The Design And Development Of Supervision System For Medium Voltage Frequency Converter

Variable frequency speed regulation technology has many useful characteristics. It can be applied in many scopes, its effect of saving energy is prominent, its automata can be realized easily and further more its speed regulation capability is excellent, so it becomes the most important regulation method for motors. So far internal technology and product of low voltage variable frequency drive is mature, but high voltage variable frequency speed regulation technology is deficient. High voltage variable frequency speed regulation drive's topology is very complex. It contains many parts, such as rectifier, inverter, DC bus and so on. And the device's running states should be changed on-line according to practical requirements. Supervising and maintaining of the device is very difficult. At present, people make lots of effort in designing variable frequency devices and in improving control strategy. However, the function of on-line supervising, recording and analyzing of the running data are oversimplified comparatively, so practical requirements can't be satisfied very well. Therefore, the research and manufacture of the on-line supervising system of the high voltage variable frequency based on the research experience of microcomputer protecting relaying and supervising device which has been used in electric power system drive is very meaningful. It can play an important role in ensuring the variable frequency device's safety, in accumulating its running experience, in analyzing its fault reason and in improving its capability.At the beginning, the paper introduced and analyzed the application of high voltage frequency converter and its supervising system in home and abroad. Then the paper discussed the design principles and function choice of the supervising system according to the circuit topology of high voltage three-level converter and its running characteristic. Also the hardware and software constitution of the supervising system is proposed. Then the paper introduced the supervising system's basic hardware structure, supervising element and the resource of the selected processor.The frequency converter's running states are phantasmagoric and its regulate characteristic is very complex. So in the design process of the supervising system, the on-line observation function is strengthened to observe the converter's run states timely. In addition, supervising system offers remote observation function in to manage the converters together. The function choice and software designing of the local and remote supervising computers are particular introduced.Most of the high voltage variable frequency drive supervising systems used presently just offer the function to observe the run characteristic on-line. They can't record or analyze the device's run states, fault instances. So the function of recording and analyzing was developed in this supervising system. The system can offer powerful analysis software, including stable analysis software and fault analysis software. The analysis software didn't only display the wave of running characteristic, but also compute and analyze the run data. The basic format of data recorded was introduced in detail in this paper. Meanwhile the structure of the analysis software,the function characteristic and the programming method of the software were discussed.The major practical disfigurement of some supervising systems is their weak communication ability. As the communication protocols are different, it's very difficulty to manage the devices together or to communicate with other automation systems. So the communication ability of the supervising system was strengthened. And"IEC60870-5-103"protocol was used to realize communications. In this paper, the characteristic of"103"protocol was analyzed in detail. Meanwhile the method of how to realize communications was described.Finally, static simulation experiments of the supervising system of high voltage converter are described partly. The results of the experiments show that the performance of the supervising system has achieved the design goals and the system can meet the practical demands.