Power Losses In Transformers Research Articles

Reconfigurable topology assessment for efficient allocation of photovoltaic generators in unbalanced power delivery networks

The three-phase power delivery systems are reliable and efficient means of delivering electric power to customer node points. However, the unequal distribution of loads over the three phases leads to unbalance voltage between phases, resulting in increased power losses in distribution transformers and lines. It is highly challenging to install photovoltaic (PV) generators in unbalanced power distribution networks (PDNs) to restore power supply efficiency. This paper proposes dynamic reconfiguration (DR) in unbalanced PDNs to foster efficient integration of PV generators and improve system performance. Since the demand for electricity at residential node points and the PV-generated power varies with the season, this study proposes a seasonal DR of the PDNs. A framework with multiple objectives has been proposed for the DR-coupled PV deployment problem. A novel value-adaptive weight-aggregated (VAWA) grey-wolf optimizer (GWO) has been synthesized to contribute to system performance enhancement. The proposed strategy was validated and established through comparative investigations on an Indian 19-bus and modified IEEE 123-bus unbalanced radial distribution systems (URDSs).

PENYEIMBANGAN BEBAN TRANSFORMATOR DISTRIBUSI PCC-007 UNTUK MENGURANGI RUGI-RUGI JARINGAN PADA TEGANGAN MENENGAH 20KV

The distribution system of electrical power networks serves as a means to distribute electrical energy to both industrial and household consumers. With the increasing population growth, the number of electrical energy users or consumers also increases, potentially impacting the loading on each distribution transformer. If the loading on each transformer increases, it can lead to overload, load imbalance, power losses, and damage to the transformer. Therefore, to ensure the proper operation of distribution transformers, PLN (a state-owned electricity company in Indonesia) has set a standard for the loading on distribution transformers, which should not exceed 80%. This research aims to measure the loading on distribution transformers and analyze the occurrence of power losses caused by load imbalance. Measurements are conducted using a clamp meter and earth tester to obtain current and voltage values as well as the resistance value of grounding. Subsequently, calculations are performed for transformer loading, load imbalance, and power losses on the feeder.

Control strategy for flexible interconnection device considering transformer power losses

This paper proposes a flexible interconnection device control strategy. It takes transformer power loss into account to solve the problems of voltage overrun, station load imbalance, and unbalanced transformer capacity allocation that occur after the large-scale connection of distributed power sources into the low-voltage distribution network to realize the mutual aid of active power and load balancing between interconnected stations. Firstly, the VSC control strategy with capacitor current feedback active damping link is introduced to accurately execute the power commands and maintain the DC bus voltage stability. Then, the load regulation strategy with transformer power loss is proposed to generate the power commands of the flexible interconnection device. Finally, the simulation results show that the control strategy of the flexible interconnection device with transformer power loss mentioned in this paper can flexibly control the power transmitted by each port and maintain the bus voltage stability. The simulation results show that the flexible interconnection device control strategy proposed in this paper, which takes into account the transformer power loss, can flexibly control the transmission power at each port to keep the bus voltage stable. Moreover, it can effectively reduce system loss compared with the traditional load regulation strategy.

Enhancing heat transfer in power transformer radiators via thermo-fluid dynamic analysis with periodic thermal boundary conditions

The efficient dissipation of energy losses in electrical power transformers is crucial to prevent overheating of their windings and ensure proper functioning. In this study, we investigate the thermal design of a 30 [MVA], 132/34.5/13.8 [kV] power transformer radiator operating in Oil Natural-Air Natural mode by using Computational Fluid Dynamics (CFD) simulations. We introduce artificial body forces in the momentum Navier-Stokes equation to analyze the thermo-fluid dynamic performance of secondary transverse flows. Additionally, we propose a numerical scheme to solve the thermal equation with periodic boundary conditions using a reduced length of the oil channel, allowing for the decoupling of the thermal and fluid dynamic problems. To enhance the heat transfer, we propose the use of turbulators and wall indentation arrangements. Through our simulations, we analyze the effects of these enhancements on the cooling capacity of the transformer radiator. Our results demonstrate that these modifications increase the heat transfer coefficient and improve the cooling capacity of the radiator. Furthermore, we propose manufacturing considerations for the turbulators and wall indentation arrangements to ensure their practicality. Our findings provide valuable insights into the thermal design of power transformer radiators and demonstrate the effectiveness of turbulators and wall indentation arrangements in enhancing their cooling capacity.

Harmonic assessment on two photovoltaic inverter modes and mathematical models on low voltage network power quality

Power quality is a crucial aspect of designing a large-scale photovoltaic power plant, particularly regarding harmonics caused by inverter switching. This research aimed to analyze harmonics in a system using electrical transient analyzer program (ETAP) Power Station 20.5.0 to uncover the effect of irradiance on the inverters’ power quality running at 85% and 100% power factors. We analyzed both voltage and current total harmonic distortion (THD<sub>i</sub> and THD<sub>v</sub>) from the simulation and compared them with the mathematical model. Moreover, we analyzed the effect of changes in irradiance level on harmonics and reactive power penetration, which influenced power losses in transformers and cables. Inverters at 85% power factor experienced an increase in THD<sub>i</sub>, whereas those at 100% power factor decreased. Inverters with 85% power factor experienced more frequent switching, causing more prominent distortion. The magnitude of THD<sub>v</sub> increased proportionally with the rise of irradiance level. Inverters at 85% had a higher THD<sub>v</sub> value because of the excessive reactive power compensation when irradiance rose. Irradiance level had an inverse relationship with system losses since high irradiance levels led to lower losses as less power was required through transmission lines and transformers. Moreover, losses at 85% power factor were higher since the high harmonics caused additional losses.

Improved Methodology for Power Transformer Loss Evaluation: Algorithm Refinement and Resonance Risk Analysis

The decline in power quality within electrical networks is adversely impacting the energy efficiency and safety of transmission elements. The growing prevalence of power electronics has elevated harmonic levels in the grid to an extent where their significance cannot be overlooked. Additionally, the increasing integration of renewable energy sources introduces heightened fluctuations, rendering the prediction and simulation of working modes more challenging. This paper presents an improved algorithm for calculating power transformer losses attributed to harmonics, with a comprehensive validation against simulation results obtained from the Power Factory application and real-world measurements. The advantages of the algorithm are that all evaluations are performed in real-time based on single-point measurements, and the algorithm was easy to implement in a Programmable Logic Controller (PLC). This allows us to receive the exchange of information to energy monitoring systems (EMSs) or with Power factor Correction Units (PFCUs) and control it. To facilitate a more intuitive understanding and visualization of potential hazardous scenarios related to resonance, an extra Dijkstra algorithm was implemented. This augmentation enables the identification of conditions, wherein certain branches exhibit lower resistance than the grid connection point, indicating a heightened risk of resonance and the presence of highly distorted currents. Recognizing that monitoring alone does not inherently contribute to increased energy efficiency, the algorithm was further expanded to assess transformer losses across a spectrum of Power Factory Correction Units power levels. Additionally, a command from a PLC to a PFCU can now be initiated to change the capacitance level and near-resonance working mode. These advancements collectively contribute to a more robust and versatile methodology for evaluating power transformer losses, offering enhanced accuracy and the ability to visualize potentially critical resonance scenarios.

Study of the influence of the current distortion power of the secondary winding of a transformer on the level of losses in it using the method of experiment planning

Purpose. Detection the relationship between the level of losses of a three-phase transformer and the power of distortion caused by current harmonics.. Methodology. During the research, the methods of determining power losses and additional losses in the elements of the electrical system from higher current and voltage harmonics, the visual programming method, the experiment planning method, and the orthogonal central composite plan method were used. Findings. An analysis of the indicators characterizing voltage and current distortions was carried out, and it was found that these distortions are most fully characterized by the current distortion power and voltage distortion power. These indicators are used to analyze the transmission of electric energy by a transformer of a traction substation. It is noted that the order of harmonics in the distortion power is not eliminated, and higher harmonics are taken into account by the corresponding effective current of higher harmonics. The specifics of the transformer secondary winding connections to the consumer, namely the grounding of one of the secondary winding phases, were taken into account. A number of combinations of current harmonics were used to simulate current distortions. The experiment was carried out using the planning method. The coefficients of the quadratic regression equation that relates power losses to the level of load current harmonics of the third, fifth, and seventh orders are obtaine To determine the significance of the obtained coefficients of the regression equation, the variances and the corresponding values of the Student's criterion were calculated, as a result, factors that do not affect the process and can be excluded from the regression equation were identified. The adequacy of the obtained regression equation was checked by Fisher's criterion. The analysis of the effects and their interaction showed that the standard error of the sample does not exceed 1.66%. As a result of analyzing the combinations of current harmonics that were set during the experiment, it was noted that some of them lead to the same effective phase current, while the power of current distortion is different. The greatest significance of the level of the third harmonic of the current is determined. The constant level of active power on the high voltage side of the transformer is noted, which is due to the absence of voltage distortions on it. Originality. Cases of combinations of current harmonic levels at which the current distortion power index remains unchanged, while the level of transformer power losses caused by current harmonics changes, have been identified. Practical value. This research can be used to assess and reduce the level of power losses in a transformer by filtering certain current harmonics.

High-frequency transformers optimized design for power electronic transformers

Because of its small size, high frequency transformers are widely used to maximize energy transfer. However, the leakage inductance and distributed capacitance of high frequency transformer can not only cause resonance, but also lead to transient changes of voltage and current in high frequency, which can lead to voltage spike, so that the switch tube is damaged. For transformers with the same output power, high-frequency transformers are much smaller and have lower calorific value than low-frequency transformers. Therefore, at present, many consumer electronics and network product power adapters are switching power supplies, and the internal high-frequency transformer is the most important component of switching power supplies. The basic principle is to turn the input alternating current into DC first, and then turn it into high frequency through a transistor or FET, etc., through a high-frequency transformer to change voltage, and then rectify the output again, plus other control parts, and stabilize the output DC voltage. In this thesis, we choose a more rational and cost effective winding structure, choose a more appropriate core material based on the comparison of different core materials, research on the insulation and cooling properties of transformer so as to improve the insulation properties of the transformer, make it safer and more efficient. The study has important significance to decrease the power loss of high frequency transformer and decrease the size of high frequency transformer.

Analysis of Core Losses in Transformer Working at Static Var Compensator

This article presents the comparison of 3D and 2D finite element models of a power transformer designed for reactive power compensation stations. There is a lack of studies in the literature on internal electromagnetic phenomena in the active part of a transformer operated in these conditions. The results of numerical 2D and 3D calculations of no-load current and losses in the transformer core were obtained by using various methods and models. The impact of considering the hysteresis loop phenomenon on the calculation of core losses was investigated by using the Jiles–Atherton core losses model. The results obtained in the paper show that the model of the core must contain the areas representing the influence of overlappings on the no-load current and also on the flux density field in the core. The capacitive load of the transformer increases the flux density in the core limbs by several percent, so the power losses there must also increase accordingly. As a summary of the research, differences in the values of losses in each core element between the capacitive load and no-load conditions are presented. The results presented in this paper indicate that considering nonlinearity related to the magnetic hysteresis loop has a significant impact on the calculation of the core losses of power transformers.

Why Does the PV Solar Power Plant Operate Ineffectively?

Quality, reliability, and durability are the key features of photovoltaic (PV) solar system design, production, and operation. They are considered when manufacturing every cell and designing the entire system. Achieving these key features ensures that the PV solar system performs satisfactorily and offers years of trouble-free operation, even in adverse conditions. In each cell, the quality of the raw material should meet the quality standards. The fulfillment of the quality management system requires every part that goes into the PV solar system to undergo extensive testing in laboratories and environments to ensure it meets expectations. Hence, every MWh of electricity generated by the PV solar system is counted, the losses should be examined, and the PV system’s returns should be maximized. There are many types of losses in the PV solar system; these losses are identified and quantified based on knowledge and experience. They can be classified into two major blocks: optical and electrical losses. The optical losses include, but are not limited to, partial shading losses, far shading losses, near shading losses, incident angle modifier (IAM) losses, soiling losses, potential induced degradation (PID) losses, temperature losses, light-induced degradation (LID) losses, PV yearly degradation losses, array mismatch losses, and module quality losses. In addition, there are cable losses inside the PV solar power system, inverter losses, transformer losses, and transmission line losses. Thus, this work reviews the losses in the PV solar system in general and the 103 MWp grid-tied Al Quweira PV power plant/Aqaba, mainly using PVsyst software. The annual performance ratio (PR) is 79.5%, and the efficiency (η) under standard test conditions (STC) is 16.49%. The normalized production is 4.64 kWh/kWp/day, the array loss is 1.69 kWh/kWp/day, and the system loss is 0.18 kWh/kWp/day. Understanding factors that impact the PV system production losses is the key to obtaining an accurate production estimation. It enhances the annual energy and yield generated from the power plant. This review benefits investors, energy professionals, manufacturers, installers, and project developers by allowing them to maximize energy generation from PV solar systems and increase the number of solar irradiation incidents on PV modules.

Analysis of the impact of non-sinusoidal voltage levels in the power grid of apartment buildings on the reliability and efficiency of transformers

The effects of mass implementation of energy-saving lighting on the permissible level of loading of the supply transformer were analyzed. The influence of non-sinusoidal voltages and currents on transformer wear was analyzed. Distortions of sinusoidal shape of voltages and currents lead to additional power losses in transformer. They cause heating of the insulation and windings of the transformer, increased losses and accelerated wear and tear. Higher harmonic components of voltage and current in a 0.4 kV network are caused by the presence of various energy-saving lighting lamps with non-linear volt-ampere characteristic, which include compact fluorescent and LED light sources. As a result, the transformer designed to operate at a frequency of 50 Hz experiences an additional adverse effect in the form of power losses and accelerated wear of electrical insulation, which leads not only to the deterioration of its technical and economic performance characteristics, but also to a significant decrease in reliability associated with the influence of higher harmonic components of voltage and current on equipment failure. It is shown that the lack of power factor correction schemes for low-power compact fluorescent and LED lamps causes the growth of nonsinusoidal voltage and current as they spread, which in turn causes the need to adjust the limit load of transformers to ensure their rated thermal mode. One way to maintain operational reliability under such conditions is to limit the transformer load depending on the level of higher harmonics in the network, as well as to predict the residual life of the operating transformer. Measuring the values of current transformer load and current levels of higher harmonic components of voltage and current will allow not only to calculate an acceptable load factor of the transformer (for the condition of insulation wear), but also to estimate the current residual life of transformer equipment using a neural network model.

Power supply reactive power factor control as a function of consumer power and losses in transformers

The system of automatic control of the reactive power factor of the enterprise's power supply system is considered, in which one part of the transformer substations is equipped with adjustable capacitor units, and the second is not. Its advantage in comparison with the power factor control system is shown, firstly, lower requirements for its error and, secondly, the calculation of the consumer with the supplier for electricity is made taking into account the ratio of reactive energy to active energy. An estimate of the error of regulation of the reactive power factor on the higher voltage side of the transformers of the main step-down substation, where settlement meters are installed, is given, with stabilization of the reactive power factor on the low voltage side of these transformers. The synthesis of the system of automatic control of the reactive power factor, built as a function of the power of consumers and power losses in transformers, and the estimation of its error are considered. The proposed control system is intended for power supply systems with a combined load, the use of which will allow the consumer to avoid penalty coefficients to the tariff for active electricity, and ultimately reduce losses in the transmission of electricity and increase the transmission capacity of the electrical network.

Applications of Novel Heuristic Algorithms in Design Optimization of Energy-Efficient Distribution Transformer

Transformers are one of the crucial and expensive assets of a power grid. Reducing power losses in power and distribution transformers is important because it increases the efficiency of the transformer, which in turn reduces costs for the utility company and consumers. Losses in the transformer generate heat, which can reduce the lifespan of the transformer and require additional cooling. Additionally, reducing losses can help to decrease greenhouse gas emissions associated with the generation of electricity. This study presents an optimization method for transformer design problem using variables that have a great impact on the performance of a transformer. Due to the non-convex nature of the transformer design problems, the empirical methods fail to find the optimal solution and the design process is very tedious and time-consuming. Considering No Free Lunch (NFL) theorem, the design problem is solved using four novel heuristic optimization algorithms, the Firefly Optimization Algorithm (FA), Arithmetic Optimization Algorithm (AOA), Grey Wolf Optimization Algorithm (GWO), and Artificial Gorilla Troops Optimizer Algorithm (GTO) and the results are compared to an already manufactured 1000 kVA eco-friendly distribution transformer using the empirical methods. The outcome of the optimization shows that the suggested method along with the algorithms mentioned leads to a notable decrease in power losses by up to 3.5%, and a reduction in transformer weight by up to 8.3%. This leads to an increase in efficiency, decreased costs for materials, longer lifespan and a reduction in emissions. The developed model is capable of optimally designing oil-immersed distribution transformers with different power ratings and voltage levels.

Research on optimization strategy of transformer economic operation mode considering digital twin technology

Considering the overall environment of the power field, power transformer is one of the most important energy consuming devices in the substation, and the digital analysis technology of power transformer carbon footprint has become one of the hot issues. Taking a certain brand power transformer as an example, the no-load loss, load loss and stray loss of power transformer under different load conditions are calculated and analyzed by using electromagnetic finite element numerical analysis method, and then the digital twin model of power transformer is built. Combined with the digital twin model of power transformer, the carbon footprint of transformer is analyzed. Finally, the economic load coefficient of transformer is determined, and the optimal economic operation mode of substation is established. This method can provide a scientific basis for the construction of digital, low-carbon and energy-saving substations, while meeting the optimal efficiency and the fastest solution.

Increasing Efficiency by Applying a New Generation Dual-Core Transformer Design

In this study, in order to reduce the core losses of power transformers, the case of using two cores that can be activated according to the need instead of a single core is discussed. As it is known, in power transformers, the tolerance of core losses in the case of drawing the nominal power from the secondary depends on the materials used. In particular, the flux loss of the soft, siliceous sheet forming the core is tried to be improved by the manufacturing companies. However, if a small amount of the nominal power is drawn from this transformer while using a single core, core losses can be even greater than the power drawn. In the project of this study, a transformer with two different cores will be produced by dividing the core that will provide the total nominal power while manufacturing the transformer instead of a single core. Theoretical studies and simulation results show that this is possible. In the scientific literature, this situation is examined as a parallel study. It is known that transformers that show high variability in the amount of loading throughout the year in the national grid operate at a low occupancy rate. Instead of the single active core, the increase in the occupancy rate will make the second core active and meet the demand by working in parallel with the cores, which will contribute to the country's economy. Here, the switching on and off of the two cores placed in the same tank will be adapted considering the operating range of the cores with the highest efficiency by selecting the true direction of windings. Transformer prototypes to be produced within the scope of the new generation dual-core transformer project will be selected from among transformers with unbalanced load profiles in YEDAŞ responsibility areas, and transformers with a power of 2x50 kVA will be installed to be applied in pilot areas.

Calculation of specific electrical loads of residential buildings based on actual measurements

Updating the development of specific electrical loads of residential buildings of clusters 1 (up to 5 floors) and 2 (6-11 floors) based on actual measurements (with amendments to the Code of Rules 256.1325800.2016 "Electrical installations of residential and public buildings. Design and installation rules") contributes reducing the cost of technological connection in residential construction, as well as reducing the actual unused "locked power" at the same time as reducing electricity losses in power transformers. In the course of the study, an analysis has been made of the actual electrical loads of residential buildings in Moscow for the periods from November 1 to November 30, 2021 and from December 25, 2021 to January 31, 2022. The number of the studied sample for cluster 1 is 91 houses, for cluster 2 - 58 houses. When determining the maximum specific power of a sample set of multi-apartment residential buildings in Moscow in clusters 1 and 2, an average value and a confidence interval have been established, which "covers" the average of the general population with a probability of 95 %; a comparative analysis of the actual specific electrical loads of a residential building with the loads given in the Code of Rules has been carried out. Based on the results of statistical processing of a sample of multi-apartment buildings in clusters 1 and 2, the dependence of the maximum specific power on the number of apartments in a residential building has been determined with a trend line that clearly illustrates the trend in the studied dependence.

A Case Study for 50 kVA Toroidal Core Partially Superconducting Transformer

We report some numerical results obtained for 50kVA single phase partially superconducting toroidal and core power transformers. Transformers are calculated using the Comsol Multiphysics software with ac/dc and heat transfer modules. They are modeled in such a way that their primary parts (medium voltage) consist of copper windings and secondary parts (low voltage) are formed by superconducting MgB2 windings which are immersed into the liquid helium. Magnetic flux density profile on the iron core, primary and secondary currents, transformer power, and AC losses in superconducting windings are explored for one full cycle of AC voltage. Short-term temperature investigation for quenching showed that AC losses act as a heat source. We think that these numerical results are very important in terms of industrial-scale superconducting transformer applications because there are very few studies on MgB2 transformers. Our results will enable the design of toroidal-type power transformers that may be operable in practice. According to the numerical simulation results, it seems that a compact low cost superconducting MgB2 toroidal transformer can be realized with advances in cryostat systems and reducing AC losses. We suggest that the present study will contribute to the literature according to both the models applied and the results obtained.

Analysis of power loss in forward converter transformer using a novel machine learning-based optimization framework

Analysis of power loss in forward converter transformer using a novel machine learning-based optimization framework

Research of the Loss of Power Transformer Structure

This paper first introduces the research status of magnetic flux leakage and eddy current loss of power transformer at home and abroad, and discusses the significance and purpose of magnetic flux leakage and eddy current loss of power transformer metal components. At the same time, for the problems encountered in the calculation process of this paper, the corresponding solutions and the corresponding practical assumptions to simplify the calculation are given. In this paper, COMSOL software is used to establish the mathematical model of large power transformer and the actual three-dimensional finite element model of transformer, and the three-dimensional leakage magnetic field of large capa city transformer is accurately calculated. A surface impedance method based on double scalar magnetic potential is proposed. Using this method, the leakage magnetic field of structural parts of power transformer, such as pull plate, clamp, oil tank and so on, is analyzed and calculated The size and distribution of magnetic and eddy current losses. The simulation results are compared with the theoretical values to verify the validity and accuracy of the surface impedance method based on double scalar magnetic potential in analyzing the eddy current loss of large power transformer. Then this method is further applied to the analysis and calculation of magnetic leakage field and eddy current loss of a 6300kVA large power transformer to analyze the magnetic leakage field and eddy current loss of its metal components.

The magnetic flux density distribution in the anisotropic transformer core

The paper discusses the magnetic flux density distribution in medium power transformers core. Three-phase transformers are usually made of grain-oriented electrical steel characterized by anisotropy. Core losses, among other things, mainly depend on the grade of material. The selected results of calculation and measurement of no-load losses of medium power transformers have been shown.