Application and modeling of battery energy storage in power systems

This paper presents engineering experiences from battery energy storage system (BESS) projects that require design and implementation of specialized power conversion systems (a fast-response, automatic power converter and controller). These projects concern areas of generation, transmission, and distribution of electric energy, as well as end-energy user benefits, such as grid frequency regulation, renewable energy smoothing and leveling, energy dispatching and arbitrage, power quality and reliability improvements for connected customers, islanding operations, and smart microgrid applications. In general, a grid level BESS project sends an interconnect request to utility power grids in the project development stage. Simulation models of equipment are then sent for a system impact study (e.g., power flow and/or stability analysis), based on utility grid code requirements. The system study then determines the connection's technical feasibility and impact of the project on the power grid. In this paper, a set of new BESS models is presented that are configured and parameterized for use in system impact studies as well as transmission planning studies. The models, which have been recently approved and released by the U.S. Western Electricity Coordinating Council (WECC), represent the steady state and dynamic performance of the BESS in several software platforms for power system studies based on operating project performance experience. Model benchmarking results as well as a real system case study are also included in the paper to show that the parameterized and tuned models respond correctly and as expected when system operating conditions change following contingency events. Finally, this paper provides useful guidelines in the use of new models to represent a BESS for power system analysis.