提出了一种基于故障分量电流幅值与相位差的电流差动保护判据,其中差动电流为本侧电流故障分量幅值加上对侧电流故障分量幅值与二者相位差余弦值之积,制动电流为本侧电流故障分量幅值减去对侧电流故障分量幅值与二者相位差余弦值之积。分析了不同系统阻抗、过渡电阻、分布电容对该差动保护判据性能的影响,并与目前广泛应用的故障分量电流相量差动保护判据和标积制动原理的差动保护判据进行了性能上的对比分析,同时采用EMTDC软件进行了算例仿真。分析计算结果表明,所提的差动保护判据在区内故障时的灵敏度更高,区外故障时的安全性更好,在不同系统阻抗、过渡电阻、分布电容条件下均具有良好的性能。
A criterion of current differential protection is proposed,which is based on the amplitude and phase difference of fault current component. The differential current is the sum of the fault current amplitude on own side and the product of that on opposite side and the cosine of phase difference between them,while the braking current is the difference. The influences of system impedance,transition resistance and distributed capacitance on the performance of the proposed criterion are analyzed. It is compared in performance with the fault current phasor differential criterion and the scalar product braking differential criterion. Results of simulation with EMTDC show that,the proposed criterion has higher sensitivity to inzone faults,higher security for out-zone faults and better performance under different system impedances, transition resistances and distributed capacitances.