A novel voltage stability and quality index demonstrated on a low voltage distribution network with multifunctional energy storage systems

Abstract

This work examines the effect of energy storage systems (ESSs) operation on the voltage stability and quality of the local power system. The variation of these two voltage dimensions is expressed in a collective manner by the novel voltage stability and quality index (VSQI). For the calculation of the VSQI, a complete voltage stability curve is required, and the coordinates associated with voltage stability and quality are identified. The distance between the abovementioned coordinates, that collectively indicates the effect of ESSs operation on the two voltage dimensions, is represented by the VSQI. The process for VSQI identification is repeated for each operating scenario, with the studied cases including grid operation prior to ESSs utilisation, grid support performed by a community level (CL) ESS, and grid operation with distributed (DIST) ESSs. The ESSs are powered by renewable energy sources (RESs), and a future scenario of 70% photovoltaic (PV) penetration was examined. Other ESSs applications presented in this work, include time-shifting of the energy produced by RESs, peak load shaving, and reducing the loading levels of transmission lines and of the substation transformer. The above stack of ESSs applications, highlights the multifunctional role of ESSs as support to the grid. A real low voltage (LV) distribution network located in south-east Queensland, Australia was employed for the study.