移相控制下的特高压直流断路器失灵保护策略

Failure Protection Strategy of UHVDC Circuit Breaker Under Phase Shift Control

对于特高压直流工程,换流器区域故障后采用换流器移相控制有助于故障限流和隔离,但基于电流特征的断路器失灵保护适应性显著降低。为此,在分析断路器在时域、频域的失灵特征的基础上,文中提出了通过电压信号不同频段能量分布进行失灵诊断等研究思路。其次,将完全总体经验模态分解和希尔伯特—黄变换相结合,并在考虑互感器拖尾现象等基础上,提出了一种基于不同频段电压积分值的断路器失灵保护新原理。最后,制定了失灵保护出口后的后续动作策略。仿真验证表明,失灵保护原理满足了速动性和可靠性要求,后续动作策略实现了故障的快速隔离,显著提升了换流器区域保护的性能。

For ultra-high voltage direct current(UHVDC)projects,the use of converter phase-shift control after a fault inside the converter protection zone is helpful for fault current limitation and isolation.Horever,the adaptability of circuit breaker failure protection based on current characteristics is significantly reduced.Therefore,on the basis of analyzing the failure characteristics of circuit breakers in the time and frequency domains,the research idea of failure diagnosis through the energy distribution of voltage signals in different frequency bands is proposed in this paper.Moreover,the complementary ensemble empirical mode decomposition(CEEMD)and Hilbert-Huang transform are combined and,on the basis of considering the tailing phenomenon of the instrument transformer,a kind of new principle of circuit breaker failure protection based on the voltage integral value of different frequency bands is proposed.Finally,the follow-up operation strategy after the failure protection operation is formulated.The simulation verification shows that the failure protection principle has met rapidity and reliability requirement,and the follow-up operation strategy has achieved the rapid isolation of the fault and significantly improved the performance of the converter area protection.