特高压主变冷却器双电源系统误并列事故分析

Analyze on an Accident of UHV Transformer Cooling Device's Dual Power Control Circuit

分析一起特高压变电站主变冷却器双电源系统误并列事故;指出导致事故的主因是特高压变电站站内和站外电源系统相角差过大,为各电压等级Yd接线变压器相位转换及电网功角带来的固有现象;导致事故的次因为变压器冷却器双电源控制回路中断路器/隔离刀闸位置启动冷却器回路功能设计不合理所致。影响事故的主因无法改进。重点分析了该冷却器控制回路逻辑及存在问题,提出了由断路器/隔离刀闸位置中间继电器接点分别启动两接触器的双电源控制回路改进方案。理论分析及现场试验均证明该方案的可行性。对超/特高压主变压器冷却器双电源切换回路的设计、调试和运行维护有借鉴意义。

This paper analyzed an accident that a UHV transformer cooling device＇ s dual power circuit was mis- takenly shorted. The main reason is the angular phase difference between UHV substation inside and outside power supply was relatively larger, which was caused by transformers＇ connections in different voltage levels and power angle in power grid. The secondary reason is that the transformer cooling device＇ s start-up circuit which was started by breakers and switches state was unreasonable. The main reason of it could not be improved. In addition, logic and problems of the cooling device＇ s power control circuit were analyzed. And improved program, breakers and switches state relay should separately start the two contacts in dual power, was proposed. Theoretical analysis and test both prove that the improved program is feasible. Thus, it may provide reference for designing, debugging, operating and maintaining work of EHV and UHV transformer cooling device＇ s dual power control circuit.