Power Line Carrier Communication System For Distribution Network Automation

As the development of china electric power industry, it requires higher efficiency of distribution network automation system (DAS) due to the stronge demand on the quality and reliability of power supply. Firstly the research status and future trend of distribution automation technology is introduced in this paper. Then a mixed communication system project is given based on the analysis of communication technology characteristic in DAS. Finally the power line carrier communication (PLC) system is putted forward detailedly, meanwhile, hardware and software are accomplished.The carrier chip IT700 assortting with china grid, manufactured by Yitran company in Israel, is adopted to the PLC system, and hardware such as coupling, filtering, controlling and interface circuit is designed to support the IT700. Couplling and decouplling of the high frequency carrier signal is realized by coupling circuit using inductive-coupled, subsequently, the filtering circuit extracts the carrier signal from power line signal with rich noise. To cut down the cost of control system, a 51 microcontroller executing initializing, address configuration, data sending and receiving, etc, is advanced in the controlling circuit. The interface circuit includes serial port and Ethernet, the former realizes the communication between host and IT700, while the later realizes the connection between the 51 and internet. It solves the conversion of PLC and internet.The software consists of host computer and microcontroller platform with similar software procedure, it mainly contains subprogram of system initializing, data sending and receiving, serial port and Ethernet, data-base. System initializing majorly deals with software reset and parameters configuration. Sending and receiving program, which encapsulates and unpacks data, in accordance with the agreed communication protocol, is the most crucial program of the software. In order to store and analysis the uploaded data, the data-base module is designed in the host computer platform.Finally, the module testing and integrated testing of the carrier device in the laboratory have been finished. The result shows that the design of PLC system meets the expected requirement and supplies a stable, reliable communication.