Effect of small hydroelectric generator cluster on power oscillation characteristics of ultra high voltage AC power grid

In order to analyze the cluster effect of massive small hydroelectric generators grouped in an area and to evaluate the risk of forced power oscillation in main grid caused by the weak damping among small hydroelectric generators, taking small hydroelectric generator cluster in Enshi of Hubei province as a research example, we analyzed the low frequency oscillation characteristic of centre China and North China power grid and ultra high voltage (UHV) AC transmission lines when the generator cluster adopted the detailed model. Simulation results show that there is a weak oscillation mode with the damping ratio close to 3% among the small hydroelectric generators in Enshi, and those generators also participate in the oscillation mode leaded by the generators in Three Gorges power plant. Through further simulation, it is verified that the small hydroelectric generator cluster will induce forced power oscillation with amplitude up to hundred MW in main grid in some special cases. Thereby, we used an oscillation spreading figure to analyze the propagation path and the impact of the oscillation. The results show that the oscillation induced by the small hydroelectric generator cluster in Enshi has small influences on the Three Gorges power plant and the UHV power grid. ©, 2015, Gaodianya Jishu/High Voltage Engineering. All right reserved.