| The protection and control system of smart substation based on IEC61580standard is built on the basis of network communications. Information transmitting through network can achieve a high degree of information sharing, but its real-time performance, security and reliability will affect the effectiveness of the protection and control decisions. Besides, in smart substation, functions of independently relay protection devices are assigned to different IEDs (intelligent electronics device), thus the factors affecting the reliability of protection system is more complex and diversified. Based on these changes, relay protection system of intelligent substation is very different from traditional substation with system architecture and components constitute. Therefore, researches on the reliability of relay protection system of smart substation, including how to accurately the reliability evaluation, find and correct weak spot in the system and improve the reliability of protection, have great theoretical and practical value.Firstly,this paper make a simple introduction for intelligent substation, and analyze the composition of relay protection system of intelligent substation. Then we started with the layer network connection mode of220kV intelligent substation of Guangdong power grid designed by Guodian Nanzi as the model sample, reliability block diagrams of structure that SV and GOOSE packet transmission through different networks in the intelligent substation are established. At last we use the minimal path sets algorithm and disjoint minimal path set algorithm to calculate the reliability of main transformer protection,110kv line protection,220kv line protection and busbar protection. Results show that under the packet transmission through different networks, the line protection and the main transformer protection have higher reliability, but the reliability of busbar protection is very bad.Furthermore, from component level of the relay protection system, this article introduce component importance to analysis and assess the system’s reliability. We choose three indicators including Birnbaum importance, parameter sensitivity and key importance to evaluate the component importance of relay protection system in intelligent substation. From the analysis of the results, Birnbaum importance and parameter sensitivity can help designer find weak component in system and is good for prophase planning and design of the system. The key importance is mainly used for helping maintainer allocate maintenance resources rationally in system operation stage inorder to improve the maintenance efficiency.Finally,directed against the problem of low reliability of busbar protection, this paper take redundant Ethernet technology based on ring network structure to improve the reliability of bus protection. Through simulation and comparison, the results show that reliability of busbar protection have obvious improvement than before.The research of this paper is funded by The National Natural Science Foundation(51377026). |
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