Characterization of Energy Storage Sytems for Renewable Generators: An Experimental Testbed

The increasing presence of Distributed Energy Resources (DERs) in distribution grids is posing relevant challenges to all electricity operators, particularly concerning the unreliability and intermittency of distributed generators based on Renewable Energy Sources (RESs). The use of Distributed Energy Storage Systems (DESSs) has been recently proposed to cope with these issues, along with the implementation of advanced Demand Response (DR) programs and of ancillary services within Smart Grids. The test of these advanced (and experimental) mechanisms in an operating distribution grid is not usually feasible, both for economic as well as for technical reasons, including security and safety aspects. Conversely, the test in simulation or in Hardware In the Loop (HIL) environments may be limiting, due to the difficulty in reproducing the typically unpredictable behavior of the power demand patterns of end-users. For this reason, a testing facility for the characterization of DESSs coupled with RES generators has been designed and deployed in the eLUX laboratory of the University of Brescia. The system is formed by a 25 kWh DESS coupled with a 64 kWp photovoltaic power plant. The testing facility has been equipped with an experimental supervisory system which allows the remote monitoring and control of both the power installations. Such a system can be used to test and validate different control approaches, including DR requests and ancillary services, under working conditions similar to the real deployment of DESSs in modern power grids.