Flexibility Aggregation Perimeter for Ancillary Services in Radial Distribution Systems: An Application

In the evolving scenario of electricity generation and consumption, the flexibility of prosumers can significantly contribute to the management of electricity networks, especially distribution networks. The flexibility useful to Distribution System Operators (DSOs) is strongly local and requires the identification of network buses where flexibility resources useful to the DSO are available. To this end, the concept of flexibility perimeter can be adopted; it is a set of buses such that any group of prosumers operating within it can provide flexibility, while maintaining the security of network operation. Identifying the perimeter for congestion-reducing flexibility in a radial grid is straightforward; not so easy for the flexibility intended for voltage support services, even in a radial grid. In the paper, a method recently proposed in the literature for the identification and evaluation of the perimeters of flexibility is adopted, applied to the case of the DSO's need to acquire flexibility both for issues of congestion and the profile of voltages. The results of two case studies provide an example of the capabilities and benefits of the method.