超超临界及超临界机组水内冷发电机定子线圈的绝缘电阻测试

Insulation resistance tests for stator-windings of ultra supercritical and supercritical water-cooled generators

由于发电机汇水管支路多,内径粗,对地绝缘衬垫厚度薄,导致水阻显著降低,测量精度难以保证,现有测试仪的性能和相关规程中的部分参数已不能满足超超临界及超临界机组水内冷发电机定子绕组绝缘电阻测试的要求。分析了超超临界及超临界机组水内冷发电机定子绕组绝缘电阻测试的影响因素和对专用测试仪器的新要求。为适应发电机定子绕组绝缘电阻测试的新要求,专用绝缘电阻测试仪器需要提供更高的测试电压,更大的容量和量程,以及更精确的等电位屏蔽。而从水内冷发电机绝缘电阻测试的模型入手,就不难得到发电机的改进对水电阻的影响,进而得到对上述绝缘电阻测试仪的各项性能参数的影响。

This paper analyzed the influencing factors for testing insulation resistance of stator windings of ultra supercritical and supercritical water cooled generators.The new requirements for the dedicated insulation tester were also discussed.For ultra supercritical and supercritical water cooled generators,there are many water cooling pipes.The inner diameter of the water collecting duct is large and the insulation liner for the water collecting duct is thin.As a result,the insulation resistance of water cooling pipes is significantly low,which makes it difficult to measure the insulation resistance of stator windings.The current tester performance and related rules of the ultra supercritical parameters can not satisfied the requirements for testing insulation resistance of stator windings of ultra supercritical and supercritical water cooled generators.In order to adapt to the new requirements of insulation resistance test,the dedicated insulation tester needs to provide higher test voltage,larger capacity and measurement range,as well as higher accuracy on equal-potential guard.From the insulation-resistance test model for water inner-cooled generators,the influence of generator improvements on the water resistance can be analyzed easily,and the influence on various performance parameters of the insulation resistance tester can be acquired further.