对地方电网小水电自励磁判断方法的探讨

摘要

结合理论研究和仿真分析，探讨地方电网内小水电自励磁判断方法的合理性。研究发电机甩负荷机电过程对自励磁的影响，发现发电机减速释放功率可能导致系统产生极大的暂态自励磁过电压；研究地方电网内有功负荷对发电机自励磁判据的影响，发现地方电网有功负荷的存在将降低等值串联容抗xc ，使系统更容易满足自励磁条件。最后通过一个仿真实例对提出的观点进行佐证。本研究对含有小电厂的地方电网自励磁的准确判断具有参考借鉴意义。%Theoretical research and simulation analysis are combined to study the rationality of self-excitation judgment method for small hydrogenerator in local grid. Research reveals how the electro-mechanical process of generator’s load shedding influences the self-excitation and finds that the releasing power during rotor deceleration process may cause a extremely high transient self-excitation over voltage;and reveals how active load in local grid affects the self-excitation criterion of generator and finds the local active load will reduce the equivalent series capacitive reactance xc , making the system easier to meet the self-excitation conditions. At last, a simulation example is put forward as an evidence of the views of this paper. These conclusions are meaningful for accurate judgment of self-excitation in load grid containing small hydrogenerators.