Effect of flexible ultra-high-voltage power transmission on receiving power systems in China

Abstract

Renewable energy sources are being increasingly adopted in power systems. However, these sources remain intermittent, and power flexibility is urgently required. Phasing out of coal power could potentially result in resource inadequacy and flexibility problems. Ultra-high-voltage (UHV) transmission systems have been used prominently in China for the power distribution of renewable energy. The flexible operation of UHV lines and its effect on production cost and carbon emissions have attracted considerable research attention. In this study, first, we modeled UHV transmission with stable and flexible operations. Next, we integrated the model into a unit commitment and economic dispatch model, which was incorporated into a framework for simulating the operations of a power system. Finally, we used the power system operation simulation tool to compare the two operation modes of UHV on a typical coal-fired power system in Shandong Province. The results of the simulation revealed that in the stable operation scenario, the utilization hours of import power were 332 h lower and the utilization hours of coal-fired units were 134 h higher than those in the flexible operation scenario, whereas carbon emissions were nearly 3% higher than those in flexible operation. The flexible operation mode of UHV can effectively enhance the electricity system’s operational economy and facilitate the decarbonization of future power systems.

Keywords

• UHV transmission lines
• Flexible operation mode
• Transmission characteristics
• Unit commitment
• Power system operation simulation