With the widespread integration of electric vehicles as flexible resources on the user side and distributed photovoltaic generation units into the distribution network, serious issues such as voltage violations and line flow congestion may arise. These problems can severely impact the normal and stable operation of the distribution system, posing significant challenges for distribution system operators (DSOs). To address this, this paper proposes a user-side electric vehicle regulation and local flexibility market clearing method for congestion management in distribution networks. Firstly, the operational mechanism of the local flexibility market (LFM) is established, and a flexibility bidding strategy model for flexibility aggregators is constructed to bid for flexibility based on the flexibility demand published by the LFM. Secondly, based on the alternating direction method of multipliers (ADMM) distributed clearing algorithm, the clearing of the LFM is ensured without disclosing the privacy information of DSOs and user-side flexible resources to the LFM operator. Finally, through case studies, the effectiveness of the proposed LFM mechanism and distributed clearing algorithm is verified, demonstrating that the proposed method can fully utilize the flexibility of user-side electric vehicles for congestion management in distribution networks.

Existing distribution system security region (DSSR) and total supply capability (TSC) are under N - 1 security. This paper proposes definition, model, and application of security region and power supply capability for active distribution networks under normal operational state (N - 0 security). DSSR and TSC under N - 0 security are named as DSSR0 and TSC0, respectively. First, motivation to study DSSR0 and TSC0 is clarified. Then, definitions and mathematical models of DSSR0 and TSC0 are introduced for active distribution networks and flexible distribution networks with soft open points. DSSR0 is the set of all operating points satisfying normal operational constraints and describes maximum allowable operating range of distribution network. All operating points inside DSSR0 are secure, while all operating points outside DSSR0 are insecure. TSC0 is maximum load supply capability that satisfies normal operational constraints of a distribution network, and its connotation is the same as loadability. TSC0 curve is an extension of TSC0. It is composed of total load of boundary points in ascending order and describes complete power supply capability of a distribution network. Next, for urban distribution network with distributed generation in China, the analytical algorithm of DSSR0 and TSC0 is proposed. Furthermore, a drawing method of the TSC0 curve is proposed. Meanwhile, effectiveness and scalability of the proposed method are verified by IEEE RBTS BUS4 case and the modified IEEE RBTS case. Differences in security region and power supply capability between N - 0 and N - 1 security are analyzed. Finally, application cases in both operation and planning are demonstrated. The proposed DSSR0 and TSC0 can help dispatchers obtain feasible operational boundaries, which is the “bottom line” for operation of a distribution network.

This paper proposes a security region of transportation networks, which is defined as the set of flow states (operating points) satisfying the N-1 security in transportation networks. The boundary of the set is closed, inside all the operating points are N-1 secure; oppositely, outside all the operating points are insecure. First, N-1 security of the transportation networks is defined, which means that when a road is blocked, vehicles on other roads within the networks can also reach their destination through different paths without being trapped on the road. Then, the security region of transportation networks is modeled. The algorithm of a boundary calculation is studied and the boundary equations of security distances are proposed. Finally, the proposed security of the transportation networks is presented in different examples. This paper demonstrates the following: 1) the security region can be accurately predicted by the simulation of N-1; 2) the boundary distance can show the necessary degree of security; 3) security can be improved by a preventive control scheme. The simulation on TransCAD is used to verify the correctness of the results.