基于dq锁相环的改进型光伏电站并网点电压跌落检测方法研究

摘要

Fast and accurately detecting different types of grid-connected point voltage sag faults is the precondition to achieve low voltage ride through of photovoltaic power station. For the conventional voltage sag detection methods based on dq-PLL can not detect voltage unsymmetrical sag faults because of the negative sequence components of voltage. A sequence separation method based on second-order generalized integral is adopted to separate the sequences of voltage, filtering the negative sequence components and entering the positive sequence components into enter the PLL. In this way, the detection of voltage unsymmetrical sag faults can be realized. The simulation results based on MATLAB/Simulink verified the above method has higher detection accuracy for several types of voltage sag faults, and the feasibility of the method is proved.%快速准确检测出并网点电压不同类型的跌落故障是光伏电站实现低电压穿越的前提。针对电压负序分量导致基于dq锁相环的常规检测方法无法检测电压不对称跌落的问题，采用二阶广义积分法对电压进行相序分离，滤除负序分量让正序分量进入锁相环，实现对电压不对称跌落故障的检测。基于Matlab/Simulink搭建了仿真平台，仿真结果表明上述方法对多种类型的电压跌落故障有较高检测精度，验证了该方法的可行性。