Study And Development Of Software Platform Of Power Quality Monitoring System Based On Modbus Protocol

A variety of power quality related problems have caused much attention of power workers all over the world. How to monitor and improve power quality has become a new hotspot in the research of power system and electric equipment industry. Aiming at the power quality monitoring, the paper developed the software platform of power quality monitoring system and did some research and practice in sharing power quality system data.Firstly, the cause and harm of various power quality related problems are described. The standards, measuring criterion, analytic methods of power quality are studied. Secondly, it summarizes the features of power quality monitoring and introduces the composition of the system. Demands analysis is carried out based on the purposes of the system. A design schema of software platform is proposed. Using the method of modularization, the whole software is divided into five parts. They are serial communication, data processing, database management, user interface and network communication modules. The software platform is developed with Visual C++ 6.0. Each module's realization and dataflow, programs and running results are given. Thirdly, the Modbus as the communication protocol, data transmission and effective control of master computer over the lower machine is realized through the technology of Windows serial communication. In order to enhance running speed of the system, multi-thread is used and object-oriented method is used in programming. In the end, in order to realize data sharing, the paper studies the Power Quality Data Interchange Format (PQDIF), exploits XML technology into PQDIF files and gives models and examples of power quality data interchange.The software platform of power quality monitoring system based on Modbus protocol, which is designed and developed in this paper, can show charts, give results of statistics and analysis and print related reports. The method to share power quality data between different development platforms, monitoring equipment and analytic tools, has supported a way to promote the power quality monitoring system to develop in the networking, informational and standardization direction.