Research And Design Of The Control Unit Of Intelligent Circuit Breaker Based On DSP

Under the well-rounded construction of Smart Grid today, low voltage circuit breaker is playing an increasingly prominent role in the power supply and distribution system. In order to meet the requirements of the development of Smart Grid, to adapt to the needs of the market as well as to enhance the competitiveness of products, researching and designing an intelligent circuit breaker with the functions of intelligence, automation, modular and communication have an important application value. In response to these requests, this paper, after the analysis of the its structure which is based on the traditional low-voltage circuit breaker and the combination with the trend of the development at home and abroad, studies and designs the key component of intelligent circuit breaker-the control unit.In the analysis of the design principle of control unit of intelligent circuit breaker, this dissertation presents an overall structure diagram of the system hardware, then describes the functions of each module. Details of the three-sect current protection function principle and algorithm of the control unit are given. According to the different faults occurred in the actual operation of the line, an operation scheme which is different from the traditional three-sect current protection mode is promoted to achieve the intelligent protection function of the control unit. In the calculation of the electrical parameters, the fast Fourier transform (FFT) is adopted to solve the problem that the traditional method cannot accurately detect the harmonic components contained in the signal, at the same time through the Mallat discrete wavelet transform local characteristics of the contained harmonic are analyzed in the simulation.In the aspect of hardware design, the DSP chip TMS320F2812which has strong data processing ability and high operating speed is selected as the micro-processor. On basis of this, a hardware circuit system is designed with a set of measurement, display, protection and communication. For the king-current fault line, an analog tripping circuit with anti-jamming performance is designed for rapid protection of the circuit breaker. To achieve the communication function of the control unit of intelligent circuit breaker, the RTL8019AS Ethernet control chip produced by the REALTEK Company is selected. Traditional TCP/IP protocol is rewritten under the premise of the standard network protocol via the layers interface function call to achieve the Ethernet communication function. In terms of software design, combined with the hardware system, this article gives the overall design scheme of the intelligent circuit breaker control unit, and each functional module subroutine processes are introduced, including the A/D sampling subroutine, FFT subprogram, LCD keyboard processing subroutine, three-sect current protection subprogram, and the Ethernet communication subroutine. Finally by the debugging of hardware and software systems, the test of functional modules are successfully completed, involving the conditioning circuit, analog tripping circuit, Ethernet communication circuit and so on, and the test on the three-sect current protection operating time is accomplished when the design of intelligent circuit breaker control unit is used in low-voltage circuit breaker. The experimental results show that the intelligent circuit breaker control unit designed in this article has basically reached the expected design goals.