Control Method for Additional Damper in Hydro-turbine Speed Governor of Hydro-dominant Power Systems

With the rapid development of the national inter-connected power grid, fast automatic excitation regulators and fast turbine governors are being widely used. In the current systems, some power plants adjust their responses for turbine governor systems to a very sensitive level to meet the primary frequency regulation assessment index, which actively brings about negative damping. Under these circumstances, the ultra-low frequency oscillation (ULFO) phenomenon emerged in hydro-dominant power systems. In order to solve the problem of ULFO, the hydro-turbine governor additional damper (GAD) based on phase compensation, which adapts to ULFO, is developed. The design of the control system is relatively simple. As a phase compensation based on the field testing and modeling of the turbine governor, GAD can provide the power system with positive damping, which contributes to the stability and security of the system. According to the impact of the mechanism of the turbine governor on the dynamic stability of the power system and the research of modeling and parametric testing, the proposed method not only supports positive damping, but also eliminates the negative damping of the speed governing system, which can significantly suppress the ultralow frequency oscillation and make it feasible to configure the GAD parameters according to field testing.