适应高比例新能源接入的配电网改进型自适应电流保护方法

Improved adaptive current protection method suitable for distribution network adapted to high proportion of new energy source accessed

在逆变型分布式电源(inverter-interfaced distributed generator,IIDG)高比例接入的新型电力系统中,故障电流呈现非线性变化的特征。传统的自适应保护方案难以适应该特征,且其整定是基于固定的运行方式,并未考虑拓扑结构的变化。为此,提出了一种基于本地信息改进型电流保护方案,易于实施同时兼具经济性。首先,分析了IIDG不同出力状态对故障电流的贡献水平及其对保护性能的影响,并将IIDG的出力聚类为多个状态集;然后,提出了考虑拓扑结构变化的故障电流计算方法,结合分布式电源的出力曲线和配电网的多种运行状态,离线对保护进行整定,通过多点量测信息判断运行状态并切换保护定值;最后,经PSCAD/EMTDC仿真验证了所提方法的有效性,并证明所提方法在考虑IIDG出力波动性的同时能够有效增强对配电网拓扑结构变化的适应能力,为高比例新能源接入后保护方案的优化提供参考。

Under the new type of power system with a high proportion of inverter-interfaced distributed generator(IIDG)access,the fault current shows a nonlinear variation.The traditional adaptive protection scheme is difficult to adapt to this feature,and its adjustment is based on a fixed operation mode without considering the change of topological structure.For this reason,an improved current protection scheme based on local information is proposed,which is easy to implement and economical at the same time.Firstly,the contribution levels of different IIDG power states to the fault current and their influence on the protection performance are analyzed,and the IIDG power is clustered into multiple state sets.Secondly,a fault current calculation method considering topology changes is proposed,and the protection is calibrated offline by combining the power curves of distributed power sources and multiple operating states of the distribution network,judging the operating state and switching the protection value through multi-point measurement information.Finally,the effectiveness of the proposed method is verified by PSCAD/EMTDC simulation,and the proposed method can effectively enhance the adaptability to the topology change of the distribution network while taking into account the fluctuation of IIDG output,which provides a reference for the optimization of the protection scheme after the high proportion of new energy access.