Facing the scourge of dimensionality and the huge computational burden of AC power flow

the analysis of cascading failure is extensively researched as a remedy. However

owing to its neglect of the nonlinear factors

not only are errors uncontrollable

they steadily accumulate with the cascading failure seriously hampering its application. To enable power flow calculation to possess both the rapidity of distribution factor (DF) and the accuracy of AC power flow

based on the second-order sensitivity to monitoring the error obtained from perturbation

the credibility index of the DF is presented. When the index is over the threshold

AC power flow should be selected instead of DFs to eliminate the accumulated error. Then

a fast calculation algorithm is proposed to balance the accuracy and efficiency in cascading failure analysis. Simulation results show that computation errors can be evaluated by the index

and the computation efficiency is greatly enhanced while the accuracy is guaranteed. This work is supported by National Basic Research Program of China (973 Program) (No. 2013CB228204)

Australian Research Council Project (No. DP120101345)

NSFC-EPSRC Collaborative Project (No. NSFC-513111025-2013

No. EPSRC-EP/L001063/1)

and State Grid Corporation of China.