Robust PI controller design for frequency stabilisation in a hybrid microgrid system considering parameter uncertainties and communication time delay

Abstract

One of the major issues in the operation of an islanded microgrid is the frequency deviations caused by the variation of power production coming from non-dispatchable renewable energy sources. Using an appropriate control system may allow the system to deal with the frequency deviation and allow the system frequency to be restored to its rated value. A wide-area system frequency controller sends a control signal to each of the dispatchable generating sources to enforce the frequency control by using communication channels. However, the communication channels are susceptible to the time delays, which affect the performance of the frequency control system and potentially the system security. Also, the system parameters are uncertain due to the error in the modelling, variation in network topology, generations, loads etc. This study proposes a robust proportional and integral (PI) system frequency controller based on Kharitonov theorem (KT) considering the time delay of the communication system and the system parametric uncertainties. Simulation results demonstrate that the KT-based controller model has enhanced robustness compared to the conventional approaches of controller design.