Power Losses In Transformers Research Articles

Analysis of Power Loss in Forward Converter Transformer Using a Novel Machine Learning Based Optimization Framework

High power and high voltage gains in Forward Converter significance are a foremost topic for wind power switch mode supplies. However, due to the recent penetration of forward converter usage in the power network and wide range of load, the reliability and power loss problem becomes a crucial one. Therefore, this paper projected a novel Grey Wolf based Boosting Intelligent Frame (GWbBIF) control algorithm for improving the reliability of power system since the incorporation of forward converter to the entire system level. Consequently, the power loss of transformer is optimized by the projected Grey Wolf fitness function. The implementation of this work has been done on MATLAB/Simulink. The simulation outcomes of the proposed system show that the forward converter reliability and power loss of transformer are considered as significant aspects while estimating the whole system function. The proposed outcomes are compared with the conventional methods for validating the importance of the projected method.

Influence of the load of the power transformer on the magnetizing current

Data on the magnetizing current of power transformers are taken from the experience of idling. It is considered that it does not change under load. The experience of idling does not take into account the uneven saturation of the magnetic core when working under load. The hypothesis of a significant error caused by this assumption is put forward. The experiments carried out confirmed the hypothesis. The differences in the measurement of the magnetizing current at idle and under load in the experiments reached 28-32%. This determines the inaccuracy in the calculations of currents and losses in power transformers, which, taking into account the continuous operation of transformers and their large number, can be significant. It is proposed to add the experience of working at rated load when testing power transformers. This experience will not only allow us to clarify the val-ue of the magnetizing current under load and magnetic losses, but also to re-fine the design of the transformer in the direction of reducing the magnetizing current by eliminating uneven saturation of the magnetic circuit when working under load, due to the influence of magnetic scattering fields. This is possible by locally increasing the cross-section of the magnetic circuit in the busiest places of the magnetic circuit.

Analysis of loss on single-phase dry transformers with non-linear load

The paper studies power losses in transformers due to non-linear loads. The research aims to analyze the power loss in a single-phase dry transformer under a non-linear load. The research uses an SW43W Power supply type, FlukeView Power Quality Analyzer as a DC or AC power supply on the primary side of the transformer. The non-linear load is connected to the secondary side. The loading test of the dry transformer was carried out at non-linear loads. The load variations used 0 %; 12.5 %; 25 %; 37.5 %; 50 %; 62.5 %; 75 %; 87.5 % and 100 %, as well as variations in the THD value by adjusting the ignition angle (α). The non-linear loads used are Half-Wave Rectifier and Controlled Half-Wave Rectifier with resistive loads with variations in THD values. The results showed that the transformer losses comprised Pno load and Pload. The operation of the transformer with constant input voltage and frequency with THDv<5 % resulted in a constant Pno load value at all load values. The greater the percentage of the load, the higher the load. The increase in THD because of non-linear load will increase the load on the transformer. The value of the derating factor is obtained by connecting the increase in losses (∆PLosses), which is influenced by THD and the increase in temperature T(°C) in dry transformers. When the transformer is loaded with a non-linear load, the derating factor<1. THD and derating factor form a linear relationship, when THD increases, the derating factor value decreases. Linear load on the transformer causes a decrease in its capacity, but if it gets a non-linear load with THD=39.1 %, it can withstand a load of 84.294 %, besides the increase in total harmonic distortion will increase losses and reduce transformer capacity

Electric Vehicles Charging Management Using Machine Learning Considering Fast Charging and Vehicle-to-Grid Operation

Electric vehicles (EVs) have gained in popularity over the years. The charging of a high number of EVs harms the distribution system. As a result, increased transformer overloads, power losses, and voltage fluctuations may occur. Thus, management of EVs is required to address these challenges. An EV charging management system based on machine learning (ML) is utilized to route EVs to charging stations to minimize the load variance, power losses, voltage fluctuations, and charging cost whilst considering conventional charging, fast charging, and vehicle-to-grid (V2G) technologies. A number of ML algorithms are contrasted in terms of their performances in optimization since ML has the ability to create accurate future decisions based on historical data, which are Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbours (KNN), Long Short-Term Memory (LSTM) and Deep Neural Networks (DNN). The results verify the reliability of the use of LSTM for the management of EVs to ensure high accuracy. The LSTM model successfully minimizes power losses and voltage fluctuations and achieves peak shaving by flattening the load curve. Furthermore, the charging cost is minimized. Additionally, the efficiency of the management system proved to be robust against the uncertainty of the load data that is used as an input to the ML system.

Electrical power systems energy saving and consumption reduction through transformer capacity and operation scheme

on the basis of summarizing the power loss of transformer, based on the optimal load rate of transformer or the principle of minimum comprehensive energy efficiency cost[1], the transformer capacity can be reasonably selected, so as to effectively reduce the increase of operation cost caused by too large or too small transformer capacity selection, and improve the energy saving and economy; After the transformer is selected, the economic operation scheme of the transformer can be used to arrange the operation[2], including making the transformer work in the economic operation section, economic switching among various operation modes of the transformer, economic distribution among transformer loads, etc.

A new parallel and decomposition approach to solve the medium- and low-voltage planning of large-scale power distribution systems

The world energy demand is increasing. Currently, most electricity generation sources are fossil fuels. In recent years, the global energy matrix for power generation is changing, in order to meet the demand with minimal environmental impacts. In this context, a new approach to solve the medium- (MV) and low- voltage (LV) planning of large-scale distribution systems via parallel computing and decomposition techniques is proposed. The mathematical formulation considers the allocation of substations, distribution transformers, MV and LV circuits, support structures, poles, renewable energy sources (RES), and energy storage sources (ESS). In addition, variable costs related to the operation of RES and ESS, power losses in cables, distribution transformers and substations, energy purchased from substations, and greenhouse gas emissions are also taken into account. System reliability and maintenance costs of these devices are also considered in the planning. To evaluate the new methodology performance, tests in a large-scale distribution system with 200 nodes in MV and 1672 nodes in LV is considered. Numerical results show the proposed methodology is able to find good solutions that guarantee the minimization of planning costs considering RES and ESS allocation. Furthermore, system reliability is improved by up to 22% and greenhouse gas emissions mitigation by up to 18%.

Study of power transformer loading in rural power supply systems

The purpose of this study is to study the effect of loading power transformers (PT) in their continuous use on their energy efficiency on a real-life example of existing rural electric networks. It is noted that the vast majority of PT in rural areas have a very low load factor, which leads to an increase in specific losses of electric energy when this is transmitted to various consumers. It is planned to optimize the existing synchronized power supply systems in rural areas by creating new power supply projects in such a way as to integrate existing power sources and ensure the most efficient loading of power transformers for the subsequent transfer of these systems to isolated ones that receive power from distributed generation facilities. As an example, we use data from an electric grid company on loading power transformers in one of the districts of the Irkutsk region. Issues related to the determination of electric energy losses in rural PT at different numerical values of their load factors are considered. A computing device was developed using modern programming tools in the MATLAB system, which has been used to calculate and plot the dependence of power losses in transformers of various capacities on the actual and recommended load factors, as well as the dependence of specific losses during the transit of 1 kVA of power through a power transformer at the actual, recommended and optimal load factors. The analysis of specific losses of electric energy at the actual, recommended and optimal load factors of PT is made. Based on the analysis, the intervals of optimal load factors for different rated power of PT of rural distribution electric networks are proposed. It is noted that to increase the energy efficiency of PT, it is necessary to reduce idling losses by increasing the load of these transformers, which can be achieved by reducing the number of transformers while changing the configuration of 0.38 kV distribution networks.

Large- and Small-Signal Average-Value Modeling of Dual-Active-Bridge DC–DC Converter With Triple-Phase-Shift Control

This article presents a novel reduced order average model for dual-active-bridge converter which can be applied to all modulation methods, such as single-phase-shift modulation, dual-phase-shift modulation, extended-phase-shift modulation and triple-phase-shift modulation. This model considers conduction, inductance, and transformer power losses. Furthermore, the input-output filters are suitable for system performance analysis. Based on the large-signal average model, the small-signal model and the output transfer function are derived. The detailed model for predicting the large-signal transient is established and the small signal analysis in frequency domain is carried out. This model can accurately predict the steady-state and transient-state response of the system. The experimental results agreed well with the simulation results which proved the accuracy and correctness of the model.

ПОВЫШЕНИЕ ЭНЕРГЕТИЧЕСКОЙ ЭФФЕКТИВНОСТИ СИСТЕМЫ ТЯГОВОГО ЭЛЕКТРОСНАБЖЕНИЯ ЗА СЧЕТ ПРИМЕНЕНИЯ УСТРОЙСТВ РЕГУЛИРОВАНИЯ НАПРЯЖЕНИЯ

Increase of energy efficiency of a traction power supply system in condition of growth of goods turnover becomes a very actual task. The paper considers energy efficiency of both the existing traction power supply system without current regulating devices and the traction power supply system with the use of such devices. The author has determined the influence of increase of speed from 50 to 100 km/h on power consumption on traction including on power consumption according counters of electric locomotives and losses of power in the catenary. Also as a variant of strengthening the paper considers a buffer traction power supply system consisting of main regulated traction substations and a not regulated single-unit traction substation in the middle of inter-substation zone. This system is used in situation when regulation of voltage on main traction substations doesn’t provide the increase of traffic and carrier capacity of sections (directions). Modeling of operation of the traction power supply system has been carried out on a section of the Sverdlovsk Railway. All the calculations have been executed for the batch of freight trains with the mass of 7100 tons. In calculations the author has applied a new clarifying method that includes the use of corrective current coefficients and the assessment of voltage level on an electric locomotive current collector. The energy efficiency of the traction power supply system has been assessed by such indicators as a level of voltage on the electric locomotive current collector, power losses in catenary and transformers of traction substations.

Analysis of Losses in Cables and Transformers with Unbalanced Load and Current Harmonics

The power quality problems are more and more serious in the power system. The harmonics and the three-phase imbalance have a greater impact on the line loss of power grid. We focus on the power losses in cables and transformers with unbalanced load in current harmonics basing on the equivalent resistance method. The impact caused by the skin effect is illustrated in order to enhance the accuracy of the theoretical calculation. For this purpose, a mathematical development that takes in account the presence of current harmonic components and unbalanced load in the losses calculation is presented. The reliability of the method is verified in a simulation model. According to the comparative analysis between the simulation and the proposed method, we can conclude that the harmonic resistance calculation method considering skin effect is more accurate than the traditional method. The results show that the additional loss caused by the harmonics has a nonlinear relation with the harmonic currents. At the same time, the additional loss of distribution network under compound disturbance with unbalanced load in current harmonics is studied. Compared with the cases that two phase load are heavy and one phase load is light or one phase load is heavy and other two phase load are light, when one phase load is heavy, one phase load is light and one phase load is the average value of the others, the additional loss of the system is the least one. The additional loss for the case with that two phase load are heavy and one phase load is light is the biggest one.

Study on Driving Method to Reduce Power Loss of Transformer Mounted on Large Current Generator

Study on Driving Method to Reduce Power Loss of Transformer Mounted on Large Current Generator

Geomagnetic induced current modelling and analysis on high voltage power system

Geomagnetically induced current (GIC) has become a significant concern that can affect the electrical power grid by causing a half-cycle saturation of power transformers. This saturation leads to an increase in even and odd harmonic distortions and reactive power losses of transformers, which may consequence in improperly triggering relays, tripping reactive power (VAR) compensators and shunt capacitor banks. Also, these reactive losses, harmonic, and the stray flux resulted due to this saturation may lead to overheating windings and cores of power transformers and generators and hence blackout. In this paper, GIC analysis has been conducted on a modified IEEE-18 bus test system by using Power System Simulator for Engineering (PSS/E) and Power System Computer-Aided (PSCAD/EMTDC) software. The simulation results have been obtained by considering a worst-case scenario of geomagnetic disturbance (GMD) by applying uniform induced electric fields with values of 10 V/km and 20 V/km at different directions with and without GIC blocking devices. Also, the impact of grounding resistances of the substations on calculated GIC due same mentioned induced fields has been investigated. The results show that the highest total reactive power losses across the system are obtained due to related induced electric fields at 120° and 300° storm angle. After the connection of GIC blocking devices to the substations, these reactive losses have drastically reduced. In addition, simulation results of the same test system by using PSCAD platform are obtained to investigate hysteresis and harmonic results during system operation and the presence of GIC.

Improvement of the evaluation method of calculation of power losses in power transformer

Purpose. The purpose of the work is to perform analytical analysis of methods for calculating power losses of a power transformer and to improve the estimation method of calculation to increase the accuracy of calculating power losses on the example of an industrial power transformer.Methodology. Analytical and calculation method was used to determine power losses in the power transformer.Findings. Analysis of the main power losses of power transformers is an important task to determine the optimal conditions for their operation. Analytical analysis of transformer power loss calculation methods is carried out. The relative contribution of different types of power losses is shown. The calculation of energy losses of the power transformer TM 1000/10/0.4 is performed. The losses of active and reactive energy of the transformer are determined. The efficiency of the power transformer is calculated. A generalizing formula for determining the efficiency of the transformer is proposed.Originality. On the basis of the analytical analysis of methods of calculation of power losses of the power transformer the estimation technique is improved and calculation of losses of active and reactive energy of the industrial power transformer TM 1000/10/0.4 is carried out. A new generalizing formula for determining the efficiency of a power transformer, which takes into account the operating time of the transformer at maximum load, is proposed. Practical value. The estimation method for calculating the power losses of an industrial power transformer under load is improved, in which a generalizing formula for determining the efficiency of a transformer is applied. The proposed technique simplifies the calculations, reduces the estimated time to determine the operating parameters of the power transformer with the required accuracy. The proposed technique was tested on the example of the power transformer TM 1000/10/0.4. It is shown that with increasing maximum load time, the efficiency of the transformer increases and asymptotically approaches the maximum value.

Probabilistic impact of wind energy integration on distribution transformers

In traditional power grid, the direction of power flow of transformers is usually fixed in one direction. However, with the integration of the renewable energy sources, such as wind farms, the power flow in the grid becomes fluctuating and uncertain, which may cause the reverse power flow passing the transformer. For example, excessive reverse power flow may lead to the increase of transformer power loss and challenge the thermal stability of the transformer. This paper investigates the impact of wind energy integration on the existing power system infrastructure, such as distribution transformers. Probabilistic power flow (PPF) method is used for the analysis. Firstly, a sampling method based on Halton sequence is applied for PPF calculation. Then, to ensure the accuracy of probabilistic power flow calculation, the correlation between wind speeds of different wind farms is considered. A 30-Bus system is used for the probabilistic analysis of the transformer reverse power flow with different level of wind penetration. The results show that the reverse power flow of transformer may occur before 100% wind penetration is achieved. The higher the total wind power capacity in the grid causes the greater probability of transformer reverse power flow. Also, the location of wind farms will also affect the probability of transformer reverse power flow.

Electromagnetic-thermal analysis of 400 kV power transformer on ITER PPEN substation

As an important electrical power distribution system of ITER (International Thermonuclear Experimental Reactor) device, PPEN (Pulsed Power Electrical Network) feeds the pulsed loads for the superconducting coils and the heating and current driving systems. The PPEN transforms 400 kV power grid to 66 kV and 22 kV distribution voltage levels by 3 main step-down transformers. In this paper, the power loss of PPEN transformer is analyzed and calculated. The 2D PPEN transformer model is built. The temperature rise of PPEN transformer is calculated by ANSYS software. To validate the feasibility and correctness of the proposed method, the temperature rise test of PPEN transformer is carried out, then the related results are compared with the test data.

Analysis of the Impact of Electric Vehicle Charging Station on Power Quality Issues

Although, number of Electric Vehicles (EV) in Bangladesh are limited compared to conventional vehicles but in near future, expecting that the EV penetration will be increased significantly. Owing to environmental & socio-economic benefits with reduction of fossil fuel use, EV markets are expanding. These EV have a major impact on the power gird & distribution networks and due to the consequences of huge power demand to recharge their batteries. Large number of EV charging station when integrates with the utility grid, it produces harmonics, affect the voltage profile, finally affects the power quality. In this paper, the impact of electric vehicle charging station in Bangladesh on power grid and distribution networks is analyzed in terms of power demand, harmonics, Voltage sag & swelling and transformer power loss. Also, the mitigation technique for reducing power quality disturbances is analyzed in this paper.

Analysis of electromagnetic and loss effects of sub-harmonics on transformers by Finite Element Method

Power transformers are generally designed to be used in conditions where voltage and current are sinusoidal. However, nonlinear loads are increasing in modern power systems with the developing technology. Therefore, line voltages and currents often have harmonically distorted or non-sinusoidal waveforms. In this article, a model has been developed. The mathematically developed model has been proven experimentally and numerically. In this paper, different sub-harmonic content parametric analysis of the loss of transformer under no-load conditions with voltage excitation was performed. For this purpose, the Finite Element Method (FEM) based modeling of the core and windings of the transformer has been developed. An efficient method based on harmonic field model of transformer windings and FEM based modeling of transformer core is used. ANSYS@MAXWELL program, which realizes a solution based on FEM, is used for this. From the results of the analysis, it was seen that the effect of harmonic voltages on the loss of the transformer core is negligible. However, these tensions have been shown to increase winding losses in the unloaded state. This case reveals the importance of harmonics to be taken into account in calculating the losses of power transformers.

Calculation of DC Bias Reactive Power Loss of Converter Transformer via Finite Element Analysis

This paper proposes a novel and applicable approach to calculate the reactive power loss of converter transformer under dc bias. By using this proposed method, only general information of the converter transformer and the network is needed for the calculation within a certain dc current range. Specifically, a three-dimensional model of ±800 kV converter transformer model for simulation test is established by the finite element method. Through simulation test, the electromagnetic characteristics and reactive loss characteristics of converter transformer under dc bias can be obtained, and the relationship between the bias current and the reactive loss of ±800 kV converter transformer is quantified. Simulation results validate the feasibility of proposed algorithm.

Design and Realization of a Bidirectional Full Bridge Converter with Improved Modulation Strategies

In this paper a Full-Bridge Converter (FBC) for bidirectional power transfer is presented. The proposed FBC is an isolated DC-DC bidirectional converter, connected to a double voltage source—a voltage bus on one side and a Stack of Super-Capacitors (SOSC) on the other side. The control law aims at the regulation either of the bus current (when the load requires power) or of the SOSC current (when the stack requires a recharge). Analysis and design of the proposed FBC are discussed. A Phase Shift Modulation (PSM) scheme is proposed, along with an improved modulation variant for the efficiency optimization, through a proper reduction of the transformer power losses. The realized prototype, compliant with automotive applications, is presented and experimental results are highlighted. The target power level is 2 kW.

Reduction of electrical energy losses of power transformers of 25 kV traction substations

The aim of the study is to reduce the losses of electrical energy in power transformers of AC traction substations. To reduce the losses of electrical energy, interval counterregulation of performance indicators in the traction power supply system is performed. The planning of the electrical energy losses is determined by the predictive time intervals. The electrical energy losses in the time interval are determined by the power losses of instantaneous circuits. Instantaneous circuits determine the voltage of the windings of transformers, the currents of the power supply arms of the electric traction network, the transformation ratios, the temperature of the windings and the power of regional loads. The predictive values of the instantaneous circuits are determined by the results of the monitoring of the completed train schedules, statistical analysis and simulation modeling of the operation of the traction substation. The initial data for the calculation are the predictive discrete values of the performance indicators of the traction power supply system. The calculation of power losses in steel in power transformers is performed taking into account voltage unbalance. Copper losses are determined in phases, taking into account the distribution of arm currents in the windings and the actual transformation ratios. Actual transformation ratios are determined based on the voltage control stage. The effect of winding temperature on power losses is taken into account by the temperature coefficient of resistance. The number of transformers in operation at the predictive time intervals is selected by the minimum loss of electrical energy. The accuracy of the choice of the number of transformers in operation is checked by analyzing the implementation of the forecast train schedule. The error of the initial data and simulation modeling is determined by comparing the predictive values and the monitoring results. It is proposed to carry out performance management of the traction power supply system on the basis of digital technologies.