Expansion Planning of Transmission Network Considering Abundance and Depletion Characteristics of Hydropower-dominated Power System

hydropower is an important renewable resources for building a carbon-neutral power system. With its rapid development in power system, its abundance and depletion characteristic in different season greatly impact the capacity utilization of transmission lines. This paper proposed an expansion planning method for hydropower-dominated power system considering line capacity utilization. Since N-1 security principle should be met when a new transmission line is built in the system, and the line expansion should also take load development into account, a line capacity utilization index is proposed. By using the utilization index as a operation constraint, and capital costs, power plant operation costs, line congestion costs are used as objective function, an optimal transmission line expansion planning model considering the utilization rate in hydropower-dominated power system is formulated. Three cases are studied to verify the proposed method in modified IEEE 24-bus system. The results shown that the proposed optimization model can avoid congestion and satisfy the system security demand with reasonable capital costs in transmission line expansion, the overall costs are minimized using proposed method.