级联陷波滤波器的微型光伏逆变器谐波抑制

Cascaded Notch Filters for Harmonic Suppression of Micro-photovoltaic Inverters

直流母线上出现的二倍频纹波电压会导致单相并网逆变器的基准电流失真,并使其向电网注入过多的3次谐波电流,进而严重影响电网的电能质量。为此,这里提出一种基于级联陷波滤波器的双级半桥微型光伏逆变器谐波抑制控制策略,引入级联陷波滤波器来削弱电压控制环中的谐波分量,从而产生平滑的参考功率并提高注入电网的电流质量。首先分析功率去耦电容对直流母线纹波电压的影响,接着对双级半桥微型逆变器的谐波电流进行建模,并在传统的电压环PI控制器的基础上,引入级联陷波滤波器来减轻二阶谐波电流和三阶谐波电流。最后搭建实验样机对所提方案进行验证,实验结果表明即使两个直流电容容值差为±20%的情况下,所提设计方案仍然能满足IEEE-1547标准的要求,同时拥有良好的稳态和动态响应性能。

The double-wire frequency ripple voltage on the DC bus will cause the reference current distortion of the single-phase grid-connected inverter,and make it inject too much third harmonic current into the grid,which will seriously affect the power quality of the grid.Therefore,a two-stage half-bridge micro-photovoltaic inverter harmonic suppression control strategy based on cascade notch filter is proposed.The cascade notch filter is introduced to weaken the harmonic components in the voltage control loop,so as to generate smooth reference power and improve the quality of current injected into the grid.Firstly,the influence of power decoupling capacitor on DC bus ripple voltage is analyzed,and then the harmonic current of two-stage half-bridge micro-inverter is modeled.Based on the traditional voltage loop PI controller,cascade notch filter is introduced to reduce the second and third harmonic current.Finally,an experimental prototype is built to verify the proposed scheme.The experimental results show that the proposed design scheme can still meet the requirements of IEEE-1547 standard and has good steady-state and dynamic response performance even if the difference between the two DC capacitance values is ±20%.