Diagnostic aspects of partial discharge measurement at very low frequency: a review

Abstract

Electrical insulation of high voltage (HV) power equipment/apparatus plays very important roles in the sound functioning of power systems. Examining the insulation condition through partial discharge (PD) measurements has considerable importance as the presence of PDs in any HV systems stands for a sign of defects and degradations in electrical insulation. Generally, the PD measurements are performed with a supply voltage of normal power frequency (PF-50/60 Hz). As an attractive alternative, the PD measurement with a very low frequency (VLF-1 Hz or lower) applied voltage has emerged as a powerful diagnostic tool. A PD event is a random physical process, it depends mostly on the availability of free electrons that triggers the PD and the presence of space charge usually originated after a discharge. As the discharge characteristics vary with the supply voltage frequency; thus, the existing interpretation knowledge at 50 Hz may or may not be directly applicable to other test frequencies, particularly in the VLF range. Therefore, to provide a general insight, this paper presents various diagnostic aspects of PD measurements, and at the end, various discharge sources (e.g., void, surface, and corona) and their behaviours under varying the test voltage frequencies are discussed in detail.

Partial discharge signal compression reconstruction method based on transfer sparse representation and dual residual ratio threshold

“…This shows that the K‐SVD dictionary has higher coherence with Φ . However, the distribution of μ between the transfer SR dictionary and Φ is less than 4 and concentrated in [1, 3]. The reason is that the transfer SR dictionary is based on the parameter tuning of the intrinsic pulse dictionary.…”

“…eU ) 20:end for 21:F e = (F e (1) , F e (2) , … , F e (t ∕l ) ) Note: 𝜎 is the EMF iteration residual threshold; d is the maximum number of iterations.…”

“…Partial discharge (PD) is an important parameter to detect the operating condition of power equipment [1]. PD sensors are divided into various types according to different detection quantities, such as high-frequency current transducer (HFCT) and ultra-high frequency (UHF) sensors whose detection frequencies are in the order of MHz and GHz, respectively [2,3].…”

Parasitic Capacitive Couplings in Medium Voltage Power Electronic Systems: An Overview

“…In [93] a correlation between gate oxide degradation and the MOSFET intrinsic capacitive couplings are reported, where it is proposed to use the MOSFET change in capacitance as a precursor to the gate oxide degradation, however the mechanisms behind the proposed correlation are unclear. Another phenomenon related to the insulation degradation in PEC systems is the partial discharge phenomenon, which in various studies have been documented to cause long term degradation of dielectric material insulation properties [94]- [96]. Particularly in WBG enabled MV PECs the partial discharge inception voltage will decrease with higher dv/dt posing an increased threat in terms of reliability [97]- [101].…”

PCA-Enhanced Methodology for the Identification of Partial Discharge Locations

“…PD occurs in a variety of locations and insulation mediums in electrical apparatus. PD may be due to the presence of gas bubbles, voids, or impurities in solid insulation, at conductor-dielectric interfaces, liquid insulation and along the surface of insulators [1,2]. Irrespective of the causal mechanism, PD is a precursor to insulation failure.…”