposes a minimum of restrictions on the specification of the duration, amplitude, and type of wave shapes. Low-cost PC-based design allows for compatibility, portability, and versatility. The operating ranges of the wave form parameters for the three voltametric signals are: initial voltage, -0.9-+0.9 V; step amplitude, 0.1-900 mV; period, 6 ms-60 s; measuring pulse amplitude, 0.1-900 mV; measuring pulse duration, 2 ms-20 s; prepulse duration, 2 ms-20 s. In the electrode pretreatment mode, the operating ranges are: amplitude, 0-±5 V; duration, unlimited; frequency, 15-240 Hz. The generator uses its own time base for the generation of all signals, thereby rendering it independent of processor clock speed or power-line frequency. The results of the experimental evaluation indicate that the system is accurate within ±10% of the expected values, taking into account the errors associated with the signal synthesis and the digitizing process. The maximum achievable scan rate is 500 V/s, and the highest frequency for the triangular wave form is 240 Hz. Therefore, the pulse generator could be used for fast cyclic voltametry (FCV). FCV and other wave forms could be added through software modules, without any hardware changes. We conclude that the PC-based electrochemistry pulse generator represents an economical and flexible alternative for electroanalytical applications.

  19. S1-S3 counter charges in the voltage sensor module of a mammalian sodium channel regulate fast inactivation.

    Science.gov (United States)

    Groome, James R; Winston, Vern

    2013-05-01

    The movement of positively charged S4 segments through the electric field drives the voltage-dependent gating of ion channels. Studies of prokaryotic sodium channels provide a mechanistic view of activation facilitated by electrostatic interactions of negatively charged residues in S1 and S2 segments, with positive counterparts in the S4 segment. In mammalian sodium channels, S4 segments promote domain-specific functions that include activation and several forms of inactivation. We tested the idea that S1-S3 countercharges regulate eukaryotic sodium channel functions, including fast inactivation. Using structural data provided by bacterial channels, we constructed homology models of the S1-S4 voltage sensor module (VSM) for each domain of the mammalian skeletal muscle sodium channel hNaV1.4. These show that side chains of putative countercharges in hNaV1.4 are oriented toward the positive charge complement of S4. We used mutagenesis to define the roles of conserved residues in the extracellular negative charge cluster (ENC), hydrophobic charge region (HCR), and intracellular negative charge cluster (INC). Activation was inhibited with charge-reversing VSM mutations in domains I-III. Charge reversal of ENC residues in domains III (E1051R, D1069K) and IV (E1373K, N1389K) destabilized fast inactivation by decreasing its probability, slowing entry, and accelerating recovery. Several INC mutations increased inactivation from closed states and slowed recovery. Our results extend the functional characterization of VSM countercharges to fast inactivation, and support the premise that these residues play a critical role in domain-specific gating transitions for a mammalian sodium channel.

  20. DC-link Voltage Control to Compensate Voltage Deviation for PV–BESSs Integrated System in Low-Voltage (LV Networks

    Directory of Open Access Journals (Sweden)

    Lee Gyu-sub

    2016-01-01

    Full Text Available The exhaustion of fossil fuel and the greenhouse gas emission are one of the most significant energy and environmental issues, respectively. Photovoltaic (PV generators and battery energy storage systems (BESSs have been significantly increased for recent years. The BESSs are mainly used for smoothing active power fluctuation of the PV. In this paper, PV–BESSs integration of two DC/DC converters and one AC/DC converter is investigated and DC-link voltage control to compensate the AC voltage deviation is proposed for the PV‒BESS system in low-voltage (LV networks.

  1. Comparative Study of Online Open Circuit Voltage Estimation Techniques for State of Charge Estimation of Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Hicham Chaoui

    2017-04-01

    Full Text Available Online estimation techniques are extensively used to determine the parameters of various uncertain dynamic systems. In this paper, online estimation of the open-circuit voltage (OCV of lithium-ion batteries is proposed by two different adaptive filtering methods (i.e., recursive least square, RLS, and least mean square, LMS, along with an adaptive observer. The proposed techniques use the battery’s terminal voltage and current to estimate the OCV, which is correlated to the state of charge (SOC. Experimental results highlight the effectiveness of the proposed methods in online estimation at different charge/discharge conditions and temperatures. The comparative study illustrates the advantages and limitations of each online estimation method.

  2. Secondary Control Scheme for Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

    2012-01-01

    The concept of microgrid hierarchical control is presented recently. In this paper, a hierarchical scheme is proposed which includes primary and secondary control levels. The primary level comprises distributed generators (DGs) local controllers. The local controllers mainly consist of power......, voltage and current controllers, and virtual impedance control loop. The central secondary controller is designed to manage the compensation of voltage unbalance at the point of common coupling (PCC) in an islanded microgrid. Unbalance compensation is achieved by sending proper control signals to the DGs...

  3. Symmetry-Breaking Charge Transfer in a Zinc Chlorodipyrrin Acceptor for High Open Circuit Voltage Organic Photovoltaics

    KAUST Repository

    Bartynski, Andrew N.

    2015-04-29

    © 2015 American Chemical Society. Low open-circuit voltages significantly limit the power conversion efficiency of organic photovoltaic devices. Typical strategies to enhance the open-circuit voltage involve tuning the HOMO and LUMO positions of the donor (D) and acceptor (A), respectively, to increase the interfacial energy gap or to tailor the donor or acceptor structure at the D/A interface. Here, we present an alternative approach to improve the open-circuit voltage through the use of a zinc chlorodipyrrin, ZCl [bis(dodecachloro-5-mesityldipyrrinato)zinc], as an acceptor, which undergoes symmetry-breaking charge transfer (CT) at the donor/acceptor interface. DBP/ZCl cells exhibit open-circuit voltages of 1.33 V compared to 0.88 V for analogous tetraphenyldibenzoperyflanthrene (DBP)/C60-based devices. Charge transfer state energies measured by Fourier-transform photocurrent spectroscopy and electroluminescence show that C60 forms a CT state of 1.45 ± 0.05 eV in a DBP/C60-based organic photovoltaic device, while ZCl as acceptor gives a CT state energy of 1.70 ± 0.05 eV in the corresponding device structure. In the ZCl device this results in an energetic loss between ECT and qVOC of 0.37 eV, substantially less than the 0.6 eV typically observed for organic systems and equal to the recombination losses seen in high-efficiency Si and GaAs devices. The substantial increase in open-circuit voltage and reduction in recombination losses for devices utilizing ZCl demonstrate the great promise of symmetry-breaking charge transfer in organic photovoltaic devices.

  4. 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...

  5. Design and Development of a control system for the Drift Tube Chamber High Voltage Power Supply

    CERN Document Server

    Leon Vega, Luis Gerardo

    2017-01-01

    This paper contains information related to the design and development of a control and data acquisition manager implemented in WinCC, a Siemens SCADA system. The goal was to manage a CAEN HV (High Voltage) system for powering a Drift Tube (DT) chamber of the CMS experiment. Basically, this manager consists of two sections: a friendly user interface and powerful scripts to manage the back-end. It is in charge of adjusting the power supply settings to the correct values needed for the DT Chamber operations (ON, OFF, Standby), depending of the requirements of the operator, managing automatically all the transition process. Also, the manager is in charge of configuring the archiving process for acquiring data and providing the history of the system. It also implements the monitoring of the status of each connected channel, alerting in case it is needed.

  6. A New Secondary Control Approach for Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Davari, Pooya

    2016-01-01

    In this paper the effect of secondary controller on voltage regulation in dc Micro-Grids (MGs) is studied. Basically, centralized or decentralized secondary controller has been employed to regulate the voltage drop raised by the primary controller. However, in the case of high capacity MGs and long...... feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new...... voltage regulation strategy is proposed to regulate the voltage of MG by employing the average voltage of identified busses, which are determined by the proposed modal analysis. Numerical steady state analysis and preliminary simulation results validate effectiveness of the proposed scheme. Furthermore...

  7. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    Science.gov (United States)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Xie, Qin; Ren, Chengyan; Shao, Tao

    2017-10-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level.

  8. 30 CFR 77.515 - Bare signal or control wires; voltage.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bare signal or control wires; voltage. 77.515... COAL MINES Electrical Equipment-General § 77.515 Bare signal or control wires; voltage. The voltage on bare signal or control wires accessible to personal contact shall not exceed 40 volts. ...

  9. Design and Analysis of a Slope Voltage Control for a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Martínez, J.; Kjær, P. C.; Rodriguez, Pedro

    2012-01-01

    This paper addresses a detailed design of a wind power plant and turbine slope voltage control in the presence of communication delays for a wide short-circuit ratio range operation. The implemented voltage control scheme is based upon the secondary voltage control concept, which offers fast...

  10. Controllable transition from positive space charge to negative space charge in an inverted cylindrical magnetron

    Energy Technology Data Exchange (ETDEWEB)

    Rane, R., E-mail: ramu@ipr.res.in; Ranjan, M.; Mukherjee, S. [FCIPT, Institute for Plasma Research, Gandhinagar-382044 (India); Bandyopadhyay, M. [ITER-India, Institute for Plasma Research, Gandhinagar-382044 (India)

    2016-01-15

    The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode. It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lower magnetic field.

  11. Assessment of the operating conditions of coordinated Q-V controller within secondary voltage control system

    Directory of Open Access Journals (Sweden)

    Arnautović Dušan

    2014-01-01

    Full Text Available The paper, discusses the possibility to use coordinated Q-V controller (CQVC to perform secondary voltage control at the power plant level. The CQVC performs the coordination of the synchronous generators' (SG reactive power outputs in order to maintain the same total reactive power delivered by the steam power plant (SPP, while at the same time maintaining a constant voltage with programmed reactive droop characteristic at the SPP HV busbar. This busbar is the natural pilot node for secondary voltage control at HV level as the node with maximum power production and maximum power consumption. In addition to voltage control, the CQVC maintains the uniform allocation of reactive power reserves at all SGs in the power plant. This is accomplished by setting the reactive power of each SG at given operating point in accordance to the available reactive power of the same SG at that point. Different limitations imposed by unit's and plant equipment are superimposed on original SG operating chart (provided by the manufacturer in order to establish realistic limits of SG operation at given operating point. The CQVC facilitates: i practical implementation of secondary voltage control in power system, as it is capable of ensuring delivery of reactive power as requested by regional/voltage control while maintaining voltage at system pilot node, ii the full deployment of available reactive power of SGs which in turn contributes to system stability, iii assessment of the reactive power impact/contribution of each generator in providing voltage control as ancillary service. Furthermore, it is also possible to use CQVC to pricing reactive power production cost at each SG involved and to design reactive power bidding structure for transmission network devices by using recorded data. Practical exploitation experience acquired during CQVC continuous operation for over two years enabled implementation of the optimal setting of reference voltage and droop on daily

  12. Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2013-01-01

    Full Text Available A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

  13. ZnO/NiO diode-based charge-trapping layer for flash memory featuring low-voltage operation.

    Science.gov (United States)

    Sun, Chergn-En; Chen, Chin-Yu; Chu, Ka-Lip; Shen, Yung-Shao; Lin, Chia-Chun; Wu, Yung-Hsien

    2015-04-01

    A stacked oxide semiconductor of n-type ZnO/p-type NiO with diode behavior was proposed as the novel charge-trapping layer to enable low-voltage flash memory for green electronics. The memory performance outperforms that of other devices with high κ and a nanocrystal-based charge-trapping layer in terms of a large hysteresis memory window of 2.02 V with ±3 V program/erase voltage, a high operation speed of 1.88 V threshold voltage shift by erasing at -4 V for 1 ms, negligible memory window degradation up to 10(5) operation cycles, and 16.2% charge loss after 10 years of operation at 85 °C. The promising electrical characteristics can be explained by the negative conduction band offset with respect to Si of ZnO that is beneficial to electron injection and storage, the large number of trapping sites of NiO that act as other good storage media, and most importantly the built-in electric field between n-type ZnO and p-type NiO that provides a favorable electric field for program and erase operation. The process of diode-based flash memory is fully compatible with incumbent VLSI technology, and utilization of the built-in electric field ushers in a new avenue of accomplishing green flash memory.

  14. Low-Voltage Consumption Coordination for Loss Minimization and Voltage Control

    DEFF Research Database (Denmark)

    Juelsgaard, Morten; Sloth, Christoffer; Wisniewski, Rafal

    2014-01-01

    This work presents a strategy for minimizing active power losses in low-voltage grids, by coordinating the consumption of electric vehicles and power generation from solar panels. We show that minimizing losses, also reduces voltage variations, and illustrate how this may be employed for increasing...... the number of electric vehicles and photovoltaic systems in the grid without violating grid constraints....

  15. Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

    Energy Technology Data Exchange (ETDEWEB)

    Sangiao, S. [Service de Physique de l' Etat Condensé, CEA Saclay, DSM/IRAMIS/SPEC, bat 772, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France); Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Fundación ARAID, 50018 Zaragoza (Spain); De Teresa, J. M. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, Facultad de Ciencias, 50009 Zaragoza (Spain); Morellon, L.; Martinez-Velarte, M. C. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Lucas, I. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Fundación ARAID, 50018 Zaragoza (Spain); Viret, M., E-mail: michel.viret@cea.fr [Service de Physique de l' Etat Condensé, CEA Saclay, DSM/IRAMIS/SPEC, bat 772, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France)

    2015-04-27

    We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the “Inverse Rashba Edelstein Effect” (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence.

  16. Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

    Directory of Open Access Journals (Sweden)

    Abdul Sattar Larik

    2011-01-01

    Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

  17. Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor

    Science.gov (United States)

    Smet, J. H.; Deutschmann, R. A.; Ertl, F.; Wegscheider, W.; Abstreiter, G.; von Klitzing, K.

    2003-01-01

    Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with applied voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for information processing and fundamental solid-state physics issues. Here, we report procedures that carry out the controlled transfer of spin angular momentum between electrons-confined to two dimensions and subjected to a perpendicular magnetic field-and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and ‘read-out’. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron-electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage.

  18. Voltage control and protection in electrical power systems from system components to wide-area control

    CERN Document Server

    Corsi, Sandro

    2015-01-01

    Based on the author’s twenty years of experience, this book shows the practicality of modern, conceptually new, wide area voltage control in transmission and distribution smart grids, in detail. Evidence is given of the great advantages of this approach, as well as what can be gained by new control functionalities which modern technologies now available can provide. The distinction between solutions of wide area voltage regulation (V-WAR) and wide area voltage protection (V-WAP) are presented, demonstrating the proper synergy between them when they operate on the same power system as well as the simplicity and effectiveness of the protection solution in this case. The author provides an overview and detailed descriptions of voltage controls, distinguishing between generalities of underdeveloped, on-field operating applications and modern and available automatic control solutions, which are as yet not sufficiently known or perceived for what they are: practical, high-performance and reliable solutions. At th...

  19. Distributed Cooperative Control of Multi Flywheel Energy Storage System for Electrical Vehicle Fast Charging Stations

    DEFF Research Database (Denmark)

    Sun, Bo; Dragicevic, Tomislav; Quintero, Juan Carlos Vasquez

    2015-01-01

    Plug-in electrical vehicles will play a critical role in future smart grid and sudden connection of electrical vehicles chargers may cause huge power-peaks with high slew-rates on grid. In order to cope with this issue, this paper applies a distributed cooperative control for fast charging station...... consensus based voltage observer by communicating with its neighbors. The control system can realize the power balancing and DC voltage regulation with low reliance on communications. Finally, real-time hardware-in-the-loop results have been reported in order to verify the feasibility of proposed approach....

  20. Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics

    Science.gov (United States)

    Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí i García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

    1998-02-01

    ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

  1. A New Approach to HVDC Grid Voltage Control Based on Generalized State Feedback

    DEFF Research Database (Denmark)

    Beerten, Jef; Eriksson, Robert; Van Hertem, Dirk

    2014-01-01

    In this paper, a new approach to DC voltage control in a High Voltage Direct Current (HVDC) grid is introduced. In an HVDC grid, the power sharing after a converter outage can be influenced by the droop control values. However, when relying on a local feedback signal, the DC voltage drops...

  2. Coordinated Voltage Control Scheme for SEIG-Based Wind Park Utilizing Substation STATCOM and ULTC Transformer

    DEFF Research Database (Denmark)

    S. El Moursi, Mohamed; Bak-Jensen, Birgitte; Abdel-Rahman, Mansour Hassan

    2011-01-01

    and optimal tracking secondary voltage control for wind parks based on self-excited induction generators which comprise STATCOM and under-load tap changer (ULTC) substation transformers. The voltage controllers for the STATCOM and ULTC transformer are coordinated and ensure the voltage support. In steady...

  3. Coordinated Voltage Control of a Wind Farm based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2016-01-01

    This paper presents an autonomous wind farm voltage controller based on Model Predictive Control (MPC). The reactive power compensation and voltage regulation devices of the wind farm include Static Var Compensators (SVCs), Static Var Generators (SVGs), Wind Turbine Generators (WTGs) and On......-Load Tap Changing (OLTC) Transformer, and they are coordinated to keep the voltages of all the buses within the feasible range. Moreover, the reactive power distribution is optimized throughout the wind farm in order to maximize the dynamic reactive power reserve. The sensitivity coefficients...... are calculated based on an analytical method to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both voltage violated and normal operation conditions. A wind farm with 20 wind turbines was used to conduct case studies to verify the proposed coordinated...

  4. Autonomous Coil Alignment System Using Fuzzy Steering Control for Electric Vehicles with Dynamic Wireless Charging

    Directory of Open Access Journals (Sweden)

    Karam Hwang

    2015-01-01

    Full Text Available An autonomous coil alignment system (ACAS using fuzzy steering control is proposed for vehicles with dynamic wireless charging. The misalignment between the power receiver coil and power transmitter coil is determined based on the voltage difference between two coils installed on the front-left/front-right of the power receiver coil and is corrected through autonomous steering using fuzzy control. The fuzzy control is chosen over other control methods for implementation in ACAS due to the nonlinear characteristic between voltage difference and lateral misalignment distance, as well as the imprecise and constantly varying voltage readings from sensors. The operational validity and feasibility of the ACAS are verified through simulation, where the vehicle equipped with ACAS is able to align with the power transmitter in the road majority of the time during operation, which also implies achieving better wireless power delivery.

  5. A Half-Bridge Voltage Balancer with New Controller for Bipolar DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    Byung-Moon Han

    2016-03-01

    Full Text Available This paper proposes a half-bridge voltage balancer with a new controller for bipolar DC distribution systems. The proposed control scheme consists of two cascaded Proportional Integral (PI controls rather than one PI control for balancing the pole voltage. In order to confirm the excellence of voltage balancing performance, a typical bipolar DC distribution system including a half-bridge voltage balancer with proposed controller was analyzed by computer simulations. Experiments with a scaled prototype were also carried out to confirm the simulation results. The half-bridge voltage balancer with proposed controller shows better performance than the half-bridge voltage balancer with one PI control for balancing the pole voltage.

  6. Battery charging system

    Energy Technology Data Exchange (ETDEWEB)

    Carollo, J.A.; Kalinsky, W.A.

    1984-02-21

    A battery charger utilizes three basic modes of operation that includes a maintenance mode, a rapid charge mode and time controlled limited charging mode. The device utilizes feedback from the battery being charged of voltage, current and temperature to determine the mode of operation and the time period during which the battery is being charged.

  7. Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

    Directory of Open Access Journals (Sweden)

    Pui-Sun Lei

    2015-01-01

    Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

  8. Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2012-04-01

    Full Text Available AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software.

  9. More stability and robustness with the multi-loop control solution for dynamic voltage restorer (DVR)

    OpenAIRE

    2009-01-01

    This paper presents the application of dynamic voltage restorers (DVR) on power distribution systems for mitigation of voltage sags/swells at critical loads. DVR is one of the compensating types of custom power devices. An adequate modeling and simulation of DVR, including controls in MATLAB, based on forced-commutated voltage source converter (VSC), has been proved suitable for compensating the voltage sags/swells. In this paper, a double loop control method is proposed for the improvement o...

  10. SECONDARY VOLTAGE CONTROL BASED ON ADAPTIVE NEURAL PI CONTROLLERS

    Directory of Open Access Journals (Sweden)

    RUBEN TAPIA

    2010-01-01

    Full Text Available Este trabajo tiene como objetivo presentar el desempeño de un controlador basado en redes neuronales Bspline que regula el aporte de potencia reactiva de las máquinas síncronas. Debido a que los sistemas de potencia operan con parámetros no estacionarios y configuración cambiante, es preferible utilizar esquemas de control adaptativos. La tecnología de control debe asegurar su desempeño en términos de condiciones operativas prácticas de los sistemas de potencia, que considere la diversidad de cargas conectadas a la red y maximice la disponibilidad de recursos. La red neuronal Bspline es una herramienta conveniente para implementar el control adaptativo de voltaje, con la posibilidad de llevar a cabo ésta tarea enlínea considerando las no linealidades del sistema. El despacho de potencia reactiva se basa en la premisa de que cada máquina debe aportar en proporción a su capacidad nominal de operación. La aplicabilidad de la propuesta se demuestra mediante simulación en un sistema de potencia multimáquinas.

  11. Uncoupling charge movement from channel opening in voltage-gated potassium channels by ruthenium complexes.

    Science.gov (United States)

    Jara-Oseguera, Andrés; Ishida, Itzel G; Rangel-Yescas, Gisela E; Espinosa-Jalapa, Noel; Pérez-Guzmán, José A; Elías-Viñas, David; Le Lagadec, Ronan; Rosenbaum, Tamara; Islas, León D

    2011-05-06

    The Kv2.1 channel generates a delayed-rectifier current in neurons and is responsible for modulation of neuronal spike frequency and membrane repolarization in pancreatic β-cells and cardiomyocytes. As with other tetrameric voltage-activated K(+)-channels, it has been proposed that each of the four Kv2.1 voltage-sensing domains activates independently upon depolarization, leading to a final concerted transition that causes channel opening. The mechanism by which voltage-sensor activation is coupled to the gating of the pore is still not understood. Here we show that the carbon-monoxide releasing molecule 2 (CORM-2) is an allosteric inhibitor of the Kv2.1 channel and that its inhibitory properties derive from the CORM-2 ability to largely reduce the voltage dependence of the opening transition, uncoupling voltage-sensor activation from the concerted opening transition. We additionally demonstrate that CORM-2 modulates Shaker K(+)-channels in a similar manner. Our data suggest that the mechanism of inhibition by CORM-2 may be common to voltage-activated channels and that this compound should be a useful tool for understanding the mechanisms of electromechanical coupling.

  12. Controlled Delivery of Vancomycin via Charged Hydrogels.

    Science.gov (United States)

    Gustafson, Carl T; Boakye-Agyeman, Felix; Brinkman, Cassandra L; Reid, Joel M; Patel, Robin; Bajzer, Zeljko; Dadsetan, Mahrokh; Yaszemski, Michael J

    2016-01-01

    Surgical site infection (SSI) remains a significant risk for any clean orthopedic surgical procedure. Complications resulting from an SSI often require a second surgery and lengthen patient recovery time. The efficacy of antimicrobial agents delivered to combat SSI is diminished by systemic toxicity, bacterial resistance, and patient compliance to dosing schedules. We submit that development of localized, controlled release formulations for antimicrobial compounds would improve the effectiveness of prophylactic surgical wound antibiotic treatment while decreasing systemic side effects. Our research group developed and characterized oligo(poly(ethylene glycol)fumarate)/sodium methacrylate (OPF/SMA) charged copolymers as biocompatible hydrogel matrices. Here, we report the engineering of this copolymer for use as an antibiotic delivery vehicle in surgical applications. We demonstrate that these hydrogels can be efficiently loaded with vancomycin (over 500 μg drug per mg hydrogel) and this loading mechanism is both time- and charge-dependent. Vancomycin release kinetics are shown to be dependent on copolymer negative charge. In the first 6 hours, we achieved as low as 33.7% release. In the first 24 hours, under 80% of total loaded drug was released. Further, vancomycin release from this system can be extended past four days. Finally, we show that the antimicrobial activity of released vancomycin is equivalent to stock vancomycin in inhibiting the growth of colonies of a clinically derived strain of methicillin-resistant Staphylococcus aureus. In summary, our work demonstrates that OPF/SMA hydrogels are appropriate candidates to deliver local antibiotic therapy for prophylaxis of surgical site infection.

  13. Controlled Delivery of Vancomycin via Charged Hydrogels.

    Directory of Open Access Journals (Sweden)

    Carl T Gustafson

    Full Text Available Surgical site infection (SSI remains a significant risk for any clean orthopedic surgical procedure. Complications resulting from an SSI often require a second surgery and lengthen patient recovery time. The efficacy of antimicrobial agents delivered to combat SSI is diminished by systemic toxicity, bacterial resistance, and patient compliance to dosing schedules. We submit that development of localized, controlled release formulations for antimicrobial compounds would improve the effectiveness of prophylactic surgical wound antibiotic treatment while decreasing systemic side effects. Our research group developed and characterized oligo(poly(ethylene glycolfumarate/sodium methacrylate (OPF/SMA charged copolymers as biocompatible hydrogel matrices. Here, we report the engineering of this copolymer for use as an antibiotic delivery vehicle in surgical applications. We demonstrate that these hydrogels can be efficiently loaded with vancomycin (over 500 μg drug per mg hydrogel and this loading mechanism is both time- and charge-dependent. Vancomycin release kinetics are shown to be dependent on copolymer negative charge. In the first 6 hours, we achieved as low as 33.7% release. In the first 24 hours, under 80% of total loaded drug was released. Further, vancomycin release from this system can be extended past four days. Finally, we show that the antimicrobial activity of released vancomycin is equivalent to stock vancomycin in inhibiting the growth of colonies of a clinically derived strain of methicillin-resistant Staphylococcus aureus. In summary, our work demonstrates that OPF/SMA hydrogels are appropriate candidates to deliver local antibiotic therapy for prophylaxis of surgical site infection.

  14. Three-Function Logic Gate Controlled by Analog Voltage

    Science.gov (United States)

    Zebulum, Ricardo; Stoica, Adrian

    2006-01-01

    The figure is a schematic diagram of a complementary metal oxide/semiconductor (CMOS) electronic circuit that performs one of three different logic functions, depending on the level of an externally applied control voltage, V(sub sel). Specifically, the circuit acts as A NAND gate at V(sub sel) = 0.0 V, A wire (the output equals one of the inputs) at V(sub sel) = 1.0 V, or An AND gate at V(sub sel) = -1.8 V. [The nominal power-supply potential (VDD) and logic "1" potential of this circuit is 1.8 V.] Like other multifunctional circuits described in several prior NASA Tech Briefs articles, this circuit was synthesized following an automated evolutionary approach that is so named because it is modeled partly after the repetitive trial-and-error process of biological evolution. An evolved circuit can be tested by computational simulation and/or tested in real hardware, and the results of the test can provide guidance for refining the design through further iteration. The evolutionary synthesis of electronic circuits can now be implemented by means of a software package Genetic Algorithms for Circuit Synthesis (GACS) that was developed specifically for this purpose. GACS was used to synthesize the present trifunctional circuit. As in the cases of other multifunctional circuits described in several prior NASA Tech Briefs articles, the multiple functionality of this circuit, the use of a single control voltage to select the function, and the automated evolutionary approach to synthesis all contribute synergistically to a combination of features that are potentially advantageous for the further development of robust, multiple-function logic circuits, including, especially, field-programmable gate arrays (FPGAs). These advantages include the following: This circuit contains only 9 transistors about half the number of transistors that would be needed to obtain equivalent NAND/wire/AND functionality by use of components from a standard digital design library. If

  15. Analytical model of threshold voltage degradation due to localized charges in gate material engineered Schottky barrier cylindrical GAA MOSFETs

    Science.gov (United States)

    Kumar, Manoj; Haldar, Subhasis; Gupta, Mridula; Gupta, R. S.

    2016-10-01

    The threshold voltage degradation due to the hot carrier induced localized charges (LC) is a major reliability concern for nanoscale Schottky barrier (SB) cylindrical gate all around (GAA) metal-oxide-semiconductor field-effect transistors (MOSFETs). The degradation physics of gate material engineered (GME)-SB-GAA MOSFETs due to LC is still unexplored. An explicit threshold voltage degradation model for GME-SB-GAA-MOSFETs with the incorporation of localized charges (N it) is developed. To accurately model the threshold voltage the minimum channel carrier density has been taken into account. The model renders how +/- LC affects the device subthreshold performance. One-dimensional (1D) Poisson’s and 2D Laplace equations have been solved for two different regions (fresh and damaged) with two different gate metal work-functions. LCs are considered at the drain side with low gate metal work-function as N it is more vulnerable towards the drain. For the reduction of carrier mobility degradation, a lightly doped channel has been considered. The proposed model also includes the effect of barrier height lowering at the metal-semiconductor interface. The developed model results have been verified using numerical simulation data obtained by the ATLAS-3D device simulator and excellent agreement is observed between analytical and simulation results.

  16. A Versatile Control Scheme For Dynamic Voltage Restorer To Limit Downstream Fault Currents

    Directory of Open Access Journals (Sweden)

    A.Nagendra

    2014-12-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a custom power device utilized to counteract voltage sags. It injects controlled three-phase ac voltages in series with the supply voltage, subsequent to voltage sag, to enhance voltage quality by adjusting the voltage magnitude, wave shape, and phase angle. The DVR is conventionally bypassed during a downstream fault to prevent potential adverse impacts on the fault and to protect the DVR components against the fault current. This paper proposes an augmented control strategy for the DVR that provides:1 voltage-sag compensation under balanced and unbalanced conditions and 2 a fault current interruption (FCI function. This paper introduces and evaluates an auxiliary control strategy for downstream fault current interruption in a radial distribution line by means of a dynamic voltage restorer (DVR. The proposed controller supplements the voltage-sag compensation control of the DVR. It does not require phaselocked loop and independently controls the magnitude and phase angle of the injected voltage for each phase. Fast least error squares digital filters are used to estimate the magnitude and phase of the measured voltages and effectively reduce the impacts of noise, harmonics, and disturbances on the estimated phasor parameters, and this enables effective fault current interrupting even under arcing fault conditions. The performance of the DVR for fault current interruption is analyzed by using MATLAB/SIMULINK software.

  17. Correction factor based double model fuzzy logic control strategy of arc voltage in pulsed MIG welding

    Institute of Scientific and Technical Information of China (English)

    Wu Kaiyuan; Huang Shisheng; Meng Yongmin

    2005-01-01

    According to the feature of arc voltage control in welding steel using pulsed MIG welding, a correction factor based double model fuzzy logic controller (FLC) was developed to realize the arc voltage control by means of arc voltage feedback.When the error of peak arc voltage was great, a coarse adjusting fuzzy logic control rules with correction factor was designed,in the controller, the peak arc voltage was controlled by the wire feeding speed by means of arc voltage feedback. When the error of peak arc voltage was small, a fine adjusting fuzzy logic control rules with correction factor was designed, in this controller, the peak arc voltage was controlled by the background time by means of arc voltage feedback. The FLC was realized in a Look-Up Table ( LUT) method. Experiments had been carried out aiming at implementing the control strategy to control the arc length change in welding process. Experimental results show that the controller proposed enables the consistency of arc length and the stabolity of arc voltage and welding process to be achieved in pulsed MIG welding process.

  18. Application of Load Compensation in Voltage Controllers of Large Generators in the Polish Power Grid

    Directory of Open Access Journals (Sweden)

    Bogdan Sobczak

    2014-03-01

    Full Text Available The Automatic Voltage Regulator normally controls the generator stator terminal voltage. Load compensation is used to control the voltage which is representative of the voltage at a point either within or external to the generator. In the Polish Power Grid (PPG compensation is ready to use in every AVR of a large generator, but it is utilized only in the case of generators operating at the same medium voltage buses. It is similar as in most European Power Grids. The compensator regulating the voltage at a point beyond the machine terminals has significant advantages in comparison to the slower secondary Voltage and Reactive Power Control System (ARNE1. The compensation stiffens the EHV grid, which leads to improved voltage quality in the distribution grid. This effect may be particularly important in the context of the dynamic development of wind and solar energy.

  19. Comparison of Twitch Responses During Current- or Voltage-Controlled Transcutaneous Neuromuscular Electrical Stimulation.

    Science.gov (United States)

    Vargas Luna, José Luis; Krenn, Matthias; Löfler, Stefan; Kern, Helmut; Cortés R, Jorge A; Mayr, Winfried

    2015-10-01

    Neuromuscular electrical stimulation (NMES) is an established method for functional restoration of muscle function, rehabilitation, and diagnostics. In this work, NMES was applied with surface electrodes placed on the anterior thigh to identify the main differences between current-controlled (CC) and voltage-controlled (VC) modes. Measurements of the evoked knee extension force and the myoelectric signal of quadriceps and hamstrings were taken during stimulation with different amplitudes, pulse widths, and stimulation techniques. The stimulation pulses were rectangular and symmetric biphasic for both stimulation modes. The electrode-tissue impedance influences the differences between CC and VC stimulation. The main difference is that for CC stimulation, variation of pulse width and amplitude influences the amount of nerve depolarization, whereas VC stimulation is only dependent on amplitude variations for pulse widths longer than 150 μs. An important remark is that these findings are strongly dependent on the characteristics of the electrode-skin interface. In our case, we used large stimulation electrodes placed on the anterior thigh, which cause higher capacitive effects. The controllability, voltage compliance, and charge characteristics of each stimulation technique should be considered during the stimulators design. For applications that require the activation of a large amount of nerve fibers, VC is a more suitable option. In contrast, if the application requires a high controllability, then CC should be chosen prior to VC.

  20. Charge and Strain Control of Interface Magnetism

    Science.gov (United States)

    Fitzsimmons, M. R.; Dumesnil, K.; Jaouen, N.; Maroutian, T.; Agnus, G.; Tonnerre, J.-M.; Kirby, B.; Fohtung, E.; Holladay, B.; Fullerton, E. E.; Shpyrko, O.; Sinha, S. K.; Wang, Q.; Chen, A.; Jia, Q. X.

    2015-03-01

    We studied the influence of an electric field applied to an La0.67Sr0.33MnO3 (LSMO) layer in a LSMO/Pb(Zr0.2Ti0.8) O3 (PZT)/Nb-doped SrTiO3 (STO) heterostructure by measuring its magnetization depth profile using resonant x-ray magnetic reflectivity. The saturation magnetization of the ferromagnetically-ordered LSMO was not affected by the direction of the polarization of the PZT. However, the ferromagnetic thickness and magnetization of the LSMO film at remanence were reduced for hole-charge accumulation at the LSMO/PZT interface. To understand the independent roles of strain and hole-doping, we performed neutron scattering experiments of La0.8Sr0.2MnO3 films grown on Nb-doped STO in which bending strain (via 4-point bending jig) or electric field (via parallel plate capacitor) was applied to the films. We observed that bending strain affects the saturation magnetization of the LSMO film, whereas electric field affects the remanent magnetization of the film. These observations suggest strain may be a more effective means to control magnetism than charge. This work has benefited from use of CINT(LANL), NIST Center for Neutron Research and the Synchrotron SOLEIL and funding from LANL/LDRD program, DOE-BES (UCSD) and DOD (NMSU).

  1. Hierarchical Control for Voltage Harmonics Compensation in Multi-Area Microgrids

    DEFF Research Database (Denmark)

    Hashempour, Mohammad M.; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez

    2015-01-01

    is proposed. Hierarchical control is applied to control DGs inverters and APFs in a coordinated way. Primary control consists of power droop controller of DGs, selective virtual impedance and voltage/current regulators. Based on the secondary control, voltage compensation of Points of Common Coupling (PCCs......) of multi-area microgrid is carried out by DGs. Voltage compensation of PCCs by DGs may cause violation from maximum allowable voltage distortion at DGs terminals. Thus, tertiary control is used to mitigate these violations by using APF in proper coordination with secondary control. Evaluation...

  2. An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... control strategy is analyzed through small signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  3. An estimator-based distributed voltage-predictive control strategy for AC islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage-predictive control strategy for ac islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage-predictive controller for each...... control strategy is analyzed through small-signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation, and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  4. Voltage-Controlled Sapphire Oscillator: Design, Development, and Preliminary Performance

    Science.gov (United States)

    Wang, R. T.; Dick, G. J.; Tjoelker, R. L.

    2007-08-01

    We present the design for a new short-term frequency standard, the voltage-controlled sapphire oscillator, as a practical and lower-cost alternative to a cryogenic sapphire oscillator operating at liquid helium temperatures. Performance goals are a frequency stability of 1 x 10^-14 (1 second equal to or less than tau equal to or less than 100 seconds), more than 2 years of continuous operation, and practical operability. Key elements include the sapphire resonator, low-power and long-life cryocooler, frequency compensation method, and cryo-Pound design. We report the design verification, experimental results, and test results of the cryocooler environmental sensitivity, as well as a preliminary stability measurement.

  5. More stability and robustness with the multi-loop control solution for dynamic voltage restorer (DVR

    Directory of Open Access Journals (Sweden)

    Abdelkhalek Othmane

    2009-01-01

    Full Text Available This paper presents the application of dynamic voltage restorers (DVR on power distribution systems for mitigation of voltage sags/swells at critical loads. DVR is one of the compensating types of custom power devices. An adequate modeling and simulation of DVR, including controls in MATLAB, based on forced-commutated voltage source converter (VSC, has been proved suitable for compensating the voltage sags/swells. In this paper, a double loop control method is proposed for the improvement of the stability of DVR during the load current variation. For the main loop (Outer Voltage Loop, we use a PI controller for the regulation of the filter condenser voltage. The second loop (Inner Current Loop also uses a PI controller to control the disturbances current during load variation. Simulation results are presented to illustrate and understand the performances of DVR in the compensation of voltage sags/swell even with variation load condition.

  6. Adaptive PI controller to voltage regulation in power systems: STATCOM as a case study.

    Science.gov (United States)

    Tavana, Mohammad Reza; Khooban, Mohammad-Hassan; Niknam, Taher

    2017-01-01

    Static synchronous compensator (STATCOM) provides the means to improve quality and reliability of a power system as it has the functional capability to handle dynamic disturbances, such as transient stability and power oscillation damping as well as to providing voltage regulation. In this paper, a robust adaptive PI-based optimal fuzzy control strategy is proposed to control a STATCOM used in distribution systems. The proposed intelligent strategy is based on a combination of a new General Type-II Fuzzy Logic (GT2FL) with a simple heuristic algorithm named Teaching Learning Based Optimization (TLBO) Algorithm. The proposed framework optimally tunes parameters of a Proportional-Integral (PI) controller which, similar to most of other researchers regarding control of STATCOM, are in charge of controlling the device. The proposed controller guaranties robustness and stability against uncertainties caused by external disturbances or ever-changing nature of the power systems. The TLBO optimizes the parameters of the controller as well as the input and output membership functions. To validate the efficiency of the proposed controller, the obtained simulation results are compared with those of the two most recent researches applied in this field, namely, conventional Proportional Integral (PI) controller and Optimal Fuzzy PI (OFPI) controller. Results demonstrate the successfulness and effectiveness of the proposed online-TLBO General Type-2 Fuzzy PI (OGT2FPI) controller and its superiority over conventional approaches.

  7. Coordinated Voltage Control Scheme for SEIG-Based Wind Park Utilizing Substation STATCOM and ULTC Transformer

    DEFF Research Database (Denmark)

    S. El Moursi, Mohamed; Bak-Jensen, Birgitte; Abdel-Rahman, Mansour Hassan

    2011-01-01

    and optimal tracking secondary voltage control for wind parks based on self-excited induction generators which comprise STATCOM and under-load tap changer (ULTC) substation transformers. The voltage controllers for the STATCOM and ULTC transformer are coordinated and ensure the voltage support. In steady......-state operation, the voltage is controlled by only stepping the tap changer when the voltage is outside the deadband region of the ULTC to minimize the number of taps changes. Thus, the STATCOM will be unloaded and ready to react with higher reactive power margin during contingencies. In the paper, the effects...

  8. Planning Future Electric Vehicle Central Charging Stations Connected to Low-Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Marra, Francesco; Træholt, Chresten; Larsen, Esben

    2012-01-01

    A great interest is recently paid to Electric Vehicles (EV) and their integration into electricity grids. EV can potentially play an important role in power system operation, however, the EV charging infrastructures have been only partly defined, considering them as limited to individual charging...

  9. Enhanced charge efficiency and reduced energy use in capacitive deionization by increasing the discharge voltage

    NARCIS (Netherlands)

    Kim, T.; Dykstra, J.E.; Porada, S.; Wal, van der A.; Yoon, J.; Biesheuvel, P.M.

    2015-01-01

    Capacitive deionization (CDI) is an electrochemical method for water desalination using porous carbon electrodes. A key parameter in CDI is the charge efficiency, ¿, which is the ratio of salt adsorption over charge in a CDI-cycle. Values for ¿ in CDI are typically around 0.5-0.8, significantly less

  10. Enhanced charge efficiency and reduced energy use in capacitive deionization by increasing the discharge voltage

    NARCIS (Netherlands)

    Kim, T.; Dykstra, J.E.; Porada, S.; Wal, van der A.; Yoon, J.; Biesheuvel, P.M.

    2015-01-01

    Capacitive deionization (CDI) is an electrochemical method for water desalination using porous carbon electrodes. A key parameter in CDI is the charge efficiency, ¿, which is the ratio of salt adsorption over charge in a CDI-cycle. Values for ¿ in CDI are typically around 0.5-0.8, significantly less

  11. Game-theoretic control of PHEV charging with power flow analysis

    Directory of Open Access Journals (Sweden)

    Yuan Liu

    2016-03-01

    Full Text Available Due to an ever-increasing market penetration of plug-in hybrid electric vehicles (PHEVs, the charging demand is expected to become a main determinant of the load in future distribution systems. In this paper, we investigate the problem of controlling in-home charging of PHEVs to accomplish peak load shifting while maximizing the revenue of the distribution service provider (DSP and PHEV owners. A leader-follower game model is proposed to characterize the preference and revenue expectation of PHEV owners and DSP, respectively. The follower (PHEV owner decides when to start charging based on the pricing schedule provided by the leader (DSP. The DSP can incentivize the charging of PHEV owners to avoid system peak load. The costs associated with power distribution, line loss, and voltage regulation are incorporated in the game model via power flow analysis. Based on a linear approximation of the power flow equations, the solution of sub-game perfect Nash equilibrium (SPNE is obtained. A case study is performed based on the IEEE 13-bus test feeder and realistic PHEV charging statistics, and the results demonstrate that our proposed PHEV charging control scheme can significantly improve the power quality in distribution systems by reducing the peak load and voltage fluctuations.

  12. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    Science.gov (United States)

    Tex, David M.; Ihara, Toshiyuki; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  13. Control of microbial fuel cell voltage using a gain scheduling control strategy

    Science.gov (United States)

    Boghani, Hitesh C.; Michie, Iain; Dinsdale, Richard M.; Guwy, Alan J.; Premier, Giuliano C.

    2016-08-01

    Recent microbial fuel cell (MFC) research frequently addresses matters associated with scale and deployability. Modularisation is often needed to reduce ohmic losses with increasing volume. Series/parallel is then often an obvious strategy to enhance power quality during operation, to make best use of generated electricity. Hence, voltage reversal resulting from power and voltage mismatch between cells become virtually unavoidable. Control MFC voltages could be used to stabilise MFC stacks. Here, nonlinear MFCs are controlled using simple gain scheduled Proportional + Integral actions. Parsimonious control may be necessary for implementation in MFC arrays, so minimising costs. Controller parameterisation used several linearised models over the dynamic operating range of the MFCs. Controller gains were then scheduled according to the operating conditions. A digital potentiometer was used to actuate the control, varying the current sourced from the MFC. The results show that the controller was able to control MFC voltages, rejecting the disturbances. It was shown that the controller was transferable between MFCs with different power performances. This study demonstrates that the control of MFCs can be achieved with relatively simple digital approaches, plausibly implementable using low cost microcontrollers, and likely to be useful in the effective deployment of MFCs in large scale arrays.

  14. Flexible voltage support control for three-phase distributed generation inverters under grid fault

    DEFF Research Database (Denmark)

    Camacho, Antonio; Castilla, Miguel; Miret, Jaume

    2013-01-01

    Operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three phase grid......Ancillary services for distributed generation systems become a challenging issue to smartly integrate renewable energy sources into the grid. Voltage control is one of these ancillary services which can ride through and support the voltage under grid faults. Grid codes from the Transmission System...... connected inverters is proposed. In three phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one or two phase faults, the main concern of the distributed generation inverter is to equalize voltages by reducing the negative symmetric...

  15. Distributed voltage control coordination between renewable generation plants in MV distribution grids

    DEFF Research Database (Denmark)

    Petersen, Lennart; Iov, Florin

    2017-01-01

    This study focuses on distributed voltage control coordination between renewable generation plants in medium-voltage distribution grids (DGs). A distributed offline coordination concept has been defined in a previous publication, leading to satisfactory voltage regulation in the DG. However, here...

  16. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    OpenAIRE

    Feri Yusivar; M. Shanizal; A. Subiantoro; Gunawan, R

    2014-01-01

    Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM) with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likel...

  17. 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

    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...

  18. Voltage-controlled magnetic anisotropy in Fe|MgO tunnel junctions studied by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, Shinji, E-mail: miwa@mp.es.osaka-u.ac.jp; Matsuda, Kensho; Tanaka, Kazuhito; Goto, Minori; Suzuki, Yoshishige [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kotani, Yoshinori; Nakamura, Tetsuya [Japan Synchrotron Radiation Research Institute/SPring-8, Sayo, Hyogo 679-5198 (Japan)

    2015-10-19

    In this study, voltage-controlled magnetic anisotropy (VCMA) in Fe|MgO tunnel junctions was investigated via the magneto-optical Kerr effect, soft x-ray absorption spectroscopy, and magnetic circular dichroism spectroscopy. The Fe|MgO tunnel junctions showed enhanced perpendicular magnetic anisotropy under external negative voltage, which induced charge depletion at the Fe|MgO interface. Despite the application of voltages of opposite polarity, no trace of chemical reaction such as a redox reaction attributed to O{sup 2−} migration was detected in the x-ray absorption spectra of the Fe. The VCMA reported in the Fe|MgO-based magnetic tunnel junctions must therefore originate from phenomena associated with the purely electric effect, that is, surface electron doping and/or redistribution induced by an external electric field.

  19. Optimization of Bi-Directional Flyback Converter for a High Voltage Capacitor Charging Application

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

    2014-01-01

    a 24 V battery. The proposed optimization routine sweeps through a database of low voltage switching devices, and transformer core types and sizes. For each core, important winding parameters such as, the vertical winding space allocation for primary and secondary windings, and the spacing between...

  20. Cross Voltage Control with Inner Hysteresis Current Control for Multi-output Boost Converter

    DEFF Research Database (Denmark)

    Nami, Alireza; Zare, Firuz; Blaabjerg, Frede

    2009-01-01

    with inner hysteresis current control loop has been proposed to keep the simplicity of the control law for the double-output MOB converter, which can be implemented by a combination of analogue and logical ICs or simple microcontroller to constrain the output voltages of MOB converter at their reference...

  1. Cross Voltage Control with Inner Hysteresis Current Control for Multi-output Boost Converter

    DEFF Research Database (Denmark)

    Nami, Alireza; Zare, Firuz; Blaabjerg, Frede

    2009-01-01

    with inner hysteresis current control loop has been proposed to keep the simplicity of the control law for the double-output MOB converter, which can be implemented by a combination of analogue and logical ICs or simple microcontroller to constrain the output voltages of MOB converter at their reference...

  2. Power flow control and voltage stability limit: regulating transformer versus UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Haque, M.H. [Nanyang Technological Univ., Center for Advanced Power Electronics, Nanyang (Singapore)

    2004-05-01

    Power flow through an AC transmission line can be controlled by injecting an adjustable compensating voltage in series with the line. This paper evaluates and compares the power flow control ranges of a simple system obtained by injecting an adjustable series compensating voltage produced by a regulating transformer and unified power flow controller. The static voltage stability limits of the system with a regulating transformer and unified power flow controller are also determined and compared. In evaluating the power flow control ranges and voltage stability limits, the transmission line of the system is modelled in four different ways. The results obtained for various line models are also compared. (Author)

  3. 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

    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......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...

  4. An interleaved five-level boost converter with voltage-balance control

    DEFF Research Database (Denmark)

    Chen, Jianfei; Hou, Shiying; Deng, Fujin

    2016-01-01

    This paper proposes an interleaved five-level boost converter based on switched-capacitor network. Operating principle of the converter under CCM mode is analyzed. High voltage gain, low component stress, small input current ripple, and self-balance function for capacitor voltages in the switched......-capacitor networks are achieved. Besides, a three-loop control strategy including outer voltage loop, inner current loop and voltage-balance loop has been researched to achieve good performances and voltage-balance effect. Experimental study has been done to verify the correctness and feasibility of the proposed...... converter and control strategy....

  5. Distributed Control to Ensure Proportional Load Sharing and Improve Voltage Regulation in Low-Voltage DC Microgrids

    DEFF Research Database (Denmark)

    Anand, Sandeep; G. Fernandes, Baylon; Guerrero, Josep M.

    2013-01-01

    DC microgrids are gaining popularity due to high efficiency, high reliability, and easy interconnection of renewable sources as compared to the ac system. Control objectives of dc microgrid are: 1) to ensure equal load sharing (in per unit) among sources; and 2) to maintain low-voltage regulation...

  6. Low voltage fault ride through control in MMC-HVDC

    DEFF Research Database (Denmark)

    Chaudhary, S.; Teodorescu, R.; Rizadis, D.

    2017-01-01

    Modular multilevel converters (MMCs) are the latest converter topology for the high voltage high power applications like the high voltage dc (HVDC) transmission. This paper presents the response of an MMC-HVDC converter during grid faults. Recent grid code requirements specify reactive current...

  7. A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM

    Directory of Open Access Journals (Sweden)

    Yao Xiaolong

    2015-01-01

    Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.

  8. Voltage Controller Saves Energy, Prolongs Life of Motors

    Science.gov (United States)

    2007-01-01

    In 1985, Power Efficiency Corporation of Las Vegas licensed NASA voltage controller technology from Marshall Space Flight Center. In the following years, Power Efficiency made patented improvements to the technology and marketed the resulting products throughout the world as the Performance Controller and the Power Efficiency energy-saving soft start. Soft start gradually introduces power to an electric motor, thus eliminating the harsh, violent mechanical stresses of having the device go from a dormant state to one of full activity; prevents it from running too hot; and increases the motor's lifetime. The product can pay for itself through the reduction in electricity consumed (according to Power Efficiency, within 3 years), depending on the duty cycle of the motor and the prevailing power rates. In many instances, the purchaser is eligible for special utility rebates for the environmental protection it provides. Common applications of Power Efficiency's soft start include mixers, grinders, granulators, conveyors, crushers, stamping presses, injection molders, elevators with MG sets, and escalators. The device has been retrofitted onto equipment at major department store chains, hotels, airports, universities, and for various manufacturers

  9. Compensation of negative sequence stator flux of doubly-fed induction generator using polar voltage control-based direct torque control under unbalanced grid voltage condition

    Directory of Open Access Journals (Sweden)

    Badrinarayan Bansilal Pimple

    2015-02-01

    Full Text Available This study proposes a polar voltage control-based direct torque control method to reduce the effects of unbalanced grid voltage on doubly-fed induction generator (DFIG-based wind turbine system. Under unbalanced grid voltage, the stator flux has a negative sequence component which leads to second harmonic pulsation in torque, stator active power, stator reactive power, stator current and rotor current. In the control scheme, the negative sequence rotor voltage vector is controlled to compensate the negative sequence stator flux by negative sequence rotor flux. Simulation study is carried out on a 2 MW DFIG system using MATLAB/SIMULINK. Feasibility of the proposed control strategy is experimentally verified on a 1.5 kW DFIG system.

  10. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Science.gov (United States)

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  11. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Directory of Open Access Journals (Sweden)

    Fadi M Albatsh

    Full Text Available This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs including the line stability index (LQP, the voltage collapse proximity indicator (VCPI, and the line stability index (Lmn are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO and differential evolution (DE, which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  12. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    Science.gov (United States)

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  13. 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.

  14. A Practical Fast Acting Control Scheme For Fuzzy Logic-Based Voltage Stabilization Control

    Directory of Open Access Journals (Sweden)

    E. E. EL-Kholy

    2005-03-01

    Full Text Available This paper presents a simplified control model for stabilizing a load voltage using a switched reactor in parallel with a fixed capacitor of static VAR compensator. Two IGBT’s are used to control the reactance of the switched reactor. A uniform pulse width modulation is used for controlling the two switches. The compensator has a simple control circuit and structure. A complete modeling and numerical simulation for the proposed systems is presented. A high speed Digital Signal Processor is used for implementing proportional-integral (PI and fuzzy load voltage controllers. Experimental results indicate the superiority of fuzzy logic control over the conventional proportional-integral control method. Simulation results are reported and proved to be in good agreement with the relevant experimental results.

  15. Comparison of two voltage control strategies for a wind power plant

    DEFF Research Database (Denmark)

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

    2011-01-01

    , it is possible to investigate the influence of the plant control gain, short circuit ratio, and time delays on the system stability, as well as the fulfillment of the design requirements. The implemented plant voltage control is based on a slope voltage controller, which calculates the references to be sent...... to the wind turbines, according to the slope gain and the difference between the reference and measured voltage at the point of connection. The results show that for a system where the time delay between the central control and the actuators is not negligible, the performance of a decentralized voltage...

  16. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Energy Technology Data Exchange (ETDEWEB)

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman

    2011-04-01

    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  17. On-line equalization for lithium-ion battery packs based on charging cell voltages: Part 1. Equalization based on remaining charging capacity estimation

    Science.gov (United States)

    Zheng, Yuejiu; Ouyang, Minggao; Lu, Languang; Li, Jianqiu; Han, Xuebing; Xu, Liangfei

    2014-02-01

    Because of the inevitable inconsistency during manufacture and use of battery cells, cell variations in battery packs have significant impacts on battery pack capacities, durability and safety for electric vehicles (EVs). To reduce cell variations and increase pack capacity, cell equalization is essentially required. In the series of two papers, we discover that dissipative cell equalization (DCE) using dissipative resistances is a feasible on-line equalization method for battery packs in EVs. We subsequently propose on-line equalization algorithms for lithium-ion battery packs based on charging cell voltage curves (CCVCs). The objective of these algorithms is to maximize pack capacities by conditioning CCVCs. As the first paper of the series, we first briefly review equalization topologies and algorithms. We discover cell remaining charging capacity (RCC) can be on-line estimated and further propose DCE algorithm based on remaining charging capacity estimation (RCCE). We establish a pack model with 8 cells in series and simulate 4 scenes with different cell variations. RCCE-DCE algorithm is proved to be effective by comparing pack capacities with/without RCCE-DCE algorithm. The equalization capability and over-equalization prevention are further examined, and the result shows that RCCE-DCE algorithm is suitable for on-line equalization in EVs.

  18. The efficiency of nanotube formation on titanium anodized under voltage and current control in fluoride/glycerol electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Valota, A; LeClere, D J; Hashimoto, T; Skeldon, P; Thompson, G E [Corrosion and Protection Centre, School of Materials, The University of Manchester, PO Box 88, Manchester M60 1QD (United Kingdom); Berger, S; Kunze, J; Schmuki, P [Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Martenstrasse 7, D-91058 Erlangen (Germany)

    2008-09-03

    The formation of nanotubes on titanium is compared for anodizing under controlled voltage and controlled current in a fluoride/glycerol electrolyte. Rutherford backscattering spectroscopy and nuclear reaction analysis are employed to determine the film compositions. Film morphologies are examined by electron microscopy. The findings reveal films of approximate composition TiO{sub 2}.0.15TiF{sub 4} that probably also contain derivatives of glycerol. Controlled voltage conditions resulted in more uniform final nanotube dimensions, for a particular charge density, and the highest efficiency of film growth, with the charge of the titanium in the film representing {approx}48% of the charge passed during anodizing. Under current control, the efficiency decreased from {approx}40% to {approx}23% with increase of the current density from 0.1 to 0.5 mA cm{sup -2}. Further, the thickness of the barrier layer was sometimes enhanced under current control, possibly due to a non-uniform current distribution and consequently elevated local temperature.

  19. System dynamic model and charging control of lead-acid battery for stand-alone solar PV system

    KAUST Repository

    Huang, B.J.

    2010-05-01

    The lead-acid battery which is widely used in stand-alone solar system is easily damaged by a poor charging control which causes overcharging. The battery charging control is thus usually designed to stop charging after the overcharge point. This will reduce the storage energy capacity and reduce the service time in electricity supply. The design of charging control system however requires a good understanding of the system dynamic behaviour of the battery first. In the present study, a first-order system dynamics model of lead-acid battery at different operating points near the overcharge voltage was derived experimentally, from which a charging control system based on PI algorithm was developed using PWM charging technique. The feedback control system for battery charging after the overcharge point (14 V) was designed to compromise between the set-point response and the disturbance rejection. The experimental results show that the control system can suppress the battery voltage overshoot within 0.1 V when the solar irradiation is suddenly changed from 337 to 843 W/m2. A long-term outdoor test for a solar LED lighting system shows that the battery voltage never exceeded 14.1 V for the set point 14 V and the control system can prevent the battery from overcharging. The test result also indicates that the control system is able to increase the charged energy by 78%, as compared to the case that the charging stops after the overcharge point (14 V). © 2010 Elsevier Ltd. All rights reserved.

  20. Coordinated Voltage Control in Offshore HVDC Connected Cluster of Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Rather, Zakir Hussain; Rimez, Johan;

    2016-01-01

    This paper presents a coordinated voltage control scheme (CVCS) for a cluster of offshore wind power plants (OWPPs) connected to a VSC HVDC system. The primary control point of the proposed voltage control scheme is the introduced Pilot bus, which is having the highest short circuit capacity...

  1. High Bandwidth Zero Voltage Injection Method for Sensorless Control of PMSM

    DEFF Research Database (Denmark)

    Ge, Xie; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2014-01-01

    High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses to be inj...... in a fast current regulation performance. Injection of zero voltage also minimizes the inverter voltage error effects caused by the dead-time.......High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses...... to be injected before the position may be estimated. In this paper, a single pulse zero voltage injection method is proposed. The rotor position is directly estimated from the current ripple at half of the switching frequency. No machine parameters are needed and using of filters is avoided. This results...

  2. Voltage Controlled Magnetic Skyrmion Motion for Racetrack Memory.

    Science.gov (United States)

    Kang, Wang; Huang, Yangqi; Zheng, Chentian; Lv, Weifeng; Lei, Na; Zhang, Youguang; Zhang, Xichao; Zhou, Yan; Zhao, Weisheng

    2016-03-15

    Magnetic skyrmion, vortex-like swirling topologically stable spin configurations, is appealing as information carrier for future nanoelectronics, owing to the stability, small size and extremely low driving current density. One of the most promising applications of skyrmion is to build racetrack memory (RM). Compared to domain wall-based RM (DW-RM), skyrmion-based RM (Sky-RM) possesses quite a few benefits in terms of energy, density and speed etc. Until now, the fundamental behaviors, including nucleation/annihilation, motion and detection of skyrmion have been intensively investigated. However, one indispensable function, i.e., pinning/depinning of skyrmion still remains an open question and has to be addressed before applying skyrmion for RM. Furthermore, Current research mainly focuses on physical investigations, whereas the electrical design and evaluation are still lacking. In this work, we aim to promote the development of Sky-RM from fundamental physics to realistic electronics. First, we investigate the pinning/depinning characteristics of skyrmion in a nanotrack with the voltage-controlled magnetic anisotropy (VCMA) effect. Then, we propose a compact model and design framework of Sky-RM for electrical evaluation. This work completes the elementary memory functionality of Sky-RM and fills the technical gap between the physicists and electronic engineers, making a significant step forward for the development of Sky-RM.

  3. Apparatus for Controlling Low Power Voltages in Space Based Processing Systems

    Science.gov (United States)

    Petrick, David J. (Inventor)

    2017-01-01

    A low power voltage control circuit for use in space missions includes a switching device coupled between an input voltage and an output voltage. The switching device includes a control input coupled to an enable signal, wherein the control input is configured to selectively turn the output voltage on or off based at least in part on the enable signal. A current monitoring circuit is coupled to the output voltage and configured to produce a trip signal, wherein the trip signal is active when a load current flowing through the switching device is determined to exceed a predetermined threshold and is inactive otherwise. The power voltage control circuit is constructed of space qualified components.

  4. Time varying voltage combustion control and diagnostics sensor

    Science.gov (United States)

    Chorpening, Benjamin T.; Thornton, Jimmy D.; Huckaby, E. David; Fincham, William

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  5. Methods, systems and apparatus for controlling third harmonic voltage when operating a multi-space machine in an overmodulation region

    Energy Technology Data Exchange (ETDEWEB)

    Perisic, Milun; Kinoshita, Michael H; Ranson, Ray M; Gallegos-Lopez, Gabriel

    2014-06-03

    Methods, system and apparatus are provided for controlling third harmonic voltages when operating a multi-phase machine in an overmodulation region. The multi-phase machine can be, for example, a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided. For example, when the reference voltage vector is determined to be within the overmodulation region, an angle of the reference voltage vector can be modified to generate a reference voltage overmodulation control angle, and a magnitude of the reference voltage vector can be modified, based on the reference voltage overmodulation control angle, to generate a modified magnitude of the reference voltage vector. By modifying the reference voltage vector, voltage command signals that control a five-phase inverter module can be optimized to increase output voltages generated by the five-phase inverter module.

  6. Epoxy Based Nanodielectrics for High Voltage DC Applications: Synthesis, Dielectric Properties and Space Charge Dynamics

    NARCIS (Netherlands)

    Andritsch, T.M.

    2010-01-01

    Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC

  7. Epoxy Based Nanodielectrics for High Voltage DC Applications: Synthesis, Dielectric Properties and Space Charge Dynamics

    NARCIS (Netherlands)

    Andritsch, T.M.

    2010-01-01

    Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC applicat

  8. Highly tunable local gate controlled complementary graphene device performing as inverter and voltage controlled resistor.

    Science.gov (United States)

    Kim, Wonjae; Riikonen, Juha; Li, Changfeng; Chen, Ya; Lipsanen, Harri

    2013-10-04

    Using single-layer CVD graphene, a complementary field effect transistor (FET) device is fabricated on the top of separated back-gates. The local back-gate control of the transistors, which operate with low bias at room temperature, enables highly tunable device characteristics due to separate control over electrostatic doping of the channels. Local back-gating allows control of the doping level independently of the supply voltage, which enables device operation with very low VDD. Controllable characteristics also allow the compensation of variation in the unintentional doping typically observed in CVD graphene. Moreover, both p-n and n-p configurations of FETs can be achieved by electrostatic doping using the local back-gate. Therefore, the device operation can also be switched from inverter to voltage controlled resistor, opening new possibilities in using graphene in logic circuitry.

  9. Lateral Current Reduction by Voltage Drop Compensator for Multiple Autonomously Controlled UPS Connected in Parallel

    Science.gov (United States)

    Sato, Eduardo Kazuhide; Kawamura, Atsuo

    An autonomous control for redundant parallelism of uninterruptible power supplies (UPS) connected in parallel has successfully been proposed and discussed in theoretical and experimental terms. This independent control only requires the measurement of the output current. With the computation of the active and reactive currents, proportional-integral-based controllers provide the phase angle and amplitude, respectively, of the output voltage. However, when voltage difference between UPS exists, there is a flow of reactive lateral current, which makes the load sharing disproportional. A preliminary approach to reduce this circulating current considers a high proportional gain in the control equation for output voltage amplitude in order to reduce the offset error. Nevertheless it implies in high variation of the voltage amplitude, so that voltage levels easily reaches the limit, and the respective control equation becomes incapable to compensate any voltage difference. This paper proposes a compensator to counterbalance the voltage drop caused by the proportional gain of the control equation for the voltage amplitude. Implementation in an experimental setup with three UPS with different output rating connected in parallel shows significant reduction of the reactive lateral current, and consequent improvement of the current distribution, including employment of voltage limiters (1%), under various conditions.

  10. PIP2 controls voltage-sensor movement and pore opening of Kv channels through the S4-S5 linker.

    Science.gov (United States)

    Rodriguez-Menchaca, Aldo A; Adney, Scott K; Tang, Qiong-Yao; Meng, Xuan-Yu; Rosenhouse-Dantsker, Avia; Cui, Meng; Logothetis, Diomedes E

    2012-09-04

    Voltage-gated K(+) (Kv) channels couple the movement of a voltage sensor to the channel gate(s) via a helical intracellular region, the S4-S5 linker. A number of studies link voltage sensitivity to interactions of S4 charges with membrane phospholipids in the outer leaflet of the bilayer. Although the phospholipid phosphatidylinositol-4,5-bisphosphate (PIP(2)) in the inner membrane leaflet has emerged as a universal activator of ion channels, no such role has been established for mammalian Kv channels. Here we show that PIP(2) depletion induced two kinetically distinct effects on Kv channels: an increase in voltage sensitivity and a concomitant decrease in current amplitude. These effects are reversible, exhibiting distinct molecular determinants and sensitivities to PIP(2). Gating current measurements revealed that PIP(2) constrains the movement of the sensor through interactions with the S4-S5 linker. Thus, PIP(2) controls both the movement of the voltage sensor and the stability of the open pore through interactions with the linker that connects them.

  11. 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.

  12. Research on On-Line Coordinated Control Strategy to Improve the Voltage Vulnerability after Disturbance

    Institute of Scientific and Technical Information of China (English)

    Qun-Ying Liu; Qi-Fang Liu; Deng Liu; Yong-Feng Liao

    2014-01-01

    The on-line coordinated control strategy among multi-voltage controls is important to keep voltage security in post-fault systems. Based on the wide area measuring information, the energy function, which can qualify the impacts of the different control actions on voltage of different nodes, is proposed. And then, considering the impacts of different control actions on the node voltage being treated as a weight matrix, the energy margin is used as the objective function and the reactive power margin is innovatively used as the constraint to regulate the control actions globally according to the weight values. At last, the objective functions are solved to get the optimal global coordinated control strategies. The proposed method is identified in an IEEE-30 Bus system and the simulation results show that it effectively improves the voltage stability.

  13. Cooperative Control with Virtual Selective Harmonic Capacitance for Harmonic Voltage Compensation in Islanded MicroGrids

    DEFF Research Database (Denmark)

    Micallef, A.; Apap, M.; Spitero-Stanies, C.

    2012-01-01

    This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. Inverters...... having LCL output filters would cause voltage distortion to be present at the PCC of the local load when non-linear current is supplied to the load due to the voltage drop across the grid side inductor. Techniques to reduce the output voltage distortion typically consist of installing either passive...... loop, implemented in each of the microsource inverters, is proposed so as to dampen the voltage harmonics at the PCC of the local load. Simulation results are presented showing the suitability of the proposed algorithm in dampening the PCC voltage harmonics....

  14. A charge-pump 60kV modulator for the ISOLDE target extraction voltage

    CERN Document Server

    Barlow, R A; Fowler, A; Gaudillet, H; Gharsa, T; Schipper, J

    2015-01-01

    The ISOLDE facility at CERN provides radioactive ion beams to a number of experimental stations. These ions are produced by a metal target, floating at 60 kV, which is impacted by a 1.4 GeV high intensity proton beam. The ions are then accelerated by a grounded extraction electrode to 60 keV, before transport to the experimental area. During proton beam impact extremely high ionisation of the volume around the target gives rise to significant leakage current which results in loss of charge on the effective target capacitance of approximately 6 nF. If short life-time isotopes are to be studied, the 60 kV must be re-established within a maximum of 10 ms. Recharging the target capacitance to 60 kV and to the required stability of better than 10-4 precludes a direct charging system and an alternative method of re-establishing the 60 kV is used. The present system [1], in operation since 1991, employs a resonant circuit which is triggered 35 µs prior to beam impact. This circuit transfers the charge on the effec...

  15. Control of donor charge states with the tip of a scanning tunnelling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Teichmann, K.; Wenderoth, M.; Loth, S.; Ulbrich, R.G. [IV. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany); Garlef, J.K.; Wijnheijmer, A.P.; Koenraad, P.M. [PSN, Eindhoven University of Technology (Netherlands)

    2009-07-01

    The functionality of nanoscale semiconductor devices crucially depends on details of the electrostatic potential landscape on the atomic scale and its microscopic response to external electric fields. We report here an investigation of charge state switching of buried single Si donors in 6.10{sup 18} cm{sup -3} n-doped GaAs with scanning tunnelling microscopy (STM) under UHV conditions at 5 K. The effect of tip induced band bending (TIBB) through the freshly cleaved (110)-surface was used to change the charge state of individual donors from neutral to positively charged and reverse. Scanning tunnelling spectroscopy (STS) revealed a ring like feature around each donor center. The ring radius depends on tip bias voltage. The charge state of each donor in the random arrangement of dopants was in most cases unambiguously fixed by the extension of the tip-induced space charge cloud, which was located under the tip and controlled by the applied voltage. For certain geometric configurations the system showed bi- (or multi-) stable behaviour, this lead to dynamic flickering of the ionization sequence.

  16. A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2009-04-01

    Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.

  17. A Saturated Output Feedback Controller for the Three Phase Voltage Sourced Reversible Boost Type Rectifier

    NARCIS (Netherlands)

    Escobar, Gerardo; Ortega, Romeo; Schaft, Arjan J. van der

    1998-01-01

    In this article, we present a saturating controller to regulate the output voltage load in a three phase Boost type rectifier. The controller only needs the output voltage signal to be implemented. Moreover, by forcing the inductance currents to track desired suitable sinusoidal signals in phase wit

  18. A Hybrid Optimization Method for Reactive Power and Voltage Control Considering Power Loss Minimization

    DEFF Research Database (Denmark)

    Liu, Chengxi; Qin, Nan; Bak, Claus Leth;

    2015-01-01

    This paper proposes a hybrid optimization method to optimally control the voltage and reactive power with minimum power loss in transmission grid. This approach is used for the Danish automatic voltage control (AVC) system which is typically a non-linear non-convex problem mixed with both continu...

  19. Supervisory hybrid model predictive control for voltage stability of power networks

    NARCIS (Netherlands)

    Negenborn, R.R.; Beccuti, A.G.; Demiray, T.; Leirens, S.; Damm, G.; De Schutter, B.; Morari, M.

    2007-01-01

    Emergency voltage control problems in electric power networks have stimulated the interest for the implementation of online optimal control techniques. Briefly stated, voltage instability stems from the attempt of load dynamics to restore power consumption beyond the capability of the transmission a

  20. Wind Power Plant Voltage Control Optimization with Embedded Application of Wind Turbines and Statcom

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Solanas, Jose Ignacio Busca; Zhao, Haoran

    2017-01-01

    Increasing wind power penetration and the size of wind power plants (WPPs) brings challenges to the operation and control of power systems. Most of WPPs are located far from load centers and the short circuit ratio at the point of common coupling (PCC) is low. The fluctuations of wind power...... will cause voltage variations. An optimal voltage control scheme for WPPs with STATCOMs is presented in the paper. It ensures that the voltages within the WPPs and at the high voltage side of the WPPs are within the limits and maximizes the dynamic Var reserve of the WPPs. Case studies were conducted...

  1. Investigation of Transformer Winding Architectures for High Voltage Capacitor Charging Applications

    DEFF Research Database (Denmark)

    Schneider, Henrik; Thummala, Prasanth; Huang, Lina

    2014-01-01

    Transformer parameters such as leakage inductance and self-capacitance are rarely calculated in advance during the design phase, because of the complexity and huge analytical error margins caused by practical winding implementation issues. Thus, choosing one transformer architecture over another...... for a given design is usually based on experience or a trial and error approach. This work presents equations regarding calculation of leakage inductance, self-capacitance and AC resistance in transformer winding architectures, ranging from the common non-interleaved primary/secondary winding architecture......, to an interleaved, sectionalized and bank winded architecture. The analytical results are evaluated experimentally and through FEM simulations. Different transformer winding architectures are investigated in terms of the losses caused by the transformer parasitics for a bidirectional high-voltage (~1500 V) flyback...

  2. Voltage sensor charge loss accounts for most cases of hypokalemic periodic paralysis.

    Science.gov (United States)

    Matthews, E; Labrum, R; Sweeney, M G; Sud, R; Haworth, A; Chinnery, P F; Meola, G; Schorge, S; Kullmann, D M; Davis, M B; Hanna, M G

    2009-05-05

    Several missense mutations of CACNA1S and SCN4A genes occur in hypokalemic periodic paralysis. These mutations affect arginine residues in the S4 voltage sensors of the channel. Approximately 20% of cases remain genetically undefined. We undertook direct automated DNA sequencing of the S4 regions of CACNA1S and SCN4A in 83 cases of hypokalemic periodic paralysis. We identified reported CACNA1S mutations in 64 cases. In the remaining 19 cases, mutations in SCN4A or other CACNA1S S4 segments were found in 10, including three novel changes and the first mutations in channel domains I (SCN4A) and III (CACNA1S). All mutations affected arginine residues, consistent with the gating pore cation leak hypothesis of hypokalemic periodic paralysis. Arginine mutations in S4 segments underlie 90% of hypokalemic periodic paralysis cases.

  3. Subnanowatt carbon nanotube complementary logic enabled by threshold voltage control.

    Science.gov (United States)

    Geier, Michael L; Prabhumirashi, Pradyumna L; McMorrow, Julian J; Xu, Weichao; Seo, Jung-Woo T; Everaerts, Ken; Kim, Chris H; Marks, Tobin J; Hersam, Mark C

    2013-10-09

    In this Letter, we demonstrate thin-film single-walled carbon nanotube (SWCNT) complementary metal-oxide-semiconductor (CMOS) logic devices with subnanowatt static power consumption and full rail-to-rail voltage transfer characteristics as is required for logic gate cascading. These results are enabled by a local metal gate structure that achieves enhancement-mode p-type and n-type SWCNT thin-film transistors (TFTs) with widely separated and symmetric threshold voltages. These complementary SWCNT TFTs are integrated to demonstrate CMOS inverter, NAND, and NOR logic gates at supply voltages as low as 0.8 V with ideal rail-to-rail operation, subnanowatt static power consumption, high gain, and excellent noise immunity. This work provides a direct pathway for solution processable, large area, power efficient SWCNT advanced logic circuits and systems.

  4. Smart Demand for Improving Short-term Voltage Control on Distribution Networks

    DEFF Research Database (Denmark)

    Garcia-Valle, Rodrigo; P. Da Silva, Luiz C.; Xu, Zhao

    2009-01-01

    customer integration to aid power system performance is almost inevitable. This study introduces a new type of smart demand side technology, denoted demand as voltage controlled reserve (DVR), to improve short-term voltage control, where customers are expected to play a more dynamic role to improve voltage...... control. The technology can be provided by thermostatically controlled loads as well as other types of load. This technology is proven to be effective in case of distribution systems with a large composition of induction motors, where the voltage presents a slow recovery characteristic due to deceleration...... of the motors during faults. This study presents detailed models, discussion and simulation tests to demonstrate the technical viability and effectiveness of the DVR technology for short-term voltage control....

  5. An improved control method of power electronic converters in low voltage micro-grid

    DEFF Research Database (Denmark)

    Xiaofeng, Sun; Qingqiu, Lv; Yanjun, Tian

    2011-01-01

    control of the voltage and frequency deviation added to power references could achieve secondary regulation of the voltage and frequency. In this paper, the authors take the steady and transient transition of grid connecting and disconnecting of the micro-grid as an example, and demonstrate...... the place. The conventional droop control can perform the energy management in grid-connected mode, but may not so effective when micro-grid transferring between grid-connected mode and island mode. The paper analysis the micro-grid in different modes (Conventional droop control, Voltage reference...... compensation, Constant power output mode, Phase adjustment mode), and then proposes an overall control strategy for the micro-grid. The voltage reference compensation would minimize the steady-state error on the nominated operation point; the coordinate control of voltage and frequency with a feed forward...

  6. Hierarchical Control with Virtual Resistance Optimization for Efficiency Enhancement and State-of-Charge Balancing in DC Microgrids

    DEFF Research Database (Denmark)

    Meng, Lexuan; Dragicevic, Tomislav; Quintero, Juan Carlos Vasquez

    2015-01-01

    This paper proposes a hierarchical control scheme which applies optimization method into DC microgrids in order to improve the system overall efficiency while considering the State-of-Charge (SoC) balancing at the same time. Primary droop controller, secondary voltage restoration controller...... and tertiary optimization tool formulate the complete hierarchical control system. Virtual resistances are taken as the decision variables for achieving the objective. simulation results are presented to verify the proposed approach....

  7. Voltage Control Method Using Distributed Generators Based on a Multi-Agent System

    Directory of Open Access Journals (Sweden)

    Hyun-Koo Kang

    2015-12-01

    Full Text Available This paper presents a voltage control method using multiple distributed generators (DGs based on a multi-agent system framework. The output controller of each DG is represented as a DG agent, and each voltage-monitoring device is represented as a monitoring agent. These agents cooperate to accomplish voltage regulation through a coordinating agent or moderator. The moderator uses the reactive power sensitivities and margins to determine the voltage control contributions of each DG. A fuzzy inference system (FIS is employed by the moderator to manage the decision-making process. An FIS scheme is developed and optimized to enhance the efficiency of the proposed voltage control process using particle swarm optimization. A simple distribution system with four voltage-controllable DGs is modeled, and an FIS moderator is implemented to control the system. Simulated data show that the proposed voltage control process is able to maintain the system within the operating voltage limits. Furthermore, the results were similar to those obtained using optimal power flow calculations, even though little information on the power system was required and no power flow calculations were implemented.

  8. An optical remote controlled high voltage dome for electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, S. [The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Kapp, O.H. [The Department of Radiology and the Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

    1995-08-01

    A low cost high voltage dome has been completed for an electron microscope with a thermal emission tip as electron source. Two fibers are used to provide communication across the high electrical field zone between the computer and the dome. This system provides a reliable method to operate the dome circuitry (floating at high voltage) and ensures the safety of both the computer system and the operator. Because of the application of ``dummy`` serial data transfer, the least number of fibers and associated components are used, providing a relatively low-cost solution to this problem. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  9. Charged grain boundaries reduce the open-circuit voltage of polycrystalline solar cells—An analytical description

    Science.gov (United States)

    Gaury, Benoit; Haney, Paul M.

    2016-12-01

    Analytical expressions are presented for the dark current-voltage relation J(V) of a pn+ junction with positively charged columnar grain boundaries with high defect density. These expressions apply to non-depleted grains with sufficiently high bulk hole mobilities. The accuracy of the formulas is verified by direct comparison to numerical simulations. Numerical simulations further show that the dark J(V) can be used to determine the open-circuit potential Voc of an illuminated junction for a given short-circuit current density Jsc . A precise relation between the grain boundary properties and Voc is provided, advancing the understanding of the influence of grain boundaries on the efficiency of thin film polycrystalline photovoltaics like CdTe and Cu(In,Ga)Se2 .

  10. Dynamical model of series-resonant converter with peak capacitor voltage predictor and switching frequency control

    Science.gov (United States)

    Pietkiewicz, A.; Tollik, D.; Klaassens, J. B.

    1989-08-01

    A simple small-signal low-frequency model of an idealized series resonant converter employing peak capacitor voltage prediction and switching frequency control is proposed. Two different versions of the model describe all possible conversion modes. It is found that step down modes offer better dynamic characteristics over most important network functions than do the step-up modes. The dynamical model of the series resonant converter with peak capacitor voltage prediction and switching frequency programming is much simpler than such popular control stategies as frequency VCO (voltage controlled oscillators) based control, or diode conduction angle control.

  11. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    Directory of Open Access Journals (Sweden)

    Feri Yusivar

    2014-12-01

    Full Text Available Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likely unstable. The DC-link control system is modeled, simulated, and mathematically analyzed so the parameter specification for the stable system can be obtained.

  12. Charged residues distribution modulates selectivity of the open state of human isoforms of the voltage dependent anion-selective channel.

    Science.gov (United States)

    Amodeo, Giuseppe Federico; Scorciapino, Mariano Andrea; Messina, Angela; De Pinto, Vito; Ceccarelli, Matteo

    2014-01-01

    Voltage Dependent Anion-selective Channels (VDACs) are pore-forming proteins located in the outer mitochondrial membrane. They are responsible for the access of ions and energetic metabolites into the inner membrane transport systems. Three VDAC isoforms exist in mammalian, but their specific role is unknown. In this work we have performed extensive (overall ∼5 µs) Molecular Dynamics (MD) simulations of the human VDAC isoforms to detect structural and conformational variations among them, possibly related to specific functional roles of these proteins. Secondary structure analysis of the N-terminal domain shows a high similarity among the three human isoforms of VDAC but with a different plasticity. In particular, the N-terminal domain of the hVDAC1 is characterized by a higher plasticity, with a ∼20% occurrence for the 'unstructured' conformation throughout the folded segment, while hVDAC2, containing a peculiar extension of 11 amino acids at the N-terminal end, presents an additional 310-helical folded portion comprising residues 10' to 3, adhering to the barrel wall. The N-terminal sequences of hVDAC isoforms are predicted to have a low flexibility, with possible consequences in the dynamics of the human VDACs. Clear differences were found between hVDAC1 and hVDAC3 against hVDAC2: a significantly modified dynamics with possible important consequence on the voltage-gating mechanism. Charge distribution inside and at the mouth of the pore is responsible for a different preferential localization of ions with opposite charge and provide a valuable rationale for hVDAC1 and hVDAC3 having a Cl-/K+ selectivity ratio of 1.8, whereas hVDAC2 of 1.4. Our conclusion is that hVDAC isoforms, despite sharing a similar scaffold, have modified working features and a biological work is now requested to give evidence to the described dissimilarities.

  13. Voltage margin control for offshore multi-use platform integration

    DEFF Research Database (Denmark)

    Mier, V.; Casielles, P.G.; Koto, J.

    terminal VSC-MTDC which includes offshore generation, storage, loads and ac connection, was modeled and simulated in DigSILENT Power Factory software. Voltage margin method has been used for reliable operation of the MTDC system without the need of fast communication. Simulation results show...

  14. Secondary Frequency and Voltage Control of Islanded Microgrids via Distributed Averaging

    DEFF Research Database (Denmark)

    W. Simpson-Porco, John; Shafiee, Qobad; Dorfler, Florian

    2015-01-01

    actions. The frequency controller rapidly regulates the microgrid frequency to its nominal value while maintaining active power sharing among the distributed generators. Tuning of the voltage controller provides a simple and intuitive trade-off between the conflicting goals of voltage regulation......In this work we present new distributed controllers for secondary frequency and voltage control in islanded microgrids. Inspired by techniques from cooperative control, the proposed controllers use localized information and nearest neighbour communication to collectively perform secondary control...... and reactive power sharing. Our designs require no knowledge of the microgrid topology, impedances or loads. The distributed architecture allows for flexibility and redundancy, and eliminates the need for a central microgrid controller. We provide a voltage stability analysis and present extensive experimental...

  15. Optimized Controller Design for a 12-Pulse Voltage Source Converter Based HVDC System

    Science.gov (United States)

    Agarwal, Ruchi; Singh, Sanjeev

    2017-08-01

    The paper proposes an optimized controller design scheme for power quality improvement in 12-pulse voltage source converter based high voltage direct current system. The proposed scheme is hybrid combination of golden section search and successive linear search method. The paper aims at reduction of current sensor and optimization of controller. The voltage and current controller parameters are selected for optimization due to its impact on power quality. The proposed algorithm for controller optimizes the objective function which is composed of current harmonic distortion, power factor, and DC voltage ripples. The detailed designs and modeling of the complete system are discussed and its simulation is carried out in MATLAB-Simulink environment. The obtained results are presented to demonstrate the effectiveness of the proposed scheme under different transient conditions such as load perturbation, non-linear load condition, voltage sag condition, and tapped load fault under one phase open condition at both points-of-common coupling.

  16. PSO-Based Voltage Control Strategy for Loadability Enhancement in Smart Power Grids

    Directory of Open Access Journals (Sweden)

    Heng-Yi Su

    2016-12-01

    Full Text Available This paper proposes a new voltage control methodology using the particle swarm optimization (PSO technique for smart grid loadability enhancement. The goal of this paper is to achieve reliable and efficient voltage profile/stability regulation in power grids. This methodology is based on the decouple power flow equations and the worst-case design technique. Specifically, the secondary voltage control (SVC problem is formulated as an L-infinity norm minimization problem which considers overall load voltage deviations in electrical power systems as an objective model, and the PSO technique is employed to determine a robust control action which aims to improve voltage profile and to enlarge transmission grid loadability by optimal coordinated control of VAR sources. The methodology was successfully tested on several IEEE benchmark systems.

  17. Effect of semiconductor-controlled voltage injection by UPFC and ULTC on power system stability

    Science.gov (United States)

    Alavian Mehr, Alireza

    Commercial availability of various power semiconductor switches indicates proliferation of power electronic based apparatus in utility power systems. Furthermore, existing power system apparatus, e.g. mechanical phase shifters and mechanical tap changing transformers, will be retrofitted to utilize higher switching speed of semiconductor switches. A group of these apparatus, i.e., unified power flow controller (UPFC), static phase shifter (SPS), under-load tap-changing (ULTC) transformer and static series capacitor (SSC), perform their respective functions by means of injecting series controlled voltages in power systems. This thesis demonstrates that fast series voltage injection, for dynamic power flow regulation, can result in voltage dynamics and even voltage instability. This indicates that fast voltage injection by means of power electronic based apparatus can couple voltage stability and angle stability phenomena. To investigate this coupling phenomena, the voltage dependency of the load must be adequately represented in the load model. The reported studies in this work are based on representing the load by a combination of static and dynamic loads. This thesis primarily investigates impacts of UPFC and semiconductor-controlled ULTC on voltage stability and angle stability phenomena. An eigen analysis approach is used for the studies. The eigen analysis results are validated by digital time-domain simulations using a transient stability software. Both the eigen analysis and the transient stability software tools are tailored to account for angle and voltage stability phenomena.

  18. A Method for Compensating Customer Voltage Drops due to Nighttime Simultaneous Charging of EVs Utilizing Reactive Power Injection from Battery Chargers

    Science.gov (United States)

    Noda, Taku; Kabasawa, Yuichiro; Fukushima, Kentaro; Nemoto, Koshichi; Uemura, Satoshi

    When we consider the global warming, the reduction of CO2 emission is one of the most important problems which require urgent solutions. One option is to integrate low-CO2-emission generators to the grid as much as possible. Another option is to replace inefficient vehicles based on internal-combustion engines with electric ones (EVs). Due to the latter, we can easily estimate that most consumers will charge EVs' batteries at nighttime. Thus, excessive voltage drops due to the nighttime simultaneous charging are supposed to be a possible future problem. This paper proposes a method for compensating the voltage drops by injecting reactive power from EV battery chargers.

  19. Surface Charging Controlling of the Chinese Space Station with Hollow Cathode Plasma Contactor

    Science.gov (United States)

    Jiang, Kai; Wang, Xianrong; Qin, Xiaogang; Yang, Shengsheng; Yang, Wei; Zhao, Chengxuan; Chen, Yifeng; Shi, Liang; Tang, Daotan; Xie, Kan

    2016-07-01

    A highly charged manned spacecraft threatens the life of an astronaut and extravehicular activity, which can be effectively reduced by controlling the spacecraft surface charging. In this article, the controlling of surface charging on Chinese Space Station (CSS) is investigated, and a method to reduce the negative potential to the CSS is the emission electron with a hollow cathode plasma contactor. The analysis is obtained that the high voltage (HV) solar array of the CSS collecting electron current can reach 4.5 A, which can be eliminated by emitting an adequate electron current on the CSS. The theoretical analysis and experimental results are addressed, when the minimum xenon flow rate of the hollow cathode is 4.0 sccm, the emission electron current can neutralize the collected electron current, which ensures that the potential of the CSS can be controlled in a range of less than 21 V, satisfied with safety voltage. The results can provide a significant reference value to define a flow rate to the potential controlling programme for CSS.

  20. The effect of the dc bias voltage on the x-ray bremsstrahlung and beam intensities of medium and highly charged ions of argon.

    Science.gov (United States)

    Rodrigues, G; Lakshmy, P S; Baskaran, R; Kanjilal, D; Roy, A

    2010-02-01

    X-ray bremsstrahlung measurements from the 18 GHz High Temperature Superconducting Electron Cyclotron Resonance Ion Source, Pantechnik-Delhi Ion Source were measured as a function of negative dc bias voltage, keeping all other source operating parameters fixed and the extraction voltage in the off condition. The optimization of medium and highly charged ions of argon with similar source operating parameters is described. It is observed that the high temperature component of the electron is altered significantly with the help of bias voltage, and the electron population has to be maximized for obtaining higher current.

  1. Transmission Power Control using Small-Capacity UPFC under Output Voltage Saturation

    Science.gov (United States)

    Kuroda, Takeshi; Takeshita, Takaharu; Fujita, Hideki

    This paper presents a fast transmission power control scheme using a UPFC (Unified Power Flow Controller) under the output voltage saturation. For practical use of the UPFC, the fast and stable power response and the reduced power converter capacity are desired. The authors propose the fast and stable control scheme under the output voltage saturation of the reduced capacity UPFC. The effectiveness of the proposed control algorithm of the UPFC has been verified by experiments.

  2. Voltage Support from Electric Vehicles in Distribution Grid

    DEFF Research Database (Denmark)

    Huang, Shaojun; Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

    2013-01-01

    , the combination of these two methods is also examined for controlled EV charging. Simulation results show that the combination of the two individual supporting methods has the best performance in terms of voltage regulation as well as improving EV penetration level at weak distribution grids.......The paper evaluates the voltage support functions from electric vehicles (EVs) on a typical Danish distribution grid with high EV penetration. In addition to the popular voltage control modes, such as voltage droop charging (low voltage level leads to low charging power) and reactive power support...

  3. A NEW STRUCTURE AND ITS ANALYTICAL BREAKDOWN MODEL OF HIGH VOLTAGE SOI DEVICE WITH STEP UNMOVABLE SURFACE CHARGES OF BURIED OXIDE LAYER

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new SOI (Silicon On Insulator) high voltage device with Step Unmovable Surface Charges(SUSC) of buried oxide layer and its analytical breakdown model are proposed in the paper. The unmovable charges are implemented into the upper surface of buried oxide layer to increase the vertical electric field and uniform the lateral one. The 2-D Poisson's equation is solved to demonstrate the modulation effect of the immobile interface charges and analyze the electric field and breakdown voltage with the various geometric parameters and step numbers. A new RESURF (REduce SURface Field) condition of the SOI device considering the interface charges and buried oxide is derived to maximize breakdown voltage. The analytical results are in good agreement with the numerical analysis obtained by the 2-D semiconductor devices simulator MEDICI. As a result, an 1200V breakdown voltage is firstly obtained in 3μm-thick top Si layer, 2μm-thick buried oxide layer and 70μm-length drift region using a linear doping profile of unmovable buried oxide charges.

  4. Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    MILOUD, Y.

    2010-08-01

    Full Text Available This paper proposes the space vector pulse width modulation (SVPWM control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load�s disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy.

  5. 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

    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......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...

  6. Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier

    Directory of Open Access Journals (Sweden)

    Yin Hongren

    2012-09-01

    Full Text Available Euler-Lagrange (EL model of voltage source PWM rectifier is set up based on its model in synchronous dq coordinates. Passivity based controller is designed on the basis of passivity and EL model of voltage source PWM rectifier. Three switching function are educed by passivity based controller. A switching function is only realized in engineering consequently. Voltage source PWM rectifier using passivity based controller has many advantages, such as simpler structure, low total harmonic distortion, and good disturbance rejection performance. Passivity based control law is proved feasible by simulink simulation.  

  7. A Robust Control Scheme for Medium-Voltage-Level DVR Implementation

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Li, Yun Wei;

    2007-01-01

    In this paper, a robust control scheme with an outer Hinfin voltage control loop and an inner current control loop is designed and implemented on a medium-voltage (MV)-level dynamic voltage restorer (DVR) system. Through a simple selection of weighting functions, the synthesized Hinfin controller....../nonlinear load and induction motor load) conditions. It is shown that the proposed control scheme is effective in both balanced and unbalanced sag compensation and load disturbance rejection, as its robustness is explicitly specified....... of Hinfin controller weighting function selection, inner current loop tuning, and system disturbance rejection capability is presented. Finally, the designed control scheme is extensively tested on a laboratory 10-kV MV-level DVR system with varying voltage sag (balanced and unbalanced) and loading (linear...

  8. An Experimental Study on Voltage Compensation Method using Autonomous Decentralized Control of Distributed Generators

    Science.gov (United States)

    Tanaka, Shunsuke; Suzuki, Hirokazu

    When many distributed generators (DGs) are connected to a distribution line, the upward power flow from DGs causes the difficulty in line voltage regulation. As the countermeasure, we propose several methods to control the line voltage by use of DGs' reactive power outputs. These methods using only DGs' reactive power are implemented in an autonomous decentralized way. DGs with the function to estimate the line impedance provide the power system with reactive power according to the estimated impedance value, and regulate the line voltage. We evaluate the effect of the proposed methods for voltage compensation by experimental studies using commercial grid-connected inverters for PV system.

  9. Tunable sensor response by voltage-control in biomimetic hair flow sensors

    NARCIS (Netherlands)

    Droogendijk, H.; Krijnen, G.J.M.

    2012-01-01

    We report improvements in detection limit and responsivity of biomimetic hair flow sensors by electrostatic spring-softening (ESS). Applying a DC-bias voltage to our capacitive flow sensors mediates large (80% and more) voltage-controlled electromechanical amplification of the flow signal for freque

  10. Tunable sensor response by voltage-control in biomimetic hair flow sensors

    NARCIS (Netherlands)

    Droogendijk, H.; Krijnen, G.J.M.

    2012-01-01

    We report improvements in detection limit and responsivity of biomimetic hair flow sensors by electrostatic spring-softening (ESS). Applying a DC-bias voltage to our capacitive flow sensors mediates large (80% and more) voltage-controlled electro-mechanical amplification of the flow signal for frequ

  11. 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 (...... verified by time domain simulations using MATLAB-Simulink....

  12. Active gate driver for dv/dt control and active voltage clamping in an IGBT stack

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    2005-01-01

    For high voltages converters stacks of IGBTs can be used if the static and dynamic voltage sharing among the IGBTs can be applied. dVCE/dt should also be controlled in order not to damage insulation material. This paper describes theory and measurements of an active gate driver for stacking IGBTs...

  13. Voltage controlled terahertz transmission through GaN quantum wells

    OpenAIRE

    Laurent, T.; Sharma, R.; Torres, J.; Nouvel, P; Blin, S.; Varani, L.; Cordier, Y.; Chmielowska, M.; Chenot, S.; Faurie, JP; Beaumont, B.; P. Shiktorov; Starikov, E.; Gruzinskis, V.; Korotyevyev, V.

    2011-01-01

    We report measurements of radiation transmission in the 0.220--0.325 THz frequency domain through GaN quantum wells grown on sapphire substrates at room and low temperatures. A significant enhancement of the transmitted beam intensity with the applied voltage on the devices under test is found. For a deeper understanding of the physical phenomena involved, these results are compared with a phenomenological theory of light transmission under electric bias relating the transmission enhancement ...

  14. Lithium-Ion Cell Charge-Control Unit Developed

    Science.gov (United States)

    Reid, Concha M.; Manzo, Michelle A.; Buton, Robert M.; Gemeiner, Russel

    2005-01-01

    A lithium-ion (Li-ion) cell charge-control unit was developed as part of a Li-ion cell verification program. This unit manages the complex charging scheme that is required when Li-ion cells are charged in series. It enables researchers to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and reduces test costs substantially in comparison to individual cell testing.

  15. Molecular dissection of the contribution of negatively and positively charged residues in S2, S3, and S4 to the final membrane topology of the voltage sensor in the K+ channel, KAT1.

    Science.gov (United States)

    Sato, Yoko; Sakaguchi, Masao; Goshima, Shinobu; Nakamura, Tatsunosuke; Uozumi, Nobuyuki

    2003-04-11

    Voltage-dependent ion channels control changes in ion permeability in response to membrane potential changes. The voltage sensor in channel proteins consists of the highly positively charged segment, S4, and the negatively charged segments, S2 and S3. The process involved in the integration of the protein into the membrane remains to be elucidated. In this study, we used in vitro translation and translocation experiments to evaluate interactions between residues in the voltage sensor of a hyperpolarization-activated potassium channel, KAT1, and their effect on the final topology in the endoplasmic reticulum (ER) membrane. A D95V mutation in S2 showed less S3-S4 integration into the membrane, whereas a D105V mutation allowed S4 to be released into the ER lumen. These results indicate that Asp(95) assists in the membrane insertion of S3-S4 and that Asp(105) helps in preventing S4 from being releasing into the ER lumen. The charge reversal mutation, R171D, in S4 rescued the D105R mutation and prevented S4 release into the ER lumen. A series of constructs containing different C-terminal truncations of S4 showed that Arg(174) was required for correct integration of S3 and S4 into the membrane. Interactions between Asp(105) and Arg(171) and between negative residues in S2 or S3 and Arg(174) may be formed transiently during membrane integration. These data clarify the role of charged residues in S2, S3, and S4 and identify posttranslational electrostatic interactions between charged residues that are required to achieve the correct voltage sensor topology in the ER membrane.

  16. Electrostatic charging and control of droplets in microfluidic devices.

    Science.gov (United States)

    Zhou, Hongbo; Yao, Shuhuai

    2013-03-07

    Precharged droplets can facilitate manipulation and control of low-volume liquids in droplet-based microfluidics. In this paper, we demonstrate non-contact electrostatic charging of droplets by polarizing a neutral droplet and splitting it into two oppositely charged daughter droplets in a T-junction microchannel. We performed numerical simulation to analyze the non-contact charging process and proposed a new design with a notch at the T-junction in aid of droplet splitting for more efficient charging. We experimentally characterized the induced charge in droplets in microfabricated devices. The experimental results agreed well with the simulation. Finally, we demonstrated highly effective droplet manipulation in a path selection unit appending to the droplet charging. We expect our work could enable precision manipulation of droplets for more complex liquid handling in microfluidics and promote electric-force based manipulation in 'lab-on-a-chip' systems.

  17. 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.

  18. Voltage Control Scheme for Three Phase SVM Inverter Fed Induction Motor Drive Systems

    Directory of Open Access Journals (Sweden)

    U. SOWMMIYA

    2010-12-01

    Full Text Available This paper presents an efficient implementation scheme for the closed-loop voltage control of an induction motor incorporating ‘Space Vector Pulse Width Modulation (SVPWM‘. Voltage control is required to meet the variation in the input voltage and to regulate the output of the inverter. Space Vector Modulation (SVM is an algorithm for the control of Pulse Width Modulation (PWM. Comparative study has been made between SVM and PWM techniques. From the simulation results, SVM has reduced THD compared to pulse width modulation techniques. Thus, SVM gives better harmonic response and higher efficiency.

  19. Voltage magnitude and margin controller for remote industrial microgrid with high wind penetration

    DEFF Research Database (Denmark)

    Cai, Yu; Lin, Jin; Song, Yonghua

    2013-01-01

    It is well known that the remote industrial microgrid is located at the periphery of the grid, which is weakly connected to the main grid. In order to enhance the voltage stability and ensure a good power quality for industries, a voltage magnitude and margin controller based on wind turbines...... is proposed in this paper. This controller includes two parts to improve voltage stability in different time scales by using local measurements. Case studies conducted for a remote microgrid with high wind penetration have proved the effectiveness of the proposed control scheme....

  20. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  1. 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

    is implemented in the power system simulation toolbox PowerFactory DIgSILENT. The DFIG wind farm ride-through capability and contribution to voltage control in the power system are assessed and discussed by means of simulations with the use of a transmission power system generic model developed and delivered......-side converter as long as it is not blocked by the protection system, otherwise the grid-side converter takes over the voltage control. Moreover, the article presents a DFIG wind farm model equipped with a grid fault protection system and the described co-ordinated voltage control. The whole DFIG wind farm model...... by the Danish Transmission System Operator Energinet.dk. The simulation results show how a DFIG wind farm equipped with voltage control can help a nearby active stall wind farm to ride through a grid fault, without implementation of any additional ride-through control strategy in the active stall wind farm....

  2. Controlled operation of the Islanded portion of the CIGRE Low Voltage distribution network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Bak, Claus Leth;

    2017-01-01

    be switched to the Voltage-Frequency (VF) control mode. In case of islanding, the network loses it slack reference and this reference is established by the use of VF controller. The voltage and the frequency of the islanded MG deviate when it is disconnected from the transmission grid and these deviations...... are according to the load-generation imbalance in the islanded MG. The voltage and the frequency of the islanded MG can be restored to the permissible limits if the desired/exceeded amount of active and reactive power is injected/absorbed by the locally available sources in islanded MG. This paper proposes...... the control strategy which can compensate the problems of the voltage and the frequency deviations in the islanded MG. The selection of the VF controller for the most suitable DG unit of the LV test network is also presented in this paper and effectiveness of the controllers is verified by presenting...

  3. Study on Optimization Strategy for Voltage and Reactive Power Control of Wind Farm

    Science.gov (United States)

    Lu, Q.; Shi, L.; Chen, N.

    A method for calculating reactive power limit of wind farm comprised of doubly-fed induction generators (DFIG) is proposed. The reactive power limit of wind farm is the sum of reactive power limit of DFIGs which is calculated by the method considering static stability margin. Based on this, reactive power control of wind farm is discussed and proposed. The proposed reactive power control is divided into different control modes according to power factor of high voltage side in wind farm substation and voltage of low voltage side in point of interconnection(POI). In different control modes, different control objects are applied on reactive power regulation. After reactive power regulation is finished, some reactive power of wind farm should be released. At last, numerical test system is established, the result shows that the proposed method is effective to support voltage of POI

  4. Coordinated voltage control in smart grids subject to a fair contribution of reactive power

    Energy Technology Data Exchange (ETDEWEB)

    Kolenc, Marko; Papic, Igor; Blazic, Bostjan [Ljubljana Univ. (Slovenia). Faculty of Electrical Engineering

    2012-07-01

    The paper analyses the influence of distributed generation (DG) on voltage profile and distribution losses. Connection of DG units to a distribution network results in a local voltage increase and usually reduction of losses. The focus of the paper is on development of a control strategy to keep the voltage within permissible limits, minimize losses and assure fairness regarding reactive power contributions. As the new technologies nowadays allow bidirectional data flow in almost real time, more active participation of generators in voltage control is possible. Different solutions were evaluated by means of simulations. The simulated network was an actual Slovenian medium-voltage distribution network which covers a large area with diverse feeders and thus gives relatively general results. The network was modified by increasing the number of DG (especially photovoltaic) as the growth of DG is very fast in Slovenia. (orig.)

  5. Switchable voltage control of the magnetic coercive field via magnetoelectric effect

    Science.gov (United States)

    Wang, Jing; Ma, Jing; Li, Zheng; Shen, Yang; Lin, Yuanhua; Nan, C. W.

    2011-08-01

    Switchable voltage modulation of the magnetic properties is reported in different multiferroic bilayers with magnetic films grown on pre-poled ferroelectric substrates, based on the magneto-optical Kerr effect observations. The dynamic voltage control of the magnetic coercive field (Hc) is dependent not only on the materials properties of each ferroic layer, but also on the bias voltage history. The Hc versus electric field behaviors essentially track the dependence of the piezostrains of the substrates on the bias voltage. The observations demonstrate that Hc in such multiferroic bilayers can be controlled by voltage via strain-mediated magnetoelectric coupling and that the Hc change is not an artifact due to a heating effect.

  6. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  7. Thyristor voltage converter in induction electric drives with microprocessor control

    Energy Technology Data Exchange (ETDEWEB)

    Braslavsky, I.; Zuzev, A.; Shilin, S. [Electric Drive Department, Urals State Technical University, Ekaterinburg (Russian Federation)

    1997-12-31

    The paper consists of some results on developed pulse model of thyristor voltage converter which is one of the most mathematically complicated unit of electric drive. The model structure and model parameter calculating method are represented. The application of the model allows to analyse stability in `locally` by the linear pulse system theory methods with talking into consideration quantise processes within the converter. Such application provides the obtaining higher accurate results comparing with the non-linear system theory approximate methods. Logarithmic frequency characteristics are used to analyse converter dynamic features and they are represented too. (orig.) 4 refs.

  8. High Performance of Space Vector Modulation Direct Torque Control SVM-DTC Based on Amplitude Voltage and Stator Flux Angle

    Directory of Open Access Journals (Sweden)

    Hassan Farhan Rashag

    2013-04-01

    Full Text Available Various aspects related to controlling induction motor are investigated. Direct torque control is an original high performance control strategy in the field of AC drive. In this proposed method, the control system is based on Space Vector Modulation (SVM, amplitude of voltage in direct- quadrature reference frame (d-q reference and angle of stator flux. Amplitude of stator voltage is controlled by PI torque and PI flux controller. The stator flux angle is adjusted by rotor angular frequency and slip angular frequency. Then, the reference torque and the estimated torque is applied to the input of PI torque controller and the control quadrature axis voltage is determined. The control d-axis voltage is determined from the flux calculator. These q and d axis voltage are converted into amplitude voltage. By applying polar to Cartesian on amplitude voltage and stator flux angle, direct voltage and quadratures voltage are generated. The reference stator voltages in d-q are calculated based on forcing the stator voltage error to zero at next sampling period. By applying inverse park transformation on d-q voltages, the stator voltages in &alpha and &beta frame are generated and apply to SVM. From the output of SVM, the motor control signal is generated and the speed of the induction motor regulated toward the rated speed. The simulation Results have demonstrated exceptional performance in steady and transient states and shows that decrease of torque and flux ripples is achieved in a complete speed range.

  9. Ion Transport through Diffusion Layer Controlled by Charge Mosaic Membrane

    Directory of Open Access Journals (Sweden)

    Akira Yamauchi

    2012-01-01

    Full Text Available The kinetic transport behaviors in near interface of the membranes were studied using commercial anion and cation exchange membrane and charge mosaic membrane. Current-voltage curve gave the limiting current density that indicates the ceiling of conventional flux. From chronopotentiometry above the limiting current density, the transition time was estimated. The thickness of boundary layer was derived with conjunction with the conventional limiting current density and the transition time from steady state flux. On the other hand, the charge mosaic membrane was introduced in order to examine the ion transport on the membrane surface in detail. The concentration profile was discussed by the kinetic transport number with regard to the water dissociation (splitting on the membrane surface.

  10. Multi-Inputs/Multi-Outputs control of plasma current and loop voltage on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Nouailletas, R., E-mail: remy.nouailletas@cea.fr [CEA, F-13108 Saint Paul lez Durance (France); Barana, O.; Saint-Laurent, F.; Brémond, S.; Moreau, P.; Ekedahl, A.; Artaud, J.-F. [CEA, F-13108 Saint Paul lez Durance (France)

    2013-10-15

    During a tokamak discharge, several control modes may have to be run in sequence in order to perform the control of the different discharge phases. The transitions between these control modes are not always easy to handle because in most cases the coupling between the controlled plasma quantities is not taken into account in each control mode design process. This paper presents a new Multi-Inputs/Multi-Outputs (MIMO) controller applied on Tore Supra to control both plasma current and flux variations through the central solenoid voltage and the lower hybrid current drive (LHCD) system power. It deals with the transition from a loop voltage floating mode to a loop voltage control mode. The controller, synthesized and tuned using a model-based approach, has been validated in simulation before its successful implementation on Tore Supra experiments.

  11. An Embedded Voltage Harmonic Compensation Strategy for Current Controlled DG Interfacing Converters

    DEFF Research Database (Denmark)

    Zhao, Xin; Meng, Lexuan; Guerrero, Josep M.

    2016-01-01

    Harmonics have been considered as one of the major issues in future power grids. With the increasing demand in advanced control functions, power electronic converter interfaced Distributed Generators (DGs) are expected to perform harmonic compensation when necessary. It has been demonstrated in a...... voltage detection; 3) compared with conventional voltage detection based method, it offers better performance because of direct harmonic voltage regulation. Experimental results are presented to demonstrate the effectiveness of the method....... in a number of studies that DG converters operating in Voltage-Controlled Mode (VCM) can be easily configured to realize voltage harmonic suppression utilizing naturally embedded voltage control loop. While for DG converters operating in Current-Controlled Mode (CCM), such function was rarely studied....... Considering that CCM is commonly used in renewable energy based generators and energy storage systems, it has certain significance to achieve the same function with CCM operated converters. Aiming at such objective, this paper proposes a voltage detection based embedded Harmonic Compensator (HC) for CCM...

  12. Sensorless Control Technology for PMSG base on the Dead-time Compensation voltage

    Directory of Open Access Journals (Sweden)

    Yang Li-yong

    2015-01-01

    Full Text Available In order to improve the speed sensorless-control system of PMSG in low speed performance, this paper introduces a novel Dead-time compensation control method .Mathematical model is established according to the Dead-zone of the influence of the voltage source type inverter output voltage. At the same time, the given value of current regulator output voltage has been fixed based on the established model. Then the stator voltage after compensationed is applied to the flux estimation, which improves the performance of flux estimation. Finally, the position and speed of the rotor is estimated based on Back-Electromotive Force, which has Simple algorithm and good robustness. In order to verify the correctness of theoretical analysis, the experiment was done according to the new control method. The results proved the correctness and feasibility of this control method.

  13. Minimum-Voltage Vector Injection Method for Sensorless Control of PMSM for Low-Speed Operations

    DEFF Research Database (Denmark)

    Xie, Ge; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2016-01-01

    In this paper, a simple signal injection method is proposed for sensorless control of PMSM at low speed, which ideally requires one voltage vector only for position estimation. The proposed method is easy to implement resulting in low computation burden. No filters are needed for extracting...... may also be further developed to inject two opposite voltage vectors to reduce the effects of inverter voltage error on the position estimation accuracy. The effectiveness of the proposed method is demonstrated by comparing with other sensorless control method. Theoretical analysis and experimental...

  14. Multi-Stage Optimization Based Automatic Voltage Control Systems Considering Wind Power Forecasting Errors

    DEFF Research Database (Denmark)

    Qin, Nan; Bak, Claus Leth; Abildgaard, Hans

    2017-01-01

    cost and the generator reactive power output cost. The problem is formulated in a multi-stage optimal reactive power flow (MORPF) framework, solved by the nonlinear programming techniques via a rolling process. The voltage uncertainty caused by wind power forecasting errors is considered in the optimal......This paper proposes an automatic voltage control (AVC) system for power systems with limited continuous voltage control capability. The objective is to minimize the operational cost over a period, which consists of the power loss in the grid, the shunt switching cost, the transformer tap change...

  15. Equivalent realisation circuit for a class of non-ideal voltage-controlled memristors

    Directory of Open Access Journals (Sweden)

    Saihu Pan

    2015-12-01

    Full Text Available In this study, an equivalent realisation circuit with off-the-shelf components and devices is proposed, which can be used to equivalently implement a class of non-ideal voltage-controlled memristors. The mathematical models of the equivalent realisation circuit with three function arithmetic circuits are built and their fingerprints are analysed by the pinched hysteresis loops with bipolar periodic voltage stimuli. The numerical simulations are easily verified by experimental measurements, which indicate that when three function arithmetic circuits are linked, the equivalent realisation circuit can realise three non-ideal voltage-controlled memristors with different non-linearities.

  16. Multi-Period Optimization for Voltage Control System in Transmission Grids

    DEFF Research Database (Denmark)

    Qin, Nan; Chen, Si; Liu, Chengxi

    2015-01-01

    Automatic Voltage Control (AVC) systems maintain the voltage in an acceptable range and minimize the power loss of the grid by coordinately regulating the controllable components. Switchable shunts and tap-able transformers are expected to be operated as few times as possible. This paper proposes....... In the lower level, the optimization is focused on the correction of the voltage violations every single minute based on data from the measurements and state estimation. The presented case study shows that the multi-period optimization in the upper level of AVC system can reduce adjustment times...

  17. Reactive Power Sharing and Voltage Harmonic Distortion Compensation of Droop Controlled Single Phase Islanded Microgrids

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2014-01-01

    When paralleling multiple inverters that are capable of operating as an island, the inverters typically employ the droop control scheme. Traditional droop control enables the decentralized regulation of the local voltage and frequency of the microgrid by the inverters. The droop method also enables...... and reduction of the voltage harmonic distortion at the point of common coupling (PCC). Experimental results were then presented to show the suitability of the proposed algorithms in achieving reactive power sharing and in improving the voltage harmonic distortion at the PCC....

  18. A Precise Robust Fuzzy Control of Robots Using Voltage Control Strategy

    Institute of Scientific and Technical Information of China (English)

    Mohammad Mehdi Fateh; Sara Fateh

    2013-01-01

    Fuzzy control of robot manipulators with a decentralized structure is facing a serious challenge.The state-space model of a robotic system including the robot manipulator and motors is in non-companion form,multivariable,highly nonlinear,and heavily coupled with a variable input gain matrix.Considering the problem,causes and solutions,we use voltage control strategy and convergence analysis to design a novel precise robust fuzzy control (PRFC) approach for electrically driven robot manipulators.The proposed fuzzy controller is Mamdani type and has a decentralized structure with guaranteed stability.In order to obtain a precise response,we regulate a fuzzy rule which governs the origin of the tracking space.The proposed design is verified by stability analysis.Simulations illustrate the superiority of the PRFC over a proprotional derivative like (PD-like) fuzzy controller applied on a selective compliant assembly robot arm (SCARA) driven by permanent magnet DC motors.

  19. Proportional integral plus multi-frequency resonant current controller for grid-connected voltage source converter under imbalanced and distorted supply voltage conditions

    Institute of Scientific and Technical Information of China (English)

    Jia-bing HU; Wei ZHANG; Hong-sheng WANG; Yi-kang HE; Lie XU

    2009-01-01

    This paper proposes a current control scheme for a grid-connected pulse width modulator (PWM) voltage source converter (GC-VSC) under imbalanced and distorted supply voltage conditions. The control scheme is implemented in the positive synchronously rotating reference frame and composed of a single proportional integral (PI) regulator and multi-frequency resonant controllers tuned at the frequencies of 2ω and 6ω, respectively. The experimental results, with the target of eliminating the active power oscillations and current harmonics on a prototype GC-VSC system, validate the feasibility of the proposed current control scheme during supply voltage imbalance and distortion.

  20. Voltage Stabilization of a Wind Turbine with STATCOM Using Intelligent Control Techniques

    Directory of Open Access Journals (Sweden)

    S. A. Gawish

    2016-03-01

    Full Text Available Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind System is investigated. The essential feature of the STATCOM is that it has the ability to absorb or inject fastly reactive power with power grid. Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the wind system at suddenly step up or down in wind speed is obtained with STATCOM. This paper describes a complete simulation of voltage regulation of a wind system using STATCOM. Conventional control technique as proportional plus integral controller , and intelligent techniques as FLC and ANFIS are used in this work. The control technique is performed using MATLAB package software. The dynamic response of uncontrolled system is also investigated under wide range of disturbances. The voltage regulation by using STATCOM whose output is varied so as to maintain or control output voltage in the system. The dynamic response of controlled system is shown and comparison between the uncontrolled system and the controlled system is described to assure the validity of the proposed controller. Also comparison between the proposed control methods scheme is presented. To validate the powerful of the STATCOM FACTS controllers, the studied power system is simulated and subjected to different severe disturbances. The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability and voltage.

  1. A Simple Voltage Controlled Oscillator Using Bootstrap Circuits and NOR-RS Flip Flop

    Science.gov (United States)

    Chaikla, Amphawan; Pongswatd, Sawai; Sasaki, Hirofumi; Fujimoto, Kuniaki; Yahara, Mitsutoshi

    This paper presents a simple and successful design for a voltage controlled oscillator. The proposed circuit is based on the use of two identical bootstrap circuits and a NOR-RS Flip Flop to generate wide-tunable sawtooth and square waves. Increasing control voltage linearly increases the output oscillation frequency. Experimental results verifying the performances of the proposed circuit are in agreement with the calculated values.

  2. Fuzzy Algorithm for Supervisory Voltage/Frequency Control of a Self Excited Induction Generator

    Directory of Open Access Journals (Sweden)

    Hussein F. Soliman

    2006-01-01

    Full Text Available This paper presents the application of a Fuzzy Logic Controller (FLC to regulate the voltage of a Self Excited Induction Generator (SEIG driven by Wind Energy Conversion Schemes (WECS. The proposed FLC is used to tune the integral gain (KI of a Proportional plus Integral (PI controller. Two types of controls, for the generator and for the wind turbine, using a FLC algorithm, are introduced in this paper. The voltage control is performed to adapt the terminal voltage via self excitation. The frequency control is conducted to adjust the stator frequency through tuning the pitch angle of the WECS blades. Both controllers utilize the Fuzzy technique to enhance the overall dynamic performance.  The simulation result depicts a better dynamic response for the system under study during the starting period, and the load variation. The percentage overshoot, rising time and oscillation are better with the fuzzy controller than with the PI controller type. 

  3. A centralized control architecture for harmonic voltage suppression in islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2011-01-01

    This paper proposes a centralized control architecture for harmonic voltage suppression in islanded microgrids. The centralized selective harmonic compensator is developed in addition to the autonomous nonlinear load sharing loop in local controllers of inverter-interfaced Distributed Energy Reso...... transformation aided signal modulation method is integrated to the centralized control architecture. The operation principle and case studies based on computer simulations are presented in this paper and validate the proposed control architecture.......This paper proposes a centralized control architecture for harmonic voltage suppression in islanded microgrids. The centralized selective harmonic compensator is developed in addition to the autonomous nonlinear load sharing loop in local controllers of inverter-interfaced Distributed Energy...

  4. Direct-detect Type Residual Charge Method with Short-term Voltage Up-down for Water Tree Deterioration Diagnosis in XLPE Cable

    Science.gov (United States)

    Ootaka, Iwao; Aoki, Masaru; Togashi, Hirotaka; Tsujimoto, Tomiyuki; Nakade, Masahiko

    Water tree is one of the unique type of deterioration in XLPE cable, which is the primary cause of aging breakdown. Water tree, which bridges between conductor and shield, can be detected easily, such as DC leakage current method. However, 22kV class or above XLPE cable, most of breakdown occurs before water tree bridges, and there used to be no effective method for detecting non-bridged water tree. In this paper, we've found residual charge in harmful water tree relaxes quickly with AC voltage application. To detect this type of residual charge, we've developed new diagnosis method with “direct-detect type residual charge method" and “short-term voltage up-down method". This new method found to be very effective for diagnosing over 22kV class XLPE cable lines.

  5. What Controls the Rate of Ultrafast Charge Transfer and Charge Separation Efficiency in Organic Photovoltaic Blends.

    Science.gov (United States)

    Jakowetz, Andreas C; Böhm, Marcus L; Zhang, Jiangbin; Sadhanala, Aditya; Huettner, Sven; Bakulin, Artem A; Rao, Akshay; Friend, Richard H

    2016-09-14

    In solar energy harvesting devices based on molecular semiconductors, such as organic photovoltaics (OPVs) and artificial photosynthetic systems, Frenkel excitons must be dissociated via charge transfer at heterojunctions to yield free charges. What controls the rate and efficiency of charge transfer and charge separation is an important question, as it determines the overall power conversion efficiency (PCE) of these systems. In bulk heterojunctions between polymer donor and fullerene acceptors, which provide a model system to understand the fundamental dynamics of electron transfer in molecular systems, it has been established that the first step of photoinduced electron transfer can be fast, of order 100 fs. But here we report the first study which correlates differences in the electron transfer rate with electronic structure and morphology, achieved with sub-20 fs time resolution pump-probe spectroscopy. We vary both the fullerene substitution and donor/fullerene ratio which allow us to control both aggregate size and the energetic driving force for charge transfer. We observe a range of electron transfer times from polymer to fullerene, from 240 fs to as short as 37 fs. Using ultrafast electro-optical pump-push-photocurrent spectroscopy, we find the yield of free versus bound charges to be weakly dependent on the energetic driving force, but to be very strongly dependent on fullerene aggregate size and packing. Our results point toward the importance of state accessibility and charge delocalization and suggest that energetic offsets between donor and acceptor levels are not an important criterion for efficient charge generation. This provides design rules for next-generation materials to minimize losses related to driving energy and boost PCE.

  6. A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Xu, Fengda; Guo, Qinglai; Sun, Hongbin;

    2015-01-01

    to keep the voltage of the pilot bus tracking its set point considering the DC system’s transmission schedule change. The approach is inspired by model predictive control (MPC) to compensate for predictable voltage change affected by DC side transmission power flow and the potential capacitor switching...

  7. Voltage Control Scheme with Distributed Generation and Grid Connected Converter in a DC Microgrid

    Directory of Open Access Journals (Sweden)

    Jong-Chan Choi

    2014-10-01

    Full Text Available Direct Current (DC microgrids are expected to become larger due to the rapid growth of DC energy sources and power loads. As the scale of the system expends, the importance of voltage control will be increased to operate power systems stably. Many studies have been performed on voltage control methods in a DC microgrid, but most of them focused only on a small scale microgrid, such as a building microgrid. Therefore, a new control method is needed for a middle or large scale DC microgrid. This paper analyzes voltage drop problems in a large DC microgrid and proposes a cooperative voltage control scheme with a distributed generator (DG and a grid connected converter (GCC. For the voltage control with DGs, their location and capacity should be considered for economic operation in the systems. Accordingly, an optimal DG allocation algorithm is proposed to minimize the capacity of a DG for voltage control in DC microgrids. The proposed methods are verified with typical load types by a simulation using MATLAB and PSCAD/EMTDC.

  8. Comparison of control strategies for DFIG under symmetrical grid voltage dips

    DEFF Research Database (Denmark)

    Chen, Wenjie; Xu, Dehong; Chen, Min;

    2013-01-01

    This paper presents a series of current control strategies for the DFIG under symmetrical grid voltage dips. The controllable range, the damping time constant of the stator natural flux and the torque fluctuations of six control strategies are analyzed and compared. The control strategies which...

  9. DC-link Voltage Coordinative-Proportional Control in Cascaded Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Deng, Fujin

    2015-01-01

    PI controllers are frequently implemented in cascaded converter system to control the DC-link voltage, because they can achieve zero steady state error. However the PI controller adds a pole at the origin point and a zero on the left half plane, and it increases the control system type number, an...

  10. Development and Application of a Wireless Sensor for Space Charge Density Measurement in an Ultra-High-Voltage, Direct-Current Environment.

    Science.gov (United States)

    Xin, Encheng; Ju, Yong; Yuan, Haiwen

    2016-10-20

    A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected with space charge density sensors and a base station. The space charge density sensor based on atmospheric ion counter method is elaborated and developed, and the ARM microprocessor and Zigbee radio frequency module are applied. The wireless network communication quality and the relationship between energy consumption and transmission distance in the complicated electromagnetic environment is tested. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the UHVDC transmission lines and can accurately measure the space charge density.

  11. Effect of Fe{sub 3}O{sub 4} nanoparticles on space charge distribution in propylene carbonate under impulse voltage

    Energy Technology Data Exchange (ETDEWEB)

    Sima, Wenxia, E-mail: cqsmwx@cqu.edu.cn; Song, He; Yang, Qing; Guo, Hongda; Chen, Qiulin [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Shapingba, Chongqing 400044 (China)

    2015-12-15

    Addition of nanoparticles of the ferromagnetic material Fe{sub 3}O{sub 4} can increase the positive impulse breakdown voltage of propylene carbonate by 11.65%. To further investigate the effect of ferromagnetic nanoparticles on the space charge distribution in the discharge process, the present work set up a Kerr electro-optic field mapping measurement system using an array photodetector to carry out time-continuous measurement of the electric field and space charge distribution in propylene carbonate before and after modification. Test results show that fast electrons can be captured by Fe{sub 3}O{sub 4} nanoparticles and converted into relatively slow, negatively charged particles, inhibiting the generation and transportation of the space charge, especially the negative space charge.

  12. Hierarchical Control Scheme for Improving Transient Voltage Recovery of a DFIG-Based WPP

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinho; Muljadi, Eduard; Kang, Yong Cheol

    2015-06-05

    Modern grid codes require that wind power plants (WPPs) inject reactive power according to the voltage dip at a point of interconnection (POI). This requirement helps to support a POI voltage during a fault. However, if a fault is cleared, the POI and wind turbine generator (WTG) voltages are likely to exceed acceptable levels unless the WPP reduces the injected reactive power quickly. This might deteriorate the stability of a grid by allowing the disconnection of WTGs to avoid any damage. This paper proposes a hierarchical control scheme of a doubly-fed induction generator (DFIG)-based WPP. The proposed scheme aims to improve the reactive power injecting capability during the fault and suppress the overvoltage after the fault clearance. To achieve the former, an adaptive reactive power-to-voltage scheme is implemented in each DFIG controller so that a DFIG with a larger reactive power capability will inject more reactive power. To achieve the latter, a washout filter is used to capture a high frequency component contained in the WPP voltage, which is used to remove the accumulated values in the proportional-integral controllers. Test results indicate that the scheme successfully supports the grid voltage during the fault, and recovers WPP voltages without exceeding the limit after the fault clearance.

  13. Modeling of the voltage-controlled friction effect

    Institute of Scientific and Technical Information of China (English)

    孟永钢; 蒋洪军; 常秋英; 黄柏林

    2002-01-01

    A phenomenological model of the dependence of friction coefficient on external voltage is proposed based on experimental results of friction and electric current of three different trbopairs, Si3N4-ball/steel-disc, Si3N4-ball/brass-disc and SiO2-ball/steel-disc, lubricated with zinc strearate suspension. It was found that the variation of friction coefficient correlates with the variation of electric current for all of the three tribopairs. The change in electric current is considered to be caused by the rate of electrochemical reactions occurring on the rubbing surface. By taking the electrochemical reaction into account in the total energy consumption, an expression for describing the relationship between the rates of friction coefficient and electric current is derived, and the constants included in the expression are determined through curve fitting of experimental data.

  14. Voltage-controlled metal binding on polyelectrolyte-functionalized nanopores.

    Science.gov (United States)

    Actis, Paolo; Vilozny, Boaz; Seger, R Adam; Li, Xiang; Jejelowo, Olufisayo; Rinaudo, Marguerite; Pourmand, Nader

    2011-05-17

    Most of the research in the field of nanopore-based platforms is focused on monitoring ion currents and forces as individual molecules translocate through the nanopore. Molecular gating, however, can occur when target analytes interact with receptors appended to the nanopore surface. Here we show that a solid state nanopore functionalized with polyelectrolytes can reversibly bind metal ions, resulting in a reversible, real-time signal that is concentration dependent. Functionalization of the sensor is based on electrostatic interactions, requires no covalent bond formation, and can be monitored in real time. Furthermore, we demonstrate how the applied voltage can be employed to tune the binding properties of the sensor. The sensor has wide-ranging applications and, its simplest incarnation can be used to study binding thermodynamics using purely electrical measurements with no need for labeling.

  15. Neutralization of Gating Charges in Domain II of the Sodium Channel α Subunit Enhances Voltage-Sensor Trapping by a β-Scorpion Toxin

    Science.gov (United States)

    Cestèle, Sandrine; Scheuer, Todd; Mantegazza, Massimo; Rochat, Hervé; Catterall, William A.

    2001-01-01

    β-Scorpion toxins shift the voltage dependence of activation of sodium channels to more negative membrane potentials, but only after a strong depolarizing prepulse to fully activate the channels. Their receptor site includes the S3–S4 loop at the extracellular end of the S4 voltage sensor in domain II of the α subunit. Here, we probe the role of gating charges in the IIS4 segment in β-scorpion toxin action by mutagenesis and functional analysis of the resulting mutant sodium channels. Neutralization of the positively charged amino acid residues in the IIS4 segment by mutation to glutamine shifts the voltage dependence of channel activation to more positive membrane potentials and reduces the steepness of voltage-dependent gating, which is consistent with the presumed role of these residues as gating charges. Surprisingly, neutralization of the gating charges at the outer end of the IIS4 segment by the mutations R850Q, R850C, R853Q, and R853C markedly enhances β-scorpion toxin action, whereas mutations R856Q, K859Q, and K862Q have no effect. In contrast to wild-type, the β-scorpion toxin Css IV causes a negative shift of the voltage dependence of activation of mutants R853Q and R853C without a depolarizing prepulse at holding potentials from −80 to −140 mV. Reaction of mutant R853C with 2-aminoethyl methanethiosulfonate causes a positive shift of the voltage dependence of activation and restores the requirement for a depolarizing prepulse for Css IV action. Enhancement of sodium channel activation by Css IV causes large tail currents upon repolarization, indicating slowed deactivation of the IIS4 voltage sensor by the bound toxin. Our results are consistent with a voltage-sensor–trapping model in which the β-scorpion toxin traps the IIS4 voltage sensor in its activated position as it moves outward in response to depolarization and holds it there, slowing its inward movement on deactivation and enhancing subsequent channel activation. Evidently

  16. Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management

    Directory of Open Access Journals (Sweden)

    WLODARCZYK, P.

    2015-02-01

    Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.

  17. Improved direct power control of a grid-connected voltage source converter during network unbalance

    Institute of Scientific and Technical Information of China (English)

    Peng ZHOU; Wei ZHANG; Yi-kang HE; Rong ZENG

    2010-01-01

    This paper deals with an improved direct power control(DPC)strategy for the pulse width modulation(PWM)voltage source converter(VSC)under unbalanced grid voltage conditions.In order to provide enhanced control performance for the VSC,the resonant controllers tuned at the double grid frequency are applied in the DPC design to eliminate the power pulsations and dc link voltage ripples produced by the transient unbalanced grid faults.In this way,the output power and dc link voltage of the VSC can be directly regulated without positive and negative sequential decomposition.As a result,and as has been verified by experiment,the proposed method can provide fast dynamic response with easy implementation.

  18. Variable Voltage Source Inverter with controlled frequency spectrum based on Random Pulse Width Modulation

    Directory of Open Access Journals (Sweden)

    Muhammad Farrukh Yaqub

    2012-01-01

    Full Text Available This paper presents a new method for single phase variable voltage inverter based on Random Pulse Width Modulation. In Random Pulse Width Modulation based inverter, the frequency spectrum of the output current and voltage waveforms becomes continuous because of the randomization of the switching function of the devices controlling the output voltages. This paper establishes a theory that if the distributions of the random numbers generated by the random source are kept within certain limit with respect to the peak value of reference sinusoidal waveform, the frequency spectrum can be controlled. On the basis of the results, a novel drive using variable tap changing transformer (optional and adaptive random number generator, to control the ratio between the numbers generated by the random source and the reference waveform has been suggested that will guarantee a better power quality profile for a broad range of output voltages.

  19. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc......-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design...... guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc–ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five...

  20. The free energy barrier for arginine gating charge translation is altered by mutations in the voltage sensor domain.

    Directory of Open Access Journals (Sweden)

    Christine S Schwaiger

    Full Text Available The gating of voltage-gated ion channels is controlled by the arginine-rich S4 helix of the voltage-sensor domain moving in response to an external potential. Recent studies have suggested that S4 moves in three to four steps to open the conducting pore, thus visiting several intermediate conformations during gating. However, the exact conformational changes are not known in detail. For instance, it has been suggested that there is a local rotation in the helix corresponding to short segments of a 3(10-helix moving along S4 during opening and closing. Here, we have explored the energetics of the transition between the fully open state (based on the X-ray structure and the first intermediate state towards channel closing (C1, modeled from experimental constraints. We show that conformations within 3 Å of the X-ray structure are obtained in simulations starting from the C1 model, and directly observe the previously suggested sliding 3(10-helix region in S4. Through systematic free energy calculations, we show that the C1 state is a stable intermediate conformation and determine free energy profiles for moving between the states without constraints. Mutations indicate several residues in a narrow hydrophobic band in the voltage sensor contribute to the barrier between the open and C1 states, with F233 in the S2 helix having the largest influence. Substitution for smaller amino acids reduces the transition cost, while introduction of a larger ring increases it, largely confirming experimental activation shift results. There is a systematic correlation between the local aromatic ring rotation, the arginine barrier crossing, and the corresponding relative free energy. In particular, it appears to be more advantageous for the F233 side chain to rotate towards the extracellular side when arginines cross the hydrophobic region.

  1. Persistent photocurrent (PPC) in solution-processed organic thin film transistors: Mechanisms of gate voltage control

    Science.gov (United States)

    Singh, Subhash; Mohapatra, Y. N.

    2016-07-01

    There is a growing need to understand mechanisms of photoresponse in devices based on organic semiconductor thin films and interfaces. The phenomenon of persistent photocurrent (PPC) has been systematically investigated in solution processed TIPS-Pentacene based organic thin film transistors (OTFTs) as an important example of an organic semiconductor material system. With increasing light intensity from dark to 385 mW/cm2, there is a significant shift in threshold voltage (VTh) while the filed-effect mobility remains unchanged. The OTFT shows large photoresponse under white light illumination due to exponential tail states with characteristic energy parameter of 86 meV. The photo-induced current is observed to persist even for several hours after turning the light off. To investigate the origin of PPC, its quenching mechanism is investigated by a variety of methods involving a combination of gate bias, illumination and temperature. We show that a coherent model of trap-charge induced carrier concentration is able to account for the quenching behavior. Analysis of isothermal transients using time-analyzed transient spectroscopy shows that the emission rates are activated and are also field enhanced due to Poole-Frankel effect. The results shed light on the nature, origin, and energetic distribution of the traps controlling PPC in solution processed organic semiconductors and their interfaces.

  2. A dual-mode phase-shift modulation control scheme for voltage multiplier based X-ray power supply

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, S [School of Electrical and Electronics Engineering, University Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Besar, R; Venkataseshaiah, C, E-mail: shahidsidu@hotmail.co [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)

    2010-05-15

    This paper proposes a dual-mode phase-shift modulation control scheme for series resonant inverter fed voltage multiplier (VM) based X-ray power supply. In this control scheme the outputs voltage of two parallel connected series resonant inverters are mixed before supplying to VM circuit. The output voltage of the power supply is controlled by varying the phase-shift between the output voltages of two inverters. In order to achieve quick rise of output voltage, the power supply is started with zero phase-shift and as the output voltage reaches 90% of the target voltage, the phase-shift is increased to a value which corresponds to target output voltage to prevent overshoot. The proposed control scheme has been shown to have good performance. Experimental results based on the scaled-down laboratory prototype are presented to validate the effectiveness of proposed dual-mode phase shift modulation control scheme.

  3. Controlled charge exchange between alkaline earth metals and their ions

    Science.gov (United States)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  4. Suppression of surface charge accumulation on Al{sub 2}O{sub 3}-filled epoxy resin insulator under dc voltage by direct fluorination

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boya; Zhang, Guixin, E-mail: guixin@mail.tsinghua.edu.cn; Li, Chuanyang; He, Jinliang [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Qiang [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); School of Mechatronic Engineering, Beijing Institute of Technology, Beijing 100081 (China); An, Zhenlian [Department of Electrical Engineering, Tongji University, Shanghai 201804 (China)

    2015-12-15

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al{sub 2}O{sub 3}-filled epoxy resin were surface fluorinated using a F{sub 2}/N{sub 2} mixture (12.5% F{sub 2}) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  5. Charge carrier dynamics investigation of CuInS2 quantum dots films using injected charge extraction by linearly increasing voltage (i-CELIV): the role of ZnS Shell

    Science.gov (United States)

    Bi, Ke; Sui, Ning; Zhang, Liquan; Wang, Yinghui; Liu, Qinghui; Tan, Mingrui; Zhou, Qiang; Zhang, Hanzhuang

    2016-12-01

    The role of ZnS shell on the photo-physical properties within CuInS2/ZnS quantum dots (QDs) is carefully studied in optoelectronic devices. Linearly increasing voltage technique has been employed to investigate the charge carrier dynamics of both CuInS2 and CuInS2/ZnS QDs films. This study shows that charge carriers follow a similar behavior of monomolecular recombination in this film, with their charge transfer rate correlates to the increase of applied voltage. It turns out that the ZnS shell could affect the carrier diffusion process through depressing the trapping states and would build up a potential barrier.

  6. Clustered PV Inverters in LV Networks: An Overview of Impacts and Comparison of Voltage Control Strategies

    DEFF Research Database (Denmark)

    Demirok, Erhan; Sera, Dezso; Teodorescu, Remus;

    2009-01-01

    and power quality must be maintained or improved by adding cooperative control features to the grid-connected inverters. This paper first gives an overview of bilateral impacts between multiple distributed generations (DG) and grid. Regarding of these impacts, recent advances in static grid voltage support......High penetration of photovoltaic (PV) inverters in low voltage (LV) distribution network challenges the voltage stability due to interaction between multiple inverters and grid. As the main objective is to provide more power injection from VSC-based PV inverters, grid stability, reliability...

  7. Voltage-controlled accommodating IOL system using an ion polymer metal composite actuator.

    Science.gov (United States)

    Horiuchi, Tetsuya; Mihashi, Toshifumi; Fujikado, Takashi; Oshika, Tetsuro; Asaka, Kinji

    2016-10-03

    Surgeons treat cataracts by replacing the clouded lens with an intraocular lens (IOL), but patients are required to wear reading glasses for tasks requiring near vision. We suggest a new voltage-controlled accommodating IOL made of an ionic polymer metal composite (IPMC) actuator to change focus. An in vitro experiment was conducted where an actuator was placed inside the eye and moved with applied voltage. The lens attached to the actuator was deformed by its movement to change the patient's focus. The results showed that this system can accommodate a change of approximately 0.8 diopters under an applied voltage of ± 1.3 V.

  8. Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Silva, Filipe Faria Da; Bak, Claus Leth

    2014-01-01

    regulation. The proposed scheme demonstrates remarkable improvement transient state of both voltage and frequency profiles in comparison with conventional LFC designs provided by Central Power Plants (CPP) or Wind Power Plants (WPP). Numerical simulations carried out in DigSilent Power- Factory confirm......, sufficient reserve capacity should be procured. This paper addresses the Load-Frequency Control (LFC) scheme offered by VSWT. Feedback loop of locally measured voltage and frequency data is employed to improve transient and permanent response to achieve faster and more efficient LFC action and voltage...

  9. Extra-High-Voltage DC-DC Boost Converters Topology with Simple Control Strategy

    Directory of Open Access Journals (Sweden)

    K. Rajambal

    2009-01-01

    Full Text Available This paper presents the topology of operating DC-DC buck converter in boost mode for extra-high-voltage applications. Traditional DC-DC boost converters are used in high-voltage applications, but they are not economical due to the limited output voltage, efficiency and they require two sensors with complex control algorithm. Moreover, due to the effect of parasitic elements the output voltage and power transfer efficiency of DC-DC converters are limited. These limitations are overcome by using the voltage lift technique, opens a good way to improve the performance characteristics of DC-DC converter. The technique is applied to DC-DC converter and a simplified control algorithm in this paper. The performance of the controller is studied for both line and load disturbances. These converters perform positive DC-DC voltage increasing conversion with high power density, high efficiency, low cost in simple structure, small ripples, and wide range of control. Simulation results along theoretical analysis are provided to verify its performance.

  10. Robust Broadcast-Communication Control of Electric Vehicle Charging

    CERN Document Server

    Turitsyn, Konstantin; Backhaus, Scott; Chertkov, Misha

    2010-01-01

    The anticipated increase in the number of plug-in electric vehicles (EV) will put additional strain on electrical distribution circuits. Many control schemes have been proposed to control EV charging. Here, we develop control algorithms based on randomized EV charging start times and simple one-way broadcast communication allowing for a time delay between communication events. Using arguments from queuing theory and statistical analysis, we seek to maximize the utilization of excess distribution circuit capacity while keeping the probability of a circuit overload negligible.

  11. Robust broadcast-communication control of electric vehicle charging

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Sulc, Petr [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory

    2010-01-01

    The anticipated increase in the number of plug-in electric vehicles (EV) will put additional strain on electrical distribution circuits. Many control schemes have been proposed to control EV charging. Here, we develop control algorithms based on randomized EV charging start times and simple one-way broadcast communication allowing for a time delay between communication events. Using arguments from queuing theory and statistical analysis, we seek to maximize the utilization of excess distribution circuit capacity while keeping the probability of a circuit overload negligible.

  12. Negative Sequence Droop Method based Hierarchical Control for Low Voltage Ride-Through in Grid-Interactive Microgrids

    DEFF Research Database (Denmark)

    Zhao, Xin; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez

    2015-01-01

    . In this paper, a voltage support strategy based on negative sequence droop control, which regulate the positive/negative sequence active and reactive power flow by means of sending proper voltage reference to the inner control loop, is proposed for the grid connected MGs to ride through voltage sags under...... complex line impedance conditions. In this case, the MGs should inject a certain amount of positive and negative sequence power to the grid so that the voltage quality at load side can be maintained at a satisfied level. A two layer hierarchical control strategy is proposed in this paper. The primary...... control loop consists of voltage and current inner loops, conventional droop control and virtual impedance loop while the secondary control loop is based on positive/negative sequence droop control which can achieve power injection under voltage sags. Experimental results with asymmetrical voltage sags...

  13. Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hunter; Sealy, Kylee Devro; Sharp, Bryan Thomas; Gilchrist, Aaron

    2016-01-26

    A method and apparatus for LCL resonant converter control utilizing Asymmetric Voltage Cancellation is described. The methods to determine the optimal trajectory of the control variables are discussed. Practical implementations of sensing load parameters are included. Simple PI, PID and fuzzy logic controllers are included with AVC for achieving good transient response characteristics with output current regulation.

  14. Assessment of distribution grid voltage control strategies in view of deployment

    DEFF Research Database (Denmark)

    Han, Xue; Kosek, Anna Magdalena; Bondy, Daniel Esteban Morales

    2014-01-01

    different capabilities of DERs and regulating devices to assist grid operation. However, very few of them have discussed the opportunities and barriers of deploying the control strategies in practice. This paper reviews some typical control solutions on providing voltage control services. Furthermore...

  15. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    Directory of Open Access Journals (Sweden)

    Seyed Mahyar Mehdizadeh Moghadam

    2014-07-01

    Full Text Available In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast control system is impossible therefore a nonlinear feedforward control loop is used to faster the control system performance. Linear control system is used to control the AC-side in synchrony reference frame such that the AC voltage control system regulates the output voltage by means of modulation index regulation. The proposed control system performance is investigated by simulation in MATLAB/Simulink

  16. Generic inertia emulation controller for multi-terminal voltage-source-converter high voltage direct current systems

    DEFF Research Database (Denmark)

    Zhu, Jiebei; Guerrero, Josep M.; Hung, William;

    2014-01-01

    within a safe and pre-defined range. A theoretical treatment of the INEC algorithm and its implementation and integration within a conventional VSC control system are presented, and the impact on the total DC capacitance required within the MTDC network to ensure that DC voltages vary within...... an acceptable range are discussed. The proposed INEC scheme is validated using a Matlab/Simulink model under various changes in demand and in response to AC network faults. The model incorporates a multi-machine AC power system connected to a MTDC transmission system with multiple converter-interfaced nodes....... The effectiveness of the INEC in damping post-fault oscillations and in enhancing AC system frequency stability is also investigated. The system is shown to perform well and is attractive for providing a stable MTDC system that is capable of providing valuable support to the connected AC systems....

  17. Self-focusing effect in voltage-controlled PPLN waveguide arrays

    Institute of Scientific and Technical Information of China (English)

    Yong Yang; Xuewei Deng; Huiying Lao; Xianfeng Chen

    2011-01-01

    @@ Self-focusing effect via Kerr nonlinearity is observed in periodically poled lithium niobate (PPLN) waveguide arrays formed by electro-optic effect. Voltage-control method is demonstrated to control the focusing and diffraction of light. Theoretical simulation results show good agreement with experimental results.%Self-focusing effect via Kerr nonlinearity is observed in periodically poled lithium niobate (PPLN) waveguide arrays formed by electro-optic effect. Voltage-control method is demonstrated to control the focusing and diffraction of light. Theoretical simulation results show good agreement with experimental results.

  18. Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

    Directory of Open Access Journals (Sweden)

    Sreenivasappa Veeranna Bhupasandra

    2010-01-01

    Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

  19. DC Voltage Control Strategy for CHB-STATCOM during Capacitive-Inductive Load Transition

    Directory of Open Access Journals (Sweden)

    Bo Zhao

    2012-11-01

    Full Text Available Fluctuation of DC capacitor voltage of CHC-STATCOM(Cascaded H-Bridge Converter Based STATCOM during capacitive-inductive load transition affects the dynamic response of the equipment and, with combination of other factors like of the switching devices, can degrade the stability of the equipment. This paper illustrates the cause ofthe voltage fluctuation and proposes a novel and practical control strategy to suppress it. A simulation was conducted to testify its effectiveness.

  20. Effects of Direct Torque Control Switching Strategies on Common Voltage and Bearing Current

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Sadeghzadeh

    2012-04-01

    Full Text Available Bearing current sininduction motorsare considered a sone of the most damaging factors. Induced shaft voltage through the parasitic capacitors cause this type of current. Inthispaper,given the increasing importance of direct torque control of induction motorin industry, various switching tables are assessed in order to ensure the lowest common voltage while maintaining the performance characteristics of the drive. Finally best switching table based on the minimum CMV, less torque rippleand better quality out put reference tracking is proposed.

  1. Formation of charged ferroelectric domain walls with controlled periodicity.

    Science.gov (United States)

    Bednyakov, Petr S; Sluka, Tomas; Tagantsev, Alexander K; Damjanovic, Dragan; Setter, Nava

    2015-10-30

    Charged domain walls in proper ferroelectrics were shown recently to possess metallic-like conductivity. Unlike conventional heterointerfaces, these walls can be displaced inside a dielectric by an electric field, which is of interest for future electronic circuitry. In addition, theory predicts that charged domain walls may influence the electromechanical response of ferroelectrics, with strong enhancement upon increased charged domain wall density. The existence of charged domain walls in proper ferroelectrics is disfavoured by their high formation energy and methods of their preparation in predefined patterns are unknown. Here we develop the theoretical background for the formation of charged domain walls in proper ferroelectrics using energy considerations and outline favourable conditions for their engineering. We experimentally demonstrate, in BaTiO3 single crystals the controlled build-up of high density charged domain wall patterns, down to a spacing of 7 μm with a predominant mixed electronic and ionic screening scenario, hinting to a possible exploitation of charged domain walls in agile electronics and sensing devices.

  2. Analysis of a Microgrid under Transient Conditions Using Voltage and Frequency Controller

    Directory of Open Access Journals (Sweden)

    Monika Jain

    2012-01-01

    Full Text Available This paper presents an investigation of voltage-and-frequency-(VF- based battery energy storage system (BESS controller used in micro grid for analyzing the optimum capability of plant. Microgrid is formed by using three hydropower plants feeding three-phase four-wire load. The proposed controller is used for load balancing, harmonic elimination, load leveling, and neutral current compensation. The proposed BESS controller permits the selection of an optimum voltage level of battery and allows independent current control of each phase. The main emphasis is given on maintaining constant voltage and frequency within the micro grid during transient conditions. Micro grid with power plant and its controller is modeled in MATLAB/Simulink using Power System Blockset (PSB toolboxes.

  3. Disturbance Attenuation of DC Voltage Droop Control Structures in a Multi-Terminal HVDC Grid

    DEFF Research Database (Denmark)

    Thams, Florian; Chatzivasileiadis, Spyros; Prieto-Araujo, Eduardo

    2017-01-01

    of the disturbance rejection of these droop control structures. The approach is based on multi-variable frequency response analysis where both ac and dc grid dynamics are incorporated. In particular, the amplification of dc voltage oscillations due to wind power variations is analyzed using singular value analysis......DC voltage droop control is seen as the preferred control structure for primary voltage control of future multiterminal HVDC systems. Different droop control structures have been proposed in literature which can be classified in eight categories. This paper contributes to an analysis....... Further, the impact of dc cable modeling on the results is discussed. In addition, it is shown that the maximum singular value limits, frequently used in literature for MIMO-analysis, are not sufficient to prove that the impact of certain disturbances on analyzed outputs is within a certain boundary...

  4. Robust Frequency and Voltage Stability Control Strategy for Standalone AC/DC Hybrid Microgrid

    Directory of Open Access Journals (Sweden)

    Furqan Asghar

    2017-05-01

    Full Text Available The microgrid (MG concept is attracting considerable attention as a solution to energy deficiencies, especially in remote areas, but the intermittent nature of renewable sources and varying loads cause many control problems and thereby affect the quality of power within a microgrid operating in standalone mode. This might cause large frequency and voltage deviations in the system due to unpredictable output power fluctuations. Furthermore, without any main grid support, it is more complex to control and manage the system. In past, droop control and various other coordination control strategies have been presented to stabilize the microgrid frequency and voltages, but in order to utilize the available resources up to their maximum capacity in a positive way, new and robust control mechanisms are required. In this paper, a standalone microgrid is presented, which integrates renewable energy-based distributed generations and local loads. A fuzzy logic-based intelligent control technique is proposed to maintain the frequency and DC (direct current-link voltage stability for sudden changes in load or generation power. Also from a frequency control perspective, a battery energy storage system (BESS is suggested as a replacement for a synchronous generator to stabilize the nominal system frequency as a synchronous generator is unable to operate at its maximum efficiency while being controlled for stabilization purposes. Likewise, a super capacitor (SC and BESS is used to stabilize DC bus voltages even though maximum possible energy is being extracted from renewable generated sources using maximum power point tracking. This newly proposed control method proves to be effective by reducing transient time, minimizing the frequency deviations, maintaining voltages even though maximum power point tracking is working and preventing generators from exceeding their power ratings during disturbances. However, due to the BESS limited capacity, load switching

  5. Voltage Control for Unbalanced Low Voltage Grids Using a Decoupled-Phase On-Load Tap-Changer Transformer and Photovoltaic Inverters

    OpenAIRE

    Zecchino, Antonio; Marinelli, Mattia; Hu, Junjie; Coppo, Massimiliano; Turri, Roberto

    2015-01-01

    This paper presents modeling and analysis of the potential benefits of joint actions of a MV/LV three-phase power distribution transformer with independent on-load tap-changer control on each phase and photovoltaic inverters provided with reactive power control capability, in terms of accommodating more renewable generations in the LV grid. The potential benefits are investigated in terms of voltage unbalance reduction and local voltage regulation. 24-hours root-mean-square dynamics simulatio...

  6. Adaptive voltage control in power systems modeling, design and applications

    CERN Document Server

    Fusco, Giuseppe

    2006-01-01

    Large-scale power cuts in both North America and Europe emphasised the need to maintain an adequate supply of high-quality electricity. This book offers information on the relatively low-cost of doing so using self-regulating control mechanisms. It is of interest to the practising power/control engineer and to academics needing industrial inputs.

  7. SoC-Based Output Voltage Control for BESS with a Lithium-Ion Battery in a Stand-Alone DC Microgrid

    Directory of Open Access Journals (Sweden)

    Seung-Yeong Yu

    2016-11-01

    Full Text Available This paper proposes a new DC output voltage control for a battery energy storage system (BESS with a lithium-ion battery based on the state of charge (SoC. The proposed control scheme was verified through computer simulations for a typical stand-alone DC microgrid, which consists of a BESS, photovoltaic (PV panel, engine generator (EG, and DC load. A scaled hardware prototype for a stand-alone DC microgrid was set up in the lab, in which the proposed control scheme was loaded in a DSP controller. The experimental results were compared with the simulation results for performance verification. The proposed control scheme provides relatively lower variation of the DC grid voltage than the conventional droop control.

  8. Influence of Wind Plant Ancillary Voltage Control on System Small Signal Stability

    DEFF Research Database (Denmark)

    Su, Chi; Chen, Zhe

    2012-01-01

    As a common tendency, large-scale wind farms are increasingly connected to the transmission system of modern power grids. This introduces some new challenges to the connected power systems, and the transmission system operators (TSOs) have to put some new requirements as part of the grid codes...... on the integration of wind farms. One common requirement to wind farms is the function of system voltage control which can be implemented in the grid-side convertor controller of a variable speed wind turbine. This ancillary voltage control provided by wind farms could have some influence on the system small signal...... stability. This paper implements an ancillary voltage control strategy on a direct-drive-full-convertor-based wind farm and studies its influence on the damping ratio values of the dominant oscillation mode within the connected power system. All the calculations and simulations are conducted in DIg...

  9. Adaptive Hierarchical Voltage Control of a DFIG-Based Wind Power Plant for a Grid Fault

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinho; Muljadi, Eduard; Park, Jung-Wook; Kang, Yong Cheol

    2016-11-01

    This paper proposes an adaptive hierarchical voltage control scheme of a doubly-fed induction generator (DFIG)-based wind power plant (WPP) that can secure more reserve of reactive power (Q) in the WPP against a grid fault. To achieve this, each DFIG controller employs an adaptive reactive power to voltage (Q-V) characteristic. The proposed adaptive Q-V characteristic is temporally modified depending on the available Q capability of a DFIG; it is dependent on the distance from a DFIG to the point of common coupling (PCC). The proposed characteristic secures more Q reserve in the WPP than the fixed one. Furthermore, it allows DFIGs to promptly inject up to the Q limit, thereby improving the PCC voltage support. To avert an overvoltage after the fault clearance, washout filters are implemented in the WPP and DFIG controllers; they can prevent a surplus Q injection after the fault clearance by eliminating the accumulated values in the proportional-integral controllers of both controllers during the fault. Test results demonstrate that the scheme can improve the voltage support capability during the fault and suppress transient overvoltage after the fault clearance under scenarios of various system and fault conditions; therefore, it helps ensure grid resilience by supporting the voltage stability.

  10. Activate distributed energy resources' services: Hierarchical voltage controller as an application

    DEFF Research Database (Denmark)

    Han, Xue; Kosek, Anna Magdalena; Gehrke, Oliver

    2014-01-01

    The flexibilities from controllable distributed energy resources (DERs) offer the opportunities to mitigate some of the operation problems in the power distribution grid. The provision of system services requires the aggregation and coordination of their flexibilities, in order to obtain the flex...... the efficient aggregation and dispatch, and it simplifies the optimization complexity; the involvement of DER flexibilities in voltage services can significantly improve the voltage quality and reduce the grid power loss without additional regulating devices....... the flexible capacity of large scale. In this paper, a hierarchical controller is presented to activate the aggregation, and tries to obtain a global optimum of the grid operation. A distribution grid with large penetration of highly varying generation or load is under the risk that the voltage quality...... delivered to the end users is very poor. Hence, a coordinated voltage control function is investigated given such control hierarchy utilizing the flexibilities from the DER units to obtain an optimal voltage profile along the distribution feeder. The results are two folded: the controller enables...

  11. 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.

  12. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    Science.gov (United States)

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-08

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  13. Effect of strain on voltage-controlled magnetism in BiFeO₃-based heterostructures.

    Science.gov (United States)

    Wang, J J; Hu, J M; Yang, T N; Feng, M; Zhang, J X; Chen, L Q; Nan, C W

    2014-04-01

    Voltage-modulated magnetism in magnetic/BiFeO3 heterostructures can be driven by a combination of the intrinsic ferroelectric-antiferromagnetic coupling in BiFeO3 and the antiferromagnetic-ferromagnetic exchange interaction across the heterointerface. However, ferroelectric BiFeO3 film is also ferroelastic, thus it is possible to generate voltage-induced strain in BiFeO3 that could be applied onto the magnetic layer across the heterointerface and modulate magnetism through magnetoelastic coupling. Here, we investigated, using phase-field simulations, the role of strain in voltage-controlled magnetism for these BiFeO3-based heterostructures. It is predicted, under certain condition, coexistence of strain and exchange interaction will result in a pure voltage-driven 180° magnetization reversal in BiFeO3-based heterostructures.

  14. Optimized Control Strategy for a Medium-Voltage DVR-Theoretical Investigations and Experimental Results

    DEFF Research Database (Denmark)

    Meyer, Christoph; De Doncker, Rik W.; Li, Yun Wei;

    2008-01-01

    a small fraction of the energy stored in the DC-link capacitor is used, which makes it impractical for DVRs to compensate relatively long voltage sags. Present control strategies are only able to minimize the distortions at the load or to allow a better utilization of the storage system by minimizing......Most power quality problems in distribution systems are related to voltage sags. Therefore, different solutions have been examined to compensate these sags to avoid production losses at sensitive loads. Dynamic voltage restorers (DVRs) have been proposed to provide higher power quality. Currently......, a system wide integration of DVRs is hampered because of their high cost, in particular, due to the expensive DC-link energy storage devices. The cost of these DC-link capacitors remains high because the DVR requires a minimum DC-link voltage to be able to operate and to compensate a sag. As a result, only...

  15. Voltage controlled modification of flux closure domains in planar magnetic structures for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Parkes, D. E.; Beardsley, R.; Edmonds, K. W.; Campion, R. P.; Gallagher, B. L.; Rushforth, A. W., E-mail: Stuart.Cavill@york.ac.uk, E-mail: Andrew.Rushforth@nottingham.ac.uk [School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Bowe, S. [School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Isakov, I.; Warburton, P. A. [London Centre of Nanotechnology, University College London, London WC1H 0AH (United Kingdom); Cavill, S. A., E-mail: Stuart.Cavill@york.ac.uk, E-mail: Andrew.Rushforth@nottingham.ac.uk [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2014-08-11

    Voltage controlled modification of the magnetocrystalline anisotropy in a hybrid piezoelectric/ferromagnet device has been studied using Photoemission Electron Microscopy with X-ray magnetic circular dichroism as the contrast mechanism. The experimental results demonstrate that the large magnetostriction of the epitaxial Fe{sub 81}Ga{sub 19} layer enables significant modification of the domain pattern in laterally confined disc structures. In addition, micromagnetic simulations demonstrate that the strain induced modification of the magnetic anisotropy allows for voltage tuneability of the natural resonance of both the confined spin wave modes and the vortex motion. These results demonstrate the possibility for using voltage induced strain in low-power voltage tuneable magnetic microwave oscillators.

  16. Voltage regulation in LV grids by coordinated volt-var control strategies

    DEFF Research Database (Denmark)

    Juamperez Goñi, Miguel Angel; Yang, Guangya; Kjær, Søren Bækhøj

    2014-01-01

    in terms of network power losses and voltage level along the feeder. As a practical implementation, a reconfigurable hardware is used for developing a testing platform based on real-time measurements to regulate the reactive power level. The proposed testing platform has been developed within PVNET......The increasing penetration level of photovoltaic (PV) power generation in low voltage (LV) networks results in voltage rise issues, particularly at the end of the feeders. In order to mitigate this problem, several strategies, such as grid reinforcement, transformer tap change, demand......-side management, active power curtailment, and reactive power optimization methods, show their contribution to voltage support, yet still limited. This paper proposes a coordinated volt-var control architecture between the LV distribution transformer and solar inverters to optimize the PV power penetration level...

  17. Current-voltage characteristics and charge DLTS spectra of proton-bombarded Schottky diodes on semi-insulating GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Thurzo, I. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia)); Hrubcin, L. (Inst. of Electrical Engineering, Slovak Academy of Sciences, Bratislava (Slovakia)); Bartos, J. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia)); Pincik, E. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia))

    1993-10-01

    Changes in the current-voltage characteristics and charge DLTS spectra of Schottky diodes on semi-insulating GaAs after irradiation by protons at different energies and doses are presented and discussed. Apart from a progressive degradation of the Schottky barriers with enhanced proton energy and dose, there is a threshold, positioned between 10[sup 14] and 10[sup 15] protons/cm[sup 2], for observing trap-limited transients. (orig.)

  18. Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands

    KAUST Repository

    Ndjawa, Guy O. Ngongang

    2017-01-16

    In organic solar cells (OSCs), the energy of the charge-transfer (CT) complexes at the donor-acceptor interface, E , determines the maximum open-circuit voltage (V ). The coexistence of phases with different degrees of order in the donor or the acceptor, as in blends of semi-crystalline donors and fullerenes in bulk heterojunction layers, influences the distribution of CT states and the V enormously. Yet, the question of how structural heterogeneities alter CT states and the V is seldom addressed systematically. In this work, we combine experimental measurements of vacuum-deposited rubrene/C bilayer OSCs, with varying microstructure and texture, with density functional theory calculations to determine how relative molecular orientations and extents of structural order influence E and V . We find that varying the microstructure of rubrene gives rise to CT bands with varying energies. The CT band that originates from crystalline rubrene lies up to ≈0.4 eV lower in energy compared to the one that arises from amorphous rubrene. These low-lying CT states contribute strongly to V losses and result mainly from hole delocalization in aggregated rubrene. This work points to the importance of realizing interfacial structural control that prevents the formation of low E configurations and maximizes V .

  19. Design and power management of an offshore medium voltage DC microgrid realized through high voltage power electronics technologies and control

    Science.gov (United States)

    Grainger, Brandon Michael

    The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is

  20. Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

    Science.gov (United States)

    Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya

    2013-05-01

    Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

  1. Design and Evaluation of Autonomous Hybrid Frequency-Voltage Sensitive Load Controller

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Sossan, Fabrizio;

    2013-01-01

    The paper introduces an algorithm for control of autonomous loads without digital communication interfaces to provide both frequency regulation and voltage regulation services. This hybrid controller can be used to enhance frequency sensitive loads to mitigate line overload arising from reduced...

  2. A decentralized scalable approach to voltage control of DC islanded microgrids

    DEFF Research Database (Denmark)

    Tucci, Michele; Riverso, Stefano; Quintero, Juan Carlos Vasquez

    2016-01-01

    We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the point of common coupling of the corresponding DGU...

  3. A simple output voltage control scheme for single phase wavelet ...

    African Journals Online (AJOL)

    DR OKE

    carried out in this paper is to find a feasible solution to the magnitude control ... DOI: http://dx.doi.org/10.4314/ijest.v7i3.13S. 1. ..... research interest includes electric power quality, signal processing and machine learning applications to power ...

  4. A sensorless control method for capacitor voltage balance and circulating current suppression of modular multilevel converter

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang

    2015-01-01

    There are several problems in the Modular Multilevel Converter (MMC), such as the appearance of circulating current, capacitor voltage unbalance and the requirement for a high number of sensors. All these problems will decrease the reliability and raise the cost/uncertainty of using MMC solutions....... As a result, a sensorless control method is proposed in this paper, which targets to improve the performances of MMC in respect to the above mentioned disadvantages: To decrease the cost and simplify the physical implementation, a state observer is proposed and designed to estimate both the capacitor voltages...... and the circulating currents in order to replace the high numbers of sensors. Furthermore, a control method combining the circulating current suppression and the capacitor voltage balancing is conducted based on the proposed state observer. It is concluded that the proposed state observer and control method can...

  5. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2017-01-01

    This paper presents a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without using communication system. To perform the twofold objectives, a small signal model is first developed to reconstruct the system input...... performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides the expected reliability and flexibility for optimizing......-output relationship, which is evaluated through sensitivity analysis. A state estimator is then constructed to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive power sharing and system voltage restoration. And the dynamic...

  6. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2016-01-01

    The paper proposes a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without communication system. To realize the twofold objective, an improved small signal model is developed first to reconstruct the system input...... power sharing and system voltage restoration. And the dynamic performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides......-output relationship, where the relationship is evaluated with sensitivity analysis. A state estimator is then constructed based on the new input-output relationship in order to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive...

  7. Voltage Recovery of Dynamic Slip Control Wind Turbines with a STATCOM

    DEFF Research Database (Denmark)

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

    2005-01-01

    operating condition quickly for power system stability. This paper studies the voltage recovery of a dynamic slip and turbine pitch controlled wind turbine. A simulation model of a dynamic slip controlled wind turbine in PSCAD/EMTDC is presented, and the control schemes are described. The function......The fast development of wind power generation presents new requirements for the wind turbines integrated into the network. After the clearance of an external short-circuit fault, the voltage at the generator terminal needs to be re-established and the wind turbine should restore its normal...... of a STATCOM in re-establishing the system voltage after the clearance of an external short-circuit fault and restoring the normal operation of the wind turbine has been investigated....

  8. Dynamic control of a homogeneous charge compression ignition engine

    Science.gov (United States)

    Duffy, Kevin P.; Mehresh, Parag; Schuh, David; Kieser, Andrew J.; Hergart, Carl-Anders; Hardy, William L.; Rodman, Anthony; Liechty, Michael P.

    2008-06-03

    A homogenous charge compression ignition engine is operated by compressing a charge mixture of air, exhaust and fuel in a combustion chamber to an autoignition condition of the fuel. The engine may facilitate a transition from a first combination of speed and load to a second combination of speed and load by changing the charge mixture and compression ratio. This may be accomplished in a consecutive engine cycle by adjusting both a fuel injector control signal and a variable valve control signal away from a nominal variable valve control signal. Thereafter in one or more subsequent engine cycles, more sluggish adjustments are made to at least one of a geometric compression ratio control signal and an exhaust gas recirculation control signal to allow the variable valve control signal to be readjusted back toward its nominal variable valve control signal setting. By readjusting the variable valve control signal back toward its nominal setting, the engine will be ready for another transition to a new combination of engine speed and load.

  9. Cooperative control of VSC-HVDC connected offshore wind farm with Low-Voltage Ride-Through capability

    DEFF Research Database (Denmark)

    Liu, Yan; Wang, Xiongfei; Chen, Zhe

    2012-01-01

    The Low-Voltage Ride-Through (LVRT) has become an important grid requirement for offshore wind farms connecting with Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) links. In this paper, a cooperative control strategy with LVRT ability is proposed for a VSC-HVDC connected va...

  10. Operating Standby Redundant Controller to Improve Voltage Source Inverter Reliability

    Science.gov (United States)

    2007-12-01

    was built with two FPGAs programmed using XILINX System Generator and ISE foundation with a discrete algorithm representing the controller...Xilinx’s System Generator after parsing % H:\\Docs\\work_files\\faculty forms\\lab development\\buck_converter\\black_box_buck.vhd 121...this_block.setTopLevelLanguage(’VHDL’); this_block.setEntityName(’code’); % System Generator has to assume that your entity has a

  11. Nonlinear control of voltage source converters in AC-DC power system.

    Science.gov (United States)

    Dash, P K; Nayak, N

    2014-07-01

    This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.

  12. A Voltage Controller in Photo-Voltaic System with Battery Storage for Stand-Alone Applications

    Directory of Open Access Journals (Sweden)

    Ganesh Dharmireddy

    2012-01-01

    Full Text Available This paper proposes the new voltage controller in photo-voltaic system for Stand-Alone Applications with battery energy storage. The output of the PV array is unregulated DC supply due to change in weather conditions. The maximum power is tracked with respect to temperature and irradiance levels by using DC-DC converter. The perturbation and observes algorithm is applied for maximum power point tracking (MPPT purpose. This algorithm is selected due to its ability to withstand against any parameter variation and having high efficiency. The solar cell array powers the steady state energy and the battery compensates the dynamic energy in the system. The aim of the control strategy is to control the SEPIC converter and bi-direction DC-DC converter to operate in suitable modes according to the condition of solar cell and battery, so as to coordinate the two sources of solar cell and battery supplying power and ensure the system operates with high efficiency and behaviors with good dynamic performance. The output of DC-DC converter is converted to AC voltage by using inverter.  The AC output voltage and frequency are regulated. A closed loop voltage control for inverter is done by using unipolar sine wave pulse width modulation (SPWM. The regulated AC voltage is fed to AC standalone loads or grid integration. The overall system is designed, developed and validated by using MATLAB-SIMULINK. The simulation results demonstrate the effective working of MPPT algorithm, control strategy and voltage controller with SPWM technique for inverter in AC standalone load applications.

  13. A Physics-Based Charge-Control Model for InP DHBT Including Current-Blocking Effect

    Institute of Scientific and Technical Information of China (English)

    GE Ji; JIN Zhi; SU Yong-Bo; CHENG Wei; WANG Xian-Wai; CHEN Gao-Peng; LIU Xin-Yu

    2009-01-01

    We develop a physics-based charge-control InP double heterojunction bipolar transistor model including three important effects: current blocking, mobile-charge modulation of the base-collector capacitance and velocity-field modulation in the transit time. The bias-dependent base-collector depletion charge is obtained analytically, which takes into account the mobile-charge modulation. Then, a measurement based voltage-dependent transit time formulation is implemented. As a result, over a wide range of biases, the developed model shows good agreement between the modeled and measured S-parameters and cutoff frequency. Also, the model considering current blocking effect demonstrates more accurate prediction of the output characteristics than conventional vertical bipolar inter company results.

  14. Prediction Model of Battery State of Charge and Control Parameter Optimization for Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Bambang Wahono

    2015-07-01

    Full Text Available This paper presents the construction of a battery state of charge (SOC prediction model and the optimization method of the said model to appropriately control the number of parameters in compliance with the SOC as the battery output objectives. Research Centre for Electrical Power and Mechatronics, Indonesian Institute of Sciences has tested its electric vehicle research prototype on the road, monitoring its voltage, current, temperature, time, vehicle velocity, motor speed, and SOC during the operation. Using this experimental data, the prediction model of battery SOC was built. Stepwise method considering multicollinearity was able to efficiently develops the battery prediction model that describes the multiple control parameters in relation to the characteristic values such as SOC. It was demonstrated that particle swarm optimization (PSO succesfully and efficiently calculated optimal control parameters to optimize evaluation item such as SOC based on the model.

  15. Electronic properties of mesoscopic graphene structures: Charge confinement and control of spin and charge transport

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.co [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412, Moscow (Russian Federation); Giavaras, G. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Bliokh, Yury P. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Freilikher, Valentin [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2011-06-15

    This brief review discusses electronic properties of mesoscopic graphene-based structures. These allow controlling the confinement and transport of charge and spin; thus, they are of interest not only for fundamental research, but also for applications. The graphene-related topics covered here are: edges, nanoribbons, quantum dots, pn-junctions, pnp-structures, and quantum barriers and waveguides. This review is partly intended as a short introduction to graphene mesoscopics.

  16. ARTIFICIAL NEURAL NETWORK CONTROLLER BASED DISTRIBUTION STATIC COMPENSATOR FOR VOLTAGE SAG MITIGATION

    Directory of Open Access Journals (Sweden)

    D. Rajasekaran

    2013-01-01

    Full Text Available Switching of loads, capacitors, along with the proliferation of power electronics equipment, non-linear loads in industrial, commercial and domestic applications have lead to power quality issues in the distribution system. Power quality issues such as voltage sag, voltage swell and harmonics, which are certainly major concerning issues in the present era. These issues can lead to failure or malfunction of the many sensitive loads connected to the distribution system, thus incurring a high cost for end users. Power quality problems are solved by advanced custom power devices. This study presents how the custom power device Distribution Static Compensator (D-STATCOM is used to mitigate voltage sag and voltage harmonics in distribution system. Artificial Neural Network (ANN controller based D-STATCOM is simulated in MATLAB-SIMULINK environment. Prototype model for single phase D-STATCOM is developed to verify the results. The simulation and hardware results show clearly the performance of the D-STATCOM in mitigating voltage sag and voltage harmonics in distribution system.

  17. Voltage Stability of Long Transmission Line Equipped with a Thyristor Controlled Series Capacitor

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2012-01-01

    Full Text Available Problem statement: Power-Voltage curve provides very important information for voltage stability analysis. The exact long transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not easy task to achieve the power-voltage curve characteristics of power system with the exact long line model equipeed with a Thyristor Controlled Series Capacitor (TCSC. Approach: This study applies the concept of the Newton-Raphson method to iteratively solve the nonlinear power flow equations. The Power-Voltage (P-V curve charateristic of the system without line loss and with line loss are plotted and compared on various cases. Results: It is found from the study that the resistance of the line obviously provides the negative effects on the voltage stability. The line loss causes in the decrement of the critical point. In addition, it is found that the leading power factor can increase the critical point of P-V curve. Conclusion: The exact long line model should be considered for voltage stability analysis of the system with the long transmission line.

  18. Voltage Stability of Medium Transmission Line Equipped with a Thyristor Controlled Series Capacitor

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2012-01-01

    Full Text Available Problem statement: Power-Voltage curve provides very important information for voltage stability analysis. The exact medium transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not an easy task to achieve the power-voltage curve characteristics of power system with the exact medium line model equipped with a. Thyristor Controlled Series Capacitor (TCSC. Approach: This study applies the concept of the Newton-Raphson method to iteratively solve the nonlinear power flow equations. The Power-Voltage (P-V curve characteristic of the system without line loss and with line loss are plotted and compared with various cases. Results: It is found from the study that the resistance of the line obviously provides the negative effects on the voltage stability. The line loss causes in the decrement of the critical point. In addition, it is found that the leading power factor can increase the critical point of P-V curve. Conclusion: The exact medium line model should be considered for voltage stability analysis of the system with the medium transmission line.

  19. LED Current Balance Using a Variable Voltage Regulator with Low Dropout vDS Control

    Directory of Open Access Journals (Sweden)

    Hung-I Hsieh

    2017-02-01

    Full Text Available A cost-effective light-emitting diode (LED current balance strategy using a variable voltage regulator (VVR with low dropout vDS control is proposed. This can regulate the multiple metal-oxide-semiconductor field-effect transistors (MOSFETs of the linear current regulators (LCR, maintaining low dropout vDS on the flat vGS-characteristic curves and making all drain currents almost the same. Simple group LCRs respectively loaded with a string LED are employed to implement the theme. The voltage VVdc from a VVR is synthesized by a string LED voltage NvD, source voltage vR, and a specified low dropout vDS = VQ. The VVdc updates instantly, through the control loop of the master LCR, which means that all slave MOSFETs have almost the same biases on their flat vGS-characteristic curves. This leads to all of the string LED currents being equal to each other, producing an almost even luminance. An experimental setup with microchip control is built to verify the estimations. Experimental results show that the luminance of all of the string LEDs are almost equal to one another, with a maximum deviation below 1% during a wide dimming range, while keeping all vDS of the MOSFETs at a low dropout voltage, as expected.

  20. Control Strategy of Three-Phase Photovoltaic Inverter under Low-Voltage Ride-Through Condition

    Directory of Open Access Journals (Sweden)

    Xianbo Wang

    2015-01-01

    Full Text Available The new energy promoting community has recently witnessed a surge of developments in photovoltaic power generation technologies. To fulfill the grid code requirement of photovoltaic inverter under low-voltage ride-through (LVRT condition, by utilizing the asymmetry feature of grid voltage, this paper aims to control both restraining negative sequence current and reactive power fluctuation on grid side to maintain balanced output of inverter. Two mathematical inverter models of grid-connected inverter containing LCL grid-side filter under both symmetrical and asymmetric grid are proposed. PR controller method is put forward based on inverter model under asymmetric grid. To ensure the stable operation of the inverter, grid voltage feedforward method is introduced to restrain current shock at the moment of voltage drop. Stable grid-connected operation and LVRT ability at grid drop have been achieved via a combination of rapid positive and negative sequence component extraction of accurate grid voltage synchronizing signals. Simulation and experimental results have verified the superior effectiveness of our proposed control strategy.

  1. Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control

    Science.gov (United States)

    Omole, Adedamola

    Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid, although this feature is currently rarely utilized as most DG systems are designed to operate with unity power factor and supply real power only to the grid. In this work, the voltage stability of a power system embedded with PV DG is examined in the context of the high reactive power requirement after a voltage sag or fault. A real-time dynamic multi-function power controller that enables renewable source PV DGs to provide the reactive power support necessary to maintain the voltage stability of the microgrid, and consequently, the wider power system is proposed. The loadability limit necessary to maintain the voltage stability of an interconnected microgrid is determined by using bifurcation analysis to test for the singularity of the network Jacobian and load differential equations with and without the contribution of the DG. The maximum and minimum real and reactive power support permissible from the DG is obtained from the loadability limit and used as the limiting factors in controlling the real and reactive power contribution from the PV source. The designed controller regulates the voltage output based on instantaneous power theory at the point-of-common coupling (PCC) while the reactive power supply is controlled by means of the power factor and reactive current droop method. The control method is implemented in a modified IEEE 13-bus test feeder system using PSCADRTM power system analysis software and is applied to the model of a Tampa ElectricRTM PV installation at Lowry Park Zoo in Tampa, FL. This dissertation accomplishes the systematic analysis of the voltage impact of a PV DG-embedded power distribution system. The method employed in this work bases the contribution of the PV resource on the voltage stability margins of the microgrid rather than the commonly used loss-of-load probability (LOLP) and effective load-carrying capability (ELCC) measures. The results of

  2. Design of A Grid Integrated PV System with MPPT Control and Voltage Oriented Controller using MATLAB/PLECES

    Science.gov (United States)

    Soreng, Bineeta; Behera, Pradyumna; Pradhan, Raseswari

    2017-08-01

    This paper presents model of a grid-integrated photovoltaic array with Maximum Power Point Tracker (MPPT) and voltage oriented controller. The MPPT of the PV array is usually an essential part of PV system as MPPT helps the operating point of the solar array to align its maximum power point. In this model, the MPPT along with a DC-DC converter lets a PV generator to produce continuous power, despite of the measurement conditions. The neutral-point-clamped converter (NPC) with a boost converter raises the voltage from the panels to the DC-link. An LCL-filter smoothens the current ripple caused by the PWM modulation of the grid-side inverter. In addition to the MPPT, the system has two more two controllers, such as voltage controller and a current controller. The voltage control has a PI controller to regulate the PV voltage to optimal level by controlling the amount of current injected into the boost stage. Here, the grid-side converter transfers the power from the DC-link into the grid and maintains the DC-link voltage. Three-phase PV inverters are used for off-grid or designed to create utility frequency AC. The PV system can be connected in series or parallel to get the desired output power. To justify the working of this model, the grid-integrated PV system has been designed in MATLAB/PLECS. The simulation shows the P-V curve of implemented PV Array consisting 4 X 20 modules, reactive, real power, grid voltage and current.

  3. Enhanced Decoupled Double Synchronous Reference Frame Current Controller for Unbalanced Grid-Voltage Conditions

    DEFF Research Database (Denmark)

    Reyes, M.; Rodriguez, Pedro; Vazquez, S.;

    2012-01-01

    . In these codes, the injection of positive- and negative-sequence current components becomes necessary for fulfilling, among others, the low-voltage ride-through requirements during balanced and unbalanced grid faults. However, the performance of classical dq current controllers, applied to power converters......, under unbalanced grid-voltage conditions is highly deficient, due to the unavoidable appearance of current oscillations. This paper analyzes the performance of the double synchronous reference frame controller and improves its structure by adding a decoupling network for estimating and compensating...

  4. Voltage-controlled narrowband and wide, variable-range four-segment quartz crystal oscillator.

    Science.gov (United States)

    Ruslan, Ruzaini; Satoh, Tomio; Akitsu, Tetsuya

    2012-03-01

    In this work, our goal is to develop a voltage-controlled variable-frequency quartz crystal oscillator with narrowband response, wide, variable frequency range and the capacity to oscillate across the series resonance frequency using a four-segment configuration of a quartz crystal oscillator. In conventional quartz oscillators, the quartz resonator is inserted in the feedback loop between the input and the output of the active circuit, providing sufficient gain and the phase relation. In the oscillator developed here, the quartz crystal resonator is inserted between the loop circuit and the ground potential. The performance of the voltage-controlled variable-frequency oscillator is demonstrated across the series resonance frequency.

  5. Active power filter for medium voltage networks with predictive current control

    Energy Technology Data Exchange (ETDEWEB)

    Verne, Santiago A.; Valla, Maria I. [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata and CONICET, La Plata (Argentina)

    2010-12-15

    A transformer less Shunt Active Power Filter (SAPF) for medium voltage distribution networks based on Multilevel Diode Clamped Inverter is presented in this paper. Converter current control is based on a Model Predictive strategy, which gives very fast current response. Also, the algorithm includes voltage balancing capability which is essential for proper converter operation. The presented current control algorithm is naturally applicable to converters with an arbitrary number of levels with reduced computational effort by virtue of the incorporation of switching restrictions which are necessary for reliable converter operation. The performance of the proposed algorithm is evaluated by means of computer simulations. (author)

  6. Internal voltage control of hydrogen-oxygen fuel cells: Feasibility study

    Science.gov (United States)

    Prokopius, P. R.

    1975-01-01

    An experimental study was conducted to assess the feasibility of internal voltage regulation of fuel cell systems. Two methods were tested. In one, reactant partial pressure was used as the voltage control parameter and in the other reactant total pressure was used for control. Both techniques were breadboarded and tested on a single alkaline-electrolyte fuel cell. Both methods were found to be possible forms of regulation, however, of the two the total pressure technique would be more efficient, simpler to apply and would provide better transient characteristics.

  7. Design to conditioning circuits of dynamic compensation of reactive power in the intelligence voltage controller

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easily calculate the power factor,and Voltage controller in the microcontroller to determine whether input the compensation capacitance according to the size of power factor,the paper also analyzes the principle of capacitance compensation and calculation method. Dynamic compensation for the entire process is quick and accurate.

  8. Modeling and Control of Low Voltage Flexible Units for Enhanced Operation of Distribution Feeders

    DEFF Research Database (Denmark)

    Raboni, Pietro; Hu, Weihao; Chaudhary, Sanjay

    2013-01-01

    Battery (EVB) is proposed for providing primary regulation in grid connected mode and for hierarchically manage an islanded LV distribution feeder. The unit models are described and a novel EVB model directly based on manufacturer’s data is proposed and evaluated comparing its performances with Sim......PowerSystems library block. Moreover a voltage dependant power term is applied to the Voltage-Source Converter (VSC) control scheme of the EVB for improving the performances of the islanded feeder. The control is tested in case of under frequency and consequent load shedding occurring at the residential feeder...

  9. Modeling of the CIGRE Low Voltage Test Distribution Network and the Development of Appropriate Controllers

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    controller. The control system is tested in the distribution test network set up by CIGRE. The new approach of the PV controller is done in such a way that it can control AC and DC voltage of the PV converter during dynamic conditions. The battery controller is also developed in such a way that it can...... quality issues. The main focus of this paper is on development of controllers for a distribution system with different DG’s and especially development of a Photovoltaic (PV) controller using a Static Compensator (STATCOM) controller and on modeling of a Battery Storage System (BSS) also based on a STATCOM...

  10. Improved Control Strategy for DFIG Wind Turbines for Low Voltage Ride Through

    Directory of Open Access Journals (Sweden)

    Chanxia Zhu

    2013-02-01

    Full Text Available This paper presents an improved control strategy for both the rotor side converter (RSC and grid side converter (GSC of a doubly fed induction generator (DFIG-based wind turbine (WT system to enhance the low voltage ride through (LVRT capability. Within the proposed control strategy, the RSC control introduces transient feed-forward compensation terms to mitigate the high frequency harmonic components and reduce the surge in the rotor currents. The proposed GSC control scheme also introduces a compensation term reflecting the instantaneous variation of the output power of the rotor side converter with consideration of the instantaneous power of grid filter impendence to keep the dc-link voltage nearly constant during the grid faults. To provide precise control, non-ideal proportional resonant (PR controllers for both the RSC and GSC current regulation are employed to further improve dynamic performance. Simulations performed in Matlab/Simulink verify the effectiveness of the proposed control strategy.

  11. Compound control method of neutral point voltage of three level NPC inverter based on the vector method of virtual space and hysteresis control

    Science.gov (United States)

    Yang, Fengping; Xiao, Fangfei

    2017-03-01

    Current control methods include hardware control and software control corresponding to the inherent unbalance problem of neutral point voltage in three level NPC inverter. The hardware control is rarely used due to its high cost. In this paper, a new compound control method has been presented based on the vector method of virtual space and traditional hysteresis control of neutral point voltage, which can make up the shortcoming of the virtual control without the feedback control system of neutral point voltage and the blind area of hysteresis control and control the deviation and wave of neutral point voltage. The accuracy of this method has been demonstrated by simulation.

  12. Design of Multi-unit Control System of High Voltage Power Supply for LASCAR Scintillator Detector Array

    Institute of Scientific and Technical Information of China (English)

    WuLijie; WangJinchuan; XiaoGuoqing; GuoZhongyan; ZhanWenlong; QiHuirong; XuZhiguo; ZhangLi; DingXianli; XuHushan; SunZhiyu; LiJiaxing; LiChen; WangMeng; ChenLixin; HuZhengguo; MaoRuishi; ZhaoTiecheng

    2003-01-01

    The power voltages of Photomultipliers (PMTs) at RIBLL LASCAR scintillator detector array are distributed between 900 V and 1 800 V irregularly. 392 CC123 modules are employed to supply high voltage for the PMT array. The CC123 module serves as PMT interface groupware package, and it can transform +12 V DC input voltage to ranges of 0~-2200 V for the PMT power supply corresponding to 0~+5 V output voltage from the control board crate. The relation of PMT power supply with the output voltage of the control crate is shown in Fig.1.

  13. Application of Newton's optimal power flow in voltage/reactive power control

    Energy Technology Data Exchange (ETDEWEB)

    Bjelogrlic, M.; Babic, B.S. (Electric Power Board of Serbia, Belgrade (YU)); Calovic, M.S. (Dept. of Electrical Engineering, University of Belgrade, Belgrade (YU)); Ristanovic, P. (Institute Nikola Tesla, Belgrade (YU))

    1990-11-01

    This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

  14. Conformational control of benzophenone-sensitized charge transfer in dinucleotides.

    Science.gov (United States)

    Merz, Thomas; Wenninger, Matthias; Weinberger, Michael; Riedle, Eberhard; Wagenknecht, Hans-Achim; Schütz, Martin

    2013-11-14

    Charge transfer in DNA cannot be understood without addressing the complex conformational flexibility, which occurs on a wide range of timescales. In order to reduce this complexity four dinucleotide models 1X consisting of benzophenone linked by a phosphodiester to one of the natural nucleosides X = A, G, T, C were studied in water and methanol. The theoretical work focuses on the dynamics and electronic structure of 1G. Predominant conformations in the two solvents were obtained by molecular dynamics simulations. 1G in MeOH adopts mainly an open geometry with a distance of 12–16 Å between the two aromatic parts. In H2O the two parts of 1G form primarily a stacked conformation yielding a distance of 5–6 Å. The low-lying excited states were investigated by electronic structure theory in a QM/MM environment for representative snapshots of the trajectories. Photo-induced intramolecular charge transfer in the S1 state occurs exclusively in the stacked conformation. Ultrafast transient absorption spectroscopy with 1X reveals fast charge transfer from S1 in both solvents with varying yields. Significant charge transfer from the T1 state is only found for the nucleobases with the lowest oxidation potential: in H2O, charge transfer occurs with 3.2 × 10(9) s(-1) for 1A and 6.0 × 10(9) s(-1) for 1G. The reorganization energy remains nearly unchanged going from MeOH to the more polar H2O. The electronic coupling is rather low even for the stacked conformation with H(AB) = 3 meV and explains the moderate charge transfer rates. The solvent controls the conformational distribution and therefore gates the charge transfer due to differences in distance and stacking.

  15. Experience with voltage control from large offshore windfarms: The Danish case

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav

    2009-01-01

    This paper gives an overview of the state of the art and lists future challenges to reactive power and voltage control in the Danish transmission system in relation to large offshore windfarms. Today, the reliable and stable operation of the Danish transmission system is based on the voltage...... and several smaller ones, has shown that the efficient use of windfarms' reactive power and voltage control for the on-land transmission system might be limited by several factors. Among such limiting factors are the reactive power and current capability limits of the electronic power converters...... and switchable capacitor banks of the offshore wind turbines, which are smaller than those of central power plants measured per unit of the active power rating. Combine this with the use of AC cables, tens of kilometres long, to connect the large offshore windfarms to the on-land transmission system...

  16. Effects of voltage control in utility interactive dispersed storage and generation systems

    Energy Technology Data Exchange (ETDEWEB)

    Kirkham, H.; Das, R.

    1983-03-15

    When a small generator is connected to the distribution system, the voltage at the point of interconnection is determined largely by the system and not the generator. This report examines the effect on the generator, on the load voltage and on the distribution system of a number of different voltage control strategies in the generator. Synchronous generators with three kinds of exciter control are considered, as well as induction generators and dc/ac inverters, with and without capacitor compensation. The effect of varying input power during operation (which may be experienced by generators based on renewable resources) is explored, as well as the effect of connecting and disconnecting the generator at ten percent of its rated power.

  17. Control system design of high-voltage live cleaning robot based on security

    Institute of Scientific and Technical Information of China (English)

    谢霄鹏; 夏红卫; 杨汝清

    2004-01-01

    High-voltage live cleaning robot works in the hot-line environment (220 kV/330 kV), and so the safety of its application and equipment is most important. In terms of safety, the designs of robot mechanism and control system have been discussed, and the test data are given in control system of model machine. The model machine of high-voltage live cleaning robot can meet the need of cleaning basically in common condition. From manual operation to automation, the cleaning efficiency is improved. The robot can decrease amount of work, and ensure the security. Among high-voltage live cleaning equipment in China, the cleaning robot is advanced in automation and intelligence.

  18. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2014-01-01

    The inherent double line ripple power in singlephase systems is adverse to the converter performance, e.g. limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active converter topology based...... on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling of the proposed system...... is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the harmonic reference frame for ripple power compensation. Special attention is given to the bandwidth...

  19. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2015-01-01

    converter topology based on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling......The inherent double line ripple power in single-phase systems is adverse to the performance of power electronics converters, e.g. limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active...... of the proposed system is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the stationary reference frame for ripple power compensation. Special attention...

  20. A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain;

    2015-01-01

    This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC-HVDC......) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

  1. Voltage control in Z-source inverter using low cost microcontroller for undergraduate approach

    Science.gov (United States)

    Zulkifli, Shamsul Aizam; Sewang, Mohd Rizal; Salimin, Suriana; Shah, Noor Mazliza Badrul

    2017-09-01

    This paper is focussing on controlling the output voltage of Z-Source Inverter (ZSI) using a low cost microcontroller with MATLAB-Simulink that has been used for interfacing the voltage control at the output of ZSI. The key advantage of this system is the ability of a low cost microcontroller to process the voltage control blocks based on the mathematical equations created in MATLAB-Simulink. The Proportional Integral (PI) control equations are been applied and then, been downloaded to the microcontroller for observing the changes on the voltage output regarding to the changes on the reference on the PI. The system has been simulated in MATLAB and been verified with the hardware setup. As the results, the Raspberry Pi and Arduino that have been used in this work are able to respond well when there is a change of ZSI output. It proofed that, by applying/introducing this method to student in undergraduate level, it will help the student to understand more on the process of the power converter combine with a control feedback function that can be applied at low cost microcontroller.

  2. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    OpenAIRE

    2014-01-01

    In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast contro...

  3. Complete Charging for Piezoelectric Energy Harvesting System

    Institute of Scientific and Technical Information of China (English)

    樊康旗; 徐春辉; 王卫东

    2014-01-01

    Under an in-phase assumption, the complete charging for an energy harvesting system is studied, which consists of a piezoelectric energy harvester (PEH), a bridge rectifier, a filter capacitor, a switch, a controller and a rechargeable battery. For the transient charging, the results indicate that the voltage across the filter capacitor increases as the charging proceeds, which is consistent with that reported in the literature. However, a new finding shows that the charging rate and energy harvesting efficiency decrease over time after their respective peak values are acquired. For the steady-state charging, the results reveal that the energy harvesting efficiency can be adjusted by altering the critical charging voltage that controls the transition of the system. The optimal energy harvesting efficiency is limited by the optimal efficiency of the transient charging. Finally, the relationship between the critical charging voltage and the equivalent resistance of the controller and rechargeable battery is established explicitly.

  4. Control of SiC Based Front-End Rectifier under Unbalanced Supply Voltage

    DEFF Research Database (Denmark)

    Maheshwari, Ramkrishan; Trintis, Ionut; Gohil, Ghanshyamsinh Vijaysinh

    2015-01-01

    A voltage source converter is used as a front end converter typically. In this paper, a converter which is realized using SiC MOSFET is considered. Due to SiC MOSFET, a switching frequency more than 50 kHz can be achieved. This can help increasing the current control loop bandwidth, which...

  5. Voltage and Frequency Control for Future Power Systems: the ELECTRA IRP Proposal

    DEFF Research Database (Denmark)

    D’hulst, R.; Merino Fernandez, J.; Rikos, E.;

    2015-01-01

    In this paper a high level functional architecture for frequency and voltage control for the future (2030+) power system is presented. The proposal suggests a decomposition of the present organization of power system operation into a ”web of cells”. Each cell in this web is managed by a single sy...

  6. PowerFactory model for multi-terminal HVDC network with DC voltage droop control

    DEFF Research Database (Denmark)

    Korompili, Asimenia; Wu, Qiuwei

    Nowadays, most of the installed HVDC systems are based on line commutated converters (LCC), since this technology offers a series of advantages, mainly low costs and losses. However, voltage source converters (VSCs) have recently drawn more and more attention, due to their high controllability...

  7. Tertiary Control of Voltage Unbalance Compensation for Optimal Power Quality in Islanded Microgrids

    DEFF Research Database (Denmark)

    Meng, Lexuan; Tang, Fen; Savaghebi, Mehdi;

    2014-01-01

    the voltage unbalance limits in local buses and DG terminals. This method realizes multi-power-quality-level control in a multi-bus islanded system by optimally utilizing DGs as distributed compensators and saves the investment for additional compensation equipment. Hardware-in-the-loop results demonstrate...

  8. Tertiary control of voltage unbalance compensation for optimal power quality in islanded microgrids

    DEFF Research Database (Denmark)

    Meng, Lexuan; Tang, Fen; Savaghebi, Mehdi

    2016-01-01

    DG considering the voltage unbalance limits in local buses and DG terminals. This method realizes multi-power-quality-level control in a multi-bus islanded system by optimally utilizing DGs as distributed compensators and saves the investment for additional compensation equipment. Hardware-in...

  9. Model Predictive Controlled Active NPC Inverter for Voltage Stress Balancing Among the Semiconductor Power Switches

    Science.gov (United States)

    Parvez Akter, Md.; Dah-Chuan Lu, Dylan

    2017-07-01

    This paper presents a model predictive controlled three-level three-phase active neutral-point-clamped (ANPC) inverter for distributing the voltage stress among the semiconductor power switches as well as balancing the neutral-point voltage. The model predictive control (MPC) concept uses the discrete variables and effectively operates the ANPC inverter by avoiding any linear controller or modulation techniques. A 4.0 kW three-level three-phase ANPC inverter is developed in the MATLAB/Simulink environment to verify the effectiveness of the proposed MPC scheme. The results confirm that the proposed model predictive controlled ANPC inverter equally distributes the voltage across all the semiconductor power switches and provides lowest THD (0.99%) compared with the traditional NPC inverter. Moreover, the neutral-point voltage balancing is accurately maintained by the proposed MPC algorithm. Furthermore, this MPC concept shows the robustness capability against the parameter uncertainties of the system which is also analyzed by MATLAB/Simulink.

  10. Comparison of two voltage control strategies for a wind power plant

    DEFF Research Database (Denmark)

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

    2011-01-01

    Larger percentages of wind power penetration translate to more demanding requirements from grid codes. Recently, voltage support at the point of connection has been introduced by several grid codes from around the world, thus, making it important to analyze this control when applied to wind power...

  11. Flexible Microgrid Power Quality Enhancement Using Adaptive Hybrid Voltage and Current Controller

    DEFF Research Database (Denmark)

    He, Jinwei; Li, Yun Wei; Blaabjerg, Frede

    2014-01-01

    To accomplish superior harmonic compensation performance using distributed generation (DG) unit power electronics interfaces, an adaptive hybrid voltage and current controlled method (HCM) is proposed in this paper. It shows that the proposed adaptive HCM can reduce the numbers of low-pass/bandpa...

  12. Autonomous Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

    2013-01-01

    Recently, there is an increasing interest in using distributed generators (DGs) not only to inject power into the grid, but also to enhance the power quality. In this paper, a stationary-frame control method for voltage unbalance compensation in an islanded microgrid is proposed. This method...

  13. A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter

    Institute of Scientific and Technical Information of China (English)

    屈克庆; 陈国呈; 孙承波

    2004-01-01

    This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.

  14. Voltage Tracking of a DC-DC Flyback Converter Using Neural Network Control

    Directory of Open Access Journals (Sweden)

    Wahyu Mulyo Utomo

    2012-01-01

    Full Text Available This paper proposes a neural network control scheme of a DC-DC Flyback converter that will step up a 12V DC and applied it on brushless DC motor with 12 and 24V dc. In this technique, a back propagation learning algorithm is derived. The controller is designed to track the output voltage of the DC-DC converter and to improve performance of the Flyback converter during transient operations. Furthermore, to investigate the effectiveness of the proposed controller, some operations such as starting-up and reference voltage variations are verified. The numerical simulation results show that the proposed controller has a better performance compare to the conventional PI-Controller method.

  15. A nonlinear optimization approach for UPFC power flow control and voltage security

    Science.gov (United States)

    Kalyani, Radha Padma

    This dissertation provides a nonlinear optimization algorithm for the long term control of Unified Power Flow Controller (UPFC) to remove overloads and voltage violations by optimized control of power flows and voltages in the power network. It provides a control strategy for finding the long term control settings of one or more UPFCs by considering all the possible settings and all the (N-1) topologies of a power network. Also, a simple evolutionary algorithm (EA) has been proposed for the placement of more than one UPFC in large power systems. In this publication dissertation, Paper 1 proposes the algorithm and provides the mathematical and empirical evidence. Paper 2 focuses on comparing the proposed algorithm with Linear Programming (LP) based corrective method proposed in literature recently and mitigating cascading failures in larger power systems. EA for placement along with preliminary results of the nonlinear optimization is given in Paper 3.

  16. Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

    Science.gov (United States)

    Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

    2016-08-01

    According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

  17. Distributed voltage control and load sharing for inverter-interfaced microdrid with resistive lines

    DEFF Research Database (Denmark)

    Golsorkhi, Mohammad S.; Lu, D. D C; Shafiee, Q.

    2016-01-01

    method is based upon the practical assumption of resistive network impedance. In this context, a V-I droop mechanism is adopted in the primary control level, where GPS timing is used to synchronize the control agents. A new distributed secondary control method based on consensus protocol is introduced......This paper proposes a new distributed control method for coordination of distributed energy resources (DERs) in low-voltage resistive microgrids. The proposed framework consists of two level structure; primary and secondary control. Unlike the existing distributed control methods, the proposed...

  18. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2014-01-01

    on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling of the proposed system...... is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the harmonic reference frame for ripple power compensation. Special attention is given to the bandwidth...

  19. Voltage-controlled spin selection in a magnetic resonant tunneling diode.

    Science.gov (United States)

    Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

    2003-06-20

    We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

  20. Voltage-controlled sub-terahertz radiation transmission through GaN quantum well structure

    Science.gov (United States)

    Laurent, T.; Sharma, R.; Torres, J.; Nouvel, P.; Blin, S.; Varani, L.; Cordier, Y.; Chmielowska, M.; Chenot, S.; Faurie, J.-P.; Beaumont, B.; Shiktorov, P.; Starikov, E.; Gruzinskis, V.; Korotyeyev, V. V.; Kochelap, V. A.

    2011-08-01

    We report on measurements of radiation transmission in the 0.220-0.325 THz frequency range through GaN quantum wells grown on sapphire substrates at nitrogen and room temperatures. Significant enhancement of the transmitted beam intensity with applied voltage is found at nitrogen temperature. This effect is explained by changes in the mobility of two-dimensional electrons under electric bias. We have clarified which physical mechanism modifies the electron mobility and we suggest that the effect of voltage-controlled sub-terahertz transmission can be used for the development of electro-optic modulators operating in the sub-THz frequency range.

  1. Harmonics and voltage stability analysis in power systems including thyristor-controlled reactor

    Indian Academy of Sciences (India)

    M Uzunoglu

    2005-02-01

    In this study, non-sinusoidal quantities and voltage stability, both known as power quality criteria, are examined together in detail. The widespread use of power electronics elements cause the existence of significant non-sinusoidal quantities in the system. These non-sinusoidal quantities can create serious harmonic distortions in transmission and distribution systems. In this paper, harmonic generation of a static VAR compensator with thyristor-controlled reactor and effects of the harmonics on steady-state voltage stability are examined for various operational conditions.

  2. The Control of Voltage and Frequency of Self-excited Three-Phase Induction Generator

    Directory of Open Access Journals (Sweden)

    Ionel Dragomirescu

    2011-10-01

    Full Text Available In this work it is presented the control of voltage and frequency of threephase induction generator in autonomous regime. It is adjusted the intensity of voltage and frequency at the terminals of the consumer by means of frequency converter, in conditions of driving the induction generator at constant speed. System testing and measurements were carried out by the Laboratory for Designing and Testing of Equipment Excitation and Automation of the Center for Research in Hydraulics, Automation and Thermal Processes (CCHAPT within “Eftimie Murgu” University of Resita.

  3. Improving the Mitigation of Voltage Flicker by Usage of Fuzzy Control in a Distribution Static Synchronous Compensator (DSTATCOM

    Directory of Open Access Journals (Sweden)

    Saeed Abazari

    2009-06-01

    Full Text Available This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitigation of the voltage flicker in a distribution system. The voltage flicker is produced by a large variable load absorbing continuously changing currents such as an arc furnace. The DSTATCOM includes a voltage-sourced PWM inverter and its control system. The control strategy of the DSTATCOM plays an important role in maintaining the voltage flicker. Here, the DSTATCOM controller is designed with two types of controllers, linear proportional-integral (PI and nonlinear fuzzy logic. The simulation of the DSTATCOM with 3MVar reactive power on a 25 KV distribution network is carried out in MATLAB/SIMULINK software. Finaly, fuzzy controllers were evaluated by comparing its performance with the PI controllers. It is observed that the fuzzy controllers are very superior in mitigating the voltage flicker.

  4. Control of Grid Interactive PV Inverters for High Penetration in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Demirok, Erhan

    . On the other hand, unnecessarily strict grid connection requirements may cause less utilization of solar potential and may lead to additional cost on PV plants. PV based generating plants are basically interfaced to electricity grid via power inverters. Hardware and control design requirements...... for this problem but PV inverters connected to highly capacitive networks are able to employ extra current and voltage harmonics compensation to avoid triggering network resonances at low order frequencies. The barriers such as harmonics interaction, flicker, fault current contribution and dc current injections...... networks, PV inverter current limitation, transformer and cable/line thermal limits with increased reactive power flow. Therefore, the highest voltage drop should be realized with minimum reactive power absorption from the grid. Weak points of voltage support strategies which were already imposed by grid...

  5. Study of seismic response and vibration control of High voltage electrical equipment damper based on TMD

    Science.gov (United States)

    Liu, Chuncheng; Wang, Chongyang; Mao, Long; Zha, Chuanming

    2016-11-01

    Substation high voltage electrical equipment such as mutual inductor, circuit interrupter, disconnecting switch, etc., has played a key role in maintaining the normal operation of the power system. When the earthquake disaster, the electrical equipment of the porcelain in the transformer substation is the most easily to damage, causing great economic losses. In this paper, using the method of numerical analysis, the establishment of a typical high voltage electrical equipment of three dimensional finite element model, to study the seismic response of a typical SF6 circuit breaker, at the same time, analysis and contrast the installation ring tuned mass damper (TMD damper for short), by changing the damper damping coefficient and the mass block, install annular TMD vibration control effect is studied. The results of the study for guiding the seismic design of high voltage electrical equipment to provide valuable reference.

  6. Power Quality Improvement And Mitigation Of Voltage Sag And Current Swell Using Distributed Power Flow Controller

    Directory of Open Access Journals (Sweden)

    P.NIRMALA

    2014-09-01

    Full Text Available Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, That higher power quality should be considered. In this paper, DPFC which is similar to unified power flow controller (UPFC in structure, which is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converter devices should be eliminated and three-phase series converter is divided to several single-phase series distributed converters through the power transmission line. And also to detect the voltage sags and find out the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Mat lab/Simulink environment which show the effectiveness of the proposed structure

  7. CLOSED LOOP CONTROL OF THREE PORT CONVERTER WITH HIGH VOLTAGE GAIN

    Directory of Open Access Journals (Sweden)

    Santhi Mary Antony A

    2015-08-01

    Full Text Available Photovoltaic (PV system is one of the best renewable energy sources for power generation system due to their pollution free and low cost properties. The PV cells has less efficiency compared to other source of power generation. The system efficiency is improved by reducing components count, which reduces the losses. In this paper a new three port converter (TPC is proposed for stand-alone renewable power applications. The proposed converter has three switches to achieve the power flow control. Single inductor is used for common energy transfer element for two different sources. The coupled inductor is used to increase the voltage conversion ratio with reasonable duty cycle. Thus the proposed converter has high voltage gain with less components count. The output voltage is regulated through feedback network. The system performance is verified through simulation results.

  8. New Requirements of the Voltage/VAR Function for Smart Inverter in Distributed Generation Control

    Directory of Open Access Journals (Sweden)

    Yun-Su Kim

    2016-11-01

    Full Text Available International Electronical Committee (IEC 61850-90-7 is a part of the IEC 61850 series which specifies the advanced functions and object models for power converter based Distributed Energy Resources (DERs. One of its functions, the Voltage/VAR (V/V control function, is used to enhance the stability and the reliability of the voltage in the distribution system. The conventional V/V function acts mainly for flattening the voltage profile as for a basic grid support function. Currently, other objectives such as the minimization of line loss and the operational costs reduction are coming into the spotlight. In order to attain these objectives, the V/V function and hence the DER units shall actively respond to the change of distribution system conditions. In this paper, the modification of V/V function and new requirements are proposed. To derive new requirements of V/V function, loss minimization is applied to a particle swarm optimization (PSO algorithm where the condition of voltage constraint is considered not to deteriorate the voltage stability of the distribution system.

  9. Identification procedures for the charge-controlled nonlinear noise model of microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier Andrea; Florian, Corrado; Borgarino, Mattia

    2004-05-01

    The basic features of the recently proposed Charge-Controlled Non-linear Noise (CCNN) model for the prediction of low-to-high-frequency noise up-conversion in electron devices under large-signal RF operation are synthetically presented. It is shown that the different noise generation phenomena within the device can be described by four equivalent noise sources, which are connected at the ports of a "noiseless" device model and are non-linearly controlled by the time-varying instantaneous values of the intrinsic device voltages. For the empirical identification of the voltage-controlled equivalent noise sources, different possible characterization procedures, based not only on conventional low-frequency noise data, but also on different types of noise measurements carried out under large-signal RF operating conditions are discussed. As an example of application, the measurement-based identification of the CCNN model for a GaInP heterojunction bipolar microwave transistor is presented. Preliminary validation results show that the proposed model can describe with adequate accuracy not only the low-frequency noise of the HBT, but also its phase-noise performance in a prototype VCO implemented by using the same monolithic GaAs technology.

  10. High performance AC–DC control power supply for low voltage ride through inverters

    Indian Academy of Sciences (India)

    K Saichand; Akshay Kumrawat; Vinod John

    2016-02-01

    This paper presents a control power supply (CPS) design which is used to feed power to the subsystems of a power converter. The CPS design presented here maintains a constant 24Vdc output even over a wide (90Vrms to 270Vrms ) ac voltage variation at its input for a High Power Converter (HPC). The circuit design and closed loop control design of such a CPS are presented. During starting, the power supply to the control circuitry of the CPS in turn is obtained using a separate start-up power supply. The various design issues and details of the on-board power supply and start-up power circuit to ensure the reliable start-up and shut down of the CPS are analyzed. The CPS was tested for wide input voltage range (vin) and the performance validates the design. The CPS has also been tested for an input side voltage sag and its performance allows the HPC to meet the low voltage ride-through requirements.

  11. Impact of the Converter Control Strategies on the Drive Train of Wind Turbine during Voltage Dips

    Directory of Open Access Journals (Sweden)

    Fenglin Miao

    2015-10-01

    Full Text Available The impact of converter control strategies on the drive train of wind turbines during voltage dips is investigated in this paper using a full electromechanical model. Aerodynamics and tower vibration are taken into consideration by means of a simulation program, named FAST. Detailed gearbox and electrical subsystems are represented in MATLAB. The dynamic response of electromagnetic torque and its impact on the mechanical variables are the concern in this paper and the response of electrical variables is less discussed. From the mechanical aspects, the effect of rising power recovery speed and unsymmetrical voltage dips are analyzed on the basis of the dynamic response of the high-speed shaft (HSS. A comparison of the impact on the drive train is made for two converter control strategies during small voltage dips. Through the analysis of torque, speed and tower vibration, the results indicate that both power recovery speed and the sudden torque sag have a significant impact on drive trains, and the effects depend on the different control strategies. Moreover, resonance might be excited on the drive train by an unbalanced voltage.

  12. A new emergency control for voltage stability utilizing the time overvoltage capability of large shunt capacitor banks

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Carson W.; Vanleuven, Allen L.; Nordstrom, Jerry M. [Bonneville Power Administration, Portland, OR (United States)

    1994-12-31

    Electric utilities have become increasing concerned with the possibility of voltage instability and voltage collapse. Although many countermeasures are a possible, control based countermeasures are often the most cost effective. Voltage collapse is often only a threat during unusual conditions such as very high load and major outages. For these low probability conditions, low cost emergency controls may be the only cost effective countermeasures. This paper provides details on a prototype installation by the Bonneville Power Administration of a new low cost emergency control for voltage stability named CAPS (CAPacitor bank series group Shorting). (author) 6 refs., 5 figs.

  13. 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

    currents injected to the grid. Furthermore, the respective PI-R controller in the positive synchronous reference frame for the SGSC voltage control and PGSC current control have been developed to achieve precise and rapid regulation of the corresponding components. Finally, the proposed coordinated control......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...... 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...

  14. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    In this paper, a combinational AC/DC power flow approach is proposed for the solution of the combined AC/DC network. The unified power flow approach is extended to include DC voltage droop control. In the VSC based MTDC grids, DC droop control is regarded as more advantageous in terms...... of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  15. Protecting a Diamond Quantum Memory by Charge State Control.

    Science.gov (United States)

    Pfender, Matthias; Aslam, Nabeel; Simon, Patrick; Antonov, Denis; Thiering, Gergő; Burk, Sina; Fávaro de Oliveira, Felipe; Denisenko, Andrej; Fedder, Helmut; Meijer, Jan; Garrido, Jose A; Gali, Adam; Teraji, Tokuyuki; Isoya, Junichi; Doherty, Marcus William; Alkauskas, Audrius; Gallo, Alejandro; Grüneis, Andreas; Neumann, Philipp; Wrachtrup, Jörg

    2017-09-11

    In recent years, solid-state spin systems have emerged as promising candidates for quantum information processing. Prominent examples are the nitrogen-vacancy (NV) center in diamond, phosphorus dopants in silicon (Si:P), rare-earth ions in solids, and VSi-centers in silicon-carbide. The Si:P system has demonstrated that its nuclear spins can yield exceedingly long spin coherence times by eliminating the electron spin of the dopant. For NV centers, however, a proper charge state for storage of nuclear spin qubit coherence has not been identified yet. Here, we identify and characterize the positively charged NV center as an electron-spin-less and optically inactive state by utilizing the nuclear spin qubit as a probe. We control the electronic charge and spin utilizing nanometer scale gate electrodes. We achieve a lengthening of the nuclear spin coherence times by a factor of 4. Surprisingly, the new charge state allows switching of the optical response of single nodes facilitating full individual addressability.

  16. Analysis of electric field control methods for foil coils in high-voltage linear actuators

    Directory of Open Access Journals (Sweden)

    Beek T.A. van

    2015-12-01

    Full Text Available This paper describes multiple electric field control methods for foil coils in high-voltage coreless linear actuators and their sensitivity to misalignment. The investigated field control methods consist of resistive, refractive, capacitive and geometrical solutions for mitigating electric stress at edges and corners of foil coils. These field control methods are evaluated using 2-D boundary element and finite element methods. A comparison is presented between the field control methods and their ability to mitigate electric stress in coreless linear actuators. Furthermore, the sensitivity to misalignment of the field control methods is investigated.

  17. Robust Current Control of Doubly Fed Wind Turbine Generator under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Wang, Yun; Gong, Wenming; Wu, Qiuwei

    2014-01-01

    This paper presents the design of a H ∞ current controller for doubly fed induction generators (DFIGs) in order to maintain stable operation under unbalanced voltage conditions. The H ∞ current controller has a multi-input and multi-output (MIMO) structure and is designed using the loop shaping...... method. Case studies have been carried out in order to verify the efficacy of the proposed H ∞ current controller for DFIGs. The case study results show that the proposed H ∞ current controller can realize different control objectives, i.e. stable stator current, stable stator active power and stable...

  18. Design of a constant-voltage and constant-current controller with dual-loop and adaptive switching frequency control

    Science.gov (United States)

    Yingping, Chen; Zhiqian, Li

    2015-05-01

    A 5.0-V 2.0-A flyback power supply controller providing constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed here due to its better regulation performance of tolerance over process and temperature compared with open loop control used in common. At the same time, the two modes, CC and CV, could switch to each other automatically and smoothly according to the output voltage level not sacrificing the regulation accuracy at the switching phase, which overcomes the drawback of the digital control scheme depending on a hysteresis comparator to change the mode. On-chip compensation using active capacitor multiplier technique is applied to stabilize the voltage loop, eliminate an additional package pin, and save on the die area. The system consumes as little as 100 mW at no-load condition without degrading the transient response performance by utilizing the adaptive switching frequency control mode. The proposed controller has been implemented in a commercial 0.35-μm 40-V BCD process, and the active chip area is 1.5 × 1.0 mm2. The total error of the output voltage due to line and load variations is less than ±1.7%.

  19. Two distinct voltage-sensing domains control voltage sensitivity and kinetics of current activation in CaV1.1 calcium channels.

    Science.gov (United States)

    Tuluc, Petronel; Benedetti, Bruno; Coste de Bagneaux, Pierre; Grabner, Manfred; Flucher, Bernhard E

    2016-06-01

    Alternative splicing of the skeletal muscle CaV1.1 voltage-gated calcium channel gives rise to two channel variants with very different gating properties. The currents of both channels activate slowly; however, insertion of exon 29 in the adult splice variant CaV1.1a causes an ∼30-mV right shift in the voltage dependence of activation. Existing evidence suggests that the S3-S4 linker in repeat IV (containing exon 29) regulates voltage sensitivity in this voltage-sensing domain (VSD) by modulating interactions between the adjacent transmembrane segments IVS3 and IVS4. However, activation kinetics are thought to be determined by corresponding structures in repeat I. Here, we use patch-clamp analysis of dysgenic (CaV1.1 null) myotubes reconstituted with CaV1.1 mutants and chimeras to identify the specific roles of these regions in regulating channel gating properties. Using site-directed mutagenesis, we demonstrate that the structure and/or hydrophobicity of the IVS3-S4 linker is critical for regulating voltage sensitivity in the IV VSD, but by itself cannot modulate voltage sensitivity in the I VSD. Swapping sequence domains between the I and the IV VSDs reveals that IVS4 plus the IVS3-S4 linker is sufficient to confer CaV1.1a-like voltage dependence to the I VSD and that the IS3-S4 linker plus IS4 is sufficient to transfer CaV1.1e-like voltage dependence to the IV VSD. Any mismatch of transmembrane helices S3 and S4 from the I and IV VSDs causes a right shift of voltage sensitivity, indicating that regulation of voltage sensitivity by the IVS3-S4 linker requires specific interaction of IVS4 with its corresponding IVS3 segment. In contrast, slow current kinetics are perturbed by any heterologous sequences inserted into the I VSD and cannot be transferred by moving VSD I sequences to VSD IV. Thus, CaV1.1 calcium channels are organized in a modular manner, and control of voltage sensitivity and activation kinetics is accomplished by specific molecular mechanisms

  20. A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

    Science.gov (United States)

    Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

    2016-03-01

    Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results.