A DC network equivalent for adequacy evaluation of interconnected systems

Abstract

This paper presents a DC equivalent network for the approximation of interconnected systems in the adequacy evaluation of the system under consideration. The equivalent network is built by parallel connecting all source buses to obtain a single source bus. The network constructed in such a way is than transformed in an equivalent network containing only equivalent source bus and the interconnection buses to the system under investigation. The number of relevant states of the equivalent source is constrained to these that provide the emergency support to the neighboring system not exceeding the agreed value or the total loading capacity of the interconnection lines. The contingencies in the approximated system associated with transmission line outages are modeled by a single equivalent source state and by modifying the admittances of the equivalent network in accordance with the probabilities of these contingencies. The equivalent network formed in such a way has a simple structure and a reduced number of states when compared to the original network, which considerably reduces the computational burden in the evaluation of the adequacy of the system under consideration. The application of the proposed model is demonstrated on two well-known systems.