智能相控断路器在35kV并联电容器投切中的应用

某500 kV变电站利用SF 6断路器投切35 kV并联电容器组时,连续发生2起串联电抗器设备故障,分析原因是在投切操作过程产生了较大的涌流及过电压,引起干式空心电抗器发生匝间短路故障,严重威胁系统的安全运行。为了避免此类故障的再次发生,提出采用适用于投切35 kV并联电容器组的智能相控断路器来抑制合闸涌流,降低分闸重燃概率。为验证智能相控断路器的有效性,首先分析了投切涌流及过电压产生的原因和相控开关技术的原理,然后将智能相控断路器应用于该500 kV变电站的35 kV无功补偿系统,并分别对智能断路器与普通断路器进行多次分合闸对比试验,试验结果表明:普通断路器随机投切电容器组产生的最大涌流为4.2(标幺值,下同),过电压为1.81;智能相控断路器投切电容器组产生的最大涌流为2.3,过电压为1.4。试验结果证实智能相控断路器的应用能够从源头抑制合闸涌流和过电压,提高无功投切效率和系统安全性。

Application of Intelligent Phase-controlled Circuit Breakers in 35kV Switching Shunt Capacitor Banks

When a SF 6 circuit breaker in a 500 kV substation in Shenzhen switched a 35 kV shunt capacitor bank,two cases of equipment faults of series reactors occurred.The reasons were analyzed as large inrush current and over-voltage in the switching process,which caused turn-to-turn short circuit fault of the dry air reactor and seriously threatened safe operation of the system.To avoid such accidents,this paper proposes to use the intelligent phase-controlled circuit breakers to suppress closing inrush current generated in the process of switching 35 kV shunt capacitor banks and reduce the probability of re-ignition.In order to verify effectiveness of the intelligent phase-controlled circuit breaker,the paper firstly analyzes causes of switching inrush current and over-voltage and the principle of phase-controlled suppression technology.Afterwards,it uses the intelligent phase-controlled circuit breaker for the 35 kV reactive power compensation system in a 500 kV substation in Shenzhen,and respectively makes comparative tests for opening and closing of the intelligent circuit breaker and the ordinary circuit breaker.The test results show that the maximum inrush current generated by the conventional circuit breaker random switching capacitor bank is 4.2 p.u.,and over-voltage is 1.81 p.u.The maximum current of the intelligent phase-controlled circuit breaker switching capacitor bank is 2.3 p.u.,and overvoltage is 1.4 p.u.It has confirmed that the phase-controlled circuit breaker can suppress inrush current and over-voltage and improve reactive switching efficiency and system safety.