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1.
ABSTRACTThis paper presents a current source inverter (CSI)-based hybrid power generation system, which uses wind turbine and photovoltaic cells (PVs). A permanent magnet synchronous generator (PMSG) is connected to the CSI using a diode rectifier and a buck converter that is used to control the speed of the rotor. Another buck converter is used to control the maximum power point tracking of PVs. The operation of proposed system is studied under normal and grid voltage dip conditions. According to new grid codes, most power generating units are supposed to remain connected to the grid during voltage sag conditions and inject reactive current to grid as defined by grid codes. The CSI has fault current limiting capability that makes it appropriate to use in grid-connected applications and during voltage sag conditions in particular. The proposed system tracks the maximum power point of wind turbine and PVs under normal mode and injects required reactive current to the grid during voltage drop. However, incorporation of CSI with the inherent behaviour of wind turbine and PVs causes fault current to be within the tolerable range for power electronic devices. Simulations are carried out by using PSCAD/EMTDC software to verify the proposed system. 相似文献
2.
随着新能源发电的迅速发展,越来越多的可再生能源被转化为电能并通过并网逆变器输送到电网。利用MATLAB仿真工具箱建立了由光伏阵列输出、Boost升压电路、逆变器、控制器、电网等组成的5 kW光伏并网发电系统的仿真模型,研究了光伏并网系统的特性。采用变结构模糊PID控制器实现5 kW光伏发电系统的MPPT;采样电网电压作为逆变器电流的参考信号,利用滞环比较法控制逆变器,实现系统输出电流与电网电压同频同相,功率因素近似为1。仿真结果表明,系统较好地实现了光伏发电系统的MPPT及安全并网,对实际光伏并网系统的设计有参考意义。 相似文献
3.
Marco Liserre Frede Blaabjerg Antonio Dell’Aquila 《International Journal of Electronics》2013,100(8):445-460
The voltage source active rectifier is one of the most interesting solutions to interfacing dc power systems to the grid. Many elements are responsible for the overall system behaviour, such as value of the passive elements, sensors position, analog/digital filters and ac current/dc voltage controllers. In this paper a step-by-step design procedure, taking into account all these elements, is proposed and validated through the tests on an experimental prototype. The reported results are particularly relevant to evaluate the influence on the grid current harmonic content of the grid sensor position and of the use of analog filters in the feedback signals. 相似文献
4.
McGrath B.P. Holmes D.G. Galloway J.J.H. 《Power Electronics, IEEE Transactions on》2005,20(4):877-884
Line synchronization of grid connected power converters is a well recognized problem when the grid is weak, or derives from a remote area power supply with poor frequency regulation. Such systems can suffer significant line voltage distortion due to notches caused by power device switching and/or low frequency harmonic content, which can easily corrupt the output of a conventional zero crossing detector. This paper presents a method of filtering the incoming grid voltage using a recursive discrete Fourier transform (DFT). The filter provides a high degree of noise immunity but does produce a phase shift between the incoming grid voltage and the filtered output voltage when the DFT time window does not match the grid period. Two methods of compensating this phase shift are presented, based on tracking the drift in the phase predicted by the recursive DFT. The first method makes a deadbeat adjustment to the time window (thereby changing the sampling rate) while the second approach calculates the phase error based on the linear phase response of the DFT. These compensation algorithms can correct for discrepancies of at least 25% between the DFT time window and the system period, and can track grid frequencies with slew rates as high as 40 Hz/s with negligible phase shift (<2/spl deg/) between the grid voltage input and the filtered output waveforms. 相似文献
5.
An Improved Control Strategy of Limiting the DC-Link Voltage Fluctuation for a Doubly Fed Induction Wind Generator 总被引:2,自引:0,他引:2
Jun Yao Hui Li Yong Liao Zhe Chen 《Power Electronics, IEEE Transactions on》2008,23(3):1205-1213
The paper presents to develop a new control strategy of limiting the dc-link voltage fluctuation for a back-to-back pulsewidth modulation converter in a doubly fed induction generator (DFIG) for wind turbine systems. The reasons of dc-link voltage fluctuation are analyzed. An improved control strategy with the instantaneous rotor power feedback is proposed to limit the fluctuation range of the dc-link voltage. An experimental rig is set up to valid the proposed strategy, and the dynamic performances of the DFIG are compared with the traditional control method under a constant grid voltage. Furthermore, the capabilities of keeping the dc-link voltage stable are also compared in the ride-through control of DFIG during a three-phase grid fault, by using a developed 2 MW DFIG wind power system model. Both the experimental and simulation results have shown that the proposed control strategy is more effective, and the fluctuation of the dc-link voltage may be successfully limited in a small range under a constant grid voltage and a non-serious grid voltage dip. 相似文献
6.
Jalili K. Weitendorf N. Bernet S. 《Industrial Electronics, IEEE Transactions on》2008,55(3):1035-1046
This paper investigates the effects of grid voltage distortions caused by thyristor converters on the steady-state performance of a pulsewidth modulation (PWM) rectifier with dc voltage link for low-voltage applications. The disturbance transfer function of the current control loop is used to analyze the effects of grid distortions. Influences of the current controller, the phase-locked loop parameters, and the filter inductance on the generated current harmonics are presented. For existing grid voltage harmonics, the amplitude of the corresponding current harmonics are determined and compared to measured current harmonics using a 400-V 40-kW test bench consisting of a PWM rectifier with voltage dc link parallel to a 40-kW thyristor converter. 相似文献
7.
DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications 总被引:1,自引:0,他引:1
8.
风电机组运行过程中,由于电网故障等原因,会出现瞬时电压跌落现象。本文研发了低电压穿越(LVRT)测控系统,监控测试风机的抗干扰性,提出一种在非实时系统中的高精度毫秒级定时方案,使用OS自带的定时函数嵌套调用实现精确定时的方法,解决了LVRT实时控制系统中高精度定时和资源占用率之间的矛盾,满足35kV/6MVA固定式电压跌落发生装置模拟电网的电压跌落与恢复精度,实现对电压跌落实时控制,同时实现了对电压跌落与恢复时风电机组运行状态的实时监测。该测控系统性能达到国际先进水平,已在风机电组低电压穿越测试中投入使用。 相似文献
9.
This paper considers the formal design for the grid frequency control in an offshore wind farm connected with line-commutated converter high voltage dc (HVDC) link. The control paradigm is based on using the grid frequency control to regulate the HVDC rectifier firing angle or dc-link current and hence control the power flow in the system. The dynamic behaviors of the system are verified by comparing the response from derived transfer functions and PSCAD simulations; hence the grid frequency controllers are designed. The control system performance has been validated by simulations of normal operation and fault regimes. The work provides a good basis for wider research investigation into wind farm operation. 相似文献
10.
Power Injection System for Grid-Connected Photovoltaic Generation Systems Based on Two Collaborative Voltage Source Inverters 总被引:1,自引:0,他引:1
Romero-Cadaval E. Milanes-Montero M.I. Gonzalez-Romera E. Barrero-Gonzalez F. 《Industrial Electronics, IEEE Transactions on》2009,56(11):4389-4398
This paper presents a new topology for the power injection system that is based on the parallel association of two voltage source inverters. One operates using a quasi-square voltage waveform strategy, and the other operates with a pulsewidth-modulation (PWM)-based strategy. The aims of this topology are to inject the power from the photovoltaic generation system using the quasi-square inverter and to control the current quality using the PWM inverter. The proposal optimizes the system design, permitting the reduction of system losses and an increase of the energy injected into the grid. 相似文献
11.
Friederich Kupzog Roman Schwalbe Wolfgang Prüggler Benoît Bletterie Serdar Kadam Andreas Abart Markus Radauer 《e & i Elektrotechnik und Informationstechnik》2014,131(6):188-192
European low voltage grids host an increasing amount of energy from rooftop PV installations. Experience in Germany has shown that PV installations do not grow uniformly but with regional hot spots. Meanwhile it is widely agreed that low voltage grids should only be updated to accommodate some 90 % or less of available PV power in peak times in order to avoid extensive costs for grid reinforcement. The main limiting factor in rural distribution grids is the grid voltage. In the Austrian research project “DG DemoNet—Smart LV Grid” new approaches to deal with restricted grid capacities are analysed using active voltage control. In three pilot regions, the actual amount of installed PV is increased to reach physical limits. Voltage control schemes are developed, tested in simulations and then validated in the field. In one pilot region, electric mobility as additional future load in low voltage grids and its integration into the overall system is considered. This paper analyses the performance of the developed control approaches in simulation. 相似文献
12.
Martins G.M. Pomilio J.A. Buso S. Spiazzi G. 《Industrial Electronics, IEEE Transactions on》2006,53(5):1522-1528
The connection of distributed power sources with the utility grid generally needs an electronic power converter for processing the locally generated power and injecting current into the system. If the source provides a dc voltage, the converter must be able to produce a low-distortion high-power-factor ac current. The same aspects related with the voltage and current distortion produced by nonlinear loads can be considered for the injection of power into the grid. In the absence of a specific standard, this paper takes as a reference the limits for current harmonics given by international standards. The justification for this approach is that, from the resulting line voltage degradation, there is no difference between injected and absorbed currents. This paper presents a three-phase inverter using low-frequency commutation. An auxiliary circuit is added to the inverter topology to reduce the output voltage distortion, thus improving the current waveform. The main advantages of this approach are the minimization of the switching losses and the elimination of the electromagnetic interference, which avoids high-frequency filters necessary in high-frequency commutation inverters 相似文献
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14.
风力发电机规模和单机容量不断增大,电网对风力发电机之类的可再生能源并网有着极其严格的要求,其中最具挑战性的要求是低电压穿越,即在电网出现跌落时,要求风机在一定时间内不得脱网,直至发电机发出一定的无功功率帮助电网恢复。本文研究在电网出现大幅跌落时,通过控制撬棒投切的不同时刻,来讨论是否其投切时刻影响着系统从电网吸收的无功功功率,最终通过合理的投切时刻来最大程度上减少系统从电网吸收的无功功率,帮助电网更好的恢复。 相似文献
15.
A voltage feedback active filter is vulnerable to unknown grid impedance. To overcome this problem we propose an identification method, which uses the control system of a frequency selective active filter to measure the grid impedance at selected frequencies. The usefulness of the method is experimentally demonstrated with a 19 kVA active rectifier with a voltage feedback active filtering function. The voltage feedback active filtering is performed in a case in which the active filter control is not stable before the impedance is identified with the method proposed. It is shown that the use of the measured grid impedance in the control system greatly enhances the dynamic stability of the system. Also, the grid impedance measurements are provided in two cases. 相似文献
16.
Le Jian Wang Cao Yang Jintao Zhang Hao Li Xingrui 《International Journal of Electronics》2018,105(11):1881-1899
A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented. 相似文献
17.
The wind energy generation,utilization and its grid penetration in electrical grid are increasing world-wide.The wind generated power is always fluctuating due to its time varying nature and causing stability problem.This weak interconnection of wind generating source in the electrical network affects the power quality and reliability.The localized energy storages shall compensate the fluctuating power and support to strengthen the wind generator in the power system,in this paper,it is proposed to control the voltage source inverter(VSI)in current control mode with energy storage,that is,batteries across the dc bus.The generated wind power can be extracted under varying wind speed and stored in the batteries.This energy storage maintains the stiff voltage across the dc bus of the voltage source inverter.The proposed scheme enhances the stability and reliability of the power system and maintains unity power factor,it can also be operated in stand-alone mode in the power system.The power exchange across the wind generation and the load under dynamic situation is feasible while maintaining the power quality norms at the common point of coupling.It strengthens the weak grid in the power system.This control strategy is evaluated on the test system under dynamic condition by using simulation.The results are verified by comparing the performance of controllers. 相似文献
18.
A Fault Tolerant Doubly Fed Induction Generator Wind Turbine Using a Parallel Grid Side Rectifier and Series Grid Side Converter 总被引:3,自引:0,他引:3
With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride-through disturbances such as faults and support the grid during such events. Conventional modifications to the doubly fed induction generation (DFIG) architecture for providing ride-through result in compromised control of the turbine shaft and grid current during fault events. A DFIG architecture in which the grid side converter is connected in series as opposed to parallel with the grid connection has shown improved low voltage ride through but poor power processing capabilities. In this paper, a unified DFIG wind turbine architecture which employs a parallel grid side rectifier and series grid side converter is presented. The combination of these two converters enables unencumbered power processing and robust voltage disturbance ride through. A dynamic model and control structure for this architecture is developed. The operation of the system is illustrated using computer simulations. 相似文献
19.
《Spectrum, IEEE》2006,43(1):44-47
This paper presents a novel superconducting device that provides essential voltage support. A superconducting synchronous condenser is basically an electric generator that is optimized and operated to act like a capacitor or inductor, providing the grid with reactive power, an abstruse but absolutely vital element in any power system relying on alternating current. The condenser quickly provides large quantities of reactive power to support grid voltage - as much as double the rating for up to a minute from a single unit and to supply controllable continuous-duty reactive compensation for optimizing grid-transmission effectiveness. It promises to do the job more effectively, and possibly more economically, than other solution, especially for industrial voltage flicker applications and voltage regulation of transmission lines with large isolated nodes. 相似文献
20.
为提高区域性电网数据质量检测和评价能力,构建区域性电网数据质量健康管理和监控的变量模型,以电网的配电电能质量指标、输出稳定性以及电压波动等为基准变量,采用多角度评价指标分析的方法进行区域性电网数据的可靠性评估和预测,采用关联信息融合的方法信息区域性电网数据质量评价的统计分析,结合回归分析和检验统计方法实现对区域性电网数据质量评价的目标函数构造,实现区域性电网数据质量评价。仿真结果表明,采用该方法进行区域性电网数据质量评价的准确性较高,对电网监测评价体系的构造完整性较强。 相似文献