**Optimal Siting and Sizing of Wayside Energy Storage Systems in a D.C. Railway Line**

### **Regina Lamedica 1, Alessandro Ruvio 1,\*, Laura Palagi 2 and Nicola Mortelliti 1**


Received: 22 October 2020; Accepted: 25 November 2020; Published: 27 November 2020

**Abstract:** The paper proposes an optimal siting and sizing methodology to design an energy storage system (ESS) for railway lines. The scope is to maximize the economic benefits. The problem of the optimal siting and sizing of an ESS is addressed and solved by a software developed by the authors using the particle swarm algorithm, whose objective function is based on the net present value (NPV). The railway line, using a standard working day timetable, has been simulated in order to estimate the power flow between the trains finding the siting and sizing of electrical substations and storage systems suitable for the railway network. Numerical simulations have been performed to test the methodology by assuming a new-generation of high-performance trains on a 3 kV direct current (d.c.) railway line. The solution found represents the best choice from an economic point of view and which allows less energy to be taken from the primary network.

**Keywords:** optimization; energy storage system (ESS); siting; sizing; regenerative braking; particle swarm optimization (PSO) algorithm; net present value (NPV); railway network
