风电并网LCL滤波逆变器电容电压反馈控制

Capacitor Voltage Feedback Control for Grid-connected Wind Power Generation Inverter With LCL Filter

针对传统LCL滤波器在电容上串联电阻造成的能量损耗,提出采用滤波器电容电压估计值的高频分量作为反馈变量的控制策略,以此提高系统的阻尼,抑制LCL固有谐振。对于风力发电用逆变器多应用于频率不稳的弱电网的情况,引入含有阻尼因子的比例谐振(PR)控制,在系统频率波动范围较大时,也能有效抑制系统频率处的谐振。提出的控制策略在保证系统阻尼的同时,减少了系统损耗,特别适用于大功率低电压应用场合。实验验证了控制策略的正确性和有效性。

For the energy loss caused by the resistor in series with capacitor, a control strategy based on filter＇s capacitor voltage feedback is proposed in order to improve system damping and inhibit the inherent resonance of LCL filter.For the application of inverter in wind power generation,frequency fluctuation is the most commonly in weak grid.A proportional resonant（PR） regulator with damping coefficient is introduced,in the situation of wide range frequency fluctuation, it can suppress the resonance peak effectively at point of system frequency.The proposed strategy provides enough damping for system,and reduces loss dramatically.It is suitable for application with low voltage and high power especially.Feasibility and correctness of the proposed control strategy are validated by experiment.