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).