Distributed optimisation-based collaborative security-constrained transmission expansion planning for multi-regional systems

This study presents a distributed collaborative transmission expansion planning (TEP) algorithm for interconnected multi-regional power systems. The proposed algorithm is a multi-agent-based TEP. A local TEP is formulated for each region (agent) with respect to the region\u27s local characteristic and interactions (i.e. tie-line flows) with its neighbours. Nodal power balances at border buses are modified to model the interactions. Realistic planning constraints and objectives such as budget constraints, operational costs, N − 1 security criterion, and uncertainties are modelled in the local TEPs. The information privacy is respected as each local planner needs to share limited information related to cross-border tie lines with other planners. To coordinate the local planners, a two-level distributed optimisation algorithm is proposed based on the concept of analytical target cascading (ATC) for multidisciplinary design optimisation. While the upper level solves the local TEPs in parallel, the lower level seeks to coordinate neighbouring regions. The lower-level problem is further replaced in the upper-level optimisation by Karush-Kuhn-Tucker conditions to relax the need for any form of central coordinator. This makes the proposed ATC-based TEP a fully parallelised distributed optimisation algorithm. An initialisation strategy is suggested to enhance the performance of the distributed TEP