High Arcing Research Articles

An enhanced algorithm for detection of HIAF in active distribution networks and real-time analysis

Identifying a downed conductor in distribution is challenging due to the insignificant variations in the current signal. Most of the distribution system faults are identified using overcurrent and earth fault protection. Fault path resistance decides the current magnitude while high resistance path may create timely issues in identifying a fault. Downed conductor and high resistance faults create arc in between the ground and conductor. Due to this the fault at the location is highly nonlinear with reduced magnitude. These faults are known as high impedance arcing fault (HIAF). Such faults can be identified effectively by conducting harmonic analysis of the signals. But in a modern distribution system apart from other renewable sources, the integration of electric vehicle (EV) may create HIAF detection challenges due to the inclusion of inverters and switching harmonics associated with EV. Considering the available advanced architecture of modern microgrid system, an effective solution is proposed in this work to securely detect HIAFs. The method is robust and highly reliable for HIAFs. The system stability and continuity can be unaffected with the help of the proposed method in case of various non-fault or transient/switching conditions. Comparison with other profound techniques is done to show the superiority of the proposed method.

Optimal Threshold-Based High Impedance Arc Fault Detection Approach for Renewable Penetrated Distribution System

Detection of high impedance arcing faults (HIAFs) in an active distribution network is challenging due to limited fault current contribution from power electronic interfaced distributed energy resources. It may also happen that during the switching operation of any system, component like a transformer, capacitor bank, nonlinear load, and lines, the protection function may fail to maintain security. The secure operation of any detection algorithm depends on the proper selection of key parameters and threshold settings. To enhance the HIAF detection process, the residual current is preprocessed using OTET. The cumulative sum of the fault detection index from the energy coefficients of OTET is used to take a suitable decision. Optimal parameters of the basis function in OTET are obtained using particle swarm optimization algorithm with a wide variety of fault and no-fault datasets. Further, the optimal value of a drift parameter is designed using OTET investigations and utilized in the fault detection index calculation. The selection mechanism incorporated in the method increases both dependability and security. It can be used for grid-connected/islanded modes of the system, different switching events, and grounding connections. The method is also reliable for noise and harmonic contaminated signal and unbalanced system.

Simulation study on oil pressure problems caused by internal faults in oil-immersed transformers

When internal faults occur in an oil-immersed transformer, the transformer oil inside the cabinet is subjected to thermal decomposition at high temperatures or arcing and produces a mixture of hydrocarbon gases with a risk of vapor explosion. Three-dimensional models of AC 220 kV, AC 500 kV, and DC ± 800 kV oil-immersed transformers were developed for numerical simulations. For these three transformers, the pressure distribution clouds inside the tank and the pressure variation curves at different positions discharge after the occurrence of a short-circuit arc fault between winding turns and at the connection between the tank body and the bushing. It was found that within 50 ms after the fault, the transformer oil vapor expanded rapidly and created a pressure difference at the oil-gas interface. As the oil vapor pressure continued to increase, the pressure inside the tank rose suddenly and transient pressure peaks of varying degrees (up to 0.65 MPa) appeared successively at different locations inside the tank. When the transformer tank pressure limit was exceeded, the tank cracked or exploded easily under uncontrolled conditions.

Studying Dielectric Losses of Serially Combined Silicone Rubber and Epoxy Resin

High voltage outdoor insulation systems are conventionally ceramics and glass with several advantages, such as proven in the field, excellent dielectric properties, durability, and long life. However, they are heavy, attract vandals and break easily, and they can lose their dielectric properties easily when subjected to high voltage transients, arcing, and surges. To curb this, polymer insulators are used because they have excellent dielectric properties, such as those of ceramics and glass, with the added advantages that they do not break easily and recover their lost dielectric properties after any electrical transients. Therefore, this paper investigates the dielectric properties of polymeric materials – silicone rubber (SR) and epoxy resin (ER). Some SR samples were manufactured in the laboratory, and others were obtained from the industrial manufacturer. All the ER samples were manufactured in the laboratory. The dielectric measurements were performed with the Insulation Diagnostics System. Within the measured frequency ranges, the dielectric losses of SR manufactured industrially differ from the laboratory-manufactured specimens. This is due to filler materials in the industrially manufactured samples. For the case of serially connecting the SR and ER, there was a higher influence of dielectric loss of SR than the ER, with some remarkable dielectric losses at some frequencies.

An Experimental Study of Short-Circuit Current Making Operation of Air Medium-Voltage Load Break Switches

Replacing SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , the most potent greenhouse gas, with an alternative gas is a challenge faced by medium-voltage load break switches (MV-LBS). Air is a possible alternative, but there are some challenges regarding low dielectric strength leading to high arcing time and dissipated energy. Therefore, understanding the switching processes for both interruption and making operations in air MV-LBS is crucial to designing efficient compact switchgear. This work focuses on making operations in air MV-LBS. A synthetic test circuit and a model switch are designed based on the standards to simulate making operations under fault conditions similar to a real test. The test condition is set to achieve high pre-strike arcing time and energy. The results show that the most destructive impact of the making short-circuit current occurs in the first half-cycle of the load current when the pre-strike arc is formed. For an average short-circuit current with a peak of 22 kA and a breakdown voltage of 20 kV, the switch failed to re-open due to the arcing contacts welding after four successive making operations without main contacts and seven successive operations with main contacts. It has been shown that the total arcing contact mass loss occurs mainly during the pre-arcing time.Increasing the closing speed could be a possible solution to minimize the impact of arcing.

Assessment of pantograph-catenary interaction in a railway overlap section via a novel optical-based method

• Pantograph-catenary interactions at an existing overlap span are investigated. • A novel optical-based method is proposed and implemented at the overlap span. • Single- and double-pantograph train passages are obtained and studied. • Dynamic effects rendering high contact forces, contact loss and arcing are studied. • Peak contact force, transition distance and train speed show a strong correlation. Smooth pantograph-catenary contact is essential for regular train operation. However, catenary section overlaps are locations where peak contact forces occur, which significantly affects current collection quality. This work studies pantograph-catenary interaction and transition at an existing overlap span by using a novel optical-based measuring method. Image sequences of eleven single- and two double-pantograph train passages were processed to obtain wire displacement responses. The unsynchronised vibration of two contact wires was found, and the first contact wire exhibits different modal responses. The spatial motion paths of contact wires were obtained to estimate the pantograph-catenary interaction. Dynamic effects rendering high contact forces, contact loss and arcing were investigated. The results show that pantographs with a long transition distance and a high intersection gradient cause a serve impulse with the second contact wire, resulting in contact loss and arcing. Finally, this study successfully estimated the transition distance and found it has a strong positive correlation with peak contact forces and train speeds. The transition distance exhibits an increasing tendency with increasing train speed. The longer transition distance results in a higher peak contact force.

Research on Dielectric Recovery Characteristic After Large Capacity DC Interruption

The vacuum interrupter-based DC circuit breaker is one of the most important equipments in the DC power system. The dielectric recovery (DR) of vacuum interrupter (VI) is essential for breaking reliability, especially on some occasions with ultra-large fault current such as the outlet of generator. To measure the DR of VI under high arcing current, an experiment circuit is designed and the DR under arcing current from 20 kA to 60 kA is presented in this paper. The influence of arcing current, contact separation, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt</i> before current zero and arcing time on the DR is investigated. Particularly, it's found that under a specific arcing current, there exists an optimal arcing time for DR, and it shows a negative correlation with the arcing current.

A New Sequence Current-Based Adaptive Pilot Relaying Scheme for Modern HVAC Transmission Lines

The transmission system structure may sometimes be modified depending upon the power generation and demand at various locations in the power system. Usually, this leads to updates/changes in the relaying installations and makes the overall system to be more expensive. Therefore, it is vital to ensure the reliability of relaying installations with adaptiveness. This paper introduces an improved sequence current-based adaptive pilot relaying scheme. The scheme with its fixed settings can protect the compensated/uncompensated transmission networks with any structures against any type of faults with low impedance faults or high impedance arcing faults. The performance of the proposed scheme has been scrutinized using EMTDC/PSCAD simulation for almost all the adverse cases of faults for different test systems having different structures including a 9-bus WSCC system, IEEE 14-bus system, and TCSC-compensated line. The obtained results indicate that the scheme is robust, accurate, selective, and consistent for all the cases investigated.

A detection method of high impedance arcing fault for distribution network with distributed generation based on CEEMDAN and TEO algorithm

A detection method of high impedance arcing fault for distribution network with distributed generation based on <scp>CEEMDAN</scp> and <scp>TEO</scp> algorithm

An improved protection strategy based on PCC-SVM algorithm for identification of high impedance arcing fault in smart microgrids in the presence of distributed generation

High impedance Arcing faults (HIAFs) are normally caused by ruptured conductors, leaning of a tree with high impedance, and/or the presence of a high impedance object between the conductor and earth. In such cases, protections available in the microgrid may not be capable of detecting the HIAFs. Hence, to increase the safety level and reliability of the microgrid, it is essential to take action for fast and reliable detection of these types of faults. Therefore, the present study introduces an appropriate strategy to detect HIAFs using a pattern recognition approach. To this end, different scenarios are implemented in the training data extraction step considering the measurement units embedded in a 25 kV microgrid in the presence of Distributed Generations (DG) and Renewable Energy Sources (RESs) in the EMTP-RV software environment. Then, after the initial processing, the scenarios are scaled-down and compared using the Pearson Correlation Coefficient (PCC) and Principal Component Analysis (PCA) methods. Next, the processed data is classified using the Support Vector Machine (SVM) method by selecting the most appropriate kernel. Simulation results in EMTP-RV and MATLAB environments demonstrate that the proposed strategy is capable of fast detection of HIAFs in microgrids with a high level of accuracy.

Preemptive Medium-Low Voltage Arc Flash Detection With Geometric Distribution Analysis on Magnetic Field

As power distribution systems become increasingly interconnected and concentrated with distributed energy resources (DER) and high potential equipment, effectively avoiding the medium-low voltage caused safety risk, drawing more attention. Therefore, the accurate, fast, and reliable preemptive arc detection and location method is essential to be developed. However, due to the issues such as low sensitivity, delayed detection, complex structure, and susceptible to interference by other sources, the traditional approaches are not up to the detection and location job, for weak system source and high arcing resistance featured medium-low voltage arc flash. To overcome the limitations, this article explores a novel arc flash preemptive detection and location mechanism. With the application of geometric distribution analysis on magnetic density flux and current density, mathematical modeling incorporated magnetohydrodynamic approach is developed. With a series of actual cases incorporated simulations were performed, the criterion of arc initiation and concisely numerical model on arc fault location estimation is derived, which shows a good ability to catch the transient dynamics of arcing current in the early initiating stage, and also proves the reliability and accuracy on fast detection and location uses. These results offered valuable information for medium-low arc fault mitigation and hazard prevention.

Distortion-Controllable Arc Modeling for High Impedance Arc Fault in the Distribution Network

Accurate modeling of arc is significant for the researches on the high impedance arcing fault (HIAF), which performs variations of nonlinear distortions under different fault conditions. The diversity of the waveform distortions during HIAFs is rarely investigated previously. This paper proposes a black-box HIAF model to simulate the nonlinear distortions of currents with improved controllability and higher accuracy. Firstly, with field HIAFs experimented in a 10 kV distribution network, three major characteristics varying in the distortions of currents are summarized and illustrated, including the offset, extent, and duration. Secondly, a distortion-controllable (DIST-C) HIAF model is proposed based on the heat balance equation after mathematical assumptions and transformations. The three characteristics of distortions can be independently controlled by the proposed model, specifically, by the three parameters with practical meanings. After illustrating the implementation of the model in PSCAD, an automatic parameter determination method is presented by taking advantage of the particle swarm optimization in a Python-PSCAD-MATLAB co-simulation platform. Finally, the controllability and accuracy of the proposed model are verified by comparing it with the existing typical black-box models.

Study on the Dielectric Recovery Strength of Vacuum Interrupter in MVDC Circuit Breaker

The medium-voltage direct current (MVDC) distribution grids have been given significant attention because of their wide applications in the grid integration of the renewable energy sources and in the improvement of the stability and quality of the grid. However, due to the absence of the natural zero current crossings and the high rate of the short-circuit current, the fault current interruption in the MVDC systems is more problematic than that in the ac systems. Several types of interruption schemes have been proposed, and the vacuum interrupter-based dc circuit breaker (DCCB) is a promising solution for the MVDC interruption. Because of its high arcing current, the dielectric strength of the vacuum interrupter after the current crossing point stays low, which makes the dielectric recovery strength a critical factor for the reliability of the interruption. To estimate the reliability of the MVDC interruption, an experimental circuit is designed to measure the dielectric recovery strength of the vacuum interrupter, and the main influence factors are investigated with the experiments conducted under different arcing currents, contacts, $di/{\Delta t}$ before the current zero, and arcing times. The analysis and comparison of the dielectric recovery strength under different conditions are presented. The safe recovery time under different interruption conditions is proposed.

The State-of-the-Art Methods for Digital Detection and Identification of Arcing Current Faults

This paper reviews approaches used to detect and identify arcing currents, including arcing current faults. The reviewed approaches are categorized as the time-domain, frequency-domain, and time–frequency approaches. The time-domain approach extracts shoulders (zero values of the current around zero crossing points), spikes and jumps, abnormal magnitudes (lower or higher than normal), and high rate of change of the current. The frequency-domain approach extracts the high-frequency components, harmonic components, sub-harmonic components, and cross-correlation indicator. The time–frequency approach extracts high-frequency sub-bands that contain non-stationary frequency components, which may have non-stationary phases. The three approaches are implemented to test their accuracy, computational requirements, and sensitivity to system parameters. These tests are performed by processing of currents that are collected for normal and dynamic conditions, conventional faults, and currents with high or low arcing components. Test results provide a performance comparison for the tested approaches.

Analysis of Gaseous By-Products of CF3I and CF3I-CO2 after High Voltage Arcing Using a GCMS.

Increasing demand for an alternative insulation medium to sulphur hexafluoride (SF6) has led to the investigation of new environmentally friendly insulation gases which could be used in high voltage equipment on the electrical power network. One such alternative, which is currently being explored by researchers, is Trifluoroiodomethane (CF3I) which could potentially be used in a gas mixture with carbon dioxide (CO2) as an insulation medium. In this paper an analysis of gaseous by-products detected as a result of high voltage breakdown through pure CF3I and a CF3I-CO2 gas mixture across a sphere-sphere electrode arrangement is given. Gas chromatography and mass spectrometry (GCMS) is used to identify the gaseous by-products produced as a result of high voltage arcing which causes the gas between the electrodes to dissociate. Analysing these gas by-products helps to identify the long-term behaviour of the gas mixture in high voltage equipment.

A Searching Based Method for Locating High Impedance Arcing Fault in Distribution Networks

Locating high impedance fault (HIF) in a distribution network enhances the reliability of the system and improves the quality of the service for the customers. Due to low magnitudes of fault current and nonlinearity of fault impedance it is a very hard task and less considered by the distribution automation system. This paper introduces a novel method for estimating the location of high impedance arcing faults in radial distribution systems. The proposed method searches the feeders of the network at different locations, to find where the estimated parameters of the assumed HIF would result the most accurate estimation of the faulty phase voltage. The fault current and the arc parameters are estimated at each probable location employing an appropriate model to estimate the faulty phase voltage. As the proposed method uses the time domain analysis, it is applicable for nonhomogeneous distribution networks with unbalanced loading as well as symmetrical systems. The results of simulations of IEEE 34-node test feeder with various HIF parameters by EMTP-RV show that the proposed method is well capable of locating high impedance faults despite uncertainty in the load data.

Experimental Study of High Energy Arcing Faults Using Medium Voltage Metalclad Switchgears

Large-scale electric discharges events called high energy arcing faults (HEAF) have been reported in a nonnegligible number at nuclear power stations (NPSs) worldwide. If a HEAF occurs, the pressure and temperature in the electrical equipment rise rapidly, causing an explosive phenomenon with destructive force that results in serious damage to the equipment. In addition, a HEAF may cause a fire, which would have a serious impact on cables and other components in and around the equipment with the potential to disrupt power, instruments, and control in the plant.In order to investigate the HEAF progression and to understand well the phenomena involved, the Regulatory Standard and Research Department in the Secretariat of the Nuclear Regulation Authority conducted a series of experiments (HEAF tests). High-energy electric arcs were generated at the facility simulating the design and operating conditions of the medium-voltage metalclad switchgears (M/Cs) at Unit 1 of the Onagawa NPS where the fire subsequently spread to multiple M/Cs via cable duct due to HEAF.The test data have been obtained for the M/Cs on the threshold values of the arc energy that results in ensuing fires and on the characteristics of high-energy arcs.On the basis of the knowledge obtained by the test results, measures for prevention of ensuing fire and mitigation of explosion are proposed as a new requirement for fire protection regulation of Japanese NPSs. Amendments to the regulatory requirements were issued on August 8, 2017 and enforced on the same day.This paper summarizes the information on the high-energy arc characteristics and arc energies resulting in ensuing fires that was used as the basis of the new requirements and discusses the trend of arc power.

Mitigation of high energy arcing faults in nuclear power plant medium voltage switchgear

Abstract A high energy arcing fault event occurred in the medium-voltage (13.8 kV and 4.16 kV) metalclad switchgears in a nuclear power plant not only affecting switchgear but also connected equipment due to the arc energy. The high energy arcing fault also causes a fire that influences the safety function of the unit. Therefore, from the safety point of view, it is necessary to evaluate the influences of high energy arcing fault events on the safety functions of nuclear power plants. The purpose of this paper is to elaborate the characteristics of high energy arcing faults and propose a high energy arcing fault mitigation scheme for medium voltage networks in nuclear power plants.

Communication—Room Temperature Photoluminescence Characterization of Impact of Electrical Arcing on Silicon

Corona discharge-based non-contact capacitance-voltage (C-V) measurement technique has been used for characterization of dielectrics on Si. For corona discharge generation, high voltage is applied to an electrode above dielectrics/Si sample. High voltage electrical discharge and arcing experiments were performed on Si wafers to investigate potential impact (or side effect) on electronic properties of Si wafers. Room temperature photoluminescence (RTPL) spectra from Si samples were measured before and after high voltage direct current (HVDC) discharge and Piezo ignition arcing experiments. Distinctive discharge and arcing footprints were observed in RTPL area maps suggesting modification of electronic properties.

Calculation Of Pressure Rise And Energy Of Hot Gases Due To High Energy Arcing Faults In The Metal-clad Switchgear

This paper presents the 3-D CFD calculation results of the pressure rise due to the High Energy Arcing Faults (HEAFs) in the metal-clad switchgears. The calculations were performed considering the came-off of the roof panel that was observed in the arc tests. The calculated pressure development approximately agreed with the measured one. Furthermore, the energy of hot gases exhausted from the broken roof panel was calculated to investigate the thermal effect of hot gases.