Performance Of Electrical Equipment Research Articles

An Experimental Analysis of Three-Phase Low-Voltage Power Factor Controllers Used in a Deforming Regime

In industry, to improve the power factor in low-voltage power substations, a power factor controller (the most used method) can be installed which connects capacitors banks (connected, or not, with coils) in the electrical installation. The most important parameters of power engineering are the power factors that indicate the efficiency of energy use. Currently, many non-linear consumers (more single-phase than three-phase) are used on low voltages. Harmonics (currents and/or voltages) are the most important dynamic component of power quality, affecting electrical equipment performance and also reducing power factors. The purpose of this analysis is to increase the displacement power factor and to decrease the total harmonic distortion (for the current) in the conditions where there are linear and non-linear consumers, where the power factor must be improved with capacitors banks. Relevant different consumers have been selected for both the industry and the home sector, as follows: inductive motors that are linear, inductive consumers, compact fluorescent lamps that are non-linear, and capacitive consumers. This analysis was carried out depending on the number of steps used for the power factor controller, the values of the capacitors banks, the AC reactor (connected in series with all consumers), and the LC shunt filters. For a slight deformation regime, a large number of capacitors banks with different values ensure a finer adjustment of the displacement factor. The maximum number of steps that regulators can command should not necessarily be used (the reliability of the installation decreases with the increase in the number of capacitors banks), but a reduced number of steps can be used, which can lead to higher values of displacement power factors. To improve the deforming regime and to increase the displacement power factor, the use of LC shunt filters, connected to a small number of steps, will also increase the displacement power factor (over 0.9) and decrease the total harmonic distortion (up to 7–10%) for the current. Weaker results were obtained with AC reactors connected to the power supply phases of consumers and, if a larger number of stages were used, to which LC shunt filters were connected, these filters become difficult to calibrate (resonances occur).

Experimental study on the thermal decomposition of epoxy/anhydride thermoset matrix in composite insulator core rods

Epoxy/anhydride thermoset matrix within composite insulator core rods may thermally decompose by temperature rise caused by partial discharge. The thermal decomposition characteristics of the epoxy/anhydride thermoset was analyzed using pyrolysis-gas chromatography-mass spectrometry (PY–GC–MS) from 200 to 1000 °C, including the mechanisms of crosslinked network scission and the formation of gaseous or liquid products with potential secondary effects on surrounding materials. Below 360 °C, scission at crosslinking points predominates by ceiling temperature behavior, forming anhydrides. Above 380 °C, scission of main chains leads to the production of corresponding fragments. Beyond 600 °C, decomposition of anhydrides and fragments from main chains leads to the formation of lower molecular weight substances. During the pyrolysis process, organic acids are formed from 240 °C to 1000 °C. Above 600 °C, gases with high vapor pressures and liquids that can induce swelling are produced. These byproducts can have secondary effects on surrounding materials, including the failure of interfacial adhesion, swelling of silicone rubber sheaths, and a reduction in the mechanical strength of glass fibers. Consequently, these effects may accelerate the decay-like deterioration of core rods, characterized by a surface morphology reminiscent of rotting wood. These findings will inform the optimization of materials for enhanced electrical equipment performance and facilitate the evaluation of potential environmental impacts posed by the thermal decomposition of epoxy/anhydride thermosets in future applications.

THERMAL CONDUCTIVITY MODELING OF DIELECTRIC OILS-BASED NANOFLUIDS USING THE FINITE ELEMENT METHOD

The enhancement of the thermal conductivity of dielectric oils has a positive effect on the performance of electrical equipment that uses these oils as a cooling medium. Nanofluids (NFs) have inspired high-voltage engineers to use them as alternative fluids in power transformers due to their impressive heat transfer and insulation compared to traditional dielectric oils. The present study is a numerical simulation by COMSOL Multiphysics of the thermal conductivity of NFs based on dielectric oils used in power transformers, to identify the effect of temperature, the concentration of nanoparticles (NPs), type of insulating fluid and NPs on thermal conductivity. The NFs were modeled inside a cube using the finite element method (FEM) by applying a temperature gradient. Several types of NPs were used (SiC, ZnO, TiO2, and Al2O3) in addition to several volume concentrations (0%, 0.001%, 0.002%, 0.01%, and 0.02%). The results showed a significant improvement in the thermal conductivity of the NFs with increasing concentration since the best results were recorded at an estimated volume concentration of 0.02%, while the lowest results were obtained for samples using a volume concentration estimated at 0.001%. The base fluid (BF) type and NPs play a dominant role in the thermal performance of the NFs, as the vegetable oil-based nanofluid provided the highest thermal conductivity values and silicon carbides (SiC) was the best NPs used in this study. However, a decrease in thermal transfer capacities was observed for all samples with increasing temperature.

The Interfacial Thermal Resistance Properties Of GNPs/Epoxy Thermally Conductive Composites By Molecular Dynamics Simulation

With the increasing power density and integration degree of electrical equipment, the problem of excess heat production is serious. Existing data show that the thermal management capability of electrical equipment is a key factor affecting the performance of electrical equipment. Therefore, the development of high thermal conductivity composites is an effective solution to improve the thermal management ability of equipment and extend the working life of equipment. With the purpose of enhancing the heat conduction of epoxy resin, graphene sheets (GNPs) with high thermal conductivity were added. Based on the reverse nonequilibrium molecular dynamics simulation (RNEMD) method, the thermal conductivity simulation of epoxy resin equipped with GNPs was carried out. The simulation results showed that the heat conductivity of epoxy resin equipped with GNPs had been greatly improved.

Study on Mechanical Properties of Friction Pendulum Isolation Device for Transformer

Electrical equipment has high vulnerability under strong earthquakes due to its own material and structure characteristics. The seismic performance of electrical equipment can be effectively improved by installing isolation devices. Based on the finite element simulation, this paper establishes the finite element simulation model of the friction pendulum isolation device suitable for the main transformer electrical equipment, calculates and compares the mechanical response of the isolation device under different design parameters. The results show that the friction pendulum isolation device with conventional design can meet the load-bearing requirements of the main transformer under conventional conditions; increasing the friction coefficient can effectively improve the energy dissipation effect of the friction pendulum isolation device, but the increase of the friction coefficient will limit the design displacement of the isolation device, and the specific isolation effect needs to be further evaluated; changing the curvature radius of sliding surface has little effect on energy dissipation of friction pendulum isolation device. The research results in this paper can provide research basis for the application of friction pendulum isolation device in the field of electrical equipment.

A novel approach for single and combined power quality disturbances detection using fundamental and harmonic phasors estimation model

The growing use of non-linear loads is one of the main reasons for harmonic distortions in distribution systems. Power quality disturbances have caused improper performance of electrical equipment and have created many technical and economic problems for industries and customers. One approach to overcome these problems and also the correct detection of PQ disturbances is power quality monitoring (PQM). Measurement and estimation are two essential tools to understand and investigate PQ problems in distribution networks. Here, a new estimation model is used to simultaneously extract the fundamental and harmonic phasors information of the system. In other words, the proposed estimation model has been used to access system-level data. Also, the recursive variational mode extraction (RVME) approach efficiency has been investigated for detecting power quality disturbances (PQDs). Finally, to validate the effectiveness of the proposed PQDs detection method, six different scenarios of disturbances are investigated. The IEEE 13-bus and IEEE 34-bus standard distribution test networks are used to evaluate the efficiency of the proposed method. Also, the real-time PQ disturbances are used for validating the proposed PQDs detection method. Results obtained demonstrate the efficiency and high accuracy of the proposed approach in correctly diagnosing real-time PQ disturbances.

Distribution Transformer Load Imbalance Analysis at Universitas Bangka Belitung

Loading between phases must always be considered in order to reduce the imbalance, which results in an increase in neutral current and loss of conductor power. Non-linear loads can cause harmonics that affect the increase in copper losses in the transformer. Harmonics can cause distortion of the voltage and current waveforms, so attention must be paid to the specified limits so as not to interfere with the performance of electrical equipment. In addition, these parameters can affect the main electrical parameters, so they must be considered at the specified limits. This study aims to analyze the condition of load imbalance, harmonic content, and the effect on power loss in distribution transformers at Universitas Bangka Belitung. Parameters were measured using a Meterel Power Meter Analyzer type MI 2592 Power Q4 for ten days with the comparative method as a data analysis method. The average current unbalanced percentage is 9.91%, with the highest value at 24.31%. Energy due to power loss in the neutral conductor is 0.46 kWh/10 days, and the total conductor loss is 18.122 kWh/10 days.

Temperature Dependence of Powder Cores Magnetic Properties for Medium-Frequency Applications

Soft magnetic powder cores are attractive because of their loss at medium frequency. However, the performance of electrical equipment is affected by temperature increase by the heat of core losses. In this article, the magnetic properties of nanocrystalline powder core, amorphous powder core, X-Flux (Fe-Si), Sendust (Fe-Si-Al), and ferrite are measured and compared in the range of 25 °C–125 °C from 20 to 100 kHz. The discussed magnetic properties include the temperature-dependent coercive field, initial permeability, inductance factor, saturation flux density, and core loss. The results show that magnetic properties depend on temperature and frequency. In comparison, the nanocrystalline powder core has the best temperature stability and relatively low core loss among the five materials, so it can be well used at broad temperature and medium frequency.

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.

Two-dimensional evaluation model of electrical equipment based on combined weighting and rating algorithm

In the process of electric energy substitution, many industries have gradually replaced the traditional energy consumption equipment with new electrical ones. To avoid the disadvantage of one-sidedness in equipment evaluation and provide a more comprehensive reference for enterprises to replace equipment, a two-dimensional evaluation model composed of static and dynamic rating model is proposed in this paper based on combined weighting and rating algorithm, considering the comprehensive performance in both the inherent properties and the actual power consumption features of electrical equipment. The static and dynamic parameters related are firstly extracted, and then the weights of parameters are determined by the analytic hierarchy process (AHP) subjective weighting algorithm and principal component analysis (PCA) objective weighting algorithm. To compare the performance of different equipment more intuitively, the rank sum ratio (RSR) and technology for order preference by similarity to an ideal solution (TOPSIS) are used to rate the static and dynamic scores, respectively. Case studies for different types of electrical tea dryers in Anji, Zhejiang Province, China, show that the proposed evaluation model is more comprehensive and the rating result is more reasonable, which helps the enterprises have a more comprehensive understanding of the electrical equipment performance.

A Novel Cost-Effective Magnetic Characterization Tool for Soft Magnetic Materials Used in Electrical Machines

Energy losses during the magnetization process of soft magnetic laminations depend on the excitation waveform. Manufacturers of magnetic materials may not provide losses for different excitation waveforms. This may affect the accuracy of the predicted losses which are used to estimate the performance of electrical equipment during the predesign stage. Thus, a characterization tool which is capable of measuring hysteresis loops under controlled magnetization is required. Digital characterization systems available in literature use expensive commercial power amplifiers. In this work, a cost-effective power amplifier circuit is developed and interfaced with a LabVIEW program to characterize soft magnetic materials. The measurements for a sinusoidal excitation from the proposed setup are validated with those from a standard commercial measuring setup. The system is also used to measure hysteresis loops for arbitrary magnetization conditions (magnetic flux density ( B) with harmonics). The proposed setup can operate over a frequency range 35-500 Hz. A small Epstein frame is also designed for measurements at higher frequencies (>200 and <; 500 Hz). A provision is also made to predict three components of dynamic hysteresis losses at any frequency in the above range using the loss separation approach. This capability of the setup enables the user to predict the losses at frequencies beyond the capability of the tool. The predicted losses using this algorithm are validated with measured losses. The proposed setup is cost-effective and can be developed easily using basic electronic components.

Research on metal corrosion mechanism and inhibition measures of transmission and distribution equipment in Hunan

Through the analysis of the different mechanisms of corrosion of metal materials in AC and DC power transmission and transformation equipment and the factors affecting the corrosion rate, the impact of metal corrosion on the mechanical and electrical performance of electrical equipment was deeply studied. The selection of electrical equipment, material inspection and on-site anti-corrosion treatment were proposed. It was an effective measure to prevent corrosion failure of power transmission and transformation equipment.

Simulation analysis of the seismic performance of electrical equipment by redundant length of flexible conductors in interconnected circuits

The interconnection circuit of composite pillar insulators with five different redundant lengths of flexible conductors is established, and the simulation analysis of seismic effects is carried out to study the effect of flexible conductors on the seismic performance of electrical equipment when they are used in the interconnection circuit of electrical equipment. Numerical simulation results are used to analyze the changes in the stress and displacement response of pillar insulators when the redundant length of flexible conductors is varied, and the seismic response law of electrical equipment in the interconnection circuit connected by flexible conductors is obtained, which provides a reference for the seismic design of electrical equipment circuit.

Research on Bending Rigidity at Flange Connections of UHV Composite Electrical Equipment

Pillar electrical equipment is an important part of substations. The application of composite materials in pillar equipment can facilitate the improvement of the seismic performance of electrical equipment. In this paper, the test of elastic modulus and bending rigidity was conducted for individual composite elements in insulators and arresters, and the calculation formula for bending rigidity at the composite flange cementing connections was put forward. The numerical simulation model for the earthquake simulation shaking table test of ±1,100 kV composite pillar insulators was established, in which the bending rigidity value for the flange cementing part was obtained by the test or calculation formula. The numerical simulation results were compared with the earthquake simulation shaking table test results, the dynamic characteristics and seismic response of the model were compared, respectively, the validity of the proposed calculation formula for flange bending rigidity of composite cementing parts was verified, and a convenient and effective means was provided for calculating the seismic performance of composite electrical equipment.

Magnetic Properties Measurement and Analysis of High Frequency Core Materials Considering Temperature Effect

Temperature is a key influence factor of magnetic material properties. It can determine the overall performance of electrical equipment. Accurate measurements of magnetic properties in cores are a prerequisite for loss assessment. In this paper, a testing system for ring sample is designed and constructed to investigate the temperature dependency of magnetic materials, especially at high frequency. Magnetic properties and loss characteristics of the ferrite (N87), nanocrystalline (1k107B) and amorphous alloys (1k101) are measured and analyzed in the range of 25 °C to 120 °C from 1 kHz to 20 kHz. The temperature dependency of three materials at different conditions is systematically compared by using the coefficient of loss variation (CLV). The comprehensive performance of core materials is discussed in combination with the experimental phenomena and results.

Isolation design for slender ultra-high–voltage composite equipment using modal parameters considering multiple responses

Isolation can effectively improve the seismic performance of electrical equipment in substations. Rotational base isolation is a normal solution for the seismic improvement of low-voltage porcelain equipment, because stress is typically the key concern. However, for ultra high voltage (UHV) composite equipment, which is slender and sensitive to high-order modes, displacement, sometimes together with acceleration, should also be considered during isolation design. Therefore, three candidate types of isolation – rotational base isolation, horizontal base isolation and middle isolation – are compared and optimised specifically for slender composite post equipment to investigate the effectiveness of different types of isolation for different targets. As detailed finite element (FE) analysis is time-consuming, a method in which the equipment is replaced by modal parameters and decoupled from the isolation is proposed to optimise the isolation under the recommended artificial input in code. The optimal design of the isolation is achieved by setting a threshold for multiple responses using exhaustive search or particle swarm optimisation (PSO) methods. The parametric study shows that the additional viscous damper is not always advantageous to response mitigation. As alternatives to rotational base isolation, horizontal and middle isolation can also result in significant response mitigation. In particular, horizontal isolation is advantageous in acceleration mitigation, whereas middle isolation is suitable for equipment with heavy supports. The effectiveness of the proposed isolation is validated by 20 modulated seismic inputs, and the correctness of the equivalent model is validated by detailed FE analyses. The proposed equivalent model, which has distinct advantages in terms of saving time, and three choices of isolation are recommended in optimal design for seismic improvement for UHV equipment that has strict air clearance requirements or contains precise electronic units vulnerable to acceleration.

The Application of Electrical Automation in Electrical Engineering

To apply automation in electrical engineering is to use a series of devices with functions of automatic detection and control to realize the real-time or remote control, management, and monitoring of the original electrical system. Therefore, the electrical automation technology has broad development space in the construction of electrical engineering, and it is worth of application and study for relevant electrical installation engineering and scientific research departments. In the actual production process, it is necessary to optimize the production mode, reduce the cost, and keep the good working performance of electrical equipment. Based on this, this article briefly analyzes the application of electrical automation in electrical engineering, hoping to provide an effective reference.

Optimization of heating characteristics of gas insulated switch-gear (GIS)

Protection types of equipment are the mainstay of a power system. Recently, gas insulated metal-enclosed switch-gear (GIS) has developed the most important part of a power system protection. High-pressure gas insulated metal-enclosed switchgear may suffer overheating and can cause fatal accidents. The miniaturization and high performance of electrical equipment highlight the importance of thermal analysis. In this paper, the model simplification method of gas insulated metal-enclosed switchgear is studied and the complex structure of GIS is simplified according to the heat source of GIS. The heat source of GIS includes Joule heat of conductor and contact resistance heating. Furthermore, this paper considers the cooling effect of natural convection SF6. By employing the method of AC electromagnetic analysis and fluid-solid coupling analysis, harmonics under the effect of eddy current losses and the contact resistance method for the convection heat dissipation (for shell and air) have been selected. Finally, obtain the temperature distribution of gas insulated metal-enclosed switchgear. The simulation results are verified by temperature rise test. Thermal simulation analysis of gas insulated metal-enclosed switchgear is carried out, which can provide a theoretical and experimental reference for further research and design of improved protected products.

Experimental research on sealing performance of sulfur hexafluoride electrical equipment under low-temperature environment

It is discovered that the sealing performance of the sulfur hexafluoride electrical equipment worsens under low temperature, but research in the aspect is reported rarely when corresponding measures are adopted for improving the sealing performance of electrical equipment. Therefore, sealing and leakage test of sulfur hexafluoride electrical equipment was implemented under low-temperature environment according to the analysis on gas sealing methods of sulfur hexafluoride electrical equipment. Causes of gas leakage of sulfur hexafluoride electrical equipment under low temperature environment were analyzed according to test results. Effective measures were proposed for improving the gas sealing performance of the equipment, thereby providing valuable reference for gas sealing design, installation, operation maintenance and failure analysis of sulfur hexafluoride electrical equipment under low - temperature environment.

Corona Identification of Impulse Voltage and Current

The corona effect in the power system has a dominant role in reducing the efficiency of the high-voltage lines. In this study, the current and voltage impulses, which are important in corona determination, have been examined in frequecy spectrogram base from test result. The frequency spectrogram graphs have been obtained from the current-time and voltage-time variation by Matlab program. With these graphs, frequency values have been found to provide an important clarification of the insulation performance of electrical equipment for reliable and accurate diagnosis. These values have been observed according to different conditions like pressure, polarity, and insulation ambient. This spectrogram analysis can be used to find the characteristic frequencies and eliminate the disturbance effect. The time between corona steps decrease when Sulphur hexafluoride (SF6) gas pressure is increased. The time of second corona is close to leader's discharge time. Corona starts early when SF6 amount is decreased in gas mixtures. The corona currents are large in the low SF6 gas mixtures, this situation is related to the high insulation of the SF6 gas. A feature which is dependent the frequency is not found.