Medium voltage distribution grid planning considering the flexibility of distributed energy storage

The integration of Battery Energy Storage Systems (BESS) solutions, particularly those connected to the Medium Voltage (MV) and Low Voltage (LV) networks can increase the flexibility of distribution network operation. Compared to conventional reinforcement solutions, BESS integration increases the network capacity to integrate Renewable Energy Sources (RES) and also provides grid support functionalities for congestion management, Volt/Var support and backup capacity. In fact, BESS providing backup capacity can also provide key self-healing functionalities, which will enable the islanding operation of small sections of the distribution network, contributing to improve the resilience and continuity of service in the grid.

This paper provides a long-term assessment of BESS integration in distribution networks, considering two complementary business cases: one where the Distribution System Operator (DSO) operates BESS and another where the consumers in a self-consumption scheme own BESS. A technical and economic analysis was performed for a 20 year planning horizon in order to evaluate the impact of BESS integration in both network congestion and continuity of service, considering its contribution to reduce the Energy Not Distributed (END), during islanding conditions.

In the case of BESS owned by the DSO, a methodology to define the optimal location and sizing of the BESS units on a MV distribution grid was developed, considering two distinct objectives: elimination of overloads and minimization of non-distributed energy, considering the islanding operation of small sections of the distribution network. Then, in order to estimate the degradation of the BESS, the utilization of the BESS systems is determined considering the simulation of its operation. In the case of BESS owned by the consumer in a self-consumption scheme, the objective of the analysis was to quantify the share of consumers with self-consumption profile required to provide the same benefits as the grid owned storage.