DG容量对配电网电流保护的影响及对策研究

Research on the impact of DG capacity on the distribution network current protection and countermeasure

含DG的配电网线路在发生短路故障时,分布式电源的注入电流可能会影响流过该线路保护装置的短路电流,导致保护误动或拒动,因此需要根据电流保护分析DG的准入容量问题。分析了分布式电源并入配电网后,在线路不同位置发生短路故障时,DG对短路电流产生的助增、汲流和反方向电流影响,并推导出含DG的配电网短路电流计算公式。在此基础上,求出DG为不同容量时,流过保护的短路电流变化曲线。并根据配电网电流保护整定值,求出保证保护正确动作的DG最大准入容量。

When short circuit fault occurs in the transmission line of distribution network with DG connected, the injection current of the distributed generation may have an impact on the short circuit current, which flows through the current protection of the transmission line, and causes the protection misoperation or failure action, so the penetration level of DG needs to be analyzed according to the current protection. This paper analyzes the impact of DG on the protection, when the short circuit fault occurs at different positions of the transmission line, including increasing flow, decreasing flow and the opposite direction flow. At the same time, the short circuit current calculation formula of the distribution network with DG connected is deduced. On this basis, it calculates the short circuit current flowing through the current protection. According to the protection setting values, the maximum penetration level of DG connected into distribution network is analyzed, in order to ensure the current protection correct operation. This work is supported by the Educational Ministry Program for New Century Excellent Talents.