Planar Sensor for Noise Cancellation During Partial Discharge Detection in Open Substation

Abstract

In compliance with next-generation high-voltage substations, ultra-high frequency (UHF) planar sensors are becoming more popular than ever for their online features in partial discharge (PD) diagnostics. However, PD signals mixing with different noises still exists as a major challenge for UHF sensors. Especially in open substations, telecommunication interferences become predominant noise sources to an external UHF sensor placed outside of the equipment chamber. Despite band-stop filters are additionally connected to UHF sensors for de-noising, the inherent noise cancellation mechanism is not yet found in any UHF sensor. With the best of our knowledge and survey, we are the first to introduce here a planar sensor that inherently eliminates telecommunication interferences during PD detection for open substations even without using any post-processing filters. To design our sensor, we have applied techniques of truncated partial ground plane for wideband characteristics and modified radiating patch for enhanced gain performance. A novel intermingled coupling resonator is designed to remove the GSM-900 band from within the sensor bandwidth. We have tested our prototype both for the free-space propagation and PD detection performances. The prototype has a compact physical size of 16×8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and an operational bandwidth within 792-1414 MHz. For a surface discharge source, the prototype successfully detects the PD signals at the earliest stage. Our prototype minimizes the ambient noise-floor to 2.5 mV and improves the signal-to-noise ratio by more than 27.9 dB which is relatively higher than conventional UHF sensors. The proposed sensor also has potentials of classifying PD sources.