基于谐波注入法的L型光伏并网逆变器谐波抑制方案

Harmonic suppression scheme of L-type photovoltaic grid-connected inverter based on harmonic injection method

在光伏发电并网过程中,由于逆变器的开关特性,输出电流一般都含有低次谐波,其中以5次、7次等低次谐波最为严重。为了抑制并网电流中的低次谐波,降低线路、负载中的电能损耗,本文以L型逆变器为研究对象,提出一种基于SPWM谐波注入的谐波调制方案,在SPWM正弦信号中注入5次、7次谐波补偿电压,进而达到降低输出电流特定次谐波含量及提高并网电能质量的目的。通过MATLAB/Simulink仿真和试验验证了该方案能够有效降低并网电流中特定次谐波含量和谐波畸变率,提高光伏发电并网电能质量。

In the process of photovoltaic power generation, the power quality is not good. The reason is that the output current generally contains low-order harmonics, among which the low-order harmonics of 5 times and 7 times are most serious, due to the switching characteristics of the inverter. In order to suppress the low-order harmonics in the output current and reduce the loss of loads and line, a harmonic suppression control strategy based on grid-connected inverter topology of L-type is proposed in this paper. A harmonic modulation scheme based on SPWM harmonic injection, which is to inject compensation voltage of low-order harmonics of 5th times and 7th times, is discussed in detail. The purpose is reducing the specific harmonics of the output current and improving the power quality of the grid connection. The MATLAB/Simulink simulation and experiment verifies that this scheme can effectively reduce the specific sub-harmonic content in grid-connected current, reduce the harmonic distortion rate and improve the grid-connected power quality of photovoltaic power generation.