Optimum Design Of Secondary System For 500kV Smart Substation

Smart substation is the source of power supply data acquisition and command execution unit,but also to achieve the main manifestation of smart grid automation features.The smartsubstation can realize the digital interface with the primary device by adding the process layer network.The reliability of the process layer network transmission will directly affect the safe operation of the smartsubstation,and should focus on how to improve the reliability of the 500 kV process layer network transmission.Smart substation due to increase the middle of the process layer network to achieve the link,bringing relay protection to extend the whole group of action time.The current version of the 2011 version of 2015,the National Grid Corporation "general design" 500 kV voltage level process layer sampling methods are not both take care of the rapid protection of the relay and the whole station sampling data sharing problem,500 kV smart substation 220 kV side due to the use of digital sampling,electric protection of the whole group of action time extension problem,should be in the two versions of "general design" based on the design optimization.The main work of this paper is as follows:(1)By analyzing the function and flow of each layer network of smart station automation system,the topological structure of layer and process layer in each layer is determined.The advantages and disadvantages of five kinds of sampling and tripping network in process layer are analyzed emphatically.Stage 220 kV and above voltage level substation process layer network using direct-current relay direct jump,SV / GOOSE network alone or a total network transmission program.(2)Based on the analysis of the shortcomings of reliability of 500 kV process layer network configuration scheme,this paper puts forward the principle of network reliability based on switch N-1 and N-2 failure mode,and improves the reliability of 500 kV process layer network The optimized design scheme is: According to the string configuration switch,SV,GOOSE common network,double protection of each set of independent dual-network,dual protection,respectively,access to their own dual-network.(3)By studying the influence of the digital sampling method of 500 kV smartsubstation on the whole operation time of the relay protection,it is concluded that the digital sampling has the influence on the quickness of the line protection.The optimal design scheme of the 500 kV process layer is proposed as 500 kV line protection using the cable analog direct sampling,500 kV component protection using SV point to point direct sampling,500 kV monitoring and control devices,fault recording and so on using SV network mining.(4)Through the research on the longitudinal integration design of 220 kV secondary function localization,the author put forward that using the localized multi-function protection device to solve the problem of extending the whole set of operation time of 220 kV digital relay protection in 500 kV smart substation meets the new generation secondary substation smart substation localization,miniaturization,integration,modular construction requirements.By using the above optimization design scheme,the reliability of 500 kV process layer network transmission is improved,and the problem of prolonging the operation time of 500 kV line protection and 220 kV line(busbar)protection after digital sampling of the merging unit is realized,which embodies the smart substation data sharing the advantages,while saving a lot of cable,fiber optic cable,reducing the workload of the site,reducing the project cost,in line with a new generation of smart substation construction requirements.