Frequency Regulation in AC Microgrid using Sliding Mode Control Strategy

The AC microgrid is equivalent to a synchronous machine and generally connected to several distribution generations (DGs) such as wind, solar, tidal, hydro etc. through power electronic devices known as inverter. This mixed type of structure has led to lack of inertia of the AC microgrid. However, this leads to increase deviation in frequency, rate of change of frequency, as a results, overall stability is more sensitive towards disturbance. Hence, the sliding mode control scheme is developed to provide a frequency support for the inverter based connected DGs in AC microgrid. The deviations in state trajectories guarantee to minimize the negative impact of inertia deficiency on AC microgrid state trajectories. In addition, proposed law performance in terms of trajectories and static error indices compares with linear quadratic regulator method. It achieves minimum time characteristics simultaneously such as over/undershoot, settling time even in presence of load vulnerabilities. The proposed control law is demonstrated using MATLAB simulation.