Bi-level coordinated operation strategy of an active distribution system with load aggregators

• A bi-level coordinated optimization model for DSO with multiple LAs is constructed. • The bi-level model is transformed into mathematical programming with equilibrium constraints. • DSO can guide LA’s electricity consumption behavior by setting reasonable prices. Load aggregator (LA) is an effective form of managing multiple distributed energy sources on the user side. With the increase of emerging market players such as LAs, it is of great significance to realize the coordinated optimization of multiple entities and improve the whole economy of the distribution system. In this paper, a bi-level coordinated optimization model for distribution system operator (DSO) with multiple LAs is constructed. At the upper level, the DSO participates in the upstream energy market representing its internal load and multiple LAs, considering the power flow constraints of the distribution network. At the lower level, each LA maximizes the consumer surplus. The Karush–Kuhn–Tucker (KKT) condition is used to deal with the lower level and transform the bi-level model into mathematical programming with equilibrium constraints (MPEC). Furthermore, the nonlinear variables in the model are linearized by Fortuny-Amat transformation and strong duality condition. Finally, the MPEC problem is transformed into a single mixed-integer linear programming model. It is indicated that compared with taking LA as a fixed load, DSO can guide the power consumption behavior of LA by setting reasonable prices, ensuring the economic benefits of each LA while improving the economy of the distribution system. The case studies verified the effectiveness of the proposed bi-level scheduling model.