Electrical Substation Equipment Research Articles

Digital protection of electrical equipment in railway transport

In this scientific study, an analysis of the modernization of the digital protection of AC traction substation electrical equipment in operation, in particular power transformers, the implementation of the basic provisions for the implementation of digital protection of power transformers, finding algorithms for the implementation of both measuring and logic elements of digital protection, mathematical models of digital protection of power transformers are obtained, a method for blocking current protection is implemented, a method is selected finding the setpoints of the stage, obtaining differential protection, the schemes of secondary switching of digital protection are considered, the results of the scientific research carried out in the microprocessor terminal of protection of power transformers.

Numerical modeling for the seismic response of interconnected electrical substation equipment

Numerical modeling for the seismic response of interconnected electrical substation equipment

Comparison of Traditional Image Segmentation Methods Applied to Thermograms of Power Substation Equipment

The variation in the thermal state of electrical energy substation equipment is normally associated with natural wear or equipment failure. This can be detected by infrared thermography, but technically it demands a long time to analyze these images. Computational analysis can allow an automated, more agile, and more efficient analysis to detect overheated regions in thermographic images. Therefore, it is necessary to segment the region of interest in the images; however, the results may diverge depending on the technique used. Thus, this article presents the improvement of four different techniques implemented in Python and applied in a substation under real operating conditions for a period of eleven months. The performance of the four methods was compared using eight statistical performance measures, and the efficiency was measured by the runtime. The segmentation results showed that the methods based on a threshold (Otsu and Histogram-Based Threshold) were fast, with processing times of 0.11 to 0.24 s, but caused excessive segmentation, presenting the lowest accuracy (0.160 and 0.444) and precision (0.004 and 0.049, respectively). The clustering-based methods (Cluster K-means and Fuzzy C-means) showed similar results to each other but were more accurate (0.936 to 1.000), more precise (0.965 to 1.000), and slower, with 2.55 and 38.8 s, respectively, compared to the threshold methods. The Fuzzy C-means method obtained the highest values of specificity, accuracy, and precision among the methods under analysis, followed by the Cluster K-means method.

Novel Spiral-Gap Shielding Shell for a Rogowski Current Sensor

Rogowski current sensors play an important role in detecting the condition of electrical power substation equipment. An electromagnetic field shielding shell is necessary for some of these sensors to operate correctly, especially those with large diameters and small heights. These are used for frequency-response analysis in power transformers. In this study, the magnetic-shielding effectiveness of a normal C-type metal shell was tested and simulated. The distribution and direction of the magnetic field were analyzed using finite-element simulation calculations to reveal the reasons for its poor shielding effectiveness. It was found that the magnetic field induced by an interference current crosses the shell and enters its cavity through the gap in its inner wall. Shells with larger inner-diameter-to-height ratios have worse magnetic-shielding effectiveness. Therefore, a novel shell structure with a spiral gap is proposed here. The magnetic-shielding effectiveness of this new type of shell was analyzed by further simulations and verified in experimental tests. The results showed that a shell with a spiral gap has better shielding effectiveness when it has a long gap. In addition, the spiral gap was found not to inhibit the current-measurement function of the sensor. This provides a new approach to the design of electromagnetic shielding shells for Rogowski sensors.

Compilation of a Local Electrical Insulation Pollution Map in the Sheikh-Najar Industrial Region of Syria

A method for improving the performance reliability of electrical installations under the conditions of polluting the insulation of the 66 and 230 kV overhead lines (OHL) and outdoor switchgears (OSG) in the Sheikh-Najar industrial region near Aleppo, the economic capital of Syria, is considered. According to the relevant regulatory documents, the most efficient approach to selecting the insulation levels is the one based on compiling regional and local insulation pollution maps (IPMs) in the territory where the grid facilities are located. An electronic local IPM in the Sheikh-Najar industrial region was compiled using the characteristics of industrial pollution sources. The article presents the climatic characteristics of the Aleppo city area, the electrical circuit diagram and insulation characteristics of the existing 66 and 230 kV OHLs and OSGs, the characteristics of industrial pollution sources (in terms of produced goods types and amounts), estimated pollution degrees (PD) at various distances from the enterprise boundaries with a circular wind rose, and those adjusted for the real wind rose in the city of Aleppo, and the local IPM of the Sheikh-Najar region drawn using the AutoCAD software. It has been established that there are zones with insulation pollution degrees 2, 3 and 4 in the Sheikh-Najar industrial region territory. Based on the study results, recommendations have been elaborated for increasing the specific effective creepage distance of the OHL and OSG insulation by adding linear insulators to the strings, for choosing the optimal types of substation electrical equipment, and for taking preventive measures. To refine the boundaries of local IPM zones, it is recommended to study the features characterizing the pollution of electrical installations insulation caused by both industrial and natural factors, as well as to generalize the experience gained from the operation of electrical installations in the Sheikh-Najar industrial region.

Temperature prediction of substation equipment based on back-propagation neural network -simulated annealing

The substation is an important part of the smart grid. The stable operation of electrical equipment in the substation is related to the stability of the grid. According to the statistical results, among the common substation equipment failures, thermal failures have a larger proportion. Thermal faults can be monitored through the surface temperature of the equipment, and predicting the changing trend of the equipment temperature in advance is of great significance for reducing equipment faults in substations. For this reason, this paper proposes a method for predicting the temperature of substation equipment based on BP neural network-simulated annealing algorithm, using equipment parameters, environmental information parameters, etc. to predict the temperature of electrical equipment in the substation, so as to realize early warning of thermal faults in substation equipment. Through comparative analysis, it is verified that the method proposed in this paper can accurately predict the temperature of substation equipment, which provides strong guarantee and support for the safety management of substation electrical equipment.

Brief Analysis of Substation Electrical Equipment Installation Debugging and Operation Maintenance Technology

Brief Analysis of Substation Electrical Equipment Installation Debugging and Operation Maintenance Technology

Image-Based Incipient Fault Classification of Electrical Substation Equipment by Transfer Learning of Deep Convolutional Neural Network

A transfer learning-based deep convolutional neural network (DCNN) is employed in this article to identify several typical electrical substation equipment incipient faults. Image dataset contains 11 000 captured electrical substation equipment images, and each image inside the dataset was labeled as normal condition or typical incipient faults (insulation oil leakage, insulator contamination, rusting, and paint off). High-dimension features of electrical substation equipment images were first extracted by classical pre-trained DCNN architectures through the transfer learning method, and different incipient faults were then classified by the fully-connected (FC) neural network using the SoftMax activation function. Remarkable fault classification accuracy was obtained on the validation image, which verifies the effectiveness of the purposed method. Performances of various pre-trained classic DCNN architectures were explored and evaluated by t-distributed stochastic neighbor embedding (t-SNE) feature cluster maps, learning curves, and confusion matrixes. Results show that a model consists of MobileNetV2 DCNN architecture and two FC neural network layers could finalize fault classification tasks on 1000 images in 25 s with an accuracy of 98% which achieves better performance than traditional image classify methods. The proposed method could be useful for designing an electrical substation image monitoring system thus providing early prediction of incipient equipment faults.

Seismic Finite Element Analysis of Lightning Arrester Combination by Casing and Pillar Insulator

The seismic performance of electrical equipment in substations has a great impact on the normal operation of the whole substation. The results of the modal analysis show that the fundamental frequency of the three devices is in the range of 0.9Hz∼1.1Hz. The maximum stress of the casing for the three devices is respectively 55.43MPa, 45.39MPa, 35.26MPa, when the peak acceleration 0.4g seismic action is verified. The maximum stress of insulator is respectively 47.01MPa, 62.72MPa and 30.85MPa, and the maximum relative displacement of the top for the equipment is 617.2mm.

Research on path planning algorithm of intelligent inspection robot

With the development of intelligent inspection robot technology, inspection robots are widely used in substations to complete the inspection work of substations and move toward intelligent inspection. At present, substations begin to reduce the number of inspection personnel, reduce labor costs, and improve inspection efficiency and ensure the safe operation of electrical equipment in substations by using inspection robots to conduct intelligent inspection of substation equipment. The algorithm is used to realize the path planning of the inspection robot and model the substation environment.

Design of Distributed Substation High Voltage Electrical Equipment Online Monitoring System Based on Image Segmentation Technology

As an important support mechanism for real-time monitoring and display of system frequency, harmonic voltage, harmonic current, three-phase voltage unbalance, voltage fluctuation and flicker, true power factor and other power quality parameters specified in national standard, especially for fast and accurate data processing and improving test frequency and level, the online monitoring of substation is an important support mechanism for real-time monitoring and display of system frequency, harmonic voltage, harmonic current, three-phase voltage unbalance, voltage fluctuation and flicker, true power factor and other power quality parameters specified in national standard. The research of distributed substation high voltage electrical equipment online system based on image segmentation has important practical value. However, the design system of the online monitoring network of some substation electrical equipment can not effectively follow the development needs of society and industry, and there is an urgent need for effective reform. Based on this, this paper first analyzes the problems existing in the design system construction of online monitoring network of distributed substation electrical equipment, and then gives the construction strategy of online monitoring system of high voltage electrical equipment in view of these problems.

Genetic Algorithm-Based Strategy for Routing in Virtual Electrical Substations Aiming for Security / Estratégia baseada em Algoritmos Genéticos para o Roteamento em Subestações Elétricas Virtuais Visando a Segurança

Maintenance in electrical substation equipment in- volves several daily risks to the worker. When carrying out the maintenance of a large equipment, a truck is assigned to the task. It is not any place that the truck has the ability to travel, nor the workers have the free transition through the place. The objective of this work is to develop a Genetic Algorithm to solve the problem, to create a route where the level of danger is low and does not pose a risk to the health of the worker. To test the genetic algorithm, a substation virtual environment was used where the dimensions and distances are reliable for a real environment. In order to do so, the map division strategy and the creation of individuals with variable sizes were applied. The results were satisfactory, obtaining a route from the point of departure and the point of arrival.

A Method for Segmentation of Transformer Oil Level Region Based on Infrared Image

With the rapid development of computer and artificial intelligence technology, infrared images are playing a higher and higher value in the state monitoring of electrical equipment in substations. Aiming at the detection of the oil level area of the oil conservator in the substation, in order to accurately obtain the oil level information, this paper proposes a transformer oil level detection method combining maximum entropy threshold segmentation algorithm and SLIC (simple linear iterativeclustering) segmentation algorithm. First, the original infrared image is pre-processed by image cutting technology to obtain the infrared image of the oil pillow area; the green channel image is extracted, and then the infrared image is segmented by the maximum entropy threshold segmentation algorithm to remove the background interference and obtain the target area of the electrical equipment. Finally, SLIC is used to super the pixel segmentation algorithm performs segmentation to obtain the oil level area. Experiments show that the algorithm can clearly segment the oil level area of the oil pillow, and it has certain practical value.

THE ABILITY OF MODERN TECHNOLOGIES TO INFLUENCE THE NEUTRAL MODE OF ELECTRIC GRIDS

In this article, we consider the modes of neutrals of 0,38 to 750 kV networks. In any network with different voltage classes, the neutral point of a power transformer winding can operate both in isolated and deaf earthed mode. However, the choice of this mode depends on economic feasibility.
 The paper presents arguments and advantages of application of system with isolated and compensated neutral of networks with voltage classes 6–35 kV. For networks of these voltage classes various options of connecting arc suppression reactors with step and smooth regulation, as well as low and high impedance resistors in the neutral point of neutralizing transformer or zero sequence filter are considered. On the example of operation of electric networks of the Republic of Chuvashia for many decades it is emphasized that compensation of capacitive currents with arc suppression reactors is an effective and reliable way to protect not only substation electrical equipment from overvoltage, but also to ensure electrical safety of people and animals, as well as reinforced concrete towers from destruction.
 It is noted that the 6–35 kV networks in the future can be made with deaf earthed neutral. However, this will be possible under the condition that self-supporting insulated wires will be installed on overhead transmission lines instead of bare wires, and cross-linked polyethylene cables will be used on cable lines. It is emphasized that the introduction of work under voltage in 6-35 kV networks and digitalization of substations with the widespread introduction of microprocessor technology will accelerate the transition from a system with insulated (or compensated) neutral to a deaf earthed system. Nevertheless, the decision to switch from the insulated neutral system to a deaf earthed system will remain the prerogative of the design organization based on the specifics of the electrical equipment and the sphere of industrial activity.

Thermal Fault Diagnosis of Electrical Equipment in Substations Based on Image Fusion

Infrared thermal imaging can diagnose whether there are faults in electrical equipment during non-stop operation. However, the existing thermal fault diagnosis algorithms fail to consider an important fact: the infrared image of a single band cannot fully reflect the true temperature information of the target. As a result, these algorithms fail to achieve desired effects on target extraction from low-quality infrared images of electrical equipment. To solve the problem, this paper explores the thermal fault diagnosis of electrical equipment in substations based on image fusion. Specifically, a registration and fusion algorithm was proposed for infrared images of electrical equipment in substations; a segmentation and recognition model was established based on mask region-based convolutional neural network (R-CNN) for the said images; the steps of thermal fault diagnosis were detailed for electrical equipment in substations. The proposed model was proved effective through experiments.

Study on Dynamic Amplification Factor of UHV Pillar Equipment

In the research of UHV pillar equipment, the dynamic amplification factor of bracket is a key parameter. This paper mainly focuses on the relationship between the dynamic amplification factor of ceramic equipment under the condition of seismic acceleration response spectrum when the structural parameters of the bracket are the same. In this paper, the stiffness of the bracket is changed by altering the elastic modulus of the steel. The dynamic amplification factors of the speed, displacement, stress and acceleration of the bracket in the two kinds of overall structures are compared and analyzed by numerical simulation. At the same time, the relationship between the bracket frequency and the steel consumption is compared by calculating the steel consumption of different bracket structures. Based on the results of simulation analysis and considering the seismic design of porcelain electrical equipment in UHV substations and converter stations, it is suggested that the dynamic amplification factor, the envelope of displacement and stress amplification factor of 1.40 should be adopted, thus providing a theoretical basis for the design of UHV bracket equipment.

Seismic Evaluation Method of UHV Transformers for Soil-structure Interaction

China is an earthquake-prone country. In recent years, Wenchuan earthquake and other earthquakes have caused serious damage to power facilities. As the most important electrical equipment in UHV substations, transformers are facing great threat of earthquake disasters. Currently, seismic evaluation of UHV transformers does not consider soil-structure interaction, which is not conducive to fine seismic design and evaluation of UHV transformers. Based on the structural features of the UHV transformer equipment, the seismic evaluation method of the UHV transformer with soil-structure interaction is proposed in this paper, which provides a basis for the seismic performance evaluation of the UHV transformer.

Characterization of nano-additive filled epoxy resin composites (ERC) for high voltage gas insulated switchgear (GIS) applications

Abstract Insulation based on epoxy resin (ER) is widely used for high voltage and high fault current rated electrical substation equipment. This paper details the formulation of epoxy based Nano-composites and influence of the Nano filler material on the electrical and thermal properties like breakdown voltage (BDV), relative permittivity, tanδ and thermal conductivity of the epoxy resin composites (ERC). The nano-filler materials such as alumina (Al2O3), silica (SiO2) and titania (TiO2) are considered for the study. Diglycidyl ether of biphenyl-A (DGEBA) type epoxy resin CY5950 and acid anhydride hardener HY5951 are used for development of samples/insulated spacers. Scanning electron microscopy (SEM) images have been established for various ER composites to understand how the dispersion of nano-filler material influences the performance parameters of the samples. In the present study, the sample preparation with metallic inserts has shown additional advantages compared to existing practice of purely insulated samples. Developed samples help to estimate electrical and mechanical properties more accurately. Most appropriate nano filler is identified based on the test results obtained on samples developed in the study. Finally, by using the identified epoxy–filler composite, insulated spacers for 145 kV GIS have been developed and evaluated for electro-mechanical parameters. Necessary dielectric tests have been carried out on developed insulated spacer as per IEC.

Friction pendulum test and parameter optimization for the vibration reduction of a 100 kv isolating switch

An earthquake is a natural disaster with a high destructive force. According to previous history, a great many power grid facilities are damaged during the earthquake, and the damage to electrical equipment in substations are often very serious. This article takes the isolating switch in the substation as an experimental object. Firstly, the friction pendulum for vibration isolation is designed and manufactured according to the numerical simulation, and then the seismic test and vibration isolation test of the high voltage isolating switch are designed. The input waveforms and input acceleration intensities of the seismic test were designed experimentally. The test data of the isolating switch under the seismic condition and the vibration isolation condition with the friction pendulum vibration isolation system installed are mainly investigated. The measured acceleration of the top of the isolating switch bracket is used to compare and analyze the vibration isolation performance of the friction pendulum. Then, it can be seen that the friction pendulum system has the vibration isolation effects on the isolating switch. Especially, the isolation effects of friction pendulum are better when the acceleration intensity become higher. In order to obtain a better curvature radius and friction coefficient of the friction pendulum, based on the results of this test, the systematically numerical simulation tests for optimization on the friction pendulum vibration isolation system are conducted. The simulated top displacement of the isolating switch and the stress change of the root of the porcelain bottle were obtained. By comparing the vibration isolating performance of the friction pendulum under different parameters, numerical simulations show that the vibration isolation performance of the friction pendulum is better when the radius of curvature is 1200 mm and the friction coefficient is 0.04. The numerical results demonstrate that reasonable design of friction pendulum parameters can play a significant role in isolating vibration for power equipment.

Relationship between Damage Rate of High-Voltage Electrical Equipment and Instrumental Seismic Intensity

Based on the actual damage data of high-voltage electrical equipment in electric substations in the Wenchuan earthquake, this paper uses the cumulative Gaussian distribution function to describe the relationship between the damage rate of high-voltage electrical equipment and the instrumental seismic intensity. The instrumental seismic intensity at strong motion observation stations in the Wenchuan earthquake is calculated, and the Kriging interpolation method is used to estimate the instrumental seismic intensity at 110 kV and above voltage level substations in Mianyang, Deyang, Guangyuan, and Chengdu of Sichuan Province. A cumulative Gaussian distribution function is then used to fit the damage rate-instrumental seismic intensity relationship curve for six types of high-voltage electrical equipment such as the transformer, circuit breaker, voltage mutual inductor, current mutual inductor, isolating switch, and lightning arrester. The results show that transformers have the highest vulnerability during earthquakes, and they suffered a certain level of damage even under low instrumental intensity. The second most vulnerable equipment is the circuit breaker, followed by the lightning arrester, transformer, and isolating switch, which share a similar vulnerability curve.