新型同杆双回线自适应重合闸方案研究

Study of selfadaptive reclosing for parallel lines

提出了新的可用于同杆并架双回线的自适应重合闸方案,并在此基础上给出了新的同杆并架双回线保护配置方案。对于带并联补偿电抗器的输电线路发生瞬时性故障后断开相电压存在拍频现象,电压频率基本为低频分量;发生永久性故障后,断开相电压主要为健全相感应电压,为工频分量。对故障相恢复电压进行步长为20ms的差分,瞬时性故障时差分后的电压幅值较大,而永久性故障差分后电压幅值基本为零。通过比较差分电压的幅值,能很好地区分瞬时和永久性故障。另外,从可靠性出发,提出了幅值判据和相位判据相结合的方案,综合利用了幅值判据和相位判据的优势。新的幅值和相位相结合的判据,能够很好地适用于不带并联电抗器的线路,一端或者两端带并联电抗器的线路。大量EMTP和RTDS数字仿真实验表明该方案具有很强的可行性和工程应用价值。

A new method of selfadaptive reclosing for parallel lines is proposed and a new protection configuration scheme for parallel lines is brought forward. When transient fault occurs in the transmission line with parallel compensating reactor,the beat frequency exists in broken phase voltage. Its frequency is the low frequency component. When permanent fault occurs,the broken phase voltage is mainly the induced voltage by healthy phases. Its frequency is power frequency. 20 ms- step differential of fault phase recovery voltage is used to distinguish transient fault from permanent fault. The calculated voltage amplitude is high for transient fault,while it is zero for permanent fault. In addition to the comparison of the differential voltage amplitude,phase criterion is also used to improve the credibility. The new method is suitable for lines without shunt reactors,as well as lines with shunt reactors at one or two ends. EMTP and RTDS digital simulations show its good feasibility and engineering value.