Congestion Management Method of Low-Voltage Active Distribution Networks Based on Distribution Locational Marginal Price

Large-scale distributed energy resources, such as electric vehicles (EVs) asymmetric access to low-voltage distribution systems, may cause security problems, including line congestion, voltage violation, and three-phase unbalance. In this paper, a congestion management method of low-voltage active distribution networks is proposed. The soft open point, a flexible power electronic device, is considered as a direct control means to solve the congestion problem first. A semidefinite programming model based on a symmetrical component method is constructed to optimize the operation strategy that can be efficiently solved to meet the demands of rapid centralized control. To guide the charging behaviors of flexible load represented by EVs, a market mechanism suitable for the low-voltage unbalanced network is further considered. Though linear approximation and sensitivity analysis, a pricing model of flexible load is established accounting for the effect of network loss, voltage variation, voltage three-phase unbalance, and line overload to distribution locational marginal price. Case studies are carried out on the modified IEEE 33-node and IEEE 123-node system to verify the effectiveness and efficiency of the proposed method.