基于故障稳态分量的含DG配电网自适应方向电流保护方案

针对分布式电源(DG)大量接入配电网后保护可靠性低的问题,提出一种基于故障稳态分量的自适应方向电流保护方案。分析不同类型DG的故障暂态特性以及故障等值方法,计算系统短路电流所含分量,并揭示短路电流三相分量之间的关系。在此基础上,根据故障边界条件,获取系统故障稳态分量,再结合保护安装处的测量电压及测量电流,计算保护背侧等值电压和等值阻抗,构造不同故障类型下自适应方向电流保护判据。仿真结果表明该方案不受DG类型、DG出力以及系统运行方式影响,并能有效地防止电压跌落引起的延时保护拒动。

Adaptive directional current protection scheme based on steady state component in distribution network with DG

Aiming at the poor reliability problem of traditional protection in the distribution network with DG(Distributed Generation),an adaptive directional current protection scheme based on steady state com-ponent is proposed. By analyzing the fault transient characteristics and fault equivalent methods of different kinds of DG, components of short circuit current are calculated, and the relationship between three phase components of the short circuit current are revealed. Based on this, the steady state component of system is obtained according to the fault boundary conditions. Then, combined with the measured voltage and current at the relay installation point, the equivalent voltage and the equivalent impedance at backside of relay protection are calculated, with which, an adaptive directional current protection criterion under different fault conditions is established. Simulative results show that immune to DG types, DG output and system operating modes, the proposed scheme can effectively prevent the time relay failure caused by voltage drop.