考虑风力发电的配电网弱馈线路自适应电流保护

An Adaptive Current Protection for Weak-Infeed Distribution Lines with Wind Generation

风力发电接入配电网后,配电线路的潮流及故障电流特征发生了改变,风力发电机故障后由于撬棒电路的投入导致风机的正、负序阻抗不再相等,使得以电源正、负序阻抗相等为前提的电流保护整定方案失去合理依据。通过对含风力发电的配电网弱馈线路不同位置发生两相相间短路和三相短路的故障特性进行研究,结合自适应保护的实时在线整定功能,引入含风力发电的电流Ⅰ段和Ⅱ段保护整定修正系数,改善了传统配电网电流保护的性能。最后,通过对含有风力发电的配电网弱馈线路进行仿真,验证了所提保护方案的有效性。

With the connection of wind generators to the distribution network,the load flow and the characteristics of the fault currents of the distribution lines have been changed. Due to the introduction of the chopper circuits after faults,wind generators＇ positive and negative sequence impedances are not equal any more,which leads to the loss of the foundation of the relays＇ setting principles. In this paper,the characteristics of the phase-to-phase fault and three-phase fault at different locations of the weak-infeed distribution lines connected with wind generators are analyzed. Hence,while calculating the setting values of the instantaneous overcurrent protections and time delay instantaneous overcurrent protections of those lines,correction factors are utilized to overcome the influences of the wind generators with the help of the real-time online setting of the adaptive protection. Finally,a simulation is carried out to validate the effectiveness of the proposed scheme.