Development of Grid-Flexibility Services from Aggregators a Clustering Algorithm for Deploying Flexible DERs

Increasing penetration of Distributed Energy Resources (DERs) will reshape distribution networks in the near future. The Distribution System Operator (DSO) is expected to explore the distribution-level flexibility potential, for tackling grid problems such as congestions, voltage limit violations and unbalancing. The aggregator is also emerging as a new intermediary between the small-scale DERs and the electricity system: flexibility services can be beneficial for different stakeholders such as DSOs, Transmission System Operators (TSOs) and Balance Responsible Parties (BRPs). In this paper, a procedure for DSO-aggregator interaction is specified to procure flexibility in the intra-day planning in order to solve grid problems. Specifically, a clustering algorithm has also been proposed as a decision-support tool for the aggregator to select the most effective group of resources to provide grid-flexibility services. A simulation case study in IEEE LV European Test Feeder involving electric vehicles, heat pumps and smart appliances has been set to solve overloading at the transformer level. The results show that the procedure can solve approximately 90% of the problems, depending on the availability and time-of-use restrictions of the flexible resources.