The Design Of The Close-loop Automatic Control System For The Reference Standard Device Of Heavy Direct Current

The main purpose of the closed-loop automatic control system in the reference standard devices for heavy direct current is to increase the system accuracy as much as possible on the basis that the good performance of the devices,including stability and reliability,can be ensured. This will cause the monitoring of the heavy direct current achieve high preciseness and the calibration of the transfer standard devices and working standard devices better.The focus of this article is the research and design of the automatic control system in the reference standard devices for 6000 Amperes heavy direct current.The principle of the metering standard device for heavy direct current and the importance of the feedback follow-up control system has been discussed in the first part of this article. On this basis,the hardware circuit of the feedback follow-up control system including the link of filter,the link of alternating current amplifier,the link of phase-sensitive demodulator,the link of direct current amplifier and the link of power amplifier has been designed.Next,the transfer function of each link has been deducted,thus,the open-loop transfer function of the system has been derived and the BODE frequency characteristic curve of the system has been drawn. Then,we corrected the system using the method of lead phase correction in order to make sure the stability of the system. With the help of the software named MATLAB/SIMULINK,the system simulation model of the feedback follow-up control system has been constructed,and the correctness of hardware circuit of the feedback follow-up control system has been tested and verified by making simulation experiment.Then,the lag phase correction and the integral drift phenomenon have been introduced in detail,using this method,the approximate proportional-integral regulator has been designed,assuring the stability of the original feedback follow-up control system prerequisite conditions , to increase the system accuracy greatly , reach 1.14155×10^-7 through verification of the simulation experiment. Finally,we get the conclusion that the reference standard device for 6000 Amperes heavy direct current can achieve high accuracy and have a good operational performance,this make it have better value for industrial application.