High voltage research of the isolated hydropower islands

As export power network, it is easy to come into the problem of abnormal over-voltage for hydropower station group if there is a large disturbance, which results in the islanding between transmission network and hydropower station group. The paper presents the problem of abnormal over-voltage in isolated system of hydropower station group, analyzes the cause of the problem, and discusses the probability and validity of the use of generator´s leading phase operation to control the voltage of isolated system. Finally, a method is proposed on how to use the capacity of generator´s leading phase operation reasonably and adequately.