Battery energy storage systems in transmission network expansion planning

•Definition of an optimization algorithm to support the network expansion planning.•The algorithm makes a decision about the suitability of a transmission network expansion and the placement of BESS.•The algorithm determines the BESS features that make it convenient in terms of size and price for the expansion planning.•As shown by the results, the inclusion of a storage system allows delaying the construction of some lines in some cases.

To satisfy present or emerging energy demands, the expansion of transmission networks is frequently needed. In conventional approaches, transmission network expansion planning is supported by the construction of new power lines. However, in the general case, expansion cannot be done immediately as the installation of new lines may require facilities and/or authorizations that are not readily available. In this scenario, energy storage systems and batteries in particular may be an alternative since they can reduce the need to procure excess capacity to deal with demand peaks, therefore avoiding unnecessary network expansion. The work in this paper studies the convenience of using this kind of energy system element and what its main features (namely, cost and capacity) should be if positive outcomes are desired. For this purpose, a mathematical formulation for transmission expansion considering energy storage systems in a market-driven environment is presented. It models the impact of new lines and batteries in the transmission network. The proposed framework has been applied to the modified Garver's system and the IEEE 24-bus system. The results show how the deferral of the construction of new lines is feasible if additional batteries are attached to certain nodes.