High Voltage Insulation Research Articles

10-kV, 400-A, 10-kHz Solid-State Switch for Lightning Indirect Effect Test

The lightning indirect effect is the effect of magnetic field induced by lightning, and electrical devices frequently exposed to lightning require verification test against this effect. In order to simulate the lightning indirect effect defined in international test standards, a discharge switch to handle high-voltage and high-current pulses and to operate at high repetition rate is required. This article describes a solid-state switch achieving target simulated waveforms with a very simple structure. The two-pack module insulated gate bipolar transistor (IGBT) module is used for high-current discharge and six modules (12 IGBTs) are stacked in series to handle high voltage. Typical considerations for using a series-stacked structure include voltage balance, synchronized operation, and high-voltage insulation. To satisfy this, a special driving circuit using a high-voltage cable and a toroidal core was applied. Based on this, a totem pole structure-based gate driver that can be applied to a two-pack module was proposed, and it not only enables on/off driving control but also includes a function to prevent self-turn with very simple structure. Through PSpice simulation and experiments, it was confirmed that the voltage balance and synchronized switching operation are achieved. Finally, the experiments to generate the simulated lightning indirect effect waveform were conducted and it was verified that the developed solid-state switch can output high voltage (over 10-kV), high-current (over 400-A) pulse, and operates stably under high repetition rate condition (over 10-kHz).

Design of High-Voltage Power Transmission Insulators Based on Ultrasonic Technology

Design of High-Voltage Power Transmission Insulators Based on Ultrasonic Technology

Aging Characteristics of Epoxy Nanocomposites Doped With Silane-Functionalized Alumina Nanoparticles for High-Voltage Insulation Applications

Aging Characteristics of Epoxy Nanocomposites Doped With Silane-Functionalized Alumina Nanoparticles for High-Voltage Insulation Applications

Polypropylene nanocomposites doped with carbon nanohorns for high-voltage power cable insulation applications

Polypropylene nanocomposites doped with carbon nanohorns for high-voltage power cable insulation applications

Controlling electrical stress of polymeric insulators using zinc oxide microvaristor

Non-linear field grading materials (FGMs) based on zinc oxide (ZnO) microvaristors have been proposed to control the electric stress and prevent premature aging and degradation of high-voltage insulators near the end fittings. The current work reports on the effectiveness of using a laboratory fabricated ZnO microvaristor in controlling the electric stress on an 11 kV polymeric outdoor insulator. The proposed design involved applying a microvaristor-based compound sheet of varying dimensions onto the insulator core under the silicone rubber housing. Experimental investigations showed that the proposed FGMs improved the performance of the polymeric insulator by 38.9%.

Partial discharge based recognition of water droplets location in high voltage insulator using convolutional neural network – Bacterial foraging algorithm based optimized machine learning classifier

Measurement and analysis of Partial Discharge (PD) patterns have appeared as an emerging field in assessing insulation failure in High Voltage apparatus. This paper uses a PD signal combined with the deep convolution-optimized learning machine classifier (DC-OLMC) to predict the location of water droplets in 11 kV polymer insulators subjected to alternating currents. There are two major confront when applying the proposed algorithm: i) Contamination is a significant issue in PD signal measurement, which causes a reduction in recognition rate (RR), and ii) with minimal computing time, high-level feature extraction and recognition. Traditional condition monitoring methods of insulators concentrated on extracting fewer priority features from the input patterns. In the current work, to address this problem, an Alexnet with Bacterial Foraging Algorithm (BFO) based optimized kernel parameter classifier and Translation Invariant Wavelet Transform (TIWT) is employed to remove interference from PD signals. The analysis demonstrates that the suggested technique, with an identification rate of 99.17%, is considered a valuable tool for locating water droplets in high-voltage insulators.

Enhanced surface-insulating performance of EP composites by doping plasma-fluorinated ZnO nanofiller

The surface flashover of epoxy resin (EP) composites is a pivotal problem in the field of high-voltage insulation. The regulation of the interface between the filler and matrix is an effective means to suppress flashover. In this work, nano ZnO was fluorinated and grafted using low-temperature plasma technology, and the fluorinated filler was doped into EP to study the DC surface flashover performance of the composite. The results show that plasma fluorination can effectively inhibit the agglomeration by grafting –CF x groups onto the surface of nano-ZnO particles. The fluorine-containing groups at the interface provide higher charge binding traps and enhance the insulation strength at the interface. At the same time, the interface bond cooperation caused by plasma treatment also promoted the accelerating effect of nano ZnO on charge dissipation. The two effects synergistically improve the surface flashover performance of epoxy composites. When the concentration of fluorinated ZnO filler is 20%, the flashover voltage has the highest increase, which is 31.52% higher than that of pure EP. In addition, fluorinated ZnO can effectively reduce the dielectric constant and dielectric loss of epoxy composites. The interface interaction mechanism was further analyzed using molecular dynamics simulation and density functional theory simulation.

Reed switch protection of double-circuit lines without current and voltage transformers

Protection of 6–35 kV double‐circuit lines from the supply side is suggested. It allows saving copper, steel, and high-voltage insulation in amounts unprecedented for relay protections. The protection is based on the control of sequence of actuation of reed switches fastened near the corresponding phases at a safe distance and of the time Δt between their actuation. The effect of all possible errors on Δt is studied and the number of reed switches required to be mounted near the phases of the lines is determined. The peculiarities of selection of Δt and inductions for the protection operation, points of reed switch mounting, sensitivity estimates, and the fields of use of the protection are analyzed. An example of the selection is considered. The protection operation algorithm is formulated and written in the form of switching algebra functions with allowance for the protection operability in the case of reed switch failures. The correct operation of the protection is shown in all actual modes of operation of the lines (including the failure of one of reed switches). A construction for fastening reed switches at a safe distance from the line phases is presented.

Effect of Fluorosilicone Rubber on Mechanical Properties, Dielectric Breakdown Strength and Hydrophobicity of Methyl Vinyl Silicone Rubber.

Silicone rubber (SIR) is used in high-voltage insulators because of its insulation, and excellent hydrophobicity is very important in harsh outdoor environments. To enhance the hydrophobicity and low-temperature resistance of silicone rubber, methyl vinyl silicone rubber and fluorosilicone rubber (FSIR) blend composites with different ratios were prepared. The samples were characterized and analyzed using scanning electron microscopy, tensile testing, dynamic mechanical analysis and static contact angle testing. The results showed that after blending, SIR and FSIR were well compatible. FSIR had higher elastic modulus and reduced the tensile strength to some extent in SIR/FSIR composites. The addition of a small amount of FSIR made its crystallization temperature decrease from -30 to -45 °C, meaning that the low-temperature resistance was significantly improved. The breakdown strength of SIR/FSIR composites can still be maintained at a high level when a small amount of FSIR is added. The contact angle of the composites increased from 108.9 to 115.8° with the increase in FSIR content, indicating the enhanced hydrophobicity. When the samples were immersed in water for 96 h, the hydrophobicity migration phenomenon occurred. The static contact angle of the samples with less FSIR content had a weaker decreasing trend, which illustrated that the hydrophobicity was maintained at a high level.

Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength.

Current thermally conductive and electrically insulating insulation systems are struggling to meet the needs of modern electronics due to increasing heat generation and power densities. Little research has focused on creating insulation systems that excel at both dissipating heat and withstanding high voltages (i.e., have both high thermal conductivity and a high breakdown strength). Herein, a polyelectrolyte-based multilayer nanocomposite is demonstrated to be a thermally conductive high-voltage insulation. Through inclusion of both boehmite and vermiculite clay, the breakdown strength of the nanocomposite was increased by ≈115%. It was also found that this unique nanocomposite has an increase in its breakdown strength, modulus, and hydrophobicity when exposed to elevated temperatures. This readily scalable insulation exhibits a remarkable combination of breakdown strength (250 kV/mm) and thermal conductivity (0.16 W m-1 K-1) for a polyelectrolyte-based nanocomposite. This dual clay insulation is a step toward meeting the needs of the next generation of high-performance insulation systems.

畜禽舍空间相控分裂导线复合除尘杀菌装置设计研究

Livestock scale breeding is the inevitable trend of future livestock and poultry husbandry. Closed breeding requires excellent environment and livestock and poultry housings contain a lot of dust, pathogenic microorganisms and harmful gases, affecting the health of livestock and poultry and breeding personnel. Most of the common sterilization and dust collection devices for livestock and poultry housings on the market are too high energy consumption, and easy to cause secondary pollution. Therefore, an environmental purification device was designed to absorb dust in the air and kill harmful bacteria by using high voltage pulsed electric field. The device was designed using phase control principle and bundled conductor. COMSOL Multiphysics software was used to simulate the layout of single conductor, twin bundled conductor and quad bundled conductor. It was found that when the conductor was designed as twin bundled conductor or quad bundled conductor, the gradient distribution of spatial electric field intensity was more uniform and the downward trend of electric field was slower, which could effectively improve the dust collection and sterilization efficiency of the device. At the same time, a variety of electric field environments can be set up by using phase difference to meet different environmental requirements of livestock and poultry. The compound dust collection and sterilization device with phase-controlled bundled conductor for livestock and poultry housing space includes high voltage pulse generator, bundled conductor, high voltage special timer, insulator and other parts, which can effectively reduce the dust content in the air, the concentration of pathogenic bacteria, harmful gases, etc. after assembly test and can also reduce the humidity in the livestock and poultry housings.

Advanced Diagnostic Approach for High-Voltage Insulators: Analyzing Partial Discharges through Zero-Crossing Rate and Fundamental Frequency Estimation of Acoustic Raw Data

Acoustic inspection is a valuable technique that can detect early stage defects in equipment, thereby facilitating predictive maintenance. In recent times, ultrasonic sensors have made detecting partial discharges through acoustic sensing increasingly feasible. However, interpreting the acoustic signals can pose challenges, as it requires extensive expertise and knowledge of equipment configuration. To address this issue, a technique based on zero-crossing rate and fundamental frequency estimation has been proposed to standardize insulator diagnosis. In an experiment involving a database of 72 raw acoustic signals with frequencies ranging from 0 to 128 kHz, various types of pollution and defects were introduced to a chain of insulators. By employing the proposed technique, the occurrence of partial discharges can be detected and classified according to type, such as corona or surface discharges. This advanced approach to diagnosis simplifies the process while providing valuable insights into the severity of observed phenomena in the field.

Partial Discharge-Originated Deterioration of Insulating Material Investigated by Surface-Resistance and Potential Mapping

The endurance of medium- and high-voltage electrical insulation is a key reliability element in a broad spectrum of applications that cover transmission and distribution levels, the transportation segment, the industrial environment, and power electronics-based energy-conversion systems. The high electric-field stress and high-frequency switching phenomena as well as the impact of environmental conditions lead to the occurrence of partial discharges (PD) and the subsequent deterioration of electrical insulation. Partial discharges usually occur inside solid insulation materials in tiny voids that may either be located adjacent to the electrodes or in the bulk of dielectric material. This effect refers to both AC and DC systems; however, AC voltage is usually much more intensive as compared to DC voltage. This paper describes a novel combined approach based on surface-resistance and potential mapping to reveal the effects of internal processes and the deterioration of insulating material due to the actions of partial discharges. To realize the research objective, the following two-step approach was proposed. Multi-point resistance mapping enables us to identify the spots of discharge channels, manifesting a-few-orders-of-magnitude-lower surface resistance as compared to untreated areas. In addition, surface-potential mapping that was stimulated by corona-charge deposition reflects quasi-equipotential clusters and the related polarity-dependent dynamics of charge decay. A high spatial and temporal resolution allows for the precise mapping and tracing of decay patterns. Experiments were carried out on polyethylene (PE) and Nomex specimens that contained embedded voids. During PD events, the effective discharge areas are identified along with the memory effects that originate from the accumulation of surface charges. Long-term aging processes may drive the formation of channels that are initiated from the deteriorated micro clusters, in turn, penetrating the bulk isolation. The presented methodology and experimental results extend the insight into PD mechanisms and internal surface processes.

Preface

On behalf of the organizing committee, we would like to welcome all participants to the Fourth International Conference on Emerging Electrical Energy, Electronics & Computing Technologies 2022 (ICE4CT 2022) here in Kedah, Malaysia from 28 - 29, December 2022. ICE4CT 2022 is our fourth conference, jointly conducted by Faculty of Electrical Engineering & Technology, Universiti Malaysia Perlis (UNIMAP), Nandha Engineering College, Erode, Tamil Nadu, India and Centre of Excellence for Renewable Energy (CERE), UniMAP. The fourth edition was conducted in hybrid mode. The physical sessions including inaugural ceremony, keynote address and technical paper presentation sessions were conducted on 28, December 2022 and online technical paper presentation sessions and closing ceremony were conducted on 29, December 2022 in Google Meet online meeting platform.ICE4CT 2022 is an important event that brings academics and researchers from around the world to share our professional experiences, expand our professional networks and receive updates on the latest advances in the field of Electrical Engineering & Computer sciences. The keynote speeches are among the events not be missed by all participants. A prominent and vast experienced speaker Prof Dr. Dylan Dah Chuan Lu, University of Technology Sydney, Australia shared knowledge as well as his latest research ideas and findings in his field.Also, ICE4CT 2022 would have not been successful conference without the submissions of technical papers from researchers who have invested their time & energy writing about variety of topics which includes High Voltage Engineering, Insulation Technology, Power Electronics & Energy Efficient Drives, Computer Vision & Image Analysis, Data Mining & Cloud Computing, Wireless Communications, Medical Informatics, Internet of Things (IoT) applications & many more. As such, we would like to thank all the authors for supporting ICE4CT 2022 and wish you a fruitful discussion.Finally, ICE4CT 2022 would not be possible without the dedicated work and efforts of the organizing committee and its cadre of volunteers who worked tirelessly to develop and strengthen every aspect of the conference. We wish to express our gratitude for your hard work and commitment towards making ICE4CT 2022 a grand success.List of Committee is available in this pdf.

The design and test of the electrical insulation break for the EAST Divertor primary heat transfer system

Experimental Advanced Superconducting Tokamak (EAST) is one of the important steady-state divertor Tokamak physical experiment platforms in the world. The main functions of the high-temperature and high-pressure Divertor Primary Heat Transfer System (DIV PHTS) are to provide high-pressure cooling water for the divertor to remove the heat load deposited on the divertor under the plasma operation mode and to provide high-temperature nitrogen gas for the divertor system to achieve vacuum condition during the baking mode. The stability and reliable operation of the DIV PHTS play an important role in the EAST tokamak plasma physics experiment. The high-temperature and high-voltage electrical insulation break are one of the important components of the system. The main function of the Electrical Insulation Break (EIB) is to break the closed circuit of the heat transfer system to avoid eddy current during plasma discharge affecting the magnetic field distribution characteristics of the tokamak. On the other way, it also needs to meet the requirement, there is no leak of the cooling water and nitrogen gas during cooling and baking operation mode. This paper proposes the design of an electrical insulating break (EIB) to meet the design requirements of EAST tokamak at first. Then the electric field analysis is carried out by using a finite element model to evaluate its electrical insulation characteristics. And the sealing structural characteristics are verified by applying the finite element method under two design modes. Finally, the sealing test result under the high-temperature baking and high-pressure cooling modes are presented to validate the design.

친환경 전기자동차 고전압 절연안정성 측정시스템에 관한 연구

친환경 전기자동차 고전압 절연안정성 측정시스템에 관한 연구

Application of a Phase Resolved Partial Discharge Pattern Analysis for Acoustic Emission Method in High Voltage Insulation Systems Diagnostics

An alternative method for analysis of acoustic emission (AE) signals generated by partial discharges (PD), based on a correlation between voltage phase run and AE pulses, so called phase resolved PD pattern (PRPD), is presented in the paper. PRPD pattern is a well-known analysis tool commonly used in such PD diagnostic methods as conventional electrical and UHF ones. Moreover, it yields various signal analysis abilities and allows a direct correlation indication between measurement results achieved using different methods. An original PRPD measurement methodology applied for AE method as well as some exemplary measurement results and further data analysis capabilities are presented in the paper. Also a comparative analysis of PRPD patterns achieved using various measurement methods and different PD source configurations have been investigated. All presented experiments were done under laboratory conditions using PD model sources immersed in the insulation oil. The main purpose of the presented research is to indicate an all-embracing analytical tool that yields an ability to direct comparison (qualitative as well as quantitative) of the AE measurement results with other commonly applied PD measurement methods. The presented results give a solid fundamental for further research work concerning a direct correlation method for AE and other described in the paper diagnostic techniques, mainly in order to continue PD phenomena analysis and assessment in real life high voltage apparatus insulation systems under normal onsite operation conditions.

Glass fiber network reinforced polyethylene terephthalate composites for support insulators

Epoxy resin has long been used as an insulating material in high-voltage apparatus, although its poor recyclability greatly limits its future application. Fiber network reinforced polyethylene terephthalate (PET), as a low-cost and recyclable material, has great potential to substitute epoxy resin as a high-voltage insulation material. The enhanced fiber network combined with the PET matrix form a semi-‘steel-reinforced concrete’ structure, and can collaboratively improve the tensile strength by more than 50% and the dielectric strength by 25.4%. Furthermore, the breakdown path as well as the fiber distribution are clearly rebuilt in 3D coordinates based on a 3D x-ray microscope for the first time. Experimental and computational evidence show that the fiber network lengthens the breakdown path and improves the dielectric strength. This work provides new perspectives for subsequent research on the electrical properties of bone-enhanced dielectric polymer composite.

Case Study: Optimizing Grading Ring Design for High Voltage Polymeric Insulators in Power Transmission Systems for Enhanced Electric Field and Voltage Distribution by Using a Finite Element Method

This research paper aims to investigate the optimal design of grading rings for high-voltage polymeric insulators in an actual power transmission system, with a focus on improving the electrical representation of the insulator strings. One such subsidiary accessory commonly used with porcelain and polymer insulator strings is the grading ring, which is employed to improve the electric field and voltage distribution surrounding the insulator string. The efficiency of insulator strings can be enhanced by grading rings, as they facilitate a more linear potential division along the strings. The design parameters of grading rings significantly influence their performance on insulator strings. In this study, we examine the optimal design of the grading rings of high-voltage polymer insulators, since no uniform design methodology has been developed for high-voltage polymer insulators, and their optimization is currently the subject of many research studies. The electric field on an outdoor polymeric insulator is examined using finite element method (FEM) software and COMSOL Multi-Physics program. A 2D model is utilized to simulate a 220 kV polymeric insulator. The effectiveness of high-voltage polymeric insulators greatly depends on the dimensions and locations of the grading rings. Therefore, the impacts of the radius of the grading ring and that of its tube and the tube’s vertical position are thoroughly investigated, under dry and humid conditions. To achieve this objective, a search algorithm is employed to adjust the dimensions and locations of the grading ring. The optimization approach in this study is based on determining the maximum electric field across the insulator surface, while ensuring that it remains below the corona initiation level.

Investigation and Evaluation of High-Temperature Encapsulation Materials for Power Module Applications

With the advent of ultra-wide bandgap semiconductor materials, such as gallium oxide (Ga2O3) and aluminum nitride (AlN), higher temperature and higher voltage operation of power devices are becoming realizable. However, conventional polymeric and organic encapsulant materials are typically limited to operating temperatures of 200 degrees C and below. In this work, six materials were identified and evaluated as candidates for use as encapsulants for operation and high-voltage insulation at and above 250 degrees C. High-temperature silicone gel was used as a reference material and was compared with five novel encapsulants including an epoxy resin, a hydro-set cement, two low-melting point glass compounds, and a ceramic potting compound. Gas pycnometry was utilized to evaluate the voiding concentration to avoid partial discharge. Each material was then processed onto a direct-bonded-aluminum substrate test coupon to evaluate compatibility with a commonly used metal-ceramic substrate and processability for use in a power module. The insulation capability of each material was evaluated by testing the partial discharge inception voltage (PDIV) across a 1-mm gap etched in the substrate. The dielectric stability was then tested by soaking the materials in air at 250 degrees C for various intervals and observing the degradation of their PDIVs and appearances. The results of each test were compared, and conclusions were drawn about each material’s feasibility for use as a dielectric encapsulation material for a power module operating at temperatures exceeding 200 degrees C.