Under the target requirements of emission peak and carbon neutralization strategy, the large-scale development and utilization of clean energy such as hydropower is an inevitable trend. However, with the continuous increase of single unit capacity of hydro generator, the capacitance of stator winding to ground also increases, which leads to the problem of neutral point voltage drift caused by the imbalance of three-phase parameters of generator, which poses a serious threat to the safe operation of generator. Therefore, aiming at the phenomenon of neutral point voltage drift of hydro generator, taking the 1000MW hydro generator of Crane beach hydropower station as the research object, this paper puts forward the neutral point voltage drift suppression method of hydro generator, injects zero sequence current into the neutral point of generator, and realizes the suppression of neutral point voltage by controlling the size and phase of current. Theoretical analysis and simulation results show that this method can effectively suppress the neutral point voltage drift of hydro generator, and provide a reference for the research of protection strategy of large hydro generator.

hydro generator; neutral drift; injection current; three-phase unbalance