Optimal Bidding Strategies for the participation of Aggregators in Energy Flexibility Markets

The increasing penetration of Renewable Energy Sources (RESs), due to the international energy policies and mainly related to the decarbonization process of electricity production, raises several operating issues for power systems, which need “flexibility” in order to guarantee reliable and secure operation. RESs can be considered part of the Distributed Energy Resources (DERs), typi-cally electric power generators connected to the distribution networks, including photovoltaic and wind systems, fuel cells, micro-turbines, etc., as well as energy storage systems. In this perspective, improved operation of the power system can be obtained thanks to a coordinated control of groups of DERs by resorting to “aggregators”, who have also the task of, offering to power sys-tem a “flexibility service” that need to be appropriately remunerated according to market rules. The implementation of the aggregator function requires the development of tools to optimally operate, control and dispatch the DERs to define their overall flexibility as a “market product” under the form of bids. The contribution of the present paper in this field is to propose a new op-timization strategy for flexibility bidding to maximize the profit of the aggregator in flexibility markets. The proposed optimal scheduling procedure accounts for important practical technical aspects related to the DERs’ operation and their flexibility estimation. A case study is also pre-sented and discussed to demonstrate the validity of the method; the results clearly highlight the efficacy of the proposed approach, which show a profit increase of 10% in comparison with the base case without the use of the proposed methodology. It is evident that quantitatively more significant results would be obtained when larger aggregations (more participants) are consid-ered.