含低电压穿越型光伏电源配电网自适应正序电流速断保护

摘要

在配电网发生故障的情况下,具有低电压穿越(Low Voltage Ride Through,LVRT)能力的光伏电源(PV)的输出电流与PV容量、故障类型以及故障位置等因素密切相关,这给配电网电流保护的整定带来了很大困难.分析了PV的低电压穿越运行特性及控制策略,给出了含PV配电网的故障分析方法.并结合含PV配电网故障时短路电流的特点,分析了现有配电网自适应电流速断保护存在的问题,针对PV只输出正序电流这一特点,提出了一种适用于多个PV接入的配电网自适应正序电流速断保护.利用PSCAD建立了一个10 kV配电系统模型,仿真验证了该保护的正确性.%In the case of distribution network failure,the output current ofphotovoltaic power plants which have capability of low voltage ride-through (LVRT) is closely related to the PV capacity,fault type and fault location.It brings great difficulties to the current protection of distribution network.The characteristics and control strategies of low voltage ride-through of PV are analyzed.A fault analysis method of distribution network with PV is proposed.Based on the failure characteristics of distribution network with PV,the problem of adaptive current instantaneous trip protection in distribution network is analyzed.Because PV only output positive sequence current,an adaptive positive-sequence current instantaneous trip protection for distribution network with PV is put forward.A 10 kV model of distribution network is established by using PSCAD,verifying the correctness of the protection.