Feasible Set Projection Method for Calculating Multi-Line-Coupled ATC

The available transfer capacity (ATC) has been widely used for multi-regional electricity trading to secure the operation of power grid. Conventionally, the ATC is evaluated for each tie-line independently. Due to network constraints of intra-regional system, however, the allowable power flows on different tie-lies are coupled. The independent ATC evaluation of different tie-lines may overestimate the available network capacity and will consequently lead to security issues. To this end, this paper proposes the concept and model of the multi-line-coupled ATC (MLC-ATC), which is defined as the feasible set of tie-line power flows that are secure for all the involved regions simultaneously. A polyhedral projection-based algorithm is developed to calculate the MLC-ATC by identifying the vertices of the feasible set. An inter-regional market clearing model is also established based on the MLC-ATC which enforces operation limits of tie-lines and regional networks simultaneously. Case studies based on a 5-region system validate the effectiveness and superiority of the proposed MLC-ATC model in comparison with the conventional ATC model.