Key Transmission Section Identification Method for Large Scale Power Grid with Multiple Faults

The distance for AC and DC dense transmission channels is very long, the transmission capacity is large, and the number of crossing points for 220kV and above are large. Multiple faults are prone to occur in extreme weather, natural disasters and so on, which seriously endangers the security of the power grid. The transmission sections are generally the weak links of power grid, and the rapid search of key transmission sections considering the influence of multiple faults is of great significance to the protection and control of power grid. The current research focuses on the influence of natural disasters on transmission equipment and transmission section search methods such as grid cut search and network contraction. But the impact of multiple faults on security and stability characteristics of power grid and the weak transmission sections haven't been analyzed. In this paper, a key transmission section identification method considering multiple preconceived faults is proposed. Multiple faults are divided into three types, which are multiple AC line faults, multiple DC line faults and AC / DC line mixed faults. And the impact of the multiple faults on power grid security is analyzed. Then, the key section identification method considering multiple fault disturbances and the weak section identification method after topology changes due to multiple faults are studied. The validity of the proposed method is verified in scenarios with multiple expected faults by using AC/DC hybrid power grid data. Identification of critical sections under multiple faults is an important basis for on-line risk early warning and decision-making of multiple faults in large power grid, which has important practical value.