220kV变电站主变压器中性点接地方式分析

Analysis of Neutral Point Grounding Mode for the Main Transformer of 220 kV Substations

220 kV变电站主变压器中性点接地方式的变化(单变接地方式改为两变接地方式)本质上改变了系统的零序阻抗,需要调整元件状态或保护配合以适应新的方式。对比分析了两种接地方式的各自特点,在此基础上,研究了两变接地方式对断路器遮断容量、短路电流及继电保护定值配合的影响,最后,总结了在方式变更过程中应采取的应对措施,以保证电网的安全稳定运行。

The change of neutral point grounding mode for 220 kV transformer from single transformer grounding mode to two transformers grounding mode,essentially makes an alteration to system zero-sequence impedance. The element status or protection coordination should be changed to adapt to the new mode. By comparison of the characteristics of the two modes,the paper studies the influence of two transformers grounding mode on circuit breaker interrupting capacity, short circuit current and relay settings coordination. Finally,counter measures are summarized for mode changing so as to ensure the safe and stable operation of the grid.