直驱风电场PCC点联络线故障电流特性及其对纵差保护影响

Analysis of Fault Current Characteristics of Tie-Line at PMSG Wind-farm's PCC and Its Influences on Differential Protection

根据新疆某风电场并入主网的实际参数,利用PSCAD/EMTDC电磁暂态仿真软件,搭建了基于dq分解法和滞环跟踪法2种控制策略的直驱风电机组模型及基于计及尾流效应等值风速法的并网风电场等值模型;仿真分析了故障类型、控制策略、风速条件均变化时风电场出口处短路特性及其对风电场与电网110 k V联络线上光纤电流纵差保护的影响。仿真结果表明,风电场外部发生短路故障时,其提供的短路电流有效值小于同容量火电,但波动性强,对并网点(point of common coupling,PCC)处保护装置有很大的影响。针对可能出现的问题,提出相应的改进措施,为大规模风电并网提供理论基础。

Based on the actual parameters of a wind farm which is integrated with Xinjiang grid. The PMSG model, which is based on d-q decomposition and hysteresis tracking method, and the wind farm equivalent model, which is based on the account wake effect equivalent velocity taw, are built on tbe platform of PSCAD/EMTDC. A simulation is conducted on the characteristics of the short-circuit at the exit of the wind farm and its impacts on the differential protection of transmission line current integrated with the 110 kV grid under variations of wind speed, control strategy and fault type. The simulation results show that when a short circuit fault occurs outside the wind farm, the virtual value of short-circuit current provided by the wind farm is smaller than that of thermal power with same capacity but has strong volatility and has a significant influences on the protective devices at the PCC （Point of Common Coupling） of wind farms. Some improvement measures are proposed in view of the problems that may arise, which can provide a theoretical basis for large-scale integration of wind powers.