Model-Free H-Infinity Load-Frequency Controller Design for Power Systems

In this paper, an H-infinity load-frequency controller for a power system generator will be designed without the knowledge of the system model. Uncertainty in the system model is a common problem in power systems. In this paper the strategies for discrete-time linear system quadratic zero-sum games related to the H-infinity optimal control problem are solved forward in time without knowing the system dynamical model. The idea is to solve for an action dependent value function Q(x,u,w) of the zero-sum game instead of solving for the state dependent value function V(x) which satisfies a corresponding game algebraic Riccati equation (GARE). The result is model-free approach that solves the zero-sum game forward in time; i.e. it finds an H-infinity controller without knowing the dynamical system. It is proven that the algorithm is equivalent to a model-free iterative algorithm to solve the underlying (GARE) of the linear quadratic discrete-time zero-sum game.