水轮发电机调速系统对超低频振荡的影响及模型适用性分析

The risks of extra-low frequency oscillation related to hydro-electric governor system commonly exit in power grid with high proportion hydropower. Due to the complicated nonlinearity of hydro-electric prime motor, the parameter tuning of governor system lacks of sufficient guidelines. This paper demonstrated the effect mechanism on extra-low frequency oscillation caused by hydro generator governor system by establishing transfer function model of governor system and analyzing the phase-frequency characteristics. The characteristic variations of prime motor phase-frequency under different loads and working water heads were studied, finding that operation condition in low water head and high load was the appropriate conservative-condition for frequency stability analysis. Based on the frequency oscillation accident in central Tibet grid, this paper tuned and optimized the governor system parameters adopting the simplified prime motor model in conservative-condition. The operation status in the past three years showed that the optimized parameters solved the problems of extra-low frequency oscillation in central Tibet grid. This study has directive significance for similar governor parameter tuning.