基于负序电压前馈的非对称故障下低电压穿越控制方法研究

RESEARCH OF LOW VOLTAGE RIDE THROUGH CONTROL STRATEGY BASED ON NEGATIVE SEQUENCE VOLTAGE FEEDFORWARD UNDER UNSYMMETRICAL FAULT

以电网发生非对称故障期间的双级式光伏并网发电系统为研究对象,首先利用LES（least error squares）滤波器提取电网电压基波分量,并采用二阶广义积分器锁相环分离电压负序分量。提出基于负序电压前馈的非对称故障下低电压穿越控制方法,以抑制电网电压负序分量造成的并网功率二倍频畸变,提高光伏发电系统的低电压穿越性能。仿真及实验结果均证明所提方法的正确性和有效性。

Taking the two-stage PV grid connected power generation system under asymmetrical faults of power grid as the research object, firstly, the LES filter is used to extract the fundamental voltage component of the power grid, and the second order generalized-integrator phase locked loop is used to separate the voltage negative sequence components. The low-voltage ride-through control method based on negative sequence voltage feedforward for asymmetric faults is proposed, which can suppress two-fold distortion of grid-connected power caused by negative-sequence components of grid voltage to improve low-voltage ride-through performance of PV power generation system. Both simulation and experiment results prove correctness and validity of the proposed control strategy.