Research On Communication Of Power Quality Monitoring System Based On CAN Bus

Power quality has been paid more attention because of the wide use of non-linear load and increased requirements from electrical and electronic devices. It is not only a problem about how devices run safely, reliably and economically, but also about the standardization of power supply market. In order to provide basements for improving power quality, coordinating suppliers and users and standardizing power supply market, power quality should be monitored and analyzed.Therefore, it is a import to research and develop a new power quality monitoring system with multi-functions of measurement, analysis, control and communication for running the electric power system safely, economically and reliably. The communication is one of the core technologies of the monitoring system and its performance directly affects the performance of the entire system. In this paper, functions of the power quality monitoring system are studied, a distributed system based on CAN bus is designed and its communication of real-time is analyzed.First of all, communication and functions of a power quality motoring system was analyzed. through comparisons, CAN bus was chosen to be the communication net due to its low cost, high efficiency and high reliability. A PCI CAN communication card was designed by using the PCI interface chip PCI9052 of PLX. The card driver was developed by WinDriver to realize data communication between computer and power quality analyzer.The application layer protocol of CAN bus was established, including format of data frame, identifier, strategy of data transferring and data coding, according to the protocol Data acquisition program was created and human interface was constructed by RSView32. An EXCEL DDE server was designed to link data acquisition module with human interface for real-time displaying power quality parameters, analyzing the trends and recording waves and events.According to a message transmission delay model, CAN bus transmission neat delay and MAC access mechanism were analyzed. Hence, A CAN real-time accessing strategy was raised based on dynamic time division multiplexing and a math model of MAC was given. This strategy had been applied in this system. At...