Photon Count Technique as a Potential Tool for Insulation Micro-Defect Detection: Principles and Primary Results

Abstract

The requirements for the construction of a new power system inevitably pose significant challenges and changes to the operation and maintenance of the power grid. To ensure the safe and stable operation of ultra-high voltage (UHV) transmission equipment, this work reports on the principles and preliminary results of using electroluminescence (EL)-based photon counting (PC) methods for early detection of micro-defects in GIS/GIL insulation spacer. In this study, the impact of voltage, gas pressure, and gas composition on the photon response of insulation is examined. Furthermore, the corresponding relationship between defect status and photon response characteristics is explored, along with the discussion of the EL mechanism and its evolution induced by defects. The research results demonstrate that PC measurement exhibits high sensitivity to variations in millimeter-scale defect size, position, and morphology at lower electric fields before partial discharge (PD) initiation. With this regard, this paper reveals promising prospects for the early detection of micro-defects in UHV transmission equipment using PC measurement-based methods.

Detection of defect-induced luminescence in epoxy-based insulation materials via phase-resolved photon counting method

“…The results of the UHF sensor in figure 3 confirm the PD incepts at 4 kV (taking the defect-free specimen as the example), releasing energy through photons, ultra-high frequency electromagnetic waves, etc [21]. The insulation specimen exhibits noticeable PD (UHF signals exceeding 100 mV) when the excitation voltage exceeds 4 kV, with samples having larger defects showing lower PD inception voltages (PDIV) [13,18]. Notably, even minuscule PD (<1 PC) generates light intensities more than two orders of magnitude higher than those in the EL process [12].…”

“…Reinforced by gas ionization: As the voltage is further increased (3 kV), the electric field strength within the insulation remains insufficient to induce radiative recombination and ionization within the bulk of the polymer [17]. Nevertheless, the presence of insulating defects significantly enhances the local surface field strength, and the air near defects will be, thus, ionized under the enhanced electric field [18]. Then, high-energy electrons colliding with gas molecules cause them to enter an excited state, leading to electron release through radiative transitions [19].…”

Simulation and Characterization of Micro-Discharge Phenomena Induced by Glitch Micro-Defects on an Insulated Pull Rod Surface

“…The insulated pull rod is a crucial insulating component in gas-insulated, metaleclosed switchgears (GISs) characterized by its slender, elongated structure and frequent involvement in disconnection scenarios [1][2][3][4][5]. In operational conditions, it is subjected to significant mechanical stress and impact vibrations, necessitating superior electrical insulation and mechanical strength [2,[6][7][8][9].…”