Research On Network Message Playback System Based On Relay Protection Tester

Smart substation is one of the core platforms to realize energy conversion and control in the construction of strong smart power grid,it is mainly composed of substation layer,process layer and bay layer,network packets are used to realize data sharing between each layer.Secondary intelligent equipment has function of monitoring,controlling and measuring sunstation,its operation condition and performance play a vital role in the safe and reliable operation of substation.Therefore,the relay protection tester,as a test tool for secondary equipment,should be able to simulate the normal and fault conditions of substation's actual operation.Most of the secondary devices in the station are network acquisition and network trip,that is,input SMV and GOOSE messages and output GOOSE messages.With the development of outdoor installation protection equipment,the device of direct acquisition and direct trip is also used in smart substations,in order to adapt to changes,the relay protection tester should have both digital output and analog output functions.In order to simulate the actual operation of the substation,the relay protection tester should have the functions of network packet collection,analysis and playback,also should have fault waveform analysis and playback function.The main research content of this paper is the network message playback system based on digital and analog mixed relay protection tester.The playback system uses modularization,involving the source of playback data,processing and presentation of intermediate data,playback data generation and playback message output.The above functions correspond to input module,analysis module,playback module and output module respectively,according to different data sources,The analysis module is divided into message analysis module and recording analysis module.The input module is to capture the network message frames,or parse offline pcap or pcapng message files to get message frames,or parse comtrade files to get sampling point data,then distribute them.The message analysis module receives the message frames distributed by the input module,according to network type and control block,analyzes and classifies them,displays the results in various ways.The recording analysis module receives the sampling point data distributed by the input module,performs further interpolation statistics,displays the analysis results,and draws the sampling waveform.The playback module is select and edit the message frames of the message analysis module,or edit and select the sampling channels data of the recording analysis module and configure the control block information,set the output outlet,and generate the shared memory block.Theoutput module reads message frames in memory or packs sampling point data into message frames according to configuration information,fills the sampcnt,resets the output time,carries message frames to the hardware outlet,and sends them out at the specified time.In this study,the data structure is divided into three layers: the interface layer,the intermediate service layer and the hardware layer,so as to facilitate the extension of future functions.The hardware core of relay protection tester uses multi-core and heterogeneous mode,and the performance of communication and data interaction between processors is better.The software is developed using Qt framework and can be used across platforms.