Reliability Evaluation Of The Secondary System In Smart Substation

Reliability of the secondary system in smart substation is an important guarantee for the safety and stability of power system. The development of UHV technology and smart grid technology has brought higher requirements to the reliability of the secondary system in smart substation. Therefore, evaluating the secondary system in smart substation and giving the CBM strategy can reduce the accident occurred in power network as soon as ensure the safety. In this paper, the reliability assessment method of the secondary system in smart substation was proposed based on the characteristics of the smart substation technology and combining with the secondary system state information the CBM strategy of the secondary system was analyzed.Based on the data analysis of the secondary system, the two system analysis of the smart substation was divided into the protection system reliability analysis and the reliability analysis of the network performance, and the detailed discussion is carried out from two angles:Firstly, this paper proposed a new way to assess reliability of protection system. Based on the characteristics of smart substation, a monitoring method reflecting the changes of the protection system function in terms of logical nodes was provided. Combined with these indices, a dynamic Markov reliability assessment model was built. In use of the assessment model, the condition-based maintenance requirement was calculated quantitatively. A typical 220 kV smart substation was regarded as the example object to illustrate the application method of the assessment model. The result shows that the method can possess certain operability and reflect the characteristics of smart substation protection systems.Secondly, the performance reliability of substation communication network was analyzed, and the uncertain factors are analyzed based on the time delay model of communication network. Based on the information modeling method based on leaky bucket, the upper bound of the communication delay was analyzed, and the end-to-end delay bound of three kinds of information flow was calculated. Dijkstra algorithm was used to find the path between the source node and the destination node, which was used as the transmission path of the information flow. Based on this, the reliability assessment model was established, which was based on the network delay bound and the real time delay of the network.Finally, based on previous analysis, combined with the status of the secondary system state data of intelligent substation, the secondary system state evaluation index system was constructed, and the core evaluation standard was established. The secondary system state input data was directly converted into the evaluation model, and the fuzzy comprehensive evaluation model was established for the two aspects of the system, the protection system, the communication network and the secondary system. Thus the strategy of the condition based maintenance in the secondary system was given.