The Development Of Supervision System For Medium Voltage Frequency Converter

With the development of thermal power plants,the problem of waste of resource is getting more and more important.As the resource such as water,wind and coal should meet the demand of load,so the pumps and fans should be controlled according to the load. Most of pumps and fans are drived by single-speed motors,and controlled by valves,which brings much waste.However,as the development of high voltage frequency converter,big power motors such as pumps and fans can be frequency and speed regulated,also can reduce resource waste effectively. But the domestic research of high voltage frequency converters remains the start-stage of application,and the technology is unmature with no sufficient experience,furthermore,the converters'construct is complicated and faults are easily caused,also online modify should be made according to converter's state,so the monitor and manage system should be highly abled to meet all these demands. While the attention is paid on the design of main circuit with little attention paid on the supervision system,so the designed supervision systems for converters are lowly abled with low efficiency management.Thus,it is urgent and important to develop a high-efficiency supervision system.At first,the paper introduced the application situation of high voltage frequency converter in power system,and analyzed the research orientation of development. Based on the design experiment of the 6kV/1000kW high voltage frequency converter,preliminary scheme design was presented. Then the design rule and the function characteristics of preliminary scheme design were discussed,furthermore,the hardware design of the primary system and secondary layer were presented.As an important role of the whole system,supervision system played as the connection between the user and the system,it should monitor the whole converter and provide the function of communication.Based on the analysis of supervision system's application demands,preliminary scheme design for the supervision system was presented including the characteristic of hardware and the function set and the basic frame.The communication module and monitor module are the main part of the research.Monitor module meets the monitor function of the whole system which is treeview- managed,the paper introduced the realization technology of this manage mode.Communication module provided the function of communication.Based on the protocol of IEC 60870-5-103,the paper presented a new set of protocol which meets the demands of medium voltage frequency converter application,its main rules and analysis were discussed in detail.Furthermore , the serial port communication and ethernet communication realization were also presented.At last,after the software was programmed,static simulation experiments were made to test the whole supervision system,the experience tests and results were demontstrated. And the tests proved that the software meets the basic design standard.