Congestion Scenarios Screening and Expansion Planning of Transmission Network with High Proportion of Hydropower Considering Capacity Utilization of Transmission Lines

In the hydro-rich areas with high proportion of hydropower in the transmission network, the capacity utilization of transmission lines varies seasonally due to the impact of hydropower abundance and depletion characteristics. Therefore, it is important to investigate the expansion planning method of coordinating the capacity utilization of transmission lines with the system economy. On this basis, an expansion planning method of transmission network with high proportion of hydropower was proposed in this paper by taking into account the capacity utilization of transmission lines. The capacity utilization of transmission lines was used to guide the transmission network expansion planning decision considering the impact of hydropower abundance and depletion characteristics. First of all, the capacity utilization of transmission lines index was proposed by considering the safety margin and development margin. Second, the optimal dispatching model of transmission network with high proportion of hydropower was constructed with the objective of minimizing the generation cost, the penalty cost of load shedding and the penalty cost of hydropower spillage. After that, calculation method of the congestion capacity utilization of transmission lines and the congestion rate of transmission network were proposed. The severe congestion scenarios were identified by calculating the capacity utilization of transmission lines and congestion rate of transmission network under four different operation scenarios: High load during abundant water period, low load during abundant water period, high load during dry water period and low load during dry water period, respectively. Finally, with the objective of minimizing the cost of investing in transmission lines, the operation cost of transmission network, the penalty cost of load shedding and the penalty cost of hydropower spillage, the transmission network expansion planning model with high proportion of hydropower were constructed. Specially, the severe congestion scenarios were incorporated into the transmission network expansion planning model to derive the investment decision of transmission lines. The proposed transmission network expansion planning model was simulated with four cases: Without expansion planning, expansion planning without considering capacity utilization of transmission lines, expansion planning considering capacity utilization of transmission lines, and expansion planning considering higher congestion rate threshold. The simulation results show that the considering of capacity utilization of transmission lines in the transmission network expansion planning with high proportion of hydropower can help reduce blockage and security risk of the system. The effectiveness of the transmission network expansion planning method with high proportion of hydropower considering the capacity utilization of transmission lines is verified. © 2023 Editorial Department of Journal of Sichuan University. All rights reserved.