| With the large-scale intermittent distributed energy and electric vehicles connected to the distribution network,the safe and reliable operation of the distribution network is facing new challenges.In order to meet the challenge,the traditional distribution network is gradually transitioning to an active distribution network,and the technologies related to the wide-area monitoring system(WAMS)that are widely used in the transmission network are beginning to be applied to the distribution network.The purpose is to make up for the existing distribution automation system in the distribution network perception and control issues.There are some problems that need to be solved in the development and application of distribution network WAMS,including device research and development,measurement accuracy,communication technology,optimized layout,advanced applications and so on.Aiming at the two problems of device development and communication technology,this paper studies some parts related to the design of phasor data concentrator(PDC)and high-efficiency communication technology in the distribution network,including three aspects: communication protocol fusion expansion,software design,and data compression.The main research contents of this article are as follows:1)By analyzing the communication traffic flow of the active distribution network,the problems faced by the traditional distribution automation system and its protocol,and the application of the PMU of the distribution network,it is clarified that in order to meet the communication needs of the active distribution network,the communication protocol needs to be integrated and expanded.Further comparison and analysis of the GB/T 26865.2-2011 and IEC 60870-5-101/104 protocols,combined with the advantages of the two,proposed an extension method for the synchronous phasor transmission protocol for the active distribution network.The expansion protocol adds new data types,prioritizes data,and adds new communication processes to meet the needs of the PMU extension remote control function of the distribution network,ensuring the preferential transmission of phasor data and reducing network traffic and local storage.The extended protocol was implemented on the simulated PMU,distribution network PDC and simulated master station,and its effectiveness was verified through experiments.2)By analyzing the application requirements of the distribution network PDC,three key indicators that the distribution network PDC should meet are proposed: access capability,time difference tolerance,and data delay.Based on the structured design,a software design method for distribution network PDC is proposed.For different data streams,the software uses data pipeline,management pipeline,and file pipeline processing mechanisms.The algorithm logic of the program considers the completion of key indicators to ensure the reliability and efficiency of communication.3)The related issues of data compression in wireless communication are studied.Through the test of using 4G LTE technology to transmit PMU data,it shows that 4G LTE is difficult to meet the requirements of PMU for the uniform transmission of data in high transmission frequency.In order to reduce communication traffic,a PMU data compression algorithm suitable for wireless communication is proposed.The algorithm performs lossless compression on phasor data and combines multiple frames of data,effectively ensuring the accuracy of phasor data and reducing the pressure of highfrequency communication.4)The distribution network PDC test environment under the laboratory environment is built,and the simulated PMU software and simulated master station software developed are introduced.The basic functions and performance tests of the developed distribution network PDC were carried out,the test results of key indicators were analyzed,and the proposed compression algorithm was also tested.The test results verify that the function and performance of the developed distribution network PDC meet the design requirements,and also verify the effectiveness of the compression algorithm.Finally,the actual application of this type of distribution network PDC in this project is introduced. |
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