Exploring Optimal Control Strategies for Enhanced Grid Frequency Regulation

Grid resources for which discrete power modulation is the only available control mechanism are currently underutilized in addressing the grid frequency regulation problem. Enabling such resources to participate in grid frequency regulation has potential for improving power system stability. This work addresses the problem from two directions. The first approach investigates the optimal discrete pulse input of a controller which injects power into the system with the goal of minimizing the frequency deviation. The input sequence is characterized by three parameters which determine its start-time, end-time, and magnitude. An interior-point optimization algorithm is applied to find the optimal pulse input. Contour and level set plots for fixed values of the pulse magnitude are also examined. The second approach examines an optimal control strategy for minimizing frequency deviation. An optimal control framework for the frequency regulation problem is presented which also includes a discussion of the linearized model. The optimal control problem is solved using a forward-backward sweep method, and a quantization algorithm is used to discretize the solution. The results of the optimal control strategies show a clear potential for discrete power modulation in grid frequency regulation which demonstrates that optimal control is an effective framework for investigating such strategies.