中文摘要：

分析了同杆双回线内部发生接地故障时故障线路及相邻线路上零序反时限过流保护的动作特性。分析结果表明当故障位置与两侧系统参数满足特定条件时,双回线相邻线路上的零序反时限保护可能误动,故障线路两端保护的灵敏度配合可能存在问题。提出一种改变相邻线路保护时间整定系数的方法来避免可能出现的保护误动,该方法通过增加相邻线路保护动作延时来保证双回线保护优先动作,但也给相邻线路保护的速动性带来不利影响。此外故障线路两端保护的动作时间可能相差较大,不利于故障的快速切除。为此设计了基于零序电流变化和零序功率方向的加速方案,无论双回线故障还是双回线相邻线路故障,均能确保故障线路保护优先动作,从而保证各处保护的选择性和速动性。算例仿真验证了分析结论的正确性和所提加速方案的可行性。

英文摘要：

The operating characteristics of zero-sequence inverse-time overcurrent protections of the faulty and adjacent lines during the internal grounding fault of double-circuit lines on same tower are analyzed and results show that,when the fault location and the system parameters of both sides meet some conditions,the zero-sequence inverse-time overcurrent protections of the adjacent lines may malfunction and the protection sensitivities of two ends of the faulty line may mismatch. It is proposed to change the protection TDS（Time Dial Setting） of adjacent line to avoid the possible malfunction,which ensures the protections of doublecircuit lines function first by increasing the time-delay of the protections of adjacent lines,but also reduces their sensitivity. Besides,the protections at both sides of faulty line may have quite different operating times,unfavourable for the rapid fault removal. Therefore,acceleration schemes respectively based on zero-sequence power direction and zero-sequence current variation are put forward,which ensures the protections of faulty line function first,either double-circuit lines or adjacent lines. The selectivity and sensitivity of all the protections are ensured. Simulative results prove the validity of the analytical results and the feasibility of the proposed acceleration scheme.