论大型发电机微机主保护设计的科学性

迄今大型发电机内部短路主保护习惯配置1或2套纵差保护，并以机端两相短路校验其灵敏系数Ksen,，当Ksen≥2．0时就认为设计性能合格，它能不能对定子绕组短路起保护作用。设计者心中无数，文中以1台540槽水轮发电机可能发生的内部故障类型说明上述做法在运行上存在严重后果，另一种习惯做法是对不同型号的发电机（特别水轮发电机），只要容量相当，不问定子绕组的实际空间布置和结构上的不同，就相互照搬主保护配置主案；通过2台相同容量，不同定子槽数和绕组连接的发电机应采用不同的主保护配置方案，说明上述相互照搬的设计方法是不科学的，并指出关键的问题是正确计算定子绕组内部短路电流。

On the Scientific Design of Microcomputer-Based Main Protection for Large Generator

Until now,the main protection for S/C in a large generator is habitually configured with one or two sets of longitudinal differential relay, and its sensitivity is checked by the S/C current at generator terminal.If the sensitive coefficient is not less than 2 0,its designed characteristic is considered qualified.However,its S/C protection function for generator is not assured to designer.A large hydro generator with 540 slots is applied to explain that the above design method may lead to harmful results in operation.Another popular practice is that different types of generators (particularly hydro generators)with similar capacity use the same disposition of main protection.Two large hydro generators similar in capacity but different in both winding construction and connection are taken to explain that different main protection schemes should be applied and the above design method is unscientific.The key is to properly calculate the S/C current of stator winding.