大型发电机组注入式定子接地保护调试与整定

随着发电机单机容量的不断增大,发电机定子绕组对地电容不断增加,导致定子单相接地电流不断增大,容易造成发电机定子对地绝缘老化或出现接地故障,对发电机定子单相接地保护提出了更高的要求以确保发电机安全运行。阐述了注入式定子接地保护原理及现场调试方法,并对相角补偿值、阻抗补偿值及对相关的保护值进行了整定。根据现场对发电机静止状态下的调试以及发电机由空载缓慢升压至30%额定电压后的测试结果,进一步验证了保护定值整定的正确性和保护装置动作的准确性。

Commissioning and Setting of Voltage-Injection Stator Ground Fault Protection for Large-sized Generator

Generator capacity and stator winding capacity to ground per phase increasing cause large current circulating within the stator, which may result in severe damage to the stator insulation and earth faults in the stator. So higher requirements are needed for stator single-phase grounding protection of large generator.The paper introduces the basic principle of voltage-injection stator single-phase grounding protection and summarizes the field adjustment methods of the voltage injection scheme against the stator earth fault protection ,and gives the experimental results of adopting impedance angle mutation and transition resistance.The actual operating status for inoperative generator and that with 30% rated voltage commissioning are analyzed, and the results have verified the accuracy of setting the grounding transition resistance and selecting the fault generator.