The System Of Phase Selection Based On Signal Processing

Which is to solve for phase-selection is how to eliminate the non-periodic component in detection circuit,that is how to control the actuator to closing with Specified time and circuit does not produce non-periodic component,this can prevent Breaker'error, product testing error and threat to human life and property. Therefore, the technology of selection phase AC plays a vital role in closing not only Breaker'detection but also other AC circuits.The paper introduces a project which is based on single-chip comput and signal processing based on the Technology of Phase Selection of AC Apparatus in the experiment of testing instantaneous characteristics for moulded case circuit break and considering the existing problem of slower sampling rate and phase selection ways etc.The phase selection making device is designed with a single-chip computer C8051F060 as its core. Also the paper designs the hardware and the software of the apparatus. The designs of hardware include the devise of executant and controller, the processing of voltage signal in phase,also the design of minimum system of the one-chip computer.Because of the limitation of the SSR, the actuator chooses the SCR which responses very quickly. The single-chip computer controls the turn-on and turn-off of SCR through the optical coupler. At the same time, the electrical source voltage signal is turned into quadrate waveform which brings the interruption to the single-chip computer and detects its zero. When receiving closing command, in order to prevent errors caused by frequency fluctuations MCU measure real-time frequency first and calculated the delay time according to power factor angle,and then capture the voltage zero-phase points, closing by delay.The communication interface circuits of single-chip computer is designed. In the software design, the programmes of the single-chip computer getting the closing making angle,serial port interrupt serving and exterior interrupt serving,accomplishing pahse selection making which uses the technology of computer timer interruption are written.Power factor angle is Obtained by digital signal processing technology,that is FFT.Communication programme of PC is written by Labview.This device has been used on breaker's instantaneous characteristic test equipment, eliminating the transient current in the experiment effectly. The project enhances the precision in calculating the phase of the signal, and improves the precision of the phase selection.