一种自适应的零线断线保护原理与实现

摘要

Neutral line breaking protection mainly uses load voltage and neutral point displacement voltage.The protection setting value needs to greater then maximum load voltage during normal operation,which leads to low protection sensitivity in long and imbalanced transmission lines.In order to solve this problem,an adaptive neutral line disconnection protection is presented.By introducing adaptive coefficient,the protection setting value is adjusted adaptively according to load imbalance during normal operation.The proposed method has good breaking effect during normal operation,and improve protection sensitivity during neutral line disconnection.The simulation model established by Matlab verifies feasibility of proposed protection.%基于负载电压或中性点偏移电压的零线断线保护,其定值的整定需考虑躲过零线正常运行时出现的最大负载电压或中性点位移电压,对于比较长且负载不对称度较大的线路,保护的灵敏度比较低.通过引入自适应系数,对中性点偏移电压的保护判据进行了改进,使保护定值能随负载的不对称度进行自适应调整,既在零线正常运行时起到良好的制动作用,同时也提高了零线断线时保护的灵敏度.并通过Matlab软件建立仿真模型,验证了该保护方案的可行性、合理性和有效性.