冷却方式对抽水蓄能机组定子绝缘特性的影响

抽水蓄能机组中,发电-电动机具有频繁起停、负荷变化剧烈的特点。近年来其大容量、高水头发展进程使电机频繁负荷变化所产生的热应力对电机安全可靠性的影响越来越不可忽视。热应力不仅与热负荷变化速率、电机结构特征有关,还与发电-电动机的冷却方式直接相关。首先对几种冷却方式应用于发电-电动机中的优缺点进行定性分析,继而提出以对比分析冷却方式对主绝缘冷热循环老化影响为目的的冷热循环实验设计原则,最后通过冷热循环老化实验的形式、以最大局部放电量为绝缘性能的表征参数,定量研究冷却方式对抽水蓄能机组中定子绝缘特性的影响。结果表明,采用蒸发冷却技术的定子线棒抗冷热循环老化性能要明显优于采用通风冷却的定子线棒。

Different Influence of Cooling Method to Stator Bar Insulation Characteristics in Pumped Storage Units

In daily operation of pumped storage station, generator-motor is featured with frequent start up and shut down, sharp operating load change. With the development of higher capacity and water head in recent years, the effects of thermal stress generated in operation load change on pumped storage unit's safety and reliability have become more and more serious. Thermal stress not only has relation with the changing rate of thermal load and structure feature of generator-motor, but also is directly affected by cooling method. Firstly, the advantages and disadvantages of different cooling methods when applying in generator-motor are qualitatively analyzed in this paper. Then the design principle of thermal cycle test is proposed in order to compare the effects of different cooling modes on thermal cycle aging of insulation system. Finally, the maximum partial discharge is used as the representative parameter of the insulation characteristics. Through thermal cycle test, the influence of cooling mode on the insulating characteristics of pumped storage units was analyzed. The experimental results indicate that the anti-aging capability of evaporative cooling stator bar is much better than that of air cooling stator bar.