光伏并网逆变器负序分量补偿法控制策略

Negative Component Compensation Control Scheme for Photovoltaic Grid-connected Inverter

为了抑制电网不平衡时三相光伏并网逆变器侧并网电流所产生的畸变,提出了一种基于d-q坐标系下的负序分量补偿法,用于抑制逆变器侧并网电流的不平衡。分析了电网不平衡情况下的数学模型,证明了A相电压故障前后d-q坐标系下正负序电压分量的关系。采用基于二阶广义积分的带通滤波器获取α-β坐标系下的正负序电压,进行负序电压补偿,形成新d-q坐标系下的电压分量。此控制方法可以抑制电流谐波,消除并网电流畸变,使电网不平衡期间并网电流不超过其额定值,避免因电流过大而使光伏系统从电网断开的故障发生。通过仿真和实验验证了该控制算法的正确性和有效性。

According to the grid current distortion on the photovoltaic（PV） grid-connected inverter side during grid unbalance,we proposed a negative sequence component compensation unbalanced control strategy based on d-q reference frame to suppress the current on grid-connected inverter side.After analyzing the mathematical model of unbalanced grid,the relationship of positive and negative sequences voltage components in d-q reference frame before and after an phase fault was demonstrated,and then a band-pass filter based on second-order generalized integrator（SOGI） was used to obtain the positive-negative sequence component to compensate the voltage and to form a new d-q reference voltage.The proposed method can suppress current harmonics,eliminate grid current distortion,and make the grid current within its rated value to avoid the PV system disconnecting from power grid.Further simulation and experiments results confirm the validity and efficacy of the proposed strategy.