Design Of Three Phase Energy Meter Based On Modbus

The rapid development of the national economy, push the power demand in allprofessions and trades growing as well as power quality requirements, and the smartgrid emerged as the times require. As an important part of the advanced measurementsystem, which is included by the smart grid, the requirements of electric energy meteralso increase. Meet the basic accurate measurement and billing, pay more emphasis oncommunications, networking and user interaction function. However, China’s electricenergy meter, has no uniform standard in communications technology, the coexistenceof various communication technologies leads to the problem of how to use theappropriate network communication technology suitablely. This paper aims to studyan electric energy meter based on Modbus protocol, and gives the networkingsolution.First of all, this paper reviews the development history of the electric energymeter, introduces the background and significance of the topic, and understands thedevelopment status at home and abroad electric energy meter communicationtechnology and the latest developments. Simply contrasts the current centralizedcommunication technology, analyzes the advantages and disadvantages of varioustechnology. Then, makes the implementation process of the protocol and its electricalinterface clear. Show the framework of Modbus network, and establish the intelligentmonitoring system based on Modbus.Describes the knowledge of the Modbus protocol in detail, conduct a research onCRC checksum algorithm of Modbus protocol, give a detailed analysis of theprinciple of the algorithm, and design a sequence of bytes of CRC algorithm based onthe case of large of electric energy parameters data in the process of transmission. Thealgorithm can reduce the error rate effectively.In the hardware design of electric energy meter, this paper adopts a specialelectric energy metering chip and MCU dual-core scheme. Choice the three-pheseenergy metering chip ADE7758, this program can ensure measurement accuracy andshorten the development cycle, reduce costs. Separate the design of the electricenergy meter into the power supply module, electric energy acquisition andmeasurement module, MCU control module and Modbus communication module.Show the reliable circuit principle diagram and give a reasonable selection of the main chip. Similarly, in the process of designing software, the large and complexsoftware system is divided into four modules in modularization, refined the question,and and facilitate the software design. Give the program flow chart of each module,and writes some important modules program code.Finally, we tested the Modbus communication function. The PC test program wasdesigned and get in network with slave. The bit error rate and anti-jamming capabilityare tested in the communication process, and compared with the low-voltage powerline carrier technology. The results show that, the Modbus protocol has a lower biterror rate and better anti-jamming capability, suitable for electric energy metercommunication function.