并联逆变器电压前馈谐振抑制方法研究

Research on voltage feedforward resonance suppression method for parallel inverters

在弱电网条件下,并联逆变器与电网阻抗相互耦合容易引发谐波谐振,严重影响并网电能质量。首先,建立了多逆变器并联系统的等效电路模型,从阻抗角度分析了谐波谐振产生机理;其次,通过在逆变器(point of common coupling,PCC)电压前馈通道引入二阶低通滤波器,改善谐振频率处的逆变器输出阻抗特性,并利用阻抗稳定判据验证其有效性;最后,在Simulink中进行仿真实验,结果表明该方法可以有效抑制多逆变器并联系统的谐振危害,同时可以提高逆变器对弱电网的适应能力。

Under weak grid conditions,coupling parallel inverters and grid impedance can easily cause harmonic resonance,seriously affecting the quality of grid-connected power.First,an equivalent circuit model for a multi-inverter parallel system is established,and the mechanism of harmonic resonance generation is analyzed from the perspective of impedance.Secondlly,by introducing a second-order low-pass filter into the PCC voltage feedforward channel of the inverter,the output impedance characteristics at the resonant frequency are enhanced,and its effectiveness is verified using impedance stability criteria.Finally,simulation experiments conducted in Simulink show that this method can effectively suppress the resonance hazards in multi-inverter parallel systems and improve the adaptability of inverters to weak grids.