CIRED Workshop - Ljubljana, 7-8 June 2018 Paper 205- Paper No 205 Page 1 / 4 MULTI-OBJECTIVE OPTIMIZATION OF ENERGY STORAGE SYSTEM SCHEDULING IN AN ITALIAN LOCAL ENERGY COMMUNITY Susanna MOCCI Gian Giuseppe SOMA University of Cagliari – Italy ABSTRACT Energy Storage Systems are becoming necessary for the upcoming Smart Distribution Systems thanks to the flexibility they introduce in the network operation. Since their costs are still high, optimal planning and management of these devices are crucial to identify specific configurations that can support storage installation. This consideration has motivated a strong interest of the researchers in this field that, however, have separately solved the optimal storage systems location and their optimal schedule. In the paper, a novel Multi-Objective approach is presented, based on the Non-dominated Sorted Genetic Algorithm – II integrated with a real codification that allows joining in a single optimization all the main features of an optimal storage implementation project. The paper is focused on the potential of a Local Energy Community of residential prosumers (with photovoltaic and storage systems) that can support the operation of the distribution system. In particular, pilots selected in the EU project StoRES (Promotion of higher penetration of distributed PV through storage for all) constitutes the Local Energy Community. Application examples are presented to illustrate the algorithm effectiveness. INTRODUCTION Energy storage is finding increased attraction in medium and smaller scale systems. Such expansion is complementary to the wider uptake of intermittent renewable resources, which are likely to present a whole range of new business opportunities for storage systems and their suppliers. Energy Storage System (ESS) can introduce important benefits to the whole electric system: it should be seen as provider of peak-load shaving or load-shifting functionalities or as an operational tool to facilitate efficient usage of electricity. ESS can incentivise end users to engage in demand response by optimising their power consumption as a response to market-reflective end-user prices. It includes all modifications to customers’ electricity consumption patterns that are intended to alter the timing and level of instantaneous demand or total electricity consumption. Placing energy storage devices at the local distribution grid could empower customers to become more active in steering their electricity consumption. The connection and coordination of an increasing number of ESS lead to new challenges for the maximum exploitation of their technical and economic potentials. The paper is focused on the potential of a Local Energy Community (LEC) of residential prosumers (owners of photovoltaic system - PV - and ESS) to support the operation of the distribution system and get the opportunity to manage electricity costs by time-shifting low-priced electricity and by using storage devices to arbitrage in the wholesale market and possibly provide cheaper electricity as a “service” when needed, and to enhance power quality by avoiding supply interruption for customers in case of service outage. In the paper, a Multi Objective optimization procedure is proposed to identify the Pareto set of solutions for a given LEC (fixed in its topology, and including existing PV-ESS with fixed rating, number and locations). The methodology is based on the Non-dominated Sorting Genetic Algorithm – II (NSGA-II), with different objective functions (e.g. voltage profile, power quality, and minimisation of the energy cost or maximization of the self-consumption) [1],[2]. The decision variable is the daily schedule of the energy stored in each device. The optimal scheduling is found by considering the current Regulation, which only allows using energy storage for increasing the self-consumption, and new schemes with storage and generation freely used to offer services to the network with a Micro Grid (MG). ENERGY STORAGE SYSTEMS BENEFITS Whereas the long-term benefits of decentralised storage are the motivation behind the development of the future smart grid, it is actually the short-term benefits that help devise a starting strategy for achieving that goal. In integrating the concept of supply of services from decentralised storage into their investment decisions, DSOs will be encouraged to assess alternative grid asset and system investments more fully. At a time when investment in smarter grids is urgently needed to achieve agreed political targets, this will create an incentive to consider new ways of doing electricity distribution business and the inclusion of emerging technologies. Compared with long-term future services of the smart grid, most important short-term benefits of decentralised electricity storage for distribution system operators involve the following: • Deferring system upgrade costs and replacements by reducing load peaks; • Improving service reliability and stability support where conventional solutions (new power lines or substations) might not be readily available; • Allowing more recovery time for the power system during scheduled or accidental power interruptions;