The Study On Corona Monitoring System Of High Voltage Transmission Line Under Powerful Electromagnetic Interference

With the increasing national demand for electricity, the high voltage level of theUltra High Voltage transmission lines are elevated accordingly, so the probability ofcorona discharge is also increased. Corona discharge will generate various hazards toequipment and transmission lines and bring great loss. Due to the complex electro-magnetic interference applied to high voltage line, it is indispensable to detect weakcorona discharge.In order to receive the high-voltage transmission line corona, we put forward aproposal which contains integrated spiral antenna receiver, differential amplifiercircuit common mode interference suppression and all-phase filtering detection basedon corona interference analysis. At first, in order to make the corona signal reachhelical antenna with same phase, it needs to arrange helical antenna reasonably. Thenit need to control coaxial cable extension cord of spiral antenna to achieve250MHzcomponent phase-inverted. Then, after amplification and filtering we would obtain10groups of differential signal, each of two differential signals which pass differentialamplification to suppress the common-mode component of the noise and enhancecorona signal in the signal. Finally, it need to use high-speed data acquisition card togather signal, do fourier transform and the short-time fourier transform analysis, anddesign appropriate all-phase filters to detect corona component in signal. Experimentsshow that: three theoretical assumption of the thesis is correct, the detection schemecan not only detect the indoor corona, but also be able to detect outdoor corona whichcontain strong electromagnetic interference and close interference, it has broadapplication prospects.