水轮机定子槽对地电位不合格原因分析及处理

Cause analysis and treatment of unqualified ground potential of turbine stator slot

为预防水轮机定子绕组槽放电而出现局部放电现象,本文以某650 MW水轮发电机定子绕组为研究对象,按照3个选定的测试点位,分别测试定子槽总计576跟线棒退槽楔前后槽部线圈防晕层的对地电位,以判断定子线棒的对地电位测试值是否符合要求,并分析不合格的原因。结果表明,退槽楔前后分别有总计283、211槽线棒对地电位超过了《电力设备预防性试验规程》的要求值,退槽楔后的测试合格率比退槽楔前高12.5个百分点,造成不合格率退槽楔前偏高的原因是部分线棒与电子铁心槽壁间出现了空隙和线棒局部半导体漆出现了损坏。提高合格率的办法是改进线棒下线工艺流程及槽电位超标处理工艺流程。水轮机定子槽槽对地电位测试方法和槽楔工艺流程优化对水轮发电机的安全防护具有一定的指导意义。

In order to prevent the partial discharge phenomenon caused by the discharge of the stator winding slot of the turbine,this paper takes the stator winding of a 650MW hydro-generator as the research object,according to the three selected test points,and tests the ground potential of the anti-corona layer of the slot coil before and after the de-slotting wedge of the stator slot with a total of 576 bars,so as to judge whether the test value of the ground potential of the stator bar meets the requirements,and analyze the reasons for the unqualified.The results show that there are a total of 283 and 211 slot bars before and after the slot back wedge,and the ground potential exceeds the required value of the Preventive Test Procedure for Power Equipment.The test qualification rate after the slot back wedge is 12.5 percentage points higher than that before the slot back wedge.The reason for the high unqualified rate before the slot back wedge is that there is a gap between some wire rods and the electronic core slot wall and the local semiconductor paint of the wire rod is damaged.The way to improve the qualified rate is to improve the process flow of the wire rod and the process flow of the tank potential exceeding the standard.The test method of the ground potential of the stator slot wedge of the turbine and the optimization of the process flow of the slot wedge have certain guiding significance for the safety protection of the turbine generator.