Partial Discharge Characterization Research Articles

Partial Discharge Characterization in a Defect Subjected to HVDC Cable Operating Conditions

Partial Discharge Characterization in a Defect Subjected to HVDC Cable Operating Conditions

Experimental and simulation analysis for insulation deterioration and partial discharge currents in nanocomposites of power cables

Partial discharge (PD) has a well-established relationship with the lifespan of power cables. This paper has been treated the polyvinyl chloride (PVC) with specified nanoparticles for enhancing dielectric degradation and reducing partial discharge current to extending lifespan of power cables. It has been succeeded to creation new polyvinyl chloride nanocomposites that have been synthesized experimentally via using solution-gel (SOL-GEL) technique and have high featured electric and dielectric properties. The validation of nanoparticles penetration inside polyvinyl chloride during synthesis process have been constructed and tested via scanning electron microscope (SEM) images. The partial discharge current mechanisms in polyvinyl chloride nanocomposites have also been simulated in this work by using MATLAB<sup>®</sup> software. This paper has explored the characterization of partial discharge current for variant void patterns (air, water, rubber impurity) in polyvinyl chloride nanocomposites insulations of power cables to clarify the benefit of filling different nanoparticles (Clay, MgO, ZnO, and BaTiO<sub>3</sub>) with varied patterns inside power cables dielectrics. A comparative study has been done for different partial discharges patterns to propose characterization of partial discharges using nanoparticles of appropriate types and concentrations.

Partial Discharge Characterization of Ceramic Power Electronics Circuit Carriers Assisted by Machine Learning

This paper presents an approach for transferring knowledge about partial discharges in polymer insulators to ceramic insulators with the aid of machine learning. It is shown how various machine-learnable features can be generated from partial discharge measurement data and processed in varying artificial neural networks for classification. It is found that polymer- based partial discharges can be classified using this method. In addition, the Long Short-Term Memory based artificial neural network enables partial discharge cause finding and thus fault detection in ceramic power electronics substrates.

Partial Discharge Characterization of HFO(E) Gas Using Ultra-High Frequency (UHF) Antenna for Medium Voltage Switchgear Application

Partial Discharge Characterization of HFO(E) Gas Using Ultra-High Frequency (UHF) Antenna for Medium Voltage Switchgear Application

Partial discharge characterization through innovative continuous monitoring of medium voltage substation

Partial discharge characterization through innovative continuous monitoring of medium voltage substation

Numerical analysis of temperature characterization of air gap discharge in solid insulation under power frequency voltage

Air gap defects in solid insulation of power equipment can cause partial discharge. Temperature, as an important characterization of partial discharge, can be used as a criterion for the deterioration degree of air gap defects to some extent. In this paper, the temperature characterization of air gap discharge is studied. A plasma-kinetics-based dielectric barrier discharge model is constructed. The calculation method of air gap discharge heat source under power frequency voltage is presented. Moreover, the influence of voltage amplitude and gap thickness on temperature is studied. Obtained results indicate that under the power frequency voltage, Joule (Ohmic) heat contributes 90% to the heat source, and O4+ and O2+ and electron e are the main contributors to Joule (Ohmic) heat. O4+ is also the dominant ion in the mixed gas. As the discharge progressed, O4+ almost all clustered near the instantaneous cathode. The O2+ density generally depends on the electron density, but compared with the electron, the spatial distribution of O2+ density is slightly shifted to the instantaneous cathode. The discharge heat source is positively correlated with the air gap thickness and the voltage amplitude. With the increase in air gap thickness, the rising rate of heat sources will also increase. However, when the voltage is 10 kV, the heat source increases first and then decreases with the increase in the air gap thickness. The discharge does not occur when the air gap thickness reaches above 4 mm. This study provides theoretical support for identifying the deterioration degree of air gap defects from the view of temperature.

Characterization of partial discharges from a protrusion in HVDC coaxial geometry

This paper aims at the detection and characterization of partial discharges (PD) in GIS under HVDC constraints in the presence of a protrusion/metallic particle on the high voltage conductor. It is shown that the use of the IEC 60270 standard does not allow for the detection of PDs. For that purpose, a very accurate steady-state current measurement and a high frequency measurement of the current and emitted light associated with the PDs are performed. The results evidence a close correlation between the PD and the steady-state current and light emission. The transition between pulse and pulseless forms of corona discharges is also evidenced.

Fault Detection for Covered Conductors With High-Frequency Voltage Signals: From Local Patterns to Global Features

The detection and characterization of partial discharge (PD) are crucial for the insulation diagnosis of overhead lines with covered conductors. With the release of a large dataset containing thousands of naturally obtained high-frequency voltage signals, data-driven analysis of fault-related PD patterns on an unprecedented scale becomes viable. The high diversity of PD patterns and background noise interferences motivates us to design an innovative pulse shape characterization method based on clustering techniques, which can dynamically identify a set of representative PD-related pulses. Capitalizing on those pulses as referential patterns, we construct insightful features and develop a novel machine learning model with a superior detection performance for early-stage covered conductor faults. The presented model outperforms the winning model in a Kaggle competition and provides the state-of-the-art solution to detect real-time disturbances in the field.

Measurement and Denoising of Partial Discharge Signal in High Voltage Cables using Wavelet Transform

A huge amount of exploration propagated over the past decade investigates the characterization of Partial Discharge (PD) inception in cable ideology. Underground cables are passed down as surrogate for over hauling in congested areas. The intention of this research is to examine the feasibility of exploring insulation defects present in High Voltage (HV) Cable setup by employing PD disclosure under alternating current (AC) Voltage. Study of PD characteristics has a congregate of predictable distinguished contraption to prove the probity and the affirmation of electrical insulation of Power System. In this work, the cable is exposed into the measurement of PD signal under artificially conceived defects. PD signal parameters are mainly depends on the size of void and applied voltage. In general, the measured PD signal is depraved with interferences. To identify the exact characteristics of PD distinctive and its severity, the PD signal is subjected to Wavelet Transform (WT) for denoising. Different types of WT families with various level is used for de-noising. To identify the effectiveness of the WT for de-noising guidelines like Signal to Reconstruction Error Ratio (SRER) and Reduction in Noise Level (RNL) are used.

A Comparison of Inductive Sensors in the Characterization of Partial Discharges and Electrical Noise Using the Chromatic Technique.

Partial discharges (PDs) are one of the most important classes of ageing processes that occur within electrical insulation. PD detection is a standardized technique to qualify the state of the insulation in electric assets such as machines and power cables. Generally, the classical phase-resolved partial discharge (PRPD) patterns are used to perform the identification of the type of PD source when they are related to a specific degradation process and when the electrical noise level is low compared to the magnitudes of the PD signals. However, in practical applications such as measurements carried out in the field or in industrial environments, several PD sources and large noise signals are usually present simultaneously. In this study, three different inductive sensors have been used to evaluate and compare their performance in the detection and separation of multiple PD sources by applying the chromatic technique to each of the measured signals.

Partial discharge characterization of cross-linked polyethylene medium voltage power cable termination defects at very low frequency (0.1 Hz) and power frequency test voltages

Most power cable faults begin as defects in the cable accessories: terminations, joints, and junctions. Poor workmanship is a common cause of the accessory faults [1], [2]. A contributing problem is that power cable accessories are sometimes conveniently assembled manually on site by subcontractors rather than by the cable or accessory manufacturers, thereby increasing the risk on compromising quality.

Characterization of Partial Discharge With Polyimide Film in $\hbox{LN}_{2}$ Considering High Temperature Superconducting Cable Insulation

High temperature superconducting (HTS) cable has now reached the stage where their application in power systems is in the process of being implemented. Liquid Nitrogen (LN 2 ) and polyimide film have been used as a coolant and insulation in HTS cable systems. Partial discharge (PD) events may lead to material degradation and total breakdown. PD testing is an important quality check for the insulation of HTS cable. Thus it is necessary to consider PD for the insulation testing in LN 2 which is generated in void defects of the insulation layers. The PD characterizations of polyimide film in different defects were investigated under 50 Hz AC voltages in LN 2 and at room temperature (298 K). The results show that the number of discharges and the discharge quantity increase with the increasing of the applied voltage and the defect size. The PD inception voltage decreases when the void defect diameter enlarged and it is higher in LN 2 than that at room temperature. The maximum field strength for HTS tape insulation increases with the defect close to the tape boundary and the addition of contaminant relative permittivity. Obtained results at cryogenic temperature provide necessary information for insulation design and pre-shipment inspections of HTS cable system.

Partial discharges characterization in spherical voids using ultra-short x-ray pulses

This work aims to an improved characterization of partial discharges (PDs) in spherical voids. Start electrons are created by an ultra-short (50 ns) X-ray pulse to eliminate the statistical time lag and the individual PDs are detected with an ultra-wideband detection circuit and a photomultiplier tube. The minimum PD inception field strength is determined by triggering at different phase angles of the applied ac voltage. From this, also the gas pressure inside the void can be calculated. The observed PD characteristic (pulse height, charge magnitude, rise-time, and pulse width) are in agreement with the theory of streamer-like discharges. The measurement setup allows the exact determination of the phase angle of each PD related to the ac phase and an improved modeling of the PD activity can be made. Further unknown parameters (residual field strength, charge decay time constant) can be determined from comparison of the measurements to PD modeling.

Phase resolved analysis of partial discharges in liquid nitrogen under AC voltages

Liquid Nitrogen (LN2) has been used as a coolant as well as a part of the insulation system in High Temperature Superconducting power apparatus. In recent decades, there has been scientific research into the pre-breakdown phenomena in this liquid. The focus of previous studies is on streamer behavior and their governing mechanisms. However, research into the characterization of partial discharge patterns in a composite insulation of liquid nitrogen and solid dielectrics has not been widely reported. This paper presents a characterization of partial discharges in LN2 under AC voltages by the means of phase resolved analysis. The results suggest that discharges in a LN2/solid insulation system occur primarily in the first and third quadrant of the applied voltage waveform due to charge storage effects. Partial Discharge (PD) pulses were also observed before the zero crossing of the waveform under higher electric stress. The conditions under which density change streamers cross a LN2 gap and reach the solid insulation barrier are also discussed. Different PD patterns were observed for different solid dielectric barriers indicating the effects of the solid/liquid interface on the behavior of discharges in point-plane composite systems at cryogenic temperature.

Characterization of partial discharge in composite insulation system with PPLPR for HTS cable

High-temperature Superconducting (HTS) cable systems with high power density and low loss are expected to be a solution for improving the power grid. Many researchers have worked on the development of the HTS cable. For insulation testing it is necessary to consider a partial discharge (PD) which is generated in butt gaps of the insulation layers. The electrical insulation system of HTS cables consists of liquid nitrogen (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (l)) and polypropylene laminated paper (PPLP). N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) cooling system is installed in the power system and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) will flow through the cables after their installation in the system. Filling the HTS cable with N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) in order to perform pre-shipment inspection is costly for cable manufacturers. Therefore, they are trying to find a cost effective method for pre-shipment inspections. One alternative is to use atmospheric pressure air or N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (g) instead of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) for pre-shipment inspections. This paper discusses PD characteristics in a butt gap of HTS cables in different environment such as atmospheric pressure air or N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (g) composite insulation. The results are compared with PD characteristics in N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l)/PPLP to find the difference between insulation material in PD characteristics. High temperature superconducting cable, partial discharge, polypropylene laminated paper, insulation system.

Partial discharge characterization of streamers in liquid nitrogen under applied AC voltages

Streamer growth has been examined with the aim to further understand the issues related to using liquid nitrogen as a part of a dielectric system within power apparatus using high temperature superconducting conductors (HTSC). An experiment has been designed to image streamer events in liquid nitrogen for applied electric fields with alternating current using a technique that allows time correlated partial discharge signal and image capture of the density-change streamers. This method employs high speed digital imaging at 5,000 and 30,000 frames per second with stroboscopic backlighting of samples. Samples are point-plane with divergent electric field geometry and consists of liquid nitrogen and a composite solid barrier preventing total field collapse during discharge. Magnitude of apparent charge and phase relationship of partial electrical discharge in liquid nitrogen have been correlated to simultaneously captured images of the resulting density-change streamer. Images of streamers at different points on the applied wave are shown to highlight that different physical mechanisms of propagation occur, phi-q-n plots of partial discharge activity are presented for a range of applied voltages, bulk liquid temperatures and pressures. Analysis of obtained results support the hypothesis that positive filamentary streamer growth is caused by ionization processes occurring in the liquid phase.

Characterization of Partial Discharges in a Gas Insulated System Using an Acoustic Emission Technique

The major cause of failure of GIS is the presence of foreign particles causing partial discharges/corona in the insulation structure. In the present work, partial discharge activity in GIS under AC, DC, and the composite voltage formed by AC and DC voltages, was studied using the acoustic emission technique. It is observed that the magnitude of the acoustic emission (AE) signal produced due to partial discharges under positive DC is high compared to negative DC and AC voltage. Under the composite voltages, it is observed that superimposing AC voltage over positive DC enhances the partial discharge activity, and superimposing the AC voltage over the negative DC voltage could limit the partial discharge activity. The rate of rise and the duration of the AE signal indicates that partial discharge activity under positive DC voltage is severe compared to AC and negative DC voltages. The measured counts and energy content of the AE signal produced due to partial discharges under positive DC is high compared to the negative and AC voltages. It is also realized, based on a partial power analysis, that the maximum energy content of the AE signal lies in the range 125–250 kHz, for the signals generated under AC/DC/composite voltage formed by AC and DC voltage.

Diagnosis and monitoring of high-voltage insulation using computerized analysis of partial discharge measurements

Transmission of electrical power requires various types of apparatus. All the apparatus and transmission-line conductors must be insulated from the high and extra-high voltages arising from the need of transmitting a large quantum of energy. As the need grows, the quality and reliability of the insulator must also grow to handle extra stresses. Hence an attempt is made to evaluate insulation in power apparatus based on the computerized analysis of partial discharge (PD) testing measurements and observations, leading to the identification of PD fault-sources of electrical insulation degradation. The database offers a decision-making aid for product development and supports condition monitoring, assessing the state of insulation. By conducting suitable experiments on two-electrode models, one does partial discharge characterization by considering one PD defect at a time. Using the database extracted from the various PD distributions attained from physical models fabricated, PD sources or defects in simple power apparatus such as surge arrestors, current transformers and artificially created defects such as slot models and rigid terminal connectors are identified successfully and evaluated. Successful recognition rate is achieved with the developed software package even in the presence of two PD sources; say, surface and internal discharges contributing to electrical insulation degradation.

On-Line Digital Computer System for Measurementof Partial Discharges in Insulation Structures

An outline is given of the nature of partial dischargesoccurring in insulation structures, in particular in oil impregnatedconfigurations. It is suggested that conventional discharge measuringsystems are not always able to assess significant parameters becausemuch of the available information is inevitably discarded during thehigh-voltage tests. A mobile computer-based data-acquisition system hasbeen developed for recording and storing, in digital form, the statisticalinformation present. The equipment described is capable of recordingand analyzing the small disturbances produced by partial dischargesunder practical conditions. The computer programs enable the time ofoccurrence and the magnitude and polarity of the pulses to be recorded;in addition, digital transient-event recorders can be programmed toaccept slow partial discharge shapes or ultrasonic transducer outputsfor storage in the computer system. A wide range of playback programsare described and possible methods of presenting the results are discussedusing examples obtained from a 50-kV high-voltage test arrangement.The problems of hardware development are outlined, including thoseof interfacing and operation in hostile environments. The economics ofsuch a system are mentioned and methods of effecting cost reductionsare suggested.Finally, this paper suggests that if on-line characterization of partialdischarges becomes possible then the results of discharge measurementswill have greater significance than at present, especially in those borderlinecases where interpretation of results is difficult.