Electrical insulation faults produce partial discharges (PD), which can be analysed to identify specific types of defects. PD clustering is a widely used method to identify PD sources, although its success depends largely on the feature maps used. In this paper, three widely used feature maps, or separation maps, are compared: chromatic, energy wavelet with principal component analysis (EW-PCA), and

This article deals with the methods of finding partial discharge (PD) location in power transformers using ultra high frequency (UHF) measurements. The UHF technique utilises two methods to find the PD location, that is, the shortest path method and hyperbolic method. The shortest path method works based on the comparison of the measured data and the ones in the database. In the hyperbolic method,

Nanocomposites are pivotal for enhancing epoxy resin performance, but traditional inorganic nanofillers' poor compatibility and nonrecyclability pose environmental concerns. This study utilises recyclable organic cellulose nanocrystals (CNC) to explore their modification impact on epoxy composite properties. Through infrared spectroscopy and X-ray photoelectron spectroscopy (XPS), the degree of modification

This study investigates vibration changes due to transformer core deterioration by monitoring core vibration, compression force and shell wall vibrations simultaneously. The transformer core operates in a compound environment of mechanical vibration and thermal ageing for extended periods, and the correlation mechanism between core structural deterioration and shell vibration changes remains unclear

To address the lack of voltage ratio standards for accuracy testing of low-frequency voltage transformers, it is necessary to develop a 3 kV low-frequency induction voltage divider. Firstly, based on the analysis of the error sources of the induction voltage divider, a method was proposed to calculate the excitation impedance of the induction voltage divider using complex magnetic permeability. A measurement

The corrosion problems of high-voltage power transmission conductors typically occur in environments with electric fields. However, current research mainly focuses on atmospheric corrosion of metals with limited attention to the combined effects of electric fields and atmospheric conditions on metal corrosion. This study established a corrosion prediction model that considers the effects of electric

Resin impregnated paper (RIP) converter transformer valve-side bushings are the key equipment in converter stations. Local overheating of the RIP core not only reduces the transmission efficiency but also causes insulation failure of converter transformers. In this paper, a new heat dissipation structure is proposed to improve the temperature distribution homogeneity of the bushing using two-phase

Perfluoroisobutyronitrile (C4F7N) is recognised as the next-generation dielectric medium for eco-friendly gas-insulated equipment (GIE). However, there is gas metal incompatibility in strong electromagnetic environments and environmentally friendly insulating gas atmospheres that endangers the operational safety and service life of GIE. Here, a solvent-induced grain boundary reconstruction method was

With increasing electricity demand and large-scale stochastic charging of electric vehicles (EVs), distribution networks face inevitable shortage of transfer capability, bringing new challenges to distribution network planning (DNP). Dynamic thermal rating (DTR), which evaluates the equipment rating based on actual meteorological conditions and equipment thermal state, can enhance the equipment transfer

Digital twin is considered the key technique for real-time monitoring and life-cycle management of electric equipment. To construct the digital twin model of electric equipment, a multi-parameter electromagnetic analysis is needed to generate a large amount of high fidelity data under various working condition. However, repeated solving such multi-parameter electromagnetic problems based on full order

In this study, the functional gradient materials (FGMs) were the first attempt to homogenise the electric field distribution in the cable accessory, where zinc oxide particles (ZnOk) were filled into ethylene propylene diene monomer with the compositionally gradient distribution using laminating and hot-pressing methods. The constructed FGMs with significantly improved non-linear conductivity can avoid

Fast mechanical switches (FMSs) are critical components of DC circuit breakers (DCCBs), which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario, while ensuring a long service life. The breaking mechanism significantly affects the current interruption capability of DCCBs. The operation of the repulsion mechanism, along with the morphology of

Aerospace dielectric components on spacecrafts are frequently exposed to surface charging. Here the dynamic charging behaviours of advanced aerospace dielectrics under electron beam irradiation are investigated. Combined measurement of dielectric secondary emission yield (SEY) and trap distribution provides input parameters of a drift-diffusion transport model reproducing the beam-irradiated dielectric

In recent years, the issue of defects in the buffer layers of high-voltage cables has garnered significant attention due to their widespread occurrence and the substantial potential damages they pose. Although progress has been made in understanding the mechanisms behind these defects and in developing detection methods, effective repair solutions remain limited. This study addresses this challenge

In winter, the ice-covered conductors pose a significant influence to the safe operation of power grids. Despite extensive research in this area, measuring on-site ice accurately remains a major challenge. Obtaining accurate data of ice thickness and density is the basis of ice disaster prevention and emergency treatment of power grids. The current measurement methods based on power line's tension

Digital twin (DT) modelling is a prerequisite for the successful application of DT technology in the power industry. However, traditional scene modelling methods are costly, time-consuming, focus on overall features and lack real-time updates, hindering the interaction between DT models and physical power equipment scenes. Therefore, a scene DT modelling technique focusing on local features in risk

In the electric power equipment industry, various insulating materials and accessories are manufactured using petroleum-based epoxy resins. However, petrochemical resources are gradually becoming limited. In addition, the global surge in plastic usage has consistently raised concerns regarding greenhouse gas emissions, leading to worsening global warming. Therefore, to facilitate eco-friendly policies

Predicting the future health state of a transformer can offer early warning of latent defects and faults within the transformer, thereby facilitating the formulation of power outage maintenance plans and power dispatch strategies. However, existing prediction methods based on the structure of ‘splicing prediction and diagnosis method’ suffer from limitations such as inability to achieve global optimality

Arc flashes pose significant hazards to personnel working with energised power lines due to their high thermal risk, quantified by incident energy (IE) in joules or calories per area. Accurate estimation of IE is crucial for ensuring safety. The most widely employed method for estimating IE from an arc flash is outlined in IEEE Std 1584-2018, which applies exclusively to three-phase AC arc flashes

In this study, the authors proposed a promising structure design, the micro-crosslinked polypropylene (PP), to enhance the high-temperature energy storage density. With the grafting of 1,6,7,12-tetrachlorinated perylene-N-2-aminoethyl acrylate-N′-dodecylamine-3,4,9,10-tetracarboxylic bisimide (PTCDA) onto PP molecules, the obtained PP-g-PTCDA achieved a superior energy storage density of 2.34 J/cm3

Transformers are widely distributed and extremely important energy conversion equipment in the power system. However, the high altitude electromagnetic pulse (HEMP) can induce a steep pulse voltage with a peak value of up to thousands of kilovolts on the overhead line, and the frequency is up to 100 MHz, which is easy to damage the transformer and seriously threaten the safe and stable operation of

Metallised film capacitors (MFC) can operate under much higher voltage compared to the foil capacitor due to their self-healing (SH) properties, which caters to their application with high energy storage density requirement. Excellent results were achieved on the enhancement of the energy storage density of the dielectric material, whereas the SH properties of the modified material were less concerned

In this paper, for the first time, an experimental proof of concept for utilising time reversal (TR) in the acoustic regime to localise partial discharge (PD) sources was presented using a single sensor. To achieve this, an experimental setup comprising a water tank, acoustic transducers for signal transmission and reception, and 2D scanners was developed. The performance of the proposed method was

Metallised film capacitors (MFCs) are renowned for their unique self-healing (SH) properties, which bestow them with exceptional reliability and stability in the face of intense electric fields, high voltages, and pulse power applications. Nonetheless, the exploration of SH characteristics concerning single-layer dielectric film remains insufficient for advancing MFC reliability evaluation. To establish

Local ageing defects are the main causes of cross-linked polyethylene (XLPE) power cable faults. This research aims at assessing the severity level of typical cable local ageing defects based on the high-voltage frequency domain spectroscopy (FDS) non-linearity. Experimentally, typical XLPE cables ageing defect conditions are simulated, with different ageing types, degrees, and local proportions. Then

Ultra-high-voltage direct current wall bushings are critical components in direct current transmission systems. Temperature variations and abnormal distributions can signal potential equipment failures that threaten system stability. Therefore, monitoring these critical multi-point temperature variations is essential. However, the unique design of the bushings, featuring insulation sheds of periodic

In this paper, the effect of gamma-ray irradiation on the electrical conductivity of polypropylene (PP) composites has been studied. The samples are prepared using PP and styrene–ethylene–butylene–styrene elastomer with contents ranging from 0 wt% to 50 wt%, and exposed to Cobalt-60 gamma irradiation, with a dose from 0 to 250 kGy. Electrical conductivities at different temperatures and trap distributions

Diagnosing the operational status of High-voltage circuit breakers (HVCBs) is crucial for ensuring the safe and stable operation of the grid. Mechanical characteristic parameters are effective indicators for evaluating the performance of HVCBs. Recent studies have shown that the actions of the springs and cams in HVCBs can be used to detect the operational status of the mechanical mechanisms, which

This study provides comprehensive and quantitative assessments of the electrical insulation, viscosity, thermal conductivity, flash point, acidity, and stability of dielectric nanofluids. In the experiment, naphthenic mineral oil was chosen as the base fluid. MgO, Al2O3, and SiO2 were preferred as nanoparticles. In the dielectric breakdown voltage (BDV) tests performed, increased values were observed

With the enormous growth in the capacity of electrical equipment, power semi-conductor devices are developing rapidly towards larger size and higher capacity. To suppress the thermal resistance and achieve efficient heat dissipation, the authors focus on developing a low-temperature sintering technique for wafer-level high-power semi-conductor devices. In detail, a 6-inch whole-wafer device was successfully

As an important component of oil-immersed transformers, the bushing's internal insulation ageing and dampness after the long-term operation can cause changes in the internal electric and temperature fields, seriously threatening its safe operation. This paper tested the power frequency permittivity and direct current conductivity of aged and damp oil-paper insulation samples at different testing temperatures

To suppress the resistivity positive temperature coefficient (PTC) effect of ethylene-butyl acrylate copolymer (EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer, the polar molecule maleic anhydride (MAH) is grafted onto EBA macromolecules by melt blending and thermal grafting. The resistivity temperature stability of the grafted semi-conductive composites

C5F10O/CO2 gas mixture is one of the most promising alternatives to SF6 as an insulating gas in high-voltage switchgear. As a key performance index in product design, the temperature rise characteristics are rarely reported. In this paper, the thermodynamic parameters of C5F10O/CO2 gas mixture were calculated first. Then, the calculation model of transient temperature rise was constructed for a 252 kV/3150 A

Distribution transformers may experience insulation breakdown or degradation when exposed to the influences of high-altitude electromagnetic pulse (HEMP), thus posing significant threats and uncertainties to the safety and stable operations of power systems. Therefore, this study constructs a HEMP impact-test platform for distribution transformers, evaluates and analyses the development patterns of

Developing a stable insulation material stands as a crucial challenge for high-voltage direct current (HVDC) cable insulation. This work proposes an alloying strategy to significantly enhance the breakdown strength and high-temperature resistivity of cross-linked polyethylene (XLPE). The strategy involves blending low-density polyethylene (LDPE) with polystyrene (PS), resulting in a polymeric alloy

This research introduces an equivalent circuit model and a computational method to address complex mechanical motion issues through electromechanical analogies. The study initially refines core vibration characteristics using single- and multi-degree-of-freedom models, subsequently establishing equivalent circuit models for these various degrees of freedom. However, employing high degree-of-freedom

The characteristics of positive corona discharge of rod electrode in high-speed airflow are studied in this paper. The experiments were carried out in a wind tunnel with a maximum flow speed of 100 m/s in a dark room. The discharge voltage and current were recorded and the corona patterns were captured by a digital single lens reflex (DSLR) camera during the experiment. A discharge transition in rod

The arc faults inside oil-immersed power equipment can produce high-amplitude pressure waves inside tanks, which might cause ignition and explosion accidents. This kind of failure is one of the most severe faults for power equipment and has attracted considerable attention in recent years. However, due to the high risk of the experiments and the complex development of arc in oil, the characteristics

Currently, the design of transformers insulation predominantly depends on the allowable alternating current (AC) field values for insulating oil established by Weidmann in the 1980s, lacking the research under direct current (DC) voltage for converter transformers. This study selects naphthenic oils and paraffin-based oil transformer oil as research subjects, establishing a practical measurement platform

The adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover. However, there is currently a lack of a dynamic model that can reasonably explain the adhesion process of impurity particles, and the characteristics of particle adhesion are not yet clear, making it difficult to assess the risks of insulation contamination and

In urban power networks, a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels, primarily for reasons of installation convenience. In these situations, excessively high levels of sheath currents were often detected during routine inspections, but no electrical faults were found to be responsible. Previous publications ignored the

The authors aim to explore the effectiveness of two-component polyurea materials applied to transmission line towers (on the ground potential side) in improving the insulation performance of the conductor–tower gap. The physicochemical and electrical properties of the polyurea materials were first analysed and a conductor–tower gap testing platform was constructed to investigate the effects of the

Surface flashover is a gas–solid interface insulation failure that significantly jeopardises the secure operation of advanced electronic, electrical, and spacecraft applications. Despite the widespread application of numerous material modification and structure optimisation technologies aimed at enhancing surface flashover performance, the influence mechanisms of the present technologies have yet to

Layered epoxy/paper composites that exhibit excellent insulating characteristics under elevated electrification and temperature conditions are essential components for power system insulation. Yet, inevitable charge accumulation occurs at hetero interfaces between layers due to interfacial polarisation and interface barrier effect, bringing about local electric field distortion and potential risk of

The interturn paper insulation of oil-immersed power transformer windings, under the combined influence of electric fields, moisture, and conductor heating, will produce bubbles, which pose a significant threat to the insulation system. However, there is limited research on the characteristics of bubble evolution in oil–paper insulation under the influence of electric fields and the subsequent dissolution

The authors investigated the ingredient detection technique of silicone rubber based on the Terahertz spectrum. For this purpose, 18 diverse high-temperature vulcanised silicone rubber (HTVSR) formulations were customised, 8 of which are used as calibration set while the rest 10 as prediction set. Based on the Beer-Lambert Law, the partial-least-square (PLS) regression model and the least-squares support-vector

For the space charge measurement method with optical excitation for electrical insulation, the distortion of the excitation laser on the measurement signal and the accumulation of space charge have not been discussed before. Both experiment and simulation results show that three types of distorted components introduced by optical excitation can lead to distortion of the upper interface signal. Further

Insulation systems in high-voltage electric machines play a pivotal role in the reliable operation and longevity of the equipment. Mica-based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation degradation. Numerous qualifications tests, such as voltage endurance, are outlined in IEC and IEEE standards. The authors

Line-commuted converter (LCC)–voltage source converter (VSC) hybrid high voltage direct current (HVDC) transmission system is an innovative technology, the existing LCC and VSC protection require setting, and it is difficult to be directly applied in the LCC–VSC hybrid HVDC, which is a serious problem in practical engineering. A novel linear regression density peak clustering (LRDPC) approach is introduced

When some new-type sensors are subjected electromagnetic interference (EMI), the traditional standard can no longer serve as the guidance for their EMI protection. Therefore, it is necessary to evaluate the complexity of the new sensing equipment's suffering from electromagnetic interference. A hybrid method of feature extraction and complexity evaluation of Electromagnetic Interference signals based

Ultra-wideband (UWB) microwave sources driven by specialised pulsed power generators have experienced a considerable development in the last decade due to their wide domain of new applications such as defence or counter-terrorism activity. The authors present the main findings of a research dedicated to the development of a pulsed power-driven electromagnetic field source for disabling improvised explosive

C6F12O is proposed to be one potential eco-friendly insulation gas to replace SF6. However, the assessment of its decomposition properties and the compatibility with metal electrodes in discharge faults is still challenging, which greatly hinders the development of its insulation and arc-extinction applications. Herein, a theoretical method is proposed to reasonably address the discharge effects on

The cross-linked polyethylene insulated cables with corrugated aluminium-sheathed are widely used in urban power systems. Recently, a new type of power cable fault has emerged, primarily due to defects in the buffer layer. However, there is a notable lack of effective evaluation methods for these defects in high-voltage (HV) cables. Initially, a theoretical analysis of the gas generation mechanism

Understanding the impulse discharge behaviour of natural ester (NE) is crucial for its safe application in high-voltage transformers. The ionisation potential (IP) of triglycerides plays a significant role in the process of molecular ionisation during impulse discharge for NE. The correlation coefficients between molecular size, frontier orbital, electrostatic potential, polarity, and IP were analysed

Long-term exposure to moisture leads to a gradual deterioration of performance and reduced service life of glass fibre-reinforced epoxy resin (GFRP) material in composite insulators. Therefore, it is necessary to analyse the moisture absorption characteristics of GFRP material and the evolution of damage to their internal interface properties. Moisture absorption tests on GFRP rod material used in

The influences of thermal cycling ageing on structures and insulation performances of polypropylene (PP)/elastomer/boron nitride (BN) nanocomposites are investigated. The Melt blending method was used to prepare the nanocomposites, in which propylene-based elastomer (PBE) or ethylene-octene copolymer elastomer (EOC) was contained for comparison. Then, the samples were treated using a thermal cycling

The potential of using eco-friendly thermoplastic polypropylene (PP)-based insulation for high voltage direct current (HVDC) cable has been widely investigated but much less work on the PP-based semiconducting screen (SC). Considering a long service life (>30 years) under high temperature and high electrical stress is required for typical HVDC cables, and investigations on the effect of antioxidant

The real-time simulation of the modular multilevel converter-based high-voltage direct current (MMC-HVDC) transmission system has become a popular research topic. However, in order to meet the real-time performance, the real-time simulation technology will cause additional simulation errors for MMC-HVDC, especially on its frequency characteristics. Therefore, a parallel multi-rate simulation scheme

To solve the problem of the energy harvesting (EEH) effect of the condition monitoring devices power supply on the transmission line is not ideal. The authors designed three kinds of EEH schemes based on AC electric field induction, which can effectively improve the output power of load power supply. The EEH principle of each scheme was analysed in detail, and the influence factors such as the shape

The authors investigate the effects of nanofillers with varying band-gap energies on the space charge properties, breakdown field strength, and bulk resistivity of epoxy (EP)-based composites. Additionally, the molecular orbital distribution of both the epoxy resin and nanofillers were examined through density functional theory. Experimental results indicate that the space charge accumulation within