Evaluation of grid-scale battery energy storage system as an enabler for large-scale renewable energy integration

Abstract

Because of many substantial benefits over other renewable energy resources (RES), photovoltaic (PV) and wind technologies are the most important emerging renewable energy sources (RES) and they are rapidly and widely propagating. However, they are nondispatchable and, the stochastic and intermittent natures of solar irradiation and wind, are some of the fundamental barriers and challenges to their development and their large-scale deployment. As a result, power systems operators have no control over DG’s available resources and are compelled to operate conventional generators to both cater for normal changes in load demand and make provision for DG’s output variations. These concerns lead to increase the uncertainty in power systems operation as they modify both the structure and the operation of the distribution network by affecting inter alia, the voltage profile and stability, the direction of network power flow and the overall performance of the power system. Enabling PV penetration into electrical grids require a balance of supply and demand that cannot be achieved by oneself. Because of the flexibility to control their real power output, batteries are suggested as a suitable and cost effective solution to mitigate the adverse effects of intermittency and shape the fluctuation of the system’s output into relatively constant power. There is a need to quantitatively investigate and evaluate the performance of the use of BESS that adequately smoothen the output of the PV-BESS sub-system for over-voltage reduction and peak load shaving during the high PV generation – low consumption time in lieu of power curtailment or reactive power injection. Using DigSILENT™ - PowerFactory™ this research work investigated the impacts of BESS on voltage stability and power losses with the aim of increasing system loadability and enhancing stability. A modified standard IEEE 9-Bus was used to perform the studies using four cases and various scenarios and the simulation results and comparative analysis first reveal that the combined effect of the Solar PV-BESS system has a substantial positive impact on the system loadability improvement and reduction of the total power system losses. Results further confirmed the BESS’s ability to act as generator, or load, respectively during high load demand/lower PV generation and lower demand//higher Solar PV generation to contribute to the voltage regulation and power system stability, offsetting effectively the intermittency of Solar PV energy sources and subsequently enabling greater RE penetration.