Development Of Multifunction Meter In Indicating Instrument Calibration

With the constant development and expansion of the power system,the deeper understanding of power grid,more methods and parameters of power gird detection have been found.There are harmonic analysis、binary 60° reactive power value、 ternary 90° reactive power value and some other new electric parameters, beside RMS 、 frequency 、 phase of voltage and current.Futhermore,various kinds of instruments have been derived,like three wire watt-hour meter、three wire 60° reactive power meter.It could contributes to too much devieces and reduce the efficiency of checkout work if it uses different calibration equipments to measure meters. Instrument calibration meter can slove this problem,it support all kinds of instrument fuctional detection,to improve the efficiency of detection.This research named multi-function meter is a part of instrument calibration, with the multi-function tester and PC calibration control system,they constitute the instrument calibration device.This topic adopts double ARM architecture,the system is divided into AC sampling module and DC sampling module to accomplish AC/DC independent sample as well as a convenience for system maintenance and installation.AC sampling module adopts Coretex-M4 microcontroller and 16 bit high precision、fast A/D chip ADS8568 are used to achieve a high precision AC signal sampling. By using the accumulated deviation synchronous sampling method, the basic electrical paramerters and reactive power are calculated under the different formats.Coretex-M3 microcontroller and 24 bit Σ-△ hight precision A/D chip AD7710 are adopted by DC sampling module adopts to accomplish a high precision DC signal sampling. To improve the anti-interference ability of the system and has a higer stability, the photoelectric isolaton and magnetic isolation circuit are used to completely separate the digital and analog signal. Through the Ethernet interface,LWIP protocol and PC software are transplanted for the fast and stable date communication. So it can achieve the automatic detection between muti-function meter and muti-function tester.The theoretical analysis, scheme-designed, hardware circuit-designed and software-designed are elaborated about the design of muti-function mete on this article. Firstly, the purpose and significance of the research and the present situation of domestic and foreign research are put forward. The function and performance index of the multi-function meter are proposed, and various electrical parameters of the algorithm were expounded.After the overall plan, the description of the hardware structure and software realization are introduced.Finally, the problems and solutions of the hardware circuit and sofeware program are mentioned in the debugging process with a detailed record of the experimental data and results. The comprehensive error of the system reached a magnitude of 0.05, it shows that the design of the fuctions and system indexes in the experimental results have been achieved.