并联电抗器中性点小电抗的选择及其对单相自适应重合闸的影响

根据单端带并补的输电线路模型,推导了最佳中性点电抗器的取值,以达到对相间电容进行完全补偿并在瞬时性故障时快速熄弧的目的。同时,建立了线路瞬时性故障时的一、二次电弧模型,并在ATP/EMTP中进行了500 kV输电线路瞬时性故障的仿真,仿真包括了输电线路进行导线换位和不换位2种情况,明确了不同中性点电抗器的选择对熄弧时间、潜供电流、恢复电压的影响。由仿真分析发现了传统基于电压幅值、电压畸变的单相自适应重合闸判据的不足。指出自适应重合闸判据应适应线路导线有无换位、有无并补、有无中性点电抗器及中性点电抗器取值大小等情况,从而达到在瞬时性故障时断路器在最佳时间快速重合、永久性故障时不重合的目的。

Influence of neutral reactor on single-phase adaptive reclose

Based on the model of single terminal transmission line with shunt reactors,the optimal value of neutral reactor is deduced,in order to completely compensate for the phase-to-phase capacitance and to rapidly blow out arc under transient fault.Meanwhile,primary and secondary electric arc models under transient fault are established,and the 500 kV transmission line’s transient fault is simulated with ATP/EMTP,which includes two situations of the transmission line,i.e.conductor transposition and non-transposition.The influences of the selection of different neutral reactors on arc extinction time,secondary arc current and recovery voltage are specified.The defects of the traditional criterion for single-phase adaptive reclosing based on voltage amplitude and voltage distortion are discovered according to the simulation analysis.It’s pointed that the criterion for single-phase adaptive reclosing should meet some conditions,including whether line conductor is transposed,whether there is a shunt compensator and neutral reactor,and what value the neutral reactor should be assigned.As a result,the breaker would reclose rapidly at the best time under transient fault,while not reclose under permanent fault.