带并联电抗器的超高压电缆-架空混合线路三相永久性故障识别方法

摘要

The residual voltage characteristics of different two-phase and three-phase faults are analyzed for EHV cable-overhead hybrid line with shunt reactors and a criterion based on the frequency measurements of differential mode voltage is proposed for identifying the interphase faults.After the breakers of both sides are tripped for a fault of hybrid line,the frequency of differential mode voltage is quickly obtained by the extended Prony algorithm,which is slightly below the power frequency for a transient fault while close to zero for a permanent fault.A method based on this property can be easily implemented to distinguish the instantaneous fault from the permanent fault.A lot of EMTDC simulations show that,immune to transition resistance,fault location and cable proportion,the proposed method effectively and reliably distinguishes the instantaneous fault from the permanent fault of EHV cable-overhead hybrid line.%针对带并联电抗器的超高压电缆-架空混合线路,分析了两相或三相不同性质故障时故障相的残余电压特性,提出了基于差模电压频率测量的相间故障性质识别新判据.混合线路发生故障且两侧断路器跳开后,利用扩展Prony算法快速获取差模电压频率.发生瞬时性故障时,差模电压频率略低于工频;发生永久性故障时,差模电压频率接近于0.基于上述特征可进行瞬时性故障与永久性故障的有效识别,该方法原理简单,且易于实现.大量的EMTDC仿真验证表明,该方法能够有效可靠地实现超高压电缆-架空混合线路的永久性故障与瞬时性故障的识别,且不受过渡电阻、故障位置及电力电缆所占线路全长比例的影响.