基于正序电流故障分量的有源配电网线路差动保护

Differential Protection of Active Distribution Network Based on Adaptive Adjustment of Braking Coefficient

传统配电网在大量分布式电源接入后变为有源配电网,拓扑结构与故障特征发生改变,现有电流差动保护无法同时满足可靠性与灵敏性要求。为此分析了逆变型分布式电源故障输出特性,建立有源配电网正序电流故障分量网络,在此基础上提出一种基于正序电流故障分量的电流差动保护方案。该方案以线路两侧正序电流故障分量为特征量对常规电流差动保护进行改造,解决了在分布式电源接入后线路发生区内高过渡电阻故障引起的电流差动保护无法准确识别故障的问题。最后使用PSCAD/EMTDC对该方案在不同工况下的动作情况进行仿真,仿真结果表明该方案能够适应有源配电网保护需求。

When a large number of distributed generators are connected to the traditional distribution network,the topology and fault characteristics change,and the existing current differential protection cannot meet the requirements of reliability and sensitivity at the same time.Therefore,the fault output characteristics of inverter distributed power supply are analyzed,and positive sequence current fault component network of active distribution network is established.On this basis,a current differential protection scheme based on positive sequence current fault component is proposed.This scheme takes the positive sequence current fault component on both sides of the line as the characteristic quantity to transform the conventional current differential protection,which solves the problem that the current differential protection cannot accurately identify the fault caused by the high transition resistance fault in the line after the distributed generator is connected.Finally,PSCAD/EMTDC is used to simulate the scheme in different working conditions.The simulation results show that the scheme can meet the protection requirements of active distribution network.