Partial discharge detection and identification at low air pressure in noisy environment

Abstract

Increasing demand for electric power in more electric aircraft requires a higher operating voltage for the power system that leads to higher electric stress on the insulation system. Operating at high altitudes where the electrical strength of air is weakened exposes the insulation system to even higher levels of electrical stress. As such, the probability of partial discharges (PD), which result in insulation degradation and failure, is higher. The presence of switching circuits in the power distribution system of the more electric aircraft is capable of producing high levels of noise. This noise in combination with the background noise and parasitic impedances will cause high amplitude ringing in the measured partial discharge signal waveform. Here, a method based on the combination of the wavelet and energy techniques is employed to detect PD pulses in a noisy environment under the low air pressure condition. To verify the technique, a laboratory setup consisting of two separate PD sources mounted in low air pressure (33 kPa) chamber is developed where sine and square waveforms are used as the applied voltage. The obtained results demonstrate that the proposed approach offers low computational complexity, high performance in PD phase localization, and robustness in a noisy environment.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Simulation of Current Pulses and Sound Waves Resulting from Partial Discharges in a Needle-Plane Geometry in Air

“…Additionally the ionization reaction term S ph (⃗ r), which describes the ionization rate at point ⃗ r by photons produced during the discharge, as described in ( 5) and ( 6) can be modeled using (8) [29]. I(⃗ r ′ ) is the photon emission rate at point ⃗ r ′ , and g(|⃗ r − ⃗ r ′ |) is the photon absorption function at distance |⃗ r − ⃗ r ′ | from the source.…”

“…It can be demonstrated analytically by solving using Green's function and Fourier transform that (8) is the solution to the sum of screened Poisson equations (10). Solving the three screened Poisson equations ( 10) is much less computationally demanding than solving (8) and gives the same solution.…”

“…Once initiated, a PD causes progressive deterioration of the insulation, leading to full dielectric breakdown. Monitoring partial discharges makes it possible to discover flaws in the insulation and quantify the gravity of these flaws before a complete failure; therefore, there is a great interest in detecting the PDs to assess the state of the isolation of a system [5]- [8].…”

“…Various methods have been used to detect PDs by measuring these phenomena, e.g., it is possible to detect the current pulses using coupling capacitors connected to a machine terminal or high frequency current transformers mounted on electric cables. It is also possible to detect the PDs using ultrasound sensors, UHF detectors, by monitoring temperature or by analyzing chemical substances produced by the electric discharges [6], [8]- [11].…”

Parallel diode‐clamped linear converter for withstand test and partial discharge measurement of electric equipment

“…Although modern Pulse Width Modulation (PWM) inverters have significantly reduced harmonic distortion at low frequencies, high frequency harmonic contents are remarkably increased due to the fast commutation of power electronic switches [5][6][7]. As a result, the accurate PD measurements of electric devices are impossible in such a noisy background [8][9][10].…”