A control method of an additional damper for hydro turbine speed governor system in hydro-dominant power system

Abstract

With the rapid development of the national inter-connected power grid, the fast automatic excitation regulators and fast turbine governor have been widely used. In the current system, some power plants adjust the response of turbine governor system to a very sensitive level to meet the primary frequency regulation assessment index, which, however, brings the negative damping intensively. Under the circumstances, the ultralow frequency oscillation (ULFO) phenomenon emerged in hydro-dominant power system. In order to solve the problem of ULFO, the hydro-turbine Governor Additional Damper (GAD) based on the phase compensation which adapt to the ULFO is developed. It is improved on the basis of traditional PSS and the design of the control system is relatively simple. As phase compensation based on the field testing and modeling of turbine governor, GAD can provide the power system with the positive damping, which contributes to improving the stability and security of the system. According to the impact of the mechanism of turbine governor on the dynamic stability of the power system and the research of modeling and parametric test, 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 accoraing to field test.