A two-level hybrid control strategy to augment transient stability and tracking accuracy of hybrid microgrid coupled with industrial loads

Abstract

The hybrid microgrid (HMG) is an arrangement for empowering the society by using the renewable energy sources (RESs) connected with common DC bus terminal. The effective operation of the HMG relies on the transient response of the DC bus as well as the stability of the system state that may change due to the stochastic behavior of RESs and industrial loads. This work is motivated to develop a two-level decentralized control strategy consisting of a non-linear and linear control scheme to augment the transient stability and tracking performance of an HMG. Firstly, a non-linear partial feedback linearization control framework combined with a PI regulator (PFLC-PI) is designed for the transient stability enhancement of the common bus. Secondly, a linear unified controller (UC) is developed to guarantee the constant load voltages over the industrial loads through the control of the load-side inverter. The UC effectiveness is measured by varying the load parameters associated with single- and three-phase load networks. The obtained results are then compared with the existing controllers to guarantee the augmented performance of proposed two-level controller. Additionally, an external parametric uncertainty is intentionally added to the single-phase load network dynamics and studied to ensure the robustness of the controller.