Research and application of overall immunity assessment method for DC commutation failure caused by AC faults

摘要

In this paper, the immunity index for DC commutation failure caused by AC fault (“immunity index” for short) is analyzed on the basis of the three phase maximum grounding impedance (critical impedance). Different from the immune indices that only considered the commutation buses, the immune indices of each AC node are obtained by calculating the three phase maximum grounding impedance. Then the immune indices of each node are clustered by PAM algorithm to automatically identify the weak nodes in power grid. Based on the mean and equilibrium degree of each AC node's immunity evaluation results, this paper proposes weighted form to build the overall evaluation index of immune capability, and the weight can be obtained by the AHP-entropy weight method. Finally, the effectiveness of the proposed overall immunity is verified using a case study. Meanwhile, two long-term planning of a provincial power grid are compared to illustrate the effectiveness and superiority of the proposed method.