Including special protection schemes and operational complexity within transmission planning

Reliability problems encountered within planning studies may typically be corrected either by building new transmission or by installing an SPS. SPS are almost always much less expensive ways to correct reliability problems, since they generally require only relays, communication equipment, computing and associated actuation logic, and tripping devices. However, SPS increase operational complexity due to reasons such as requirement of constant re-evaluation and co-ordination with other protection schemes, difficulty in maintenance scheduling, and serious consequences of mis-operations due to inadvertent interactions. Taking these into account, in this paper a SPS-aided transmission expansion plan is presented with the objective of minimizing production and investment costs, and simultaneously minimizing operational complexity. The proposed planning method uses multi-stage tree approach to enumerate the planning options and Analytical Hierarchical Process to evaluate and prioritize them.