直流真空断路器的新型大电流强迫换流分断方法

Novel High-Current Forced-Commutation Interruption Method for DC Vacuum Circuit Breaker

为提升直流真空断路器的大电流分断可靠性,在典型强迫换流技术的基础上,提出了一种新型的换流分断方案。利用一辅助开关的导通分流作用,通过减小有效换流电流,大幅降低真空断路器熄弧前附近的电流下降率;并在熄弧后,通过该辅助开关的导通电压钳位作用,使真空断路器的暂态恢复电压产生一段低电压区间,从而改善真空间隙的弧后介质恢复特性,实现中、高压直流大电流的可靠分断。同时详细分析了新型换流分断方案的换流过程及其主要影响因素,获得了换流电路杂散电感及辅助开关导通时刻等参数对换流性能的影响规律。最后,开展了快速真空断路器的13 kA换流分断试验,试验过程中熄弧前的电流下降率被有效降低为约55 A/μs、总共持续了约50μs;且在熄弧后约130μs时间内,暂态恢复电压被限制至未超过600 V。试验结果验证了该新型方案的实用性和有效性。

In order to improve the reliability of a DC vacuum circuit breaker(VCB)for high current interruption,a novel current commutation interruption(CCI)scheme was proposed based on the typical forced commutation.The current fall rate before the VCB arc current zero(ACZ)was remarkably reduced by the current shunting of an auxiliary switch conduction and by decreasing the effective commutation current,and an interval of low transient recovery voltage(TRV)came out through the voltage clamping of the auxiliary switch conduction after the VCB ACZ.Thereby,the vacuum gap post-arc dielectric recovery behavior was improved,and the reliable high DC current interruption process would be realized for medium and high voltages.By analyzing the commutation process of the new scheme in detail,the influences of some main parameters,such as the stray inductance of the commutation circuit,the turn-on moment of the auxiliary switch,on the commutation performance and the influence rules were obtained.Finally,the 13 kA CCI test for a fast VCB was carried out.During the test,the VCB current fall rate before ACZ was effectively reduced to about 55 A/μs,which lasted for about 50μs in total.And the VCB TRV was limited to less than 600 V within about 130μs after ACZ.The test results verify the practicability and effectiveness of the new scheme.