龙羊峡和拉西瓦水电站多分支发电机主保护设计对比

在吸取国外大型水电站发电机主保护设计成功经验的基础上,龙羊峡水电站在国内首次采用多回路分析法计算发电机内部短路,以校验保护灵敏度,现场运行已证明龙羊峡发电机主保护设计的正确性。随着发电机主保护设计技术的发展,拉西瓦水电站发电机主保护设计则是在全面的内部短路分析计算的基础上,经定量化的设计过程而完成。针对该奇数多分支发电机的故障特点,首先采用相隔引出方式构成不完全裂相横差保护,然后通过合理选择零序电流型横差保护以形成对不完全裂相横差保护性能的补充;差动保护用TPY型电流互感器的正确选型,为上述主保护配置方案优异性能的实现提供了坚实的保障。

Comparison of the Main Protection Designs for Hydro-generators with Multi-branch Per Phase of Longyangxia and Laxiwa Hydropower Stations

By summarizing the successful overseas experience in the design of large-sized hydro-generators,the multi-loop analysis method is applied for the first time to Longyangxia generators to calculate several internal faults for checking protection sensitivity.The validity of the main protection design for Longyangxia generators has been verified by pratical operation.With the development of main protection design technology,the main protection configuration scheme for Laxiwa generators is completed through a quantitative design process,which is based on the complete calculation of possible internal faults in the stator winding.According to the fault feature of the Laxiwa hydro-generator with odd-branch per phase,the incomplete split-phase transverse differential protection should be applied to abandon the fourth branch per phase and the left even branches per phase are reasonably grouped in an alternating mode.The composition of zero-sequence current transverse differential protection is then rationally selected to supplement the protection performance to the incomplete split-phase transverse differential protection without additional hardware investment.The proper selection of TPY current transformers for differential protection contributes to the realization of the above main protection schemes.