Study on the transmission line vulnerability index and its application based on the transient power angle stability mechanism

In some cases, the weak transmission line is the key to limiting the transmission capacity of a power transmission section. The transmission capability of a weak-connected power system is usually limited by its transient stability limit. Therefore, the weak line identification of the transmission section needs to consider the transient stability impact. Based on the equal area criterion, this paper proposes the identification index of weak transmission lines in two-area power grids. This index can identify weak lines in two-area grids connected by multiple lines in series or in parallel, and it can sort the severity of the faults affecting the weak lines. This indicator takes into account the impact of power flow transferring after a fault and it can directly judge the weak lines of the system and the faults that have serious impact on it under certain conditions without time domain simulation which can save a lot of simulation time. It can be used to calculate the system's transmission capacity and monitor the system's operating status which is of great significance to the system's safety and stability analysis and the transmission capacity calculation.