Load Frequency Control of an Isolated Microgrid Using Proportional Integral Derivative-Sliding Mode Control

In this paper, a proportional integral derivative (PID) sliding surface based sliding mode control (SMC) technique is proposed for regulating the load frequency of a power system with a standalone microgrid. The key objective is to address the issues of frequency deviation in response to variations in load disturbance and wind turbine generator (WTG) random power fluctuations. Firstly, we have developed a linear state-space model of a typical isolated microgrid with distributed energy resources (DER) like wind turbine generators (WTG), fuel cells (FC), and battery energy storage systems (BESS). Then a linear quadratic regulator (LQR) controller was employed to compare with PID-SMC. Furthermore, the effect of load fluctuations on the microgrid's frequency control ability is assessed. Also, It has been demonstrated that the closed-loop responses achieved by the proposed PID-SMC is faster as well as flexible for output power deviation of individual microgrid components (turbine, BESS, and FC). Lastly, the frequency control performance of the microgrid has been analysed again under the influence of both random wind power variation and prior variable load disturbance. The superiority of the proposed PID-SMC than the LQR controller is proved by the simulation (MATLAB) results in terms of frequency deviation, overshoot, and undershoot.