Probabilistic power transmission system reliability evaluation

Abstract

Modern power systems are prudently designed and operated to their brim as allowed by policies and procedures. Many of these utilities have advanced transmission systems built over half a century. With considerable aging transmission asset, their up keep and renewal is very expensive. Probabilistic planning, though computationally cumbersome, is an approach that objectively compares economic risk from aging assets versus cost of upgrades. With a demand for such a generic tool amongst utilities, this thesis presents a probabilistic approach for transmission system expansion planning. The proposed method estimates potential economic losses from aging transmission system assets considering N-1 contingencies where N-1 contingencies represent operation of the transmission system after one element is removed due to fault. Thereafter, the thesis proposes a formulation that computes the best transmission system reinforcement plan to eliminate economic losses from all possible N-1 contingencies. Finally, tests on a sample 7-bus system and IEEE 118-bus system where potential economic losses from N-1 contingencies is compared with transmission system optimal expansion plan are presented. Test results reveal that in certain cases, there is economic merit to upgrade the system and benefit with from a robust transmission system. A 304-bus North American system was also tested and is reported.