Partial Discharge Detection Method Research Articles

A distributed PD detection method for high voltage cables based on high precision clock synchronization

Partial discharge (PD) is a crucial cause of high voltage (HV) cable failures. Detecting and locating PD efficiently and effectively is paramount for HV cable maintenance. However, the attenuation of the PD signal after long-distance propagation makes it challenging to identify. This paper presents a distributed PD detection method that significantly reduces the propagation distance of PD signals before the sensor captures them. The technique uses the time-of-arrival to locate PD, whose localization accuracy is directly linked to the clock synchronization (CS) accuracy. CS between different sensors is achieved through three times interactions of the CS signal. The linear frequency modulation (LFM) signal is selected as the CS signal, which can generate a significant gain after pulse compression. It ensures that the CS signal can be effectively recognized after the attenuation of long-distance propagation. The paper also introduces a signal discrimination method based on the short-time Fourier transform that eliminates the influence of the LFM signal on PD identification. The cableless CS method makes it easier to set up before the onsite test. A prototype was implemented and tested. The CS accuracy was measured within 4 ns in the laboratory. An onsite test was carried out to evaluate the performance of the distributed PD detection system. A defect was found at a joint location, which was also confirmed by an additional ultrasonic PD test.

Comparative Study on Multiple Methods for Partial Discharge Detection of Gap Defect in Medium Voltage Switchgear

Abstract The medium voltage switchgear is a key equipment in the distribution network of the power system, which directly faces users. Once a fault occurs, it will cause huge economic losses and adverse social impacts. Partial discharge measurement is an important means to ensure the safe operation of switchgear. The physical quantities measured by different partial discharge detection methods are different, so the detection effects by different methods for the same defect are also different. This paper takes the common internal air gap defects of solid insulation in switchgear as the research object, and conducts partial discharge detection tests on real switchgear equipment. At the same time, radio frequency method, ultrasonic method, transient earth voltage (TEV) method, and pulse current method are used to detect and analyze the partial discharge generated by the defect. The results show that the radio frequency method, TEV method, and pulse current method have good detection sensitivity for air gap defects, but the ultrasonic method cannot detect this type of defect. Comparing the amplitudes of the three electrical signals, it can be found that the correlation between the TEV method and the pulse current method is relatively high, while the correlation between the radio frequency method and the two is relatively low. As the applied voltage increases, the amplitude of the radio frequency method changes linearly, which can more sensitively reflect the degree of defect change.

Research on Joint Sensing Technology for Vibration and Dielectric Spectrum of Power Equipment in the Context of New Power Systems

Abstract This paper has carried out the test results of SF6 gas decomposition products and the dielectric spectrum detection, proposed method for the identifying equipment defects based on decomposition products, and the partial discharge detection and diagnosis method for the equipment discharge defects. Combining the above two methods, the GIS discharge defects are comprehensively evaluated by decomposition products and partial discharge detection, achieving the type prediction of latent faults in operating switch-gear. In the aspect of vibration signal analysis, this paper conducts the wavelet analysis of the vibration signals and obtains frequency spectrum results under multi-layer wavelet decomposition. In the aspect of dielectric spectrum analysis, a model of three HN function superposition was used to fit the experimental data to verify the validity of the model, and the characteristic parameters such as the DC conductivity were extracted. It was found their dependence on temperature basically conformed to the Arrhenius formula. On this basis, the thermal aging test platform for the epoxy resin samples was established, and an accelerated thermal aging experiment was conducted at the temperature of 115 °C. The dielectric response test system was used to measure dielectric spectra of the samples with different aging times, compare the dielectric spectra at different aging times, and analyze the reasons for the differences.

Partial Discharge Detection Method of Electrical Equipment Based on UHF Method

Partial discharge is an early symptom of insulation defects. In the field application, the detection method can not accurately identify those noise signals mixed in the partial discharge signal, which limits the detection to a certain extent. Based on UHF method, a partial discharge detection method for electrical equipment is designed. When partial discharge occurs, the exchange between charges, the radiation of electromagnetic waves and the consumption of energy will occur at the discharge position, causing the change of electrode potential. For the phase distribution spectrum, the signal characteristics produced by partial discharge are extracted from three aspects: statistical information, time domain information and frequency domain information. During detection, UHF sensor is placed on the basin insulator, and then UHF signal is received. Insulation defects are identified according to various differential discharge patterns formed by the discharge characteristics of different defects. Test results show that the signal spectrum detected by UHF partial discharge roughly matches the typical discharge spectrum, and it is determined that there is partial discharge in this area. This method has high positioning accuracy and meets the detection requirements of electrical equipment.

Optical Partial Discharge Detection and Diagnosis Method Based on PHOG Features

Optical Partial Discharge Detection and Diagnosis Method Based on PHOG Features

Partial discharge detection method for power equipment based on UHF method

Partial discharge detection method for power equipment based on UHF method

Partial Discharge Detection Method for Power Equipment Based on UHF Method

Partial Discharge Detection Method for Power Equipment Based on UHF Method

Distributed Detection and Acoustic Emission Waveform Retrieval of Cable Joint Partial Discharge

Distributed detection and acoustic emission (AE) waveform retrieval of partial discharge (PD) in power cable joints are significant but challenging tasks. In this paper, we proposed a cable joint PD detection method based on optical fiber distributed acoustic sensing (DAS). Ordinary single-mode optical fiber (SMF) was wound on the outer semiconductive layer to obtain sufficient sensitivity. Coherent optical time domain reflection (COTDR) principle was utilized to detect the phase variation and locate the PDs. The AE waveforms were retrieved by Fourier integration and difference operation. The experimental results indicated that the sensing system had the ability of multi-point monitoring. The PD AE waveforms caused by conductor spike and insulation air gap defects were accurately retrieved.

A Thermal Excitation Based Partial Discharge Detection Method for Cable Accessory

Partial discharge (PD) test has been widely used in condition assessment for power cables. However, discharge extinguish phenomenon occurred in PD detection hinders the effective detection of potential defects in cable accessories. For this reason, a novel PD detection method based on thermal excitation is proposed in this paper to eliminate the extinguish phenomenon and to detect the potential defects in earlier stage. First, the physical processes in PD activity and the reasons for discharge extinguishing are introduced. Then, the principle and mechanism of the thermal excitation detection method are described and analyzed respectively, that is excitation by external heating to break the dynamic equilibrium of charge movement within the defect and further stimulate new discharges. And a finite element simulation model is constructed to determine the thermal excitation parameters. Finally, the effectiveness is validated by performing thermal excitation-based PD test on some defective cables. The experimental results show that this method can significantly increase the number of discharges in off-line test, while also stimulating PD of higher amplitudes in on-line monitoring. This method can improve the sensitivity of PD detection for cable accessories and detect potential defects in early stage.

High-Temperature Partial Discharge Characteristics of Power Module Packaging Insulation Under Square Pulse With High Dv/Dt Based on Down-Mixing Method

Partial discharge (PD) in the high voltage packaging insulation under square pulse with a high slew rate (SR or dV/dt) is one of the main causes of the power module failure, especially for wide bandgap (WBG) devices. But PD under fast square pulse at high temperatures is rarely studied and one of the critical reasons is the lack of an effective PD detection method under fast square pulses. In addition, the existing PD standard defines the PD criterion under sinusoidal alternating current (AC) situations, which is not the actual working condition of the power module. To address that, this paper proposes a down-mixing PD detection method and explores the influence of temperature on the PD characteristics of the power module packaging insulation. The results show that the partial discharge inception voltage (PDIV) decreases as the temperature increases. The PDIV under square pulse is always higher than that under AC voltage. The less the SR and the greater the pulse width (PW) of the square pulse, the lower the PDIV. Physical-based models for PDIV estimation concerning SR, PW, and temperature are proposed for industrial reference. Moreover, statistical analysis of PD magnitude, number, and occurrence phase under square pulse indicates that PD number decreases but PD magnitude increases with the increase in temperature. Higher temperature leads to PDs with large magnitudes, which may accelerate the degradation of packaging insulation.

Partial discharge detection on power equipment using a magneto-resistive sensor

Partial discharges (PD) detection is an effective diagnostic method to assess the insulation condition of electrical power equipment in the high-voltage laboratory or field tests. This paper presents a non-contacting PD detection method for power equipment. The method is based on an extra high-sensitivity adapted giant magneto-resistive (xMR) sensor that measures the magnetic field produced by the PD currents. Firstly, this paper describes the sensor’s relevant principle and signal conditioning circuit. Next, the sensor’s typical performance, including the frequency response and time-domain response to calibrator PD pulses, is measured and compared with our previous work. The results indicate that the xMR system’s bandwidth is improved to the MHz range. Finally, PD experiments are carried out and compared with measurements using a commercially available high-frequency current transformer (HFCT), which allows for verification of the coherence of the results concerning the PD pulses and phase-resolved PD (PRPD) patterns. The results show that PD in a cross-linked polyethylene (XLPE) cable or a gas-insulated system (GIS) with artificial discharging defects is successfully measured, demonstrating the sensitivity and performance of the xMR system for PD detection.

Numerical Simulation Research on Partial Discharge of Particle Defects at Epoxy Interface Excited by High-Frequency Sinusoidal Voltage.

In order to improve the effectiveness of partial discharge detection in attached metal particle insulators, this paper proposes a partial discharge detection method for particle defects in insulators under high-frequency sinusoidal voltage excitation. In order to study the development process of partial discharge under high-frequency electrical stress, a two-dimensional plasma simulation model of partial discharge with particle defects at the epoxy interface is established under plate-plate electrode structure, which realizes the dynamic simulation of particulate defect partial discharge. By studying the microscopic mechanism of partial discharge, the spatial and temporal distribution characteristics of microscopic parameters such as electron density, electron temperature, and surface charge density are obtained. Based on this simulation model, this paper further studies the partial discharge characteristics of epoxy interface particle defects at different frequencies, and verifies the accuracy of the model from two aspects of discharge intensity and surface damages through experimental means. The results show that with the increase in the frequency of applied voltage, the amplitude of electron temperature shows an increasing trend. However, the surface charge density gradually decreases with the increase in frequency. These two factors make partial discharge severest when the frequency of the applied voltage is 15 kHz.

Research on Partial Discharge Detection of Switchgear Based on Ultrasonic Signal Characteristic

With the rapid development of power systems, the switchgear, which is widely used, plays an increasingly important role. Partial discharge is one of the main causes of insulation failure of the switchgear, which is a serious threat to personal and equipment safety. In this paper, the partial discharge of the switchgear is detected based on the ultrasonic method. According to the characteristics of ultrasonic waves generated by partial discharge, a partial discharge detection method for the switchgear based on the characteristics of ultrasonic wave signal is designed. The wavelet threshold denoising algorithm is used to denoise the ultrasonic signal and draw the partial discharge phase distribution map by using the characteristics of low amplitude and wide frequency distribution of the interference signal. Finally, the improved support vector machine algorithm is used to identify and diagnose four types of discharge based on 280 groups of experimental data. By adjusting the kernel function and optimizing the support vector machine algorithm, the final recognition accuracy is more than 90%.

Research on Near-Field Propagation Characteristics of Partial Discharge Electromagnetic Wave Signal in Switchgear

In the authors’ previous research, a new method for partial discharge detection in the switchgear based on near-field detection was proposed. The content of this paper is the continuation of the authors’ previous research. In order to realize the reasonable layout of the near-field magnetic field probe for partial discharge detection in the switchgear, this paper simulates and analyzes the influence of the internal structure of the switchgear on the near-field propagation characteristics of the electromagnetic wave signal generated by partial discharge, and determines the installation position of the near-field probe in the switchgear. Firstly, the propagation characteristics of electromagnetic wave signals in the different media of the switchgear are analyzed, and the switchgear model is established. Then, based on the finite difference time domain method, the influence of different devices in the switchgear on the near-field propagation of the partial discharge electromagnetic wave signal is simulated. The simulation results show that the current transformer, insulator, busbar and cabinet all obviously attenuate the amplitude of the near-field electromagnetic wave signals generated by partial discharge, and the insulator causes obvious signal distortion. Finally, it is determined that the near-field probe can be installed on the inner wall or the right wall near the bottom plate of the switchgear.

Perbandingan Sensor TEV Dan Detektor RC Untuk Pengukuran Partial Discharge Pada Peralatan Tegangan Tinggi

Electrical equipment often faces various issues, with insulation problems being a major cause of failure. This article investigates the comparative effectiveness of two Partial Discharge (PD) detection methods: using Transient Earth Voltage (TEV) sensors and Resistor-Capacitor (RC) detectors. The study was conducted on a metal box with a voltage level of 6 kV. Data collected included Background Noise (BGN) and Partial Discharge Inception Voltage (PDIV), processed using Microsoft Excel and OriginPro 9. Results indicate a correlation between higher BGN values on TEV sensors and earlier PDIV occurrence on those sensors. Background noise significantly impacts the PDIV threshold, influencing sensitivity and insulation risk potential. While PDIV provides a threshold guideline, correlation with BGN helps illustrate the background conditions' influence on PD measurement outcomes. The study offers insights into the importance of considering noise in PD measurements and formulates recommendations for practitioners to choose appropriate detection methods based on specific environmental conditions and electrical equipment.

Radiometric Partial Discharge Detection: A Review

One of the most common failures or breakdowns that can occur in high-voltage (HV) equipment is due to partial discharges (PDs). This occurs as a result of inadequate insulation, aging, harsh environmental effects, or manufacturing flaws. PD detection and recognition methods have gained growing attention and have seen great progress in the past decades. Radiometric methods are one of the most investigated detection approaches due to their immunity to electromagnetic interference (EMI) and their capabilities to detect and locate PD activities in different applications such as transformers, cables, etc. Several review articles have been published to classify and categorize these works. Nonetheless, some concepts are missing, and some improvement techniques, such as PD detection at high-frequency (HF) and very high-frequency (VHF), have been overlooked. We present in this paper an exhaustive review study of state-of-the-art PD detection based on radiometric methods at different usable radiofrequency bands (i.e., HF, VHF, and UHF). Accordingly, we propose a new generic categorization approach based on the detected electromagnetic wave component (magnetic or electric fields) and pick-up location, either from free space or ground cable.

Fiber Optic MEMS Ultrasonic Sensor and its Application in Partial Discharge Detection

In this paper, an optical fiber based ultrasonic sensor was designed and applied to the detection and position of partial discharge (PD). The Fabry-Perot interferometer with a micro-electromechanical system (MEMS) diaphragm has been proven to have high sensitivity, with broadband acoustic frequency response up to 500 kHz and wide directivity. In the PD detection experiment, the minimum detectable pressure (MDP) of the fiber optical MEMS sensor is achieving 0.455μPaHz -1/2. In addition, four ultrasonic sensors are arranged around the ultrasonic source to conduct localization experiments. The results show that the system has excellent localization performance in x, y and z directions. The favourable acoustic performance of the MEMS sensor provides a high-sensitivity and high signal-to-noise ratio (SNR) detection method for PD detection.

Partial Discharge Detection Technology for Switchgear Based on Near-Field Detection

In view of the fact that the partial discharge (PD) signal energy is mainly concentrated below hundreds of megahertz, the ultra-high frequency part of the energy is weak, and the interior space of the switchgear is narrow, this paper proposes a new method for PD detection of the switchgear based on near-field detection. Firstly, based on the principle of PD, the field characteristics of the signal in the switchgear are analyzed. After that, the probe is designed with an electric small loop structure. Based on its equivalent circuit, its measurement principle and amplitude frequency characteristics are analyzed. The influence of probe size and material on amplitude frequency characteristics is obtained by using simulation software High Frequency Structure Simulator (HFSS), and the probe parameters suitable for PD detection in the switchgear are determined. Finally, the performance of the probe is measured by network analyzer, and the PD signal is tested on the simulated PD test platform. The results show that the probe works in the frequency band of 10–200 MHz and can receive PD signals containing more energy information. In the operating frequency band, the reflection coefficient of the probe port is very large, and its interference to the signal near field is particularly small. The probe also has good frequency response characteristics, and the fluctuation in the frequency band is less than 5 dB, which can obtain more accurate PD signal characteristics in subsequent processing. In addition, the probe is passive, with dimensions of 166 mm in length, 104 mm in width, and 2 mm in thickness, which is suitable for placing in the switchgear with small internal space. The results of PD receiving test show that the probe can reflect the occurrence of PD remarkably and accurately.

Application of Ultrasonic Testing Method in Particle Detection of GIS Handover Test

Ultrasonic partial discharge detection is a necessary test in GIS handover test, which is very significant to detect the internal defects of GIS. This article introduces in detail how the ultrasonic partial discharge detection method is applied to the GIS handover test through a case in which the internal particles are found through the ultrasonic partial discharge detection method in the GIS handover test. It also fully proves that the ultrasonic partial discharge detection method is very effective for discovering the internal particles of GIS through this case. The experience of this case can provide a very meaningful experience for the subsequent GIS handover, operation and maintenance tests.

Design of Bowtie Antenna With Rounded Edge and Middle-Sliced Modifications for UHF Partial Discharge Sensor

Partial Discharge (PD) detection using ultra-high frequency (UHF) method has been proven as more noise-resistant in GIS condition monitoring, compared to the conventional PD detection methods, where the common noise frequency range such as in the power plants is below UHF frequency range. However, noise in UHF range may occur at certain conditions. Thus, UHF sensor with high sensitivity is necessary to detect PD-induced electromagnetic wave in UHF range. This paper discusses the modified design of a bowtie antenna as UHF sensor and its performance in detecting PD in the air. The modification method is conducted through simulation using antenna design software, resulting in curved-edge and middle sliced bowtie antennas. The designed bowtie antenna has wider bandwidth of above 300 MHz, reflection coefficient lower than -10 dB, and the voltage standing wave ratio (VSWR) less than 2. During initial design, the antenna geometry including gap distance, wing radius, and flare angle are adjusted to obtain the optimum antenna characteristics. The final designed sensor is then fabricated on a printed circuit board (PCB) with FR4-epoxy substrate material and tested using Vector Network Analyzer (VNA). Furthermore, the modified antennas are also tested in the high voltage laboratory to detect PD in needle–plane electrode. The experiment results show that both modified bowtie antennas can successfully detect the PD signal with correct phase patterns, and that the middle-sliced modified bowtie antenna is more sensitive than the rounded edge modified bowtie antenna.