光伏并网逆变器控制策略研究及仿真实验

Study on Control Strategy and Simulation Experiment of Photovoltaic Grid-connected Inverter

光伏并网发电系统通过逆变器并网时会产生高次谐波并且会消耗无功电能,由于电力系统中大量感性负载的使用,会导致电网特别是电网末端的电网质量下降。因此,在光伏并网逆变器控制中实现有功并网的同时需要具有补偿无功与谐波电流的功能。首先介绍了并网逆变器的拓扑结构以及控制原理;其次介绍了无功与谐波电流检测的方法;针对逆变器并网电流控制环节,比例谐振(PR)控制器在电网频率产生偏移时谐波抑制效果变差,提出了PI-PR控制实现并网电流的零稳态误差控制,并且大大降低了电网频率偏移的影响。理论分析与仿真结果吻合,验证了所提方法的有效性。

The grid-connected photovohaic power generation system will produce mglaer narmomcs anu consume reactive power in grid connection through the inverter. The use of lots of inductive loads in power system will cause the reduction of power quality in power grid especially in the terminal of power grid. Therefore ,to achieve active grid connection in the control of photovoltaic grid-connected inverter requires the fuhction of compensation of reactive power and harmonic current at the same time. The paper first introduces the topological structure and control principle of grid-connected inverter;and then it introduces detection methods of reactive power and harmonic current;in light of inverter grid current control link where the harmonic suppression of proportional resonant （PR） controller is less effective when grid frequency causes an offset,this paper presents that PI-PR control achieves zero steady-state error control of grid current,and greatly reduces the impact of the grid： frequency deviation. Theoretical analysis and simulation results coincide, verifying the effectiveness of the proposed method.