不对称故障条件下并网光伏逆变器功率波动与电流抑制改进控制策略

An Improved Control Strategy of Power Fluctuation and Current Suppression for Grid-connected Photovoltaic Inverter Under Unbalanced Fault Condition

电网出现不对称故障时三相光伏并网逆变器会产生较大的有功和无功功率波动、谐波电流以及峰值电流,本文针对不对称故障条件下光伏逆变器的功率控制进行研究,提出一种能够抑制功率波动、输出电流谐波以及峰值电流的改进控制策略,在已有参考电流算法基础上加入多个调节参数,分析了功率波动、输出电流谐波以及峰值电流同参数之间的关系,提出了调节参数的确定原则及限功率措施,通过在PSCAD/EMTDC中建立仿真模型验证了所提出控制策略的正确性。

Three-phase grid-connected photovoltaic inverter will cause active and reactive power fluctuations,produce apparent harmonic currents,and increase peak current under unbalance voltage faults condition.In this paper,the power control of photovoltaic inverter under unbalanced fault condition is studied,and an advanced control strategy which can restrain the fluctuation of active power,reactive power,output harmonic currents and peak current is proposed.By adding several adjusting parameters based on the existing reference current algorithm,the relationships between harmonic current,power fluctuations,peak current and parameters are analyzed,and the determination principle of adjusting parameters and the power-limited measures are proposed.The simulation models in PSCAD/EMTDC have been built to validate the accuracy of proposed control strategy.