断路器均压电容对空载变压器选相关合的影响

Influence of Breaker’s Grading Capacitor on Controlled Switching for Unloaded Transformer

选相关合是一种抑制空载变压器励磁涌流的有效措施,剩磁测量是实现空载变压器选相关合的关键,主要研究了断路器均压电容对空载变压器选相关合的影响。首先,通过理论分析发现,使用装设均压电容的断路器切除变压器后,变压器铁心剩磁为周期性的动态值,而不是通常认为的稳定值;其次,对断路器均压电容对变压器铁心剩磁的影响进行了仿真分析和实验研究,仿真和实验结果表明：剩磁水平随均压电容的增大而降低。最后,提出以动态剩磁整周期内的平均值作为剩磁水平,来确定最佳合闸相位进行选相关合的策略,仿真和实验结果验证了其有效性。研究结果对于空载变压器的选相关合具有一定的指导意义。

Controlled switching is an effective measure to suppress inrush current of unloaded transformer, and measurement of residual flux is the key to realize controlled unloaded transformer switching. In this paper, influence of circuit breaker＇s grading capacitor on controlled switching for unloaded transformer is studied. Firstly, theoretical analysis shows that the residual flux in transformer core is a periodic dynamic value rather than a steady value as general think, after the transformer is switched with a circuit breaker equipped with grading capacitor. Secondly, simulation analysis and experiment research on the influence of circuit breaker＇s grading capacitor on the residual flux in transformer core are conducted. Results demonstrate that a larger grading capacitor decreases residual flux level. Finally, a controlled switching strategy is proposed, taking average value of dynamic residual flux during full period as the residual flux level to determine optimal energization instant. Simulation and experimental results validate its effectiveness. The research results are constructive to controlled unloaded transformer switching.