(1. China Electric Power Research Institute (Nanjing), Nanjing 210003, China; 2. College of Energy and Electrical Engineering, Hohai University, Nanjing 210098, China; 3. State Grid Electric Power Trading Center, Beijing 100031, China)

Trans-regional and trans-provincial electricity transactions are an important means to realizing large scope of electric energy resources optimization configuration. With the development of ultra-high voltage(UHV)power grid, power grid structure is getting increasingly complicated than ever before, posing challenges to path optimization of trans-regional and trans-provincial electricity transactions. The network flow theory is introduced into the mid-and long-term trans-regional and trans-provincial electricity transactions. The traditional network flow method and the expanded network flow method are put forward, respectively. The optimization model takes maximum social welfare as the objective, while considering the transmission channel capacity and transmission loss constraints. Finally, by using the simplified transmission structure in the country, two different path optimization modeling methods are verified and comparatively analyzed. The results show that the expanded network flow method is even better in achieving path optimization in complicated grid structure and solving concurrent problem while forming an integral path, providing a new line of thought to optimization of complicated path for large-scale trans-regional and trans-provincial electricity transactions. This work is supported by State Grid Corporation of China (No. DZN17201300045).