基于电流变化量的自适应母线保护

摘要

提出了母线差动保护的自适应判据和母线外部故障时TA饱和的判别方法,用于快速反应母线故障和解决母线区外故障保护误动问题.根据母线外部故障时工频电流变化量差动电流主要表现为母线分布电容电流的变化量,母线内部故障时特别是经高阻故障时可能有一部分穿越性负荷电流流经母线,流进母线的工频变化量电流在流出电流支路的阻抗和故障点等效的过渡电阻之间分配的特点,得到自适应母线保护的动作判据.基于饱和的TA在瞬时电流过零时有一线性传变区,瞬时电流变化量制动电流时间先于瞬时电流变化量差动电流这种特点,得到毋线区外故障时TA饱和的判别方法.提高了保护的可靠性和灵敏度,不受系统运行方式和过渡电阻的影响.%An adaptive criterion for bus differential protection and the distinguish method of faults outside buses are proposed in order to quickly identify bus faults and avoid protection malfunction. The characteristics that method based on are discussed in detail. When fault happens outside buses, power frequency current variation differential current is mainly variation of bus capacitive current. When fault happens inside buses, particularly by high resistance, part of load current can possibly flow through fault buses. Power frequency variation current flowing into buses consists of both fault current and . For TA saturation, there is a linear zone when instantaneous current pass through zero and resisting current of instantaneous current variation current occurs earlier than differential current of instantaneous current variation current. This method improves protection reliability and sensitivity and is not influenced by system operation conditions and transition resistance.