Improved Voltage Oscillation Damping and Tracking of Subgrid of a Hybrid AC/DC Microgrid using Robust Integral Linear Quadratic Gaussian Control

Future grids will consist of many small and large subgrids that will require complex control for grid interaction as well as tracking of operation. This paper presents the design of a robust integral linear quadratic Gaussian (ILQG) controller for damping and tracking control of subgrid voltage of hybrid microgrid. The design of ILQG is carried out by augmenting the subgrid dynamics with an integrator that takes power from the DC bus connecting with AC and PV based DC grid. The subgrid consists of a parallel combination of several uncertain and unknown loads that may produce the voltage oscillation. The performance of ILQG is evaluated for various load dynamics and compared with the LQG, LQR, and integral controller in terms of bandwidth. The robustness of proposed controller is studied by considering a number of uncertainties within subgrid model. Results show that the proposed ILQG controller provides improved robust performance than others.