利用测后模拟的谐振接地系统故障选线方法

A New Approach to Detect Fault Line in Resonant Earthed System Using Simulation After Test

分析谐振接地系统单相接地故障零序网络特性,提出了着眼于电路响应求解的故障选线测后模拟方法。根据谐振接地系统故障母线零序电压实测值和馈线零序分布电容参数,在依次假设各馈线为健全馈线的前提下,运用测后模拟法定量地求解各馈线的零序电流。比较各馈线零序电流的实测波形和由测后模拟方法所求解的波形发现:健全馈线零序电流的实测波形和由测后模拟法所求解的波形相吻合,具有极强的相似性;而故障馈线零序电流的模拟波形是在假设其正常工作的条件下获取的,实测波形和模拟波形差异较大。对各馈线零序电流的实测波形和由测后模拟法所求解的波形在一定数据窗下进行相关度分析,籍此形成选线判据,实现选线。大量仿真表明,该方法选线准确、可靠。

A new approach for fault line detection using simulation after test （SAT） with the view to resolve circuit response to the fault is proposed by analyzing the characteristic of zero sequence network of resonant earthed system with single-phase-to-ground fault. Supposing each feeder line is un-faulted, zero sequence current of each feeder line is obtained by using the algorithm of SAT, based on measured zero sequence voltage of bus and zero sequence distributed capacitance of each feeder. The conclusion is gained that measured waveforrn and simulated waveform of un-faulted feeder lines are anastomotic and have great comparability, but those of faulted feeder line has much difference compared with its simulated waveform. The criterion is formed and the fault line is detected according to the analysis of correlation degree of measured waveform and simulated waveform of each feeder line＇s zero sequence current. Large amount of simulation results verify the veracity and reliability of the proposed method when to distinguish all kinds of single-phase-to- ground faults.