Research And Design Of The Node Of The Intelligent Distribution Network Communication System

Nowadays, China starts to build smart distribution network in an all-round way. The intelligent communication transmission unit plays a more and more crucial role in its application in distribution-grid system. In order to satisfy the development of smart distribution network, demand of the market and the communication requirement of each automatic equipment room in smart distribution network, the design of a communication transmission unit has great practical value. This thesis proposes the key device of communication unit:intelligent transmission unit, incorporating its developing trends and characteristics at both home and abroad.In the thesis, the construction state of smart distribution network in Yangzhou is analyzed, and the network structure diagram is put forward. Communication protocol IEC60870-104 and simulation software OPNET Modeler is also introduced in this thesis. The features of EPON (Ethernet Passive Optical Network) and OPNET Modeler are combined to establish the simulation network node and model based on one line of Yangzhou’s smart distribution network. Simulation analysis proves the feasibility and validity of smart distribution network. It is proven that the vital role intelligent transmission unit plays in transmitting data in communication network.STM32F107VCT6 is selected in the thesis as the hardware of intelligent transmission unit. It has high performance but low cost and power consumption. Meanwhile, it has ARM Cortex-M core for embedded application. Owing to it, the author designs a hardware circuit system with various functions, such as voltage and current collection, frequency measurement, in-out of digital quantity and communication. However, the focus of the thesis is on the communication aspect so it includes RS232, RS485 and Ethernet in communication module. For better performance of Ethernet, DM916AEP from DAVICOM is utilized as Ethernet controller because it can make IEC60870-104 protocol transmit more reliably in Ethernet.As for designing the software of intelligent transmission unit, the thesis refers to the features of IEC60870-104 protocol in Ethernet and proposes the overall plan. It also introduces subroutines of every module, mainly including A/D sampling, frequency capturing, FFT, in-out of digital quantity and Ethernet communication.In the end, the main functions of IEC60870-5-104 protocol in Ethernet are achieved after circuit debugging, A/D sampling, frequency capturing and Ethernet communication. The result indicates that the intelligent transmission unit the thesis designs reaches the expected design objective.