The influence of the UHV transmission line to the TTCs between provincial power grids in CCG

The first 1000 kV ultra high voltage (UHV) AC transmission line in China is being constructed from Shanxi province to Hubei province with 645 km distance, connecting Central China Grid (CCG) and North China Grid (NCG). Total Transfer Capability (TTC) and Available Transfer Capability (ATC) are two main concerns to reliably transfer power between interconnected power grids. This paper investigates the influence of the UHV transmission line to the TTCs between the provincial power grids in CCG with transient stability constraints. The NCG and provincial grids in CCG are modeled by an equivalent single generator system based on the center of inertia (COI) coordinate. Based on different operation condition of the UHV transmission line continuous load flow method, TTCs between the provincial grids in CCG are calculated. Results show that there is notable change of the values of the TTCs with the operation of the UHV transmission line. A detailed NCG-CCG interconnected power grid model is setup by using the Power System Analyze Software Package (PSASP) and the equivalent three- generator system (ETS) method is validated.