保护在同杆双回线动模试验中的动作分析

Performance analysis of line protection in dynamic simulation of double lines on same tower

对一种超高压数字式线路保护装置在同杆并架双回线路500kV动模系统上的试验情况进行了分析。与单回线保护相比,同杆并架双回线保护必须解决在跨线、转换性等复杂故障下的选相跳闸问题。在500kV系统200km及400km线路长度的同杆并架双回线模型上,以及41km的三角环模型上所做的动模试验,表明所采用的突变量选相元件及负序零序电流选相元件不能完全正确地选相,阻抗元件一般情况下可以满足双回线故障的要求,但应注意跨线不接地故障及零序互感对阻抗元件的影响,长线路重负荷下转换性故障可能使纵联零序电流保护灵敏度不足。试验是在RTDS设备上进行的,试验表明解决这些问题所采取的措施可行。

The performance of a single-line digital EHV line protection in the dynamic simulation system of500kV double lines on same tower is analyzed.Compared with its application to single line system,when the protection is used in double line system,the phase selection and trip is the necessary function for inter-line fault and conversion fault.The dynamic simulation with500kV,200km and400km double-lines-on-same-tower system models and41km triangle system model are carried out .It shows that the fault-phase-selection element of sudden-change phase-current or of zero-and negative-sequence currents can not properly select the fault phase all time.The impedance element meets the requirements in general,but it is affected by ungrounded inter-line fault and by zero-sequence mutual inductance.The sensitivity of pilot zero-sequence current may be insufficient under conversion fault with long line and heavy load.The test on RTDS(Real Time Dynamic Simu-lator)device indicates that the problems can be solved by the proposed measures.