Observer-based distributed control design to coordinate wind generation and energy storage

Higher percentages of wind generation are anticipated to reduce effective inertia on the electric power grid, presenting challenges to electromechanical stability. Two technologies will help mitigate these stability problems: (i) advanced control systems on wind turbines, exploiting Phasor Measurement Units (PMUs), and (ii) deployment of controllable energy storage. This paper extends state feedback-based, centrally-coordinated control design for energy storage and wind generation to consider distributed, observer-based implementations. Establishing that a local bus PMU measurement at each controller is inappropriate, we demonstrate the feasibility of limiting each local controller to a very small set of remote PMU measurements. An approach is developed that characterizes the practical degree of observability achieved on a subspace of lightly damped electromechanical modes of interest. In a representative power system model, the measurement selection methodology and local observer design is shown to yield control performance very closely approximating that obtained in the centralized, full state feedback case.