Optimal Planning of Distributed Battery Energy Storage Systems in Unbalanced Distribution Networks

The proliferation of distributed renewable generation poses many challenges to power distribution networks (DN), such as network congestion and voltage violations. Recent advances in battery technologies have made battery energy storage systems (BESS) more economically viable than ever before, which makes them suitable for many grid-scale applications. By providing grid support, distributed BESS can serve as enablers for higher penetrations of renewables at the DN. Distributed BESS can also provide ancillary services (AS), such as frequency regulation and reserves, to the bulk power grid. This article proposes a budget-constrained planning model for optimally sizing and siting distributed BESS in a DN to provide grid support for a renewable-rich DN and provide AS to the electricity market. The proposed model, formulated as a mixed-integer linear programming problem, maximizes the total profit of participating in the AS markets while supporting the operation of an unbalanced DN. Simulation results and sensitivity analyses demonstrate the merits of the proposed planning model. The accuracy of the linearized unbalanced DN model is also validated.