Study of maintenance strategy of relay protection system based on condition monitoring

With the development of smart substation and monitoring technology, the condition-based maintenance (CBM) can been implemented in relay protection system that once relied on time- or cycle-based preventive maintenance. However, most of the maintenance strategies of relay protection system considering the condition monitoring are studied qualitatively. Based on this, according to the failure mechanism, failure types and evolution features of the components in relay protection system, the factors affecting of health state of the component is assumed to be subject to two failure modes due to degradation and shock. The degradation-threshold (DT) model is used to describe the degradation process and the degradation-shock (DS) model is used to describe the shock process. Moreover, the risk assessment models of relay protection system are established considering the refuse-to-operate failure and the mal-operate failure. The research results are helpful to the implement of CBM for relay protection system in smart substation.