Metal Oxide Surge Arresters Research Articles

Effect of Co-Doping of Al3+, In3+, and Y3+ on the Electrical Properties of Zinc Oxide Varistors under Pre-Synthesizing BiSbO4.

Under the premise of using the solid-phase method to pre-sinter Bi2O3 and Sb2O3 into BiSbO4 as a substitute for equal amounts of Bi2O3 and Sb2O3 in the formula, the effects of co-doping with In(NO3)3, Al(NO3)3, and Y(NO3)3 on the microstructure and electrical properties of ZnO varistors were studied. The experimental results show that with an increase in In3+-doped molar concentration, the leakage current of the ZnO varistor shows a rapid decrease and then a slow increase trend. However, the nonlinear coefficient is the opposite of it. With the combined effect of the rare earth element Y3+, the average grain size is significantly reduced, which leads to an increase in the voltage gradient. At the same time, a certain amount of doped In3+ and Al3+ is dissolved into the grains, resulting in a decrease in grain resistance and thus a low level of residual voltage. The varistor with 0.6 mol% In3+, 0.1 mol% Al3+, and 0.9 mol% Y3+ doping ratios exhibits excellent overall performance. The nonlinear coefficient is 62.2, with the leakage current being 1.46 µA/cm2 and the voltage gradient being 558 V/mm, and the residual voltage ratio is 1.73. The prepared co-doped ZnO varistors will provide better protection for metal oxide surge arresters.

New criteria for metal oxide surge arrester condition monitoring based on leakage current analysis: Considering non‐uniform pollution effect

AbstractThe role of surge arresters is vital in power systems' protection against transient overvoltages, which can arise due to occurrences like lightning strikes or switching operations. Based on the performance of the surge arrester, assessing its condition is an essential requirement for early detection of any damage or deterioration. This article proposes innovative criteria based on the surge arresters’ leakage current analysis for the classification of uniform and non‐uniform pollution levels. The leakage current signal of clean, uniform, and non‐uniform polluted surge arresters has been examined under different contamination levels, humidity, and non‐uniformity degrees. Based on the experimental results analysis, a new criterion has been proposed for assessing the surge arrester condition, which has resulted from the fifth and first‐order harmonics ratio of resistive leakage current. Analysis of the proposed criterion demonstrates that this index has a significant correlation to the pollution level. The proposed criterion ability has been established based on random forest, support vector machine, decision tree algorithm, and multi‐layer perceptron in Python language. The obtained criterion based on experimental data in different conditions has been employed for classifier training, which can be applied in the power network for better condition monitoring of surge arresters ensuring fast and accurate outcomes.

A Bibliometric and Comprehensive Review on Condition Monitoring of Metal Oxide Surge Arresters.

This paper presents a literature review on the subject of Condition-Based Maintenance of surge arresters. Both a bibliometric analysis and traditional comprehensive research are presented. The bibliometric analysis is useful for obtaining insights about the literature. It quantitatively highlights relationships between journals, authors and keywords (related to the monitoring methods) and reveals future trends for research based on the timeline of the keywords. The traditional comprehensive literature review is also presented. It summarizes the methods, their advantages and disadvantages and also points to some known measurement issues of the methods. Both online (leakage current, harmonic components, temperature, partial discharges, power loss and the counting of discharges) and offline (reference voltage, residual voltage, insulation resistance, polarization/depolarization, return voltage, microscopy, spectrometry, X-ray, RUS and the recent application of FRA) methods have been qualitatively analyzed.

Analysis and mitigation techniques of overvoltages due to insulator transient arcs clearing on a 500 kV OHTL

In high-voltage OHTL, Overvoltages and arc currents due to insulator transient arcs clearing severely affect the stability of power systems.In this paper, a 500 kV Egyptian OHTL was simulated using ATP-EMTP software package. The insulators transient arcs clearing of the system were tested under different impedances of tower footing, locations of insulator arc tower, angles at which the arc initiate. Additionally, the effects of the corona phenomenon were taken into account to achieve realistic study. Furthermore, these factors thoroughly were analyzed to determine worst-case scenarios. Also the paper evaluated the performance of the overvoltage mitigation methods based on the installation of neutral shunt reactors, MOSA (Metal Oxide Surge Arresters), or combinations of both.The results demonstrated that the combination of MOSA and neutral shunt reactors was the most effective mitigation technique, reducing overvoltages by approximately 57.4 %, arc currents by 80 %, and arc extinction time by 27.3 %Notably, the most severe overvoltages and peak arc currents occurred at an angle of θ = 180° and footing impedance 30Ω. Additionally, the corona phenomenon played a role in reducing the severity of overvoltages, arc currents, and arc extinction time by approximately 56 %, 56 %, and 1.8 %, respectively. Finally, These findings provide valuable recommendations for mitigating overvoltages, arc currents, and arc extinction time during insulator arc clearing events.

Detection of Failures in Metal Oxide Surge Arresters Using Frequency Response Analysis

This work presents an innovative application of Frequency Response Analysis (FRA) in order to detect early degradation of Metal Oxide Surge Arresters (MOSAs). This technique has been widely used in power transformers, but has never been applied to MOSAs. It consists in comparisons of spectra, measured at different instants of the lifetime of the arrester. Differences between these spectra are an indicator that some electrical properties of the arrester have changed. An incremental deterioration test has been performed on arrester samples (with controlled circulation of leakage current, which increases the energy dissipation over the device), and the FRA spectra correctly identified the progression of damage. Although preliminary, the FRA results seemed promising, and it is expected that this technology could be used as another diagnostic tool for arresters.

Modelling of Low-Voltage Varistors’ Responses under Slow-Front Overvoltages

In this study, commercially low-voltage MOVs are exposed to switching surges to analyse and model the relationship between the number of surges and the MOV grain barrier height response. Repeated slow-front overvoltage transients are used to degrade the protective qualities of metal oxide surge arrester devices, affecting their reliability and stability. A total of 360 MOVs with similar specifications from three different manufacturers are degraded under switching surges at a constant temperature of 60 °C. The reference voltage and C-V characteristics of MOVs are measured before and after the degradation process to analyse the MOVs’ conditions. Grain barrier heights are determined from the C-V characteristics curve. An F-statistical analysis is then applied to analyse the effects of number of surges on the grain barrier height. The T-test is used to assess the statistical difference between the tested groups. Linear regression analysis is then applied to model the relationship between the number of surges and MOV grain barrier height. The results obtained show that the number of surges has a significant impact on grain barrier height. MOV grain barrier height is found to decrease as the number of surges applied increases. Regression models obtained for the tested MOV groups across all three manufacturers agree and indicate that the reduction in grain barrier height results from an increased number of surges. Regression coefficients of a developed model indicate that for one surge applied, the MOV grain barrier height decreases by 0.024, 0.055, and 0.033 eV/cm for manufacturers X, Y, and Z, respectively. Therefore, there is a linear relationship between grain barrier height and the number of applied switching surges.

Alleviation of the transients induced in large photovoltaic power plants by direct lightning stroke

Lightning strokes are considered the most common passively effective cause on the photovoltaic (PV) power plants compared to the other internal faults. In this paper, a 1 MW solar PV grid-connected power plant was studied. Lightning strikes were applied at different positions in the grid to test its effect on the PV farm’s components with the variation of the strike’s position. Also, it was studied the effect of lightning on the PV plant elements with the variation of lightning characteristics. Different mitigation techniques are applied such as choosing of metal oxide surge arrester (MOSA) with a suitable rating, designing high voltage filter (HVF), and parallel combination between them. The modeling and analysis were implemented by using PSCAD/EMTDC software. The results show that when the lightning stroke had been applied nearby the grid’s inverter position, it negatively harmed the PV farm by about a 16.1 % increase in peak voltage. As, either of the lightning characteristics increase, their effect appears negatively over all the system’s components especially the tail time parameter when it increases from 50 µs to 300 µs, it caused an increase in the peak voltage value at the striking position by 71.7%. Finally, the parallel combination between using MOSA and HVF represents an efficient mitigation technique for the lightning stroke over the solar farm totally with a reduction percentage of 96.3% than using MOSA only and 95% than using just HVF. Therefore, it effectively reduces the maintenance and replacement cost for the expensive components in the PV grid-connected plant.

Harmonic Analysis of Metal Oxide Surge Arrester Leakage Current Considering Fan-Shaped Type Pollution Effect

Harmonic Analysis of Metal Oxide Surge Arrester Leakage Current Considering Fan-Shaped Type Pollution Effect

A Survey of Diagnostic and Condition Monitoring of Metal Oxide Surge Arrester in the Power Distribution Network

Metal oxide surge arresters (MOSAs) are a popular solution for dealing with overvoltages due to lightning and switching in power distribution networks. As a result, a MOSA’s performance and longevity have a significant impact on the quality of energy and the frequency of outages. A MOSA performance is determined by several elements such as leakage current, partial discharge, and thermal image measured in various ways. In this study, different techniques for diagnostic and condition monitoring of MOSAs are discussed, and each method’s advantages and disadvantages are investigated. Additionally, the results of practical tests on two 20 kV healthy and degraded MOSAs are investigated and compared.

Analysis of Thermal Effects for Polymer-Housed Metal-Oxide Surge Arrester Under Multiple Strokes

Multiple strokes are the main factors affecting the safe and stable operation of power equipment. As the core lightning protection equipment, arresters are also frequently thermally collapsed due to multiple strokes. This paper investigates thermal effects of polymer-housed metal-oxide surge arrester (PMOSA) under multiple strokes. The comparative experiments of PMOSA lightning impulse are carried out through multiple strokes of experiment platform, including continuous lightning stroke and multiple strokes. Furthermore, the temperature distribution of the housing surface is obtained by infrared imager for thermal effect analysis. Subsequently, some typical DC parameters are tested to explore the association of impulse aging and thermal effects of the arrester under multiple strokes. Finally, a thermal-electric coupling model (TECM) is constructed to investigate the influence of some factors on the temperature of PMOSA from the perspective of materials and structure. The research in this paper can provide a theory reference and brief data support for improving the heat dissipation performance of arresters under multiple strokes based on structural optimization design and material modification.

Power Quality Problems Due to Transformer Inrush Current

Transformer energization can produce a large nonsinuoidal inrush current which contains both odd and higher order harmonic components that can put transformer winding under mechanical stress. Additionally, they can cause irregular tripping of harmonic protection relays. Furthermore, in relatively weak power systems, such as is the Bosnian system, the superposition of harmonic components with system resonance frequencies may produce temporary overvoltages (TOV). Transformer winding failures and metal oxide surge arrester (MOA) energy stresses can occur due to TOV. The paper demonstrates a case study of an energization of a 220/110 kV transformer and power quality problems that can appear due to higher harmonics. Energy stresses of MOA provoked by transformer energization are considered in the paper.

DECREASING BACKFLASHOVER NUMBERS ON MEDIUM VOLTAGE OVERHEAD LINES LOCATED IN REGIONS WITH HIGH SOIL RESISTIVITY

The possibility of decreasing backflashover numbers on medium voltage overhead lines located in regions with high soil resistivity has been analyzed in this paper. Until now, activities in this field of protecting overhead lines have been limited by existing surge protection equipment and possibilities of grounding systems. The possibility of using chemical rods for getting better ground resistance and introducing metal oxide surge arresters like line arresters alongside the medium voltage overhead lines is analyzed here. The idea of this paper is based on facts that metal oxide surge arresters have become very high quality products with low prices, and so many important experiences in using them like line arresters exist in the world; and we, in Croatia, have a 10-year-old experience in using chemical rods like part of grounding system. The paper treats the problems of backflashover on medium voltage overhead lines, chemical rods working principles and ways of designing grounding systems like this. Finally the techno – economic analysis of using chemical rods and metal oxide surge arresters possibilities has been made, with determining justifiability criteria of using them. In the conclusion, comparison with knowledge until now has been made, as well as a suggestion for future use.

Estimation of Metal Oxide Surge Arresters' Useful Life Based on Time Series Forecasts

Estimating equipment useful life has been a challenge over the years. In this work, a methodology based on the application of a combined time series forecast model composed of the adaptive neuro-fuzzy inference system (ANFIS) and support vector machine for regression (SVR) is proposed to be used in the determination of metal oxide surge arresters’ (MOSAs’) useful life. For this purpose, field measurements were performed in order to build a time series database composed of values of the leakage current third harmonic component, considering that this component is one of the indicators of the MOSAs’ degradation level most used in arresters’ monitoring. Subsequently, the forecasting models (ANFIS and SVR) were implemented. Then a combined model was proposed using the obtained results of those models. The performance of each implemented models was evaluated using three types of errors: MSE, MAE, and MAPE. After of the models’ evaluation, the useful life estimation of the MOSA was carried out using the proposed model. Considering the obtained results, the forecasts using the combined model were more accurate than those provided by the models based on ANFIS and SVR. Thus, the proposed model was used to estimate the MOSA's useful life.

A Novel Approach to Estimate the Quantity of Ingressed Moisture Content Inside Metal Oxide Surge Arrester Using Dielectric Modulus Technique

In this article, a novel technique is proposed for the estimation of ingressed moisture content inside metal oxide surge arrester (MOSA) in service. For the estimation of ingressed moisture content inside a dielectric precisely, knowledge of frequency domain spectroscopy (FDS) characteristics can be useful. However, in traditional FDS measurement, dielectric relaxation characteristics cannot be properly understood due to electrode polarization effect. Therefore, to overcome this problem, dielectric modulus technique is applied in this work. Dielectric modulus can uncover the relaxation characteristics in a dielectric, which is obscured by electrode polarization effect. Therefore, frequency variation of complex dielectric modulus characteristics of MOSA at different ingressed moisture content is analysed using Havriliak-Negami (H-N) relaxation model to investigate the changes in dielectric relaxation behavior with moisture ingression. The findings of the paper reveal that empirically obtained relationship between ingressed moisture content and H-N model parameters can estimate the ingressed moisture content inside a MOSA with an acceptable accuracy.

Cross Spectrum Aided Surface Condition Assessment of Metal Oxide Surge Arrester Employing Convolutional Neural Network

This paper proposes an automated framework for surface condition assessment of metal oxide surge arresters (MOSA) employing cross-wavelet transform (XWT) of the leakage current and convolutional neural network (CNN). XWT is performed between different contaminated leakage currents with an uncontaminated leakage current. A set of cross-wavelet spectrum (XWS) images are obtained after XWT. The XWS images are fed to the proposed customized CNN model for classification of MOSA surface contamination levels. The performance of the proposed CNN model is also compared with two benchmark CNN architectures namely AlexNet, VGGNet16. It is observed that the proposed model delivers better performance and offers significantly reduced computational burden compared with the existing benchmark CNN models. The proposed method can be applied for surface condition monitoring of MOSA in real-life.

Fusion of Deep Features With Superpixel Based Local Handcrafted Features for Surface Condition Assessment of Metal Oxide Surge Arrester Using Infrared Thermal Images

This letter presents an innovative approach to sense surface contamination severity of in-service metal oxide surge arrester through combining handcrafted and deep learning-based features. For this purpose, different color regions in the captured infrared thermal (IRT) images are isolated to generate superpixel regions through grouping of informative and meaningful pixels. Thereafter, handcrafted color features are extracted from each superpixel region. Additionally, the IRT images are analyzed through pretrained “ResNet50” deep architecture, and deep features are extracted. Thereafter, handcrafted color features and deep features are combined and fed to a classifier for classification of different surface contamination severity. The findings of this letter indicate that the proposed fusion strategy strongly boosts the classification performance compared to each stand-alone approach. Therefore, proposed framework with feature fusion strategy can be implemented for surface condition assessment of metal oxide surge arrester is service.

A novel technique for condition monitoring of metal oxide surge arrester based on fifth harmonic resistive current

The ageing in metal oxide surge arresters (MOSAs) is monitored by measuring their leakage current parameters. Particularly, the third harmonic component of resistive leakage current is directly correlated with the ageing and degradation of the arrester. However, the third harmonic of resistive current (IR3rd) is also affected by the third harmonic component in the grid's voltage. Therefore, IR3rd based monitoring may lead to an inaccurate condition assessment of MOSA when the supply voltage comprises third harmonic content. Hence, this paper introduces the fifth harmonic of resistive current (IR5th) as a new ageing indicator for MOSA. This study has been done experimentally on five samples of aged polymeric MOSAs rated at 120kV. Results have shown that the IR5th exhibits similar sensitivity towards ageing as compared to the IR3rd. Additionally, it has been found that the variation in IR5th with the fifth harmonic voltage is smaller than the variation in IR3rd with the third harmonic voltage. Therefore, the following technique can support the online condition monitoring of MOSAs in a more realistic way than the existing third harmonic current measurement technique.

Machine Learning MOSA Monitoring System

This research paper deals with the problem of Metal-Oxide Surge Arrester (MOSA) condition monitoring and a new methodology in surge arrester monitoring and diagnostics is presented. A machine learning algorithm (back propagation regression) is used to estimate the non-linearity coefficient of the surge arrester, based on operating voltage and leakage current of the arrester. Using a simulated system, this research investigates the possibility of application and efficiency of machine learning. It is shown that the applied learning algorithm results are competitive with the model results parameters calculated as R2 = 0.999 and mean absolute real error computed as 0.005 which has shown that the proposed model can be used for MOSA monitoring and diagnostic purposes.

Various Methods for Measurement of Resistive Leakage Current of Metal Oxide Surge Arrester

Metal Oxide Surge Arrester (MOSA) does not require any ordinary maintenance. But MOSA is get affected from ageing due to the effect of discharging impulse currents, uneven heating and internal partial discharges. A leading cause of deterioration is ingress of moisture. The degradation of MOSA also correlated with the ageing level of the arrester. This is called degradation under surge. The ageing level with the degradation of MO surge arrester or the leakage current of the surge arrester is related to each other. The leakage current is directly proportional to the ageing level. If the ageing level is raise, the leakage current also will increase. So, various methods for determination of the condition of ZnO surge arrester by means of measurement of the arrester leakage current are discussed. A MSCM method, which is based on leakage current of the surge arrester presented. The measuring instrument Leakage Current Monitor is also discussed.

Design of a Lightning Protection System for an Overhead 3 kV DC Electrified Railway Line: A Case Study from South Africa

A protection scheme is proposed for the 3 kV DC railway, in Kwa-Zulu Natal province, a region with a high lightning occurrence density. The surge protection was sought by implementing three metal-oxide surge arresters and an overhead ground wire. The purpose of these arresters is determined by their location in the circuit and the points that are vulnerable to adverse lightning effects: an arrester is installed to protect insulators between overhead lines and the supporting metallic mast, an arrester is installed to protect the point of contact between a stationary power supply wire and the train, and an arrester is installed to protect apparatus associated with the running tracks (return rail). An isolated earthing system is explored, and the effects of surge impedances and footing resistances are discussed. The voltage dropped across relevant vulnerable components and energy absorbed by the system components are determined by the simulation software Simulink. These results are compared with a railway system outfitted with the designed lightning protection mechanisms. Lightning currents are injected into the system using Heidler function where the parameters are in compliance with lightning protection standards. It is observed that the protection mechanisms defend susceptible components to a specified level. This demonstrates the success of the design in accordance with arrester protection levels (73.3 kV) and equipment withstand capabilities (a basic insulation level of 143 kV). This offers a protection margin of 95%. The largest percentage overshoot in the system is 39%, and this value is substantiated using reflection phenomena.