Ubiquitous UHF monitoring system for partial discharge detection and trending

Ubiquitous partial discharge (PD) detection in electrical power assets is needed to provide predictive maintenance for insulators in smart grid critical assets. A low cost solution is discussed that uses simple electronics and algorithms to interpret ultra-high frequency (UHF) signals as a combination of external noise, asymmetric partial discharge (such as corona and other surface discharges), and symmetric partial discharge. The paper describes a device using three UHF frequency bands and a logarithmic detector to provide baseband signal to a digital signal processor (DSP). The DSP employs discrete Fourier transform (DFT) methods to obtain a rapid and succinct quantification of the contribution to the UHF signal from noise sources vs. surface and internal discharge activity. While UHF methods cannot be calibrated in the sense of IEC60270, an apparatus and method for normalizing the response of in situ systems is discussed.