Design Of A High Frequency Detection Circuit For PD

Partial discharge (PD) is a major factor causing Gas Insulated Switchger (GIS) insulation degradation. Among the existing PD on-line measuring methods, ulra-high frequency (UHF) method is the most widely used. In addition, because the dynamic range of the conventional UHF sensor is not large enough to extract the PD signals from the noise, a high-frequency detector circuit based on successive detection logarithmic amplify technology has been designed in this paper, and a large dynamic range and small amplifier of PD detection circuit has been realized.The main work has done as follows:(1) The principle of partial discharge, discharge characteristics, and the method of PD detection has been respectively analyzed. The thesis focuses on domestic and foreign reserches of UHF method and the advantages and weaknesses of UHF.(2) Based on the principle of RF detected, the principle and methods of UHF signal detection is given, with emphasis on principles of successive detection logarithmic amplifier.(3) The structure and function of the PD UHF inspection module is introduced. Based on features of PD UHF signal, the large dynamic range of high frequency logarithmic detection amplifier, matching circuits, and the buffered output circuit is designed, and the detailed circuit diagram is given. The detailed circuit diagram has been made in this paper, and the PD UHF detection has been realized.(4) The relationship and consistency of output with input are tested, and the signal bandwidth, dynamic range, sensitivity and output amplitude of the ultra-frequency sensors are respectively tested and analyzed. The experimental results: the frequency bandwidth is 1000MHz, the dynamic range is 73dB, the sensitivity is -70dBm and the output of voltage is 2.60V.