基于电压平衡控制的光伏并网系统研究

摘要

设计了一种具有直流侧电压平衡功能的光伏并网系统，系统采用级联型多电平逆变器，当功率单元直流侧电压不平衡时，通过对占空比进行微调实现电压平衡控制，从而改善输出波形，提高电能质量；且控制器引入电网电压前馈，以消除电网电压畸变或扰动对逆变器输出造成的影响，更好地满足了光伏发电并网的特殊要求。理论分析和仿真结果验证了该系统的正确性和实用性。%　　A kind of grid-connected photovoltaic system with voltage-balanced function at DC side was designed. The system ad-opted cascaded multilevel inverter, and when the voltage of power unit at DC side was not balanced, the system adjusted the duty in some sort to realize voltage-balanced control, thus to improve output waves and to raise electric energy quality. The controller introduced grid voltage feed-forward and eliminated impacts of grid voltage distortion or disturbance on inverter output. The design meets the special requirements of grid-connected photovoltaic system. The theoretical analysis and simulation results have verified correctness and practical property of the system.