Qualification and Disqualification of Aggregator’s Energy and Ancillary Service Awards in Wholesale Markets

The burgeoning penetration of distributed energy resources (DERs) can pose challenges to the secure operation of transmission and Distribution Systems (DSs). In this paper, using statistical information obtained from different DS conditions and data-mining algorithms, an Independent System Operator-DS Operator-DER Aggregator (ISO-DSO-DERA) coordination framework is proposed, which allows DER aggregators to participate in the wholesale electric market considering DS limits. The performance of this framework is compared with the case where the ISO has no visibility over the DS limits while making decisions on the aggregator’s energy and ancillary service awards. A detailed unbalanced AC optimal power flow based on the current and voltage (IVACOPF) model is utilized for emulating DSO-DERAs coordinated operations to manage DS limits while considering DERAs promised services to ISO. The effect of VAr support capability of roof-top PV unit smart inverters (SIs) is evaluated in increasing the DS flexibility to improve the deployability of the aggregators promised awards. The VAr capability of PV SIs is based on the IEEE 1547-2018 standard, formulated by mixed-integer linear constraints. An IEEE 118-bus system and unbalanced 240-bus distribution test system are used to compare performance of the different ISO-DSO-DERA coordination architectures and, transmission and distribution management during uncertain events.