Load Frequency Control Of Interconnected Power Grid Based On Differential Games Theory

One of the important goals of power system operation and control is ensure that the system frequency stability. In interconnected power system, when a serious fault occurs in an area which causes that frequency of the system deviates from the normal range, other areas interconnected with the area can provide power support for it through the tie-line. But in the process of mutual support, the areas that provide support may bear additional frequency regulation burden. At present, China’s regional power grid gradually become independent stakeholders, and they want to maintain a stable system frequency, but are unwilling to pay too much price in the process of support. Considering this, the regional frequency regulation strategy formulated should be able to coordinate above issue and keep the regional income balance. Otherwise, some area may change frequency regulation strategy arbitrarily just for the best self-interest. If multiple regions have changed frequency regulation strategy, the system operating point will be transferred to some unknown location, which will harm the security and stability of the grid, and the serious situation is that system splitting and large area blackout may occur.This paper applies the differential games theory to load frequency control of interconnected power grid, establishes a linear quadratic differential games (LQDG) model of four-machine-two-region power system and designs its feedback Nash equilibrium strategy of generators in different areas. Compares control effect and persuasiveness of traditional PI controller, controller based on optimal control theory and controller based on feedback Nash equilibrium. The simulation results show that feedback Nash equilibrium can solve the coordinate problem above and offer a persuasiveness strategy.To prove the feasibility of differential games in frequency control future, this paper establishes a LQDG model of four-machine-two-region power system including energy storage device. Compares control effect of traditional PI controller and controller based on feedback Nash equilibrium when the disturbance continuous. The simulation results show that feedback Nash equilibrium can reduce the frequency fluctuation and recovery to the stead-state value quickly. When continuous disturbance occurs, the feedback Nash equilibrium strategy also can achieve good control effect and proved that it has strong robustness.