一种城市配电网自适应全线电流保护方法

An adaptive full-line current protection method for an urban distribution network

针对现有电流速断保护无法保护线路全长且可能失去保护范围的问题,提出一种双层判据的自适应全线电流保护方法。该保护方法先通过第一层判据中可自适应调整的低整定值,实现不受系统运行方式与故障类型影响的全线故障监测,再利用第二层判据实现线路故障区段定位,确保保护正确动作。考虑到电流保护难以准确辨识高阻接地故障,通过分析系统零序网络,提出一种基于复合功率的高阻接地故障辨识方法。仿真结果表明,所提保护方法不受系统负荷变化及故障类型影响,可有效提升配电网线路保护范围及高阻接地故障辨识能力,保障保护动作的可靠性及灵敏性。

Existing current break protection cannot protect the full length of the line and may lose the protection range.Thus an adaptive full-line current protection method with double-layer criterion is proposed.The protection method first realizes the full-line fault monitoring that is not affected by the system operation mode and fault type through the low adaptive adjustment value in the first layer of the criterion.Then it uses the second layer of the criterion to locate the line fault section to ensure the correct protection action.Considering that it is difficult to accurately identify high-impedance ground faults for current protection,a method based on composite power is proposed by analyzing the zero-sequence network of the system.Simulation results show that the proposed protection method is not affected by system load changes and fault types.This can effectively improve the protection range of distribution network lines and the identification ability of high-impedance ground faults,and ensure the reliability and sensitivity of protection actions.