Robust control of frequency considering operations of AC microgrid in islanded mode

Modelling and control of an autonomous microgrid with both governable and non-governable sources is discussed in this paper. Power sources utilised in microgrid are solar, wind, fuel cell (FC) and diesel-based generator (DG). Batteries, flywheels (FW), and aqua electrolyses (AE) are used as energy storage elements. Recently, due to the increased penetration of non-inertial distributed generations in the microgrid, frequency deviation has become a matter of concern. If the loading conditions and active power generation changes unexpectedly, then the power system frequency would deviate largely. The output of the flywheel, battery, diesel generator, FC, and aqua electrolyser is regulated using the proportional-integral-differential (PID) controller. In this paper, a novel mathematical framework is proposed to tune PID controllers. For zero frequency deviations in steady state, optimum values of proportional, differential, and integral gain coefficients are proposed. The importance of the proposed scheme is to achieve better steady state frequency response.