| The trend of towards high-level integration in smart protection brings new potential risks to the reliability of the protection system,and being short of available self-healing technology the extra long recovery time of secondary system under disaster conditions is the new challenge to the power grid.This project aims at improving the performance of “the first line of defense” of power grid.By means of utilizing the substation-area integrated information and advanced communication technology,it will focus on the study a new architecture of Remote Duplicate Configuration Protection Center(hereinafter referred to as “Intelligent Protection Center”)aiming at improving the high reliability and rapid recovery of substation clusters in the key areas of the power grid.Because intelligent protection center is a new structure and concept proposed for the first time,and one of its purposes is to improve the reliability of station protection in intelligent substation,so its own reliability is particularly important and needs to be studied.The research contents and results are as follows:Firstly,according to the cooperation relationship between Intelligent Protection Center and dual intelligent substation protection under two working modes of hot standby and cold standby,Petri net(PN)model is established respectively,and Hierarchical Petri net Simulator(HiPS)software is used to carry out the action logic modeling of cooperation relationship between Intelligent Protection Center and dual intelligent substation protection.Modeling and dynamic simulation analysis are carried out.On this basis,PN matrix analysis method is used to verify the established PN model.The simulation and verification results show that the established time series PN model can effectively describe the cooperation relationship between intelligent protection center and dual intelligent substation protection,and indirectly prove the reliable cooperation between them.Secondly,the reliability of communication system based on Intelligent Protection Center is studied.In view of the different locations of the Intelligent Protection Center in the hub substation group,there are two kinds of network structures,and the corresponding backbone network needs to be connected by star and ring modes.In order to obtain the reliability index expression of the communication system of the Intelligent Protection Center architecture under two networking structures,it is necessary to establish Markov state space model for each sub-module of the communication system of the Intelligent Protection Center architecture,determine the logical relationship between the failure rate and the repair rate of each sub-module,obtain the reliability index expression of each sub-module,and synthetically obtain the reliability of the communication system of the Intelligent Protection Center architecture.On this basis,Markov state space method and MATLAB software are used to calculate the reliability of the communication system of the whole Intelligent Protection Center architecture.The example analysis shows that the communication system based on Intelligent Protection Center has high reliability under two kinds of networking,which provides a strong support for its popularization and application in hub substation group.Finally,the reliability of the overall architecture between the Intelligent Protection Center and the substation protection of the intelligent substation is studied.Five kinds of operation schemes between Intelligent Protection Center and substation protection of intelligent substation are designed,Markov state transition diagram is established,and the logical relationship between failure rate,repair rate and states of protection system is established.At the same time,the mathematical expression of reliability measurement index is given by combining the rejection probability,malfunction probability of protection system itself and the availability of backbone network of communication system.Markov state space method and MATLAB software are used to calculate the reliability indices of five operation schemes,and the reliability indices before and after the Intelligent Protection Center is put into use are compared and analyzed.The results show that the new structure of Intelligent Protection Center can obviously improve the reliability of the system when the reliability of dual station protection is reduced. |
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