Optimal Design of Modern Transformerless PV Inverter Topologies
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
The design optimization of H5, H6, neutral point clamped, active-neutral point clamped, and conergy-NPC transformerless photovoltaic (PV) inverters is presented in this paper. The components reliability in terms of the corresponding malfunctions, affecting the PV inverter maintenance cost during...... the operational lifetime period of the PV installation, is also considered in the optimization process. According to the results of the proposed design method, different optimal values of the PV inverter design variables are derived for each PV inverter topology and installation site. The H5, H6, neutral point...... clamped, active-neutral point clamped and conergy-NPC PV inverters designed using the proposed optimization process feature lower levelized cost of generated electricity and lifetime cost, longer mean time between failures and inject more PV-generated energy into the electric grid than their nonoptimized...
Modified Multilevel Inverter Topology for Grid Connected Pv Systems
Directory of Open Access Journals (Sweden)
Dhivya Balakrishnan
2013-10-01
Full Text Available Multilevel converters offer high power capability, associated with lower output harmonics and lower commutation losses. Their main disadvantage is their complexity, requiring a great number of power devices and passive components, and a rather complex control circuitry. This paper proposes a single-phase seven- level inverter for grid connected PV systems, with a novel pulse width-modulated (PWM control scheme. Three reference signals that are identical to each other with an offset that is equivalent to the amplitude of the triangular carrier signal were used to generate the PWM signals. The inverter is capable of producing seven levels of output-voltage levels from the dc supply voltage. This paper proposes a new multilevel inverter topology using an H-bridge output stage with two bidirectional auxiliary switches. The new topology produces a significant reduction in the number of power devices and capacitors required to implement a multilevel output using the Asymmetric Cascade configuration.
The high efficiency transformer-less PV inverter topologies derived from NPC topology
DEFF Research Database (Denmark)
Ma, Lin; Kerekes, Tamas; Teodorescu, Remus;
2009-01-01
The grid-connected photovoltaic (PV) systems are an important part of renewable energy sources and their integration is getting more and more widespread. In order to improve the efficiency, practicality and reliability of the PV systems, many kinds of new inverter topologies have been proposed...... to avoid using a grid isolation transformer. The NPC topology and two other derived topologies are presented and analyzed in this paper. Validated by experiments, it has been proven that they are very suitable for using in transformer-less PV applications due to high efficiency, low leakage current and EMI...
A new high-efficiency single-phase transformerless PV inverter topology
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Rodriguez, Pedro;
2011-01-01
There is a strong trend in the photovoltaic (PV) inverter technology to use transformerless topologies in order to acquire higher efficiencies combining with very low ground leakage current. In this paper a new topology, based on the H-Bridge with a new AC bypass circuit consisting in a diode rec...
Analysis of Leakage Current and DC Injection in Transformerless PV Inverter Topologies
Directory of Open Access Journals (Sweden)
Anjali Varghese C
2014-03-01
Full Text Available Considering low efficiencies of solar panels, the reliability and efficiency of power electronic interface has to be ensured. Transformerless PV inverters increases the efficiency by nearly 2% and decreases cost by 25%. With no galvanic isolation comes the problem of dc injection and ground leakage current which pauses serious problems to core saturation of distribution transformers, cable corrosion, Power quality and EMI problems and has to be limited as per IEEE standards. This paper gives an analysis of leakage current flowing through the parasitic capacitance and also the DC injection in the output of the inverter. Analysis is done for various values of parasitic capacitance. Five different HBridge derived topologies and PWM techniques are evaluated on the basis of leakage current and DC injection.
Directory of Open Access Journals (Sweden)
M. N. H. Khan
2015-03-01
Full Text Available The Photovoltaic (PV is a part and parcel and well known for cost-effective and easy to operatefeatures when it is used with transformer-less inverter-based grid-tied distribution generation systems. It reduces the leakage current issue that actually occurs making paths from PV penal to ground. In this paper has been addressed this issue as main problem for reducing leakage current. Moreover, here iscompared the proposed topology’s results to AC and DC-based transformer-less topologies. The possibilities of larger number of leakage current paths indicatepower loss, which is the focus of work in this paper for different switching conditions. The results on leakage current paths using PSpice with different parasitic capacitance values from inverters of different topologies are compared with the simulation results of the topology proposed in this paper.
Common mode behavior in grid connected DC and AC decoupled PV Inverter topologies
Directory of Open Access Journals (Sweden)
Sundar D. John
2016-09-01
Full Text Available The transformer-less grid connected inverters are gaining more popularity due to their high efficiency, very low ground leakage current and economic feasibility especially in photovoltaic systems. The major issue which surfaces these systems is that of common mode leakage current which arises due to the absence of an electrical transformer connected between the inverter and the utility grid. Several topologies have evolved to reduce the impact of common mode leakage current and a majority of them have succeeded in eliminating the impacts and have well kept them within the limits of grid standards. This paper compares and analyses the impact of the common mode leakage current for four popular inverter configurations through simulation of the topologies such as H5, H6, HERIC and FBZVR inverters.
Soft-switching Grid-connected PV Inverter With Interleaved Flyback Topology
Institute of Scientific and Technical Information of China (English)
2011-01-01
The flyback topology has advantages of robustness and low cost and is proposed for 200-300 W class grid-connected photovoltaic inverter. However, the flyback converter is known for its low efficiency and low resolution control. Therefore, digitalized soft switching technique and algorithm are to be developed.
Leakage current measurement in transformerless PV inverters
DEFF Research Database (Denmark)
Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo
2012-01-01
to be used in commercial PV inverters for the measurement of leakage and fault ground currents. The German VDE0126–1–1 standard gives the limit for fault and leakage ground currents and all grid connected PV inverters have to comply with these limits and disconnect from the grid in case of a fault.......Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...
High-efficiency Transformerless PV Inverter Circuits
Chen, Baifeng
2015-01-01
With worldwide growing demand for electric energy, there has been a great interest in exploring photovoltaic (PV) sources. For the PV generation system, the power converter is the most essential part for the efficiency and function performance. In recent years, there have been quite a few new transformerless PV inverters topologies, which eliminate the traditional line frequency transformers to achieve lower cost and higher efficiency, and maintain lower leakage current as well. With an ov...
DEFF Research Database (Denmark)
Anthon, Alexander
their trade-offs. The contributions are: • Comprehensive loss analysis and identification of major loss contributors within T-Type converter topology operating in inverter and rectifier context. • Evaluation of the use and loss benefits of Silicon Carbide switching devices in the T-Type structure...... and new approaches are necessary. Therefore, research areas typically focus on both new topologies and utilizing more advanced semiconductor devices. To this end, semiconductor devices made of Silicon Carbide have been gaining increasing interest in the last two decades after the successful...... commercialization of high voltage power diodes. By now, the performance potential of switching devices made of Silicon Carbide is commonly accepted, though they have not found commonplace usage within commercial converter systems for several reasons, among others reliability, availability/cost and gate driver...
Directory of Open Access Journals (Sweden)
Sandhya Seelam
2015-08-01
Full Text Available MATLABbasedsingle-phase three-level topology for a transformer less photovoltaic system is presented in this paper. Compared with the conventional H-bridge topology, it only needs two additional asymmetrically distributed switches, and the system common-mode voltage can be kept constant with a simple modulation scheme. Family of H6 transformer less inverter topologies with low leakage currents is proposed and highly efficient and reliable inverter concept (HERIC topology is also presented in this paper. The proposed inverter can also operate with high frequency by retaining high efficiency which enables reduced cooling system. Finally, the proposed new topology is simulated by MATLAB/Simulink software to validate the accuracy of the theoretical explanation.
DEFF Research Database (Denmark)
Paasch, Kasper; Nymand, Morten; Kjær, Søren Bækhøj
2015-01-01
MPPT) and a series of small central inverters (60 kW, 1 MPPT) in the same PV plant under varying irradiation conditions and also including the potential detrimental effect of the horizontally tilt of the solar panels due to area topography variation. It has been shown that the gain from using multiple...
DEFF Research Database (Denmark)
Paasch, Kasper; Nymand, Morten; Kjær, Søren Bækhøj
2015-01-01
MPPT) and a series of small central inverters (60 kW, 1 MPPT) in the same PV plant under varying irradiation conditions and also including the potential detrimental effect of the horizontally tilt of the solar panels due to area topography variation. It has been shown that the gain from using multiple...
Transformerless PV inverters. Final report
Energy Technology Data Exchange (ETDEWEB)
Borup, U.
2009-12-15
Since the start of the project the market for grid connected PV inverters have developed further. When the project started three - phase inverter were only available in high power systems. The technology developed within this project will enable three phase technology also to be implemented in string inverters for system down to 10 kW. We expect this to be very attractive due to the increased demand for symmetrical feed-in to the grid. The project relevance is therefore high and the sector continues to develop very much driven by technology. Especially the inverter technology is getting a lot of focus. The inverter systems are expected to take a much larger role in supporting the electrical grid in the future. The technology platform developed within the project is prepared to be extended with these utility functionalities. The main results of the project were: 1) A new technology concept for transformer-less inverters has been demonstrated with a number of prototypes. 2) Efficiency above 97,7% has been proven. 3) Efficiency and Maximum power point tracking has been optimized to ensure that almost all energy produced of the panels is transferred to the grid. 4) The platform is developed with a very fast control board, which enables extended functionality as demanding grid supporting functions in the future. Details about cost price and details about the control loop implementation is excluded from the report due to the competitive situation for Danfoss Solar Inverters A/S. (LN)
Robustness analysis of the efficiency in PV inverters
DEFF Research Database (Denmark)
Pigazo, Alberto; Liserre, Marco; Blaabjerg, Frede;
2013-01-01
During last years an increasing attention has been paid to the efficiency of grid-connected PV inverters. They are manufactured from a number of discrete components and by using a certain topology and control strategy. Hence, the performance of a certain PV inverter not only depends on the selected...... topology and control strategy but also on the characteristics of the employed components. The aim of this paper is evaluate the effect of physical variations associated to the main components on the overall efficiency of PV inverters. It is concluded that a statistical evaluation of the power converter...... provides a better understanding of the PV inverter performance and, in this sense, the definition of the European Efficiency must be reviewed in order to show the quality of the manufactured product....
Optimal design of NPC and Active-NPC transformerless PV inverters
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2012-01-01
Targeting at a cost-effective deployment of grid-connected PhotoVoltaic (PV) systems, this paper presents a new methodology for the optimal design of transformerless PV inverters, which are based on the Neutral Point Clamped (NPC) and the Active-Neutral Point Clamped (ANPC) topologies. The design...... optimization results demonstrate that a different set of optimal values of the PV inverter switching frequency and output filter components are derived for the NPC and ANPC topologies, respectively, as well as for each of the PV inverter installation sites under study. The NPC and ANPC PV inverter structures...
Online Variable Topology-Type Photovoltaic Grid-Connected Inverter
DEFF Research Database (Denmark)
Wu, Fengjiang; Sun, Bo; Duan, Jiandong
2015-01-01
and H-bridge inverter under the conditions of variable output voltage and power of the PV array. It is proved that, compared with the H-bridge inverter, the operation range of the cascaded inverter is wider, whereas the total loss is larger. Furthermore, a novel online variable topology-type grid...
Soft-switching Grid-connected PV Inverter With Interleaved Flyback Topology%软开关交错反激光伏并网逆变器
Institute of Scientific and Technical Information of China (English)
古俊银; 吴红飞; 陈国呈; 邢岩
2011-01-01
A soft-switching grid-connected PV inverter topology with its soft-switching algorithm was proposed. Leak inductance energy is recovered and the drain-source voltage of the main switch is clamped with the help of the leak inductance energy recovery circuit to improve the conversion efficiency and eliminate the switch-off voltage spike of the main switch. A DSP-based resonant soft-switching algorithm with variable switching frequency was proposed to achieve zero voltage switching （ZVS） turning-on of the main switch and improve the electromagnetic interference （EMI） performance of the inverter. The interleaved flyback topology reduces the volume of the transformer and filtering inductor, and improves the power density of the inverter. In-depth analysis was given on the inverter principles and the principle and criteria of variable resonant soft-switching algorithm. Finally, experimental results were given.%提出一种应用于单个光伏组件的软开关交错反激并网逆变器拓扑及其软开关控制策略。针对反激变压器漏感问题，提出漏感能量吸收回馈电路，实现了漏感能量吸收再利用，并实现了开关管漏源电压的钳位，提高了变换效率同时降低了开关管关断电压尖峰；提出基于数字处理器的反激变换器变开关频率谐振软开关控制策略，实现了开关管的零电压开通，同时改善了逆变器的电磁兼容特性；提出的交错并联反激逆变器有助于减小变压器和滤波器的体积，提高功率密度。详细分析变换器的工作原理，分析变开关频率谐振软开关控制方式的原理和实现条件，最后进行实验验证。
Invertibility in L-Topological Spaces
Directory of Open Access Journals (Sweden)
Anjaly Jose
2014-03-01
Full Text Available In this paper, we extend the concept of invertibility to L-topological spaces and delineate its properties. Then, we study further completely invertible L-topological spaces and introduce two types of invertible L-topologies based on the inverting maps, studying their sums, subspaces and simple extensions.
Advancement in solar PV Inverter
Directory of Open Access Journals (Sweden)
Devendra Doda
2012-09-01
Full Text Available This teardown article will delve into the architectural design and components of a solar inverter card starting from the Solar panel DC inputs and working through the DC to AC conversion process to the AC output that is sent out to the power grid. Features needed to be implemented into such a design to meet various safety and other performance standards as well as stringent power company demands upon the signal that is put onto their grid will be shown. In the process, major elements and component choices made in the design of the series of solar inverters, from the EMI suppression capacitors with a special emphasis on isolation and protection, through the smart use of optically isolated MOSFETgatedrivers.
Modeling Single-Phase PV HB-ZVR Inverter Connected to Grid
DEFF Research Database (Denmark)
Guo, Yougui; Zeng, Ping; Zhu, Jieqiong;
2011-01-01
PLECS is used to model the PV H-bridge zero voltage rectifier (HB-ZVR) inverter connected to grid and good results are obtained. First, several common topologies of PV inverters are introduced. Then the unipolar PWM control strategy is described for PV HB-ZVR inverter. Third, PLECS is briefly...... introduced. Fourth, the modeling of PV HB-ZVR inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is very powerful tool to real power circuits and it is very easy to simulate LCL filter. They have also verified that the unipolar PWM control...... strategy is feasible to control the PV HB-ZVR inverter....
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....
H6 Non-isolated Full Bridge Grid-connected PV Inverters With Low Leakage Currents
Institute of Scientific and Technical Information of China (English)
ZHANG Li; SUN Kai; FENG Lanlan; XING Yan; XU Ming
2012-01-01
Non-isolated inverter topologies have obtained more attentions in photovoltaic （PV） generation system since they are featured by higher efficiency and lower cost. In order to meet the safety requirement for the non-isolated grid-tied PV inverter, the common-mode leakage current is required to be carefully tackled due to the absence of the transformer. A H6 non-isolated full bridge PV grid-connected inverter is proposed to meet the limit for common-mode leakage current in grid-tied PV generation systems, as shown in Fig. 1.
Design optimization of grid-connected PV inverters
DEFF Research Database (Denmark)
Koutroulis, Eftichios; Blaabjerg, Frede
2011-01-01
The DC/AC inverters are the key elements in grid-connected PV energy production systems. In this paper, new design optimization techniques focused on transformerless (very high efficiency) PV inverters are proposed. They have been developed based on an analysis of the deficiencies of the current......, state-of-the-art PV inverters design technology, which limits the amount of PV energy supplied into the electric grid. The influences of the electric grid regulations and standards and the PV array operational characteristics on the design of grid-connected PV inverters have also been considered....... The simulation results verify that the proposed optimization techniques enable the maximization of the PV energy injected into the electric grid by the optimized PV installation....
Institute of Scientific and Technical Information of China (English)
肖华锋; 杨晨; 谢少军
2011-01-01
The unipolar sine pulse width modulation (SPWM) full-bridge inverter brings about common-mode voltage with high frequency, which restricts the application in transformerless PV grid-connected inverters. In order to solve this problem, an improved full-bridge structure with two switches and capacitance divider was proposed to guarantee that the freewheel path is clamped to the half input voltage in freewheel period. Thus, the common-mode voltage with high frequency can be eliminated in unipolar SPWM. The operation mode and the clamping mode were analyzed, and the total losses of power devices for the proposed topology and several existed topologies were calculated. Finally, the common-mode performance of these topologies was verified with a universal prototype inverter rated at 1 kW.%单极性正弦脉宽调制(sine pulse width modulation,SPWM)全桥逆变器存在高频脉动的共模电压,限制了它在非隔离型单相并网逆变器中的使用.为解决此问题,提出一种改进型全桥电路结构,在全桥电路输入侧引入两支有源开关管和分压电容组来实现伞桥变换器续流阶段时续流回路电位的可靠钳位,从而在保证单极性SPWM全桥电路筹模特性的前提下消除了高频脉动的共模电压.详细分析新型逆变器的工作模态和箝位模态,计算几种常用拓扑和提出拓扑的功率器件损耗,并通过一台1 kw通用样机平台对比验证这几种拓扑的共模特性.
A review of module inverter topologies suitable for photovoltaic system
DEFF Research Database (Denmark)
Variath, Reshmi C; Andersen, Michael A. E.; Nielsen, Ole Neis
2010-01-01
This paper evaluates eight module inverter topologies and provides an overview of the merits and demerits of each on the basis of circuit level Pspice simulation. The complete system is modeled in Pspice and the model is made as realistic as possible by including the parasitic elements. Only...... the output stage is varied for different topologies keeping the system model unaltered with the same control system and degree of demodulation so as to differentiate the variation of efficiency of these topologies. The purpose of the analysis is to determine which of this topology would be a best fit...... for the system and what are the compromises to be made (if any) to select one of these topologies as the output stage in the PV system....
Z - Source Multi Level Inverter Based PV Generation System
Directory of Open Access Journals (Sweden)
T. Lakhmi kanth
2014-09-01
Full Text Available In this paper a novel technique of Z-Source multilevel Inverter based PV Generation system is implemented and simulated using MATLAB-Simulink simulation software. The Photovoltaic cells are healthier option for converting solar energy into electricity. Due to high capital cost and low efficiency PV cells have not yet been a fully smart choice for electricity users. To enhance the performance of the system, Z-Source multi level inverter can be used in place of conventional Voltage Source Inverter (VSI in Solar Power Generation System. The PV cell model is developed using circuit mathematical equations. The Z-Source multilevel inverter is modeled to realize boosted DC to AC conversion (inversion with low THD. Outcome shows that the energy conversion efficiency of ZSMLI is a lot improved as compared to conventional voltage Source Inverter (VSI. By doing FFT analysis we can know the total THD.
2016-01-01
This paper presents a modular cascaded H-bridge multilevel photovoltaic (PV) inverter for three-phase grid-connected applications. The modular cascaded multilevel topology helps to improve the efficiency and flexibility of PV systems. The main abstruse is the harmonization of the DG to the utility grid. Generally current regulated PWM voltage-source inverters (VSI) are used for synchronizing the utility grid with DG source in order to meet the following objectives: 1) To ensure grid stability...
Hybrid PV/wind system with quinary asymmetric inverter without increasing DC-link number
Directory of Open Access Journals (Sweden)
Aida Baghbany Oskouei
2016-06-01
Full Text Available This paper suggests quinary asymmetric inverter with coupled inductors and transformer, and uses it in hybrid system including photovoltaic (PV and wind. This inverter produces twenty-five-level voltage in addition to merits of multilevel inverter, has only one DC source. Then, it is adequate for hybrid systems, which prevents increasing DC-link and makes control of system easy. Proposed structure also provides isolation in the system and the switch numbers are reduced in this topology compared with other multilevel structures. In this system, battery is used as backup, where PV and wind have complementary nature. The performance of proposed inverter and hybrid system is validated with simulation results using MATLAB/SIMULINK software and experimental results based PCI-1716 data acquisition system.
Review of PV Inverter Technology Cost and Performance Projections
Energy Technology Data Exchange (ETDEWEB)
Navigant Consulting Inc.
2006-01-01
The National Renewable Energy Laboratory (NREL) has a major responsibility in the implementation of the U.S. Department of Energy's (DOE's) Solar Energy Technologies Program. Sandia National Laboratories (SNL) has a major role in supporting inverter development, characterization, standards, certifications, and verifications. The Solar Energy Technologies Program recently published a Multiyear Technical Plan, which establishes a goal of reducing the Levelized Energy Cost (LEC) for photovoltaic (PV) systems to $0.06/kWh by 2020. The Multiyear Technical Plan estimates that, in order to meet the PV system goal, PV inverter prices will need to decline to $0.25-0.30 Wp by 2020. DOE determined the need to conduct a rigorous review of the PV Program's technical and economic targets, including the target set for PV inverters. NREL requested that Navigant Consulting Inc.(NCI) conduct a review of historical and projected cost and performance improvements for PV inverters, including identification of critical barriers identified and the approaches government might use to address them.
Design optimization of transformerless grid-connected PV inverters including reliability
DEFF Research Database (Denmark)
Koutroulis, Eftichios; Blaabjerg, Frede
2012-01-01
This paper presents a new methodology for optimal design of transformerless Photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal values and types of the PV inverter components are calculated such that the PV inverter Levelized Cost Of the Ele......This paper presents a new methodology for optimal design of transformerless Photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal values and types of the PV inverter components are calculated such that the PV inverter Levelized Cost...... to the non-optimized PV inverter structures, the PV inverters designed using the proposed optimization methodology exhibit lower total manufacturing and lifetime maintenance cost and inject more energy into the electric-grid and by that minimizing LCOE....
Optimization of PV-based energy production by dynamic PV-panel/inverter configuration
DEFF Research Database (Denmark)
Paasch, Kasper; Nymand, Morten; Haase, Frerk
This paper investigates the possible increase in annual energy production of a PV system with more than one MPPT (maximum power point tracker) input channels under Nordic illumination conditions, in case a concept of dynamic switching of the PV panels is used at the inputs of the inverters....
Directory of Open Access Journals (Sweden)
Anjali Varghese C
2013-08-01
Full Text Available The necessity of efficient topologies for photovoltaic (PV inverters is a concern presently. With the advent of transformerless inverters, the size, volume and cost of PV inverters can be decreased. Efficiency can be increased nearly by 2% by avoiding the galvanic connection. With no galvanic isolation comes the problem of dc injection which pauses serious problems to core saturation of distribution transformers and cable corrosion and has to be limited as per IEEE, IEC standards. This paper presents a proportional resonant controller and is used along with a modelled series capacitance to limit DC injection. This avoids the use of a real capacitor in the output of the inverter used conventionally toprevent dc injection and hence overcomes the drawbacks of series voltage drops and reverse polarity effects. The topology of inverter chosen is the H-Bridge and switching scheme used is unipolar PWMconsidering the advantages of the same . A comparison of the dc injection values with and without the controller is presented for unipolar pulse width modulated (PWM inverters.
Control of Single-Stage Single-Phase PV inverter
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented....... The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter....
Reliability Assessment of Transformerless PV Inverters considering Mission Profiles
Directory of Open Access Journals (Sweden)
Yongheng Yang
2015-01-01
Full Text Available Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved by either modifying the modulation schemes or adding extra power switching devices, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redistributed and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device reliability of three transformerless inverters under a yearly mission profile (i.e., solar irradiance and ambient temperature. The mission profile is translated to device thermal loading, which is used for lifetime prediction. Comparison results reveal the lifetime mismatches among the power switching devices operating under the same condition, which offers new thoughts for a robust design and a reliable operation of grid-connected transformerless PV inverters with high efficiency.
Common mode voltage in case of transformerless PV inverters connected to the grid
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco
2008-01-01
For safety reasons grid connected PV systems include galvanic isolation. In case of transformerless inverters, the leakage ground current through the parasitic capacitance of the PV panels, can reach very high values. A common-mode model based on analytical approach is introduced, used to predict...... the common-mode behavior, at frequencies lower than 50kHz, of the selected topologies and to explain the influence of system imbalance on the leakage current. It will be demonstrated that the neutral inductance has a crucial influence on the leakage current. Finally experimental results will be shown...
Reliability Assessment of Transformerless PV Inverters Considering Mission Profiles
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2015-01-01
, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redis-tributed, and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device......Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved either by modifying the modulation schemes or adding extra power switching devices...... devices operating under the same condition, which offers new thoughts for a robust design and a reliable operation of grid-connected transformerless PV inverters with high efficiency....
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
Single-phase transformerless Photovoltaic (PV) inverters are synthesized by combining available solutions in terms of the power section topology, power semiconductors manufacturing technology and structure of the output filter. A design method is presented in this paper for optimizing the power s...
Energy Technology Data Exchange (ETDEWEB)
Hoke, Anderson [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, Brian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bell, Frances [SolarCity, San Mateo, CA (United States); McCarty, Michael [SolarCity, San Mateo, CA (United States)
2016-07-01
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1.) In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2.) The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in this report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called 'solar subdivision' scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters. This was accomplished through the use of power hardware-in-the-loop (PHIL) simulation, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. The anti-islanding test design was a modified version of the unintentional islanding test in IEEE Standard 1547.1, which creates a balanced, resonant island with the intent of creating a highly challenging condition for island detection. Three common, commercially available single-phase PV inverters from three different manufacturers were tested. The first part of this work examined each inverter individually using a series of pure hardware resistive-inductive-capacitive (RLC
Application ofBoost Inverter to Multi Input PV system
Directory of Open Access Journals (Sweden)
G.SHINYVIKRAM
2014-11-01
Full Text Available With the shortage of the energy and ever increasing of the oil price, research on the renewable and green energy sources, especially the solar arrays and the fuel cells, becomes more and more important. How to achieve high step- up and high efficiency DC/DC converters is the major consideration in the renewable power applications due to the low voltage of PV arrays and fuel cells. The conventional boost converters increase the harmonics rate and add an extra stage of power conversion. This paper proposes a boost dc-ac inverter that can invert and boost the output voltage in a single stage. In this paper the proposed boost dc-ac inverter is applied to the solar power panels and is simulated using Simulink. The output results of the boost inverter are worthy promising.
Design Optimization of Transformerless Grid-Connected PV Inverters Including Reliability
DEFF Research Database (Denmark)
Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated such that......This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated...... that compared to the nonoptimized PV inverter structures, the PV inverters designed using the proposed optimization methodology exhibit lower total manufacturing and lifetime maintenance cost and inject more energy into the electric-grid and by that minimizing LCOE....
Lifetime Evaluation of PV Inverters considering Panel Degradation Rates and Installation Sites
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso
2017-01-01
The PV inverter lifetime is affected by the installed sites related to different solar irradiance and ambient temperature profiles. In fact, the installation site also affects the PV panel degradation rate, and thus the long-term power production. Prior-art lifetime analysis in PV inverters has...... not yet investigated the impact of panel degradation. This paper thus evaluates the lifetime of PV inverters considering panel degradation rates and installation sites. Evaluations have been carried out on PV systems installed in Denmark and Arizona. The results reveal that the PV panel degradation rate...... has a considerable impact on the PV inverter lifetime, especially in the hot climate (e.g., Arizona), where the panel degrades at a faster rate. In that case, the PV inverter lifetime estimation can be deviated by 54%, if the impact of PV panel degradation is not taken into account....
Methods for the Optimal Design of Grid-Connected PV Inverters
DEFF Research Database (Denmark)
Koutroulis, Eftichios; Blaabjerg, Frede
2011-01-01
and the efficient processing of this power by the DC/AC inverter. In this paper two new methods are presented for the optimal design of a PV inverter power section, output filter and MPPT control strategy. The influences of the electric grid regulations and standards as well as the PV array operational......The DC/AC inverters are used in grid-connected PV energy production systems as the power processing interface between the PV energy source and the electric grid. The energy injected into the electric grid by the PV installation depends on the amount of power extracted from the PV power source...... characteristics on the design of grid-connected PV inverters have been considered. The proposed methods have been applied for the optimal design of PV inverters installed at various sites in Europe. The simulation results verify that the proposed optimization techniques enable the maximization of the PV energy...
Transformerless Topology for Grid-Conected Inverters With Unipolar PWM Control
Directory of Open Access Journals (Sweden)
N.SivaPrasad
2014-10-01
Full Text Available Most of the PV systems are designed with transformer for safety purpose with galvanic isolation. However, the transformer is big, heavy and expensive. Also, it reduces the overall frequency of the conversion stage. Generally PV inverter with transformer is having good efficiency. To overcome these problems, transformer less PV system is introduced. It is smaller, lighter, cheaper and higher in efficiency. However, dangerous leakage current will flow between PV array and the grid due to the stray capacitance. There are different types of configurations available for transformer less inverters like H5, H6, HERIC, and Dual paralleled buck inverter. But each configuration is suffering from its own disadvantages like high conduction losses, shoot-through issues of switches, dead-time requirements at zero crossing instants of grid voltage to avoid grid shoot-through faults and MOSFET reverse recovery issues. The main objective of the proposed transformer less inverter is to address two key issues: One key issue for a transformer less inverter is that it is necessary to achieve high efficiency compared to other existing inverter topologies. Another key issue is that the inverter configuration should not have any shoot-through issues for higher reliability.
Directory of Open Access Journals (Sweden)
Gianluca Brando
2016-09-01
Full Text Available In the context of grid connected photovoitaic (PV generation systems, there are two paramount aspects regarding the Maximum Power Point Tracking (MPPT of the photovoltaic units and the continuity of the service. The most diffused MPPT algorithms are based on either perturb and observe, or on an incremental conductance approach and need both PV current and voltage measurements. Several topology reconfigurable converters are also associated with the PV plants, guaranteeing fault-tolerant features. The generation continuity can also be assured by interleaved inverters, which keep the system operating at reduced maximum power in case of failure. In this paper, an evolution of a hysteresis based MPPT algorithm is presented, based on the measurement of only one voltage, together with a novel space vector modulation suitable for a two-channel three-phase grid connected interleaved inverter. The proposed MMPT algorithm and modulation technique are tested by means of several numerical analyses on a PV generation system of about 200 kW maximum power. The results testify the validity of the proposed strategies, showing good performance, even during a fault occurrence and in the presence of deep shading conditions.
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso
2017-01-01
Lifetime of PV inverters is affected by the installation sites related to different solar irradiance and ambient temperature profiles (also referred to as mission profiles). In fact, the installation site also affects the degradation rate of the PV panels, and thus long-term energy production...... and reliability. Prior-art lifetime analysis in PV inverters has not yet investigated the impact of PV panel degradations. This paper thus evaluates the lifetime of PV inverters considering panel degradation rates and mission profiles. Evaluations have been carried out on PV systems installed in Denmark...
Ghoudelbourk, Sihem.; Dib, D.; Meghni, B.; Zouli, M.
2017-02-01
The paper deals with the multilevel converters control strategy for photovoltaic system integrated in distribution grids. The objective of the proposed work is to design multilevel inverters for solar energy applications so as to reduce the Total Harmonic Distortion (THD) and to improve the power quality. The multilevel inverter power structure plays a vital role in every aspect of the power system. It is easier to produce a high-power, high-voltage inverter with the multilevel structure. The topologies of multilevel inverter have several advantages such as high output voltage, lower total harmonic distortion (THD) and reduction of voltage ratings of the power semiconductor switching devices. The proposed control strategy ensures an implementation of selective harmonic elimination (SHE) modulation for eleven levels. SHE is a very important and efficient strategy of eliminating selected harmonics by judicious selection of the firing angles of the inverter. Harmonics elimination technique eliminates the need of the expensive low pass filters in the system. Previous research considered that constant and equal DC sources with invariant behavior; however, this research extends earlier work to include variant DC sources, which are typical of lead-acid batteries when used in system PV. This Study also investigates methods to minimize the total harmonic distortion of the synthesized multilevel waveform and to help balance the battery voltage. The harmonic elimination method was used to eliminate selected lower dominant harmonics resulting from the inverter switching action.
PV inverter test setup for European efficiency, static and dynamic MPPT efficiency evaluation
DEFF Research Database (Denmark)
Sera, Dezso; Teodorescu, Remus; Valentini, Massimo;
2008-01-01
This paper concerns the evaluation of performance of grid-connected PV inverters in terms of conversion efficiency, European efficiency, static and dynamic MPP efficiency. Semi-automated tests were performed in the PV laboratory of the Institute of Energy Technology at the Aalborg University...... (Denmark) on a commercial transformerless PV inverter. Thanks to the available experimental test setups, that provide the required high measuring accuracy, and the developed PV simulator, which is required for MPPT performance evaluation, PV Inverters can be pretested before being tested by accredited...
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.
Optimization of SiC-based H5 and Conergy-NPC transformerless PV inverters
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
The transformerless DC/AC inverters are critical components in the rapidly growing market of grid-connected Photovoltaic (PV) applications. Also, the SiC-based power semiconductors are capable to operate reliably at high operating temperature and switches frequency levels. In this paper, a new...... profitability of the PV system....... design technique is presented for optimizing the switching frequency and structure of the LCL-type output filter in transformerless H5 and Conergy-NPC PV inverters, which employ SiC-type power devices. The design optimization results demonstrate that the optimized SiC-based PV inverters are more...
Real Time Photovoltaic Array Simulator for Testing Grid-Connected PV Inverters
DEFF Research Database (Denmark)
Sera, Dezso; Valentini, Massimo; Raducu, Alin
2008-01-01
In this paper a real time flexible PV array simulator is presented. It is a system that can simulate different PV panel arrays in specific environmental conditions. To evaluate performance of the Maximum Power Point Tracking (MPPT) of grid-connected Photovoltaic (PV) inverters only measurements...
A digital controlled PV-inverter with grid impedance estimation for ENS detection
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
of a PV-inverter with different advanced, robust control strategies and an embedded online technique to determine the utility grid impedance. By injecting an interharmonic current and measuring the voltage response it is possible to estimate the grid impedance at the fundamental frequency. The presented...... technique, which is implemented with the existing sensors and the CPU of the PV-inverter, provides a fast and low cost approach for online impedance measurement, which may be used for detection of islanding operation. Practical tests on an existing PV-inverter validate the control methods, the impedance...... measurement, and the islanding detection....
Utility-scale grid-tied PV inverter reliability workshop summary report.
Energy Technology Data Exchange (ETDEWEB)
Granata, Jennifer E.; Quintana, Michael A.; Tasca, Coryne Adelle (SRA International, Inc., Fairfax, VA); Atcitty, Stanley
2011-07-01
A key to the long-term success of the photovoltaic (PV) industry is confidence in the reliability of PV systems. Inverters are the most commonly noted cause of PV system incidents triggered in the field. While not all of these incidents are reliability-related or even necessarily failures, they still result in a loss of generated power. With support from the U.S. Department of Energy's Solar Energy Technologies Program, Sandia National Laboratories organized a Utility-Scale Grid-Tied Inverter Reliability Workshop in Albuquerque, New Mexico, January 27-28, 2011. The workshop addressed the reliability of large (100-kilowatt+) grid-tied inverters and the implications when such inverters fail, evaluated inverter codes and standards, and provided discussion about opportunities to enhance inverter reliability. This report summarizes discussions and presentations from the workshop and identifies opportunities for future efforts.
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...
Reliability Oriented Design Tool For the New Generation of Grid Connected PV-Inverters
DEFF Research Database (Denmark)
Sintamarean, Nicolae Cristian; Blaabjerg, Frede; Wang, Huai
2015-01-01
This paper introduces a reliability-oriented design tool for a new generation of grid-connected photovoltaic (PV) inverters. The proposed design tool consists of a real field mission profile (RFMP) model (for two operating regions: USA and Denmark), a PV panel model, a grid-connected PV inverter...... model, an electrothermal model, and the lifetime model of the power semiconductor devices. An accurate long-term simulation model able to consider the one-year RFMP (solar irradiance and ambient temperature) is developed. Thus, the one-year estimation of the converter device thermal loading distribution...... is achieved and is further used as an input to the lifetime model. The proposed reliability-oriented design tool is used to study the impact of mission profile (MP) variation and device degradation (aging) in the PV inverter lifetime. The obtained results indicate that the MP of the field where the PV...
Implementation and Test of an Online Embedded Grid Impedance Estimation Technique for PV Inverters
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
New and stronger power quality requirements are issued due to the increased amount of photovoltaic (PV) installations. In this paper different methods are used for continuous grid monitoring in PV inverters. By injecting a noncharacteristic harmonic current and measuring the grid voltage response...... it is possible to evaluate the grid impedance directly by the PV inverter, providing a fast and low-cost implementation. This principle theoretically provides an accurate result of the grid impedance but when using it in the context of PV integration, different implementation issues strongly affect the quality...... of the results. This paper also presents a new impedance estimation method including typical implementation problems encountered, and it also presents adopted solutions for online grid impedance measurement. Practical tests on an existing PV inverter validate the chosen solution....
Camps, Xavier; Velasco Quesada, Guillermo; Hoz Casas, Jordi de la; Martín Cañadas, María Elena
2015-01-01
This work presents a novel approach to the experimental validation of the optimal PV-to-inverter sizing ratio value for the energy yield maximization of a GCPVS by means the implementation of a custom workbench using a solar array simulator which has allowed to replicate a wide variety of technical configurations and environmental data. The compliance between the experimental setup and the mathematical model developed to simulate the optimal PV-to-inverter sizing ratio value was demonstrated ...
Effect of Reactive Power Management of PV Inverters on Need for Energy Storage
DEFF Research Database (Denmark)
Hashemi Toghroljerdi, Seyedmostafa; Østergaard, Jacob; Yang, Guangya
2013-01-01
Grid connected Photovoltaic (PV) systems are among the increasingly growing electric power generation units worldwide. The majority of new installations are expected to be residential PVs that are connected into distribution systems. However, the PV hosting capacity of low voltage (LV) grids...... is limited due to the voltage rise at the point of connection associated with the PV feed-in current. Reactive power management using PV inverters and using the electrical energy storage systems (EESS) are amongst the main solutions for increasing the PV hosting capacity in LV grids. In this paper, a method...
Final Report Report: Smart Grid Ready PV Inverters with Utility Communication
Energy Technology Data Exchange (ETDEWEB)
Seal, Brian [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Huque, Aminul [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Rogers, Lindsey [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Key, Tom [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Riley, Cameron [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Li, Huijuan [Electric Power Research Inst. (EPRI), Knovville, TN (United States); York, Ben [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Purcell, Chris [BPL Global, Inc., Canonsburg, PA (United States); Pacific, Oliver [Spirae, Inc., Fort Collins, CO (United States); Ropp, Michael [Northern Plains Power Technologies, Brookings, SD (United States); Tran, Teresa [DTE Energy, Detroit, MI (United States); Asgeirsson, Hawk [DTE Energy, Detroit, MI (United States); Woodard, Justin [National Grid, Warwick (United Kingdom); Steffel, Steve [Pepco Holdings, Inc., Washington, DC (United States)
2016-03-30
In 2011, EPRI began a four-year effort under the Department of Energy (DOE) SunShot Initiative Solar Energy Grid Integration Systems - Advanced Concepts (SEGIS-AC) to demonstrate smart grid ready inverters with utility communication. The objective of the project was to successfully implement and demonstrate effective utilization of inverters with grid support functionality to capture the full value of distributed photovoltaic (PV). The project leveraged ongoing investments and expanded PV inverter capabilities, to enable grid operators to better utilize these grid assets. Developing and implementing key elements of PV inverter grid support capabilities will increase the distribution system’s capacity for higher penetration levels of PV, while reducing the cost. The project team included EPRI, Yaskawa-Solectria Solar, Spirae, BPL Global, DTE Energy, National Grid, Pepco, EDD, NPPT and NREL. The project was divided into three phases: development, deployment, and demonstration. Within each phase, the key areas included: head-end communications for Distributed Energy Resources (DER) at the utility operations center; methods for coordinating DER with existing distribution equipment; back-end PV plant master controller; and inverters with smart-grid functionality. Four demonstration sites were chosen in three regions of the United States with different types of utility operating systems and implementations of utility-scale PV inverters. This report summarizes the project and findings from field demonstration at three utility sites.
Improved Reliability of Single-Phase PV Inverters by Limiting the Maximum Feed-in Power
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
. The CPG control strategy is activated only when the DC input power from PV panels exceeds a specific power limit. It enables to limit the maximum feed-in power to the electric grids and also to improve the utilization of PV inverters. As a further study, this paper investigates the reliability performance...... of the power devices (e.g. IGBTs) used in PV inverters with the CPG control under different feed-in power limits. A long-term mission profile (i.e. solar irradiance and ambient temperature) based stress analysis approach is extended and applied to obtain the yearly electrical and thermal stresses of the power...
Extended topologies of tapped-inductor Z-source inverters
DEFF Research Database (Denmark)
Zhu, Miao; Li, Ding; Gao, Feng
2011-01-01
into a generic network entity, which is termed hybrid-source tapped-inductor impedance network. The resulting novel Z-source inverters would have a higher output voltage gain and other unique advantages that currently have not yet been investigated. Theoretical analysis for explaining these operating features......In this paper, two distinct types of tapped-inductor Z-source impedance networks are proposed for implementing high performance voltage-type inverters topologies with strong voltage boost inversion abilities and less components' stresses. All proposed topologies can in principle be unified...
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...
Research on Modulation Strategies Based on Multilevel Inverter Universal Hybrid Topology
Institute of Scientific and Technical Information of China (English)
Zhou Jinghua; Su Yanmin; Shen Chuanwen; Zhang Lin
2005-01-01
Based on multi-module-cascaded inverter topology, this study presented a universal multilevel inverter hybrid topology and unified the researches on multilevel inverter topology. According to the freedom of this universal topology, several new hybrid topologies were constructed. Also, based on conventional modulation strategies- multi-carrier SPWM (Sinusoidal Pulse Width Modulation), hybrid modulation strategies were introduced corresponding to hybrid topologies, and a multilevel SVPWM (Space Vector Pulse Width Modulation) technique based on phase-shifted theory was naturally produced. Simulation and experiment results prove that hybrid topologies and corresponding modulation strategies are valid, which lay a foundation for practical application of hybrid multilevel inverter topologies.
A review of module inverter topologies suitable for photovoltaic system
DEFF Research Database (Denmark)
Variath, Reshmi C; Andersen, Michael A. E.; Nielsen, Ole Neis
2010-01-01
This paper evaluates eight module inverter topologies and provides an overview of the merits and demerits of each on the basis of circuit level Pspice simulation. The complete system is modeled in Pspice and the model is made as realistic as possible by including the parasitic elements. Only the ...
Optimization of SiC-based H5 and conergy-NPC transformerless PV inverters
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2015-01-01
of the output filter. In addition, the silicon carbide (SiC)-based power semiconductors are capable to operate reliably at high operating temperature and switching frequency levels combined with a very high efficiency. In this paper, a new design technique is presented for optimizing the switching frequency...... and structure of the output filter (either LCL- or LLCL-type) in transformerless H5 and conergy-neutral point clamped (Conergy-NPC) PV inverters, which employ SiC-type power devices. The design results demonstrate that the optimized SiC-based H5 and Conergy-NPC transformerless PV inverters are more effective...... in terms of energy production than their nonoptimized and silicon (Si)-based counterparts. In addition, by reducing the market price of SiC-type power semiconductors to the level of Si-based power devices, enables the development of optimized SiC-based PV inverters with a lower cost of energy than...
Directory of Open Access Journals (Sweden)
Faa Jeng Lin
2016-11-01
Full Text Available This paper outlines the modeling and controller design of a novel two-stage photovoltaic (PV micro inverter (MI that eliminates the need for an electrolytic capacitor (E-cap and input current sensor. The proposed MI uses an active-clamped current-fed push-pull DC-DC converter, cascaded with a full-bridge inverter. Three strategies are proposed to cope with the inherent limitations of a two-stage PV MI: (i high-speed DC bus voltage regulation using an integrator to deal with the 2nd harmonic voltage ripples found in single-phase systems; (ii inclusion of a small film capacitor in the DC bus to achieve ripple-free PV voltage; (iii improved incremental conductance (INC maximum power point tracking (MPPT without the need for current sensing by the PV module. Simulation and experimental results demonstrate the efficacy of the proposed system.
Leakage Current Elimination of Four-Leg Inverter for Transformerless Three-Phase PV Systems
DEFF Research Database (Denmark)
Guo, Xiaoqiang; He, Ran; Jian, Jiamin
2016-01-01
Eliminating the leakage current is one of the most important issues for transformerless three phase photovoltaic (PV) systems. In this paper, the leakage current elimination of a three-phase four-leg PV inverter is investigated. With the common mode loop model established, the generation mechanis...... the different modulation methods are implemented and tested on the TMS320F28335 DSP +XC3S400 FPGA digital control platform. The experimental results verify the effectiveness of the proposed solution....
Analysis of PV Advanced Inverter Functions and Setpoints under Time Series Simulation.
Energy Technology Data Exchange (ETDEWEB)
Seuss, John [Georgia Inst. of Technology, Atlanta, GA (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States)
2016-05-01
Utilities are increasingly concerned about the potential negative impacts distributed PV may have on the operational integrity of their distribution feeders. Some have proposed novel methods for controlling a PV system's grid - tie inverter to mitigate poten tial PV - induced problems. This report investigates the effectiveness of several of these PV advanced inverter controls on improving distribution feeder operational metrics. The controls are simulated on a large PV system interconnected at several locations within two realistic distribution feeder models. Due to the time - domain nature of the advanced inverter controls, quasi - static time series simulations are performed under one week of representative variable irradiance and load data for each feeder. A para metric study is performed on each control type to determine how well certain measurable network metrics improve as a function of the control parameters. This methodology is used to determine appropriate advanced inverter settings for each location on the f eeder and overall for any interconnection location on the feeder.
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...
Energy Technology Data Exchange (ETDEWEB)
NONE
2002-11-01
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into the specifications. Based on these two documents, a set of 23 topologies was analysed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies are in this report further investigated by means of an initial design-iteration and simulations. The items of interest in this report are efficiency and component ratings (magnetics, transistors, diodes and capacitors). The simulations reveal that DC-to-DC converters (for amplifying the PV-Module voltage) build on resonant technology (series-resonant and parallel-resonant) all suffers from high circulating currents inside the resonant tank; qua a low efficiency is the result. Whereas, the standard full-bridge converter and the novel MOHAN converter do not suffers from these severe currents, which also reflects into a higher efficiency. The ratings for the resonant converters are also somewhat larger than for the two other solutions. The two selected DC/DC converters are, on the basis of these properties, the standard full-bridge converter and the MOHAN converter. The simulated DC-to-AC inverters (for modulating the sinusoidal grid current) both show excellent performance in terms of high efficiency and low ratings. However, it seems that the MOSFET equipped inverters has lower losses than the IGBT equipped one. The last inverter investigated is the novel Dual FlyBack Inverter, which both amplifies the PV-Module voltage and modulates the sinusoidal grid current in one single process. Unfortunately, this circuit suffers from a low efficiency due to a high internal current. However, the efficiency is expected to increase with an increasing switching frequency, so the inverter is also selected for further design. A novel 'single-step' solution emerged at the end of the period: the
High Efficiency Single-stage Grid-tied PV Inverter for Renewable Energy System
2012-01-01
A single-phase grid connected transformerless photovoltaic (PV) inverter for residential application is presented. The inverter is derived from a boost cascaded with buck converter along with a line frequency unfolding circuit. Due to its novel operating modes, high efficiency can be achieved because there is only one switch operating at high frequency at a time, and the converter allows the use of power MOSFET and ultra-fast reverse recovery diode. This dissertation begins with theoretical a...
Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies
DEFF Research Database (Denmark)
Kerekes, Tamas; Liserre, Marco; Teodorescu, Remus
2009-01-01
This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study...... the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has...
A NEW MULTILEVEL INVERTER TOPOLOGY USING LESS NUMBER OF SWITCHES
Directory of Open Access Journals (Sweden)
MURUGESAN.G,
2011-02-01
Full Text Available The emergence of multilevel inverters has been in increase since the last decade. These new types of converters are suitable for high voltage and high power application due to their ability to synthesize waveforms with better harmonic spectrum. Numerous topologies have been introduced and widely studied for utility and drive applications. Amongst these topologies, the multilevel cascaded inverter was introduced in Static VAR compensation and drive systems. This project presents a new technique for getting a multilevel output and also uses PWM control techniques. In this technique, the number of switches used for the dc to ac conversion is reduced. So this dc to ac conversion significantly reduces the initial cost. This technique exhibits some attractive features which suits industrial applications. MATLAB simulink environment is used to simulate the results. The hardware results are also presented for the proposed technique.
Advanced Inverter Technology for High Penetration Levels of PV Generation in Distribution Systems
Energy Technology Data Exchange (ETDEWEB)
Schauder, C.
2014-03-01
This subcontract report was completed under the auspices of the NREL/SCE High-Penetration Photovoltaic (PV) Integration Project, which is co-funded by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) and the California Solar Initiative (CSI) Research, Development, Demonstration, and Deployment (RD&D) program funded by the California Public Utility Commission (CPUC) and managed by Itron. This project is focused on modeling, quantifying, and mitigating the impacts of large utility-scale PV systems (generally 1-5 MW in size) that are interconnected to the distribution system. This report discusses the concerns utilities have when interconnecting large PV systems that interconnect using PV inverters (a specific application of frequency converters). Additionally, a number of capabilities of PV inverters are described that could be implemented to mitigate the distribution system-level impacts of high-penetration PV integration. Finally, the main issues that need to be addressed to ease the interconnection of large PV systems to the distribution system are presented.
2013-01-01
In three-phase photovoltaic (PV) system, three-phase filter inductors are important part for the output electrical power quality. The comparison analyses of three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors in three-phase PV inverter are proposed. Firstly, the three-phase PV inverter operation with discrete filter inductors is analyzed, and the design of discrete filter inductors is given; then operation of the three-phase PV inverter with three-ph...
Directory of Open Access Journals (Sweden)
Ammar Hussein Mutlag
2014-01-01
Full Text Available This paper presents an adaptive fuzzy logic controller (FLC design technique for photovoltaic (PV inverters using differential search algorithm (DSA. This technique avoids the exhaustive traditional trial and error procedure in obtaining membership functions (MFs used in conventional FLCs. This technique is implemented during the inverter design phase by generating adaptive MFs based on the evaluation results of the objective function formulated by the DSA. In this work, the mean square error (MSE of the inverter output voltage is used as an objective function. The DSA optimizes the MFs such that the inverter provides the lowest MSE for output voltage and improves the performance of the PV inverter output in terms of amplitude and frequency. The design procedure and accuracy of the optimum FLC are illustrated and investigated using simulations conducted for a 3 kW three-phase inverter in a MATLAB/Simulink environment. Results show that the proposed controller can successfully obtain the desired output when different linear and nonlinear loads are connected to the system. Furthermore, the inverter has reasonably low steady state error and fast response to reference variation.
A Hybrid Power Control Concept for PV Inverters with Reduced Thermal Loading
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
on a single-phase PV inverter under yearly operation is presented with analyses of the thermal loading, lifetime, and annual energy yield. It has revealed the trade-off factors to select the power limit and also verified the feasibility and the effectiveness of the proposed control concept....
Frequency Adaptive Repetitive Control of Grid-Tied Single-Phase PV Inverters
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
. This paper thus explores a frequency adaptive repetitive control strategy for grid converters, which employs fractional delay filters in order to adapt to the change of the grid frequency. Case studies with experimental results of a single-phase grid-connected PV inverter system are provided to verify...
A New Method of On-line Grid Impedance Estimation for PV Inverter
DEFF Research Database (Denmark)
Teodorescu, Remus; Asiminoaei, Lucian; Blaabjerg, Frede
2004-01-01
for on-line measuring the grid impedance is presented. The presented method requires no extra hardware being accommodated by typical PV inverters, sensors and CPU, to provide a fast and low cost approach of on-line impedance measurement. By injecting a non-characteristic harmonic current and measuring...
DEFF Research Database (Denmark)
Wang, Huai; Yang, Yongheng; Blaabjerg, Frede
2013-01-01
The efficiency of 98% has been reported on transformer-less photovoltaic (PV) inverters and the penetration of grid-connected PV systems is booming as well. In the future, the PV systems are expected to contribute to the grid stability by means of low voltage ride-through operation and grid suppo...
An Enhanced Inverter Controller for PV Applications Using the dSPACE Platform
Directory of Open Access Journals (Sweden)
M. A. Hannan
2010-01-01
Full Text Available This paper presents the simulation modeling and prototype development of an inverter controller for photovoltaic (PV applications using the dSPACE DS1104 controller platform. The controller platform can link the simulation model developed in the MATLAB/SIMULINK environment to its prototype hardware. In the dSPACE controller, the voltage regulator controls the inverter by employing a proportional integral (PI controller and the Park transformation method to generate sinusoidal pulse-width modulation (SPWM signals. The SPWM signals switch the insulated gate bipolar transistor (IGBT to stabilize the 50-Hz sinusoidal AC output voltages of the inverter. The simulation was performed with a DC power supply that acts as the PV generator to supply the power to the inverter. The simulation model was then translated into the inverter prototype using the dSPACE platform and tested in the laboratory to prove the efficacy of the proposed controller. The experimental results for the inverter system demonstrated the feasibility of the proposed control strategy by maintaining the THD of the output voltage at 4.6%.
Basic study on dynamic reactive-power control method with PV output prediction for solar inverter
Directory of Open Access Journals (Sweden)
Ryunosuke Miyoshi
2016-01-01
Full Text Available To effectively utilize a photovoltaic (PV system, reactive-power control methods for solar inverters have been considered. Among the various methods, the constant-voltage control outputs less reactive power compared with the other methods. We have developed a constant-voltage control to reduce the reactive-power output. However, the developed constant-voltage control still outputs unnecessary reactive power because the control parameter is constant in every waveform of the PV output. To reduce the reactive-power output, we propose a dynamic reactive-power control method with a PV output prediction. In the proposed method, the control parameter is varied according to the properties of the predicted PV waveform. In this study, we performed numerical simulations using a distribution system model, and we confirmed that the proposed method reduces the reactive-power output within the voltage constraint.
DEFF Research Database (Denmark)
Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
The widespread adoption of mixed renewables urgently require reactive power exchange at various feed-in points of the utility grid. Photovoltaic (PV) inverters are able to provide reactive power in a decentralized manner at the grid-connection points even outside active power feed-in operation......, especially at night when there is no solar irradiance. This serves as a motivation for utilizing the PV inverters at night for reactive power compensation. Thus, an analysis on the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance and the reliability has...
Mission Profile Based Sizing of IGBT Chip Area for PV Inverter Applications
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Yang, Yongheng;
2016-01-01
Maximizing the total energy generation is of importance for Photovoltaic (PV) plants. This paper proposes a method to optimize the IGBT chip area for PV inverters to minimize the annual energy loss of the active switches based on long-term operation conditions (i.e., mission profile). The design...... process is firstly introduced. Then the power loss, thermal characteristic and lifetime for IGBT modules with different chip areas are modeled. After that, the dependence of the annual energy loss and maximum junction temperature on the IGBT chip area and switching frequency is derived under a specific...
Online Grid Measurement and ENS Detection for PV Inverter Running on Highly Inductive Grid
DEFF Research Database (Denmark)
Timbus, Adrian Vasile; Teodorescu, Remus; Blaabjerg, Frede;
2004-01-01
Photovoltaic (PV) and other sources of renewable energy are being used increasingly in grid-connected systems, for which stronger power quality requirements are being issued. Continuous grid monitoring should be considered so as to provide safe connections and disconnections from the grid....... This letter gives an overview of the methods used for online grid measurement with PV inverters. Emphasis is placed on a method based on the injection of a noncharacteristic harmonic in the grid. Since this injection is regarded as a disturbance for the grid, different issues, i.e., the influence on total...
S4 Grid-Connected Single-Phase Transformerless Inverter for PV Application
DEFF Research Database (Denmark)
Ardashir, Jaber Fallah; Siwakoti, Yam Prasad; Sabahi, Mehran;
2016-01-01
This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative termin...... clearly verify the performance of the proposed inverter and its practical application for grid-connected PV systems.......This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative terminal...... of the PV source. This results in a constant common-mode voltage and almost zero leakage current. A unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to modulate the inverter to reduce the output current ripple and the filter requirements. The main advantages of this inverter are compact...
Energy Technology Data Exchange (ETDEWEB)
Nelson, Austin; Martin, Gregory; Hurtt, James
2017-05-08
As revised interconnection standards for grid-tied photovoltaic (PV) inverters address new advanced grid support functions (GSFs), there is increasing interest in inverter performance in the case of abnormal grid conditions. The growth of GSF-enabled inverters has outpaced the industry standards that define their operation, although recently published updates to UL1741 with Supplement SA define test conditions for GSFs such as volt-var control, frequency-watt control, and volt-age/frequency ride-through, among others. A comparative experimental evaluation has been completed on four commercially available, three-phase PV inverters in the 24.0-39.8 kVA power range on their GSF capability and the effect on abnormal grid condition response. This study examines the impact particular GSF implementations have on run-on times during islanding conditions, peak voltages in load rejection overvoltage scenarios, and peak currents during single-phase and three-phase fault events for individual inverters. This report reviews comparative test data, which shows that GSFs have little impact on the metrics of interest in most tests cases.
Real field mission profile oriented design of a SiC-based PV-inverter application
DEFF Research Database (Denmark)
Sintamarean, Nicolae Christian; Blaabjerg, Frede; Wang, Huai;
2013-01-01
This paper introduces a real field mission profile oriented design tool for the new generation of grid connected PV-inverters applications based on SiC-devices. The proposed design tool consists of a grid connected PV-inverter model, an ElectroThermal model, a converter safe operating area (SOA...... Zth_H in order to perform in a safe mode for the whole operating range. Furthermore, the proposed design tool considers the mission profile (the measured solar irradiance and ambient temperature) from the real field where the converter will operate. Thus, a realistic loading of the converter devices...... is achieved. To consider one year real field measurements of the mission profile, an accurate long term simulation model is developed. The model predicts the junction and case temperature of the converter devices, for three different case scenarios. In the first case, a one year mission profile is used...
Energy Technology Data Exchange (ETDEWEB)
Ding, Fei; Pratt, Annabelle; Bialek, Tom; Bell, Frances; McCarty, Michael; Atef, Kahveh; Nagarajan, Adarsh; Gotseff, Peter
2016-11-21
This paper reports on tools and methodologies developed to study the impact of adding rooftop photovoltaic (PV) systems, with and without the ability to provide voltage support, on the voltage profile of distribution feeders. Simulation results are provided from a study of a specific utility feeder. The simulation model of the utility distribution feeder was built in OpenDSS and verified by comparing the simulated voltages to field measurements. First, we set all PV systems to operate at unity power factor and analyzed the impact on feeder voltages. Then we conducted multiple simulations with voltage support activated for all the smart PV inverters. These included different constant power factor settings and volt/VAR controls.
Energy Technology Data Exchange (ETDEWEB)
Mather, B.
2014-08-01
The National Renewable Energy Laboratory/Southern California Edison High-Penetration PV Integration Project is (1) researching the distribution system level impacts of high-penetration photovoltaic (PV) integration, (2) determining mitigation methods to reduce or eliminate those impacts, and (3) seeking to demonstrate these mitigation methods on actual high-penetration PV distribution circuits. This report describes a field demonstration completed during the fall of 2013 on the Fontana, California, study circuit, which includes a total of 4.5 MW of interconnected utility-scale rooftop PV systems. The demonstration included operating a 2-MW PV system at an off-unity power factor that had been determined during previously completed distribution system modeling and PV impact assessment analyses. Data on the distribution circuit and PV system operations were collected during the 2-week demonstration period. This demonstration reinforces the findings of previous laboratory testing that showed that utility-scale PV inverters are capable of operating at off-unity power factor to mitigate PV impacts; however, because of difficulties setting and retaining PV inverter power factor set points during the field demonstration, it was not possible to demonstrate the effectiveness of off-unity power factor operation to mitigate the voltage impacts of high-penetration PV integration. Lessons learned from this field demonstration are presented to inform future field demonstration efforts.
DEFF Research Database (Denmark)
Sintamarean, Nicolae Cristian; Wang, Huai; Blaabjerg, Frede
2014-01-01
This paper introduces a reliability-oriented design tool for a new generation of grid connected PV-inverters. The proposed design tool consists of a real field mission profile model (for one year operation in USA-Arizona), a PV-panel model, a grid connected PV-inverter model, an electro-thermal m...
Directory of Open Access Journals (Sweden)
Ying Jiang
2013-01-01
Full Text Available In three-phase photovoltaic (PV system, three-phase filter inductors are important part for the output electrical power quality. The comparison analyses of three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors in three-phase PV inverter are proposed. Firstly, the three-phase PV inverter operation with discrete filter inductors is analyzed, and the design of discrete filter inductors is given; then operation of the three-phase PV inverter with three-phase integrated five-limb magnetic core filter inductors is analyzed, the design of integrated filter inductors with five-limb magnetic core is given, then the operation of three-phase PV inverter with three-phase integrated three-limb magnetic core filter inductors is analyzed, and the design of integrated filter inductors with three limbs magnetic core is given. The conclusion of comparison between three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors is done; it means that the three-phase discrete filter inductors can achieve better output electrical power quality with lower power density and three-phase integrated filter inductors can achieve higher power density with lower output electrical power quality. Finally, the experiment results are given to compare the volume and filter effect of three kinds of filter inductors in three-phase PV inverter.
Stability of Grid-Connected PV Inverters with Large Grid Impedance Variation
DEFF Research Database (Denmark)
Liserre, Marco; Teodorescu, Remus; Blaabjerg, Frede
2004-01-01
Photovoltaic (PV) inverters used in dispersed power generation of houses in the range of 1-5 kW are currently available from several manufactures. However, large grid impedance variation is challenging the control and the grid filter design in terms of stability. In fact the PV systems are well...... suited for loads connected in a great distance to the transformer (long wires) and the situation becomes even more difficult in low-developed remote areas characterized by low power transformers and long distribution wires with high grid impedance. Hence a theoretical analysis is needed because the grid...... the design of resonant controllers adopted to mitigate the effect of the grid harmonic distortion on the grid current. In the high frequency range the grid impedance influence the frequency characteristic of the filter and the design of passive or active damping (to ensure stability) becomes more difficult...
Directory of Open Access Journals (Sweden)
Rajnish Kumar Sharma
2016-08-01
Full Text Available In this research, a single phase Z-source cascading Multilevel Inverter, Nine-level inverter topologies with a trinary DC sources are offered. The recommended topologies are expanded by cascading a full bridge inverter with dissimilar DC sources. This paper recommends advanced pulse with modulation technique as a switching scheme. In this PWM technology, trapezoidal modulation technique is used as variable amplitude pulse width modulation. These topologies compromise reduced harmonics present in the output voltage and superior root mean square (RMS values of the output voltages linked with the traditional trapezoidal pulse width modulation. The simulation of proposed circuit is carried out by using MATLAB/SIMULINK.
DEFF Research Database (Denmark)
Wang, Huai; Yang, Yongheng; Blaabjerg, Frede
2013-01-01
The efficiency of 98% has been reported on transformer-less photovoltaic (PV) inverters and the penetration of grid-connected PV systems is booming as well. In the future, the PV systems are expected to contribute to the grid stability by means of low voltage ride-through operation and grid support....... At the same time, the target of a long service time (25 years or more) imposes new challenges to grid-connected transformer-less PV systems. Achieving more reliable PV inverters is of intense interest in recent research. As one of the most critical stresses that induce failures, the thermal stresses...... on the power devices of a single-phase full-bridge PV inverter are analyzed in different operational modes in this paper. The low voltage grid condition is specially taken into account in this paper. The analysis is demonstrated by a 3 kW single-phase full-bridge grid-connected PV system by simulations...
Energy Technology Data Exchange (ETDEWEB)
Nelson, Austin; Prabakar, Kumaraguru; Nagarajan, Adarsh; Nepal, Shaili; Hoke, Anderson; Asano, Marc; Ueda, Reid; Ifuku, Earle
2017-05-08
As more grid-connected photovoltaic (PV) inverters become compliant with evolving interconnections requirements, there is increased interest from utilities in understanding how to best deploy advanced grid-support functions (GSF) in the field. One efficient and cost-effective method to examine such deployment options is to leverage power hardware-in-the-loop (PHIL) testing methods. Two Hawaiian Electric feeder models were converted to real-time models in the OPAL-RT real-time digital testing platform, and integrated with models of GSF capable PV inverters that were modeled from characterization test data. The integrated model was subsequently used in PHIL testing to evaluate the effects of different fixed power factor and volt-watt control settings on voltage regulation of the selected feeders. The results of this study were provided as inputs for field deployment and technical interconnection requirements for grid-connected PV inverters on the Hawaiian Islands.
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng; Loh, Poh Chiang
2011-01-01
Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system......, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DC converters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second......-order harmonic current caused by single-phase inverter. In the proposed compact topology, a small size DC-link capacitor can achieve the same function through charging/discharging control of ultra-capacitor to mitigate second-order ripple current. Simulation results are provided to validate the effectiveness...
RTDS implementation of an improved sliding mode based inverter controller for PV system.
Islam, Gazi; Muyeen, S M; Al-Durra, Ahmed; Hasanien, Hany M
2016-05-01
This paper proposes a novel approach for testing dynamics and control aspects of a large scale photovoltaic (PV) system in real time along with resolving design hindrances of controller parameters using Real Time Digital Simulator (RTDS). In general, the harmonic profile of a fast controller has wide distribution due to the large bandwidth of the controller. The major contribution of this paper is that the proposed control strategy gives an improved voltage harmonic profile and distribute it more around the switching frequency along with fast transient response; filter design, thus, becomes easier. The implementation of a control strategy with high bandwidth in small time steps of Real Time Digital Simulator (RTDS) is not straight forward. This paper shows a good methodology for the practitioners to implement such control scheme in RTDS. As a part of the industrial process, the controller parameters are optimized using particle swarm optimization (PSO) technique to improve the low voltage ride through (LVRT) performance under network disturbance. The response surface methodology (RSM) is well adapted to build analytical models for recovery time (Rt), maximum percentage overshoot (MPOS), settling time (Ts), and steady state error (Ess) of the voltage profile immediate after inverter under disturbance. A systematic approach of controller parameter optimization is detailed. The transient performance of the PSO based optimization method applied to the proposed sliding mode controlled PV inverter is compared with the results from genetic algorithm (GA) based optimization technique. The reported real time implementation challenges and controller optimization procedure are applicable to other control applications in the field of renewable and distributed generation systems.
Directory of Open Access Journals (Sweden)
Tofael Ahmed
2014-06-01
Full Text Available In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT is proposed for photovoltaic (PV systems. This proposed system utilizes a single-ended primary inductor (SEPIC converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximum power point (MPP and the semi-Z-source inverter utilizes a nonlinear SPWM to produce sinusoidal voltage at the output. The proposed system is able to track the MPP of PV arrays and produce an AC voltage at its output by utilizing only three switches. Experimental results show that the fast-converging MPPT algorithm has fast tracking response with appreciable MPP efficiency. In addition, the inverter shows the minimization of common mode leakage current with its ground sharing feature and reduction of the THD as well as DC current components at the output during DC-AC conversion.
DEFF Research Database (Denmark)
Ardashir, Jaber Fallah; Sabahi, Mehran; Hosseini, Seyed Hossein
2017-01-01
resonant control strategy is used to control the injected current. The main benefits of the proposed inverter are: the neutral of the grid is directly connected to the negative terminal of the PV panel, so the leakage current is eliminated; its compact size; low cost; the used dc voltage of the proposed...
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Agelidis, Vassilios; Teodorescu, Remus
2008-01-01
Islanding prediction is a necessary feature of inverter-based photovoltaic (PV) system in order to meet stringent standard requirements for interconnection with the electrical grid. Both passive and active anti-islanding methods exist. Typically, active methods modify a given parameter, which also...
Energy Technology Data Exchange (ETDEWEB)
Baekhoej Kjaer, S.
2002-06-01
The PHOTONERGY{sup TM} project (also known as the former 'SolcelleInverter' project) is by this report carried into its third stage; the selection of a suitable topology for the AC-Module inverter. The selection of a suitable topology is based on State-Of-The-Art analysis a specifications and a comparison of four grid-tied inverters and nine dc/dc converters. This implies 23 possible combinations, from which nine is investigated with respect to efficiency in six working points, the number of components and to some extent also the rating of the components. The conclusion is that the target of a European efficiency of 93.7% is hard to achieve. But four of the examined, and two newly discovered, inverters are recommended for a further examination by means of estimations, calculations and simulations of: cost, complexity, robustness, efficiency and mass-production. The system-layout is also examined. The first layout implies that the PV-Module and the inverter is integrated into one unit and the second layout involves that the inverter is placed indoor. The layouts are compared with respect to cable-losses, enclosure demanding and lifetime. The conclusion is somehow ambiguous and a further investigation should be initiated in order to get a clear result. (au)
Directory of Open Access Journals (Sweden)
MASUDUL HAIDER IMTIAZ
2010-12-01
Full Text Available This paper demonstrates the implementation of a prototype of IPS (instant power supply system to ensure continuous output current to load in residential application utilizing both Photovoltaic (PV energy and AC Grid. Utility interfacing PWM inverter designed here to operate by both solar energy and storage batteries that highly satisfies the necessity in rural areas where National Grids are hardly available and power cut problem reduces the effectiveness of IPS. Solar energy gets priority here to charge storage battery rather than AC source that may save hundreds of mega watts power every day. To extend the battery lifetime and keep system components hazard-free, it includes exact battery-level sensing, charging- urrent controlling by microcontroller unit (MCU and a cumulative DC/AC MPPT (Maximum Power Point Tracking charging to congregatemaximum PV energy from AC Solar Modules. Investigation on improvement of power-interfacing control and optimization of overall system operation assent to intend usage recommendation in this exposition. Computer simulations and experiment results show the validity of this proposed system to have high power conversion efficiency and low harmonic distortions.
Three-Phase PV CHB Inverter for a Distributed Power Generation System
Directory of Open Access Journals (Sweden)
Pierluigi Guerriero
2016-10-01
Full Text Available This work deals with the design of a three-phase grid-tied photovoltaic (PV cascade H-bridge inverter for distributed power conversion. The power balancing among the phases must be properly addressed. In fact, an intra-phase power imbalance—arising from uneven irradiance and temperature conditions—generates a per-phase power imbalance. This latter can be compensated by the injection of a proper zero-sequence voltage, while the intra-phase balance is ensured by means of a hybrid modulation method which is able to guarantee the handling of unequal DC (Direct Current sources, stable circuit operation, and maximization of PV power production. The digital controller is developed and tested in Matlab/Simulink environment integrated with XSG (Xilinx System Generator, thus allowing an easy transfer on a field-programmable gate array (FPGA platform and accurately describing the behavior of a real hardware implementation. Thus, numerical results have been considered to prove the effectiveness of the proposed approach.
The Impact of Gate-Driver Parameters Variation and Device Degradation in the PV-Inverter Lifetime
DEFF Research Database (Denmark)
Sintamarean, Nicolae Cristian; Wang, Huai; Blaabjerg, Frede;
2014-01-01
This paper introduces a reliability-oriented design tool for a new generation of grid connected PV-inverters. The proposed design tool consists of a real field Mission Profile (MP) model (for one year operation in USA-Arizona), a PV-panel model, a grid connected PV-inverter model, an Electro......-Thermal model and the lifetime model of the power semiconductor devices. A simulation model able to consider a one year real field operation conditions (solar irradiance and ambient temperature) is developed. Thus, one year estimation of the converter devices thermal loading distribution is achieved...... and is further used as an input to a lifetime model. The proposed reliability oriented design tool is used to study the impact of MP-variation, Gate-Driver (GD) parameters variation and device degradation in the PVinverter lifetime. The obtained results indicate that in order to improve the accuracy...
The Impact of Gate-Driver Parameters Variation and Device Degradation in the PV-Inverter Lifetime
DEFF Research Database (Denmark)
Sintamarean, Nicolae Cristian; Wang, Huai; Blaabjerg, Frede
2014-01-01
This paper introduces a reliability-oriented design tool for a new generation of grid connected PV-inverters. The proposed design tool consists of a real field Mission Profile (MP) model (for one year operation in USA-Arizona), a PV-panel model, a grid connected PV-inverter model, an Electro......-Thermal model and the lifetime model of the power semiconductor devices. A simulation model able to consider a one year real field operation conditions (solar irradiance and ambient temperature) is developed. Thus, one year estimation of the converter devices thermal loading distribution is achieved...... and is further used as an input to a lifetime model. The proposed reliability oriented design tool is used to study the impact of MP-variation, Gate-Driver (GD) parameters variation and device degradation in the PVinverter lifetime. The obtained results indicate that in order to improve the accuracy...
Power Inverter Topologies for Photovoltaic Modules - A Review
DEFF Research Database (Denmark)
Kjær, Søren Bækhøj; Pedersen, John Kim; Blaabjerg, Frede
2002-01-01
This review-paper focuses on the latest development of inverters for photovoltaic AC-Modules. The power range for these inverters is usually within 90 Watt to 500 Watt, which covers the most commercial photovoltaic-modules. Self-commutated inverters have replaced the grid-commutated ones. The same...... is true for the bulky low-frequency transformers versus the high-frequency transformers, which are used to adapt the voltage level. The AC-Module provides a modular design and a flexible behaviour in various grid conditions. It hereby opens the market for photovoltaic-power for everyone at a low cost due...
Extended topologies of tapped-inductor Z-source inverters
DEFF Research Database (Denmark)
Zhu, Miao; Li, Ding; Gao, Feng;
2011-01-01
has already been discussed throughout the paper, before experimental results are presented for verifying them. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested....... into a generic network entity, which is termed hybrid-source tapped-inductor impedance network. The resulting novel Z-source inverters would have a higher output voltage gain and other unique advantages that currently have not yet been investigated. Theoretical analysis for explaining these operating features...
Shunt Active-Power-Filter Topology Based on Parallel Interleaved Inverters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Asiminoaei, Lucian; Aeloiza, E.
2008-01-01
In this paper, an interleaved active-power-filter concept with reduced size of passive components is discussed. The topology is composed of two pulsewidth-modulation interleaved voltage-source inverters connected together on the ac line and sharing the same dc-link capacitor. The advantages......, because the power sharing allows one to use a higher switching frequency in each inverter. This paper analyzes the design of the passive components and gives a practical and low-cost solution for the minimization of the circulation currents between the inverters, by using common-mode coils. Several...
A new inverter topology using GTO commutation. [Gate Turn Off thyristor
Rippel, W. E.
1983-01-01
A new N-phase, forced commutated bridge inverter topology has been developed wherein a single Gate Turn Off Thyristor (GTO) is used to commutate each of 2N main Thyristors (SCRs). Since, for most applications, the primary loss mechanism is the SCR forward drop, very high efficiencies are possible. Compared with conventional pure SCR and pure GTO inverters, cost per kW is lower - in the former case due to the large cost differential between GTOs and SCRs. Other advantages of the new inverter include high power density, low switching losses and stresses, modulation flexibility and amenability to high voltage and high frequency operation.
A Systematic Method to Synthesize New Transformerless Full-bridge Grid-tied Inverters
DEFF Research Database (Denmark)
Wang, Hongliang; Burton, Sarah; Liu, Yan-Fei
2014-01-01
Many inverter topologies have been proposed to eliminate the leakage current of transformerless Full Bridge Grid-Tied photovoltaic (PV) inverters. These include implementations such as the H5, H6, and HERIC topologies, among others. In this paper, a new full bridge topology synthesis method, call...
Control of a Multi-Functional Inverter for Grid Integration of PV and Battery Energy Storage System
DEFF Research Database (Denmark)
Mousazadeh, Seyyed Yousef; Firoozabadi, Mehdi Savaghebi; Beirami, A.
2015-01-01
This paper presents a multi-functional control of a DC/AC inverter for Power Quality compensation of nonlinear and unequal local loads and grid integration of hybrid photovoltaic (PV) and battery energy storage systems. Multi-layer neural network estimator and a DC/DC converter are used for maximum...... and nonlinear local loads. The simulation results which implemented in MATLAB/SIMULINK software verify the effectiveness of the system....
Energy Technology Data Exchange (ETDEWEB)
West, R.
2012-12-01
Final report for Renewable Power Conversion. The overall objective of this project was to develop a prototype PV inverter which enables a new utility-scale PV system approach where the cost, performance, reliability and safety benefits of this new approach have the potential to make all others obsolete.
Directory of Open Access Journals (Sweden)
Bhattacharya Ananyo
2016-12-01
Full Text Available A novel circuit topology of modified switched boost high frequency hybrid resonant inverter fitted induction heating equipment is presented in this paper for efficient induction heating. Recently, induction heating technique is becoming very popular for both domestic and industrial purposes because of its high energy efficiency and controllability. Generally in induction heating, a high frequency alternating magnetic field is required to induce the eddy currents in the work piece. High frequency resonant inverters are incorporated in induction heating equipment which produce a high frequency alternating magnetic field surrounding the coil. Previously this high frequency alternating magnetic field was produced by voltage source inverters. But VSIs have several demerits. So, in this paper, a new scheme of modified switched boost high frequency hybrid resonant inverter fitted induction heating equipment has been depicted which enhances the energy efficiency and controllability and the same is validated by PSIM.
Delta Power Control Strategy for Multi-String Grid-Connected PV Inverters
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
With a still increasing penetration level of grid-connected PV systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required...... for the entire PV system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the delta power control strategy, where the power reserve according to the delta power constraint is achieved under several...
Development and implementation of a PV performance monitoring system based on inverter measurements
DEFF Research Database (Denmark)
Spataru, Sergiu; Gavriluta, Anamaria Florina; Sera, Dezso
2016-01-01
applications the cost of the performance monitoring hardware and implementation is still high. Therefore, we present the practical development and implementation of a low-cost PV performance monitoring system for residential and commercial PV applications, based on the inverter’s own monitoring......Performance monitoring and fault detection systems are becoming more common in large photovoltaic (PV) plants as they can contribute to decreasing operation and maintenance costs, as well as for maximizing plant yield and lifetime. However, in case of residential and smaller commercial PV system...
Delta Power Control Strategy for Multi-String Grid-Connected PV Inverters
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2017-01-01
With a still increasing penetration level of grid-connected PV systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required....... Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the proposed delta power control strategy, where the power reserve according to the delta power constraint is achieved under several operating conditions....
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.
Development and implementation of a PV performance monitoring system based on inverter measurements
DEFF Research Database (Denmark)
Spataru, Sergiu; Gavriluta, Anamaria Florina; Maaløe, Lars
2016-01-01
currently the cost of the performance monitoring hardware and implementation is high. Therefore, we present the practical development and implementation of a PV performance monitoring system for residential and commercial PV applications, where the cost of the monitoring hardware is lowered, by using......Performance monitoring and fault detection systems have become necessary for decreasing operation and maintenance cost in large photovoltaic (PV) plants, as well for maximizing plan yield and lifetime. We expect a similar development for residential and commercial PV system applications, where...... the inverter’s own monitoring and communication capabilities. We also aim to lower the implementation cost, by using a simple, but accurate performance monitoring approach, and show the practical issues that can arise when implementing such a system....
Anishkumar, A. R.; Sreejaya, P.
2016-12-01
Kerala is a state in India having a very good potential for solar PV energy production. The domestic customers in Kerala using PV system are approximately 15 % and almost all of them are using the off-grid PV system. When these off grid customers move to on-grid system, off grid system accessories such as inverter and batteries become redundant. In this paper, a switching logic has been developed for the effective utilization of off grid accessories and reducing islanding power loss for on grid customers. An algorithm is proposed for the switching logic and it is verified using simulation results and hardware implementation.
Neutral Point Clamped Non-isolated Full Bridge PV Grid-connected Inverters%中点钳位非隔离全桥光伏并网逆变器
Institute of Scientific and Technical Information of China (English)
张犁; 孙凯; 冯兰兰; 吴红飞; 徐明; 邢岩
2012-01-01
Two types of basic switching cells,positive-neutral point clamped cell and negative-neutral point clamped cell,and a method to build neutral point clamped（NPC） full bridge photovoltaic（PV） grid-connected inverters with these two basic cells are proposed to meet the demand for non-isolated inverter topology applied in PV generation system.A family of novel NPC non-isolated full bridge PV grid-connected inverters,besides existing topologies such as oH5 and FB-DCBP,is derived.Operation modes of the PN-NPC topology are analyzed as an example in detail.Finally,both of the efficiency and common-mode performance of the proposed PN-NPC and Heric topologies were compared with experimental results.And the comparison results show that the proposed PN-NPC topology features better efficiency and common-mode performance than that of the Heric topology.%针对光伏发电系统对非隔离逆变电路的需求,提出构成一类中点钳位非隔离全桥光伏并网逆变器的2种基本开关单元：中点钳位正单元（positive-neutral point clamped cell,P-NPCC）和中点钳位负单元（negative-neutral point clampedc ell,N-NPCC）。提出由2种基本单元构造中点钳位全桥逆变器拓扑的生成机理和推演方法,按照该方法可以得到现有的中点钳位非隔离全桥光伏并网逆变器拓扑,如oH5、FB-DCBP以及一族新的中点钳位非隔离全桥并网逆变器拓扑。以所提PN-NPC拓扑为例详细分析了其工作原理,并实验比较了PN-NPC和Heric拓扑的变换效率和共模特性。所提拓扑的共模电压为恒定值,且其变换效率和共模特性均优于Heric拓扑。
带续流开关的中点箝位型非隔离光伏逆变器%A neutral point clamped non-isolated PV inverter with a freewheeling switch
Institute of Scientific and Technical Information of China (English)
叶海云; 马海啸
2016-01-01
为了满足非隔离光伏发电系统低漏电流的要求，提出了一种带续流开关的中点箝位型非隔离光伏逆变器。该拓扑在全桥逆变器的交流侧加入了一个续流开关，使得太阳能电池板输出端与电网断开，提高了非隔离光伏逆变器的转换效率。另一方面中点箝位电路的应用使得该拓扑在功率处理阶段和续流阶段的共模电压基本保持不变，降低了漏电流。详细分析了拓扑的工作原理，给出了其控制方法，并通过Saber仿真软件验证了带续流开关的中点箝位型非隔离光伏逆变器良好的共模特性。实验研制了一台300 W的原理样机验证了理论分析的正确性及仿真方案的可行性。%In order to meet the requirement of common-mode leakage current in photovoltaic ( PV) generation sys-tems, a neutral point clamped non-isolated PV inverter with a freewheeling switch is proposed .A freewheeling switch is added in AC side of the full bridge inverter in this topology , which will improve the non-isolated PV inverter conver-sion efficiency because the freewheeling switch makes the output of the solar panels off the grid .On the other hand , common-mode voltage remains constant on power processing and freewheeling stage owing to the neutral point clamped circuit.The operational principle of topology is analyzed in detail and its controlling strategy is introduced in this pa -per.It is proved that common-mode performance of the proposed topology was good by Saber simulation software .The effectiveness and feasibility of the proposed topology and strategy have been verified in a prototype rated at 300 W.
Reliability-Driven Assessment of GaN HEMTs and Si IGBTs in 3L-ANPC PV Inverters
DEFF Research Database (Denmark)
Gurpinar, Emre; Yang, Yongheng; Iannuzzo, Francesco;
2016-01-01
possibilities: 1) with TIM at 10 kHz, 2) without TIM at 10 kHz, and 3) with TIM at 300 kHz has been performed. The assessment results indicate lower thermal stress with GaN HEMT devices at 10 kHz in comparison to Si IGBT. At high switching frequencies, the results show significant system level cost savings can......In this paper, thermal loading of the state-of-the-art GaN HEMTs and traditional Si IGBTs in 3L-ANPC PV inverters is presented considering real-field long-term mission profiles (i.e., ambient temperature and solar irradiance). A comparison of Si IGBT against GaN HEMT with three different...
Directory of Open Access Journals (Sweden)
Emerson Charles M. Silva
2013-09-01
Full Text Available This paper presents a proposal for a voltage inverter topology based on push-pull converters, switched at high frequency to inject energy into the grid from a source of DC power. A system using two reverse voltage static converters provides the power grid; energy in the form of alternating current, that can work in conjunction with the provision of utility power. Aiming at the possible use of renewable energy sources, that can be stored in the form of voltage continuous, such as wind, solar, hydroelectric and others. The functioning of topology is presented, such as the power and control circuits, as well as sizing components, theoretical and practical results achieved with the assembly of a prototype 100W of power and switching in 40khz, which after filtering provides the frequency of 60Hz, which is compatible with the Brazilian electrical system.
S4 Grid-Connected Single-Phase Transformerless Inverter for PV Application
DEFF Research Database (Denmark)
Ardashir, Jaber Fallah; Siwakoti, Yam Prasad; Sabahi, Mehran
2016-01-01
This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative termin...
Lyapunov-Based Control Scheme for Single-Phase Grid-Connected PV Central Inverters
Meza, C.; Biel, D.; Jeltsema, D.; Scherpen, J. M. A.
2012-01-01
A Lyapunov-based control scheme for single-phase single-stage grid-connected photovoltaic central inverters is presented. Besides rendering the closed-loop system globally stable, the designed controller is able to deal with the system uncertainty that depends on the solar irradiance. A laboratory p
Lyapunov-Based Control Scheme for Single-Phase Grid-Connected PV Central Inverters
Meza, C.; Biel, D.; Jeltsema, D.; Scherpen, J. M. A.
2012-01-01
A Lyapunov-based control scheme for single-phase single-stage grid-connected photovoltaic central inverters is presented. Besides rendering the closed-loop system globally stable, the designed controller is able to deal with the system uncertainty that depends on the solar irradiance. A laboratory p
Institute of Scientific and Technical Information of China (English)
张犁; 孙凯; 冯兰兰; 邢岩; 徐明
2012-01-01
为满足非隔离光伏并网发电系统对共模漏电流的限制，提出一种六开关逆变器拓朴（H6拓扑）。所提出的H6拓扑在功率传输模态时，进网电流半个工频周期流过3支开关管，而另半个工频周期流过2支开关管，故相对于H5拓扑，降低了通态损耗，有利于热应力均衡，且仍满足续流阶段光伏电池输出端与电网脱离的要求。详细分析拓扑的工作原理，并推论给出H6非隔离光伏并网逆变器的其它3种拓扑结构；比较分析了H5拓扑、Heric拓扑和H6拓扑的损耗和成本。通过1kW通用样机平台对比验证了上述3种拓扑的效率和共模特性。实验结果表明，H6拓扑的变换效率高于H5拓扑、但略低于Heric拓扑，共模特性优于Heric拓扑、但略劣于H5拓扑。%In order to meet the limit for common-mode leakage currents in grid-connected photovoltaic （PV） generation systems, a H6 non-isolated full bridge PV grid -connected inverter is proposed. In the power processing period, the grid-tied current flows through three power switches during one of half line cycles, while flows through only two power switches during another half line cycle. As a result, the conduction losses are reduced and the heat-stress balance is benefited with the proposed H6 topology, comparing with the H5 topology. The operation mode of the proposed topology is analyzed in detail and another three topologies of the H6 non-isolated full bridge grid-connected inverters has been derived. The power losses and costs are fairly compared among the H5 topology, Heric topology and the H6 topology. Finally, both of the conversion efficiency and common- mode performance of these topologies are compared with a universal prototype inverter rated at 1 kW. The experimental results show that the efficiency of the proposed H6 topology is higher than that of the H5 topology, while slightly being lower than that of the Heric topology. And the common
Energy Technology Data Exchange (ETDEWEB)
Palmintier, Bryan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Giraldez, Julieta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gruchalla, Kenny [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gotseff, Peter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nagarajan, Adarsh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Harris, Tom [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bugbee, Bruce [National Renewable Energy Lab. (NREL), Golden, CO (United States); Baggu, Murali [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gantz, Jesse [GE Grid Solutions, Fairfield, CT (United States); Boardman, Ethan [GE Grid Solutions, Fairfield, CT (United States)
2016-11-01
Duke Energy, Alstom Grid, and the National Renewable Energy Laboratory teamed up to better understand the impacts of solar photovoltaics (PV) on distribution system operations. The core goal of the project is to compare the operational - specifically, voltage regulation - impacts of three classes of PV inverter operations: 1.) Active power only (Baseline); 2.) Local inverter control (e.g., PF...not equal...1, Q(V), etc.); and 3.) Integrated volt-VAR control (centralized through the distribution management system). These comparisons were made using multiple approaches, each of which represents an important research-and-development effort on its own: a) Quasi-steady-state time-series modeling for approximately 1 year of operations using the Alstom eTerra (DOTS) system as a simulation engine, augmented by Python scripting for scenario and time-series control and using external models for an advanced inverter; b) Power-hardware-in-the-loop (PHIL) testing of a 500-kVA-class advanced inverter and traditional voltage regulating equipment. This PHIL testing used cosimulation to link full-scale feeder simulation using DOTS in real time to hardware testing; c) Advanced visualization to provide improved insights into time-series results and other PV operational impacts; and d) Cost-benefit analysis to compare the financial and business-model impacts of each integration approach.
Finishing report for the 'SolcelleInverter' project
Energy Technology Data Exchange (ETDEWEB)
Boekhoej Kjaer, S.
2005-03-01
The main objective for this research project was to develop an inverter for the AC module, where one PV module is equipped with its own dedicated inverter, and connected to the grid. A topology, among many different candidates, has been selected, based on analysis's. The inverter has been optimized in respect to cost, reliability, and efficiency, and a prototype has been build. (au)
Singh, S N
2010-01-01
With the increasing concern about global environmental protection and energy demand due to rapid growth of population in developing countries and the diminishing trend of resources of conventional grid supply, the need to produce freely available pollution free natural energy such as solar/wind energy has been drawing increasing interest in every corner of the world. In an effort to utilize these energies effectively through Power converter, a great deal of research is being carried out by different researchers / scientist and engineers at different places in the world to meet the increasing demand of load. The study presents methodology to integrate solar (PV) energy (which is freely available in every corner of the world) with grid source and supplement the existing grid power in rural houses during its cut off or restricted supply period. In order to get consistency in supply a DG is also added as a standby source in the proposed integration of network. The software using novel Direct PWM modulation strate...
Directory of Open Access Journals (Sweden)
Hamid Reza Mohammadi
2015-03-01
Full Text Available In this paper, a new control method for quasi-Z-source cascaded multilevel inverter based grid-connected photovoltaic (PV system is proposed. The proposed method is capable of boosting the PV array voltage to a higher level and solves the imbalance problem of DC-link voltage in traditional cascaded H-bridge inverters. The proposed control system adjusts the grid injected current in phase with the grid voltage and achieves independent maximum power point tracking (MPPT for the separate PV arrays. To achieve these goals, the proportional-integral (PI controllers are employed for each module. For achieving the best performance, this paper presents an optimum approach to design the controller parameters using particle swarm optimization (PSO. The primary design goal is to obtain good response by minimizing the integral absolute error. Also, the transient response is guaranteed by minimizing the overshoot, settling time and rise time of the system response. The effectiveness of the new proposed control method has been verified through simulation studies based on a seven level quasi-Z-Source cascaded multilevel inverter.
光伏并网逆变器的群控技术%Group control technology of PV grid-connected inverters
Institute of Scientific and Technical Information of China (English)
李春; 王丽萍; 江燕兴
2012-01-01
The grid-connected inverter is a chief device in the PV generation system, and it has significant effect on the operation efficiency of the generation system. Group control strategy can improve the PV system efficiency prominently. This paper introduces the concept of the group control strategy in detail first. After that a comparison experiment is carried out between a PV generation system constructed of ordinary grid-connected inverters and a system constructed of group control grid-connected inverters. The actual output data of the two systems are recorded and analyzed. The experiment proves that the group control strategy can improve the system efficiency.%并网逆变器作为光伏发电系统的核心装置,对系统的运行效率有重要影响.群控技术是一种有效提高系统运行效率的手段.文章首先对群控技术进行了详细的描述,随后对采用具有群控功能的逆变器构成的发电系统与采用常规逆变器构成的发电系统的实际发电量进行了统计与分析.实际运行结果表明,群控技术可以在一定程度上提高系统发电量.
Energy Technology Data Exchange (ETDEWEB)
Lundstrom, Blake [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2017-05-08
Google is encouraging development of advanced photovoltaic inverters with high power density by holding a public competition and offering a prize for the best performing high power developed. NREL will perform the performance and validation for all inverters entered into the competition and provide results to Google.
A flexible five-level cascaded H-bridge inverter for photovoltaic gird-connected systems
DEFF Research Database (Denmark)
Sun, Bo; Wu, Fengjiang; Savaghebi, Mehdi
2015-01-01
With the rapid penetration of photovoltaic (PV) grid-connected system in industrial and commercial application, it is critical to improve the efficiency and enhance the utilization of PV power generation system. This paper proposes a flexible five-level topology based on cascaded multi-level inve......With the rapid penetration of photovoltaic (PV) grid-connected system in industrial and commercial application, it is critical to improve the efficiency and enhance the utilization of PV power generation system. This paper proposes a flexible five-level topology based on cascaded multi...... of PV arrays are lower, the proposed inverter works in CMI mode to widen the generation range. When output voltages of PV panels are higher, inverter works in HBI mode to increase the efficiency. Hence the system incorporate the low losses feature of HBI and low grid-connected current THD advantages...
Berger, Carolin; Robin, Guillaume P; Bonas, Ulla; Koebnik, Ralf
2010-07-01
Type III secretion (T3S) systems play key roles in the assembly of flagella and the translocation of bacterial effector proteins into eukaryotic host cells. Eleven proteins which are conserved among gram-negative plant and animal pathogenic bacteria have been proposed to build up the basal structure of the T3S system, which spans both inner and outer bacterial membranes. We studied six conserved proteins, termed Hrc, predicted to reside in the inner membrane of the plant pathogen Xanthomonas campestris pv. vesicatoria. The membrane topology of HrcD, HrcR, HrcS, HrcT, HrcU and HrcV was studied by translational fusions to a dual alkaline phosphatase-beta-galactosidase reporter protein. Two proteins, HrcU and HrcV, were found to have the same membrane topology as the Yersinia homologues YscU and YscV. For HrcR, the membrane topology differed from the model for the homologue from Yersinia, YscR. For our data on three other protein families, exemplified by HrcD, HrcS and HrcT, we derived the first topology models. Our results provide what is believed to be the first complete model of the inner membrane topology of any bacterial T3S system and will aid in elucidating the architecture of T3S systems by ultrastructural analysis.
High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation
DEFF Research Database (Denmark)
Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick
2017-01-01
This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...
Analysis and Modeling of Transformerless Photovoltaic Inverter Systems
DEFF Research Database (Denmark)
Kerekes, Tamas
demands. This continuously increasing consumption overloads the distribution grids as well as the power stations, therefore having a negative impact on power availability, security and quality. One of the solutions for overcoming this is the grid-connected photovoltaic (PV) system. PV inverter systems can...... panels and pose safety problems. The major task of this research was the investigation and verification of trans-formerless topologies and control strategies to minimize the leakage current of PV inverter topologies in order to comply with the standard requirements and make them safe for human...... of several commercial mono- and multi-crystalline PV panels has been measured, and an appropriate value has been defined for use in the simula-tions. Also, two commercial current sensors that can be used for leakage current measurement, have been tested and the results are presented in Appendix A. A detailed...
Apolication of Hysteresis SVPWM Control in PV Grid-connected Inverter%滞环SVPWM控制在光伏并网逆变器中的应用
Institute of Scientific and Technical Information of China (English)
李畸勇; 龚仁喜; 韦海燕
2011-01-01
由于光伏并网发电系统有许多优点,这里在两级式光伏并网发电系统的基础上,分析了滞环空间矢量脉宽调制电流控制原理,并将其应用于光伏并网发电系统的逆变器控制,以此来提高光伏发电并网控制的动态响应和并网电流质量.建立了系统仿真模型和相应的实验平台,仿真和实验结果表明了该控制方法的有效性,能较好地满足光伏并网控制的要求.%Because photovoltaic (PV) grid-connected power system has many advantages,based on two state PV gridconnected power system, the hysteresis SVPWM current control theory is analyzed and proposed to apply in the inverter control of PV grid-connected power system. In order to improve the dynamic response of grid-connected control and grid-connected current quality. The system simulation model and the corresponding experimental platform are established ,simulation and experiment are carried out at the same time. The results show that the control method can satisfy the requirement of PV grid-connected power system.
Leakage current analysis of a single-phase transformer-less PV inverter connected to the grid
DEFF Research Database (Denmark)
Ma, Lin; Tang, F.; Zhou, F.;
2009-01-01
Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance betwee...
Energy Technology Data Exchange (ETDEWEB)
Mozaffari Niapour, S.A.KH., E-mail: s.a.kh.mozaffari.niapour@gmail.com [Faculty of Electrical and Computer Engineering, University of Tabriz, 51664 Tabriz (Iran, Islamic Republic of); Danyali, S.; Sharifian, M.B.B.; Feyzi, M.R. [Faculty of Electrical and Computer Engineering, University of Tabriz, 51664 Tabriz (Iran, Islamic Republic of)
2011-08-15
Highlights: {yields} Employing the BLDC motor in water pumping systems. {yields} Utilizing the ZSI as a single-stage power converter in the PV water pumping systems based on BLDC motor. {yields} Improvement of the conventional IC MPPT method with the fuzzy logic control scheme to save more energy from the PV array. {yields} Taking the advantages of the DTC drive of the BLDC motor. {yields} Optimizing the water pumping system speed response characteristic by PSO. - Abstract: This paper discusses operation performance of a water pumping system consist of a brushless dc (BLDC) motor coupled a centrifugal pump and accompanying a Z-source inverter (ZSI) fed by a photovoltaic (PV) array, to be improved. Despite conventional double-stage power converters, this paper proposes utilizing a single-stage ZSI to extract the maximum power of the PV array and supply the BLDC motor simultaneously. Utilizing the ZSI provides some inherent advantages such as high efficiency and low cost, which is very promising for PV systems due to its novel voltage buck/boost capability. In addition, in order to precisely perform the maximum power point tracking (MPPT) of the PV array the fuzzy logic-incremental conductance (FL-IC) MPPT scheme is proposed. The proposed FL-IC MPPT scheme provides enough modification to the conventional IC method to enjoy an appropriate variable step size MPPT control signal for the ZSI. Moreover, direct torque control (DTC) is found more effective in comparison with hysteresis current control with current shaping to drive the BLDC motor, because it benefits from faster torque response, reduced torque ripple, less sensitivity to parameters variations, and simple implementation. In the mean time, due to the frequently variations of the PV power generation; delivered mechanical power to the centrifugal pump is variable. Thus, the BLDC motor should be driven with variable reference speed. In order to improve the speed transient response of the BLDC motor and enhance
Energy Technology Data Exchange (ETDEWEB)
Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lave, Matthew Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seuss, John [Georgia Inst. of Technology, Atlanta, GA (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States)
2016-01-01
The research presented in this report compares several real - time control strategies for the power output of a large number of PV distributed throughout a large distribution feeder circuit. Both real and reactive power controls are considered with the goal of minimizing network over - voltage violations caused by large amounts of PV generation. Several control strategies are considered under various assumptions regarding the existence and latency of a communication network. The control parameters are adjusted to maximize the effectiveness of each control. The controls are then compared based on their ability to achieve multiple objectiv es. These objectives include minimizing the total number of voltage violations , minimizing the total amount of PV energy curtailed or reactive power generated, and maximizing the fairness of any control action among all PV systems . The controls are simulat ed on the OpenDSS platform using time series load and spatially - distributed irradiance data.
Study on grid-connected control technology of PV inverter%光伏逆变器的并网控制技术研究
Institute of Scientific and Technical Information of China (English)
马尚行; 戴永军; 何金伟
2011-01-01
With the 3-phase 100 kW photovoltaic (PV) grid-connected inverter as the platform, the operating principle and system structure was explained, the grid-connected control technology of the inveder was analyzed, and a soft phase-locked loop (PLL) of vector control based on coordinate conversion and positive-negative sequence separation was proposed. The results of design were given, and the 100 kW PV grid-connected inverter was realized.%以三相100 kW光伏并网逆变器为研究平台,阐述了并网逆变器的工作原理和系统结构,分析了并网逆变器的并网控制技术,提出一种基于坐标变换和正负序分离的矢量控制的软件锁相环技术,并给出了设计结果,实现了100kW光伏逆变器的并网设计.
Institute of Scientific and Technical Information of China (English)
王冰清; 曾国宏; 童亦斌; 张勇波
2013-01-01
The research on output characteristics of photovoltaic (PV) module is the foundation to determine the voltage range at maximum power point (MPP) of grid-connected PV inverter. The mathematical model of PV module is of high accuracy, however considering such disadvantages of the mathematical model such as concerning in transcendental equation, complex solving process and too much input parameters, it is not suitable for engineering design; the calculation of simplified model of PV module is simple, however by which the output characteristics of PV module under low light condition cannot be accurately described. Based on contrastive analysis on the mathematical model and simplified model, an accurate engineering model of PV module, which is benchmarked in the mathematical model, is proposed. The compensation parameters of the simplified model is fitted and modified, meanwhile both accuracy and complexity of engineering model are taken into account. The MathCad program is utilized to built the simulation model of PV module, and the output results of the simulation model is contrasted with the output of the mathematical model to verify the accuracy of accurate engineering model. Based on the proposed engineering model, through analyzing the impacts of external conditions such as illumination, temperature and so on, the voltage range traced at MPP of grid-connected PV inverter can be accurately determined, and the correctness of this conclusion is validated by experimental results.%光伏并网变流器最大功率点(maximum power point， MPP)电压范围的确定是以组件的输出特性研究为基础的。组件的数学模型精确度较高，但涉及到超越方程，求解复杂且输入参数多，不适用于工程设计。简化模型计算过程简单但不能准确表述弱光条件下的组件输出特性。基于对数学模型及简化模型的对比分析，提出了一种精确的工程模型，该模型以数学模型为基准，对简化模型的
The PCHD Model and Control of TNPC PV Grid-connected Inverter%TNPC型光伏并网逆变器的PCHD建模与控制
Institute of Scientific and Technical Information of China (English)
张百乐; 王久和; 赵凤姣
2014-01-01
根据T型中点箝位(T-type neutral point clamped，TNPC)型光伏并网逆变器拓扑结构建立端口受控的耗散哈密顿(port controlled Hamiltonian with dissipation，PCHD)数学模型。基于此数学模型，采用互联和阻尼配置无源控制(interconnection and damping assignment passivity- based control，IDA-PBC)方法设计控制器。介绍三电平空间矢量调制算法的原理及实现方法。仿真结果表明，该文设计的基于PCHD模型的TNPC型光伏并网逆变器无源控制器能够使光伏并网逆变器实现网侧单位功率因数、电流低谐波；同时，使并网逆变器具有良好的动态、静态特性。%ABSTRACT:Based on the control method of energy shaping and port controlled Hamiltonian with dissipation (PCHD), the model of the TNPC (T-type neutral point clamped) PV grid-connected inverter and its control were studied. Based on the model, the controller was designed by using the method of interconnection and damping assignment passivity-based control. It analyzed the principle and realization method of three-level space vector modulation algorithm. Simulation results show that the designed passive controller of TNPC PV grid-connected inverter can achieve unity power factor, the total harmonic distortion of grid-connected current is low, and the controller also makes the inverter have good dynamic and static performances.
PWM Regulation of Grid-Tied PV System on the Base of Photovoltaic-Fed Diode-Clamped Inverters
Directory of Open Access Journals (Sweden)
Oleschuk V.I.
2015-12-01
Full Text Available Investigation of grid-tied photovoltaic system on the base of two diode-clamped inverters, controlled by specific algorithms of pulse-width modulation (PWM, has been done. This system includes two strings of photovoltaic panels feeding two diode-clamped inverters. The outputs of inverters are connected with the corresponding windings on the primary side of three-phase transformer, connected with a grid. In order to reduce phase voltage distortion and to increase efficiency of operation of the system, special scheme of control and modulation of inverters has been used, providing minimization of common-mode voltages and voltage waveforms symmetries under different operating conditions. Detailed simulation of processes in this photovoltaic-fed power conversion system has been executed. The results of simulations verify good performance of photovoltaic system regulated in accordance with specific strategy of control and modulation.
DEFF Research Database (Denmark)
Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum
2014-01-01
To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial...
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede
2016-01-01
This paper proposes a new single-phase flying capacitor transformerless PV inverter for grid-connected photovoltaic (PV) systems. The neutral of the grid can be directly connected to the negative terminal of the source (PV). It consists of four power switches, one diode, one capacitor and a small...... and some topologies, which requires two times of the peak ac-voltage magnitude) and, (5) the flying capacitor charges every switching cycle, which reduces the size of the required capacitor with switching frequency. In addition, industry standard half bridge module can be used in the new inverter without...
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng; Loh, Poh Chiang
2011-01-01
Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system......, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DC converters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second...
Firefighter Safety for PV Systems
DEFF Research Database (Denmark)
Mathe, Laszlo; Sera, Dezso; Spataru, Sergiu
2015-01-01
An important and highly discussed safety issue for photovoltaic (PV) systems is that as long as the PV panels are illuminated, a high voltage is present at the PV string terminals and cables between the string and inverters that is independent of the state of the inverter's dc disconnection switc...
Operational analysis and comparative evaluation of embedded Z-Source inverters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Gao, F.; Loh, P.C.
2008-01-01
) circuitry connected instead of the generic voltage source inverter (VSI) circuitry. Further proceeding on to the topological variation, parallel embedded Z-source inverters are presented with the detailed analysis of topological configuration and operational principles showing that they are the superior......This paper presents various embedded Z-source (EZ-source) inverters broadly classified as shunt or parallel embedded Z-source inverter. Being different from the traditional Z-source inverter, EZ-source inverters are constructed by inserting dc sources into the X-shaped impedance network so...... that the dc input current flows smoothly during the whole switching period unlike the traditional Z-source inverter. This feature is interesting when PV panels or fuel cells are assumed to power load since the continuous input current flow reduces control complexity of dc source and system design burden...
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Borup, Uffe;
2004-01-01
disturbance rejection capability leads to the need of grid feed-forward compensation. However the imperfect compensation action of the feed-forward control results in high harmonic distortion of the current and consequently non-compliance with international standards. In this paper a new control strategy...... aimed to mitigate these problems is proposed. Stationary-frame generalized integrators are used to control the fundamental current and to compensate the grid harmonics providing disturbance rejection capability without the need of feed-forward grid compensation. Moreover the use of a grid LCL......-filter is investigated with the proposed controller. The current control strategy has been experimentally tested with success on a 3 kW PV inverter....
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Agelidis, Vassilios; Teodorescu, Remus
2008-01-01
affects the shape and quality of the injected current. In this paper, an accurate and less-disturbing active method suitable for phase-locked loop (PLL) based controllers is proposed. The PLL structure is built using a second order generalized integrator (SOGI). Each output cycle the inverter current...
Assessment and monitoring of grid-tied PV inverter performance using a “golden inverter” model
DEFF Research Database (Denmark)
Paasch, Kasper; Nymand, Morten; Stöckl, Johannes;
2016-01-01
A method to define a best case behavioral or “golden inverter” software model has been developed, derived from either internal inverter readings (internal), high precision site based measurements or laboratory characterization and well defined conditions. The paper describes the method of the mod...... development as well as the performance of the model for a selected use case....
Assessment and monitoring of grid-tied PV inverter performance using a “golden inverter” model
DEFF Research Database (Denmark)
Paasch, Kasper; Nymand, Morten; Stöckl, Johannes;
2016-01-01
A method to define a best case behavioral or “golden inverter” software model has been developed, derived from either internal inverter readings (internal), high precision site based measurements or laboratory characterization and well defined conditions. The paper describes the method of the model...... development as well as the performance of the model for a selected use case....
DEFF Research Database (Denmark)
Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.
2016-01-01
. The first solution directly replaces the 1200 V primary Si IGBT switches with lower loss 1200 V SiC MOSFETs. The second solution strategically adds 600 V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified...
DEFF Research Database (Denmark)
Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.
2016-01-01
. The first solution directly replaces the 1200V primary Si IGBT switches with lower loss 1200V SiC MOSFETs. The second solution strategically adds 600V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified...
Directory of Open Access Journals (Sweden)
Ningyun Zhang
2014-06-01
Full Text Available The Proportional Resonant (PR current controller provides gains at a certain frequency (resonant frequency and eliminates steady state errors. Therefore, the PR controller can be successfully applied to single grid-connected PV inverter current control. On the contrary, a PI controller has steady-state errors and limited disturbance rejection capability. Compared with the L- and LC filters, the LCL filter has excellent harmonic suppression capability, but the inherent resonant peak of the LCL filter may introduce instability in the whole system. Therefore, damping must be introduced to improve the control of the system. Considering the controller and the LCL filter active damping as a whole system makes the controller design method more complex. In fact, their frequency responses may affect each other. The traditional trial-and-error procedure is too time-consuming and the design process is inefficient. This paper provides a detailed analysis of the frequency response influence between the PR controller and the LCL filter regarded as a whole system. In addition, the paper presents a systematic method for designing controller parameters and the capacitor current feedback coefficient factor of LCL filter active-damping. The new method relies on meeting the stable margins of the system. Moreover, the paper also clarifies the impact of the grid on the inverter output current. Numerical simulation and a 3 kW laboratory setup assessed the feasibility and effectiveness of the proposed method.
Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters
DEFF Research Database (Denmark)
Teodorescu, Remus; Gao, F.; Blaabjerg, Frede;
2007-01-01
To date, designed topologies for dc-ac inversion with both voltage-buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable...
Meo, Santolo; Sorrentino, Vincenzo
2015-03-01
In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy.
A Single-phase Diode Clamped Transformerless PV Grid-connected Inverter%一种二极管无源钳位的单相无变压器型光伏并网逆变拓扑研究
Institute of Scientific and Technical Information of China (English)
王金华; 顾云杰; 胡斯登; 李武华; 何湘宁; 曹丰文
2015-01-01
A single-phase transformerless grid-connected photovoltaic (PV) inverter topology was proposed based on diode clamped method. The proposed circuit provides an effective improvement in common-mode current rejection capability, compared with state-of-the-art dc/ac decoupled solutions such as the H5 topology. In the proposed method, an extra voltage clamped path is inserted in an ac-decoupled transformerless inverter through two passive diodes. As a result, the common-mode voltage is clamped by the dc capacitor to eliminate the possible high-frequency common-mode oscillations caused by power device parasitic capacitors, which is the major cause of leakage current in dc/ac decoupled transformerless topologies. The proposed passive clamped technique features cost effective solution with no additional active switches, in comparison with the active clamping counterpart. The performance of the proposed topology has been verified by simulation and experiment with a 2kW prototype.%提出一种基于二极管无源钳位思想的单相无变压器型光伏并网逆变器拓扑。与H5等传统电路相比，本拓扑具有更好的对地漏电流抑制能力。目前主流的单相无变压器型逆变电路普遍采用直流或交流解耦技术，阻断共模电流的流通路径。但是，功率开关上的寄生电容可能与共模电抗形成谐振回路，使得共模电流无法彻底消除。以H5拓扑为例，定量分析功率器件寄生电容影响共模电流的机理。针对这一问题，引入无源二极管钳位电路，使得共模电压被母线电容中点钳位，从而抑制了功率器件寄生电容引起的共模电压振荡，更有效地消除对地漏电流。在理论和仿真分析的基础上，通过搭建2 kW实验平台验证所提拓扑的性能。结果表明，改进拓扑相对于原拓扑而言，能更好地抑制对地漏电流，提高了无变压器型光伏并网系统的安全裕度。
DEFF Research Database (Denmark)
Liu, Hongpeng; Yang, Yongheng; Wang, Xiongfei
2016-01-01
generation) due to the intermittency. In that case, unbalance in active power generation may occur among the paralleled systems. Additionally, most droop-controlled systems have been assumed to be a single dc-ac inverter with a fixed dc input source. The dc-dc converter as the front-end of a two......Traditional droop-controlled systems assume that the generators are able to provide sufficient power as required. This is however not always true, especially in renewable systems, where the energy sources (e.g., photovoltaic source) may not be able to provide enough power (or even loss of power...... strategy is carried out. Experiments have verified the effectiveness of the proposed droop control scheme....
DEFF Research Database (Denmark)
Será, Dezsö; Kerekes, Tamas; Lungeanu, Marian
2005-01-01
of the P+Resonant controller with selective harmonic compensation on a low-cost fixed-point DSP. The resonant part of the P+R has been implemented as a second order filter based on Delta operator. The current controller, together with harmonic compensation for the 3rd, 5th, and 7th harmonics has been......The performances of the P+Resonant controller in case of current control for a single phase grid connected inverter have been proved to be superior to the PI controller, since it is able to remove the phase error of the control at the fundamental frequency of the grid. It offers also...... the possibility of selective harmonic compensation. However, in case of digital implementation on a low-cost fixedpoint DSP, the limited computational power and the limited numerical representation precision can restrict the utilization of it. The present paper proposes a different way of digital implementation...
Sotoodeh, Pedram
This dissertation presents the design of a novel multi-level inverter with FACTS capability for small to mid-size (10-20kW) permanent-magnet wind installations using modular multi-level converter (MMC) topology. The aim of the work is to design a new type of inverter with D-STATCOM option to provide utilities with more control on active and reactive power transfer of distribution lines. The inverter is placed between the renewable energy source, specifically a wind turbine, and the distribution grid in order to fix the power factor of the grid at a target value, regardless of wind speed, by regulating active and reactive power required by the grid. The inverter is capable of controlling active and reactive power by controlling the phase angle and modulation index, respectively. The unique contribution of the proposed work is to combine the two concepts of inverter and D-STATCOM using a novel voltage source converter (VSC) multi-level topology in a single unit without additional cost. Simulations of the proposed inverter, with 5 and 11 levels, have been conducted in MATLAB/Simulink for two systems including 20 kW/kVAR and 250 W/VAR. To validate the simulation results, a scaled version (250 kW/kVAR) of the proposed inverter with 5 and 11 levels has been built and tested in the laboratory. Experimental results show that the reduced-scale 5- and 11-level inverter is able to fix PF of the grid as well as being compatible with IEEE standards. Furthermore, total cost of the prototype models, which is one of the major objectives of this research, is comparable with market prices.
Fault Ride-Through of a Grid-connected Photovoltaic System with Quasi Z Source Inverter
DEFF Research Database (Denmark)
Al-Durra, Ahmed; Fayyad, Yara; Muyeen, S.M.
2016-01-01
This article presents fault ride-through schemes for a three-phase quasi Z source single-stage photovoltaic (PV) inverter that is connected to the grid after the distribution network. The quasi Z source inverter employs a unique LC network to couple the inverter main circuit to the input of the PV...... panel. By controlling the shoot-through duty cycle, the quasi Z source inverter can theoretically produce any desired output AC voltage, even greater than the line voltage. Three different control strategies to improve the low-voltage ride-through capability are proposed when there is voltage sag from...... the grid side so that the grid fault ride-through requirements can be fulfilled. Scheme A involves control modification in the system; Schemes B and C involve hardware modification in the circuit topology by adding a chopper circuit across the DC link in Scheme B and across the quasi Z source inverter...
Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed [GE Global Research Center, Niskayuna, NY (United States)
2015-10-27
The “Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System” program is focused on developing innovative concepts for residential photovoltaic (PV) systems with the following objectives: to create an Innovative micro-inverter topology that reduces the cost from the best in class micro-inverter and provides high efficiency (>96% CEC - California Energy Commission), and 25+ year warranty, as well as reactive power support; integrate micro-inverter and PV module to reduce system price by at least $0.25/W through a) accentuating dual use of the module metal frame as a large area heat spreader reducing operating temperature, and b) eliminating redundant wiring and connectors; and create micro-inverter controller handles smart grid and safety functions to simplify implementation and reduce cost.
Modified impedance source inverter for power conditioning system
Indian Academy of Sciences (India)
J SUGANTHI; M RAJARAM
2017-03-01
Based on classical impedance source inverter concept, this paper presents a modified impedance source inverter controlled by different pulse width modulation control strategies for solar PV/battery-powered applications. A brief topology analysis, generalized discussion and design of impedance network elements are presented. Comparison with the classical impedance source inverter is presented. Using simulation, analytical results are presented that ensure stability. The proposed voltage type inverter has reduced inrush current at startup, less capacitor voltage stress and minimum inductor current ripples. DC link voltage boost, reduced total harmonic distortion of output current and voltage, better voltage gain and wide range of output voltage controlcan be achieved easily with improved power quality. Experimental set-up of the modified impedance source inverter with Field Programmable Gate Array (FPGA) controller has been constructed to ascertain the results.
Directory of Open Access Journals (Sweden)
Luis Gerardo González-Morales
2014-01-01
Full Text Available Este artículo presenta el diseño de un sistema de conversión de energía eléctrica (SCEE para el aprovechamiento de energía solar y luego acondicionamiento e inyección de energía a la red eléctrica comercial. Se utiliza un inversor puente completo monofásico con la topología sin transformador H5 acoplado a un filtro LCL. El sistema es identificado mediante el modelo de estado promediado y de pequeña señal, el esquema de control presenta un control en cascada sintonizado mediante la asignación de polos, además de un algoritmo de seguimiento de máxima potencia de tipo perturbar y observar que permite aumentar la eficiencia del sistema, operando en el punto óptimo de funcionamiento del panel solar. En el diseño se describen aspectos técnicos fundamentales en el dimensionamiento y selección de componentes para su desarrollo experimental, así como el diseño de la estructura de control para un buen desempeño ante perturbaciones del sistema.
Directory of Open Access Journals (Sweden)
Ahmad Alferidi
2017-02-01
Full Text Available The contribution of solar power in electric power systems has been increasing rapidly due to its environmentally friendly nature. Photovoltaic (PV systems contain solar cell panels, power electronic converters, high power switching and often transformers. These components collectively play an important role in shaping the reliability of PV systems. Moreover, the power output of PV systems is variable, so it cannot be controlled as easily as conventional generation due to the unpredictable nature of weather conditions. Therefore, solar power has a different influence on generating system reliability compared to conventional power sources. Recently, different PV system designs have been constructed to maximize the output power of PV systems. These different designs are commonly adopted based on the scale of a PV system. Large-scale grid-connected PV systems are generally connected in a centralized or a string structure. Central and string PV schemes are different in terms of connecting the inverter to PV arrays. Micro-inverter systems are recognized as a third PV system topology. It is therefore important to evaluate the reliability contribution of PV systems under these topologies. This work utilizes a probabilistic technique to develop a power output model for a PV generation system. A reliability model is then developed for a PV integrated power system in order to assess the reliability and energy contribution of the solar system to meet overall system demand. The developed model is applied to a small isolated power unit to evaluate system adequacy and capacity level of a PV system considering the three topologies.
Institute of Scientific and Technical Information of China (English)
潘铭航; 苏秀蓉; 王正仕
2013-01-01
针对使用中央逆变器及组串式逆变器的光伏发电系统中整体太阳能转换效率不高的缺点,提出了将单个太阳能电池板连接一个小功率的逆变器以组成光伏系统,该系统能够使每个太阳能电池板都工作于最大功率点,针对该系统设计了基于反激拓扑的高效率单级并网逆变器,通过电流峰值控制,将太阳能电池板发出的直流电变换成与电网电压幅值匹配的正弦馒头波,再通过工作于工频状态下的晶闸管桥臂换相成正弦交流电,并人电网,锁相采用过零点检测法,最大功率点跟踪(MPPT)算法采用扰动法,给出了控制框图,并搭建了100 W的实验样机.研究结果表明,基于反激拓扑的单级并网逆变器与单个太阳能电池板组成的光伏系统可以有效地提高整个光伏发电系统的太阳能转换效率.%Aiming at raising the efficiency of the whole photovoltaic (PV) generating system, a low-power inverter was introduced to individually mount on each photovoltaic module to form a system. In this system, each PV module can work at the maximum power point. A micro-inverter based on flyback topology using single-stage grid-connected method was proposed for this system. The flyback was controlled to convert the direct current produced by the PV panel into a rectified sine wave through the peak current control,and then a SCR bridge was used to unfold the rectified sine wave to an alternative one. The zero detecting method was used to do the phase lock logic,the perturbation method was used to do the maximum power point tracking(MPPT)of the PV panel and the control block was given. At last,a 100 W prototype was presented. The experiment results show that the flyback based single-staged grid-connected system raises the efficiency of the whole PV generating system.
单相高可靠并网逆变器电路拓扑%Single-phase high-reliability grid-connected inverter topologies
Institute of Scientific and Technical Information of China (English)
姚志垒; 肖岚
2013-01-01
A family of single-phase high-reliability grid-connected inverter topology is proposed to solve the shoot-through problem in conventional bridge-type grid-connected inverters. The proposed grid-connected inverters are deduced from the high-reliability cells. The operating principles of the proposed high-reliability grid-connected inverters with bipolar and unipolar modulations are illustrated. The constituent principle of the high-reliability grid-connected inverters is concluded. The simulation results of a dual-buck full-bridge grid-connected inverter with unipolar modulation verify the theoretical analysis. The comparison between the high-reliability grid-connected inverter and traditional grid-connected inverter shows that the dual-buck half-bridge grid-connected inverter is suitable for 110~120 V grid-voltage applications and the full-bridge type high-reliability grid-connected inverters are promising in 220~240 V grid-voltage applications.%针对传统桥式并网逆变器存在桥臂功率开关管的直通问题，提出了一族单相高可靠并网逆变器电路拓扑。所提并网逆变器是由高可靠性单元相互组合而成。分析了双极性和单极性调制高可靠并网逆变器的工作原理，归纳出了高可靠并网逆变器的构成原则。以单极性双降压全桥并网逆变器为例进行了仿真验证。比较分析了传统并网逆变器和所提高可靠并网逆变器。分析结果表明：双降压半桥并网逆变器适合110~120 V电网电压场合，而全桥型高可靠并网逆变器适合220~240 V电网电压场合。
Design of inverters for the PHOTONERGY project
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-08-01
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into specifications. Based on this 23 topologies were analyzed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Two different solutions were picked up in due to their high efficiency and low cost. 1. The standard full-bridge phase shifted DC/DC converter together with a standard DC/AC inverter, 2. A modified version of the novel Shimizu topology. A patent is pending on this modified version. These two inverters are in this document developed and made ready for prototyping. This includes design and selection of reactive- and switching-components, e.g. filter- and bulk-capacitors, low- and high-frequency inductors, high frequency transformers, MOSFETs and diodes. The design of auxiliary circuits is also included, e.g. gate drivers for the MOSFETs, measuring circuits for the grid-current and -voltage, PV-module-current and voltage, protection circuits, hardware near controllers and finally a switch mode power supply. However, the design of the various controllers, except the hardware near PV-current controller for the full bridge phase shifted converter, is not documented in this report but will come later on. This includes all controllers, e.g. maximum power point tracking for the PV-module, utility grid current controller, DC-link voltage controller, phase locked loops, and detection of islanding operation. All of these control loops are to be implemented in a micro-controller. (au)
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has d...
Lefschetz, Solomon
1930-01-01
Lefschetz's Topology was written in the period in between the beginning of topology, by PoincarÃ©, and the establishment of algebraic topology as a well-formed subject, separate from point-set or geometric topology. At this time, Lefschetz had already proved his first fixed-point theorems. In some sense, the present book is a description of the broad subject of topology into which Lefschetz's theory of fixed points fits. Lefschetz takes the opportunity to describe some of the important applications of his theory, particularly in algebraic geometry, to problems such as counting intersections of
Hocking, John G
1988-01-01
""As textbook and reference work, this is a valuable addition to the topological literature."" - Mathematical ReviewsDesigned as a text for a one-year first course in topology, this authoritative volume offers an excellent general treatment of the main ideas of topology. It includes a large number and variety of topics from classical topology as well as newer areas of research activity.There are four set-theoretic chapters, followed by four primarily algebraic chapters. Chapter I covers the fundamentals of topological and metrical spaces, mappings, compactness, product spaces, the Tychonoff t
Predictive Control Algorithm of PV Grid-connected Inverter Based on MLD Model%光伏并网逆变器MLD建模及预测控制算法
Institute of Scientific and Technical Information of China (English)
路璐; 龚仁喜; 韦潜
2015-01-01
光伏并网逆变器传统的开关函数模型在并网过程中的动态响应速度慢，影响了逆变器溃入电网的电能质量。为了解决这一问题，提高光伏并网逆变器的供电质量，分析光伏并网逆变器的混杂特性，通过对逆变器的开关动态引入逻辑变量，建立MLD模型，提出一种基于该模型的预测控制算法。仿真结果表明，基于MLD模型的预测控制算法改善了光伏并网系统的动态性能，达到并网要求条件的时间更短，验证了所提方法的可行。%The slow respond of the inverter PV grid system based on traditional switching function model affects the power quality feed into the grid. To solve this problem and improve the power quality of the inverter, after analyzing the PV grid-connected in-verter confounding characteristics, by introducing logical variables for the inverter switching dynamics, the MLD model of the sys-tem was built. A predictive control strategy was proposed based on this kind of model. The comparison of simulation results show that the predictive control algorithm on the MLD model can improve the dynamic performance of the system, reduce the time of the system meeting the requirement of the grid, verify the feasibility of the proposed method.
Methodology for the optimal design of tansformerless grid-connected PV interters
DEFF Research Database (Denmark)
Koutroulis, E.; Blaabjerg, Frede
2012-01-01
inverter, such that the PV inverter levelised cost of the generated electricity is minimised. The proposed method constitutes a systematic design process, which is capable to explore the impact of the PV inverter configuration on the trade-off between the PV inverter manufacturing cost and the power losses...
DEFF Research Database (Denmark)
Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum
2015-01-01
The centralized topology with three-level inverters are widely used in photovoltaic (PV) systems due to their less installation costs and complexity. However, the common maximum power point tracking (MPPT) is a disadvantage of the centralized topology particularly under the partial shading...... and panel mismatch conditions. In this system, if PV modules are separately connected to the split capacitor voltage, the MPPT efficiency can be improved by the proposed control strategy. By the proposed method, the two capacitor voltages can be controlled asymmetrically to perform the separate MPPTs...
Kuratowski, Kazimierz
1966-01-01
Topology, Volume I deals with topology and covers topics ranging from operations in logic and set theory to Cartesian products, mappings, and orderings. Cardinal and ordinal numbers are also discussed, along with topological, metric, and complete spaces. Great use is made of closure algebra. Comprised of three chapters, this volume begins with a discussion on general topological spaces as well as their specialized aspects, including regular, completely regular, and normal spaces. Fundamental notions such as base, subbase, cover, and continuous mapping, are considered, together with operations
Kuratowski, Kazimierz
1968-01-01
Topology, Volume II deals with topology and covers topics ranging from compact spaces and connected spaces to locally connected spaces, retracts, and neighborhood retracts. Group theory and some cutting problems are also discussed, along with the topology of the plane. Comprised of seven chapters, this volume begins with a discussion on the compactness of a topological space, paying particular attention to Borel, Lebesgue, Riesz, Cantor, and Bolzano-Weierstrass conditions. Semi-continuity and topics in dimension theory are also considered. The reader is then introduced to the connecte
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed S; Harfman-Todorovic, Maja; Elasser, Ahmed; Steigerwald, Robert L; Sabate, Juan A; Chi, Song; McCann, Adam J; Zhang, Li; Mueller, Frank
2012-09-01
In this paper a DC-DC power converter for distributed photovoltaic plant architectures is presented. The proposed converter has the advantages of simplicity, high efficiency, and low cost. High efficiency is achieved by having a portion of the input PV power directly fed forward to the output without being processed by the converter. The operation of this converter also allows for a simplified maximum power point tracker design using fewer measurements
Institute of Scientific and Technical Information of China (English)
刘桂花; 曹小娇; 王卫
2015-01-01
One of the main electrical characteristics of weak grid is the high grid impedance, which will easily lead to grid voltage waveform distortion. Distorted grid voltage can resultin deviation or failure of the phase-locked loop of photovoltaic (PV) inverter, and power quality will deteriorate. In order to tackle this problem, targeting on the LC-type PV inverter,a synchronization method is proposed based on the second order generalized integrator frequency locked loop (SOGI-FLL). Initially, the impact of various grid states, especially the weak grid, on the inverter is analyzed. Then the operation principle of SOGI-FLL and its implementation method are set forth in detail. Simulation and experimental results demonstrate the validity of this synchronization method in grid voltage disturbance and zero-crossing oscillation. This synchronization method has strong robustness and adaptability for grid voltage changes. Compared with the conventional zero-crossing synchronization method, the SOGI-FLL synchronization method can improve the reliability of grid-connected PV inverters under weak grid.%弱电网的主要电气特性之一为高电网阻抗.高电网阻抗易导致电网电压波形畸变,畸变的电网电压会使光伏并网逆变器锁相环出现偏差甚至失效,并导致并网电能质量变差.针对这一问题,以LC型单相光伏并网逆变器为研究对象,提出采用基于2阶广义积分器锁频环(second order generalized integrator frequency locked loop,SOGI-FLL)同步方法来实现逆变器与弱电网的同步.在分析不同电网状态尤其是弱电网对逆变器影响的基础上,详细阐述SOGI-FLL的工作原理和实现方法.仿真和实验结果表明,该同步方法在电网电压扰动及过零点震荡情况下均可稳定可靠工作,对电网电压变化具有较强的鲁棒性和适应性,与传统过零同步方法相比,SOGI-FLL同步方法可提高弱电网下光伏并网逆变器的可靠性.
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2013-01-01
years) has been set as a main target and an emerging demand from the customers, which imposes a new challenge on grid-connected transformerless inverters. In order to reduce maintenance cost, it is essential to predict the lifetime of the transformerless PV inverter and its components based...... on the mission profiles — solar irradiance and ambient temperature. In this paper, a mission profile based analysis approach is proposed and it is demonstrated by three main single-phase transformerless PV inverters — Full-Bridge (FB) with bipolar modulation scheme, the FB inverter with DC bypass (FB...... by considering the mission profiles. The lifetimes of these topologies are discussed according to the thermal performance and the power losses on the switching devices are also compared....
Institute of Scientific and Technical Information of China (English)
马红梅; 李鹏; 黄成玉
2011-01-01
提出了基于16位单片机SPMC75F2413A的光伏并网系统软硬件的设计方案,系统以SPMC75F2413A作为主控芯片来控制单相桥式逆变主电路.在实现太阳能电池最大功率点跟踪的同时,该系统能实时检测太阳能电池输出电压和电流、电网电压和负载电流,采用软件锁相技术使输出电压同步跟踪电网相电压的频率和相位.通过对光伏并网系统的测试表明:并网电压与电网相电压同频同相.实验结果验证了该系统的可行性和实用性.%A software and hardware design method of PV grid control system based on a 16-bit microcontroller SPMC75F2413A was proposed. The SPMC75F2413A chip is used as main control chip to control single-phase bridge inverter main circuit. The system can track maximum power point of PV panels simultaneously by detecting PV output voltage and current,grid voltage and load current, at the same time make frequency and phase of the inverter output voltage to track grid phase voltage's by the software PLL technique. Test results of simulation system show that grid-connected voltage is synchronization with grid phase voltage. Experimental results show the system is feasibility and practicality.
Institute of Scientific and Technical Information of China (English)
王善生
2016-01-01
电网发生不对称故障时，电网电压中存在的负序分量会对光伏并网控制造成影响。为了消除逆变器交流侧电流和直流侧电压的谐波，采用了正、负序独立旋转坐标系的控制方法，做了基于光伏三电平逆变器的电网不平衡情况下的并网控制策略仿真。仿真结果表明采用正、负序独立旋转坐标系的控制方法，逆变器交流侧电流和直流侧电压的谐波得到有效抑制。%When an unbalanced fault occurs in the power grid,PV grid connection will be affected by the negative sequence component existing in the grid voltage.To eliminate harmonics of the current on the inverter AC side and the voltage on its DC side,grid connection control strategy is simulated under unbalanced grid conditions based on the 3-level PV inverter by adopting a coordinate system with independently rotating positive and negative sequences.Simulation results show that this approach can effectively suppress the harmonics of the current on the inverter AC side and the voltage on its DC side.
Institute of Scientific and Technical Information of China (English)
丰瀚麟; 肖华锋; 谢少军
2011-01-01
The calculation method of flyback-type current source inverter for grid-connected PV systems was studied. The formula for losses calculating was derived. It shows the losses of flyback-type inverter has the close relationship with transformer turns-ratio. Different turns ratio impacts the choice of switch devices, design of transformer, and the converter efficiency ultimately. Based on the analysis of losses model, an optimal design of a 160W grid-connected PV module was achieved. The experiment results validate that the method can provide an effective design method for flyback-type current source inverter, and optimize the system parameters.%研究了反激型电流源光伏并网逆变器损耗的计算方法,推导出用于损耗分析计算的公式.分析表明:反激型电流源并网逆变器的损耗与其变压器匝比关系密切,匝比直接影响开关器件的选择与变压器的设计,最终影响变换器效率.在对其损耗分析模型进行验证的基础上,应用该模型进行了一个160W光伏并网逆变模块的优化设计,实验证明该方法能够为反激型并网逆变器的设计提供一套有效的设计方法,达到优化系统参数的目的.
PSCAD Modules Representing PV Generator
Energy Technology Data Exchange (ETDEWEB)
Muljadi, E.; Singh, M.; Gevorgian, V.
2013-08-01
Photovoltaic power plants (PVPs) have been growing in size, and the installation time is very short. With the cost of photovoltaic (PV) panels dropping in recent years, it can be predicted that in the next 10 years the contribution of PVPs to the total number of renewable energy power plants will grow significantly. In this project, the National Renewable Energy Laboratory (NREL) developed a dynamic modeling of the modules to be used as building blocks to develop simulation models of single PV arrays, expanded to include Maximum Power Point Tracker (MPPT), expanded to include PV inverter, or expanded to cover an entire PVP. The focus of the investigation and complexity of the simulation determines the components that must be included in the simulation. The development of the PV inverter was covered in detail, including the control diagrams. Both the current-regulated voltage source inverter and the current-regulated current source inverter were developed in PSCAD. Various operations of the PV inverters were simulated under normal and abnormal conditions. Symmetrical and unsymmetrical faults were simulated, presented, and discussed. Both the three-phase analysis and the symmetrical component analysis were included to clarify the understanding of unsymmetrical faults. The dynamic model validation was based on the testing data provided by SCE. Testing was conducted at SCE with the focus on the grid interface behavior of the PV inverter under different faults and disturbances. The dynamic model validation covers both the symmetrical and unsymmetrical faults.
DC-DC Converter Topology Assessment for Large Scale Distributed Photovoltaic Plant Architectures
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed S; Harfman-Todorovic, Maja; Elasser, Ahmed; Sabate, Juan A; Steigerwald, Robert L; Jiang, Yan; Essakiappan, Somasundaram
2011-07-01
Distributed photovoltaic (PV) plant architectures are emerging as a replacement for the classical central inverter based systems. However, power converters of smaller ratings may have a negative impact on system efficiency, reliability and cost. Therefore, it is necessary to design converters with very high efficiency and simpler topologies in order not to offset the benefits gained by using distributed PV systems. In this paper an evaluation of the selection criteria for dc-dc converters for distributed PV systems is performed; this evaluation includes efficiency, simplicity of design, reliability and cost. Based on this evaluation, recommendations can be made as to which class of converters is best fit for this application.
Manetti, Marco
2015-01-01
This is an introductory textbook on general and algebraic topology, aimed at anyone with a basic knowledge of calculus and linear algebra. It provides full proofs and includes many examples and exercises. The covered topics include: set theory and cardinal arithmetic; axiom of choice and Zorn's lemma; topological spaces and continuous functions; connectedness and compactness; Alexandrov compactification; quotient topologies; countability and separation axioms; prebasis and Alexander's theorem; the Tychonoff theorem and paracompactness; complete metric spaces and function spaces; Baire spaces; homotopy of maps; the fundamental group; the van Kampen theorem; covering spaces; Brouwer and Borsuk's theorems; free groups and free product of groups; and basic category theory. While it is very concrete at the beginning, abstract concepts are gradually introduced. It is suitable for anyone needing a basic, comprehensive introduction to general and algebraic topology and its applications.
Three-phase multilevel solar inverter for motor drive system
Bhasagare, Mayuresh P.
This thesis deals with three phase inverters and the different control strategies that can be associated with an inverter being used together. The first part of this thesis discusses the present research in the fields of PV panels, motor drive systems and three phase inverters along with their control. This control includes various strategies like MPPT, Volts-Hertz and modulation index compensation. Incorporating these techniques together is the goal of this thesis. A new topology for operating an open end motor drive system has also been discusses, where a boost converter and a flyback converter have been used in cascade to run a three phase motor. The main advantage of this is increasing the number of levels and improving the quality of the output voltage, not to mention a few other benefits of having the proposed circuit. A new algorithm has also been designed for starting and stopping the motor, which controls the current drawn from the power source during starting.
Institute of Scientific and Technical Information of China (English)
王卫; 刘鸿鹏; 吴辉
2015-01-01
An experiment instructional platform of grid-connected PV inverters based on ARM and LabVIEW is pro-posed in this paper,which can be applied in the graduation design of undergraduate class. First,the input/ output information of grid-connected inverters and the grid information are sampled through Arm. Then,the sampled data is processed and displayed through LabVIEW. Finally,the real-time monitoring of PV power generating units is a-chieved. Through the establishment and study of this platform,students can enhance the comprehension and appli-cation of the ARM sampling process and the LabVIEW data display technology.%本文提出了一种基于 ARM 和 LabVIEW 的光伏并网逆变检测系统实验教学平台，应用在本科生毕业设计中。该平台首先通过 ARM 对并网逆变器的输入/输出和电网信息进行采样，然后经过 LabVIEW 对采集数据进行处理与显示，最终实现对光伏发电单元的实时监测。通过平台的搭建和学习，学生可以强化对 ARM 数据采集和 LabVIEW 数据显示技术的理解及应用。
The Application of Single-phase Inverter in PV System%单相逆变器在PV发电系统的应用
Institute of Scientific and Technical Information of China (English)
张淼; 吴捷; 冯垛生
2002-01-01
描述和设计了一个用于PV(光伏)发电系统与民用电网相连接的实用单相逆变控制系统,它能在PV系统能量不足时,利用电网能源进行弥补,PV系统能量过剩时,把能量反馈到电网.给出了系统的试验曲线.
Institute of Scientific and Technical Information of China (English)
周林; 晁阳; 廖波; 晁朋飞; 杨明
2013-01-01
为解决光伏接入电网引起的并网点电压越限问题，增大光伏在电网中的渗透率，可充分利用并网光伏逆变器的无功调压能力向电网提供无功支撑。为此，从电网电压降落角度研究光伏发电接入电网前后并网点电压的变化，并深入分析了德国电气工程师协会(Verband Deutscher Elektrotechniker)提出的无功功率控制策略，在此基础上，提出一种基于并网点电压幅值与光伏有功出力的 Q(U,P)无功功率控制策略。该控制策略继承了德国电气工程师协会提出的策略的优点，在此控制策略下，光伏系统所有逆变器参与电网电压调节，在维持电网电压在要求范围的前提下，无功吸收总量最低，电网有功、无功损耗最小。算例结果验证了该策略的有效性。%In allusion to out-of-limit voltage at grid-connected point caused by grid-connection of photovoltaic (PV) system and raising the penetration rate of PV system on power grid, it is possible to fully utilize the reactive power regulation ability of grid-connected PV inverter to provide reactive power support to power grid. For this purpose, in the viewpoint of voltage drop the voltage variation at grid-connected point before and after the grid-connection of PV system is researched, and the reactive power control strategy given by Verband Deutscher Elektrotechniker (VDE) is analyzed in depth. On this basis, a reactive power control strategy based on voltage amplitude at grid-connected point and active output of PV system is proposed. This control strategy inherits the advantages of reactive power control strategy given by VDE, and under the proposed control strategy all PV inverters participate power grid voltage regulation, and under the premise of maintaining the grid voltage within the specified range the total absorbed amount of reactive power is the lowest and the active and reactive loss of power grid are minimized. The validity of the
基于自整定Fuzzy-PI控制的电流跟踪型光伏并网逆变器%CURRENT TRACKING PV INVERTER BASED ON SELF-TUNING FUZZY-PI CONTROL
Institute of Scientific and Technical Information of China (English)
胡晓青; 程启明; 王映斐; 汪明媚
2013-01-01
An unipolar grid-connected inverter was presented,which possesses the advantage such as low loss,small harmonics,small electromagnetic interference etc.comparing with bipolar inverter,more suitable for on-grid inverter control.Firstly,the DC/DC converter was modeled,then self-tuning Fuzzy-PI control strategy was put forward,which integrating fuzzy self-tuning control theory with PID control law,the direct current produced by solar panels was inverted into the sinusoidal AC 220V/50Hz to provide to the grid.Finally,Matlab simulation model for current tracking PV inverter was completed based on the Fuzzy self-tuning PI control.The results show that the generated PWM control signal based on the method can effectively reduce the tracking error of traditional PID control and quickly track the target and net current waveform to improve the system' s dynamic response.%介绍了一种单极性并网逆变器,相对于双极性并网逆变器具有损耗低、谐波小、电磁干扰小的优势,更适用于并网逆变控制.首先对DC/DC变换器进行建模,随后提出一种将模糊自整定控制理论融合PID控制规律之中的自整定Fuzzy-PI控制策略,将太阳电池板产生的直流电逆变为220V/50Hz的正弦交流电提供给电网,最后建立了基于Fuzzy自整定PI控制的电流跟踪型光伏并网逆变器完整的Matlab仿真模型.仿真结果表明,基于该方法生成的PWM控制信号较之传统PID控制等可有效减小跟踪误差,并迅速跟踪目标并网电流波形,从而提高系统的动态响应性能.
PV grid-connected inverter based on voltage oriented-direct power control%基于电压定向直接功率控制的光伏并网逆变器
Institute of Scientific and Technical Information of China (English)
柴文野; 祝龙记
2012-01-01
The direct power control based on voltage oriented (V-DPC) was applied to a PV grid-connected inverter control strategy and the concept of estimation of the grid voltage and instantaneous power was introduced, taking the instantaneous active power and reactive power with the grid-connected inverter output as the controlled variables for power direct closed-loop control. The system need not to detect the transformer secondary voltage, the grid voltage sensor was omitted, and consequently the shortage of current control scheme was not only overcome, but also the cost was reduced. The system had the advantages of good robustness and simple control structure. The principle of voltage oriented-direct power control was analyzed, the specific parameters of the inverter were designed, and the simulation and experiment results were given.%将基于电压定向直接功率控制用于光伏并网逆变器的控制策略,引入电网电压和瞬时功率的估算概念,并将并网逆变器输出的瞬时有功功率和无功功率作为被控量进行功辜的直接闭环控制.系统无需检测输入变压器二次侧的电网电压,省去了电网电压传感器,从而不仅克服了电流控制方案的不足问题,还降低了成本,而且系统具有鲁棒性好、控制结构简单等优点.分析了电压定向直接功率控制的原理,设计了并网逆变器的具体参数,并给出了仿真和实验结果.
Institute of Scientific and Technical Information of China (English)
王晓雷; 王卫星; 路进升; 王国军; 周笑
2011-01-01
An engineering calculation method for PV (photovoltaic army) array characteristic is proposed, which can calculate the output characteristics of the PV array using the technical parameter ofphotovoltaic cell, total series-units and parallel-branch number of photovoltaic array, and local intensity and temperature. Model ofphotovoltaic array based on MATLAB/simulink is established, and the characteristic curve of the PV array is analysed in detail. Based on the proposed algorithm, the construction and features of the testing system of the first set of PV grid-connected inverter (developed by XJ Group Corporation and Yunnan Power Grid Corporation) are presented. Then some parameters of the inverter (AURORA-PVI-5000-OUTD) are tested by this method. The test results dovetails with original data aimostly, which verifies the correctness and practicability of this method.%提出了一种光伏阵列特性的工程计算方法,基于光伏电池组件的基本技术参数、光伏阵列总的串联单元数和并联支路数、以及现场光照强度和温度,即可得出光伏阵列的特性.以Matlab/Simulink为工具建立仿真模型,详细分析了光伏阵列的特性曲线.以该计算方法为理论基础,介绍了国内第一套光伏并网逆变器测试系统的构成及特点.以此为平台,对型号为AURORA-PVI-5000-OUTD逆变器性能进行了测试,并给出部分测试结果,与该逆变器出厂检测参数基本吻合,验证了该方法的正确性和实用性.
An enhanced Z-source inverter topology-based permanent magnet brushless DC motor drive speed control
Geno Peter, P.; Rajaram, M.
2015-08-01
In this paper, an enhanced Z-source inverter (ZSI) is introduced for controlling the speed of permanent magnet brushless DC motor (PMBLDCM) drive. It is the extension of the conventional ZSI and the elements used in the circuit are the same as those of the conventional ZSI, except that the position of Inverter Bridge and diode would be exchanged from the classical circuit diagram. This exchanged circuit avoids the startup path of the inrush current and hence reduces the inrush current and improves the motor efficiency. Different modes of enhanced ZSI are studied with PMBLDCM. The voltage polarity of Z-source capacitors in the proposed circuit is the same as that of the input voltage polarity. Furthermore, to get the same voltage boost, the capacitor voltage stress is reduced to a significant extent. The speed control capability of the proposed brushless DC motor drive is compared with that of the conventional ZSI. The proposed ZSI is implemented in MATLAB/Simulink working platform and the output performance is evaluated. Also, the performance of voltage ratio is analysed both by simulation and mathematical models. All these analyses are known to express the innovative features of the proposed system.
Khayamy, Mehdy; Ojo, Olorunfemi
2015-04-01
A current source inverter fed from photovoltaic cells is proposed to power an autonomous load when operating under either power regulation or voltage and frequency drooping modes. Input-output linearization technique is applied to the overall nonlinear system to achieve a globally stable system under feasible operating conditions. After obtaining the steady-state model that demarcates the modes of operation, computer Simulation results for variations in irradiance and the load power of the controlled system are generated in which an acceptable dynamic response of the power generator system under the two modes of operation is observed.
Design of a Wide-input Auxiliary Power Supply in the PV Inverter System%一种光伏并网系统用的宽输入辅助电源设计
Institute of Scientific and Technical Information of China (English)
胡天友; 张晓博; 王海; 刘洋
2012-01-01
根据光伏并网逆变系统的供电需求,设计了一种120 ～ 850 V宽输入的辅助电源.为防止在输入电压过高时丢失开通脉冲,在传统的单端反激式拓扑电路的基础上加入了变频电路.输入电压升高时,降低开关频率,保证导通时间大于开关管的最小导通时间,实现了宽输入范围电压的要求.采用DCM工作模式,峰值电流控制,在反馈电路中加入了2型补偿网络,保证了输出电压快速调节性和稳定性.样机实验结果表明,该电源能够适应输入电压在大范围波动,可靠地为光伏并网实验系统供电.%According to the requirement of the PV grid-connected inverter system, an auxiliary power supply with an input voltage of 120 -850 V is designed. To avoid losing the opening pulse at a high input voltage, a circuit that can change switching frequency based on the input voltage is introduced. The peak current control and DCM work mode is used, and the type-2 compensation circuit in the feedback loop guarantees the rapid adjustment of output voltage and stability of the system. Experimental results show that this auxiliary power supply can adapt to a wide fluctuation of input voltage and provide long-term reliable DC voltage to the PV system.
Design of standalone PV inverter based on low voltage and fluctuation input%基于波动低压输入的独立光伏逆变器的设计
Institute of Scientific and Technical Information of China (English)
吴巍
2013-01-01
For lower voltages and fluctuated inputs of a standalone Photovoltaic (PV) inverter, a disturbance-rejection system with a double-closed-loop control was proposed. On the basis of the working principle of the system, the main parts of the inverter were modeled and a overall mathematical model was obtained. The inverter with an input voltage of 24 V, an output voltage of 311 V, a frequency of 50 Hz and an output power of 6 kW was illustrated as an example. In the design, the pole assignment method was used to calculate the controller parameters and the relation between fluctuation input and steady state error was described quantitatively. The simulation result indicates that the system with good stability and low steady state error can reject the disturbance. Its voltage change is 0. 03%, total Harmonic Distortion(THD) is 1. 03% ,and the highest single harmonic content is less than 3% , which meets the requirements as well. The model and design method with theoretical guidance meaning is u-niversal and can support the applications and design of high power inverters in other special fields of PV generation.%针对独立光伏逆变器输入电压较低且波动的问题,提出一种采用双闭环控制策略且抗输入电压扰动的光伏逆变器系统.在阐述其工作原理基础上,对光伏逆变器主要部件进行建模,得到总体数学模型,并举例设计了输入电压为24V、输出为311 V、输出频率为50 Hz、输出功率为6 kW的光伏逆变器.设计中采用极点配置进行控制器参数计算,定量描述了输入电压波动对逆变器跟踪误差的影响.仿真结果表明,设计的逆变器具有稳定性好、抗扰动性强和稳态误差低等特点,其电压变化率为0.03％,输出电压总谐波失真(THD)为1.03％,最高单次谐波含量小于3％,可以满足性能指标要求.所建模型和设计方法具有一定通用性和理论指导意义,可用于特殊光伏发电领域中大功率光伏逆变器的研究与设计.
2009-01-01
This paper applies a dynamical electrical array reconfiguration (EAR) strategy on the photovoltaic (PV) generator of a grid-connected PV system based on a plant-oriented configuration, in order to improve its energy production when the operating conditions of the solar panels are different. The EAR strategy is carried out by inserting a controllable switching matrix between the PV generator and the central inverter, which allows the electrical reconnection of the available PV modules. A...
并网光伏逆变器闪变特性测量与分析%Measurement and analysis on flicker characteristic of grid-connected PV inverter
Institute of Scientific and Technical Information of China (English)
董玮; 黄晶生; 徐亮辉; 郭重阳
2015-01-01
辐照度变化和并网光伏逆变器启停机引起的功率波动都可能会引起并网点电压闪变。文章首先分析了闪变与并网点短路容量、阻抗角度及并网功率波动大小的关系，并基于Matlab／Simulink 软件搭建了虚拟电网模型和数字闪变测试仪模型。针对目前广泛使用的500 kW光伏逆变器开展了不同运行功率和启停机工况下的测试，测量不同工况下该逆变器引起的闪变大小，并对测量结果进行了对比分析。%Power fluctuation caused by irradiance changes , inverter cut-in and cut-off may cause flicker at the grid-connected point .The connection between the flicker and grid short-circuit capacity , grid impedance angle and power change amount is analyzed .And the flicker is tested on a 500 kW photovoltaic ( PV ) inverter at different load and switch operation .Based on the virtual gird model and the flicker meter model developed on Matlab /Simulink platform , the flicker results are tested and analyzed under these operation conditions .
Kuo, Yung-Chih; Chung, Chiu-Yen
2012-12-01
The neuronal differentiation of induced pluripotent stem (iPS) cells in scaffolding biomaterials is an emerging issue in nervous regeneration and repair. This study presents the production of neuron-lineage cells from iPS cells in inverted colloidal crystal (ICC) scaffolds comprising alginate, poly(γ-glutamic acid) (γ-PGA), and TATVHL peptide. The ability of iPS cells to differentiate toward neurons in the constructs was demonstrated by flow-cytometeric sorting and immunochemical staining. The results revealed that hexagonally arrayed microspheres molded alginate/γ-PGA hydrogel into ICC topology with adequate interconnected pores. An increase in the quantity of surface TATVHL peptide enhanced the atomic ratio of nitrogen and the adhesion efficiency of iPS cells in constructs. However, the effect of TATVHL peptide on the viability of iPS cells was insignificant. The adhesion and viability of iPS cells in ICC constructs was higher than those in freeform ones. TATVHL peptide raised the percentage of β III tubulin-identified cells differentiating from iPS cells, indicating that TATVHL peptide stimulated the neuronal development in alginate/γ-PGA ICC constructs. TATVHL peptide-grafted alginate/γ-PGA ICC scaffolds can be promising for establishing nerve tissue from iPS cells.
Design of the Parameters of Inverter Based on PV Cell Characteristic%基于光伏电池特性的逆变器参数设计
Institute of Scientific and Technical Information of China (English)
陈国栋; 朱胤
2014-01-01
According to the V-I operating characteristics curve of cells to select the main circuit capacitance and inductance parameters, both can meet the performance requirements, but it is reasonable to reduce costs.Using power and voltage relationship of solar cells groups in different light under different temperatures, the calculated curve of capacitance and inductance parameters are derived,thus reasonable parameter values of capacitance and inductance are determined. This parameter selection method provides a basis for the actual photovoltaic inverter engineering design.%根据电池电压－电流（V－I ）的工作特性曲线来选择主回路中的电容及电感参数，既满足了性能指标要求，又可以合理地降低成本。运用电池板在不同光照、不同温度下功率和电压的关系，得出电容和电感的参数计算曲线，从而确定了电容和电感的合理参数值。此参数选择方法为实际的光伏逆变器工程设计提供了依据。
A study of the evolution of inverted-topology repeats from LeuT-fold transporters using AlignMe.
Khafizov, Kamil; Staritzbichler, René; Stamm, Marcus; Forrest, Lucy R
2010-12-21
X-ray crystal structures have revealed that numerous secondary transporter proteins originally categorized into different sequence families share similar structures, namely, the LeuT fold. The core of this fold consists of two units of five transmembrane helices, whose conformations have been proposed to exchange to form the two alternate states required for transport. That these two units are related implies that LeuT-like transporters evolved from gene-duplication and fusion events. Thus, the origins of this structural repeat may be relevant to the evolution of transport function. However, the lack of significant sequence similarity requires sensitive sequence search methods for analyzing their evolution. To this end, we developed a software application called AlignMe, which can use various types of input information, such as residue hydrophobicity, to perform pairwise alignments of sequences and/or of hydropathy profiles of (membrane) proteins. We used AlignMe to analyze the evolutionary relationships between repeats of the LeuT fold. In addition, we identified proteins from the so-called DedA family that potentially share a common ancestor with these repeats. DedA domains have been implicated in, e.g., selenite uptake; they are found widely distributed across all kingdoms of life; two or more DedA domains are typically found per genome, and some may adopt dual topologies. These results suggest that DedA proteins existed in ancient organisms and may function as dimers, as required for a would-be ancestor of the LeuT fold. In conclusion, we provide novel insights into the evolution of this important structural motif and thus potentially into the alternating-access mechanism of transport itself.
Lightweight IMM PV Flexible Blanket Assembly
Spence, Brian
2015-01-01
Deployable Space Systems (DSS) has developed an inverted metamorphic multijunction (IMM) photovoltaic (PV) integrated modular blanket assembly (IMBA) that can be rolled or z-folded. This IMM PV IMBA technology enables a revolutionary flexible PV blanket assembly that provides high specific power, exceptional stowed packaging efficiency, and high-voltage operation capability. DSS's technology also accommodates standard third-generation triple junction (ZTJ) PV device technologies to provide significantly improved performance over the current state of the art. This SBIR project demonstrated prototype, flight-like IMM PV IMBA panel assemblies specifically developed, designed, and optimized for NASA's high-voltage solar array missions.
Institute of Scientific and Technical Information of China (English)
陈新; 张旸; 王赟程
2014-01-01
大量存在的并网逆变器会对分布式发电系统的电能质量和系统稳定性造成深刻影响，该文基于阻抗分析方法研究光伏并网逆变器与电网间的交互影响。论文定量分析光伏并网逆变器与电网之间由于阻抗交互影响所产生的谐波振荡，并通过基于硬件在环的分布式发电综合实验平台验证不同电网接入条件对并网逆变器稳定性的影响；推导LCL型并网逆变器的系统阻抗模型，并提出一种基于电压前馈的主动阻抗控制策略来提高逆变器与电网之间的稳定相角裕度，使光伏并网逆变器在不同的动态电网条件下均具有较好的控制鲁棒性；最后给出阻抗主动调整控制策略的设计过程和参数设计方法，并通过仿真验证主动阻抗控制策略的有效性。%The power quality and system stability in Distributed Generation (DG) systems are important issues with the far-ranging application of grid-connected inverters. The study of the dynamic interaction between PV Grid-Connected inverters and the grid based on impedance analysis was presented in this paper. The harmonic resonance due to the impedance interaction between PV inverters and the grid was analyzed in quantity, and the effect of the grid impedance on the stability of PV inverters was evaluated through the hardware-in-loop DG test-bed system. The impedance modeling of LCL type PV inverter was derived in the paper. In order to increase the phase margin of the impedance ratio, a novel active impedance control was proposed, which is beneficial to improve control robustness of PV inverters under different grid impedance conditions. The operation principle and design of the active impedance control were depicted, and the control performance was verified by the simulation evaluation.
Directory of Open Access Journals (Sweden)
Nagarathna M
2015-06-01
Full Text Available Solar energy the most efficient, eco-friendly and abundantly available energy source in the nature. It can be converted into electrical energy in cost effective manner. In recent years, the interest in solar energy has risen due to surging oil prices and environmental concern. In many remote or underdeveloped areas, direct access to an electric grid is impossible and a photovoltaic inverter system would make life much simpler and more convenient. With this in mind, it is aimed to design, build, and test a solar panel inverter. This inverter system could be used as backup power during outages, battery charging, or for typical household applications. The main components of this solar system are solar cell, dc to dc boost converters, and inverter. Sine wave push pull inverter topology is used for inverter. In this topology only two MOSFETs are used and isolation requirement between control circuit and power circuit is also less which helps to decrease the cost of solar inverter.
Techniques for the optimal design of photovoltaic inverters interconnected with the electric grid
DEFF Research Database (Denmark)
Koutroulis, Eftichios; Blaabjerg, Frede
2011-01-01
The DC/AC inverters are the key elements of grid-connected PV energy production systems. In this paper, a new technique for the optimal design of the power section and output filter of a full-bridge, grid-connected PV inverter, is proposed. The objective function which is minimized during...... the Genetic Algorithm-based optimization procedure is the PV inverter Levelized Cost Of the Electricity generated (LCOE). The proposed method has been applied for the optimal design of PV inverters installed at various sites in Europe. The simulation results indicate that the optimal values of the PV inverter...... design variables depend on the PV inverter specifications, the technical and economic characteristics of the components used to build the PV inverter and the meteorological conditions prevailing at the installation area....
A new configuration for multilevel converters with diode clamped topology
DEFF Research Database (Denmark)
Nami, A.; Zare, F.; Ledwich, G.
2008-01-01
of load changes which can avoid neutral point balancing problem in such converters. In addition, the presented topology is suitable for renewable energy systems to boost the low rectified output-voltage. In order to verify the proposed topology, steady state analysis, modelling and simulations are carried......Due to the increased use of renewable energy and power elctronic applications, more multilevel converters (MLC) are developed. A Neutral Point Clamped (NPC) inverter is one of the most used multilevel topologies for wind turbine (WT) and photovoltaic (PV) applications. One of the most crucial...... points in this type of converter is dc-voltage control. In this paper, a novel multi output dc-dc converter connected to a diode clamped topology is presented. This converter, for a given duty cycles, is able to regulate the capacitor voltage to provide an appropriate input voltage for NPC regardless...
Accelerating development of advanced inverters :
Energy Technology Data Exchange (ETDEWEB)
Neely, Jason C.; Gonzalez, Sigifredo; Ropp, Michael; Schutz, Dustin
2013-11-01
The high penetration of utility interconnected photovoltaic (PV) systems is causing heightened concern over the effect that variable renewable generation will have on the electrical power system (EPS). These concerns have initiated the need to amend the utility interconnection standard to allow advanced inverter control functionalities that provide: (1) reactive power control for voltage support, (2) real power control for frequency support and (3) better tolerance of grid disturbances. These capabilities are aimed at minimizing the negative impact distributed PV systems may have on EPS voltage and frequency. Unfortunately, these advanced control functions may interfere with island detection schemes, and further development of advanced inverter functions requires a study of the effect of advanced functions on the efficacy of antiislanding schemes employed in industry. This report summarizes the analytical, simulation and experimental work to study interactions between advanced inverter functions and anti-islanding schemes being employed in distributed PV systems.
Fault Analysis and Detection in Microgrids with High PV Penetration
Energy Technology Data Exchange (ETDEWEB)
El Khatib, Mohamed [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hernandez Alvidrez, Javier [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ellis, Abraham [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-05-01
In this report we focus on analyzing current-controlled PV inverters behaviour under faults in order to develop fault detection schemes for microgrids with high PV penetration. Inverter model suitable for steady state fault studies is presented and the impact of PV inverters on two protection elements is analyzed. The studied protection elements are superimposed quantities based directional element and negative sequence directional element. Additionally, several non-overcurrent fault detection schemes are discussed in this report for microgrids with high PV penetration. A detailed time-domain simulation study is presented to assess the performance of the presented fault detection schemes under different microgrid modes of operation.
Institute of Scientific and Technical Information of China (English)
杜丽媛; 杨富文; 陈建民
2013-01-01
Nowadays model based predictive control is widely used in grid-connected inverter current control, however, modeling accuracy is the key factor that affects its performance. In order to avoid the complex and time consuming modeling process, model free subspace based Linear Quadratic Gaussian (LQG) control strategy is proposed. Input and output measurements are utilized in the subspace predictor design, and then the predictor is used in model free predictive LQG control. This novel approach is applied to the grid-connected photovoltaic (PV) inverter control system. Simulation results show the inverter’s output current could comply with grid standards, which also verify good dynamical performance and strong robustness of the proposed method.%目前模型预测控制广泛地应用于并网逆变器的电流控制中，然而模型不准确是影响预测控制器性能的关键因素。为了避免复杂的建模过程，结合子空间方法和线性二次高斯(Linear Quadratic Gaussian，LQG)控制，提出了基于子空间的LQG控制。利用过去的输入输出数据和未来的输入数据，寻找出未来时刻的输出预测值，从而直接应用到LQG控制器的设计中，并将该方法成功地应用到三相光伏并网逆变器控制中。通过Matlab仿真结果显示逆变器输出电流符合并网标准，证明了该方法的可行性，并且具有良好的动态响应性能和鲁棒性。
Inverter Ground Fault Overvoltage Testing
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chebahtah, Justin [SolarCity Corporation, San Mateo, CA (United States); Wang, Trudie [SolarCity Corporation, San Mateo, CA (United States); McCarty, Michael [SolarCity Corporation, San Mateo, CA (United States)
2015-08-12
This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.
基于LCL滤波器的三电平光伏并网逆变器控制策略%Control Strategy of Grid-connected Three-level PV Inverter with LCL Filter
Institute of Scientific and Technical Information of China (English)
段文燕
2013-01-01
In order to meet the requirement of grid-connected current harmonics with the IEEE Std. 1547 standard, the LCL filter is generally used in the grid-connected PV inverter applications to deeply attenuate high-frequency harmonics. However, the introduction of LCL filters will reduce the stability of system. In order to solve this problem, a novel passive damping control strategy is presented in this paper. Then parallel passive damping and system operation theory are analyzed in detail, and the stability is also studied. In the end, the presented control scheme is simulated by the MATLAB/Simulink. Simulation results show that the instability issue caused by LCL harmonics can be effectively resolved by proposed scheme, which guarantee the grid-connected current harmonics to conform to the IEEE. standards.%为了满足IEEE Std.1547标准对并网电流谐波的要求,光伏并网逆变器输出通常采用LCL滤波器抑制高频谐波.然而,LCL滤波器的引入导致系统稳定性降低.为了解决该问题,本文提出一种电感并联型无源阻尼控制方案.文中详细分析了并联无源阻尼和系统运行工作原理,并进行了稳定性分析.最后在MATLAB/Simulink环境下对控制方案进行验证.仿真结果表明,该方案可有效解决LCL谐振引起的不稳定问题,同时保证并网电流谐波含量满足IEEE标准.
New Multiphase Hybrid Boost Converter with Wide Conversion Ratio for PV System
Directory of Open Access Journals (Sweden)
Ioana-Monica Pop-Calimanu
2014-01-01
Full Text Available A new multiphase hybrid boost converter, with wide conversion ratio as a solution for photovoltaic energy system, is presented in this paper. To ensure that all the phases of the converter operate at the same switching frequency we use interleaving topology. The proposed converter can be used as an interface between the PV system and the DC load/inverter. This multiphase converter has the advantage of reduced value and physical size of the input and output capacitor as well as the effort for the inductors. To validate the operation of the converter we provide the analyses and the simulation results of the converter.
Technologies for converter topologies
Energy Technology Data Exchange (ETDEWEB)
Zhou, Yan; Zhang, Haiyu
2017-02-28
In some embodiments of the disclosed inverter topologies, an inverter may include a full bridge LLC resonant converter, a first boost converter, and a second boost converter. In such embodiments, the first and second boost converters operate in an interleaved manner. In other disclosed embodiments, the inverter may include a half-bridge inverter circuit, a resonant circuit, a capacitor divider circuit, and a transformer.
Thirteen-level inverter for photovoltaic applications
Directory of Open Access Journals (Sweden)
Lasanthika Dissawa
2016-03-01
Full Text Available With the recent cost reduction and efficiency improvement of solar photovoltaic (PV cells, there is a growing interest towards PV systems in different applications. One promising application is solar PV powered electric vehicles. When they are moving on roads, the whole or some parts of the PV system might be shaded by trees, high buildings, etc.; which result in non-uniform insolation conditions. As a remedial measure, this paper presents a development of a cascaded multi-level inverter based PV system for electric vehicle applications. The basic architecture and switching of the converter switches are described. A laboratory prototype of the proposed architecture was implemented using MOSFETs and harmonic performance under different shading conditions was evaluated. It was found, that under shaded conditions, the 3rd harmonic content can increase and that it depends on the number of modules shaded and the loading condition. The shading performance, losses and power utilization of the cascaded multi-level inverter are compared with that of a conventional Pulse Width Modulated (PWM inverter architecture. The proposed inverter shows better immunity for shading than a PWM inverter. Furthermore, it was found that the switching losses of the proposed inverter are one 10th to one 20th of that of a PWM inverter. Additionally, by properly selecting the switches, it is also possible to reduce the conduction losses compared to that of a PWM inverter. Even though the power utilization is compromised at full insolation, the power utilization performance of the proposed inverter is superior under shading conditions, thus ideally suited for the selected application. As the modular nature of the proposed inverter allows cascading of more H-bridges with fewer cells, the harmonic, shading, loss and power utilization performance of the proposed inverter can be enhanced with more number of steps in the output waveform.
DEFF Research Database (Denmark)
Bendsøe, Martin P.; Sigmund, Ole
2007-01-01
Taking as a starting point a design case for a compliant mechanism (a force inverter), the fundamental elements of topology optimization are described. The basis for the developments is a FEM format for this design problem and emphasis is given to the parameterization of design as a raster image...
Fault Ride-Through of a Grid-connected Photovoltaic System with Quasi Z Source Inverter
DEFF Research Database (Denmark)
Al-Durra, Ahmed; Fayyad, Yara; Muyeen, S.M.;
2016-01-01
This article presents fault ride-through schemes for a three-phase quasi Z source single-stage photovoltaic (PV) inverter that is connected to the grid after the distribution network. The quasi Z source inverter employs a unique LC network to couple the inverter main circuit to the input of the PV...
Comparative Study Between Wind and Photovoltaic (PV) Systems
Taha, Wesam
This paper reviews two renewable energy systems; wind and photovoltaic (PV) systems. The common debate between the two of them is to conclude which one is better, in terms of cost and efficiency. Therefore, comparative study, in terms of cost and efficiency, is attempted. Regarding total cost of both, wind and PV systems, many parameters must be taken into consideration such as availability of energy (either wind or solar), operation and maintenance, availability of costumers, political influence, and the components used in building the system. The main components and parameters that play major role in determining the overall efficiency of wind systems are the wind turbine generator (WTG), gearbox and control technologies such as power, and speed control. On the other hand, in grid-connected PV systems (GCPVS), converter architecture along with maximum power point tracking (MPPT) algorithm and inverter topologies are the issues that affects the efficiency significantly. Cost and efficiency analyses of both systems have been carried out based on the statistics available till today and would be useful in the progress of renewable energy penetration throughout the world.
Hawaiian Electric Advanced Inverter Test Plan - Result Summary
Energy Technology Data Exchange (ETDEWEB)
Hoke, Anderson; Nelson, Austin; Prabakar, Kumaraguru; Nagarajan, Adarsh
2016-10-14
This presentation is intended to share the results of lab testing of five PV inverters with the Hawaiian Electric Companies and other stakeholders and interested parties. The tests included baseline testing of advanced inverter grid support functions, as well as distribution circuit-level tests to examine the impact of the PV inverters on simulated distribution feeders using power hardware-in-the-loop (PHIL) techniques. hardware-in-the-loop (PHIL) techniques.
Modified Grid-Connected CSI for Hybrid PV/Wind Power Generation System
Directory of Open Access Journals (Sweden)
D. Amorndechaphon
2012-01-01
Full Text Available The principle of a power conditioning unit for hybrid PV/wind power generation system is proposed. The proposed power conditioner is based on the current source inverter (CSI topology. All energy sources are connected in parallel with a DC-bus through the modified wave-shaping circuits. To achieve the unity power factor at the utility grid, the DC-link current can be controlled via the wave-shaping circuits with the sinusoidal PWM scheme. In this work, the carrier-based PWM scheme is also proposed to minimize the utility current THD. The power rating of the proposed system can be increased by connecting more PV/wind modules through their wave-shaping circuits in parallel with the other modules. The details of the operating principles, the system configurations, and the design considerations are described. The effectiveness of the proposed CSI is demonstrated by simulation results.
Institute of Scientific and Technical Information of China (English)
马献花; 龚仁喜; 李畸勇; 卓浩泽
2012-01-01
Hysteresis control is a control mode of current tracking control; which is widely used in three-phase PV grid-connected inverter system. The main shortcomings are inconstant in the switching frequency and big harmonics of the current. A proposal of a fuzzy hysteresis bandwidth control approach is made for the problems; in which the fuzzy rules are made to regulate the width of the hysteresis dynamically; thus stabilizing the switching frequency by investigating the relationship between switching frequency and hysteresis bandwidth. Modeling and simulation on the MATLAB/Simulink platform show that the method is characterized by small harmonics and high precise in the tracking current and fast response speed contrast to that of the constant bandwidth of hysteresis control; and also maximum switching frequency can be reduced effectively; thus assuring the reliability of the operation of the equipments.%滞环控制是一种应用较为广泛的电流跟踪控制,在三相光伏并网逆变器系统的设计中,控制策略常采用电流滞环控制.这种控制方式存在的主要问题是开关频率不固定、电流谐波较大.针对该问题提出了一种模糊滞环宽度控制的方法.通过研究开关频率和滞环宽度之间的关系,建立模糊规则,动态地调节滞环比较器的宽度,从而达到稳定开关频率的目的.MATLAB建模仿真表明该方法与传统固定滞环环宽的方法相比,具有跟踪电流谐波含量小,跟踪精度高和响应速度快等优点,同时可有效地降低最大开关频率,保证系统装置运行的可靠性.
Institute of Scientific and Technical Information of China (English)
王雪; 张建成
2012-01-01
为实现中小容量单相光伏发电系统灵活、可控运行,弥补现有控制方法在有功功率调度方面存在的灵活性差、误差较大的问题,提出了一种基于输出电流控制的新型双闭环控制策略.首先进行外环控制器的寻优,然后对采用不同调制方式的电流滞环控制与新型双环控制策略进行对比分析.利用Matlab/Simulink软件构建了基于各种方案的并网逆变系统模型并进行仿真分析.结果表明,所提出的控制策略在有功功率调度方面具备显著优势,输出电流总谐波畸变率小,功率可调度范围宽,具有广阔的工程应用前景.%Aiming at realizing the flexible and controllable operation of small and medium-sized capacity single-phase photovoltaic (PV) system and solving the problems of traditional control methods such as inflexibility and error defect, a novel double-loop control strategy based on output current control is proposed. The first step of the research is optimization of outer loop controller. Then, a contrast between hysteresis current control with different modulation modes and the method raised in the paper is made. Grid-connected inverter simulated module is built with Matlab/Simulink software. Simulation results show the proposed control strategy has significant advantages in active power dispatching, namely, the total harmonic distortion rate of output current is smaller, and the active power dispatching range is wider. As a result, this method has a broad engineering application prospect.
Energy Technology Data Exchange (ETDEWEB)
Sahan, Benjamin
2010-11-13
Power electronic converters for adapting the volatile photovoltaic dc generators to the relatively stiff requirements of the distribution and transmission grids are rapidly gaining importance. The inverter technology is principally based on two types of concepts: Voltage Source Inverters and Current Source Inverters. Especially self-commutated Current Source Inverters did not achieve significance until today. This raises the question of the basic criteria which could either prevent the use of those inverters or even promote them. The two basic concepts are first subjected to a systematic comparison. For this purpose dimensionless benchmark factors are used. At the same time different exemplarily setups are described and documented by measurements. A Current Source Inverter system for integration into high-voltage PV modules is presented, which features a single-stage approach and thus achieves a very high efficiency and compact dimensions. Moreover, new types of inverter topology are considered with indirect (controlled) current dc links. Combining low frequency with only a very few high frequency switches opens up new possibilities for power electronics design, e.g. the use of Normally-on SiC-JFETs. This, however, contradicts the common paradigm to only use normally-off switches in power electronics. Apart from this, new approaches for the use of robust and cost efficient thyristor circuits are presented. These are enabled to fulfill the new grid codes even with injected leading reactive power into the electricity grid which contributes to its stability. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Mather, B. A.; Kromer, M. A.; Casey, L.
2013-01-01
With the increasing penetration of distribution connected photovoltaic (PV) systems, more and more PV developers and utilities are interested in easing future PV interconnection concerns by mitigating some of the impacts of PV integration using advanced PV inverter controls and functions. This paper describes the testing of a 500 kW PV inverter using Power Hardware-in-Loop (PHIL) testing techniques. The test setup is described and the results from testing the inverter in advanced functionality modes, not commonly used in currently interconnected PV systems, are presented. PV inverter operation under PHIL evaluation that emulated both the DC PV array connection and the AC distribution level grid connection are shown for constant power factor (PF) and constant reactive power (VAr) control modes. The evaluation of these modes was completed under varying degrees of modeled PV variability.
Institute of Scientific and Technical Information of China (English)
朱晓荣; 刘世鹏; 张海宁; 王东方; 李春来
2016-01-01
不平衡电网电压下，光伏并网逆变器的输出功率和输出电流都将产生波动，给电力系统的稳定运行造成不利影响。根据光伏并网系统的数学模型，提出了光伏并网逆变器基于滑模控制的直接电压/功率控制策略。该控制策略可在电网电压不平衡时有效抑制并网逆变器输出有功功率和无功功率的波动。根据光伏并网逆变器输出功率和正、负序电流的关系，提出了以消除负序电流为控制目标的改进控制策略。此外，为提高系统的运行性能，提出了功率电流协调控制策略。最后，对所提出的控制策略进行了仿真分析，仿真结果验证了所提出控制策略的有效性。%Under unbalanced grid voltage, second order pulsation component will appear in the output power and the output current of the PV grid connected inverter, which will affect the stable operation of the power system. Based on the mathematical model of PV grid connected system, this paper proposes a direct voltage/power control strategy based on sliding mode control (SMC) for the PV grid connected inverter. When the grid voltage is unbalanced, the control strategy can effectively suppress the power oscillation in the active and reactive power. According to the relationship between the output power and the positive/negative sequence current of the PV grid connected inverter, an improved control strategy is proposed to eliminate the negative sequence current. In addition, a power/current coordinated control strategy is proposed to improve the operating performance of the PV system. Finally, simulation analysis is carried out, and the results verify the effectiveness of the proposed control strategy.
Interline Photovoltaic (I-PV) power system - A novel concept of power flow control and management
2011-01-01
This paper presents a new system configuration for a large-scale Photovoltaic (PV) power system with multi-line transmission/distribution networks. A PV power plant is reconfigured in a way that two adjacent power system networks/ feeders can be interconnected. The inverter modules in a PV power plant are configured such that the system is represented as a back to back inverter connected multi-line system, called as Interline-PV (I-PV) system. The proposed I-PV system then can be controlled a...
Lightning protection of PV systems
Pons, Enrico; Tommasini, Riccardo
2013-01-01
Lightning strikes can affect photovoltaic (PV) generators and their installations, involving also the inverter's electronics. It is therefore necessary to evaluate the risk connected to lightning strikes in order to adopt the correct protective measures for the system. The Standard IEC (EN) 62305-2 reports the procedures for the risk calculation and for the choice of proper lightning protection systems. Usually the technical guidelines suggest protecting with SPDs (surge protective devices) b...
Energy Technology Data Exchange (ETDEWEB)
Myrzik, J. [Kassel Univ. (Gesamthochschule) (Germany); Krieger, T.; Zacharias, P. [Institut fuer Solare Energieversorgungstechnik (ISET), Kassel (Germany); Nijs, J.; Mey, B. de [IMEC, Leuven (Belgium); O`Mathuna, S.; Meinhardt, M. [NMRC, Cork (Ireland); Held, E. de; Jantsch, M. [ECN, Petten (Netherlands); Hofkens, H. [SOLTECH, Leuven (Belgium)
1998-12-01
In the context of a project supported by the EU, a miniaturised PV inverter integrated in a module is being developed as a laboratory sample. The main aim of this project is the provision of know-how for the industry. In order to provide aids to decision-making for industrial manufacture, different lines of development are being worked out for this purpose. The systematic listing and judging of different inverter topologies has proved successful in the development of a string inverter. To determine a suitable inverter topology, a systematic procedure is shown in this article, which was carried out with the aid of different circuit calculations. [Deutsch] Im Rahmen eines von der EU gefoerderten Projektes wird ein modulintegrierter, miniaturisierter PV-Wechselrichter als Labormuster entwickelt. Uebergeordnetes Ziel dieses Projektes ist die Bereitstellung von Know-how fuer die Industrie. Hierzu werden verschiedene Entwicklungslinien erarbeitet, um Entscheidungshilfen fuer die industrielle Fertigung bereit zu stellen. Bereits bei der Entwicklung eines Stringwechselrichters hat sich die systematische Aufstellung und Beurteilung verschiedener Wechselrichtertopologien bewaehrt. Zur Ermittlung einer geeigneten Wechselrichtertopologie wird in diesem Beitrag eine systematische Vorgehensweise aufgezeigt, die mit der Hilfe verschiedener Schaltungskalkulationen durchgefuehrt wurde. (orig.)
A Software Tool for Optimal Sizing of PV Systems in Malaysia
Tamer Khatib; Azah Mohamed; K. Sopian
2012-01-01
This paper presents a MATLAB based user friendly software tool called as PV.MY for optimal sizing of photovoltaic (PV) systems. The software has the capabilities of predicting the metrological variables such as solar energy, ambient temperature and wind speed using artificial neural network (ANN), optimizes the PV module/ array tilt angle, optimizes the inverter size and calculate optimal capacities of PV array, battery, wind turbine and diesel generator in hybrid PV systems. The ANN based mo...
Technologies to Increase PV Hosting Capacity in Distribution Feeders: Preprint
Energy Technology Data Exchange (ETDEWEB)
Ding, Fei; Mather, Barry; Gotseff, Peter
2016-08-01
This paper studies the distributed photovoltaic (PV) hosting capacity in distribution feeders by using the stochastic analysis approach. Multiple scenario simulations are conducted to analyze several factors that affect PV hosting capacity, including the existence of voltage regulator, PV location, the power factor of PV inverter and Volt/VAR control. Based on the conclusions obtained from simulation results, three approaches are then proposed to increase distributed PV hosting capacity, which can be formulated as the optimization problem to obtain the optimal solution. All technologies investigated in this paper utilize only existing assets in the feeder and therefore are implementable for a low cost. Additionally, the tool developed for these studies is described.
Remote and Centralized Monitoring of PV Power Plants
DEFF Research Database (Denmark)
Kopacz, Csaba; Spataru, Sergiu; Sera, Dezso
2014-01-01
the inverters within each PV plant. The monitoring software stores the PV measurements in a data warehouse optimized for managing and data mining large amounts of data, from where it can be later visualized, analyzed and exported. By combining PV production measurements data with I-V curve measurements......This paper presents the concept and operating principles of a low-cost and flexible monitoring system for PV plants. Compared to classical solutions which can require dedicated hardware and/or specialized data logging systems, the monitoring system we propose allows parallel monitoring of PV plants...
On Distributed PV Hosting Capacity Estimation, Sensitivity Study, and Improvement
Energy Technology Data Exchange (ETDEWEB)
Ding, Fei; Mather, Barry
2017-07-01
This paper first studies the estimated distributed PV hosting capacities of seventeen utility distribution feeders using the Monte Carlo simulation based stochastic analysis, and then analyzes the sensitivity of PV hosting capacity to both feeder and photovoltaic system characteristics. Furthermore, an active distribution network management approach is proposed to maximize PV hosting capacity by optimally switching capacitors, adjusting voltage regulator taps, managing controllable branch switches and controlling smart PV inverters. The approach is formulated as a mixed-integer nonlinear optimization problem and a genetic algorithm is developed to obtain the solution. Multiple simulation cases are studied and the effectiveness of the proposed approach on increasing PV hosting capacity is demonstrated.
Technologies to Increase PV Hosting Capacity in Distribution Feeders
Energy Technology Data Exchange (ETDEWEB)
Ding, Fei; Mather, Barry; Gotseff, Peter
2016-11-14
This paper studies the distributed photovoltaic (PV) hosting capacity in distribution feeders by using the stochastic analysis approach. Multiple scenario simulations are conducted to analyze several factors that affect PV hosting capacity, including the existence of voltage regulator, PV location, the power factor of PV inverter and Volt/VAR control. Based on the conclusions obtained from simulation results, three approaches are then proposed to increase distributed PV hosting capacity, which can be formulated as the optimization problem to obtain the optimal solution. All technologies investigated in this paper utilize only existing assets in the feeder and therefore are implementable for a low cost. Additionally, the tool developed for these studies is described.
Institute of Scientific and Technical Information of China (English)
冀玉丕; 谢运祥
2012-01-01
归纳与分类了近年提出的多种应用于可再生能源以及光伏发电系统的单相高频链正弦波逆变器拓扑结构,概括与讨论了各种变换器拓扑的优点、缺点,总结了DC/AC逆变器应用于光伏发电系统所面临的技术要求、挑战以及有可能采用的新技术,为研究、开发下一代高性能DC/AC逆变器提供了技术参考.%The paper induced and classified the advantage and disadvantage of various high frequency link sine wave inverter topology generally, which is applied to renewable and photovoltaic generating system recently. In addition, it summarized the technical requirement and challenge and new technology probably applied of DC/AC inverter which is applied in photovoltaic generating system, which provides the technical reference for the research and development of next generation high performance.
Institute of Scientific and Technical Information of China (English)
Manfred W. Gekeler
2013-01-01
The Soft Switching Three Level Inverter (S3L) was first presented in 2011. It represents a novel topology for pulse width modulation (PWM) inverters that are used in electrical drives, in grid supply inverters for photovoltaic and wind power plants and for power supplies. It has a rather simple structure and is thus economically priced. It is completely operated in soft switching mode and consequently only displays very low switching losses. As a result, the efficiency rate is very high and particularly high switching frequency values can be achieved. In the present paper, the functionality is described, prototypes with output power from 20 kVA to 90 kVA are presented and results are specified.% 软开关三电平逆变器(soft switching three-level inverter，S3L)于2011年首次推出。它代表了脉宽调制(pulse width modulation，PWM)逆变器的一种新的拓扑结构，应用于电力驱动，光伏和风力发电厂的并网逆变器，以及用于供电领域。因其结构非常简单，所以价格相当低廉。它完全在软切换模式下运行，并且持续表现出极低的切换损耗。其结果是，效率非常高，而且可以实现特别高的切换频率。该论文对其功能进行描述，还展示一部输出电源为20~90 kVA 的逆变器样品，并对测试结果作详细说明。
PV Derived Data for Predicting Performance; NREL (National Renewable Energy Laboratory)
Energy Technology Data Exchange (ETDEWEB)
Marion, Bill
2015-09-14
A method is described for providing solar irradiance data for modeling PV performance by using measured PV performance data and back-solving for the unknown direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI), which can then be used to model the performance of PV systems of any size, PV array tilt, or PV array azimuth orientation. Ideally situated for using the performance data from PV modules with micro-inverters, the PV module operating current is used to determine the global tilted irradiance (GTI), and a separation model is then used to determine the DNI and DHI from the GTI.
PV Derived Data for Predicting Performance; NREL (National Renewable Energy Laboratory)
Energy Technology Data Exchange (ETDEWEB)
Marion, Bill
2015-09-14
A method is described for providing solar irradiance data for modeling PV performance by using measured PV performance data and back-solving for the unknown direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI), which can then be used to model the performance of PV systems of any size, PV array tilt, or PV array azimuth orientation. Ideally situated for using the performance data from PV modules with micro-inverters, the PV module operating current is used to determine the global tilted irradiance (GTI), and a separation model is then used to determine the DNI and DHI from the GTI.
PV producers must advertise; Werbung wird wichtiger
Energy Technology Data Exchange (ETDEWEB)
Seltmann, T.
2001-01-12
Producers of current inverters are profiting from the growing PV market. The bigger suppliers are enhancing their advertising and marketing efforts while smaller suppliers opt for high-efficiency technology. [German] Vom kraeftigen Wachstum des Photovoltaik-Marktes profitieren zwangslaeufig auch die Wechselrichter-Hersteller. Die groesseren Anbieter verstaerken Vertrieb und Marketing, waehrend die kleineren versuchen, mit besonders effizienter Technik zu glaenzen. (orig.)
DEFF Research Database (Denmark)
Guo, Xiaoqiang; Jia, X.; Lu, Z.;
2016-01-01
Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H...
A review of single-phase grid-connected inverters for photovoltaic modules
DEFF Research Database (Denmark)
Kjaer, Soren Baekhoej; Pedersen, John Kim; Blaabjerg, Frede
2005-01-01
This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single...
Karanayil, Baburaj; Agelidis, Vassilios; Pou Félix, Josep
2014-01-01
In grid-connected photovoltaic (PV) power stations, improving the life expectancy and long-term reliability of three-phase PV inverters is urgently needed to match the significantly higher lifetime of the PV modules. A key contribution toward such improvement is replacing the conventional electrolytic film capacitors by metallized polypropylene film ones. This paper presents a detailed evaluation of a conventional three-phase grid-connected PV inverter performance when replacing the electroly...
Research on Three-phase and Three-level PV's Inverter Based on SVPWM%基于SVPWM的三相三电平光伏并网逆变器的研究
Institute of Scientific and Technical Information of China (English)
张雪; 曹勇; 胡艳美; 邢峰华
2015-01-01
For two-stage grid-connected inverter of photovoltaic system, the controlling method of a three-phase and three-level inverter was introduced based on voltage space vector, so it can achieve a lower switching frequency, weaken the waveform distortion of line current in the AC side, and improve power factor in the AC side. The structure of a three-phase and three-level photovoltaic grid inverter was designed and the system incremental method was used to achieve maximum power tracking; The grid inverter control mode selects SVPWM. In addition, this paper sets up the simulation model through Matlab/Simulink to verify the feasibility system and improve the power quality of grid inverter.%针对两级式光伏发电系统的并网逆变器，提出基于电压空间矢量作为三相三电平逆变器的控制方式，实现了降低开关频率，减弱了交流侧线电流的波形畸变，提高交流侧的功率因数。设计了三相三电平光伏并网逆变器系统的结构，采用导纳增量法实现最大功率跟踪，并网逆变器的控制方式选用 SVPWM ，并通过Matlab/Simulink搭建仿真模型，验证了系统可行性，改善了并网逆变器的电能质量。
Institute of Scientific and Technical Information of China (English)
靳亚丽; 郑恩让; 张晓娟
2012-01-01
针对传统电力系统中SPWM调制的逆变器效率低、可靠性差等缺点,提出了将SVPWM技术应用于光伏并网逆变器中,并在Matlab/Simulink环境下对逆变主电路进行了仿真.同时以TMS320F2812为主控芯片,三相逆变模块为主电路,在SVPWM逆变调制技术的基础上,引入单神经元PI电压闭环控制技术来改善并网逆变器的输出波形,并研制了一台220 V/50 Hz的并网逆变器样机.仿真结果表明,设计方案的可行性和有效性,样机结果表明,该并网逆变器具有硬件电路简单,输出电压谐波畸变率低,电压稳定等优点.%Aiming at the disadvantage of inverter based on traditional SPWM modulation in power system, of which efficiency is not high and the reliability is bad, so SVPWM technology used in photovoltaic grid-connected inverter is proposed and its main circuit is simulated under the environment of Matlab/Simulink. Meanwhile the main control chip is TMS320F2812 and the main circuit is three-phase inverter module, based on SVPWM modulation technology, the single neuron PI voltage closed-loop control method is used to improve the output voltage wave quality of the Grid-connected inverter and a 220 V/50 Hz Grid-connected inverter is developed. According to the simulation results, they prove that the design is feasible and effective. And according to prototype experimental results, the designed Grid-connected Inverter has the advantages of simple hardware circuit, the low output voltage harmonic distortion and voltage stability.
Status and Needs of Power Electronics for Photovoltaic Inverters
Energy Technology Data Exchange (ETDEWEB)
QIN, YU CHIN; MOHAN, NED; WEST, RICK; BONN, RUSSELL H.
2002-06-01
Photovoltaics is the utility connected distributed energy resource (DER) that is in widespread use today. It has one element, the inverter, which is common with all DER sources except rotating generators. The inverter is required to transfer dc energy to ac energy. With all the DER technologies, (solar, wind, fuel cells, and microturbines) the inverter is still an immature product that will result in reliability problems in fielded systems. Today, the PV inverter is a costly and complex component of PV systems that produce ac power. Inverter MTFF (mean time to first failure) is currently unacceptable. Low inverter reliability contributes to unreliable fielded systems and a loss of confidence in renewable technology. The low volume of PV inverters produced restricts the manufacturing to small suppliers without sophisticated research and reliability programs or manufacturing methods. Thus, the present approach to PV inverter supply has low probability of meeting DOE reliability goals. DOE investments in power electronics are intended to address the reliability and cost of power electronics. This report details the progress of power electronics, identifies technologies that are in current use, and explores new approaches that can provide significant improvements in inverter reliability while leading to lower cost. A key element to improved inverter design is the systems approach to design. This approach includes a list of requirements for the product being designed and a preliminary requirements document is a part of this report. Finally, the design will be for a universal inverter that can be applied to several technologies. The objective of a universal inverter is to increase the quantity being manufactured so that mass-manufacturing techniques can be applied. The report includes the requirements and recommended design approaches for a new inverter with a ten-year mean time to first failure (MTFF) and with lower cost. This development will constitute a &apos
Power Control Flexibilities for Grid-Connected Multi-Functional Photovoltaic Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2016-01-01
and intelligent services, such as fault ride-through and reactive power compensation, is the key to attain higher utilisation of solar PV energy. Such functionalities for the future PV inverters can contribute to reduced cost of energy, and thus enable more cost-effective PV installations. To implement...
Monitoring and Fault Detection in Photovoltaic Systems Based On Inverter Measured String I-V Curves
DEFF Research Database (Denmark)
Spataru, Sergiu; Sera, Dezso; Kerekes, Tamas;
2015-01-01
Most photovoltaic (PV) string inverters have the hardware capability to measure at least part of the current-voltage (I-V) characteristic curve of the PV strings connected at the input. However, this intrinsic capability of the inverters is not used, since I-V curve measurement and monitoring......-of-system components through increased series resistance losses, or shunting of the PV modules. To achieve this, we propose and experimentally demonstrate three complementary PV system monitoring methods that make use of the I-V curve measurement capability of a commercial string inverter. The first method is suitable...... for monitoring single or independent PV strings, and is based on evaluating the ratio of certain operation points on the string I-V curve. The second method is applicable to PV systems with identical strings, and is based on monitoring and inter-comparison of string I-V curve parameters. For PV systems with non...
A Software Tool for Optimal Sizing of PV Systems in Malaysia
Directory of Open Access Journals (Sweden)
Tamer Khatib
2012-01-01
Full Text Available This paper presents a MATLAB based user friendly software tool called as PV.MY for optimal sizing of photovoltaic (PV systems. The software has the capabilities of predicting the metrological variables such as solar energy, ambient temperature and wind speed using artificial neural network (ANN, optimizes the PV module/ array tilt angle, optimizes the inverter size and calculate optimal capacities of PV array, battery, wind turbine and diesel generator in hybrid PV systems. The ANN based model for metrological prediction uses four meteorological variables, namely, sun shine ratio, day number and location coordinates. As for PV system sizing, iterative methods are used for determining the optimal sizing of three types of PV systems, which are standalone PV system, hybrid PV/wind system and hybrid PV/diesel generator system. The loss of load probability (LLP technique is used for optimization in which the energy sources capacities are the variables to be optimized considering very low LLP. As for determining the optimal PV panels tilt angle and inverter size, the Liu and Jordan model for solar energy incident on a tilt surface is used in optimizing the monthly tilt angle, while a model for inverter efficiency curve is used in the optimization of inverter size.
Design and comparison of three-level three-phase T-source inverters
DEFF Research Database (Denmark)
Shults, T.; Husev, Oleksandr; Blaabjerg, Frede
2015-01-01
This paper presents guidelines for component design of recently proposed topologies of the three-level three-phase T-source inverters. Two different topologies are considered: T-source inverters with discontinuous input current and T-source inverters with continuous input current. Steady state...
Operating temperatures of open-rack installed photovoltaic inverters
Energy Technology Data Exchange (ETDEWEB)
Zhang, Z.; Wang, L.; Kurtz, S.; Wu, J.; Quan, P.; Sorensen, R.; Liu, S.; Bai, J. B.; Zhu, Z. W.
2016-11-01
This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.
Energy Technology Data Exchange (ETDEWEB)
2014-11-01
This paper explains how advanced inverter functions (sometimes called 'smart inverters') contribute to the integration of high levels of solar PV generation onto the electrical grid and covers the contributions of advanced functions to maintaining grid stability. Policy and regulatory considerations associated with the deployment of advanced inverter functions are also introduced.
Improving Advanced Inverter Control Convergence in Distribution Power Flow
Energy Technology Data Exchange (ETDEWEB)
Nagarajan, Adarsh; Palmintier, Bryan; Ding, Fei; Mather, Barry; Baggu, Murali
2016-11-21
Simulation of modern distribution system powerflow increasingly requires capturing the impact of advanced PV inverter voltage regulation on powerflow. With Volt/var control, the inverter adjusts its reactive power flow as a function of the point of common coupling (PCC) voltage. Similarly, Volt/watt control curtails active power production as a function of PCC voltage. However, with larger systems and higher penetrations of PV, this active/reactive power flow itself can cause significant changes to the PCC voltage potentially introducing oscillations that slow the convergence of system simulations. Improper treatment of these advanced inverter functions could potentially lead to incorrect results. This paper explores a simple approach to speed such convergence by blending in the previous iteration's reactive power estimate to dampen these oscillations. Results with a single large (5MW) PV system and with multiple 500kW advanced inverters show dramatic improvements using this approach.
Cascaded trans-z-source inverters
DEFF Research Database (Denmark)
Li, Ding; Loh, Poh Chiang; Zhu, Miao;
2011-01-01
Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...... the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental...
The Simulation Research on Fuzzy Quasi PR Control of PV Grid Connected Inverter%光伏并网逆变器模糊准 PR 控制仿真研究
Institute of Scientific and Technical Information of China (English)
姚鑫; 罗晓曙; 廖志贤; 李志红
2014-01-01
针对光伏并网逆变器系统的非线性特性，在固定参数 PR 控制方法的基础上，提出了一种模糊准 PR 控制方法。首先介绍单相光伏并网逆变器的结构，并分析准 PR 控制的实现算法、离散化和谐波滤除，然后把模糊控制和准 PR 控制结合应用于并网逆变器同步控制。最后利用 Matlab / simulink 平台进行仿真实验，结果表明：与准 PR 方法相比，所提出的控制方法可使电网电流同步误差更小，适应性和抗干扰性更强，因而具有较好的应用价值。%A fuzzy quasi PR method is proposed for the nonlinear characteristics of photovoltaic grid connected inverter system based on the research on the PR control method with fixed parameters. Firstly,the structure of single - phase photovoltaic grid connected inverter will be introduced. Besides,the working principle of quasi PR control algorithm, the discretization method and the harmonic filtering out will be analyzed in detail. Then,the fuzzy control and quasi PR control will be combined to be applied in grid connected inverter synchronization. At last,by using the Matlab /simulink platform simulation and experimental verification,the simulation experiment results show that the proposed fuzzy quasi PR method can effectively improve the tracking effect compared with the traditional quasi PR method. So this method has a great application value.
Integrating High Penetrations of PV into Southern California: Year 2 Project Update; Preprint
Energy Technology Data Exchange (ETDEWEB)
Mather, B.; Neal, R.
2012-08-01
Southern California Edison (SCE) is well into a five-year project to install a total of 500 MW of distributed photovoltaic (PV) energy within its utility service territory. Typical installations to date are 1-3 MW peak rooftop PV systems that interconnect to medium-voltage urban distribution circuits or larger (5 MW peak) ground-mounted systems that connect to medium-voltage rural distribution circuits. Some of the PV system interconnections have resulted in distribution circuits that have a significant amount of PV generation compared to customer load, resulting in high-penetration PV integration scenarios. The National Renewable Energy Laboratory (NREL) and SCE have assembled a team of distribution modeling, resource assessment, and PV inverter technology experts in order to investigate a few of the high-penetration PV distribution circuits. Currently, the distribution circuits being studied include an urban circuit with a PV penetration of approximately 46% and a rural circuit with a PV penetration of approximately 60%. In both cases, power flow on the circuit reverses direction, compared to traditional circuit operation, during periods of high PV power production and low circuit loading. Research efforts during year two of the five-year project were focused on modeling the distribution system level impacts of high-penetration PV integrations, the development and installation of distribution circuit data acquisition equipment appropriate for quantifying the impacts of high-penetration PV integrations, and investigating high-penetration PV impact mitigation strategies. This paper outlines these research efforts and discusses the following activities in more detail: the development of a quasi-static time-series test feeder for evaluating high-penetration PV integration modeling tools; the advanced inverter functions being investigated for deployment in the project's field demonstration and a power hardware-in-loop test of a 500-kW PV inverter implementing a
Energy Technology Data Exchange (ETDEWEB)
Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)
1994-12-01
This paper reports the study results on development of integrated multifunctional peripheral equipment in fiscal 1994. (1) On development of inverters with no transformer, the following study results were obtained. Converter efficiency reached the target of 95.0% by using an improved general purpose IGBT as switching element of main circuit. Distortion factor of output current harmonics achieved 5% in total current distortion factor, and less than 3% in each order harmonic current one. In control of the DC part of output current, the target less than 0.3% was achieved by inserting a capacitor into detection signal circuit and by detection/correction control of current detector offset. Detection level of 100mA was achieved for DC grounding detection by installing a DC grounding detector in the DC input side of inverters. VCCI 1 level was also achieved for EMI measurement. (2) On development of integrated multifunctional peripheral equipment, evaluation test of the prototype equipment of 0.025m{sup 3} in volume and 17kg in mass was carried out. 3 figs., 1 tab.
Institute of Scientific and Technical Information of China (English)
冯彬; 张广明
2011-01-01
传统光伏并网逆变器多采用二电平逆变器,多电平逆变器受其复杂电路拓扑的制约在光伏系统中应用较少.在传统五电平逆变器拓扑基础上,提出一种简化的H桥五电平单相光伏逆变器.该逆变器采用特定谐波消除法调制控制方案,系统并网电流采用模糊PI自整定控制方法,输出电压和电流具有较低的谐波和du/dt,改善了系统稳定性,提高了系统动态响应过程.构建仿真实验分析验证了控制策略的有效性和可行性.%Traditional grid-connected photovoltaic (PV) inverters are based on two or three-level inverter. Multilevel inverter topology constrained by its complex circuit system is seldom used in PV system. A modified H-bridge five-level singlephase grid-connected inverter on the base of the traditional five-level inverters topology is proposed.The new inverter uses selective harmonic elimination method,and grid-connected current control using the self-adaptive fuzzy PI control method.The output voltage and current have less harmonics and lower du/dt, the control can improve stability of the system and dynamic response of the process. The simulation results verify that the control strategy is valid and feasible.
Trans-Z-source Neutral Point Clamped inverter
DEFF Research Database (Denmark)
Mo, W.; Loh, P. C.; Li, D.;
2012-01-01
Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used...... modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed...... for buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper...
Advanced DC/AC inverters applications in renewable energy
Luo, Fang Lin
2013-01-01
DC/AC inversion technology is of vital importance for industrial applications, including electrical vehicles and renewable energy systems, which require a large number of inverters. In recent years, inversion technology has developed rapidly, with new topologies improving the power factor and increasing power efficiency. Proposing many novel approaches, Advanced DC/AC Inverters: Applications in Renewable Energy describes advanced DC/AC inverters that can be used for renewable energy systems. The book introduces more than 100 topologies of advanced inverters originally developed by the authors,
Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.
2016-07-01
This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules for cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.
Institute of Scientific and Technical Information of China (English)
尹靖元; 金新民; 李金科; 杨捷; 吴学智
2014-01-01
To meet the operational demands on low-cost and high-efficiency for photovoltaic (PV) generation system, a topology of PV grid-connected converter composed of dual inverters connected in series is proposed. A mathematical model for the converter composed of dual inverters connected in series for PV generation system is established and a modulation method, in which the common-mode voltage difference is eliminated, is obtained. Based on the analysis on the active power of two sets of inverters a system control strategy with power equilibrium is put forward to effectively reduce the initial cost of PV generation system and extend the working range of the maximum power point tracking (MPPT) of solar panel. The feasibility of the proposed topology and the effectiveness of the proposed control strategy are validated by both results of simulation and experiments.%为实现光伏发电系统低成本高效率的运行需求，提出了一种双逆变器串联的光伏并网变流器拓扑。通过建立双逆变器串联系统的数学模型，得出了在光伏系统中无共模电压差的调制方法，并基于对2组逆变器有功功率的分析，提出功率均衡的系统控制策略，有效降低光伏系统的初始成本并提升电池板 MPPT 输出电压范围。仿真和实验结果验证了所提拓扑的可行性和控制策略的有效性。
Institute of Scientific and Technical Information of China (English)
王新勇; 许炜; 汪显博; 范波
2011-01-01
提出了一种适用于三相光伏并网逆变器的双滞环电流控制改进算法.根据逆变器线电流与功率器件开关状态的关系,对线电流实行解耦控制,利用双滞环来判断参考空间电压矢量的位置,结合锁相环电路对输出的开关状态进行检测,构成频率闭环控制.最后利用Matlab/Simulink工具箱和3 kW实验平台对双滞环控制算法进行验证.结果表明,该算法保留了传统滞环控制电流跟踪响应快、有限流能力的优点,同时也有效地克服了开关频率变化不固定、开关损耗较大等问题.%An improved algorithm of double hysteresis loop current control method for three-phase PV grid-connected inverter is proposed. The decoupling control of the line current is realized under the relationship between inverter line current and switch status of power instrument The position of reference space voltage vector can be judged by double hysteresis loop. Output switch state can be detected by phase-lockod loop circuit, thus the frequency closed-loop control is constructed. At last, the algorithm is simulated in Matlab/Simulink toolbox and verified on 3 kW experimental platform. The results show that the improved algorithm remains the fast response and limiting current capacity of traditional hysteresis current tracking control, also effectively overcomes the non-fixed switching frequency and the larger switching loss.
Addressing firefighter safety around solar PV systems
Energy Technology Data Exchange (ETDEWEB)
Harris, B. [Sustainable Energy Technologies, Calgary, AB (Canada)
2010-11-15
The article discussed new considerations for installing photovoltaic (PV) systems that address the needs of fire service personnel. The presence of a PV system presents a multitude of dangers for firefighters, including electrical shock, the inhalation of toxic gases from being unable to cut a hole through the roof, falling debris and flying glass, and dead loading on a compromised structure and tripping on conduits. Mapping systems should be modified so that buildings with PV systems are identified for first responders, including firefighters who should learn that solar modules present an electrical hazard during the day but not at night; covering PV modules with foam or salvage covers may not shut the system down to a safe level; it takes a few moments for the power in PV modules to reduce to zero; and PV modules or conduit should never be cut, broke, chopped, or walked upon. The California Department of Forestry and Fire Protection recommends creating pathways and allowing easier access to the roof by setting the modules back from roof edges, creating a structurally sound pathway for firefighters to walk on and space to cut ventilation holes. However, the setback rule makes the economics of solar installation less viable for residential applications. The technological innovations aimed at addressing system safety all focus on limiting firefighter contact with live electrical components to within the extra-low-voltage (ELV) band. Some of the inverters on the market that support ELV system architecture were described. 1 fig.
PV Systems Reliability Final Technical Report.
Energy Technology Data Exchange (ETDEWEB)
Lavrova, Olga [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flicker, Jack David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Armijo, Kenneth Miguel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schindelholz, Eric John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yang, Benjamin Bing-Yeh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-12-01
The continued exponential growth of photovoltaic technologies paves a path to a solar-powered world, but requires continued progress toward low-cost, high-reliability, high-performance photovoltaic (PV) systems. High reliability is an essential element in achieving low-cost solar electricity by reducing operation and maintenance (O&M) costs and extending system lifetime and availability, but these attributes are difficult to verify at the time of installation. Utilities, financiers, homeowners, and planners are demanding this information in order to evaluate their financial risk as a prerequisite to large investments. Reliability research and development (R&D) is needed to build market confidence by improving product reliability and by improving predictions of system availability, O&M cost, and lifetime. This project is focused on understanding, predicting, and improving the reliability of PV systems. The two areas being pursued include PV arc-fault and ground fault issues, and inverter reliability.
Institute of Scientific and Technical Information of China (English)
贺文婷
2015-01-01
This paper discusses the issue related to Inverted Order. There are two forms of Inversion, which are Partial Inversion and Complete Inversion. I analyze three main reasons of Inversion and its usages in details. And what’s more, under what conditions should we use Inverted construction? How can we distinguish the different usages of Complete Inversion and Partial Inversion? In this paper, I will talk more details about Inversion.%本篇论文讨论有关倒装语序的问题。倒装有两种形式，即部分倒装和完全倒装。文中分析了倒装的三个原因及其用法。具体的，在什么情况下需要使用倒装结构？我们如何区分完全倒装和部分倒装的不同用法？本篇论文将作具体阐述。
Multilevel Inverter by Cascading Industrial VSI
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim
2002-01-01
In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...... by a standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations...
Improved PV Control of Grid-Connected Inverter in Low Voltage Micro-Grid%低压微电网逆变器频率电压协调控制
Institute of Scientific and Technical Information of China (English)
孙孝峰; 吕庆秋
2012-01-01
With the increasing acceptance,micro-grid,combined with distributed generation（DG）,may be operated in grid-connected mode or islanding mode.In grid-connected mode,energy management is the main control objectives.While in islanding mode,to maintain voltage and frequency stable is the key point.Taking line impedance into account,PV droop control should be adapted in low voltage system.The PV droop control can share active and reactive power in islanding mode,but it will bring a great offset in voltage and frequency.The article proposes an improved opposite droop control（NPV）： By adding feed-forward control to given power,secondary regulation of the voltage and frequency can be achieved.The NPV managed to do the job of both energy management in grid-connected mode and the secondary regulation of voltage and frequency in islanding mode.The results have been validated through simulations by PSCAD software and experiments.%近年来,分布式发电（Distributed Generation,DG）技术发展迅猛,DG结合本地负载、储能设备等可构成微电网,微电网能够在并网模式与孤岛模式下运行。并网时,DG输出给定的功率,实现能量管理;孤岛运行时,要求DG维持微电网电压和频率稳定。因而微网中逆变器的控制尤为重要。由于传输线阻抗特性不同,本文在低压系统中应采用PV下垂控制,PV下垂控制能够实现孤岛运行时不同DG均分负载,但它是有差调节,电压和频率会存在较大的偏差。本文提出一种改进的PV下垂控制（NPV）：加入电压和频率偏差的前馈调节,可实现电压和频率的二次调节。以微电网脱网运行的稳态以及暂态情况分析为例,通过PSCAD仿真以及实验,验证了NPV不但可以实现并网时的能量管理而且还实现了孤岛运行过程中电压和频率的二次调节。
Design of 6 switched 3-level inverter with RL load
Directory of Open Access Journals (Sweden)
Ali Saygın
2016-10-01
Full Text Available In this study, an alternative topology to multilevel inverter topologies is given. 6 IGBT seminconductor switches are used in this topology and coupled inductors are used in the output stage of the inverter. Using coupled inductors voltages, the 6 switched 3-level inverter has been obtained. In the simulation study, Proportional Integral (PI controller has been used. By using the data taken from controller, the required switching signals have been produced for a 6 switched 3-level inverter. These signals have been taken by using space vector pulse width modulation technique. Using Computer Aided Design (CAD analysis a RL load that have 10 Ω and 0.2 H values is simulated and inverter performance has been investigated.
Study on inverter fault-tolerant operation of PMSM DTC
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper presents an investigation of inverter fault-tolerant operation for a permanent magnet synchronous motor (PMSM) direct torque control (DTC) system under various inverter faults. The performance of a faulty standard 6-switch inverter driven PMSM DTC system is analyzed. To avoid the loss or even disaster caused by the inverter faults, a topology-modified inverter with fault-tolerant capability is introduced, which is reconfigured as a 3-phase 4-switch inverter. The modeling of the 4-switch inverter is then analyzed and a novel DTC strategy with a unique nonlinear perpendicular flux observer and feedback compensation scheme is proposed for obtaining a continuous, disturbance-free drive system. The simulation and experimental results demonstrate that the proposed inverter fault-tolerant PMSM DTC system is able to operate stably and continuously with acceptable static and pretty good dynamic performance.
Indian Academy of Sciences (India)
M Vijayakumar; S Vijayan
2014-08-01
This paper proposes a Photovoltaic (PV)-based three-phase four-wire Series Hybrid Active Power Filter (SHAPF), it comprises of a Series Active Power Filter (SAPF) and an LC shunt passive filter. The proposed system eliminates both the current and voltage harmonics and compensates reactive power, neutral current and voltage interruption. A SAPF demands a source of energy for compensating the voltage sag/swell. This system found a new topology for SHAPF which utilizes the PV with DC–DC boost converter as a source of DC power for the series active filter. The compensation current reference evaluation is based on the twin formulation of the vectorial theory of electrical power theorem with Fuzzy Logic Controller (FLC). The PV array/battery managed DC–DC boost converter is employed to step up the voltage to meet the DC bus voltage requirement of the three-leg Voltage Source Inverter (VSI). The foremost benefit of the proposed system is that, it will provide uninterrupted compensation for the whole day. This system utilizes the renewable energy; accordingly saves the energy and provides the uninterruptable power supply to critical/sensitive load, through the PV array/battery bank during both day time and night time. An experimental model was established and results were obtained, which indicated the capability of the proposed control scheme.
2011-01-01
This paper proposes multi-level PV system; three PV generators each coupled to a buck cell. Each PV-generator-buckconverter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal/abnormal conditions is investigated by thoroughly mathematical and simulation work. Peer Reviewed
6 5KVA POWER INVERTER DESIGN AND SIMULATION BASED ...
African Journals Online (AJOL)
DR. AMINU
Five (5) kVA power inverter was designed and simulated base on two topologies; Boost ... stages were plotted and the results show a significant increase in the voltage and duty cycle. ... also provides the industries with effective methods to.
Compensation techniques for non-linearities in H-bridge inverters
Directory of Open Access Journals (Sweden)
Daniel Zammit
2016-12-01
Full Text Available This paper presents compensation techniques for component non-linearities in H-bridge inverters as those used in grid-connected photovoltaic (PV inverters. Novel compensation techniques depending on the switching device current were formulated to compensate for the non-linearities in inverter circuits caused by the voltage drops on the switching devices. Both simulation and experimental results will be presented. Testing was carried out on a PV inverter which was designed and constructed for this research. Very satisfactory results were obtained from all the compensation techniques presented, however the exact compensation method was the most effective, providing the highest reduction in harmonics.
A Novel Frequency Restoring Strategy of Hydro-PV Hybrid Microgrid
DEFF Research Database (Denmark)
Wei, Feng; Kai, Sun; Guan, Yajuan
2014-01-01
The conventional PV systems based on the voltage inverters only inject dispatched power to the utility grid when they work at a grid-connected mode in the hydro-PV hybrid microgrid. Due to the droop method employed for load sharing between generators, as well as the enormous inertia of system....... The existence of frequency steady-state error and the slow active power/frequency dynamic response are inevitable. Therefore, a novel frequency restoring strategy for the hydro-PV hybrid microgrid based on the improved hierarchical control of PV systems is proposed in this paper. The output active power of PV...
Monitoring and Analysis of Two Grid Connected PV Systems
2013-01-01
International audience; In this paper, two grid connected photovoltaic systems are studied and monitored for fault detection ad predictive reliability. The first PV grid, is at CNRS-PROMES laboratory in Perpignan, built in 2001 with 3 PV arrays named "Shed","Brise soleil","Mur rideau") connected to the grid thanks to many inverter of different power (3 of 4KWC and 2 of 2.5KWC). The second one is at CNRS-LAAS in Toulouse with a power of 100kWc. It is composed of a facade of 36kWc PV array and ...
DEFF Research Database (Denmark)
Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
-in operation, especially at night. This serves as a motivation for utilizing the PV inverters at night for reactive power compensation. Thus, a detailed analysis on the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance and also the reliability is performed...... for different values of reactive power injection an assessment of the economic impacts is made. This analysis can be useful in choosing between conventional reactive power devices or PV inverters for injecting reactive power to the grid.......Current energy paradigm of mixed renewables seems to urgently require reactive power provision at various feed-in points of the utility grid. Photovoltaic (PV) inverters are able to provide reactive power in a decentralized manner at the grid-connection point even outside active power feed...
PV system field experience and reliability
Durand, Steven; Rosenthal, Andrew; Thomas, Mike
1997-02-01
Hybrid power systems consisting of battery inverters coupled with diesel, propane, or gasoline engine-driven electrical generators, and photovoltaic arrays are being used in many remote locations. The potential cost advantages of hybrid systems over simple engine-driven generator systems are causing hybrid systems to be considered for numerous applications including single-family residential, communications, and village power. This paper discusses the various design constraints of such systems and presents one technique for reducing hybrid system losses. The Southwest Technology Development Institute under contract to the National Renewable Energy Laboratory and Sandia National Laboratories has been installing data acquisition systems (DAS) on a number of small and large hybrid PV systems. These systems range from small residential systems (1 kW PV - 7 kW generator), to medium sized systems (10 kW PV - 20 kW generator), to larger systems (100 kW PV - 200 kW generator). Even larger systems are being installed with hundreds of kilowatts of PV modules, multiple wind machines, and larger diesel generators.
Evaluation of the Voltage Support Strategies for the Low Voltage Grid Connected PV
DEFF Research Database (Denmark)
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2010-01-01
PVs. In order to increase PV penetration level further, new voltage support control functions for individual inverters are required. This paper investigates distributed reactive power regulation and active power curtailment strategies regarding the development of PV connection capacity by evaluation......Admissible range of grid voltage is one of the strictest constraints for the penetration of distributed photovoltaic (PV) generators especially connection to low voltage (LV) public networks. Voltage limits are usually fulfilled either by network reinforcements or limiting of power injections from...
Power Electronic System for Multi-MW PV sites
DEFF Research Database (Denmark)
Paasch, Kasper
for solar inverters is under a severe pressure regarding cost reduction. The main topic of this thesis is the investigation of the potential advantage of applying string inverters with multiple Maximum-Power-Point-trackers (MPPT) in large PV plants compared to the use of one large central inverter with one.......4%. A portable IV-scanning instrument for the fast long term characterization of solar panels was developed as part of the project. Each second a sweep of the IV-characteristics of a solar panel is performed and the result stored for later analysis. The instrument is based on an active load, is optimized...
Design and Control of an Inverter for Photovoltaic Applications
DEFF Research Database (Denmark)
Kjær, Søren Bækhøj
. The electrical infrastructure around the world is based on AC voltage, with a few exceptions, with a voltage of 120 Volt or 230 Volt in the distribution grid. PV modules can therefore not be connected directly to the grid, but must be connected through an inverter. The two main tasks for the inverter are to load...... (app. 4.0 € per Watt), or about 5000 DKK (app. 670 € per system) for a standard PV module and inverter with a nominal power of 160 Watt. This corresponds to a production-price of 0.24 € per kWh over a time period of 25 years, which cannot yet compete with other energy sources. However, it might...... and cheap concepts for converting electrical energy, from the PV module to the grid. Research has therefore been done in the field of inverter technologies, which is used to interface a single PV module to the grid. The inverter is developed with focus on low cost, high reliability and mass...
Impedance estimation of photovoltaic modules for inverter start-up analysis
Indian Academy of Sciences (India)
PALLAVI BHARADWAJ; ABHIJIT KULKARNI; VINOD JOHN
2017-08-01
Starting-up of photovoltaic (PV) inverters involves pre-charging of the input dc bus capacitance. Ideally, direct pre-charging of this capacitance from the PV modules is possible as the PV modules are current limited. Practically, the parasitic elements of the system such as the PV module capacitance, effective wire inductance and resistance determine the start-up transient. The start-up transient is also affected by the contactor connecting the PV modules to the inverter input dc bus. In this work, the start-up current and voltages are measured experimentally for different parallel and series connections of the PV modules. These measurements are used to estimate the stray elements, namely the PV module capacitance, effective inductance and resistance.The estimation is based on a linear small-signal model of the start-up conditions. The effect of different connections of the PV modules and the effect of varying irradiation on the scaling of the values of the stray elements are quantified. The System model is further refined by inclusion of connecting cable capacitance and contactor resistance. Dynamics of the resulting fifth-order model are seen to be consistent with those of the simplified third-order model. The analysis of this paper can be used to estimate the expected peak inrush current in PV inverters. It can also be used to arrive at a detailed modelling of PV modules to evaluate the transient behaviour.
Fire resistant PV shingle assembly
Lenox, Carl J.
2012-10-02
A fire resistant PV shingle assembly includes a PV assembly, including PV body, a fire shield and a connection member connecting the fire shield below the PV body, and a support and inter-engagement assembly. The support and inter-engagement assembly is mounted to the PV assembly and comprises a vertical support element, supporting the PV assembly above a support surface, an upper interlock element, positioned towards the upper PV edge, and a lower interlock element, positioned towards the lower PV edge. The upper interlock element of one PV shingle assembly is inter-engageable with the lower interlock element of an adjacent PV shingle assembly. In some embodiments the PV shingle assembly may comprise a ventilation path below the PV body. The PV body may be slidably mounted to the connection member to facilitate removal of the PV body.
Inverter Anti-Islanding with Advanced Grid Support in Single- and Multi-Inverter Islands
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy
2016-08-16
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1. In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2. The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness.
Effect of Ambient Temperature on Performance of Grid-Connected Inverter Installed in Thailand
Directory of Open Access Journals (Sweden)
Kamonpan Chumpolrat
2014-01-01
Full Text Available The effects of temperature on performance of a grid-connected inverter, and also on a photovoltaic (PV system installed in Thailand have been investigated. It was found that the maximum efficiency of the inverter showed 2.5% drop when ambient temperature was above 37°C. The inverter performed efficiently in November and December, the months of high irradiance, and monthly average ambient temperature of lower than 35°C, allowing relatively high system performance ratio in this period. Our results show that high temperature provides negative impacts not only on the PV modules, but also on the performance of the inverter. Thus, the effect of temperature on the inverter efficiency should be taken into account when predicting energy yield or analyzing losses of the PV systems—especially in high temperature regions.
Advanced Modular Inverter Technology Development
Energy Technology Data Exchange (ETDEWEB)
Adam Szczepanek
2006-02-04
Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high quality AC output that energy system customers demand. Today's inverters are expensive due to the cost of the power electronics components, and system designers must also tailor the inverter for individual applications. Thus, the benefits of mass production are not available, resulting in high initial procurement costs as well as high inverter maintenance and repair costs. Electricore, Inc. (www.electricore.org) a public good 501 (c) (3) not-for-profit advanced technology development consortium assembled a highly qualified team consisting of AeroVironment Inc. (www.aerovironment.com) and Delphi Automotive Systems LLC (Delphi), (www.delphi.com), as equal tiered technical leads, to develop an advanced, modular construction, inverter packaging technology that will offer a 30% cost reduction over conventional designs adding to the development of energy conversion technologies for crosscutting applications in the building, industry, transportation, and utility sectors. The proposed inverter allows for a reduction of weight and size of power electronics in the above-mentioned sectors and is scalable over the range of 15 to 500kW. The main objective of this program was to optimize existing AeroVironment inverter technology to improve power density, reliability and producibility as well as develop new topology to reduce line filter size. The newly developed inverter design will be used in automotive and distribution generation applications. In the first part of this program the high-density power stages were redesigned, optimized and fabricated. One of the main
Institute of Scientific and Technical Information of China (English)
吴学智; 尹靖元; 杨捷; 童亦斌
2013-01-01
提出了一种采用双级无隔离变压器的新型单相光伏并网逆变器拓扑，由于光伏池板与电网零线直接相连，可消除光伏池板对地的共模电压，解决了共模漏电流问题。所提拓扑采用了高频倍压的方式实现升压变换器与并网逆变器的连接，避免了三电平并网逆变器存在的中点电位二次脉动问题，降低了直流侧滤波电容的容量需求。为实现对单相并网电流的无误差控制，并网控制中采用比例谐振控制器，增加了系统的稳定性和提高了并网电流质量。仿真与实验结果均表明所提光伏并网逆变器拓扑的可行性。%The topology of a novel single-phase two-stage grid-connected Photovoltaic (PV) inverter without isolation transformer is proposed. The direct connection of PV panels with the zero line of power grid can eliminate the common mode voltage of PV panel to the ground, so the problem of common mode leakage current is solved. In the proposed topology the high-frequency voltage-doubling mode is utilized for the connection of boost converter with grid-connected inverter to avoid the secondary pulsation of neutral point potential existing in three-level grid-connected inverter, thus the demand on the capacity of filter capacitor at DC side is reduced. To implement the astatic control of single-phase grid-connected current, the proportional-resonant (PR) controller is adopted in the grid-connection control to enhance the stability of control system and improve the quality of grid-connected current. Results of simulation and experiments show that the topology of the proposed grid-connected PV inverter is feasible.
Directory of Open Access Journals (Sweden)
Samir HADJERI
2017-06-01
Full Text Available This paper proposes an autonomous photovoltaic (PV pumping system for rural/remote applications especially in the large desert in northern Africa where the sun radiation is abundant. Since PV generators exhibit nonlinear I-V characteristics and their maximum power point varies with solar radiation. For this reason, the MPPT controller is used to optimize the solar energy conversion by guaranteeing fast maximum power point tracking (MPPT. This feature has an essential role in dynamic response and efficiency of the photovoltaic system, thus it maximizes the amount of extracted natural gas to be conveyed to another site for an ulterior utilization. Here a robust maximum power point tracker (MPPT using incremental conductance algorithm is applied to the duty cycle value of the DC-DC converter which acts directly on the drive speed. A DC/DC boost is used to enhance voltage up to the favourite level and the SVPWM inverter connects it to a powerful induction motor for a pumping of natural gas application, these systems are at the heart of many industrial sectors such as the oil industry, the production of thermal and nuclear energy etc. An understanding of how these systems operate is essential to increase their performance and reduce their operating costs. Furthermore, three phase voltage-fed PWM inverters are recently showing growing popularity for multi-megawatt industrial drive applications, the main purpose of these topologies is to provide a three-phase voltage source, where the amplitude, phase, and frequency of the voltages should always be controllable. The model of a three-phase voltage source inverter is modelled and discussed based on space vector modulation theory. Simulation results are obtained using MATLAB/Simulink environment for effectiveness of the proposed system.
Design of New Single-phase Multilevel Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2014-07-01
Full Text Available Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multilevel inverter and conventional cascade topology. The proposed topology is analyzed by the experimental and simulation results.
Directory of Open Access Journals (Sweden)
Aliaa N.Madkor
2015-08-01
Full Text Available Abstract The DCAC inverters are used in grid-connected PV energy production systems as the power processing interface between the PV energy source and the electric grid. The energy injected into the electric grid by the PV installation depends on the amount of power extracted from the PV power source and the efficient processing of this power by the DCAC inverter. The main target of this paper is to determine the principle that achieves high reliability and efficiency with the low cost of the photovoltaic grid-connected system. Accordingly we are considering the inverter as it represents the important part of the system by a comparison among the following three systems The system has one inverter with the power of 100 kw The system has two inverters each has the power of 50 kw and The system has twenty inverters each has the power of 5 kW. We will check the effect of number of inverters in photovoltaic grid-connected system on efficiency reliability and cost taking into account the fixed system one axis tracking system and two axes tracking system. Also in order to validate the accuracy of the proposed control strategy grid-connected PV system is simulated based on MATLABSimulink.
Energy Technology Data Exchange (ETDEWEB)
Candido, Diogo Brum
2010-07-01
This master thesis analyses and implements a stand-alone photovoltaic system based on decentralized 'Multi String' topology. The proposed system is composed of a set of DC-DC converters linked to the PV arrays of panels, a bidirectional converter to perform the control of the charge/discharge process of the battery bank and ensure the specifications of DC link and a full-bridge inverter that feed the AC loads. Therefore, all operation modes that the stand-alone PV system can work are presented and analyzed. As the chief aim is to ensure the energy balance of the stand-alone PV system, are presented independents control loops for each converter of the PV system and a propose of a supervisory control that, based on information about the conditions of the DC link and the bank of batteries, defines each operation mode should be active, in order to maximize the power extracted from the PV arrays, the life cycle of the battery bank and ensuring the uninterrupted feeding of energy to the loads. Finally, simulation and experimental results validate the operation of the proposed system under different load and solar radiation conditions. (author)
Energy Technology Data Exchange (ETDEWEB)
Baltus, C.W.A.; Wiggelinkhuizen, E.J.
1998-01-01
In this first progress report of the analytical monitoring of the title system the results of the measurements in the period 5 September 1997 - 1 December 1997 are presented. During the measuring period the photovoltaic (PV) system did not break down. The nominal capacity of the 44 PV-modules is 2090 Wp. The inverter capacity is 1500 W, which is underdimensioned. In case of high solar radiation the generated capacities do not correlate with the intensity of the solar radiation because of the limited inverter capacity. The annual energy yield is 2.1% lower compared to a non-underdimensioned inverter. The performance ratio is circa 0.81. The average efficiency of the inverter is 89%, the low radiation losses are 5.1%. The problem of the measurement of the inverter efficiency in case of high solar radiation has not yet been solved. 1 ref.
Dual-topology insertion of a dual-topology membrane protein.
Woodall, Nicholas B; Yin, Ying; Bowie, James U
2015-01-01
Some membrane transporters are dual-topology dimers in which the subunits have inverted transmembrane topology. How a cell manages to generate equal populations of two opposite topologies from the same polypeptide chain remains unclear. For the dual-topology transporter EmrE, the evidence to date remains consistent with two extreme models. A post-translational model posits that topology remains malleable after synthesis and becomes fixed once the dimer forms. A second, co-translational model, posits that the protein inserts in both topologies in equal proportions. Here we show that while there is at least some limited topological malleability, the co-translational model likely dominates under normal circumstances.
Physical Effects of Distributed PV Generation on California's Distribution System
Cohen, Michael A
2015-01-01
Deployment of high-penetration photovoltaic (PV) power is expected to have a range of effects -- both positive and negative -- on the distribution grid. The magnitude of these effects may vary greatly depending upon feeder topology, climate, PV penetration level, and other factors. In this paper we present a simulation study of eight representative distribution feeders in three California climates at PV penetration levels up to 100\\%, supported by a unique database of distributed PV generation data that enables us to capture the impact of PV variability on feeder voltage and voltage regulating equipment. When comparing the influence of feeder location (i.e. climate) versus feeder type on outcomes, we find that location more strongly influences the incidence of reverse power flow, reductions in peak loading and the presence of voltage excursions. On the other hand, we find that feeder characteristics more strongly influence the magnitude of loss reduction and changes in voltage regulator operations. We find th...
级联式逆变器在光伏并网系统的应用研究%Application of cascaded inverter in photovoltaic grid-connected system
Institute of Scientific and Technical Information of China (English)
张洋; 王君艳
2013-01-01
The circuit topology architecture of the cascading multi⁃level inverter was adopted in the photovoltaic(PV)grid⁃connected system. The control strategy of the PV grid⁃connected system based on the architecture is studied in this paper. In or⁃der to realize effective grid⁃connecting and get the same phase between current and grid voltage,the hybrid control mode with staircase control and current loop control was applied on the basis of the control strategies of single⁃stage PV grid⁃connected sys⁃tem and the cascaded inverter. Matlab/Simulink simulation analysis of the PV grid⁃connected system was conducted to verify the feasibility of the control method. The application of current loop control using PR regulator improved the efficiency of the casca⁃ded inverter.% 采用级联式多电平逆变器的电路拓扑结构，并对基于此结构的光伏并网系统的控制策略进行研究。为实现有效并网，使得并网电流与电网电压相位一致，在结合单级光伏并网系统控制策略和级联式逆变器控制策略两者特点的基础上，采用阶梯波控制与电流环控制的混合控制方式，并对此系统进行Matlab/Simulink仿真分析，验证这种控制方法的可行性。采用PR调节器的电流环控制，提高了级联式逆变器的效率。
A new Zero Voltage Switching three-level NPC inverter
DEFF Research Database (Denmark)
He, Ning; Chen, Yenan; Xu, Dehong
2015-01-01
A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...... switches in the proposed inverter, which include both the main switches and the auxiliary switches. The design of resonant circuits parameters is also provided. Finally the proposed circuit and ZVS SVM scheme are verified by experimental results and demonstrate a superior performance....
Directory of Open Access Journals (Sweden)
SRDIC, S.
2015-08-01
Full Text Available This paper presents a buck-boost converter which is modified to utilize new 600 V gallium nitride (GaN power semiconductor devices in an application requiring 1200 V devices. The presented buck-boost converter is used as a part of a dc/dc stage in an all-GaN photovoltaic (PV inverter and it provides a negative voltage for the 3-level neutral-point-clamped (NPC PWM inverter which is connected to the utility grid. Since in this application the transistor and the diode of the buck-boost converter need to block the sum of the PV string voltage (which is normally in the range from 150 to 350 V and the dc bus voltage (which is in the order of 400 V, the 1200 V devices or series connection of 600 V devices need to be employed. Currently, 1200 V GaN power semiconductor devices are not commercially available. Therefore, the standard buck-boost converter is modified to enable the use of 600 V GaN devices in this particular application. Based on the proposed converter topology, a PSpice simulation model and a 600 W converter prototype were developed. Both simulation and experimental results show successful operation of the converter.
Single-Phase Single-Stage PV-Grid System Using VSI Based on Simple Control Circuit
Directory of Open Access Journals (Sweden)
Slamet Riyadi
2012-12-01
Full Text Available Integrating electric energy generated by PV with utilities has been developed. Some of these using two-stage converters and the others using single stage converters. For systems with two-stage converters, the first stage converter acts as a MPPT to maximize power generated by PV and the second stage is used as an interface to the utilities. In the single-stage system, an inverter is used for both function. In this paper, PV-Grid System using a single-stage Voltage Source Inverter is proposed. The simple control circuit to make PV generate maximum power and keeping power equilibrium between PV and inverter output power is used. To verify the analysis, simulations are done.
Energy Technology Data Exchange (ETDEWEB)
Van der Borg, N.J.C.M.; Jansen, M.J. [ECN Zon en Wind, Petten (Netherlands)
2000-01-01
Under contract from a Dutch energy distribution company (NUON), ECN is carrying out a monitoring program for a number of PV systems that are installed on houses in the urban area 'Het Woudhuis' in Apeldoorn, Netherlands. It concerns four groups of houses with PV systems which differ from each other in type of PV system or the orientation of the roofs. This document is a report of the technical monitoring concerning one group, comprising of 14 PV systems, during the period from 5 September 1997 to 4 September 1999. The average yield of the PV systems, standardized for a climatological average year for the Netherlands, is 706 kWh/kW{sub p}. An expanded monitoring program was carried out for one of the systems, which has led to detailed information about the incoming radiation, the behaviour of the PV panels and the inverter. 4 refs.
Developing High PV Penetration Cases for Frequency Response Study of U.S. Western Interconnection
Energy Technology Data Exchange (ETDEWEB)
Tan, Jin; Zhang, Yingchen; Veda, Santosh; Elgindy, Tarek; Liu, Yilu
2017-05-11
Recent large penetrations of solar photovoltaic (PV) generation and the inertial characteristics of inverter-based generation technologies have caught the attention of those in the electric power industry in the United States. This paper presents a systematic approach to developing test cases of high penetrations of PV for the Western Interconnection. First, to examine the accuracy of the base case model, the Western Electricity Coordinating Council (WECC) model is validated by using measurement data from synchronized phasor measurement units. Based on the 2022 Light Spring case, we developed four high PV penetration cases for the WECC system that are of interest to the industry: 5% PV+15 % wind, 25% PV+15% wind, 45% PV+15% wind, 65% PV+15% wind). Additionally, a method to project PV is proposed that is based on collected, realistic PV distribution information, including the current and future PV power plant locations and penetrations in the WECC system. Both the utility-scale PV plant and residential rooftop PV are included in this study.
Energy Technology Data Exchange (ETDEWEB)
Tan, Jin; Zhang, Yingchen; Veda, Santosh; Elgindy, Tarek; Liu, Yilu
2017-04-11
Recent large penetrations of solar photovoltaic (PV) generation and the inertial characteristics of inverter-based generation technologies have caught the attention of those in the electric power industry in the United States. This paper presents a systematic approach to developing test cases of high penetrations of PV for the Western Interconnection. First, to examine the accuracy of the base case model, the Western Electricity Coordinating Council (WECC) model is validated by using measurement data from synchronized phasor measurement units. Based on the 2022 Light Spring case, we developed four high PV penetration cases for the WECC system that are of interest to the industry: 5% PV+15 % wind, 25% PV+15% wind, 45% PV+15% wind, 65% PV+15% wind). Additionally, a method to project PV is proposed that is based on collected, realistic PV distribution information, including the current and future PV power plant locations and penetrations in the WECC system. Both the utility-scale PV plant and residential rooftop PV are included in this study.
Analysis and Simulation of a High Performance Quasi Resonant PWM Inverter for Solar Power Generation
Institute of Scientific and Technical Information of China (English)
Yun-Parn Lee; Yu-Huang Lin; Yu-Lun Lin
2016-01-01
A quasi resonant pulse width modulation (PWM) inverter is used in a solar power system to convert the solar panel and battery charger’s direct current (DC) output to alternating current (AC). Although much has been published about DC to AC PWM inverters, none of the previous work has shown modeling and simulation results for DC to AC inverters. In this study, we suggest a new topology for a quasi resonant PWM inverter. Experimental results are also presented.
Analysis and Design of Solar Photo voltaic Grid Connected Inverter
Directory of Open Access Journals (Sweden)
Muddasani Satyanarayana
2015-08-01
Full Text Available This paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications, however traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid but losses will increase in the network leading to reduced efficiency of the system. In order to increase the efficiency, with reduced size and cost of the system, the effective solution is to remove the isolation transformer. But common mode (CM ground leakage current due to parasitic capacitance between the PV panels and the ground making the system unreliable. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV systm two control algorithms of multi-carrier pwm are implemented and compared for performance analysis.The shoot-through issue that is encountered by traditional voltage source inverter is analyzed for enhanced system reliability. These control algorithms are compared for common mode voltage and THD comparisons. The proposed system is designed using MATLAB/SIMULINK software for analysis.
2014-01-01
The two basic topologies of switch mode DC-DC converters (Buck and Boost) are analyzed with a view of their use in PV (photovoltaic) systems, as the photovoltaic generator exhibits non-linear characteristics due to the change in environmental condition and load variation. As the efficiency of PV panels is low it becomes mandatory to extract maximum power from the PV panel at a given period of time. Several MPPT algorithms with different types of converters are being proposed f...
Institute of Scientific and Technical Information of China (English)
杨秋霞; 李坤; 王虎; 赵翠妹
2016-01-01
传统的比例积分(PI)控制由于具有一定的稳态误差，无法实现对并网电流快速精确的控制，光伏系统并网以后所引入的电网电感对 LCL 滤波器的阻尼策略也有着不可忽略的影响。为了解决上述问题，提出了一种 PDFI控制下单相光伏并网逆变器的混合阻尼控制策略。该策略介绍了比例延时反馈积分(PDFI)控制，在原有的 PI 控制上加上简单反馈电路，实现了并网电流的无稳态误差控制。同时分析了以阻尼系数为研究对象的混合阻尼控制，改善了电网电感对 LCL 滤波器的阻尼影响。理论分析、实例仿真的结果表明，该控制策略下，系统能够稳定运行，并网电流实现了精确控制，并且对电网电感具有良好的适应性。%The conventional proportional-integral (PI) control can not achieve the rapid and precise control of the grid-connected current because of its steady-state error. The introduction of grid inductor also has a non-negligible impact to damping strategy of the LCL filter when the PV system connects into the grid. To overcome the problems mentioned above, this paper presents a hybrid damping control strategy for single-phase grid-connected PV inverter with the control of PDFI. This strategy introduces proportional delay feedback integral (PDFI) control which adds a simple feedback circuit to the original PI control and can achieve the control of the grid current without steady-state error. The hybrid damping control is also analyzed which takes damping coefficient as the research object, and the impact of the grid inductor to damping strategy of the LCL filter is improved with addition of the hybrid damping control. The results of the theoretical analysis and the simulation both show that the proposed strategy has a great contribution to the control of the grid current and the steady operation of the system, and also has a good adaptability to the grid inductor.
Practical Results of a Five-level Flying Capacitor Inverter
Directory of Open Access Journals (Sweden)
O. Sivkov
2010-01-01
Full Text Available This paper investigates the realization of a five-level Flying Capacitor Inverter. After a brief description of general Power Electronic Converters and an introduction to the advantages of Multilevel Inverters over conventional two-level Inverters the main focus is on the five-level Flying Capacitor Inverter. The Flying Capacitor Multilevel Inverter (FCMI is a Multilevel Inverter (MI where the capacitor voltage can be balanced using only a control strategy for any number of levels. After a general description of five-level FCMI topology, the simulation and experimental results are presented. The capacitor voltage is stabilized here with various output voltage amplitude values. The simulation and experimental results of five-level FCMI show that the voltage is stabilized on capacitors using the control strategy. A single-phase five-level FCMI model is currently being developed and constructed in the laboratory. Some of the experimental results are available.
Energy Technology Data Exchange (ETDEWEB)
NONE
2012-07-01
Within the international seminar of the Ostbayerisches Technologie-Transfer-Institut e.V. (OTTI) at 11th June, 2012 in Munich (Federal Republic of Germany), the following lectures were held: (1) Technical due diligence (Dietmar Obst); (2) Certification / rating system for large PV plants (Robert Pfatischer); (3) O and M requirements (Lars Rulf); (4) IR photography for large scale systems (Bernhard Weinreich); (5) New market models for PV systems - direct marketing and sales of PV electricity (Martin Schneider); (6) Needs and benefits for plant certification for grid connection and operation (Christoph Luetke-Lengerich); (7) Lare volume module testing / Screening in the field and workshop (Semir Merzoug); (8) Dismantling costs of large scale PV plants (Siegfried Schimpf).
Grid integrated distributed PV (GridPV).
Energy Technology Data Exchange (ETDEWEB)
Reno, Matthew J.; Coogan, Kyle
2013-08-01
This manual provides the documentation of the MATLAB toolbox of functions for using OpenDSS to simulate the impact of solar energy on the distribution system. The majority of the functions are useful for interfacing OpenDSS and MATLAB, and they are of generic use for commanding OpenDSS from MATLAB and retrieving information from simulations. A set of functions is also included for modeling PV plant output and setting up the PV plant in the OpenDSS simulation. The toolbox contains functions for modeling the OpenDSS distribution feeder on satellite images with GPS coordinates. Finally, example simulations functions are included to show potential uses of the toolbox functions. Each function in the toolbox is documented with the function use syntax, full description, function input list, function output list, example use, and example output.
An SCR inverter for electric vehicles
Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.
1980-01-01
An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.
Results from measurements on the PV-VENT systems at Lundebjerg[DENMARK
Energy Technology Data Exchange (ETDEWEB)
Oestergaard Jensen, S.
2001-05-01
The objective of the PV-VENT project was research, development, and tests in the following areas: 1. Develop and illustrate different ways of architectural integration of solar energy systems with combined PV power production and pre-heating of ventilation air in buildings, 2. Investigate the potential in pre-heating fresh air to the building by cooling the PV-panels with the fresh air and further to determine how much this cooling will increase the electrical performance of the PV-panels, 3. Develop and test air to air heat exchangers with an efficiency of 80% or above, 4. Develop and test fans and ventilation systems with an overall fan power demand of about 35 W, 5. Develop and test a direct coupling of the PV-panels to the fans in order to avoid the losses in an inverter, 6. Develop and test different ventilation systems utilizing the abovementioned features. Three different ways of integrating PV-panels with pre-heating of fresh air to the building have been demonstrated in Lundebjerg: a large PV-gable with amorphous PV-panels, a PV-facade with polycrystalline (c-Si) PV-panels and solar ventilation chimneys with polycrystalline (c-Si) PV-panels. Especially the latter feature, the solar ventilation chimney is a new and interesting concept as it allows for increased PV areas although the orientation of the building is not optimal for utilization of solar energy, as was the case in Lundebjerg. It is believed that the PV-VENT project has added important information and experience to the field of combining PV and ventilation systems. Information and experience that future systems of this type may benefit from. Several of the components from the project are believed to be able to contribute to set the standards for future PV and ventilation systems. Several of the components from the project is today commercial available and are used in ordinary building projects. (BA)
Institute of Scientific and Technical Information of China (English)
周剑敏
2014-01-01
The dual inverter-fed topology based on the open-end winding induction motor could effectively increase the output voltage and the output level. An electrical flow simulation model of the open-end winding induction motor was built by using the linear transformer and the controlled current source in the MATLAB/Simulink. The mathemati-cal model of the dual inverter-fed topology was analyzed. In view of the fault-tolerant performance,a SVPWM fault-tolerant control algorithm based on the reference voltage vector decoupling was proposed,and an experimental platform was constructed. The simulation results and experimental results verified the effectiveness of this simulation model and the fault-tolerant control algorithm.%基于开绕组电机的双逆变器拓扑能够有效提高输出电压等级与输出电平数，利用MATLAB环境下的线性变压器、受控电流源等模块搭建了开绕组电机的电气流仿真模型。分析了双逆变器拓扑的数学模型，针对其容错特性，提出一种基于参考电压矢量解耦的SVPWM容错控制算法，并搭建实验平台进行验证。仿真结果以及实验结果验证了开绕组异步电动机仿真模型以及容错控制算法的有效性。
PV-WEB: internet-based PV information tool
Energy Technology Data Exchange (ETDEWEB)
Cowley, P.
2003-07-01
This report gives details of a project to create a web-based information system on photovoltaic (PV) systems for the British PV Association (PV-UK) for use by decision makers in government, the utilities, and the housing and construction sectors. The project, which aims to provide an easily accessible tool for UK companies, promote PV technology, increase competitiveness, and identify market opportunities, is described. The design of the web site and its implementation and the evolution are discussed, along with the maintenance of the site by PV-UK and the opportunities offered to PV-UK Members.
Estimation of Maximum Allowable PV Connection to LV Residential Power Networks
DEFF Research Database (Denmark)
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2011-01-01
transformer or using solar inverters with new grid support features. This study presents a methodology for the estimation of maximum PV hosting capacity including IEC 60076-7 based thermal model of distribution transformer. Certain part of a real distribution network of Braedstrup suburban area in Denmark...... is used in simulation as a case study model. Furthermore, varying solutions (utilizing thermally upgraded insulation paper in transformers, reactive power services from solar inverters, etc.) are implemented on the network under investigation to examine PV penetration level and finally key results learnt......Maximum photovoltaic (PV) hosting capacity of low voltage (LV) power networks is mainly restricted by either thermal limits of network components or grid voltage quality resulted from high penetration of distributed PV systems. This maximum hosting capacity may be lower than the available solar...
Firefighter safety for PV systems: Overview of future requirements and protection systems
DEFF Research Database (Denmark)
Spataru, Sergiu; Sera, Dezso; Blaabjerg, Frede;
2013-01-01
An important and highly discussed safety issue for photovoltaic systems is that, as long as they are illuminated, a high voltage is present at the PV string terminals and cables between the string and inverters, independent of the state of the inverter's dc disconnection switch, which poses a risk...... shutdown procedures. This paper gives an overview on the most recent fire - and firefighter safety requirements for PV systems, with focus on system and module shutdown systems. Several solutions are presented, analyzed and compared by considering a number of essential characteristics, including...... for operators during maintenance or fire-fighting. One of the solutions is individual module shutdown by short-circuiting or disconnecting each PV module from the PV string. However, currently no standards have been adopted either for implementing or testing these methods, or doing an evaluation of the module...
Grid-connected Photovoltaic Micro-inverter with New Hybrid Control LLC Resonant Converter
DEFF Research Database (Denmark)
Xingkui, Mao; Qisheng, Huang; Qingbo, Ke;
2016-01-01
A high-efficiency photovoltaic (PV) micro-inverter consisting of two power stages i.e. a LLC resonant converter with a new hybrid control scheme and a dc-ac inverter is proposed, studied and designed in this paper. In the first power stage, the new hybrid control combining pulse-frequency modulat......A high-efficiency photovoltaic (PV) micro-inverter consisting of two power stages i.e. a LLC resonant converter with a new hybrid control scheme and a dc-ac inverter is proposed, studied and designed in this paper. In the first power stage, the new hybrid control combining pulse......-frequency modulation (PFM) and phase-shift pulse-width modulation (PS-PWM) is employed on a full-bridge LLC dc-dc converter, in order to achieve high efficiency when PV output voltage varies in a wide range. Moreover, a maximum power point tracking (MPPT) method based on power perturbation is implemented in the dc......-ac inverter. Therefore, the complexity of regulating LLC converter can be reduced effectively, and efficiency optimal design can be carried out through the proposed designing procedure for the resonant tank of LLC converter. Finally, a prototype of the proposed PV micro-inverter (PVMI) is developed with rated...
High Penetration PV: How High Can We Go?
Energy Technology Data Exchange (ETDEWEB)
2016-01-01
Brochure highlighting NREL's partnership with SolarCity and Hawaiian Electric (HECO) to increase the penetration of solar photovoltaics on the electricity grid. To better understand the potential impact of transient overvoltages due to load rejection, NREL collaborated with SolarCity and HECO to run a series of tests measuring the magnitude and duration of load rejection overvoltage events and demonstrating the ability of advanced PV inverters to mitigate their impacts.
A Comparison between Buck-Boost Inverter with and without Buffer Inductor
Directory of Open Access Journals (Sweden)
Purwadi Agus Darwito
2012-05-01
Full Text Available The electric vehicle inverter requires an induction motor drive with a high output of voltage and current to reduce the number of batteries used and in turn reduce the vehicle’s weight. In this paper compared two single Phase BuckBoost Inverter (SPBBI, that is between the SPBBI conventional topology with SPBBI new topology uses a buffer inductor. The results of comparison are expected that the new inverter topology can strengthen the voltage greater than the conventional inverter topology. The inverter’s components of capacitor and inductor were reconfigured. The circuit was simulated for various carrier and signal frequencies with various load. The simulation results of the proposed topology compared with the simulation results of conventional topologies commonly used in a variety of frequency and load values. It is shown that the output voltage and current can be strengthened significantly, with a value of more than five times of the output voltage compared to the conventional inverter. The new inverter topology is useful to be implemented for the electric vehicle.
Optimized Pulse Width Modulation for transformerless active-NPC inverters
DEFF Research Database (Denmark)
Achilladelis, Nikolaos; Koutroulis, Eftichios; Blaabjerg, Frede
2014-01-01
The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order to improve the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped (Active-NPC) transformerless inverters have the advantage of achieving better thermal balance among...... their power semiconductors. In this paper, a new modulation technique is proposed for optimally controlling the power switches employed in transformerless Active-NPC inverters. The design results demonstrate that compared to the existing PWM strategies, using the proposed method results in lower total power...
A New Green Power Inverter for Fuel Cells
DEFF Research Database (Denmark)
Andersen, Gert Karmisholt; Klumpner, Christian; Kjær, Søren Bækhøj;
2002-01-01
This paper presents a new grid connected inverter for fuel cells. It consists of a two stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25 V-45 V) this volt- age must be transformed to around 350-400 V in order to invert this dc power into ac...... startup. The inverter is controlled as a power factor controller with resistor emulation.Experimental results of converter efficiency, grid performance and fuel cell response are shown for a 1 kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92...
Closed Loop Analysis of Multilevel Inverter fed Drives
Directory of Open Access Journals (Sweden)
Bharath VS
2014-05-01
Full Text Available This paper deals with the simulation and implementation of multilevel inverter for drives application. Here the focuses will be on improving the efficiency of the multilevel inverter and quality of output voltage waveform. The circuit is developed towards high efficiency, high performance, and low cost, simple control scheme. Harmonics Elimination were implemented to reduce the Total Harmonics Distortion (THD value which is achieved by selecting appropriate switching angles. In this paper to determine the performance of rectifier, steady state analysis is done. Furthermore, the merits of multilevel inverter topology are inherited.Closed loop control is done to analysis the stability of the system.
Extreme Cost Reductions with Multi-Megawatt Centralized Inverter Systems
Energy Technology Data Exchange (ETDEWEB)
Schwabe, Ulrich [Alencon LLC; Fishman, Oleg [Alencon LLC
2015-03-20
The objective of this project was to fully develop, demonstrate, and commercialize a new type of utility scale PV system. Based on patented technology, this includes the development of a truly centralized inverter system with capacities up to 100MW, and a high voltage, distributed harvesting approach. This system promises to greatly impact both the energy yield from large scale PV systems by reducing losses and increasing yield from mismatched arrays, as well as reduce overall system costs through very cost effective conversion and BOS cost reductions enabled by higher voltage operation.
Integral inverter/battery charger for use in electric vehicles
Thimmesch, D.
1983-01-01
The design and test results of a thyristor based inverter/charger are discussed. A battery charger is included integral to the inverter by using a subset of the inverter power circuit components. The resulting charger provides electrical isolation between the vehicle propulsion battery and ac line and is capable of charging a 25 kWh propulsion battery in 8 hours from a 220 volt ac line. The integral charger employs the inverter commutation components at a resonant ac/dc isolated converter rated at 3.6 kW. Charger efficiency and power factor at an output power of 3.6 kW are 86% and 95% respectively. The inverter, when operated with a matching polyphase ac induction motor and nominal 132 volt propulsion battery, can provide a peak shaft power of 34 kW (45 ph) during motoring operation and 45 kW (60 hp) during regeneration. Thyristors are employed for the inverter power switching devices and are arranged in an input-commutated topology. This configuration requires only two thyristors to commutate the six main inverter thyristors. Inverter efficiency during motoring operation at motor shaft speeds above 450 rad/sec (4300 rpm) is 92-94% for output power levels above 11 KW (15 hp). The combined ac inverter/charger package weighs 47 kg (103 lbs).
PV power forecast using a nonparametric PV model
Almeida, Marcelo Pinho; Perpiñan Lamigueiro, Oscar; Narvarte Fernández, Luis
2015-01-01
Forecasting the AC power output of a PV plant accurately is important both for plant owners and electric system operators. Two main categories of PV modeling are available: the parametric and the nonparametric. In this paper, a methodology using a nonparametric PV model is proposed, using as inputs several forecasts of meteorological variables from a Numerical Weather Forecast model, and actual AC power measurements of PV plants. The methodology was built upon the R environment and uses Quant...
DEFF Research Database (Denmark)
Wang, Huai; Yang, Yongheng; Blaabjerg, Frede
2013-01-01
While 99% efficiency has been reported, the target of 20 years of service time imposes new challenge to cost-effective solutions for grid-connected photovoltaic (PV) inverters. Aluminum electrolytic capacitors are the weak-link in terms of reliability and lifetime in single-phase PV systems....... A reliability-oriented design guideline is proposed in this paper for the input capacitors in single-phase transformer-less PV inverters. The guideline ensures that the service time requirement is to be accomplished under different power levels and ambient temperature profiles. The theoretical analysis has been...
Comparison between three phase three and five level of flying capacitor multilevel inverter
Thanakodi, Suresh; Nazar, Nazatul Shiema Moh; Tzen, Bryon Sim Phin
2017-09-01
Multilevel inverter is increasingly being used in medium and high power application as conventional inverter have limited power hold and high total harmonics distortion. At present, there is a lot of literature regarding the topology and switching technique for multilevel inverter. The three common types of multilevel inverter are Diode Clamp Multilevel Inverter (DCMI), Cascaded Multilevel Inverter (CMI) and Flying Capacitor Multilevel Inverter (FCMI). This paper proposed the Three Phase Flying Capacitor Multilevel Inverter (FCMI) with Sinusoidal Pulse Width Modulation (SPWM) switching technique. This paper analysed the performance of FCMI and its characteristics based on parameters such as output phase voltage waveform and the total harmonics distortion (THD). The performance was accessed using Matlab/Simulink software. The result obtained shows that with higher number of levels for FCMI, the output THD was lowered due to near sinusoidal output waveform.
Energy Technology Data Exchange (ETDEWEB)
Zhao, Zilai [General Motors LLC, Detroit, MI (United States); Gough, Charles [General Motors LLC, Detroit, MI (United States)
2016-04-22
The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).
Inverted organic photosensitive devices
Energy Technology Data Exchange (ETDEWEB)
Forrest, Stephen R.; Bailey-Salzman, Rhonda F.
2016-12-06
The present disclosure relates to organic photosensitive optoelectronic devices grown in an inverted manner. An inverted organic photosensitive optoelectronic device of the present disclosure comprises a reflective electrode, an organic donor-acceptor heterojunction over the reflective electrode, and a transparent electrode on top of the donor-acceptor heterojunction.
Design and field performance of the KENETECH photovoltaic inverter system
Energy Technology Data Exchange (ETDEWEB)
Behnke, M.R. [KENETECH Windpower, Inc., Livermore, CA (United States)
1995-11-01
KENETECH Windpower has recently adapted the power conversion technology developed for the company`s variable speed wind turbine to grid-connected photovoltaic applications. KENETECH PV inverter systems are now in successful operation at the Sacramento Municipal Utility District`s (SMUD) Hedge Substation and the PVUSA-Davis site, with additional systems scheduled to be placed into service by the end of 1995 at SMUD, the New York Power Authority, Xerox Corporation`s Clean Air Now project, and the Georgia Tech Aquatic Center. The features of the inverter are described.
Energy Technology Data Exchange (ETDEWEB)
Ma, Mingyao; Hu, Haibing; Kutkut, Nasser; Batarseh, Issa; Shen, John; , Bkayrat, Raed
2017-08-01
A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled.
Energy Technology Data Exchange (ETDEWEB)
Hueser, Pius [Nova Energy GmbH, (Switzerland)
2007-06-15
This presentation is mainly about how the PV market in Europe has been growing, and which elements are going to determine if this market succeed or failed not only in Europe but also in the rest of the world. In the first part of this presentation, it is mentioned how in 2005 the development of some PV technologies triggered the PV market growth without any marketing control. Then, there are explained the aspects that changed such situation out of control, therefore, it emerged the beginning of the consolidation of this market. There are briefly explained those factors that are going to determine if this market succeed or failed in the future. Finally, there are given examples of some the PV investments. [Spanish] Esta presentacion habla principalmente de la manera en como ha crecido el Mercado de sistemas fotovoltaicos en Europa, asi tambien se mencionan los elementos fundamentales que determinaran el exito o fracaso de este mercado, no solamente en Europa sino tambien en el resto del mundo, en un futuro. En la primera parte de esta presentacion, se describe como en el 2005, debido al desarrollo de algunas tecnologias fotovoltaicas se desencadeno el crecimiento desenfrenado del mercado fotovoltaico. Despues, se explican los aspectos que hicieron que dicho crecimiento tomara su curso, teniendo como resultado el inicio de un mercado mas consolidado. Se explican brevemente los factores que determinaran si este mercado encuentra el exito o el fracaso en un futuro. Finalmente, se dan ejemplos de algunas adquisiciones fotovoltaicas.
Energy Technology Data Exchange (ETDEWEB)
Van Sark, W. [Sark Solar Energy Consultancy, Utrecht (Netherlands); Muizebelt, P. [New Energy Works, Utrecht (Netherlands); Cace, J. [Renewable Energy Company RenCom, Ouderkerk aan de Amstel (Netherlands)
2011-12-15
This report describes the results of an inventory of PV modules, inverters and system components that are available on the Dutch market. This inventory was conducted to feed the market with independent information and knowledge on available PV systems. The inventory was held in October 2011 [Dutch] Dit rapport beschrijft de resultaten van een inventarisatie van PV modules, omvormers en systeemcomponenten die op de Nederlandse markt verkrijgbaar zijn. Deze inventarisatie is uitgevoerd om de markt te voeden met onafhankelijke informatie en kennis over beschikbare PV-systemen. De inventarisatie heeft plaatsgevonden in de maand oktober 2011.
Energy Technology Data Exchange (ETDEWEB)
Baekhoej Kjaer, S.
2002-02-01
The 'SolcelleInverter' project starts with this state-of-the-art analysis of 27 different inverter topologies for use in photovoltaic applications. The main concern is the present status for inverters for single solar modules. Technologies for larger clusters of modules are also investigated. The possibility of combining a small decentralised and a big centralised unit is as well investigated. A series of topologies are discovered and this paper will present them. That includes solutions with and without transformers, systems for one or multiple modules, commercial solutions and solutions found in scientific papers and patents. (au)
DEFF Research Database (Denmark)
Ding, Tao; Li, Cheng; Yang, Yongheng
2017-01-01
Optimally dispatching Photovoltaic (PV) inverters is an efficient way to avoid overvoltage in active distribution networks, which may occur in the case of PV generation surplus load demand. Typically, the dispatching optimization objective is to identify critical PV inverters that have the most...... significant impact on the network voltage level. Following, it ensures the optimal set-points of both active power and reactive power for the selected inverters, guaranteeing the entire system operating constraints (e.g., the network voltage magnitude) within reasonable ranges. However, the intermittent...... against any possible realization within the uncertain PV outputs. In addition, the conic relaxation-based branch flow formulation and second-order cone programming based column-and-constraint generation algorithm are employed to deal with the proposed robust optimization model. Case studies on a 33-bus...
Testing for PV Reliability (Presentation)
Energy Technology Data Exchange (ETDEWEB)
Kurtz, S.; Bansal, S.
2014-09-01
The DOE SUNSHOT workshop is seeking input from the community about PV reliability and how the DOE might address gaps in understanding. This presentation describes the types of testing that are needed for PV reliability and introduces a discussion to identify gaps in our understanding of PV reliability testing.
PV potential and potential PV rent in European regions
DEFF Research Database (Denmark)
Hansen, Anders Chr.; Thorn, Paul
2013-01-01
The paper provides a GIS based model for assessing the potentials of photovoltaic electricity in Europe by NUTS 2 regions. The location specific energy potential per PV-‐panel area is estimated based on observations of solar irradiation, conversion efficiency, levelised costs and the social value...... of PV-‐electricity. Combined with the potential density of PV-‐panel area based on land cover and environental restrictions, the PV energy potential and the potential PV ressource rent is calculated. These calculations enbable the model to estimate the regional patterns at NUTS 2 level...
PV potential and potential PV rent in European regions
DEFF Research Database (Denmark)
Hansen, Anders Chr.; Thorn, Paul
2013-01-01
The paper provides a GIS based model for assessing the potentials of photovoltaic electricity in Europe by NUTS 2 regions. The location specific energy potential per PV-‐panel area is estimated based on observations of solar irradiation, conversion efficiency, levelised costs and the social value...... of PV-‐electricity. Combined with the potential density of PV-‐panel area based on land cover and environental restrictions, the PV energy potential and the potential PV ressource rent is calculated. These calculations enbable the model to estimate the regional patterns at NUTS 2 level...
Simulation Model developed for a Small-Scale PV-System in a Distribution Network
DEFF Research Database (Denmark)
Koch-Ciobotaru, C.; Mihet-Popa, Lucian; Isleifsson, Fridrik Rafn
2012-01-01
This paper presents a PV panel simulation model using the single-diode four-parameter model based on data sheet values. The model was implemented first in MATLAB/Simulink, and the results have been compared with the data sheet values and characteristics of the PV panels in standard test conditions....... Moreover to point out the strong dependency on ambient conditions and its influence on array operation and to validate simulation results with measured data a complex model has also been developed. A PV inverter model, using the same equations and parameters as in MATLAB/Simulink has also been developed...
Background information to the installers guide for small scale mains connected PV
Energy Technology Data Exchange (ETDEWEB)
NONE
2002-07-01
This report contains background information used by BRE, EA Technology, Halcrows and Sundog when compiling guidance for the UK's New and Renewable Energy Programme on the installation of small-scale photovoltaics (PV) in buildings. The report considers: relevant standards; general safety issues; fire and safety issues, including the fire resistance of PV modules; PV module ratings such as maximum voltage and maximum current; DC cabling; the DC disconnect; the DC junction box; fault analysis; general and AC side earthing; DC earthing; lightning and surge suppression; inverters; AC modules; AC systems; getting connection; mounting options; and installation issues.
Methods for Dynamic Analysis of Distribution Feeders with High Penetration of PV Generators
Energy Technology Data Exchange (ETDEWEB)
Nagarajan, Adarsh; Ayyanar, Raja
2016-11-21
An increase in the number of inverter-interfaced photovoltaic (PV) generators on existing distribution feeders affects the design, operation, and control of the distribution systems. Existing distribution system analysis tools are capable of supporting only snapshot and quasi-static analyses. Capturing the dynamic effects of PV generators during the variation in distribution system states is necessary when studying the effects of controller bandwidths, multiple voltage correction devices, and anti-islanding. This work explores the use of dynamic phasors and differential algebraic equations (DAE) for impact analysis of PV generators on the existing distribution feeders.
Reduced order modeling of grid-connected photovoltaic inverter systems
Wasynczuk, O.; Krause, P. C.; Anwah, N. A.
1988-04-01
This report summarizes the development of reduced order models of three-phase, line- and self-commutated inverter systems. This work was performed as part of the National Photovoltaics Program within the United States Department of Energy and was supervised by Sandia National Laboratories. The overall objective of the national program is to promote the development of low cost, reliable terrestrial photovoltaic systems for widespread use in residential, commercial and utility applications. The purpose of the effort reported herein is to provide reduced order models of three-phase, line- and self-commutated PV systems suitable for implementation into transient stability programs, which are commonly used to predict the stability characteristics of large-scale power systems. The accuracy of the reduced models is verified by comparing the response characteristics predicted therefrom with the response established using highly detailed PV system models in which the inverter switching is represented in detail.
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2017-01-01
As the penetration level of grid-connected PV systems increases, more advanced control functionality is demanded. In order to ensure smooth and friendly grid integration as well as enable more PV installations, the power generated by PV systems needs to be flexible and capable of: 1) limiting...... strategies for grid-connected PV inverters by modifying maximum power point tracking algorithms, where the PV power is regulated by changing the operating point of the PV system. In this way, no extra equipment is needed, being a cost-effective solution. Experiments on a 3-kW grid-connected PV system have...... been performed, where the developed flexible active power control functionalities are achieved per demands....
A Novel Hybrid Solution for Load Commutated Inverter-Fed Induction Motor Drives
Institute of Scientific and Technical Information of China (English)
continued
2004-01-01
Load commutated inverter (LCI)based synchronous motor drives have been traditionally used in very high power applications such as pumps, compressors and fans drives. The merits oft he load commutated inverter based system are resulted from the fact that since it employs converter grade thyristors and utilizes natural commutation of the thyristors. It provides simplicity, robustness, cost effectiveness, and very low switching losses.. Moreover, be-cause it has the currentsource inverter (CSI) topology, it has inherent advantages of CSI:
DEFF Research Database (Denmark)
Ding, Tao; Kou, Yu; Yang, Yongheng
2017-01-01
guaranteeing the entire system operating constraints (e.g., network voltage magnitude) within reasonable ranges in this paper. Meanwhile, optimal inverter dispatch is employed to further improve the PV integration by ensuring the optimal set-points of both active power and reactive power for the PV inverters...... be formulated as a mixed integer nonlinear nonconvex programming. Furthermore, a sequential interior-point method is utilized to solve this problem. Case studies on the IEEE 33-bus, 69-bus distribution networks and two practical distribution networks in China demonstrate the effectiveness of the proposed method....
Dynamic response evaluation of sensorless MPPT method for hybrid PV-DFIG wind turbine system
Directory of Open Access Journals (Sweden)
Danvu Nguyen
2016-01-01
Full Text Available This research proposes a sensorless Maximum Power Point Tracking (MPPT method for a hybrid Photovoltaic-Wind system, which consists of Photovoltaic (PV system and Doubly-Fed Induction Generator (DFIG Wind Turbine. In the hybrid system, the DC/DC converter output of the PV system is directly connected to the DC-link of DFIG’s back-to-back converter. Therefore, the PV inverter and its associated circuit can be removed in this structure. Typically, the PV power is monitored by using PV current sensor and PV voltage sensor for MPPT. In this paper, the powers of converters on grid side and rotor side of DFIG are used to estimate the PV power without the PV current sensor. That can efficiently reduce the cost of the hybrid system. The detailed analysis of the sensorless MPPT method, which includes derived equations and operation response, is also presented in this paper. In addition, an overview of PV-DFIG research in literature is stated to supply comprehensive knowledge of related research.
Institute of Scientific and Technical Information of China (English)
黄晓生; 陈为; 陈庆彬
2015-01-01
For the problems with traditional class E inverters, such as higher inductor losses, more sensitive to the resonant parameters and lower power limitation, a novel topology with dual (or even) class E inverters and power combination for wireless power transfer (WPT) applications was proposed. Coupled inductors were proposed to suppress the even-order harmonics currents and reduce loaded quality factor, so that the inverters can still work normally and high efficiently even with large deviations of resonant parameters. And magnetic integration of coupled inductors was proposed to reduce the numbers and losses of the magnetics. Series-series resonance compensation scheme was used for WPT system andπ-type (CLC) transconductance was used to ensure the constant output voltage and independence of voltage gain to the loads. A prototype with 1MHz operation frequency was designed and built to verify the feasibility and high performances of the proposed topology and to show that the voltage gain characteristics are independent with the loads and soft switching could be achieved at whole load ranges. The peak efficiency of the inverter reaches 92%.%针对现有用于无线电能传输系统的 E 类逆变器存在磁元件损耗大，谐振参数容差能力低以及输出功率有限的缺点，提出了一种新颖的双路(或偶数路)E类逆变器功率合成输出的无线电能传输系统拓扑，其逆变器利用耦合电感抑制偶次谐波电流并降低有载品质因数，在谐振参数存在较大偏差时仍然可以高效运行。同时，利用磁集成方法降低了磁元件数量与损耗。系统的补偿网络基于串串谐振补偿，并利用π型跨导使得系统电压增益与负载变化无关，保证输出电压恒定。利用一台1MHz 样机验证了所提出拓扑的可行性及优良性能。样机的电压增益基本不受负载变化的影响，其E类逆变器在全负载范围内均能实现软开关，
2013-01-01
The chapter provides an introduction to the basic concepts of Algebraic Topology with an emphasis on motivation from applications in the physical sciences. It finishes with a brief review of computational work in algebraic topology, including persistent homology.
Decentralized Optimal Dispatch of Photovoltaic Inverters in Residential Distribution Systems
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Dhople, Sairaj V.; Johnson, Brian B.; Giannakis, Georgios B.
2015-10-05
Summary form only given. Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are developed in this paper. It is known that conventional PV inverter controllers, which are designed to extract maximum power at unity power factor, cannot address secondary performance objectives such as voltage regulation and network loss minimization. Optimal power flow techniques can be utilized to select which inverters will provide ancillary services, and to compute their optimal real and reactive power setpoints according to well-defined performance criteria and economic objectives. Leveraging advances in sparsity-promoting regularization techniques and semidefinite relaxation, this paper shows how such problems can be solved with reduced computational burden and optimality guarantees. To enable large-scale implementation, a novel algorithmic framework is introduced - based on the so-called alternating direction method of multipliers - by which optimal power flow-type problems in this setting can be systematically decomposed into sub-problems that can be solved in a decentralized fashion by the utility and customer-owned PV systems with limited exchanges of information. Since the computational burden is shared among multiple devices and the requirement of all-to-all communication can be circumvented, the proposed optimization approach scales favorably to large distribution networks.
Karanayil, Baburaj; Agelidis, Vassilios; Pou Félix, Josep
2013-01-01
The life expectancy and long term reliability of grid-connected three-phase photovoltaic (PV) inverters can be increased by replacing the conventional electrolytic film capacitors by metallized polypropylene film capacitors. This paper presents a detailed evaluation of a three-phase grid-connected PV inverter performance when replacing the electrolytic capacitor with a minimum value of metallized polypropylene film capacitor-one. The minimum dc bus capacitance leads to larger voltage ripples....
Current-type flipped-Γ-source inverters
DEFF Research Database (Denmark)
Loh, Poh Chiang; Li, Ding; Blaabjerg, Frede
2012-01-01
Z-source inverters are innovative single-stage topologies proposed for flexible buck-boost energy conversion. To raise their gains and modulation ratios further, a number of variations have been introduced with some using magnetically coupled transformers or inductors. These variants are of inter......Z-source inverters are innovative single-stage topologies proposed for flexible buck-boost energy conversion. To raise their gains and modulation ratios further, a number of variations have been introduced with some using magnetically coupled transformers or inductors. These variants...... are of interest since they use lesser components. Their winding turns might however become too excessive for higher demanded gains. Avoiding this usual trend, a new family of current-type flipped-Γ-source inverters are proposed, whose common gain is raised by lowering, and not increasing, the winding turns...
Simulation and Implementation of Γ-Z Source Inverter
Directory of Open Access Journals (Sweden)
G.V.Sreekanth Reddy
2017-01-01
Full Text Available This venture "Simulation and Implementation of Γ-Z-Source Inverters" is made out of Voltage-sort Γ-Z source inverters are proposed in this letter. They utilize a remarkable Γ-molded impedance arrange for boosting their yield voltage notwithstanding their standard voltage buck conduct. Contrasting them and different topologies, the proposed inverters utilize lesser parts and a coupled transformer for delivering the high-pick up and regulation proportion all the while. The got pick up can be tuned by changing the turns proportion γΓZ of the transformer inside the limited scope of 1 < γΓZ ≤ 2. This prompts to lesser twisting turns at high pick up, as compared to other related topologies
2015-07-01
with small-scale power storage can maintain power quality in islanded mode with minimal use of the generators during non-optimal (e.g. cloud covered...inverter ( advantage of short term storage ) and enables microgrid upgrade of legacy generator assets (integration of inverter and generator controllers...microgrid stability, and can further be integrated with the distributed power storage to address intermittent loss of PV energy as when a cloud passes
Improved inverted Stepanov apparatus
Berkman, S.; Temple, H. E.
1979-01-01
Modifications in inverted Stepanov process improve heat transfer and energy efficiency in growing silicon ribbon crystals. Using system, silicon is directly heated by induction, minimizing heat transfer and contamination problems.
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang;
2014-01-01
This paper introduces a new 3-phase Y-source inverter whose gain is presently not matched by classical impedance-network-based inverters operating at the same duty ratio. The proposed network uses a tightly coupled transformer with three windings. By squeezing the shoot-through range while keeping....... This design flexibility was proven mathematically, and is supported by simulations carried out to prove the concept and validate the analysis....
Power control flexibilities for grid-connected multi-functional photovoltaic inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2014-01-01
This paper explores the next-generation Photo- Voltaic (PV) system integration issues at a high penetration level, where the grid is becoming more decentralized and vulnerable. Therefore, the PV systems are expected to be more controllable with higher efficiency and higher reliability. Provision...... to generate appropriate references for the inner current control loop. The references depend on the system conditions and also specific demands from both system operators and customers. Besides, this power control strategy can be implemented in a commercial PV inverter as standardized functions, and also...
Improved PV system reliability results from surge evaluations at Sandia National Laboratories
Energy Technology Data Exchange (ETDEWEB)
Russell H. Bonn; Sigifredo Gonzalez
2000-04-11
Electrical surges on ac and dc inverter power wiring and diagnostic cables have the potential to shorten the lifetime of power electronics. These surges may be caused by either nearby lightning or capacitor switching transients. This paper contains a description of ongoing surge evaluations of PV power electronics and surge mitigation hardware at Sandia.
Semistar Invertibility on Integral Domains
Institute of Scientific and Technical Information of China (English)
Marco Fontana; Giampaolo Picozza
2005-01-01
A natural development of the recent work about semistar operations leads to investigate the concept of "semistar invertibility". Here, we show the existence of a "theoretical obstruction" for extending many results, proved for star-invertibility, to the semistar case. For this reason, we introduce two distinct notions of invertibility in the semistar setting (called *-invertibility and quasi-*-invertibility), we discuss the motivations of these "two levels" of invertibility and we extend, accordingly, many classical results proved for the d-, v-, t- and w-invertibility.
High-Frequency Link Inverter for Fuel Cells Based on Multiple-Carrier PWM
Institute of Scientific and Technical Information of China (English)
无
2004-01-01
HIGH-FREQUENCY (I-IF) ac link inverter topologies, with or without soft switching, have important practical advantages compared to more conventional dc link inverters in terms of isolation, size of magnetics, and other properties. It is possible to obtain these basic advantages directly in a conventional PWM inverter with trans former-coupled output, but only if the transformer can handle the low modulating frequency. HF link topologies have not been common for medium power (1 to 20kW), largely because of the number of power stages and control complexity.
Directory of Open Access Journals (Sweden)
Chetanya Gupta
2014-07-01
Full Text Available The use of multilevel inverters has become popular in recent years for high-power applications. Multilevel Inverters are power converter systems composed by an array of power semiconductor sources that when properly connected and controlled can generate a multistep voltage waveform with variable and controllable frequency, phase and amplitude. This study deals with the comparison of a 7-level inverter with a 9-level inverter system; the voltage source inverters (VSI are modelled and simulated using MATLAB Simulink and the results are presented. The test results verify the effectiveness of the proposed strategy in terms of computational efficiency as well as the capability of the inverter to produce very low distorted voltage with low-switching losses. This research aims to extend the knowledge about the performance of different clamped multilevel inverter through harmonic analysis. Simulations results validate up to the mark performance of the mentioned topologies.
Directory of Open Access Journals (Sweden)
Dhananjay Choudhary
2014-08-01
Full Text Available The two basic topologies of switch mode DC-DC converters (Buck and Boost are analyzed with a view of their use in PV (photovoltaic systems, as the photovoltaic generator exhibits non-linear characteristics due to the change in environmental condition and load variation. As the efficiency of PV panels is low it becomes mandatory to extract maximum power from the PV panel at a given period of time. Several MPPT algorithms with different types of converters are being proposed for extracting maximum power from the PV panel. It is found that the nature of load plays an important role in the choice of topology. This paper investigates the implementation issues of Incremental Conductance method with Buck and Boost Converters. Mathematical analysis and desirable steady-state operating point of the converters are derived to give satisfactory maximum power point tracking operation.
Energy Technology Data Exchange (ETDEWEB)
Stettler, S.; Toggweiler, P. [Enecolo AG, Moenchaltorf (Switzerland); Ruoss, D.; Schudel, P. [Envision, Lucerne (Switzerland); Kottmann, A.; Steinle, F. [BE Netz AG, Lucerne (Switzerland)
2008-03-15
This final report elaborated for the Swiss Federal Office of Energy (SFOE) takes a look at the results of a project carried out to determine the costs for facility management, to estimate future cost development and to propose activities for the further reduction of the operation and maintenance costs of photovoltaic systems. Information on the cost situation was collected by literature study, as well as in interviews and surveys with photovoltaic (PV) experts and the owners of PV installations. The discussion of the results at a workshop with about 20 Swiss PV experts is noted. The results are presented and discussed. These show that operating costs per kWh decrease with the size of the PV system. Figures are quoted. The major part of the costs are quoted as being those for spare parts, especially for the inverter. The authors are of the opinion that, in future, costs for facility management will further decrease, as they are partly linked to capital and insurance costs. Potential for optimisation is said to exist in several areas of facility management such as, for example, in system monitoring and fast reaction in the case of malfunctions.
DEFF Research Database (Denmark)
Loh, Poh Chiang; Duan, Na; Liang, Chao;
2007-01-01
can only either perform voltage-buck or boost operation with buck-boost operation usually attained by adding additional actively controlled dc-dc converters. Although effective, the adding of dc-dc converters introduces additional active switches, which somehow dilute advantages associated...... with a reduced component count topology. Proposing alternative configurations with a reduced active semiconductor count, this paper discusses the systematic design of a number of Z-source B4 inverters, whose buck-boost capability is attained passively by inserting LC elements and clamping diodes. Visually...
Institute of Scientific and Technical Information of China (English)
刘芳; 赖良发; 苏建徽
2012-01-01
根据推挽型光伏并网微逆变器的拓扑结构特点提出了一种适合该拓扑的控制策略,详细分析了该控制策略的原理,推导了该控制策略下并网电流与其参考信号之间的约束关系,借助MATLAB仿真软件验证了控制策略的可行性.该控制策略使推挽型光伏并网微逆变器工作于电流源模式下,具有较高的并网电流质量.%By analyzing the topology of the push - pull micro - inverter for grid - connected PV, a new control strategy of the inverter is proposed. The control strategy is then analyzed in detail. The relationship between the grid - connected current and its reference signal are derived simultaneously. Furthermore, a MATLAB -based circuit is built to verify the feasibility of the proposed control strategy. It is shown through simulation results that as the push - pull micro - inverter operates in current source mode, it may have higher quality of the grid - connected current in a great degree.
Analysis and carrier-based modulation of Z-source NPC inverters
Dehghan, Seyed Mohammad; Mohamadian, Mustafa; Gharekhani, Reza
2012-08-01
Multi-level neutral-point-clamped (NPC) inverters are widely used in high and medium voltage applications. However, these inverters are only buck-type converters. Recently z-source NPC inverters have been proposed as the buck-boost three-level inverter. New inverters use a z-source network as the input stage. This article analyses the features and limitations of two main topologies of z-source NPC inverters (dual z-source network NPC inverter and single z-source network NPC inverter). The low-frequency ripple of the inductor current and the capacitor voltage of the z-source networks in the z-source NPC inverters are surveyed. This article also proposes two novel PWM methods for the z-source NPC inverters, which can be easily implemented experimentally. In the proposed methods, generated switching signals for the conventional NPC inverter are modified for the z-source NPC inverter using a simple logic circuit considering the boost factors and the power sharing ratio. The performance of the proposed simple PWM methods is verified by simulation and experimental results.
Topological insulators and topological superconductors
Bernevig, Andrei B
2013-01-01
This graduate-level textbook is the first pedagogical synthesis of the field of topological insulators and superconductors, one of the most exciting areas of research in condensed matter physics. Presenting the latest developments, while providing all the calculations necessary for a self-contained and complete description of the discipline, it is ideal for graduate students and researchers preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with simple concepts such as Berry phases, Dirac fermions, Hall conductance and its link to topology, and the Hofstadter problem of lattice electrons in a magnetic field. It moves on to explain topological phases of matter such as Chern insulators, two- and three-dimensional topological insulators, and Majorana p-wave wires. Additionally, the book covers zero modes on vortices in topological superconductors, time-reversal topological superconductors, and topological responses/field theory and topolo...
PV water pumping: NEOS Corporation recent PV water pumping activities
Energy Technology Data Exchange (ETDEWEB)
Lane, C.
1995-11-01
NEOS Corporation has been very active in PV-powered water pumping, particularly with respect to electric utilities. Most of the recent activity has been through the Photovoltaic Services Network (PSN). The PSN is an independent, not-for-profit organization comprised of all types of electric utilities: rural electric coops, public power districts, investor-owned utilities, and power marketing agencies. The PSN`s mission is to work pro-actively to promote utility involvement in PV through education and training. PV information is distributed by the PSN in three primary forms: (1) consultation with PSN technical service representatives: (2) literature generated by the PSN; and (3) literature published by other organizations. The PSN can also provide assistance to members in developing PV customer service programs. The PSN`s product support activities include consolidation of information on existing packaged PV systems and facilitation of the development of new PV product packages that meet utility-defined specifications for cost performance, and reliability. The PSN`s initial product support efforts will be focused on commercially available packaged PV systems for a variety of off-grid applications. In parallel with this effort, if no products exist that meet the PSN`s functional specifications, the PSN will initiate the second phase of product development support process by encouraging the development of new packaged systems. Through these services and product support activities, the PSN anticipates engaging all segments for the PV industry, thus providing benefits to PV systems suppliers as well as local PV service contractors.This paper describes field testing of pv power systems for water pumping.
Directory of Open Access Journals (Sweden)
Ayse KOCALMIS BILHAN
2013-01-01
Full Text Available A space vector PWM method for a two level inverter is proposed in this paper. A two level inverter using space vector modulation strategy has been modeled and simulated with a passive R-L load. Photovoltaic cells are used as DC source for input of two-level inverter. Simulation results are presented for various operation conditions to verify the system model. In this paper, MATLAB/Simulink package program has been used for modeling and simulation of PV cells and two-level space vector pulse width modulation (SVPWM inverter.
Topological Methods for Visualization
Energy Technology Data Exchange (ETDEWEB)
Berres, Anne Sabine [Los Alamos National Lab. (LANL), Los Alamos, NM (United Stat
2016-04-07
This slide presentation describes basic topological concepts, including topological spaces, homeomorphisms, homotopy, betti numbers. Scalar field topology explores finding topological features and scalar field visualization, and vector field topology explores finding topological features and vector field visualization.
Solution to avoid unwanted trips for PV systems connected to LV network facing voltage sags
Energy Technology Data Exchange (ETDEWEB)
Le Thi Minh, Chau; Tran-Quoc, Tuan; Kieny, Christophe [IDEA, Saint-Martin-d' Heres (France); Bacha, Seddik [Grenoble Electric Engineering Laboratory, Saint-Martin-d' Heres (France); Cabanac, Philippe; Grenard, Sebastien [Electricite de France, Clamart (France). Direction des Etudes et Recherches; Goulielmakis, David [Schneider Electric, Grenoble (France). Projects and Engineering Center
2011-07-01
Most of photovoltaic (PV) systems connected to low voltage (LV) distribution networks have a single-phase connection. The analysis of the behavior of these single-phase connection. The analysis of the behavior of these single-phase PV inverters facing voltage sags caused by short circuits is of major concern. These behaviors depend on fault types, fault location, types of grid architecture, grid protection systems (with or without auto-recloser system) and PV protection types. Therefore, the first investigation of this work is to study comprehensively the behaviors of PV systems connected to real LV networks facing voltage sags in different scenarios by taking into account the real network protection. Furthermore, future power systems with a large share of PV systems connected could be severely affected if several of the PV systems are tripping at the same instant. From these results of simulation, unwanted trip cases, due to the disconnection protection of PV systems are identified. Finally, a simple efficient solution by using the voltage-time characteristic for PV system is proposed. The validation by simulations shows the efficiency of the proposed solution. (orig.)
Challenges in thermal design of industrial single-phase power inverter
Directory of Open Access Journals (Sweden)
Ninković Predrag
2016-01-01
Full Text Available This paper presents the influence of thermal aspects in design process of an industrial single-phase inverter, choice of its topology and components. Stringent design inputs like very high overload level, demand for natural cooling and very wide input voltage range have made conventional circuit topology inappropriate therefore asking for alternative solution. Different power losses calculations in semiconductors are performed and compared, outlining the guidelines how to choose the final topology. Some recommendations in power magnetic components design are given. Based on the final project, a 20kVA single-phase inverter for thermal power plant supervisory and control system is designed and commissioned.
Sensorless PV Array Diagnostic Method for Residential PV Systems
DEFF Research Database (Denmark)
Sera, Dezso; Spataru, Sergiu; Mathe, Laszlo
2011-01-01
This work proposes a temperature and irradiance sensorless diagnostic method suitable for small residential PV installations, focusing on detection of partial shadows. The method works by detection of failures in crystalline silicone PV arrays by concomitant monitoring of some of their key parame...
2014-01-01
This paper proposes a dynamic modeling and control strategy for a grid connected hybrid wind and photovoltaic (PV) energy system inter-connected to electrical grid through power electronic interface. A gearless permanent magnet synchronous generator (PMSG) is used to capture the maximum wind energy. The PV and wind systems are connected dc-side of the voltage source inverter through a boost converter individually and maintain a fixed dc output at dc link. A proper control sche...
Interband cascade (IC) photovoltaic (PV) architecture for PV devices
Energy Technology Data Exchange (ETDEWEB)
Yang, Rui Q.; Tian, Zhaobing; Mishima, Tetsuya D.; Santos, Michael B.; Johnson, Matthew B.; Klem, John F.
2015-10-20
A photovoltaic (PV) device, comprising a PV interband cascade (IC) stage, wherein the IC PV stage comprises an absorption region with a band gap, the absorption region configured to absorb photons, an intraband transport region configured to act as a hole barrier, and an interband tunneling region configured to act as an electron barrier. An IC PV architecture for a photovoltaic device, the IC PV architecture comprising an absorption region, an intraband transport region coupled to the absorption region, and an interband tunneling region coupled to the intraband transport region and to the adjacent absorption region, wherein the absorption region, the intraband transport region, and the interband tunneling region are positioned such that electrons will flow from the absorption region to the intraband transport region to the interband tunneling region.
Goodman, Sue E
2009-01-01
Beginning Topology is designed to give undergraduate students a broad notion of the scope of topology in areas of point-set, geometric, combinatorial, differential, and algebraic topology, including an introduction to knot theory. A primary goal is to expose students to some recent research and to get them actively involved in learning. Exercises and open-ended projects are placed throughout the text, making it adaptable to seminar-style classes. The book starts with a chapter introducing the basic concepts of point-set topology, with examples chosen to captivate students' imaginations while i
Perra, Andre
1992-04-01
The use of pulse-width-modulated (PWM) inverter technology by on-line uninterruptible power supplies (UPSs) of 250 VA-750 kVA rating improves transient performance, lowers harmonic distortion, and enhances nonlinear load performance. An account is presently given of the means employed for optimization of a PWM inverter used in a multi-kHz UPS. By using computer modeling to optimize the feedback control loop, the best level of response was furnished, while minimizing switching losses and achieving the highest level of efficiency.
Price Development of Photovoltaic Modules, Inverters and Systems in the Netherlands
Sark, W.G.J.H.M. van; Muizebelt, P.; Cace, J.; Vries, A. de; Rijk, P. de
2014-01-01
Since 2010 the Dutch photovoltaic (PV) market has been growing fast, with around doubling of installed capacity in 2011 and 2012. Four quarterly inventories have been made in 2012 for modules, inverters, and systems that are presently available for purchase in the Netherlands. We have found that the
Price development of photovoltaic modules, inverters, and systems in the Netherlands in 2012
Van Sark, Wilfried G J H M|info:eu-repo/dai/nl/074628526; Muizebelt, Peter; Cace, Jadranka; de Vries, Arthur; de Rijk, Peer
2014-01-01
Since 2010 the Dutch photovoltaic (PV) market has been growing fast, with around doubling of installed capacity in 2011 and 2012. Four quarterly inventories have been made in 2012 for modules, inverters, and systems that are presently available for purchase in the Netherlands. We have found that the
Low Voltage Ride-Through of Single-Phase Transformerless Photovoltaic Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2014-01-01
, e.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults are explored in this paper. Control strategies with reactive power injections...
Low voltage ride-through of single-phase transformerless photovoltaic inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2013-01-01
.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults are explored in this paper. Control strategies with reactive power injections are also...
Passive P-control of a grid-connected photovoltaic inverter
Meza, C.; Jeltsema, D.; Scherpen, J. M. A.; Biel, D.
2008-01-01
A passive P-controller for a single-phase single-stage grid-connected photovoltaic inverter is presented. Explicit dependance of the PV array parameters on external unpredictable variables such as temperature and solar irradiance is avoided by extending the control scheme with a reference estimator.
Passive P-control of a grid-connected photovoltaic inverter
Meza, C.; Jeltsema, D.; Scherpen, J. M. A.; Biel, D.
2008-01-01
A passive P-controller for a single-phase single-stage grid-connected photovoltaic inverter is presented. Explicit dependance of the PV array parameters on external unpredictable variables such as temperature and solar irradiance is avoided by extending the control scheme with a reference estimator.
The Frequency Fluctuation Impact Analysis for Droop Controlled Grid-connecting Inverter in Microgrid
DEFF Research Database (Denmark)
Wei, Feng; Sun, Kai; Guan, Yajuan
2016-01-01
No matter with PV or batteries as DC source, the droop controlled grid-connecting inverter (DC-GCI) has been widely used in microgrid. As the bandwidth of the outer active and reactive power control loop is designed to be much slower when comparing to the inner voltage/current loop of the DCGCI...
Grid Integration of Large PV Power Systems Using HVDC Link
Directory of Open Access Journals (Sweden)
Gamal Sowilam
2016-09-01
Full Text Available This paper explores the interconnection of large scale Photo-Voltaic (PV systems to the grid though a High Voltage Direct Current (HVDC link. HVDC link is recently utilized for transmission lines longer than 50 km. It is usually utilized to interconnect two asynchronous grids with the same or different frequencies while avoiding stability disturbances greatly. A suitable Maximum Power Point Tracking (MPPT techniques is employed to control the performance of the integrated PV system. The system of the HVDC link has two 12-pulse converter using thyristor-bridges. The delay and the extinction angles at the rectifier and the inverter units control the flow and the quantity of the transmitted power from the PV system into the grid. Fixed capacitors and filters are used to provide the AC side with the required reactive power and reduce the harmonic contents. For evaluation purposes, different simulation investigations are carried out with a detailed modeling using the MATLAB. These tests corroborate the efficacy of HVDC link for integrating large PV systems to electrical grids.
Scalable Optimization Methods for Distribution Networks with High PV Integration
Energy Technology Data Exchange (ETDEWEB)
Guggilam, Swaroop S.; Dall' Anese, Emiliano; Chen, Yu Christine; Dhople, Sairaj V.; Giannakis, Georgios B.
2016-07-01
This paper proposes a suite of algorithms to determine the active- and reactive-power setpoints for photovoltaic (PV) inverters in distribution networks. The objective is to optimize the operation of the distribution feeder according to a variety of performance objectives and ensure voltage regulation. In general, these algorithms take a form of the widely studied ac optimal power flow (OPF) problem. For the envisioned application domain, nonlinear power-flow constraints render pertinent OPF problems nonconvex and computationally intensive for large systems. To address these concerns, we formulate a quadratic constrained quadratic program (QCQP) by leveraging a linear approximation of the algebraic power-flow equations. Furthermore, simplification from QCQP to a linearly constrained quadratic program is provided under certain conditions. The merits of the proposed approach are demonstrated with simulation results that utilize realistic PV-generation and load-profile data for illustrative distribution-system test feeders.
Models for a stand-alone PV system
DEFF Research Database (Denmark)
Hansen, A.D.; Sørensen, Poul Ejnar; Hansen, L.H.;
2001-01-01
Energy Centre Denmark. The study is carried out at Risø National Laboratory with the main purpose to establish a library of simple mathematical models for each individual element of a stand-alone PVsystem, namely solar cells, battery, controller, inverter and load. The models for PV module and battery...... that provides a graphical interface for building models as modular block diagrams. Thenon-linear behaviour of the battery, observed in the measurements, is investigated and compared to the KiBaM model's performance. A set of linear Black box models are estimated based on the battery measurements....... The performance of the best linear Blackbox model is compared to the KiBaM model. A validation of each of the implemented mathematical model is performed by an interactive analysis and comparison between simulation results and measurements, acquired from the stand-alone PV system at Risø....
PV-HYBRID and MINI-GRID. Proceedings
Energy Technology Data Exchange (ETDEWEB)
NONE
2006-07-01
design and validation of PV-hybrid sysem technology for rural electrification programmes in remote areas of Europe (Xavier Valive); (17) Analysis of inverter-controlled Island grids - transient simulations with ATP-EMTP and PowerFactory (Martin Braun); (18) Design of a PV-diesel hybrid energy system (William Lawrance); (19) Hybrid storage systems in PV stand alone applications impact on sizing and performance (Julien Labbe); (20) Sizing and analysis of a small hydro PV hybrid system for the rural electrification in developing countries (Joseph Kenfack); (21) Identification of dynamic equivalents for microgrids with high penetration of solar energy using ANNs (F.O. Resende); (22) Constructing village PV hybrid power systems on a wide-scale in Western China: Experience gained (Henrik Bindner); (23) Experiences with large-scale construction of PH hybrid village power systems in Western China (Winfried Klinghammer); (24) A detailed data based analysis of the behaviour of a 10+5+20 KW wind-PV-diesel hybrid sysem (Luis M. Arribas); (25) PV hybrid village electrification in French Guyana (Christian Dumbs); (26) Energy consumption patterns in village PV-diesel-hybrid systems (Javier Munoz); (27) From Subag to Ponelo hybrid photovoltaic-diesel system in Indonesia, lessons learned (Adjat Sudradjat); (28) PV diesel hybrid system in rural Africa - an inter-disciplinary approach (Markus Landau); (29) Making PV-diesel hybrids and PV or wind mini-grids sustainable in remote developing country sites: the Nabouwalu case (Philippe Veyan); (30) Mini-grid for an isolated island sandwip in Bangladesh (B.K. Bala).
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
Future photovoltaic (PV) inverters are expected to comply with more stringent grid codes and reliability requirements, especially when a high penetration degree is reached, and also to lower the cost of energy. A junction temperature control concept is proposed in this study for the switching...... devices in a single-phase PV inverter in order to reduce the junction temperature stress, and thus to achieve improved reliability of a PV inverter. The thermal stresses of the switching devices are analysed during low voltage ride-through operation with different levels of reactive power injection......, allowing an optimal design of the proposed control scheme with controlled mean junction temperature and reduced junction temperature swings. The effectiveness of the control method in terms of both thermal performance and electrical performance is validated by the simulations and experiments, respectively...
Directory of Open Access Journals (Sweden)
Nuntawat Thitichaiworakorn
2016-01-01
Full Text Available Medium-scale photovoltaic (PV systems using cascaded H-bridge multilevel inverters have a capability to perform individual maximum power point tracking (MPPT for each PV panel or each small group of panels, resulting in minimization of both power losses from panel mismatch and effect of partial shading. They also provide high power quality, modularity, and possibility of eliminating dc-dc boost stage and line-frequency transformer. However, each PV panel in the system is subjected to a double-line-frequency voltage ripple at the dc-link which reduces the MPPT efficiency. This paper proposes a dc-link voltage ripple reduction by third-harmonic zero-sequence voltage injection for improving the MPPT efficiency. Moreover, a control method to achieve individual MPPT control of each inverter cell is also presented. The validity and effectiveness of the proposed methods were verified by computer simulation.
Direct Torque Control of Induction Motor Drive Fed from a Photovoltaic Multilevel Inverter
Directory of Open Access Journals (Sweden)
Mahrous Ahmed
2014-09-01
Full Text Available This paper presents Direct Torque Control (DTC using Space Vector Modulation (SVM for an induction motor drive fed from a photovoltaic multilevel inverter (PV-MLI. The system consists of two main parts PV DC power supply (PVDC and MLI. The PVDC is used to generate DC isolated sources with certain ratios suitable for the adopted MLI. Beside the hardware system, the control system which uses the torque and speed estimation to control the load angle and to obtain the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control methods. The voltage vector is then generated by a hybrid multilevel inverter by employing space vector modulation (SVM. The inverter high quality output voltage which leads to a high quality IM performances. Besides, the MLI switching losses is very low due to most of the power cell switches are operating at nearly fundamental frequency. Some selected simulation results are presented for system validation.
Inverter communications using output signal
Energy Technology Data Exchange (ETDEWEB)
Chapman, Patrick L.
2017-02-07
Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.
Three-Level Z-Source Inverters Using a Single LC Impedance Network
DEFF Research Database (Denmark)
Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng
2007-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their effectiveness in achieving voltage buck-boost conversion, existing three-level Z-source inverters use...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...... can conveniently be implemented using a generic "alternative phase opposition disposition" carrier-based modulator with the appropriate triplen offset and time advance/delay added. The designed inverters, having a reduced passive component count, are lastly tested in simulation and experimentally...
Inverting the Linear Algebra Classroom
Talbert, Robert
2014-01-01
The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…
Control of Cascaded Multilevel Inverters
Institute of Scientific and Technical Information of China (English)
无
2004-01-01
Abstract-A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one DC voltage source. This new inverter can operateas a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-fre-quency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation resuits demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering). Index Terms-Cascaded inverter, multilevel inverter, three-level inverter.
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2009-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Zsource inverters are either too costly...
Garcerá Sanfeliú, Gabriel; González Medina, Raul; Figueres Amorós, Emilio; Sandia Paredes, Jesús
2012-01-01
In photovoltaic (PV) double-stage grid-connected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. In the proposed overall control structur...
Speedometers for PV generators; Drehzahlmesser fuer PV-Generatoren
Energy Technology Data Exchange (ETDEWEB)
Fritze, Peter; Weinreich, Bernhard [Solarschmiede GmbH, Muenchen (Germany). Engineering-Abt.
2011-05-31
To measure the generator power of an installed PV system, it is not enough to look into the specifications of hte module producers. Fast and independent data can be provided by characteristic curve meters.
PV in a sports arena; PV im Hexenkessel
Energy Technology Data Exchange (ETDEWEB)
Hoeche, B.
2008-05-19
The German soccer club Werder Bremen is reconstructing its stadium. Apart from higher spectator comfort and a better atmosphere, there will also be PV systems on the roof and external walls of the arena. (orig.)
Buchstaber, Victor M
2015-01-01
This book is about toric topology, a new area of mathematics that emerged at the end of the 1990s on the border of equivariant topology, algebraic and symplectic geometry, combinatorics, and commutative algebra. It has quickly grown into a very active area with many links to other areas of mathematics, and continues to attract experts from different fields. The key players in toric topology are moment-angle manifolds, a class of manifolds with torus actions defined in combinatorial terms. Construction of moment-angle manifolds relates to combinatorial geometry and algebraic geometry of toric v
Directory of Open Access Journals (Sweden)
Pąk Karol
2015-02-01
Full Text Available Let us recall that a topological space M is a topological manifold if M is second-countable Hausdorff and locally Euclidean, i.e. each point has a neighborhood that is homeomorphic to an open ball of E n for some n. However, if we would like to consider a topological manifold with a boundary, we have to extend this definition. Therefore, we introduce here the concept of a locally Euclidean space that covers both cases (with and without a boundary, i.e. where each point has a neighborhood that is homeomorphic to a closed ball of En for some n.
Franz, Marcel
2013-01-01
Topological Insulators, volume six in the Contemporary Concepts of Condensed Matter Series, describes the recent revolution in condensed matter physics that occurred in our understanding of crystalline solids. The book chronicles the work done worldwide that led to these discoveries and provides the reader with a comprehensive overview of the field. Starting in 2004, theorists began to explore the effect of topology on the physics of band insulators, a field previously considered well understood. However, the inclusion of topology brings key new elements into this old field. Whereas it was
Warner, S
1989-01-01
Aimed at those acquainted with basic point-set topology and algebra, this text goes up to the frontiers of current research in topological fields (more precisely, topological rings that algebraically are fields).The reader is given enough background to tackle the current literature without undue additional preparation. Many results not in the text (and many illustrations by example of theorems in the text) are included among the exercises. Sufficient hints for the solution of the exercises are offered so that solving them does not become a major research effort for the reader. A comprehensive bibliography completes the volume.
Inverted organic photovoltaic cells.
Wang, Kai; Liu, Chang; Meng, Tianyu; Yi, Chao; Gong, Xiong
2016-05-21
The advance in lifestyle, modern industrialization and future technological revolution are always at high expense of energy consumption. Unfortunately, there exist serious issues such as limited storage, high cost and toxic contamination in conventional fossil fuel energy sources. Instead, solar energy represents a renewable, economic and green alternative in the future energy market. Among the photovoltaic technologies, organic photovoltaics (OPVs) demonstrate a cheap, flexible, clean and easy-processing way to convert solar energy into electricity. However, OPVs with a conventional device structure are still far away from industrialization mainly because of their short lifetime and the energy-intensive deposition of top metal electrode. To address the stability and cost issue simultaneously, an inverted device structure has been introduced into OPVs, bridging laboratory research with practical application. In this review, recent progress in device structures, working mechanisms, functions and advances of each component layer as well their correlations with the efficiency and stability of inverted OPVs are reviewed and illustrated.
2015-01-01
A simple power electronic interface based on the line-commutated inverter (LCI) has been developed in order to inject sinusoidal current to the grid for single-phase grid-connected photovoltaic (PV) energy generation systems. The proposed inverter facilitates controlling the injecting/grid current with a controllable power factor in contrast to the conventional LCI system. It is achieved that the total harmonic distortion (THD) of the injecting currents for the different firin...
Experimental Evaluation of Load Rejection Over-Voltage from Grid-Tied Solar Inverters
Energy Technology Data Exchange (ETDEWEB)
Nelson, Austin; Hoke, Andy, Chakraborty, Sudipta; Ropp, Michael; Chebahtah, Justin; Wang, Trudie; Zimmerly, Brian
2017-05-11
This paper investigates the impact of load rejection over-voltage (LRO) from commercially available grid-tied photovoltaic (PV) solar inverters. LRO can occur when a local feeder or breaker opens and the power output from a distributed energy resource exceeds the load power. Simplified models of current controlled inverters can over-predict over-voltage magnitudes, thus it is useful to quantify testing. The load rejection event was replicated using a hardware testbed at the National Renewable Energy Laboratory (NREL), and a set of commercially available PV inverters was tested to quantify the impact of LRO for a range of generation-to-load ratios. The magnitude and duration of the over-voltage events are reported in this paper along with a discussion of characteristic inverter output behavior. The results for the inverters under test showed that maximum over-voltage magnitudes were less than 200 percent of nominal voltage, and much lower in many test cases. These research results are important because utilities that interconnect inverter-based DER need to understand their characteristics under abnormal grid conditions.
Extended SVM algorithms for multilevel trans-Z-source inverter
Directory of Open Access Journals (Sweden)
Aida Baghbany Oskouei
2016-03-01
Full Text Available This paper suggests extended algorithms for multilevel trans-Z-source inverter. These algorithms are based on space vector modulation (SVM, which works with high switching frequency and does not generate the mean value of the desired load voltage in every switching interval. In this topology the output voltage is not limited to dc voltage source similar to traditional cascaded multilevel inverter and can be increased with trans-Z-network shoot-through state control. Besides, it is more reliable against short circuit, and due to several number of dc sources in each phase of this topology, it is possible to use it in hybrid renewable energy. Proposed SVM algorithms include the following: Combined modulation algorithm (SVPWM and shoot-through implementation in dwell times of voltage vectors algorithm. These algorithms are compared from viewpoint of simplicity, accuracy, number of switching, and THD. Simulation and experimental results are presented to demonstrate the expected representations.
Mukherjee, Amiya
2015-01-01
This book presents a systematic and comprehensive account of the theory of differentiable manifolds and provides the necessary background for the use of fundamental differential topology tools. The text includes, in particular, the earlier works of Stephen Smale, for which he was awarded the Fields Medal. Explicitly, the topics covered are Thom transversality, Morse theory, theory of handle presentation, h-cobordism theorem, and the generalised Poincaré conjecture. The material is the outcome of lectures and seminars on various aspects of differentiable manifolds and differential topology given over the years at the Indian Statistical Institute in Calcutta, and at other universities throughout India. The book will appeal to graduate students and researchers interested in these topics. An elementary knowledge of linear algebra, general topology, multivariate calculus, analysis, and algebraic topology is recommended.
Models for a stand-alone PV system[Photovoltaic
Energy Technology Data Exchange (ETDEWEB)
Hansen, A.D.; Soerensen, P.; Hansen, L.H.; Bindner, H.
2000-12-01
This report presents a number of models for modelling and simulation of a stand-alone photovoltaic (PV) system with a battery bank verified against a system installed at Risoe National Laboratory. The work has been supported by the Danish Ministry of Energy, as a part of the activities in the Solar Energy Centre Denmark. The study is carried out at Risoe National Laboratory with the main purpose to establish a library of simple mathematical models for each individual element of a stand-alone PV system, namely solar cells, battery, controller, inverter and load. The models for PV module and battery are based on the model descriptions found in the literature. The battery model is developed at UMASS and is known as the Kinetic Battery Model (KiBaM). The other component models in the PV system are based on simple electrical knowledge. The implementation is done using Matlab/Simulink, a simulation program that provides a graphical interface for building models as modular block diagrams. The non-linear behaviour of the battery, observed in the measurements, is investigated and compared to the KiBaM model's performance. A set of linear Black box models are estimated based on the battery measurements. The performance of the best linear Black box model is compared to the KiBaM model. A validation of each of the implemented mathematical model is performed by an interactive analysis and comparison between simulation results and measurements, acquired from the stand-alone PV system at Risoe. (au)
Quantum-confined Stark effect in band-inverted junctions
Díaz-Fernández, A.; Domínguez-Adame, F.
2017-09-01
Topological phases of matter are often characterized by interface states, which were already known to occur at the boundary of a band-inverted junction in semiconductor heterostructures. In IV-VI compounds such interface states are properly described by a two-band model, predicting the appearance of a Dirac cone in single junctions. We study the quantum-confined Stark effect of interface states due to an electric field perpendicular to a band-inverted junction. We find a closed expression to obtain the interface dispersion relation at any field strength and show that the Dirac cone widens under an applied bias. Thus, the Fermi velocity can be substantially lowered even at moderate fields, paving the way for tunable band-engineered devices based on band-inverted junctions.
High Efficiency Non-isolated Three Port DC-DC Converter for PV-Battery Systems
DEFF Research Database (Denmark)
Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe
2016-01-01
This paper presents a nonisolated Three Port Converter (TPC) with a unidirectional port for photovoltaic (PV) panels and a bidirectional port for energy storage. With the proposed topology single power conversion is performed between each port, so high efficiencies are obtained. A theoretical...
High Efficiency Non-isolated Three Port DC-DC Converter for PV-Battery Systems
DEFF Research Database (Denmark)
Tomas Manez, Kevin; Anthon, Alexander; Zhang, Zhe;
2016-01-01
This paper presents a nonisolated Three Port Converter (TPC) with a unidirectional port for photovoltaic (PV) panels and a bidirectional port for energy storage. With the proposed topology single power conversion is performed between each port, so high efficiencies are obtained. A theoretical ana...
A Comparative Modelling Study of PWM Control Techniques for Multilevel Cascaded Inverter
Directory of Open Access Journals (Sweden)
A. TAHRI
2005-01-01
Full Text Available The emergence of multilevel converters has been in increase since the last decade. These new types of converters are suitable for high voltage and high power application due to their ability to synthesize waveforms with better harmonic spectrum. Numerous topologies have been introduced and widely studied for utility and drive applications. Amongst these topologies, the multilevel cascaded inverter was introduced in Static Var compensation and drive systems. This paper investigates several control techniques applied to the Multilevel Cascaded Inverter in order to ensure an efficient voltage utilization and better harmonic spectrum. A modelling and control strategy of a single phase Multilevel Cascaded Inverter is also investigated. Computer simulation results using Matlab program are reported and discussed together with a comparative study of the different control techniques of multilevel cascaded inverter.Moreover, experimental results are carried out on a scaled down prototype to prove the effectiveness of the proposed analysis.
Trimode Power Converter optimizes PV, diesel and battery energy sources
Osullivan, George; Bonn, Russell; Bower, Ward
1994-12-01
Conservatively, there are 100,000 localities in the world waiting for the benefits that electricity can provide, and many of these are in climates where sunshine is plentiful. With these locations in mind a prototype 30 kW hybrid system has been assembled at Sandia to prove the reliability and economics of photovoltaic, diesel and battery energy sources managed by an autonomous power converter. In the Trimode Power Converter the same power parts, four IGBT's with an isolation transformer and filter components, serve as rectifier and charger to charge the battery from the diesel; as a stand-alone inverter to convert PV and battery energy to AC; and, as a parallel inverter with the diesel-generator to accommodate loads larger than the rating of the diesel. Whenever the diesel is supplying the load, an algorithm assures that the diesel is running at maximum efficiency by regulating the battery charger operating point. Given the profile of anticipated solar energy, the cost of transporting diesel fuel to a remote location and a five year projection of load demand, a method to size the PV array, battery and diesel for least cost is developed.
Sizing and Simulation of PV-Wind Hybrid Power System
Directory of Open Access Journals (Sweden)
Mustafa Engin
2013-01-01
Full Text Available A sizing procedure is developed for hybrid system with the aid of mathematical models for photovoltaic cell, wind turbine, and battery that are readily present in the literature. This sizing procedure can simulate the annual performance of different kinds of photovoltaic-wind hybrid power system structures for an identified set of renewable resources, which fulfills technical limitations with the lowest energy cost. The output of the program will display the performance of the system during the year, the total cost of the system, and the best size for the PV-generator, wind generator, and battery capacity. Security lightning application is selected, whereas system performance data and environmental operating conditions are measured and stored. This hybrid system, which includes a PV, wind turbine, inverter, and a battery, was installed to supply energy to 24 W lamps, considering that the renewable energy resources of this site where the system was installed were 1700 Wh/m2/day solar radiation and 3.43 m/s yearly average wind speed. Using the measured variables, the inverter and charge regulator efficiencies were calculated as 90% and 98%, respectively, and the overall system’s electrical efficiency is calculated as 72%. Life cycle costs per kWh are found to be $0.89 and LLP = 0.0428.
Status and Needs of Power Electronics for Photovoltaic Inverters: Summary Document
Energy Technology Data Exchange (ETDEWEB)
WEST, RICK; MAUCH, KONRAD; QIN,YU CHIN; MOHAN,NED; BONN, RUSSELL H.
2002-04-01
Photovoltaic inverters are the most mature of any DER inverter, and their mean time to first failure (MTFF) is about five years. This is an unacceptable MTFF and will inhibit the rapid expansion of PV. With all DER technologies, (solar, wind, fuel cells, and microturbines) the inverter is still an immature product that will result in reliability problems in fielded systems. The increasing need for all of these technologies to have a reliable inverter provides a unique opportunity to address these needs with focused R&D development projects. The requirements for these inverters are so similar that modular designs with universal features are obviously the best solution for a ''next generation'' inverter. A ''next generation'' inverter will have improved performance, higher reliability, and improved profitability. Sandia National Laboratories has estimated that the development of a ''next generation'' inverter could require approximately 20 man-years of work over an 18- to 24-month time frame, and that a government-industry partnership will greatly improve the chances of success.
Current Harmonics from Single-Phase Grid-Connected Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2016-01-01
is focused on the impacts of the power factor and the feed-in grid current level on the quality of the feed-in grid current from single-phase inverters. As a consequence, an internal model principle based high performance current control solution is tailor-made and developed for single-phase grid...... factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis......-connected systems to produce high quality currents in different operation conditions, where a design procedure is also provided. The developed current controller in this paper can achieve a minimum steady-state error while maintaining a relatively fast transient response, and also being feasible in other single...
Power Quality Improvement of an Off-Grid Versatile PV System
Directory of Open Access Journals (Sweden)
D. Bini Sherlin
2014-03-01
Full Text Available Photovoltaic systems are trusted to be the future wave of alternate source of energy. This paper presents a versatile PV generation system that enables to supply both AC as well as DC loads in addition to providing back-up supply for the AC load. The back-up supply is provided by charging a battery. The inverter is controlled using hysteresis current control method that contains the current ripple within the two hysteresis bands. Thereby the harmonic content in the inverter output is lowered and also provides quality power. The performance of the proposed system is verified through simulation.
Ternifi, T. Z.; Atik, L.; Bachir, G.; Belarbi, A. W.; Petit, P.; Aillerie, M.
2016-07-01
This paper presents a parallel topology of a modular photovoltaic inverter, allowing a marked improvement in the quality of the output energy signal. This is a feature of much interest in practical applications as it will produce an output signal with very low harmonic distortions. In this contribution, we describe the inverter, then the bipolar pulse width modulation (PWM) strategy, which will bevalidateby simulation. Finally, some experimental results are exposed to illustrate our work.
Grid-connected photovoltaic power systems: survey of inverter and related protection equipments
Energy Technology Data Exchange (ETDEWEB)
Ishikawa, T
2002-12-15
This report for the International Energy Agency (IEA) made by Task 5 of the Photovoltaic Power Systems (PVPS) programme reports on a survey made on inverter and related protection equipment. The mission of the Photovoltaic Power Systems Programme is to enhance the international collaboration efforts which accelerate the development and deployment of photovoltaic solar energy. Task 5 deals with issues concerning grid-interconnection and distributed PV power systems. This report summarises the data obtained from survey of recent inverter technology and inverter protection equipment for grid interconnected PV systems. The results are based on the surveys using a questionnaire to identify the current status of grid-interconnection inverters. This report is to serve as a reference for those interested in installing grid-connected PV systems, electric utility company personnel, manufacturers and researchers. The results of the survey are presented and discussed. Technical and financial data is reviewed and two appendices provide details on the results obtained and those institutions involved in the survey.
Energy Technology Data Exchange (ETDEWEB)
Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-08-31
Given that next-generation infrastructures will contain large numbers of grid-connected inverters and these interfaces will be satisfying a growing fraction of system load, it is imperative to analyze the impacts of power electronics on such systems. However, since each inverter model has a relatively large number of dynamic states, it would be impractical to execute complex system models where the full dynamics of each inverter are retained. To address this challenge, we derive a reduced-order structure-preserving model for parallel-connected grid-tied three-phase inverters. Here, each inverter in the system is assumed to have a full-bridge topology, LCL filter at the point of common coupling, and the control architecture for each inverter includes a current controller, a power controller, and a phase-locked loop for grid synchronization. We outline a structure-preserving reduced-order inverter model for the setting where the parallel inverters are each designed such that the filter components and controller gains scale linearly with the power rating. By structure preserving, we mean that the reduced-order three-phase inverter model is also composed of an LCL filter, a power controller, current controller, and PLL. That is, we show that the system of parallel inverters can be modeled exactly as one aggregated inverter unit and this equivalent model has the same number of dynamical states as an individual inverter in the paralleled system. Numerical simulations validate the reduced-order models.
Energy Technology Data Exchange (ETDEWEB)
Mohr, Malte
2011-03-04
Fuel cells represent an important potential alternative to conventional thermal-mechanical- electrical energy transformations due to their highly efficient direct conversion of chemical energy, i.e. hydrogen or natural gas into electrical energy. Inverter systems that feed electrical power from fuel cells into the grid must convert the direct current of the fuel cell into the alternating current of the grid. In addition, these inverters have to adapt the different voltages of the fuel cell system to the grid. Inverter systems for fuel cells can be seen as an own field of research. Only a few results from other fields of research in power electronic circuits in the medium power range - like converters for electrical drives or power supplies - can be applied to inverter systems for fuel cells due to the different technical constraints. In this thesis, different topologies of appropriate inverter systems in the medium power range of 20 kW and higher are analyzed and compared to each other. This study includes transformerless inverters as well as two-stage inverter systems with high frequency transformers (DC/DC converter combined with an inverter). In the beginning, this thesis shows the electrical characteristics of the fuel cell and of the main inverter components like power semiconductors and passive components. In addition, the principles of power semiconductor losses and methods of the semiconductor power loss calculation are shown. This work does not focus on the dimensioning of the passive components like capacitors, chokes and transformers. The main principles of the dimensioning of the passive components are shown but are not analyzed in detail. The summary of the demands of a fuel cell inverter system is followed by the analytical analysis of the different inverter topologies. In addition, the semiconductor loss calculations for the topologies will be derived. To gain practical experience and to verify parts of the theoretical analysis, the converters
Test Protocols for Advanced Inverter Interoperability Functions - Appendices
Energy Technology Data Exchange (ETDEWEB)
Johnson, Jay Dean [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ralph, Mark E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ellis, Abraham [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2013-11-01
Distributed energy resources (DER) such as photovoltaic (PV) systems, when deployed in a large scale, are capable of influencing significantly the operation of power systems. Looking to the future, stakeholders are working on standards to make it possible to manage the potentially complex interactions between DER and the power system. In 2009, the Electric Power Research Institute (EPRI), Sandia National Laboratories (SNL) with the U.S. Department of Energy (DOE), and the Solar Electric Power Association (SEPA) initiated a large industry collaborative to identify and standardize definitions for a set of DER grid support functions. While the initial effort concentrated on grid-tied PV inverters and energy storage systems, the concepts have applicability to all DER. A partial product of this on-going effort is a reference definitions document (IEC TR 61850-90-7, Object models for power converters in distributed energy resources (DER) systems) that has become a basis for expansion of related International Electrotechnical Commission (IEC) standards, and is supported by US National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP). Some industry-led organizations advancing communications protocols have also embraced this work. As standards continue to evolve, it is necessary to develop test protocols to independently verify that the inverters are properly executing the advanced functions. Interoperability is assured by establishing common definitions for the functions and a method to test compliance with operational requirements. This document describes test protocols developed by SNL to evaluate the electrical performance and operational capabilities of PV inverters and energy storage, as described in IEC TR 61850-90-7. While many of these functions are not now required by existing grid codes or may not be widely available commercially, the industry is rapidly moving in that direction. Interoperability issues are already apparent as
Test Protocols for Advanced Inverter Interoperability Functions – Main Document
Energy Technology Data Exchange (ETDEWEB)
Johnson, Jay Dean [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ralph, Mark E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ellis, Abraham [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2013-11-01
Distributed energy resources (DER) such as photovoltaic (PV) systems, when deployed in a large scale, are capable of influencing significantly the operation of power systems. Looking to the future, stakeholders are working on standards to make it possible to manage the potentially complex interactions between DER and the power system. In 2009, the Electric Power Research Institute (EPRI), Sandia National Laboratories (SNL) with the U.S. Department of Energy (DOE), and the Solar Electric Power Association (SEPA) initiated a large industry collaborative to identify and standardize definitions for a set of DER grid support functions. While the initial effort concentrated on grid-tied PV inverters and energy storage systems, the concepts have applicability to all DER. A partial product of this on-going effort is a reference definitions document (IEC TR 61850-90-7, Object models for power converters in distributed energy resources (DER) systems) that has become a basis for expansion of related International Electrotechnical Commission (IEC) standards, and is supported by US National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP). Some industry-led organizations advancing communications protocols have also embraced this work. As standards continue to evolve, it is necessary to develop test protocols to independently verify that the inverters are properly executing the advanced functions. Interoperability is assured by establishing common definitions for the functions and a method to test compliance with operational requirements. This document describes test protocols developed by SNL to evaluate the electrical performance and operational capabilities of PV inverters and energy storage, as described in IEC TR 61850-90-7. While many of these functions are not currently required by existing grid codes or may not be widely available commercially, the industry is rapidly moving in that direction. Interoperability issues are already
Locational Sensitivity Investigation on PV Hosting Capacity and Fast Track PV Screening
Energy Technology Data Exchange (ETDEWEB)
Ding, Fei; Mather, Barry; Ainsworth, Nathan; Gotseff, Peter; Baker, Kyri
2016-05-05
A 15% PV penetration threshold is commonly used by utilities to define photovoltaic (PV) screening methods where PV penetration is defined as the ratio of total solar PV capacity on a line section to peak load. However, this method doesn't take into account PV locational impact or feeder characteristics that could strongly change the feeder's capability to host PVs. This paper investigates the impact of PV location and phase connection type on PV hosting capacity, and then proposes a fast-track PV screening approach that leverages various PV hosting capacity metric responding to different PV locations and types. The proposed study could help utilities to evaluate PV interconnection requests and also help increase the PV hosting capacity of distribution feeders without adverse impacts on system voltages.
Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System
Santiago, Walter
2004-01-01
NASA Glenn Research Center (GRC) has been involved in the research and development of high speed flywheel systems for small satellite energy storage and attitude control applications. One research and development area has been the minimization of the switching noise produced by the pulsed width modulated (PWM) inverter that drives the flywheel permanent magnet motor/generator (PM M/G). This noise can interfere with the flywheel M/G hardware and the system avionics hampering the full speed performance of the flywheel system. One way to attenuate the inverter switching noise is by placing an AC filter at the three phase output terminals of the inverter with the filter neutral point connected to the DC link (DC bus) midpoint capacitors. The main benefit of using an AC filter in this fashion is the significant reduction of the inverter s high dv/dt switching and its harmonics components. Additionally, common mode (CM) and differential mode (DM) voltages caused by the inverter s high dv/dt switching are also reduced. Several topologies of AC filters have been implemented and compared. One AC filter topology consists of a two-stage R-L-C low pass filter. The other topology consists of the same two-stage R-L-C low pass filter with a series connected trap filter (an inductor and capacitor connected in parallel). This paper presents the analysis, design and experimental results of these AC filter topologies and the comparison between the no filter case and conventional AC filter.
Experimental Realizations of Magnetic Topological Insulator and Topological Crystalline Insulator
Xu, Suyang
2013-03-01
Over the past few years the experimental research on three-dimensional topological insulators have emerged as one of the most rapidly developing fields in condensed matter physics. In this talk, we report on two new developments in the field: The first part is on the dynamic interplay between ferromagnetism and the Z2 topological insulator state (leading to a magnetic topological insulator). We present our spin-resolved photoemission and magnetic dichroic experiments on MBE grown films where a hedgehog-like spin texture is revealed on the magnetically ordered surface of Mn-Bi2Se3 revealing a Berry's phase gradient in energy-momentum space of the crystal. A chemically/electrically tunable Berry's phase switch is further demonstrated via the tuning of the spin groundstate in Mn-Bi2Se3 revealed in our data (Nature Physics 8, 616 (2012)). The second part of this talk describes our experimental observation of a new topological phase of matter, namely a topological crystalline insulator where space group symmetries replace the role of time-reversal symmetry in an otherwise Z2 topological insulator predicted in theory. We experimentally investigate the possibility of a mirror symmetry protected topological phase transition in the Pb1-xSnxTe alloy system, which has long been known to contain an even number of band inversions based on band theory. Our experimental results show that at a composition below the theoretically predicted band inversion, the system is fully gapped, whereas in the band-inverted regime, the surface exhibits even number of spin-polarized Dirac cone states revealing mirror-protected topological order (Nature Communications 3, 1192 (2012)) distinct from that observed in Z2 topological insulators. We discuss future experimental possibilities opened up by these new developments in topological insulators research. This work is in collaboration with M. Neupane, C. Liu, N. Alidoust, I. Belopolski, D. Qian, D.M. Zhang, A. Richardella, A. Marcinkova, Q
Asymmetrical Γ-Source Inverters
DEFF Research Database (Denmark)
Wei, Mo; Poh Chiang, Loh; Blaabjerg, Frede
2014-01-01
, inverters with coupled transformers have been introduced, but they usually lead to high turns ratio, and hence many winding turns, at high gain. An alternative would then be the asymmetrical Γ-source inverters proposed in this paper, whose gain is raised by lowering their turns ratio toward unity. The input...... current drawn by the proposed inverters is smoother and, hence, more adaptable by the source. Theories and experimental results have been presented in this paper for validating the concepts proposed....
Gas cooled traction drive inverter
Chinthavali, Madhu Sudhan
2013-10-08
The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.
Gas cooled traction drive inverter
Energy Technology Data Exchange (ETDEWEB)
Chinthavali, Madhu Sudhan
2016-04-19
The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.
DEFF Research Database (Denmark)
A. Kristensen, Anders Schmidt; Damkilde, Lars
2007-01-01
. A way to solve the initial design problem namely finding a form can be solved by so-called topology optimization. The idea is to define a design region and an amount of material. The loads and supports are also fidefined, and the algorithm finds the optimal material distribution. The objective function...... dictates the form, and the designer can choose e.g. maximum stiness, maximum allowable stresses or maximum lowest eigenfrequency. The result of the topology optimization is a relatively coarse map of material layout. This design can be transferred to a CAD system and given the necessary geometrically...... refinements, and then remeshed and reanalysed in other to secure that the design requirements are met correctly. The output of standard topology optimization has seldom well-defined, sharp contours leaving the designer with a tedious interpretation, which often results in less optimal structures. In the paper...
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2010-01-01
of embedded EZ-source inverters that can produce the same gain as the Z-source inverters but with smoother and smaller current/voltage maintained across the dc input source and within the impedance network. These latter features are attained without using any additional passive filter, which surely...... is a favorable advantage, since an added filter will raise the system cost and, at times, can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage- and current-type inverters with each of them tested...
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, Poh Chiang; Gao, F.
2008-01-01
-voltage oscillations to the system. Therefore, Z-source inverters are in effect safer and less complex, and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family of embedded EZ...... since an added filter will raise the system cost, and at times can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage and current-type inverters with each of them tested experimentally using a number...
Applications of cascade multilevel inverters
Institute of Scientific and Technical Information of China (English)
彭方正; 钱照明
2003-01-01
Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.
Applications of cascade multilevel inverters
Institute of Scientific and Technical Information of China (English)
彭方正; 钱照明
2003-01-01
Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.
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.
Directory of Open Access Journals (Sweden)
M.R. Banaei
2014-09-01
Full Text Available Multilevel inverters are suggested to obtain high quality output voltage. In this paper, a new hybrid configuration is proposed, obtained by cascading one four switches H-bridge cell with a family of multilevel inverters. In addition, by the use of specific sequence for value of DC sources named Fibonacci series, asymmetrical topology of proposed inverter is introduced. Main advantages are that proposed inverter has least Peak Inverse Voltage (PIV than other conventional multilevel converters in both symmetric and asymmetric modes. Also, this topology doubles the number of output levels using only one cascaded four switches H-bridge cell. The PCI-1716 DAQ using PC has been used to generate switching pulses in experimental results. For presenting valid performance of proposed configuration, simulation results carried out by MATLAB/SIMULINK software and the validity of the proposed multilevel inverter is verified by experimental results.
Energy Technology Data Exchange (ETDEWEB)
Chaudhuri, T. [ABB Secheron SA, Geneve (Switzerland)
2010-07-01
This article focuses on DC/AC power inverters. The author first reviews the numerous multi-level topologies developed since 1980 in power electronics, with their advantages and disadvantages. The objective of the new topologies - named 'cross-connected' - is the improvement of the signal quality of an 'active neutral point clamped' (ANPC) five-level inverter used in wind power plants, while limiting as far as possible the number of additional components in order to get the highest possible reliability at moderate cost. The author describes the details of the technology and compares several variants. A new family of power inverters has been created.
Search for Majorana fermions in topological superconductors.
Energy Technology Data Exchange (ETDEWEB)
Pan, Wei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shi, Xiaoyan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hawkins, Samuel D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Klem, John Frederick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-10-01
The goal of this project is to search for Majorana fermions (a new quantum particle) in a topological superconductor (a new quantum matter achieved in a topological insulator proximitized by an s-wave superconductor). Majorana fermions (MFs) are electron-like particles that are their own anti-particles. MFs are shown to obey non-Abelian statistics and, thus, can be harnessed to make a fault-resistant topological quantum computer. With the arrival of topological insulators, novel schemes to create MFs have been proposed in hybrid systems by combining a topological insulator with a conventional superconductor. In this LDRD project, we will follow the theoretical proposals to search for MFs in one-dimensional (1D) topological superconductors. 1D topological superconductor will be created inside of a quantum point contact (with the metal pinch-off gates made of conventional s-wave superconductors such as niobium) in a two-dimensional topological insulator (such as inverted type-II InAs/GaSb heterostructure).
Warner, S
1993-01-01
This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.
Arnold, Vladimir; Zorich, Anton
1999-01-01
This volume offers an account of the present state of the art in pseudoperiodic topology-a young branch of mathematics, born at the boundary between the ergodic theory of dynamical systems, topology, and number theory. Related topics include the theory of algorithms, convex integer polyhedra, Morse inequalities, real algebraic geometry, statistical physics, and algebraic number theory. The book contains many new results. Most of the articles contain brief surveys on the topics, making the volume accessible to a broad audience. From the Preface by V.I. Arnold: "The authors … have done much to s
Milewski, Emil G
2013-01-01
REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Topology includes an overview of elementary set theory, relations and functions, ordinals and cardinals, topological spaces, continuous functions, metric spaces and normed spaces, co
PV system testing and standards
DeBlasio, Richard
1999-03-01
The U.S. Department of Energy (DOE) PV Program System Performance and Engineering Project is being conducted by The National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), Southwest Technology Development Institute (SWTDI), and Florida Solar Energy Center (FSEC). It provides PV system, subsystem, and component-level technology-performance characterization testing; test-method development and validation; national and international consensus standards and codes development, test-facility product certification, and laboratory-accreditation program implementation; and information exchange and technical assistance to the PV community. Emphasis is placed on reducing technical and infrastructural barriers to system acceptance, reducing life-cycle cost of systems, providing systems-engineering best practices and guidelines, and leading the national effort in performance and reliability testing, and consensus standards, codes, and certification program development and implementation—thereby ensuring that PV systems meet customers' needs and expectations. A summary of project activities, accomplishments, and future plans is provided and highlighted by an overview of PV system test-procedure and standards development.
Low concentrator PV optics optimization
Sharp, Leonard; Chang, Ben
2008-08-01
Purpose: Cost reduction is a major focus of the solar industry. Thin film technologies and concentration systems are viable ways to reducing cost, with unique strengths and weakness for both. Most of the concentrating PV work focuses on high concentration systems for reducing energy cost. Meanwhile, many believe that low concentrators provide significant cost reduction potential while addressing the mainstream PV market with a product that acts as a flat panel replacement. This paper analyzes the relative benefit of asymmetric vs. symmetric optics for low-concentrators in light of specific PV applications. Approach: Symmetric and asymmetric concentrating PV module performance is evaluated using computer simulation to determine potential value across various geographic locations and applications. The selected optic design is modeled against standard cSi flat panels and thin film to determine application fit, system level energy density and economic value. Results: While symmetric designs may seem ideal, asymmetric designs have an advantage in energy density. Both designs are assessed for aperture, optimum concentration ratio, and ideal system array configuration. Analysis of performance across climate specific effects (diffuse, direct and circumsolar) and location specific effects (sunpath) are also presented. The energy density and energy production of low concentrators provide a compelling value proposition. More significantly, the choice of optics for a low concentrating design can affect real world performance. With the goal of maximizing energy density and return on investment, this paper presents the advantages of asymmetric optic concentration and illustrates the value of this design within specific PV applications.
Single stage buck-boost DC-AC neutral point clamped inverter
DEFF Research Database (Denmark)
Mo, Wei; Loh, Poh Chiang; Andrew, A.;
2012-01-01
This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence...... windings thus preventing the core from saturation; lowers the voltage stresses and power losses of inverter switches and reduces the sizes of filtering devices and as well as obtains better output performance compared to the original two-level Z-source inverters. A phase disposition pulse width modulation...
A Review of Novel Leakage Current Suppression Techniques for Transformerless Photovoltaic Inverters
Institute of Scientific and Technical Information of China (English)
WU Weiyang; GUO Xiaoqiang
2012-01-01
In recent years, the transformerless PV inverters have been paid more attention due to cost and size reduction, as well as efficiency improvement compared with the conventional transformer ones. Leakage current suppression is one of the most important techniques for transformerless grid connected photovoltaic systems. The objective of this paper is to present a comprehensive review of the recently developed solution to the leakage current reduction. First of all, the common-mode model of the PV system is described to explain how the leakage current generates.
Harmonic Analysis and Design of Embedded Z-Source Inverter for Induction Motor Drives
Directory of Open Access Journals (Sweden)
P.Kannan
2014-03-01
Full Text Available This Project deals with an Embedded Z-source inverter to control the three phase induction motor. The Z-source inverters are recent topological options for buck–boost energy conversion with a number of possible voltage and current-type circuitries. The common advantage of Z-source inverter and Embedded Z-source inverter is the inclusion of an LC impedance network, placed between the dc input source and inverter bridge. The drawbacks of the conventional Z-source inverters are more harmonic, less reliable, more diode blocking voltage and capacitor size also high. By introducing Embedded Z-source inverters, the drawbacks of the conventional Z-source inverter can be eliminated and also gain produced is same as that of Z-source inverter. It can produce smoother and smaller current or voltage maintained across the dc input source without using any additional passive filter, less cost and low harmonic distortion. The project is further carried to control the induction motor drive which is used in paper mills, textile mills and cement industries etc.
Research on a New Type of Energy Feedback Cascade Multilevel Inverter System
Directory of Open Access Journals (Sweden)
Yu Jianhua
2013-01-01
Full Text Available Traditional cascade multilevel inverter can only transmit one-direction of energy. This paper proposes a new cascade multilevel inverter topology and control strategy based on part units to realize the energy feedback. By using PWM converter to replace uncontrollable converter in part units of the traditional inverter, and combining the inverter with H-bridge inverter, the two-direction running of the cascade inverter is realized. A double closed loop control strategy is used to obtain fine control characteristic of input current. The carrier phase-shifted SPWM technology is adopted in the cascade inverter to reduce harmonious wave of output voltage and current, meanwhile, a new type of bypass control method is proposed to collect all the feedback energy and restore it into the energy feedback units. According to the simulation of a three-phase and five-unit cascaded inverter with three energy feedback units, the results demonstrate that the proposed inverter can be input near sinusoidal current , and realize two-way flow of energy automatically with simplified phase shifting transformer structure, and show its feasibility and effectiveness.
Comparison of Modulation Techniques for Multilevel Inverter fed Permanent Magnet Synchronous Motor
Directory of Open Access Journals (Sweden)
V. NAGA BHASKAR REDDY
2010-10-01
Full Text Available Multilevel inversion is a power conversion strategy in which the output voltage is obtained in steps thus bringing the output closer to a sine wave and reduces the Total Harmonic Distortion. Multilevel inverter structures have been developed to overcome shortcomings in solid-state switching device ratings so that they can be applied to higher voltage systems. In recent years, the multilevel inverters have drawn tremendous interest in the area of high-power medium-voltage energy control. Three different topologies have been proposed for multilevel inverters like Diode-Clamped Inverter, Capacitor Clamped Inverter and Cascaded Multi cell Inverter. In addition, several modulation and control strategies have been developed or adopted for multilevel inverters including the following multilevel Sinusoidal Pulse Width Modulation (SPWM, and Space Vector Modulation. In this paper, simulation of various modulating techniques i.e., Pulse Width Modulate techniques such as Sinusoidal PWM, Trapezoidal PWM, Stepped PWM, Stair case PWM, third harmonicinjected PWM, Modified SVPWM are applied for both Diode Clamped Three-Level Inverter and Diode Clamped Five-Level Inverter, and Space Vector PWM technique are analyzed for DC3LI. The best modulationtechnique are extended to Permanent Magnet Synchronous Motor.
Enhanced Buck–Boost Neutral-Point-Clamped Inverters With Simple Capacitive-Voltage Balancing
DEFF Research Database (Denmark)
Tan, Kuan Khoon; Gao, Feng; Loh, Poh Chiang
2010-01-01
In traditional neutral-point-clamped (NPC) inverters, two major operating issues encountered are their relatively limited voltage-buck variation range and capacitive-voltage imbalance, which can cause low-order harmonics to appear at the inverter output. Various methodologies have so far been...... been investigated in the context of buck–boost energy conversion, even though relevant techniques for traditional NPC inverters do exist but are generally overburdened by the accompanied switching loss increase and more complex control and hardware circuitries. To address these two topological concerns...... simultaneously, two new buck–boost NPC inverters with simple capacitive-voltage-balancing capability are proposed. Both inverters are demonstrated to exhibit a doubling of voltage gain, with one of them also shown to produce a better output waveform quality. Simulation and experimental results are provided...
A 6-switch single-phase 5-level current-source inverter
Institute of Scientific and Technical Information of China (English)
BAO Jian-yu; LI Yu-ling; ZHANG Zhong-chao
2006-01-01
The new 6-switch single-phase 5-level current-source inverter proposed in this paper was developed by properly simplifying the traditional 8-switch single-phase 5-level current-source inverter, and its operational principle was analyzed. Just like the problem of voltage-unbalance between different levels existing in voltage-source multilevel inverters, a similar problem of current-unbalance between different levels whether for the 8-switch single-phase 5-level current-source inverter, or for the new 6-switch 5-level current-source inverter also exists. A simple current-balance control method via DC current feedback is presented here to implement the current-balance control between different levels. And to reduce the output current harmonics, PWM control technique was used. Simulation and experimental results showed that this new 6-switch topology operates correctly and that the balance-inductor can almost equally distribute the total DC current.
DEFF Research Database (Denmark)
Sanjeevikumar, Padmanaban; Grandi, Gabriele; Wheeler, Patrick
2015-01-01
This paper presents the novel topology of Photo Voltaic (PV) power generation system with simple Maximum Power Point Tracking (MPPT) algorithm in voltage operating mode. Power circuit consists of high output voltage DC-DC boost converter which maximizes the output of PV panel. Usually traditional...... of DC-DC converters for PV integration. Hence, to overcome these difficulties this paper investigates a DC-DC boost converter together with the additional parasitic component within the circuit to provide high output voltages for maximizing the PV power generation. The proposed power system circuit...... substantially improves the high output-voltage by a simple MPPT closed loop proportional-integral (P-I) controller, and requires only two sensor for feedback needs. The complete numerical model of the converter circuit along with PV MPPT algorithm is developed in numerical simulation (Matlab/Simulink) software...
Directory of Open Access Journals (Sweden)
Carter Craig E.
2017-01-01
Full Text Available Australia and most other countries are adopting renewable energy generation as the dominant means of reducing dependence on fossil fuels. This has been made more feasible by the exponential take-up of solar photovoltaic (PV systems and their concurrent production scale-up and cost decline. Rooftop solar PV, combined with battery storage, seems likely to be the dominant means of providing household electricity needs. In response to the technical challenges from rooftop PV, network utilities have implemented various low cost options to cope with PV’s impact on network voltages. However, if we want this clean energy technology to fully utilise the available roof space and eventually meet residential electricity needs, additional hardware, control and commercial options will need to be adopted by both network utilities and their customers to overcome the technical barriers, especially voltage rise. This paper presents the authors’ evaluations of options to mitigate voltage rise, including operating solar inverters with reactive power absorption (var absorbing, dependent only on solar power output or operating the solar inverters in a volt–var response mode (voltage droop control where the inverter adjusts its reactive power (Q in response to changes in its terminal voltage – Q(V. This paper also considers the fulltime Q(V option, where an inverter’s reactive power capacity is independent of solar conditions – statcom mode. The network utility option of using line drop compensation (LDC – used on long rural MV feeders on urban MV feeders during daylight hours is assessed to lessen voltage rise on LV feeders with low net loading or reverse power flow due to high solar PV generation. The paper concludes that a combination of solar inverters performing fast fulltime voltage droop control outside a voltage deadband (statcom mode and HV/MV substation transformers with slow acting daytime LDC mitigates voltage rise, whilst limiting feeder
Directory of Open Access Journals (Sweden)
MOALLEMI KHIAVI, A.
2015-08-01
Full Text Available Nowadays power converters play an important role in power system and industrial centers. One of the most important and widely used types of conversion is DC to AC conversion that is also called inverters. Generally inverters are divided to voltage source inverter (VSI and current source inverter (CSI. From another view the inverters are divided to two-level and multilevel types. The multilevel inverters are attractive because of their good output waveform quality. However, there has been less attention to multilevel current source inverter (MLCSI when compared with multilevel VSI. In this paper, a new topology for MLCSI is proposed. The proposed topology employs reduced number of switches to generate desired multilevel output current. The proposed MLCSI is capable of balancing the currents of the inductors that are used in the MLCSI structure. A multicarrier PWM based switching strategy is also proposed for the MLCSI. The simulation results using PSCAD/EMTDC as well as the experimental results from a single-phase 5-level CSI laboratory prototype demonstrate its validity.
DEFF Research Database (Denmark)
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2014-01-01
Grid-connected photovoltaic (PV) inverters tailored with reactive power management feature can support the grid voltage especially when the voltage fluctuates near its admissible limits. Although Q control allows reducing the grid voltage elevation along the distribution feeder, it brings extra...
Oliver, Bob; Pawałowski, Krzystof
1991-01-01
As part of the scientific activity in connection with the 70th birthday of the Adam Mickiewicz University in Poznan, an international conference on algebraic topology was held. In the resulting proceedings volume, the emphasis is on substantial survey papers, some presented at the conference, some written subsequently.
Frank-Kamenetskii, Maxim D.
2013-01-01
A new variety on non-coding RNA has been discovered by several groups: circular RNA (circRNA). This discovery raises intriguing questions about the possibility of the existence of knotted RNA molecules and the existence of a new class of enzymes changing RNA topology, RNA topoisomerases.
Digital power factor control and reactive power regulation for grid-connected photovoltaic inverter
Energy Technology Data Exchange (ETDEWEB)
Hassaine, L. [Power Electronics Systems Group, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain); Ecole Nationale Polytechnique, Hassen Badi, El Harrach, Alger (Algeria); Olias, E.; Quintero, J. [Power Electronics Systems Group, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain); Haddadi, M. [Ecole Nationale Polytechnique, Hassen Badi, El Harrach, Alger (Algeria)
2009-01-15
The overall efficiency of photovoltaic (PV) systems connected to the grid depends on the efficiency of direct current (DC) of the solar modules to alternate current (AC) inverter conversion. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, high power factor and low total harmonic distortion of the currents injected into the grid. An approach to power factor control and reactive power regulation for PV systems connected to the grid using field programmable gate array (FPGA) is proposed. According to the grid demands; both the injected active and reactive powers are controlled. In this paper, a new digital control strategy for a single-phase inverter is carried out. This control strategy is based on the phase shift between the inverter output voltage and the grid voltage, and the digital sinusoidal pulse width modulation (DSPWM) patterns, in order to control the power factor for a wide range of the inverter output current and consequently the control and the regulation of the reactive power will be achieved. The advantage of the proposed control strategy is its implementation around simple digital circuits. In this work, a simulation study of this strategy has been realized using Matlab/Simulink and PSIM. In order to validate its performance, this control has been implemented in a FPGA. Experimental tests have been carried out demonstrating the viability of this control in order to control the power factor and the injected power into the grid. (author)
Flexible packaging for PV modules
Dhere, Neelkanth G.
2008-08-01
Economic, flexible packages that provide needed level of protection to organic and some other PV cells over >25-years have not yet been developed. However, flexible packaging is essential in niche large-scale applications. Typical configuration used in flexible photovoltaic (PV) module packaging is transparent frontsheet/encapsulant/PV cells/flexible substrate. Besides flexibility of various components, the solder bonds should also be flexible and resistant to fatigue due to cyclic loading. Flexible front sheets should provide optical transparency, mechanical protection, scratch resistance, dielectric isolation, water resistance, UV stability and adhesion to encapsulant. Examples are Tefzel, Tedlar and Silicone. Dirt can get embedded in soft layers such as silicone and obscure light. Water vapor transmittance rate (WVTR) of polymer films used in the food packaging industry as moisture barriers are ~0.05 g/(m2.day) under ambient conditions. In comparison, light emitting diodes employ packaging components that have WVTR of ~10-6 g/(m2.day). WVTR of polymer sheets can be improved by coating them with dense inorganic/organic multilayers. Ethylene vinyl acetate, an amorphous copolymer used predominantly by the PV industry has very high O2 and H2O diffusivity. Quaternary carbon chains (such as acetate) in a polymer lead to cleavage and loss of adhesional strength at relatively low exposures. Reactivity of PV module components increases in presence of O2 and H2O. Adhesional strength degrades due to the breakdown of structure of polymer by reactive, free radicals formed by high-energy radiation. Free radical formation in polymers is reduced when the aromatic rings are attached at regular intervals. This paper will review flexible packaging for PV modules.
Comparison of Pyranometers vs. PV Reference Cells for Evaluation of PV Array Performance
Energy Technology Data Exchange (ETDEWEB)
Dunn, L.; Gostein, M.; Emery, K.
2012-09-01
As the photovoltaics (PV) industry has grown, the need for accurately monitoring the solar resource of PV power plants has increased. Historically, the PV industry has relied on thermopile pyranometers for irradiance measurements, and a large body of historical irradiance data taken with pyranometers exists. However, interest in PV reference devices is increasing. In this paper, we discuss why PV reference devices are better suited for PV applications, and estimate the typical uncertainties in irradiance measurements made with both pyranometers and PV reference devices. We assert that the quantity of interest in monitoring a PV power plant is the equivalent irradiance under the IEC 60904-3 reference solar spectrum that would produce the same electrical response in the PV array as the incident solar radiation. For PV-plant monitoring applications, we find the uncertainties in irradiance measurements of this type to be on the order of +/-5% for thermopile pyranometers and +/-2.4% for PV reference devices.
Efficient Control of Energy Storage for Increasing the PV Hosting Capacity of LV Grids
DEFF Research Database (Denmark)
Hashemi Toghroljerdi, Seyedmostafa; Østergaard, Jacob
2016-01-01
hosting capacity of LV grids by determining dynamic set points for EESS management. The method has the effectiveness of central control methods and can effectively decrease the energy storage required for overvoltage prevention, yet it eliminates the need for a broadband and fast communication. The net...... power injected into the grid and the amount of reactive power absorbed by PV inverters are estimated using the PV generation forecast and load consumption forecast, and the dynamic operating points for energy storage management are determined for a specific period of time by solving a linear...... grid is usually limited by overvoltage, and the efficient control of distributed electrical energy storage systems (EESSs) can considerably increase this capacity. In this paper, a new control approach based on the voltage sensitivity analysis is proposed to prevent overvoltage and increase the PV...
Grid-connected Photovoltaic Micro-inverter with New Hybrid Control LLC Resonant Converter
DEFF Research Database (Denmark)
Xingkui, Mao; Qisheng, Huang; Qingbo, Ke;
2016-01-01
A high-efficiency photovoltaic (PV) micro-inverter consisting of two power stages i.e. a LLC resonant converter with a new hybrid control scheme and a dc-ac inverter is proposed, studied and designed in this paper. In the first power stage, the new hybrid control combining pulse...... power of 250W and output voltage of 220VAC/50Hz. The experiment shows that the peak efficiency of the PVMI is 95.5%, where efficiency of LLC converter is up to 97.7%, and the MPPT accuracy is more than 99%. Thus the validity of the proposed system structure, design and control method is verified....
Control of Hybrid System Using Multi-Input Inverter and Maximum Power Point Tracking
Directory of Open Access Journals (Sweden)
N.Sivakumar
2013-07-01
Full Text Available The objective of this paper is to control the Wind/PV hybrid system using Multi-input inverter to get constant output power for different operating conditions. The MPPT also used in this system to get the maximum peak power to the load. The perturbation observation (P&O method is used to accomplish the maximum power point tracking algorithm for input sources. The operating principle of the open loop and closed loop circuit of multi-input inverter is discussed.
Solar PV. Innovators talking; Zon PV. Innovators aan het woord
Energy Technology Data Exchange (ETDEWEB)
NONE
2013-02-15
Qualitative studies have been conducted of the results of completed projects focused on energy innovation, spread over the seven themes of the top sector Energy: Energy saving in industry, Energy conservation in the built environment, Gas, Bio-energy, Smart grids, Offshore Wind, Solar PV. This provides insight into the follow-up activities and lessons of some EOS (Energy Research Subsidy) completed projects with the aim to inspire, connect and strengthen the TKIs (Topconsortia for Knowledge and Innovation) and individual companies and researchers working on energy innovation. This report concerns the research on solar PV [Dutch] Er is een kwalitatief onderzoek uitgevoerd naar de resultaten van afgeronde projecten gericht op energie-innovatie, verdeeld over de zeven thema's van de topsector Energie: Energiebesparing in de industrie; Energiebesparing in de gebouwde omgeving; Gas; Bio-energie; Smart grids; Wind op zee; Zon-pv. Daarmee wordt inzicht gegeven in de vervolgactiviteiten en lessen van een aantal afgesloten EOS-projecten (Energie Onderzoek Subsidie) met het oog op het inspireren, verbinden en versterken van de TKI's (Topconsortia voor Kennis en Innovatie) en individuele bedrijven en onderzoekers die werken aan energie-innovatie. Dit rapport betreft het onderzoek naar zon PV.
Luiijf, H.A.M.
2008-01-01
Organisaties die het Internet Protocol(IP) gebruiken voor beveiligingsdoeleinden en aanbieders van beveiligingsproducten ontkomen de komende jaren niet aan de overgang naar het nieuwe protocol lPv6. Enerzijds is het gelukkig dat die overgang niet op één dag wereldwijd zal plaatsvinden, er is geen 'I
Leakage Current Suppression with A Novel Six-Switch Photovoltaic Grid-Connected Inverter
DEFF Research Database (Denmark)
Wei, Baoze; Guo, Xiaoqiang; Guerrero, Josep M.;
2015-01-01
In order to solve the problem of the leakage current in non-isolated photovoltaic (PV) systems, a novel six-switch topology and control strategy are proposed in this paper. The inductor-bypass strategy solves the common-mode voltage limitation of the conventional six-switch topology in case...... of unmatched inductances. And the stray capacitor voltage of the non-isolated photovoltaic system is free of high frequency ripples. Theoretical analysis and simulation are carried out to verify the proposed topology and its control strategy. Results indicate that the leakage current suppression can...
Simulation of inverter dominated minigrids
Energy Technology Data Exchange (ETDEWEB)
Engler, A.; Osika, O. [Inst. fuer Solare Energieversorgungstechnik (ISET) e.V., Kassel (Germany)
2003-07-01
In order to assess the load flow, the transient behaviour and the stability of inverter dominated minigrids, a model for inverters and a transmission system has been developed. The inverters are represented by a frequency and voltage controlled three phase voltage source and the transmission systems consists of switches, overhead lines ({pi}-equivalent), transformers and a load. The inverters operate in parallel via the MV-distribution system and supply an active load. The contribution of each inverter is determined by the setting of the applied droops (similar to conventional power plants). Furthermore an approach for stability assessment of such systems is introduced. This research work is related to the EC-funded project MicroGrids. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Van Sark, W. [Sark Solar Energy Consultancy, Utrecht (Netherlands); Muizebelt, P. [New Energy Works, Utrecht (Netherlands); Cace, J. [Renewable Energy Company RenCom, Ouderkerk aan de Amstel (Netherlands)
2012-05-15
This report describes the results of an inventory of PV modules, inverters and system components that are available on the Dutch market. This inventory was conducted to feed the market with independent information and knowledge on available PV systems. The inventory was held in April 2012 as a follow-up to the inventory of October 2011 [Dutch] Dit rapport beschrijft de resultaten van een inventarisatie van PV modules, omvormers en systeemcomponenten die op de Nederlandse markt verkrijgbaar zijn. Deze inventarisatie is uitgevoerd om de markt te voeden met onafhankelijke informatie en kennis over beschikbare PV-systemen. De inventarisatie heeft plaatsgevonden in de maand april 2012 en is een vervolg op de inventarisatie van oktober 2011.
Energy Technology Data Exchange (ETDEWEB)
Van Sark, W. [Sark Solar Energy Consultancy, Utrecht (Netherlands); Muizebelt, P. [New Energy Works, Utrecht (Netherlands); Cace, J. [Renewable Energy Company RenCom, Ouderkerk aan de Amstel (Netherlands)
2012-08-15
This report describes the results of an inventory of PV modules, inverters and system components that are available on the Dutch market. This inventory was conducted to feed the market with independent information and knowledge on available PV systems. The inventory was held in April 2012 as a follow-up to the inventory of October 2011 and April 2012 [Dutch] Dit rapport beschrijft de resultaten van een inventarisatie van PV modules, omvormers en systeemcomponenten die op de Nederlandse markt verkrijgbaar zijn. Deze inventarisatie is uitgevoerd om de markt te voeden met onafhankelijke informatie en kennis over beschikbare PV-systemen. De inventarisatie heeft plaatsgevonden in de maand augustus 2012 en is een vervolg op de inventarisaties van april 2012 en oktober 2011.
Godoy Simões, Marcelo; Davi Curi Busarello, Tiago; Saad Bubshait, Abdullah; Harirchi, Farnaz; Antenor Pomilio, José; Blaabjerg, Frede
2016-04-01
This paper presents interactive smart battery-based storage (BBS) for wind generator (WG) and photovoltaic (PV) systems. The BBS is composed of an asymmetric cascaded H-bridge multilevel inverter (ACMI) with staircase modulation. The structure is parallel to the WG and PV systems, allowing the ACMI to have a reduction in power losses compared to the usual solution for storage connected at the DC-link of the converter for WG or PV systems. Moreover, the BBS is embedded with a decision algorithm running real-time energy costs, plus a battery state-of-charge manager and power quality capabilities, making the described system in this paper very interactive, smart and multifunctional. The paper describes how BBS interacts with the WG and PV and how its performance is improved. Experimental results are presented showing the efficacy of this BBS for renewable energy applications.
Analysis on Design of Grid-connected PV System%并网光伏系统设计简析
Institute of Scientific and Technical Information of China (English)
罗刚; 俞晟
2014-01-01
简要介绍常见并网光伏系统设计依据、常用软件、组成部分及其原理，以及光设计中需要把握的原则、注意事项和一些经验教训，包括光伏支架、光伏方阵与场地的设计考虑，并网逆变器的选择、并网形式的选择、防雷接地等。%The paper provides a brief introduction of the design basis, common software, components and principles of common grid-connected PV system, as well as principles, considerations and some experiences in PV design, including the design considerations of PV stent, PV array and venue, selection of grid-connected inverter and form and grounding for protection against lightning.
DEFF Research Database (Denmark)
Spataru, Sergiu; Sera, Dezso; Hacke, Peter
2014-01-01
Photovoltaic system (PV) maintenance and diagnostic tools are often based on performance models of the system, complemented with light current-voltage (I-V) measurements, visual inspection and/or thermal imaging. Although these are invaluable tools in diagnosing PV system performance losses...... or contacts are damaged/degraded). With the recent growth and development of new module level dc-dc optimizers and micro inverters, capable of bidirectional current flow, it is now possible to implement both dark I-V and light I-V measurements as complementary diagnostic tools. By complementing light I-V...... measurements, which reflect both the optical and electrical performance parameters of the PV device, with dark I-V measurements, which focus only on the electrical characteristic of the PV device, the optical factors determining power loss (such as partial shadows, soiling, discoloration of the plastic...
Energy Technology Data Exchange (ETDEWEB)
Gounden, N. Ammasai; Ann Peter, Sabitha; Nallandula, Himaja; Krithiga, S. [Department of Electrical and Electronics Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu (India)
2009-03-15
A fuzzy logic controller has been developed for interfacing PV array with utility grid through a three-phase line-commutated inverter for the first time. The controller tracks and feeds maximum power to the utility grid. The linguistic variables have been selected appropriately to modulate the firing angle of the inverter for tracking the maximum power. The simulink model of the proposed scheme employing fuzzy logic controller has been built using MATLAB/PSB. A PIC microcontroller has been programmed for generation of firing pulses to the thyristors in the inverter. Experimental setup of the proposed scheme has been built and the results obtained on a PV array of 54 V, 12 A rating are presented. The comparison of experimental and simulation results shows very close agreement between the two thus validating the controller proposed. (author)
Progress & Frontiers in PV Performance
Energy Technology Data Exchange (ETDEWEB)
Deline, Chris; DiOrio, Nick; Jordan, Dirk; Toor, Fatima
2016-09-12
PowerPoint slides for a presentation given at Solar Power International 2016. Presentation includes System Advisor Model (SAM) introduction and battery modeling, bifacial PV modules and modeling, shade modeling and module level power electronics (MLPE), degradation rates, and PVWatts updates and validation.
Energy Technology Data Exchange (ETDEWEB)
Becker, Daniela
2011-07-01
As a result of the Green Energy Act, the installed PV capacity in the Canadian province of Ontario has tripled in the year 2010. A generous feed-in tariff, aiming at maximum local added value, has attracted numerous international manufacturers. However, the rigorous rules committing the companies to 60 % inland production have provoked harsh criticism. (orig.)
Design and Analysis of an Improved MPPT for Photovoltaic Grid-Connected Inverter Based
Directory of Open Access Journals (Sweden)
Meysam Bayat
2015-03-01
Full Text Available One of the major drawbacks of photovoltaic (PV systems is represented by the effect of module mismatching and of partial shading of the PV ﬁeld. This paper proposes a method of maximum power point tracking using Quantum behaved particle swarm optimization (QPSO for grid-connected photovoltaic systems. The system is composed of a boost converter and a Single-phase inverter connected to a utility grid. The maximum power point tracking control is based on Proposed control a switch of a boost converter. QPSO controllers provide attractive features such as fast response, good performance. The Single phase inverter uses predictive current control which provides current with sinusoidal waveform. Therefore, the system is able to deliver energy with low harmonics and high power factor. From the simulation results, the adaptive QPSO controller can deliver more power than the conventional controller.
Institute of Scientific and Technical Information of China (English)
胡克用; 胥芳; 艾青林; 徐红伟; 欧阳静
2016-01-01
针对自然环境中阴雨天会大大降低光伏面板的发电量，使得光伏阵列的输出功率与逆变器额定功率无法匹配，从而引起光伏发电系统总功率大幅下降的问题，采用分布式光伏阵列及逆变器的群控方法，通过开关矩阵将光伏阵列与逆变器相连，形成分布式光伏阵列及逆变器拓扑网络结构，并详细阐述了该拓扑网络结构的工作原理与工作机制。研究了该网络的群控系统，并提出相应的自适应聚类算法，实现多逆变器光伏发电网络的群控管理。最后对整个网络结构系统进行了仿真分析及试验验证，结果表明，在不利于光伏发电的恶劣天气条件中，该控制策略可对不同逆变器的输入功率进行优化匹配，从而提高整个光伏发电系统的发电效率。%The power generation of photovoltaic panels is greatly reduced during the cloudy and rainy days in natural environment,the output power of PV array and the rated power of inverter can not be matched,and it will cause the total power of photovoltaic system decrease sharply.This thesis adopted distributed photovoltaic array and group control method of the inverters.The photovoltaic array and the inverters were connected by the switch matrix,and formed a distributed topology network structure of photovoltaic array and inverters.While,it described the working principle and working mechanism of the network topology structure.At the same time it analyzed the constraint con-ditions of electrical parameters from the point of mathematics.Study on the group control of the network,in order to cope with such topology,it put forward the corresponding adaptive clustering algorithm to realize the switching control of matrix and optimize the structure of PV array,thus fulfill the group control management of multi-inverters photovoltaic power network.The whole network structure of the system was validated by the simulation and experiment;the results
Fomenko, Anatoly
2016-01-01
This classic text of the renowned Moscow mathematical school equips the aspiring mathematician with a solid grounding in the core of topology, from a homotopical perspective. Its comprehensiveness and depth of treatment are unmatched among topology textbooks: in addition to covering the basics—the fundamental notions and constructions of homotopy theory, covering spaces and the fundamental group, CW complexes, homology and cohomology, homological algebra—the book treats essential advanced topics, such as obstruction theory, characteristic classes, Steenrod squares, K-theory and cobordism theory, and, with distinctive thoroughness and lucidity, spectral sequences. The organization of the material around the major achievements of the golden era of topology—the Adams conjecture, Bott periodicity, the Hirzebruch–Riemann–Roch theorem, the Atiyah–Singer index theorem, to name a few—paints a clear picture of the canon of the subject. Grassmannians, loop spaces, and classical groups play a central role ...
The case for better PV forecasting
DEFF Research Database (Denmark)
Alet, Pierre-Jean; Efthymiou, Venizelos; Graditi, Giorgio
2016-01-01
Rising levels of PV penetration mean increasingly sophisticated forecasting technologies are needed to maintain grid stability and maximise the economic value of PV systems. The Grid Integration working group of the European Technology and Innovation Platform – Photovoltaics (ETIP PV) shares...... the results of its ongoing research into the advantages and limitations of current forecasting technologies....
Bull, Carolee T; Clarke, Christopher R; Cai, Rongman; Vinatzer, Boris A; Jardini, Teresa M; Koike, Steven T
2011-07-01
Since 2002, severe leaf spotting on parsley (Petroselinum crispum) has occurred in Monterey County, CA. Either of two different pathovars of Pseudomonas syringae sensu lato were isolated from diseased leaves from eight distinct outbreaks and once from the same outbreak. Fragment analysis of DNA amplified between repetitive sequence polymerase chain reaction; 16S rDNA sequence analysis; and biochemical, physiological, and host range tests identified the pathogens as Pseudomonas syringae pv. apii and P. syringae pv. coriandricola. Koch's postulates were completed for the isolates from parsley, and host range tests with parsley isolates and pathotype strains demonstrated that P. syringae pv. apii and P. syringae pv. coriandricola cause leaf spot diseases on parsley, celery, and coriander or cilantro. In a multilocus sequence typing (MLST) approach, four housekeeping gene fragments were sequenced from 10 strains isolated from parsley and 56 pathotype strains of P. syringae. Allele sequences were uploaded to the Plant-Associated Microbes Database and a phylogenetic tree was built based on concatenated sequences. Tree topology directly corresponded to P. syringae genomospecies and P. syringae pv. apii was allocated appropriately to genomospecies 3. This is the first demonstration that MLST can accurately allocate new pathogens directly to P. syringae sensu lato genomospecies. According to MLST, P. syringae pv. coriandricola is a member of genomospecies 9, P. cannabina. In a blind test, both P. syringae pv. coriandricola and P. syringae pv. apii isolates from parsley were correctly identified to pathovar. In both cases, MLST described diversity within each pathovar that was previously unknown.
Modulation of Current Source Inverter
Directory of Open Access Journals (Sweden)
Golam Reza Arab Markadeh
2011-04-01
Full Text Available Direct torque control with Current Source Inverter (CSI instead of voltage source inverter is so appropriate because of determining the torque of induction motor with machine current and air gap flux. In addition, Space-Vector Modulation (SVM is a more proper method for CSI because of low order harmonics reduction, lower switching frequency and easier implementation. This paper introduces the SVM method for CSI and uses the proposed inverter for vector control of an induction motor. The simulation results illustrate fast dynamic response and desirable torque and speed output. Fast and accurate response to changes of speed and load torque reference completely proves the prominence of this method.
Grid Integrated Distributed PV (GridPV) Version 2.
Energy Technology Data Exchange (ETDEWEB)
Reno, Matthew J.; Coogan, Kyle
2014-12-01
This manual provides the documentation of the MATLAB toolbox of functions for using OpenDSS to simulate the impact of solar energy on the distribution system. The majority of the functio ns are useful for interfacing OpenDSS and MATLAB, and they are of generic use for commanding OpenDSS from MATLAB and retrieving information from simulations. A set of functions is also included for modeling PV plant output and setting up the PV plant in th e OpenDSS simulation. The toolbox contains functions for modeling the OpenDSS distribution feeder on satellite images with GPS coordinates. Finally, example simulations functions are included to show potential uses of the toolbox functions. Each function i n the toolbox is documented with the function use syntax, full description, function input list, function output list, example use, and example output.
Transient Monitoring Function–Based Fault Detection for Inverter-Interfaced Microgrids
DEFF Research Database (Denmark)
Sadeghkhani, Iman; Esmail Hamedani Golshan, Mohamad; Mehrizi-Sani, Ali;
2017-01-01
conditions from normal load switching events and is effective for various inverter topologies (i.e., three/four-leg), main current limiting strategies, and all reference frames of the multi-loop control system. The merits of the proposed fault detection scheme are demonstrated through several time...
Analyze and Improve Lifetime in 3L-NPC Inverter from Power Cycle and Thermal Balance
DEFF Research Database (Denmark)
Chen, Quan; Chen, Zhe; Wang, Qunjing
2014-01-01
Three-level Neutral-point-clamped (3L-NPC) topology is becoming a realistic alternative to the conventional one in high-voltage and high-power application. Studies show that the power cycling mean time to failure (MTTF) of the semiconductor bond wire in 3L-NPC inverter system may be very short un...
The PWM strategies of grid-connected distributed generation active NPC inverters
DEFF Research Database (Denmark)
Ma, Lin; Xinmin, Jin; Kerekes, Tamas
2009-01-01
The Neutral Point Clamped topology due to high efficiency, low leakage current and EMI, its integration is widely used in the distributed generation (DG) systems. However the main disadvantage of the NPC inverter is given by an unequal distribution of the losses in the semiconductor devices, which...... leads to an unequal distribution of temperature. By using the Active NPC topology, the power losses distribution problem is alleviated. The modulation strategy is a key issue for losses distribution in this topology. In this paper two known strategies are discussed and a new proposed PWM strategy...
Resurrection of An Inverted Pendulum
Kim, S Y; Kim, Sang-Yoon; Hu, Bambi
1998-01-01
We study the bifurcations associated with stability of the inverted (stationary) state in the parametrically forced pendulum by varying the driving amplitude $\\epsilon$ and frequency $\\omega$. We first note that the inverted state is unstable for $\\epsilon=0$. However, as $\\epsilon$ is increased, the inverted state exhibits a cascade of ``resurrections,'' i.e., it becomes stabilized after its instability, destabilize again, and so forth ad infinitum for any given $\\omega$. Its stabilizations (destabilizations) occur via alternating subcritical (supercritical) pitchfork and period-doubling bifurcations. An infinite sequence of period-doubling bifurcations, leading to chaos, also follows each destabilization of the inverted state. The critical behaviors in the period-doubling cascades are also discussed.
Guillemin, Victor
2010-01-01
Differential Topology provides an elementary and intuitive introduction to the study of smooth manifolds. In the years since its first publication, Guillemin and Pollack's book has become a standard text on the subject. It is a jewel of mathematical exposition, judiciously picking exactly the right mixture of detail and generality to display the richness within. The text is mostly self-contained, requiring only undergraduate analysis and linear algebra. By relying on a unifying idea-transversality-the authors are able to avoid the use of big machinery or ad hoc techniques to establish the main
Power Quality Improvement Wind Energy System Using Cascaded Multilevel Inverter
Directory of Open Access Journals (Sweden)
J.S. Sathiyanarayanan
2013-02-01
Full Text Available In this paper, a wind energy conversion system based on a cascaded H-bridgemultilevel inverter (CHBMLI topology has been proposed to be used for the grid interface of largesplit winding alternators (SWAs. A new method has been suggested for the generation of referencecurrents for the voltage source inverter (VSI depending upon the available wind power. TheCHBMLI has been used as a VSI and operated in a current control mode order to achieve theobjectives of real power injection and load compensation (power factor correction, load balancing,and harmonic compensation based on the proposed reference generation scheme. In the fieldexcitation control of SWA provides a single means vary the dc link voltages of all the CHBssimultaneously and proportionately.
Energy Technology Data Exchange (ETDEWEB)
Ozdemir, Engin [ORNL; Ozdemir, Sule [Oak Ridge National Laboratory (ORNL); Tolbert, Leon M [ORNL
2009-01-01
This paper presents a fundamental-frequency-modulated diode-clamped multilevel inverter (DCMLI) scheme for a three-phase stand-alone photovoltaic (PV) system. The system consists of five series-connected PV modules, a six-level DCMLI generating fundamental-modulation staircase three-phase output voltages, and a three-phase induction motor as the load. In order to validate the proposed concept, simulation studies and experimental measurements using a small-scale laboratory prototype are also presented. The results show the feasibility of the fundamental frequency switching application in three-phase stand-alone PV power systems.
Advanced Grid-Friendly Controls Demonstration Project for Utility-Scale PV Power Plants
Energy Technology Data Exchange (ETDEWEB)
Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); O' Neill, Barbara [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2016-01-21
A typical photovoltaic (PV) power plant consists of multiple power electronic inverters and can contribute to grid stability and reliability through sophisticated 'grid-friendly' controls. The availability and dissemination of actual test data showing the viability of advanced utility-scale PV controls among all industry stakeholders can leverage PV's value from being simply an energy resource to providing additional ancillary services that range from variability smoothing and frequency regulation to power quality. Strategically partnering with a selected utility and/or PV power plant operator is a key condition for a successful demonstration project. The U.S. Department of Energy's (DOE's) Solar Energy Technologies Office selected the National Renewable Energy Laboratory (NREL) to be a principal investigator in a two-year project with goals to (1) identify a potential partner(s), (2) develop a detailed scope of work and test plan for a field project to demonstrate the gird-friendly capabilities of utility-scale PV power plants, (3) facilitate conducting actual demonstration tests, and (4) disseminate test results among industry stakeholders via a joint NREL/DOE publication and participation in relevant technical conferences. The project implementation took place in FY 2014 and FY 2015. In FY14, NREL established collaborations with AES and First Solar Electric, LLC, to conduct demonstration testing on their utility-scale PV power plants in Puerto Rico and Texas, respectively, and developed test plans for each partner. Both Puerto Rico Electric Power Authority and the Electric Reliability Council of Texas expressed interest in this project because of the importance of such advanced controls for the reliable operation of their power systems under high penetration levels of variable renewable generation. During FY15, testing was completed on both plants, and a large amount of test data was produced and analyzed that demonstrates the ability of
DEFF Research Database (Denmark)
Bhaskar, Mahajan Sagar; Padamanaban, Sanjeevi Kumar; Blaabjerg, Frede
2016-01-01
In this paper hybrid non isolated and non-invertingCockcroft-Walton multiplier based 2Nx InterleavedBoost converter (2Nx IBC) for renewable energy applications is presented. The presented hybrid boost converter topology is derived from non-inverting Nx Multilevel Boost Converter (Nx MBC......) and inverting Nx Multilevel Boost Converter (Nx MBC). In renewable energy applications, generated voltage needs to be stepped up with high conversion ratio using a DC-DC converter at voltage levels as per the application requirement. The advantages of the presentedtopology of interleaved converter are high...... voltage conversion ratio, reduce ripple, low voltage stress, non-inverting output voltage without utilizing the high duty cycle, coupled inductors and transformer. The main advantage of presented topology consists in increasing voltage gain by adding capacitor and diode into circuitry without disturbing...
Some topological properties of the Inverse Lens Mapping
Energy Technology Data Exchange (ETDEWEB)
Mediavilla, T; Ariza, O [Departamento de Estadistica e Investigacion Operativa, Universidad de Cadiz, Avda de Ramon Puyol, s/n 11202 Algeciras (Spain); Mediavilla, E; Oscoz, A [Instituto de Astrofisica de Canarias, Avda Via Lactea s/n, La Laguna (Spain); Munoz, J A, E-mail: teresa.mediavilla@ca.uca.es, E-mail: octavio.ariza@uca.es, E-mail: emg@iac.es, E-mail: jmunoz@uv.es, E-mail: aoscoz@iac.es [Departamento de Astronomia y Astrofisica, Universidad de Valencia, c/ Dr. Moliner, 50, 46100 Burjassot (Spain)
2011-09-22
Away from critical curves, lens mapping can be seen as a linear invertible transformation of the plane even for regions (cells) of relatively large size. However, close to critical curves the departures from linearity can be very strong. We discuss the topological problems induced by the mapping of regions of the image plane that include critical curves (critical cells).
Topological algebras of rapidly decreasing matrices and generalizations
Glockner, Helge
2010-01-01
It is a folklore fact that the rapidly decreasing matrices of countable size form an associative topological algebra whose set of quasi-invertible elements is open, and such that the quasi-inversion map is continuous. We provide a direct proof, which applies more generally to a large class of algebras of weighted matrices with entries in a Banach algebra.
Stability Analysis for Isolated AC Microgrids Based on PV-Active Generators
DEFF Research Database (Denmark)
Aldana, Nelson Leonardo Diaz; Coelho, Ernane A. A.; Quintero, Juan Carlos Vasquez;
2015-01-01
The current trend in isolated microgrids is oriented to distributed renewable energy generators, such as photovoltaic (PV) generators and their corresponding distributed energy storage systems (ESS) as an unit denoted as active generator (PV+ESS). In an isolated microgrid, every distributed...... for all the distributed generators. In particular, ESS’s based on batteries require at least two different mode of charge. As consequence, the topological operation mode of the microgrid is affected by the changes of the operation mode of each distributed generator. Typically, droop control loops are used...... for interconnecting several different distributed generators in parallel to a common bus, whose parameters determine the stability and damping of the microgrid operation. In this paper, a small-signal stability analysis is applied to an isolated AC microgrid composed of (PV+ESS) active generators, regarding three...
Lv, Z. H.; Li, Q.; Huang, R. W.; Liu, H. M.; Liu, D.
2016-08-01
Based on the discussion about topology structure of integrated distributed photovoltaic (PV) power generation system and energy storage (ES) in single or mixed type, this paper focuses on analyzing grid-connected performance of integrated distributed photovoltaic and energy storage (PV-ES) systems, and proposes a comprehensive evaluation index system. Then a multi-level fuzzy comprehensive evaluation method based on grey correlation degree is proposed, and the calculations for weight matrix and fuzzy matrix are presented step by step. Finally, a distributed integrated PV-ES power generation system connected to a 380 V low voltage distribution network is taken as the example, and some suggestions are made based on the evaluation results.
Accelerating Development of Advanced Inverters.
Energy Technology Data Exchange (ETDEWEB)
Neely, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ropp, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-12-01
Increasing the penetration of distributed renewable sources, including photovoltaic (PV) generators, poses technical challenges for grid management. The grid has been optimized over decades to rely on large centralized power plants with well-established feedback controls. Conventional generators provide relatively constant dispatchable power and help to regulate both voltage and frequency. In contrast, photovoltaic (PV) power is variable, is only as predictable as the weather, and provides no control action. Thus, as conventional generation is displaced by PV power, utility operation stake holders are concerned about managing fluctuations in grid voltage and frequency. Furthermore, since the operation of these distributed resources are bound by certain rules that require they stop delivering power when measured voltage or frequency deviate from the nominal operating point, there are also concerns that a single grid event may cause a large fraction of generation to turn off, triggering a black out or break-up of an electric power system.
Directory of Open Access Journals (Sweden)
Abolfazl Kazemdehdashti
2013-01-01
Full Text Available In this paper, dynamic voltage restorer (DVR compensation methods are compared to each other for the load side connected shunt converter topology of z-source inverter based DVR to choose the best method. Four different topologies are recognized for DVR that two of them have energy storage devices, and two topologies have no energy storage that take ener\\-gy from the grid during the period of compensation. Here the load side connected shunt converter topology that takes necessary energy from the grid is used. Pre-sag compensation, in-phase compensation, energy-optimized methods are the three DVR compensation methods that studied and compared. A deep analysis through different diagrams would show the advantages or disadvantages of each compensation method. Equations for all methods are derived and the characteristics of algorithms are compared with each other. The simulation results done by SIMULINK/ MATLAB shows compensating by this topology based on the compensation methods.
Directory of Open Access Journals (Sweden)
UNLU, M.
2015-05-01
Full Text Available A simple power electronic interface based on the line-commutated inverter (LCI has been developed in order to inject sinusoidal current to the grid for single-phase grid-connected photovoltaic (PV energy generation systems. The proposed inverter facilitates controlling the injecting/grid current with a controllable power factor in contrast to the conventional LCI system. It is achieved that the total harmonic distortion (THD of the injecting currents for the different firing angles/power factors and reference currents is about 5% or less than 5%. Thus, the grid-connected standards for injecting current are satisfied without filter equipment unlike the conventional LCI system. The proposed system has been built in MATLAB/Simulink and examined experimentally on PV array of 160 W. The simulation and experimental results are better performance than the conventional line-commutated inverter methods reported in the literature. The proposed LCI has a simple and robust structure, and it can be easily synchronized with grid thanks to self-latching property of SCRs. Therefore, it is a good alternative for the power transferring from PV panels to the utility grid in grid-connected PV systems.
Γ-source Neutral Point Clamped Inverter
DEFF Research Database (Denmark)
Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede
Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....
Control Architecture for Parallel-Connected Inverters in Uninterruptible Power Systems
DEFF Research Database (Denmark)
Zhang, Chi; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez;
2016-01-01
that guarantees synchronization with an external real/fictitious utility, and critical bus voltage amplitude restoration. Improved transient and steady-state frequency, active, reactive and harmonic power sharing, and global phase-locked loop resynchronization capability are achieved. Detailed system topology...... bus. The proposed control scheme comprises two layers: (i) a local layer that contains a “reactive power-to-phase droop” in order to synchronize the phase angle of each inverter and a virtual resistance loop that guarantees equal power sharing among inverters; and (ii) a central controller......In this paper, a control strategy for the parallel operation of three-phase inverters forming an online uninterruptible power system (UPS) is presented. The UPS system consists of a cluster of paralleled inverters with LC filters directly connected to an AC critical bus and an AC/DC forming a DC...
DEFF Research Database (Denmark)
Sadeghkhani, Iman; Esmail Hamedani Golshan, Mohamad; Guerrero, Josep M.
2017-01-01
With high penetration of distributed energy resources (DER), fault management strategy is of great importance for the distribution network operation. The objective of this paper is to propose a current and voltage limiting strategy to enhance fault ride-through (FRT) capability of inverter......-based islanded microgrids (MGs) in which the effects of inverter control system and inverter topology (four/three-wire) are considered. A threephase voltage-sourced inverter (VSI) with multi-loop control system implemented in synchronous, stationary, and natural reference frames is employed in this study...... for both four- and three-wire configurations. The proposed strategy provides high voltage and current quality during overcurrent conditions, which is necessary for sensitive loads. Several time-domain simulation studies are conducted to investigate the FRT capability of the proposed strategy against both...