Real-Time Load Frequency Control for an Isolated Microgrid System

Microgrids are small power grids with distinct operation characteristics; they can operate either independently or connected to larger grids, and usually a significant proportion of their generation capacity is comprised from intermittent resources such as solar and wind power generations. Power grids, in general, must operate such that the power generation and power demand are balanced at all times. Such balance is attained by implementing a Load Frequency Control (LFC) mechanism. The goal of LFC in a microgrid system is to maintain the system's frequency within acceptable limits around nominal value under various conditions, such as fluctuating power demand and/or contingency situation such as unexpected loss of one or more of the system's generating units, in order to ensure system's stable operation. In case of small and isolated microgrid systems, however, the stability of the microgrid system is an issue of much greater significance as there are no means of connecting to primary grid power. The objective of this thesis is to design a Load Frequency Control (LFC) mechanism using Battery Storage System (BSS) and Diesel Generation (DG) units for an isolated microgrid system. The microgrid system under consideration is comprised from two DG units, a BSS unit, and two solar panels. The proposed LFC mechanism is implemented in a decentralized fashion. It was tested under different operation conditions; fluctuating power demand which represents the normal operation of power systems, and emergency situations where one of the system's generation units was lost in each case. Results show that the proposed control systems were robust and successful to regulate the system's frequency under all conditions. The microgrid model as well as the proposed control strategy is developed within the Simulink and SimPowerSystems environments.