共查询到19条相似文献,搜索用时 171 毫秒
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文章对带工频隔离变压器的单相光伏并网逆变器产生偏磁进行了分析,为解决输出的直流偏磁对逆变器的不良影响,提出一种通过对调制波进行直接处理的全数字化基于脉宽处理的偏磁抑制方法,为验证其有效性,在3 kW单相光伏并网逆变器的样机上进行了试验验证,采用单极性倍频的SPWM调制方式。试验结果表明,该偏磁抑制方法能有效地抑制变压器的直流偏磁。 相似文献
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针对光伏发电系统通常以单位功率因数运行,造成故障时光伏并网逆变器一定视在功率浪费的现状,提出一种低电压穿越无功控制策略。分析光伏并网逆变器的有功、无功功率解耦控制和其无功功率输出极限,建立光伏逆变器无功功率输出与并网点电压跌落的关系,通过比较故障前光伏阵列发出有功功率与光伏逆变器允许输出最大有功功率,确定光伏发电系统在低电压穿越过程以最大功率模式运行或者以非最大功率模式运行。利用RTDS软件搭建仿真算例,验证该低电压穿越无功控制策略的可行性。 相似文献
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为实现“双碳”及“铜退硅进”的目标,非隔离型逆变器在光伏新能源发电领域得到了广泛的研究与应用。非隔离光伏并网系统中存在的漏电流问题是迫切需要解决的关键问题之一。为解决该问题,文中提出了一种新型单级共地型无漏电流,高效率非隔离光伏并网逆变器拓扑结构。分析了所提逆变器前级DC-DC升降压电路的工作原理和模态,给出了其软开关实现条件。研究了新型拓扑结构的无漏电流内在机理,以及推导了其输出电压特性。搭建了基于PSIM软件的仿真模型,仿真结果表明:与传统漏电流抑制拓扑相比,该拓扑结构可实现无漏电流光伏并网,而且前级DC-DC变换器可实现软开关,可在较宽输入电压范围内实现高效率、高质量电能并网。 相似文献
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随着分布式发电技术的快速发展,并网光伏系统应用日益广泛。并网光伏系统短路特性不同于传统同步发电机电网系统,因此,从逆变器拓扑结构出发,依据P/Q控制策略,利用MATLAB/simulink建立仿真模型,得到并网光伏系统在不同故障情况下的电流输出曲线,分析并网光伏系统的短路特性,对于并网光伏系统的研究工作具有实际意义。 相似文献
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鉴于光伏发电并网逆变器的建模对于光伏大规模接入、保障系统稳定运行具有重要意义,提出了系统仿真方案,利用Hammerstein-Wiener(HW)非线性模型对光伏并网逆变器的运行进行仿真。通过试验获得直流逆变器电压电流波形、交流逆变器电压电流波形、电压公共耦合点、电网和负荷电流;利用编程确定各种模拟波形并搜索与实际波形相比最准确的模型,同时将该方法运用到电能质量分析中,进而完成对系统的分析和建模。模拟结果表明,该模型效果较好,可以为系统规划、防止系统故障和改善电能质量等方面提供理论依据。 相似文献
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A fast and robust control strategy for a multilevel inverter in grid-connected photovoltaic system is presented. The multilevel inverter is based on a dual two-level inverter topology. There are two isolated PV generators that feeding each bridge inverter. The output of each inverter is connected to a three-phase transformer. The active and reactive powers flowing into the grid are controlled by a sliding mode algorithm. An alfa–beta space vector modulator is also used. The inverters DC voltages are also controller by a sliding mode controller. In this way, a fast and robust system controller is obtained. Several test results are presented in order to verify the effectiveness of the proposed system controller. 相似文献
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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. 相似文献
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A multi-function grid connected PV system with three level NPC inverter and voltage oriented control
In this paper a grid connected photovoltaic (PV) system is presented. The grid integration of the PV system is carried out via a three phase three level neutral point clamped (NPC) inverter. To control the inverter a modified version of voltage oriented control (VOC) method and the space vector pulse width modulation (SVPWM) technique have been applied. With the proposed modification the PV system operates as a shunt active power filter (SAPF), a reactive power compensator, and a load’s current balancer simultaneously. In this way the PV system operates more efficiently compared to the conventional PV systems and offers ancillary services to electric power system. The effectiveness of the proposed control scheme is established through simulation results with Matlab/Simulink in steady state and transient response of the electric power distribution system. 相似文献
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This study presents a reactive power controller using Probabilistic Wavelet Fuzzy Neural Network (PWFNN) for grid-connected three-phase PhotoVoltaic (PV) system during grid faults. The controller also considers the ratio of the injected reactive current to meet the Low Voltage Ride Through (LVRT) regulation. Moreover, the balance of the active power between the PV panel and the grid-connected inverter during grid faults is controlled by the dc-link bus voltage. Furthermore, to reduce the risk of over-current during LVRT operation, a current limit is predefined for the injection of reactive current. The main contribution of this study is the introduction of the PWFNN controller for reactive and active power control that provides LVRT operation with power balance under various grid fault conditions. Finally, some experimental tests are realized to validate the effectiveness of the proposed controller. 相似文献
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This work deals with the performances and responses of a grid-connected photovoltaic (PV) plant in normal and disturbed modes. The system is composed of a solar array, a dc–dc converter and a three-phase inverter connected to the utility grid. On the one hand a suitable control of the dc–dc converter is developed in order to extract the maximum amount of power from the PV generator. On the other hand an active and reactive power control approach (PQ) has been presented for the inverter. This method can provide a current with sinusoidal waveform and ensure a high power factor. Therefore, the grid interface inverter transfers the energy drawn from the PV into the grid by ensuring constant dc link voltage. Modeling and controlling were carried out using the informational graph of causality and the macroscopic energy representation methods. The simulation under MATLAB/SIMULINK and the experimental results show the control performance and dynamic behavior of grid-connected PV system in normal and disturbances modes. 相似文献
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《Energy Conversion, IEEE Transaction on》2009,24(1):93-101
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为实现电网电压不平衡时对T型三电平光伏并网系统输出功率和电流质量的控制,以达到入网功率平稳或电流正弦为控制目标,结合光伏阵列输出功率前馈,在两相静止坐标系下提出一种直流母线电压外环PI控制、并网电流内环有限集模型预测控制的控制策略,并在电压外环中引入2倍频陷波器以获得平滑的入网功率参考值。仿真结果表明:当电网电压不对称时,采用所提控制策略能够实现对入网有功、无功功率2倍频脉动及负序电流的分别抑制或协调控制,且并网电流谐波畸变小、入网电能质量高,同时实现T型三电平逆变器的中点电位平衡。 相似文献