Mitigation of Grid Congestion by Curtailment of Thermal Generators and Renewable Energies Based on Sensitivity Analysis

Abstract

Grid congestion is expected owing to the interconnection of massive renewable energies within the transmission system. Power system operators need to resolve the problem by controlling the output of thermal and renewable generators, such as curtailment, which should be the smallest possible for efficient utilization. Moreover, the equality of generation opportunities should be maintained among renewable energies. However, achieving the two objectives simultaneously is challenging, because the output curtailment effect on grid congestion in a loop system varies depending on its configuration. Further, the thermal generators are curtailed before renewable energies in the merit order scheme necessitating adjustments in the thermal generator output considering the renewable energy curtailment. This study proposed a method to determine the output curtailment ratio of thermal power and renewable energies employing sensitivity analysis, aiming to ensure equality, and maximize the power generation opportunities of renewable energies for the mitigation of grid congestion. The effectiveness of the proposed method was verified via numerical simulations using a power system model based on an actual power system in the northern Tohoku area of Japan. The results indicate that the proposed method can reduce the total amount of curtailment and improve the equality of generation opportunities.