Research On Non-contact UHF Monitoring And Locating Of Partial Discharge In Substations

Substations play voltage conversion, power distribution, load flow adjustment andvoltage regulation roles in power system, linking the various levels of power grid byusing transformers. Apart from transformers, equipments as well as current collectingbus, high voltage switchgear, high voltage bushing, voltage transformers, currenttransformers and other substation equipments. If the fault occurs within substations,causing the relay action, resulting in relevant line removal, resulting in significanteconomic losses and social impacts. So how to protect the safety and reliability of theoperation of substation high voltage electrical equipments, has great significance in thesafe and stable operation of substations and power system. This paper proposed usingUHF antenna sensors to receive radiation signals from substations partial dischargeoccurred by UHF partial discharge to obtain the time difference of signal, calculating thepartial discharge source position, and a non-contact ultra high frequency partial dischargemonitoring and locating system was developed for the relevant laboratory and field tests.Firstly, the ultra high frequency electromagnetic signals excited by partial dischargeoccured in the high voltage electrical equipment was analyzed in this paper, thefeasibility of using non-contact UHF partial discharge monitoring and locating insubstations was analyzed, and high voltage substation equipment items which should bemonitored were analyzed.Secondly, for complex electromagnetic conditions in substation, the principle of thenon-contact UHF partial discharge monitoring and locating in substations was analyzed.UHF partial discharge monitoring and locating within the substation principle and the useof improved wavelet thresholding method in addition to noise was proposed, theaccumulated energy curve to determine the time from signal the beginning of time to getthe time difference was used, and the partial discharge signal locating calculations insubstations was proposed.Finally, a non-contact UHF partial discharge monitoring and locating system wasdeveloped. Some relevant experimental tests of UHF antenna sensors of the system andthe whole system were carried out both in the laboratory and substation fields.