Power System Cascading Outages Risk Assessment Considering Failure of Control Actions

Abstract

In traditional risk assessment method, failure of control actions is always neglected due to its low occurrence probability. However, failure of control actions usually leads to power system cascading outages, where severe consequence has an impact on risk assessment results. Hence, it is necessary to consider control actions failure in power system risk assessment. In this paper, relay protection failure is chosen as an example of control actions failure and considered in power system risk assessment. In the risk assessment procedure, the probability evaluation of relay protection failure and system risk computation method are concerned. Firstly, a method for relay protection failure probability evaluation is presented, where intrinsic property and operating state of relay protection devices are combined. Secondly, an improved state space partitioning (SSP) method, suitable for relay protection failure involved power system cascading outages risk assessment, is put forward. The improved SSP method transforms sampling strategy of sampling process in common SSP method, utilizing enumerated state help low-probability event sampling. It enables to avoid the low-efficiency problem caused by extreme low-probability event in common SSP method based risk assessment. Finally, relay protection failure probability evaluation method and the improved SSP method are validated with simulations and results show effectiveness in risk assessment accuracy and efficiency.