The Influence of the Ratio of Hydropower Unit Capacity on the Stability of Primary Frequency Regulation of Power Grid

In actual work, the hydro generating units connected to the grid to meet the requirements of primary frequency regulation speed, often adjust the governor parameters bt and Td smaller to improve the speed performance, which makes the stability of the unit unable to be guaranteed. When the capacity of the hydroelectric generating unit is relatively small in the system, the system will not generally have any stability problems. However, when the capacity is relatively large, it may cause instability of the whole system. In order to study this problem, this paper established hydropower and thermal power unit interconnection model, draw the stability domain of the system when the hydropower units take different capacity proportion, and analyze the existence of control parameters (bt,Td) that satisfy the primary frequency regulation speed index, The calculation results show that there is no control parameter (bt,Td) in the stability domain that meets the primary frequency regulation speed index when the capacity of hydropower unit in the system exceeds 84.35%, which neither satisfy speed nor stability at the same time.