LCL型并网逆变器并联谐振机理分析及抑制方法

Parallel Resonance Mechanism Analysis and Suppression Method for LCL Type Grid-Connected Inverter

针对两个并网逆变器并联系统,利用叠加定理分析了各逆变器对并网电流的影响,对并网电流进行分解,研究了由交互电流和公共电流产生谐振的机理,对比分析了相同和不同容量多个并网逆变器并联系统的谐振频率点特性.基于并联系统中交互电流产生的谐振频率点,设计了数字陷波器,引入到传统电容电流反馈有源阻尼控制中,实现了对基波信号的无静差控制,满足了此类系统的并网要求.搭建了相同和不同容量的逆变器并联系统模型,仿真结果验证了所提策略的正确性和有效性.

For the parallel system of two grid-connected inverters,the effect of each inverter on the grid-connected current is analyzed by using the superposition theorem,and the grid-connected current is decomposed.Besides,the mechanism of resonance generated by the interaction current and the common current is studied,and the resonance frequency point characteristics of parallel systems with multiple grid-connected inverters of the same and different capacities are compared and analyzed.Moreover,based on the resonant frequency point generated by the interactive current in the parallel system,a digital notch filter is designed and introduced into the traditional capacitive current feedback active damping control to realize the static-free control of the fundamental signal,which meets grid-connected requirements of such systems.Furthermore,the models of parallel systems of inverters with the same and different capacities are built.The simulation results verify the correctness and effectiveness of the proposed strategy.