配电网线路相间故障重合前无故障识别方法研究

摘要

目前现有配电网线路相间故障采用自动重合闸技术存在重合于未消失故障导致重合不成功的风险,有必要重合前进行无故障识别来避免盲目重合.针对配电网带并联补偿电容器的线路,研究了一种利用并联电容器储能放电的电压电流信息进行相间故障重合前无故障识别方案.分析表明,瞬时故障时,故障熄弧前过渡电阻为较小值,而熄弧后过渡电阻理论上无穷大,且熄弧瞬间过渡电阻存在突变特征;而永久故障时,跳闸后故障过渡电阻持续为较小值.据此特征,提出了利用相间故障过渡电阻的辨识结果进行重合前故障状态的识别方法及判据.最后,PSCAD建模仿真计算分析表明,所提出相间故障重合前无故障识别方法的正确性和有效性,有助于提高配电网相间故障的重合成功率.%There is risk in auto-reclosure currently applied to phase-to-phase faults in distribution network,resulting in the unsuccessful reclosing in the case of the fault,so it is necessary to detect non-fault condition before the reclosing.For the lines with shunt compensation capacitor in the distribution network,a new scheme using the discharging characteristics of the shunt capacitors after tripping is proposed to detect the non-fault condition before the reclosing.The analysis shows that,when a transient fault occurs, there is a minor transition resistance before the arc extinction,an infinite transition resistance after the arc extinction in theory and a sudden change in the resistance in the arc extinction;when a permanent fault occurs,there is a sustained minor transition resistance after the tripping.Based on which the difference among the transition resistances in the phase to phase fault is used to detect the non-fault condition before the reclosing and the corresponding criteria are proposed.PSCAD simulation analysis shows that the proposed method is correct and effective,helping to improve the success rate of the reclosing applied to the phase-phase faults in the distribution network.