Electric Power Equipment Research Articles

INVESTIGATION OF THE INFLUENCE OF THE TRANSFORMER OF A SERIES ACTIVE FILTER ON THE QUALITY OF VOLTAGE

Purpose. Investigate the features of using a series power transformer for the implementation of longitudinal compensation. Methodology. Methods of solving systems of differential equations of the first order, methods of matrix transformations, methods of numerical simulation, methods of calculating the active part of Frieze power, methods of the theory of transformation of coordinate systems. Findings. The functional scheme of the successive power active filter is realized in the implementation of longitudinal compensation, the connection of the parameters of the transformer with the parameters of the mode is investigated, the processes that take place in the transformer are considered, a method for determining the signal of the control of the successive filter is developed, in the visual programming environment a model of the simplified system of electricity consumption has been developed, researches, on the basis of which analysis, the efficiency of application of the proposed solution according to the level of voltage on the invoice is shown ancestry A series of experiments with a change in the active load power was carried out to assess the impact of the transformer on the load voltage. The conclusions of the influence of the parameters of the active filter transformers on the load voltage are formulated. Originality. Non-compliance with the quality of energy indicators leads to economic losses, reduced reliability of operation of electric networks and violation of technological processes, increase of additional losses in networks and elements of electrical equipment, shortening of service life of electrical power equipment of power systems. Longitudinal compensation is one of the solutions for ensuring the quality of electricity. Compensation provides for increasing the dynamic stability of the transmission line and the stability of the main network voltage. On the basis of the analysis of known works, it has been established that passive compensators with a permanent structure are less satisfied with the requirements for maintaining the quality of electricity. As a result, controlled filter compensating devices are developed and implemented - power active filters. The principle of the compensator - constantly creates harmonic voltages that exactly match the harmonic components generated by the load. The distortion is already compensated, already present in the power supply system. As a result, the voltage remains sinusoidal. The compensatory properties of the active filter depend on the algorithm for determining the control signal. With the use of the Frize power theory, a cer tain sequence of the synthesis of a control signal by a series active active filter is proposed. Practical value. A certain sequence of synthesizing the control signal of the compensator has been created, the effect of the power active filter transformers has been investigated for the realization of longitudinal compensation.

Analysis of Electric Field and Current Density for Different Electrode Configuration of XLPE Insulation

The most important aspect influencing the circumstance and characteristics of electrical discharges is the distribution of electric field in the gap of electrodes. The study of discharge performance requires details on the variation of maximum electric field around the electrode. In electrical power system, the insulation of high voltage power system usually subjected with high electric field. The high electric field causes the degradation performance of insulation and electrical breakdown start to occur. Generally, the standard sphere gaps widely used for protective device in electrical power equipment. This project is study about the electric field distribution and current density for different electrode configuration with XLPE barrier. Hence, the different electrode configuration influences the electric field distribution. This project mainly involves the simulation in order to evaluate the maximum electric field for different electrode configuration. Finite Element Method (FEM) software has been used in this project to perform the simulation. This project also discusses the breakdown characteristics of the XLPE. The accurate evaluation of electric field distribution and maximum electric field is an essential for the determination of discharge behavior of high voltage apparatus and components. The degree of uniformity is very low for pointed rod-plane when compared to other two electrode configurations. The non- uniform electric distribution creates electrical stress within the surface of dielectric barrier. As a conclusion, when the gap distance between the electrodes increase the electric field decrease.

Infrastructure for Integration of Legacy Electrical Equipment into a Smart-Grid Using Wireless Sensor Networks.

At present, the standardisation of electrical equipment communications is on the rise. In particular, manufacturers are releasing equipment for the smart grid endowed with communication protocols such as DNP3, IEC 61850, and MODBUS. However, there are legacy equipment operating in the electricity distribution network that cannot communicate using any of these protocols. Thus, we propose an infrastructure to allow the integration of legacy electrical equipment to smart grids by using wireless sensor networks (WSNs). In this infrastructure, each legacy electrical device is connected to a sensor node, and the sink node runs a middleware that enables the integration of this device into a smart grid based on suitable communication protocols. This middleware performs tasks such as the translation of messages between the power substation control centre (PSCC) and electrical equipment in the smart grid. Moreover, the infrastructure satisfies certain requirements for communication between the electrical equipment and the PSCC, such as enhanced security, short response time, and automatic configuration. The paper’s contributions include a solution that enables electrical companies to integrate their legacy equipment into smart-grid networks relying on any of the above mentioned communication protocols. This integration will reduce the costs related to the modernisation of power substations.

СПОСОБ ПОВЫШЕНИЯ КПД ЭЛЕКТРОЛИЗНЫХ УСТАНОВОК В ГРУППОВОМ ВОДОПРОВОДЕ ЛИМАНСКОГО РАЙОНА ПУТЕМ ПРИМЕНЕНИЯ ВОДОРОДНЫХ ТЕХНОЛОГИЙ

One of the main units in the water supply network of MUC "Liman water pipelines" is a water purification plant. Analysis of the water purification plant operation in Olya village revealed problems of imperfect use of electrolysis and overall nonrational application of power resources and electric equipment for water purification. There have been found main areas of concern in the plant of sodium hypochlorite production. There has been proposed the method for increasing efficiency of the station and reducing energy costs, as well as for increasing service life of the equipment. This method is based on the use of hydrogen as a fuel for heating the electrolyte before it enters the galvanic bath.

The Main Stages of Development of an Electric Drive of a Cold Rolling Mill

This article discusses selection of variables of electrical power equipment and variables of adjusting feedbacks of a control system of heavy-duty equipment using sequential partial optimization. The stages of the proposed procedure as well as its evaluation are exemplified by electric drive of cold rolling mill. It has been demonstrated that the best effect is achieved at the second stage due to application of elongated motor; herewith, it is possible to decrease inertia by about two times and the total transient time by about 25–30%. Practical design methods of electrical-power equipment of high precision drives can be supplemented by certain stages. This is very important for equipment operating in wide range of loads on the working shaft (more than four to five rated values) and/or that contains elements with mechanical compliance in control channel. By means of appropriate selection of the reduction ratio, it is possible to decrease significantly the influence of resonant maximums, which is necessary if the mechanical part is to meet requirements for quality of adjustment of a sequential correcting device of a conventional subordinate process-control circuit of a metallurgical electric device. The proposed procedure can be successfully applied also in systems with conventional variables for mechanisms operating with frequent starts/brakes. For instance, getting rid of ratios of rotor length to its diameter that are conventional for an asynchronous motor in some cases permits losses to be approximately halved.

TO THE PROBLEM OF HIGH-VOLTAGE EQUIPMENT NOISE DIAGNOSTICS

Application possibilities of electrical power equipment noise diagnostics are shown. The diagnostics possesses increased depth and the enlarged reliability of diagnosing. Main guidelines of the technique based on determination of external and internal constructive elements deficiencies are described. Stages of obtaining information about full deficiency of the equipment are explained in detail on the example of diagnosing of five power autotransformers with various term of operation. The received results well correspond with the data obtained by other diagnostic methods.

The study of operating an air conditioning system using Maisotsenko-Cycle

The project aims to design and build an air conditioning system that runs on the Maisotsenko cycle. The system is required to condition and cool down ambient air for a small residential space with the reduction in the use of electricity and eliminating the use of commercial refrigerants. This project can operate at its optimum performance in remote areas like oil diggers and other projects that run in the desert or any site that would not have a very high relative humidity level. The Maisotsenko cycle is known as the thermodynamic concept that captures energy from the air by using the psychometric renewable energy available in the latent heat in water evaporating in air. The heat and mass exchanger design was based on choosing a material that would-be water resistant and breathable, which was found to be layers of cardboard placed on top of each other and thus creating channels for air to pass through. Aiming for this design eliminates any high power electrical equipment such as compressors, condensers and evaporators that would be used in an AC system with the exception of a 600 W blower and a 10 W fan, thus making it a more environmentally friendly project. Moreover, the project is limited by the ambient temperature and humidity, as the model operates at an optimum when the relative humidity is lower.

A new vibration analysis approach for transformer fault prognosis over cloud environment

Internet of Things (IoT) and its applications are becoming more prevalent among researchers and companies across the world. IoT technologies offer solutions to many industrial challenges and, as such, they replace classical diagnostic methods with prognostic techniques that can potentially lead to smart monitoring systems. One of the vital applications of IoT is in smart monitoring of major electric power equipment such as transformers whilst in service. Mechanical integrity and operation condition of energized transformers might be evaluated by employing vibration method, which is a non-destructive and economic approach. However, researchers have not yet reached a consensus on how to interpret the results of this method. A new approach has been introduced in this study in order to evaluate transformer real-time vibration signal. A detailed discussion has been provided on transformer vibration modelling and interpretation challenges of the results. Furthermore, a novel method is introduced to evaluate transformer vibration signal during short circuit contingency. As we show, it is straightforward to implement the introduced methods over the cloud environment. Practical studies are conducted on two distribution transformers to examine the introduced methods. The results demonstrate that the methods are remarkably effective, fast and feasible to be programmed over cloud for transformer short circuit fault prognosis.

Seismic Analysis of a 500-kV Power Transformer of the Type Damaged in the 2008 Wenchuan Earthquake

AbstractAs indispensable electric power equipment in substations, high-voltage power transformers have experienced severe damage in past earthquakes. This paper illustrates an earthquake-damaged 50...

Assessment of Eco-friendly Gases for Electrical Insulation to Replace the Most Potent Industrial Greenhouse Gas SF6.

Gases for electrical insulation are essential for the operation of electric power equipment. This Review gives a brief history of gaseous insulation that involved the emergence of the most potent industrial greenhouse gas known today, namely sulfur hexafluoride. SF6 paved the way to space-saving equipment for the transmission and distribution of electrical energy. Its ever-rising usage in the electrical grid also played a decisive role in the continuous increase of atmospheric SF6 abundance over the last decades. This Review broadly covers the environmental concerns related to SF6 emissions and assesses the latest generation of eco-friendly replacement gases. They offer great potential for reducing greenhouse gas emissions from electrical equipment but at the same time involve technical trade-offs. The rumors of one or the other being superior seem premature, in particular because of the lack of dielectric, environmental, and chemical information for these relatively novel compounds and their dissociation products during operation.

Advanced methods of transportation and distribution of electrical power in smart power grids of railways

The relevance of the work is determined by the need to improve the electrical distribution grids of railways on the basis of digital technologies. The article presents advanced methods of transportation and distribution of electric power in smart power grids of railways based on multi-agent control. The analysis of the power supply system for stationary railroad consumers was performed and advanced ways of their development were defined. These methods should provide increased speed, adaptive determination of restrictions on using electric power equipment, management of mode parameters, sectioning and power flow modes in electrical distribution grids, restoration of power supply after emergency events. The method of adaptive control of transportation and distribution of electric energy in the power supply system of stationary railway consumers is developed based on the hierarchical structure of IEC 61850. This method takes into account the coordination of managing and local controllers in the data exchange environment, the control results and the variable area of responsibility of controllers and their division according to their functional purpose based on the multi-agent approach. The method of power flow control was developed to reduce power losses, increase the capacity of transport channels and ensure the restoration of the normal mode of the electric network by reconfiguring it and controlling active elements based on graph theory. The method takes into account the expected daily load curve, limits on the demand for capacity by active consumers and the possibility of a closed mode of electrical network operation through controlled cross-sections. The simulation results presented on the test circuit have showed the feasibility and efficiency of the proposed approaches.

Associated Graetz-Nusselt Problems with Thermal Sources in Thermally Thin Channel Wa

The analytical solutions to conjugated problems of convective heat transfer in plane and cylindrical channels that are widely used in cooling systems of various electrotechnical and electrical power equipment are presented. A fundamental difference in thermal calculations between the proposed and the classical approach, where the heat transfer coefficient is used, lies in the direct determination of maximum temperature. The problem was solved through the method of variable separation. One of the most important results is that the same integro-differential equation with different eigenvalues has been obtained for the temperature in thermally thin walls of both flat and cylindrical cooling channels. The equation was solved using small parameter method. The dependence of temperature of the cooling channel walls from thermophysical properties and geometrical parameters of the heat-producing walls has been shown. The presented examples of calculations allow making a very important conclusion: there is a defining dependence of maximum and average temperatures of the heat-producing walls of cooling channels from the thermal conductivity of a solid wall. Selecting one of the models of the flow in the channel can serve as a two-way assessment of temperature in engineering design.

Study on Prediction of Rack Temperature in Server Room Using Machine Learning

In recent years, data centers (DC) have become increasingly important. Accordingly, highly efficient and reliable operation and management of DCs have been required. The conventional layout design of racks and ICT equipment in a server room considers the current space and current capacity of power and cooling status, but it does not take into account the temperature or energy performance after environmental changes such as rack removals or additions. On the other hand, for temperature management in the server room, the DC users usually requires DC operator to comply with a service level agreement (SLA) that stipulates that the rack intake temperature is to be kept below a certain level. However, it is not possible to know temperature after environmental changes. To address this problem, we have constructed some models to predict rack intake air temperatures in a server room by using information of ICT equipment, electric power equipment, and air conditioning equipment. In this paper, we propose a method of predicting the temperature after environment changes by using machine learning are developed, and the results of verification and effectiveness in the verification room are reported.

Mode and climatic factors effect on energy losses in transient heat modes of transmission lines

Electrical energy losses increase in modern grids. The losses are connected with an increase in consumption. Existing models of electric power losses estimation considering climatic factors do not allow estimating the cable temperature in real time. Considering weather and mode factors in real time allows to meet effectively and safely the consumer’s needs to minimize energy losses during transmission, to use electric power equipment effectively. These factors increase an interest in the evaluation of the dynamic thermal mode of overhead transmission lines conductors. The article discusses an approximate analytic solution of the heat balance equation in the transient operation mode of overhead lines based on the least squares method. The accuracy of the results obtained is comparable with the results of solving the heat balance equation of transient thermal mode with the Runge-Kutt method. The analysis of mode and climatic factors effect on the cable temperature in a dynamic thermal mode is presented. The calculation of the maximum permissible current for variation of weather conditions is made. The average electric energy losses during the transient process are calculated with the change of wind, air temperature and solar radiation. The parameters having the greatest effect on the transmission capacity are identified.

Speech Enhancement Based on NMF Under Electric Vehicle Noise Condition

Speech-based human–machine interaction (HMI) is essential to electronic navigation, autonomous cars, and intelligent vehicles. The noises generated by the mechanical motion or electric power equipment degrade speech quality and result in HMI failing to work effectively. However, there is relatively little literature available on speech enhancement under electric vehicle noise condition. This paper presents a speech enhancement method based on improved nonnegative matrix factorization (ImNMF). Unlike the traditional nonnegative matrix factorization (NMF) trains its speech dictionary using speech recorded in advance which inevitably contains a little noise component, ImNMF generates the speech dictionary using the spectra of pitch and their harmonics via mathematical model. This purpose is to guarantee the purity of speech dictionary. In addition, in order to alleviate the loss of the information of the noise sample, ImNMF constructs noise dictionary by a combination of the gain adjusted spectrum frames of the noise samples separated online. Compared with traditional NMF, the ImNMF noise atoms are relatively larger. Thus, the representation of speech signal mixed with noise atoms is greatly reduced. Therefore, ImNMF can reduce distortion of reconstructed speech while enhancing the recovered speech quality. Speech enhancement and speaker verification experiments on NUST603 and TIMIT data showed that the proposed ImNMF can effectively enhance speech signal in the noise environment of electric vehicles and further can reduce the equal error rate of the speaker verification system.

Assessment of Eco-friendly Gases for Electrical Insulation to Replace the Most Potent Industrial Greenhouse Gas SF6

Gases for electrical insulation are essential for the operation of electric power equipment. This Review gives a brief history of gaseous insulation that involved the emergence of the most potent industrial greenhouse gas known today, namely sulfur hexafluoride. SF6 paved the way to space-saving equipment for the transmission and distribution of electrical energy. Its ever-rising usage in the electrical grid also played a decisive role in the continuous increase of atmospheric SF6 abundance over the last decades. This Review broadly covers the environmental concerns related to SF6 emissions and assesses the latest generation of eco-friendly replacement gases. They offer great potential for reducing greenhouse gas emissions from electrical equipment but at the same time involve technical trade-offs. The rumors of one or the other being superior seem premature, in particular because of the lack of dielectric, environmental, and chemical information for these relatively novel compounds and their dissociation...

Predictive Maintenance of Power Substation Equipment by Infrared Thermography Using a Machine-Learning Approach

A variety of reasons, specifically contact issues, irregular loads, cracks in insulation, defective relays, terminal junctions and other similar issues, increase the internal temperature of electrical instruments. This results in unexpected disturbances and potential damage to power equipment. Therefore, the initial prevention measures of thermal anomalies in electrical tools are essential to prevent power-equipment failure. In this article, we address this initial prevention mechanism for power substations using a computer-vision approach by taking advantage of infrared thermal images. The thermal images are taken through infrared cameras without disturbing the working operations of power substations. Thus, this article augments the non-destructive approach to defect analysis in electrical power equipment using computer vision and machine learning. We use a total of 150 thermal pictures of different electrical equipment in 10 different substations in operating conditions, using 300 different hotspots. Our approach uses multi-layered perceptron (MLP) to classify the thermal conditions of components of power substations into “defect” and “non-defect” classes. A total of eleven features, which are first-order and second-order statistical features, are calculated from the thermal sample images. The performance of MLP shows initial accuracy of 79.78%. We further augment the MLP with graph cut to increase accuracy to 84%. We argue that with the successful development and deployment of this new system, the Technology Department of Chongqing can arrange the recommended actions and thus save cost in repair and outages. This can play an important role in the quick and reliable inspection to potentially prevent power substation equipment from failure, which will save the whole system from breakdown. The increased 84% accuracy with the integration of the graph cut shows the efficacy of the proposed defect analysis approach.

Modeling and experimental study of a linear power generator for road energy harvesting

There are a large number of vehicles running on the road, and the shape of the road surface varies accordingly. Thus, this kinetic energy can be harvested to power electrical equipment along the road, and this energy harvesting technology has good environmental adaptability because it will not be affected by the sun, wind, or other natural environmental factors. A permanent magnet linear generator is designed and tested for road kinetic energy harvesting. The generator is described by a single degree of freedom system model with mass-spring-damping. The system response is analysed on the basis of the system model. The mover's vibration response is modeled over two stages according to the vehicle's wheel load. The power generation process is simulated and calculated according to the aforementioned models. The magnetic force and magnetic field are calculated by use of the finite element method; because of the non-linear magnetic force, the output electromotive force (EMF) is subject to frequency multiplication under conditions of sinusoidal displacement input. A prototype is manufactured and embedded in the road for experimental research purposes. The test result shows that the maximum peak-to-peak value of the output EMF and average power are up to 484.18 V and 255.1 W, respectively, as a car passes over the generator at a speed 20 km/h. Moreover, the time-domain and amplitude-frequency characteristics agree well with those calculated. It is demonstrated that the proposed model is able to describe the road power generator.

Harmonics analysis of the ITER poloidal field converter based on a piecewise method

Poloidal field (PF) converters provide controlled DC voltage and current to PF coils. The many harmonics generated by the PF converter flow into the power grid and seriously affect power systems and electric equipment. Due to the complexity of the system, the traditional integral operation in Fourier analysis is complicated and inaccurate. This paper presents a piecewise method to calculate the harmonics of the ITER PF converter. The relationship between the grid input current and the DC output current of the ITER PF converter is deduced. The grid current is decomposed into the sum of some simple functions. By calculating simple function harmonics based on the piecewise method, the harmonics of the PF converter under different operation modes are obtained. In order to examine the validity of the method, a simulation model is established based on Matlab/Simulink and a relevant experiment is implemented in the ITER PF integration test platform. Comparative results are given. The calculated results are found to be consistent with simulation and experiment. The piecewise method is proved correct and valid for calculating the system harmonics.

A review of power quality issues in electrified rails

Electrified railways are among of the largest consumers of electric energy with longitudinally distributed power supply stations and connected to lines fixed (unmovable) electrical loads (consumers) and moving loads (vehicles), which operate, in general case, in nonlinear pulse modes. Due to the electrical non-linear nature of power stations and loads, current and voltage distortions appear in railway lines that devastating impact on the entire power system and consumers. The development of high-speed railways and the use of new types of rolling stock with power electrical equipment and pulse-width modulation of the traction current lead to problems with electromagnetic compatibility (EMC) and power quality in feeding grids that can adversely influence on train movement safety.The purpose of this article is to give a brief overview of power quality issues in electrified railways and also to consider related PQ standards. The main power quality disturbances are illustrated by using fragments of the traction current and voltage time-dependences measured during tests of the rolling stocks on electromagnetic compatibility with rail circuits.The traction current and voltage were registered in vehicle power equipment circuits, using a current and voltage probes whose signals were converted by analog-to-digital converter and recorded by PC.The different definitions of power quality presented in standards and literature are discussed.The main power quality disturbances were illustrated using specially chosen characteristic fragments of registered traction current, and some their parameters and electrical processes caused them are considered.