Data Acquisition System Design Of Active Optical Fiber AC Current Transformer

In the background of global network automation and the rapid development of digitaltechnology, electronic current transformers based on the new technology photoelectricdetection were studied as the focus.This paper first elaborates system structure information of electronic currenttransformers in the IEC60044-8and GB/T20840.7-2007standards, introducing theoperating principle and characteristics of three types of electronic current transformers basedon sensing heads briefly and pointing out that the active fiber current transducer with air-corecoil sensing heads is the most promising new power metering equipment currently.Secondly, the paper determines primary convertor signal detection method based onultra-low power singlechip MSP430F149with the comparative analysis on three methods ofsignal detection of analog modulation, voltage to frequency conversion and analog-to-digitalconversion. According to low voltage signal by high voltage air-core coil, sophisticatedintegrator with amplification function is designed. Whereas sine signal and negativesemi-period waveform are not allowed to enter the ADC of the singlechip due to the integralamplifier, therefore bias circuit is designed, aiming to convert the sine signals into positivevoltage signals that is received by the singlechip. According to secondary converter,demodulation program scheme based on MSP430F1611is presented, converting the signalsfrom DA converter into the sine signals by smoothing and secondary phase shifted circuit.IAR software is used to write and debug for primary singlechip sending procedures andsecondary singlechip receiving procedures.Finally, the accuracy of data capture system of the active fiber current transducer istested by the signal generator and61/2digital multimeter in this paper.