Research On Synchronous Control System Of 126kV Permanent Magnet Vacuum Breaker

Synchronous control technology can not only effectively reduce overvoltage and inrush current in the process of circuit breaker closing, but also can effectively restrain restrike overvoltage in the process of circuit breaker opening, so as to improve power supply reliability. The characteristic of small discreteness of opening and closing time for permanent magnet vacuum circuit breaker (PMVCB) enables synchronous control technology to be reality. The thesis carries out research and development work for synchronous control and parts of monitoring functions of PMVCB and designs hardware and software of Synchronous control system which has been verified with experiment. The thesis is helpful to improve the level of synchronous control technology of PMVCB, and promotes its engineering application.Firstly, the thesis introduces structure and working principle of two kinds of common PMVCBs and states the research status of PMVCB and synchronous control technology. The best close phase angles of loads of capacitor, no-load transformer, no-load line in synchronous closing are obtained by mathematical analysis and Matlab simulations. The influence of preliminary breakdown, capacitor voltage, operating temperature and so on on the synchronous control is qualitatively discussed. At the same time the thesis introduces three kinds of calculation methods for the parameters of power grid and the Fast Fourier Transform (FFT) algorithm principle is analyzed mainly. Also the thesis compares the advantages and disadvantages among root mean square algorithm, sine relationship algorithm and FFT algorithm.Secondly, in view of the capacitor charging voltage requirements, the thesis designs relevant charging circuit and the parameters of the various components and verifies the charging circuit using Saber software. In addition, the thesis also designs:DSP power circuit, driving circuit, power grid signal zero crossing detection circuit, communication circuit, capacitor voltage and coil current sampling circuit, power grid voltage and current sampling circuit and so on. On the basis of the hardware circuit, the thesis writes upper and lower computer software programs. The lower computer software program mainly includes the main program, data acquisition and processing program, communication program, which are introduced by drawing flow charts. The upper computer software program mainly includes serial port parameters setting module, opening and closing operation module and information display module, realizing the remote control and information acquisition of the PMVCB.Finally, an experimental platform for synchronous control is set up. Synchronous opening and closing experiments are performed on 126kV monostable PMVCB with designed synchronous control system. The experimental results show that the error between the opening and closing time of PMVCB and the reference signal of power grid keeps within 1ms, and meet the design requirements.