基于500 kV长距离电缆线路的合闸过电压研究

Closing Overvoltage Based on EHV Long-Distance Cable Line

相比于传统的架空线路,电缆线路的容升效应明显,使得在超高压时,合闸过电压严重超过规定值,虽然合闸电阻能较好的降低合闸过电压,但因其增加了断路器的机械复杂性,使线路的可靠性降低,应尽量减少合闸电阻的使用,故笔者对不同长度电缆线路的研究表明:对于500 kV的交流系统,当电缆在100 km以内时应采用并联高抗的方式,当电缆在100 km-200 km应采用加装避雷器的方式,当电缆在200 km-300 km时,其他补偿方式不能满足限制合闸过电压的要求,因此应使用合闸电阻的方式来降低合闸过电压。

Compared with the traditional overhead lines, the capacity rise effect of the cable lines is obvious, which makes the switching overvoltage seriously exceed the specified value in the case of ultra-high voltage. Although the switching resistance can reduce the switching overvoltage better, it increases the mechanical complexity of the circuit breaker, which is to reduce the reliability of the lines, and the use of the switching resistance should be reduced as much as possible. Therefore, the author’s research on different lengths of cable lines shows that: for 500 kV AC system, when the cable is within 100 km, the parallel high reactance mode should be adopted, when the cable is within 100 km-200 km, the lightning arrester should be added, and when the cable is within 200 km-300 km, other compensation methods can not meet the requirements of limiting the switching overvoltage, so the switching resistance mode should be used to reduce the switching overvoltage.