Development Of Fast Transfer Switch Based On Hybrid Technology Of Mechanical And Electronic

As airports, military facilities, hospitals, large industrial production lines and other sensitive load are on the improvement of the requirement of the continuity and reliability of power supply, in order to ensure reliable power supply, generally requires two independent power supply of which one is running and the other is standby. Once the running power malfunctions, sensitive load will be switched to standby power. In this process, mechanical transfer switch often causes electrical equipment's halfway stop, which will cause losses, for slow transfer speed. Therefore,we must make new transfer switch with faster transfer speed.Based on the analysis of the current situation of the development of transfer switch in China and abroad, it is expounded in this article that the classification,application profile and switch mode of transfer switch and specific applications at different positions in power supply system. Meanwhile a fast transfer switch is designed based on the composite mechanical and electronic technology. This switch body composed of two units that a mechanical switch circuit and a solid-state switch circuit effectively combines mechanical switch's static characteristics and solid-state switch's rapid action characteristic. Solid-state switch part is the AC switch realized by Single-phase full wave bridge rectifier that is controlled by high power IGBT.Mechanical switch part is a mechanical fast switch that is designed based on electromagnetic launch technology. According to the characteristics and requirements of composite fast transfer switch, a measurement and control system based on PLC is designed to improve the reliability of the switch.In the second chapter, the design requirement of composite fast transfer switch has been presented. Moreover, the overall structure of composite fast transfer switch has been designed, and it's transfer process has been made. In the third chapter, the basic structure and working principle of fast mechanical transfer switch, which is selected as mechanical switch, has been introduced. Moreover, the working principle electromagnetic launch operating mechanism has been analyzed and elaborated, the velocity measurement experiment of fast mechanical transfer switch has been made,the switching time of the mechanical transfer switch is about 17 ms. In the fourth chapter, the design of solid-state switch part has been presented, the basic structure and characteristic of solid-state switch part has been introduced, the model of IGBT has been prescribed as FS200R07N3E4 R. The IGBT driving circuit has been briefly introduced, and the basic requirements of IGBT driver have been summarized. A briefanalysis has been made on the commonly used driving circuit, and the advantages and disadvantages of each circuit have been pointed out. The optocoupler, pulse transformer and optical isolation three isolation methods have been analyzed.According to the specific requirements of composite fast transfer switch, system signal isolation transmission mode has been prescribe as optical isolation. Finally the Beijing luomuyuan company TX-DF102 has been selected as IGBT driver. It's characteristics have been analyzed, and driving parameters have been given. In order to improve the reliability of the work of the driving chip, an independent DC power supply is designed, which is used to supply the IGBT driver board and the photoelectric conversion board. In the fifth chapter, the measurement and control system based on PLC is designed, the measurement and control system's hardware part includes power supply voltage monitoring module, load current monitoring module, storage and driving module, core control module. The working principle and function of power supply voltage monitoring module, load current monitoring module,storage and driving module have been introduced, and the wiring diagram of PLC core control module has been designed. As for the software part, according to the design requirement of composite fast transfer switch, flow-process of control strategy has been made. And control program has been written on the basis of the flow-process of control strategy.Finally the prototype of composite fast transfer switch has been made. And the experiment circuit is built to test the reaction of the system after the main power supply's one phase malfunctions. The test results show that the system works stably and can quickly and accurately judge the fault of the main power supply, and the switching speed of the power supply is significantly improved compared with the mechanical switch. From the main power supply failure to the power supply switching process is over, the time is about 10 ms, the system fully able to meet the requirements of the sensitivity of the load on the power supply.