反应重负荷下高阻故障的稳态量线路差动保护判据

Current Differential Protection Criterion Using Steady Currents for Heavy-load Line With High Fault Resistance

指出传统稳态量差动保护判据受穿越电流影响,导致重负荷接地故障情况下带过渡电阻能力弱,提出一种改进的稳态量电流差动判据,对两种判据灵敏度的理论分析表明,改进判据在内部带电阻接地故障中,具有较高的灵敏度,特别是对重负荷下的高阻接地故障,表现出明显的优越性。根据一条750 kV线路故障和保护的仿真试验,证明该电流差动改进判据较传统稳态量判据,在保证区外故障安全性的基础上,对重负荷状况下的带过渡电阻能力有很大的提高,是一种比较理想的超高压或特高压输电线路电流差动保护判据。

It is analyzed that the criterion of current differential protection using steady currents is not able to operate at internal faults under the condition of high fault resistance and heavy-loads due to through currents. An improved steady current differential protection criterion is proposed. The sensitivities of these two criteria are analytically compared. The improved criterion possesses higher sensitivity at an internal ground fault with fault resistance and is especially superior on the conventional one under the condition of high fault resistance and heavy-loads. Simulation of faults and the two protection criteria on a 750 kV line proves that the proposed criterion has achieved a great improvement on the abilities of detecting high resistance internal faults in the heavy-load condition with guarantee of security at external faults. It is a proper current differential protection criterion for EHV／UHV transmission lines.