Impacts of RPS and FIT on inter-regional power transmission line layout in China: Considerations of high renewable energy penetration

Given China's severely separated renewable energy (RE) supply area and load area, the power transmission capacity across regions restricts RE penetration and is directly affected by RE-related support policies. Thus, a multi-objective optimization model is developed to explore the impacts of changes in renewable portfolio standard (RPS) and feed-in tariff (FIT) policies on the optimal transmission line layout. The model regards the maximization of RE power grid-on and minimization of the total cost for the optimal line layout, transmission capacity, and technology selection. We found that power transmission in "West-to-East" and "North-to-South" is strengthened, with the capacity expected to expand 2.2 times between 2020 and 2040. 2024–2026 is the period with the most new lines. The new line grows when the RPS target increase. Compared with the business-as-usual scenario, in the two scenarios where RPS increased by 10% and 15%, the newly built lines' number could grow by 35% and 21%, respectively. On the contrary, if the FIT subsidy continues beyond 2020, the demand for new line construction may decrease, reducing 480 TWh (FIT2025) and 330 TWh (FIT2040) of RE power on-grid. Further, the penetration proportion of renewable generation could be 55.8%–61.8% in 2040, achieving high penetration of RE in China.