Sizing and operation of pumped hydro storage for isolated microgrids

Energy storage has an effective role on establishing isolated microgrids (MGs) that contain intermittent renewable energy sources. Energy storages depending upon their technologies can ensure stable and reliable operation, control, and resiliency of the MGs. Therefore, it is indispensable to study MGs operation using appropriate, cost effective and sustainable energy storages along with necessary control. In this paper, sizing, operation and control of a suitable energy storage method for a case study MG system is presented. Due to the excellent geographical location of the case study MG system, a pumped hydro storage is selected; and the sizing of this storage unit is provided using mathematical models that is based on the system physical dimension. In addition, governor-excitation control based on power-frequency droop is designed for the pumped hydro storage unit. The controller performance is tested under various load changes in the MG and the results are presented to show the effectiveness of the designed controller. The performance of the MG frequency and the voltage at the MG bus under load disturbances indicate that the proposed pumped hydro storage is capable to maintain stable operation of the study MG system. Sizing outcomes and performance analysis of the designed controller have been carried out using MATLAB/Simulink software package.