Distribution Transformer

A generalized macroscopic representation of electrical steels used in transformer manufacturing industry is developed. The proposed representation is specifically formulated for integration in the finite element method. Usage of the specific technique enables the accurate evaluation of electromagnetic field distribution of transformer cores under heavily saturated conditions. Advantages over conventional techniques include numerical stability, numerical accuracy, and reduction of iterations of the Newton–Raphson method.

In this paper a robust three-dimensional (3D) finite element (FE) anisotropy model is introduced based on a particular scalar potential formulation. The specific 3D FE model is suitable for the accurate evaluation of the peak flux density distribution and no load loss of one-phase and three-phase wound core distribution transformers. The accuracy of the proposed 3D FE anisotropy model is validated by local flux density and no load loss measurements.

Transformers are important elements in the process of transmission and distribution of electricity. Transformer is one of the vital and costliest components of electrical industry. As large number of distribution transformers are installed over a wide area, monitoring and maintenance of these transformers is an important issue. Therefore this paper presents the system which monitor different parameters of distribution transformer and these data are continuously updated on to a webpage using IOT. If any abnormality occurs, the system sends alert messages to the concerned person and an electronic relay operates. As the inductive load increases there will be a decrease in power factor, therefore this system incorporates a power factor improvement mechanism by switching capacitor banks. The main objective of this project is to develop a system which will help the utilities in the protection of transformer and identify problems before any catastrophic failure.

This paper presents design and implementation of a mobile embedded system to monitor and record key operation indicators of a distribution transformer like load currents, transformer oil and ambient temperatures. The proposed on-line monitoring system ...

Even though, the transformer is the most efficient of electrical machines, with efficiencies typically in the high 90s, it is possible to reduce transformer costs and losses by using composite magnetic cores. This paper presents a new composite magnetic core that can be used effectively for manufacturing single–phase and three–phase wound core distribution transformers. The new composite wound core concept is based on experimental evidence concerning the flux density non–uniformity of conventional single–phase and three–phase magnetic wound cores and the losses and magnetization properties of conventional and high permeability Si–Fe grain–oriented steels. A systematic experimental losses and flux distribution analysis of single phase and three–phase magnetic wound cores is undertaken as well as finite element (FE) analysis considering the bulk anisotropic characteristics of laminated wound cores.

The losses in European Union distribution transformers are estimated at about 33 TW · h/year, whereas reactive power and harmonic losses add a further 5 TW · h/year. The reduction of distribution transformer no-load loss is particularly important as the ratio of no-load to load losses is nearly three. In this paper, the no load operation of wound-core transformers under sinusoidal and distorted supply-voltage conditions is investigated. For that purpose, a 2-D nonlinear transient finite-element analysis taking into account hysteresis has been developed. The hysteresis model is based on a modified Jiles–Atherton representation, and the proposed analysis is compared to experimental data.

Distribution transformers of substation are one of the most important equipment in power system network. Because of the large number of transformers and various components over a wide area in power systems, the data acquisition, condition monit oring, automatic controlling are the important issues. This project presents design and implementation of automatic control circuits using power line communication to monitor as well as diagnose condition of transformers, like over voltage, over currents, temperature rise and oil level. The suggested power line communication monitoring system will help to detect internal faults as well as e xternal faults of transformer and also diagnose these faults with the help of desired range of parameters which is sett ing by programmer.

In any Power System, the Transformer plays a vital role. Monitoring of the physical parameters of a transformer meets many challenges. At present, Distribution Transformers need development of the data-acquisition system that can be used for condition monitoring, which helps in fault detection as well as preventive factors. The main objective of the system presented in this paper is to monitor the parameters of the transformer remotely through Global System for Mobile (GSM), which will avoid need for any manual operator and thus reduce human efforts. We have proposed the embedded system design, to monitor parameters such as voltages, currents and temperatures. This System is remotely located at the transformer site in a control cabinet which collects and analyzes all data. This system performs tasks of reading sensors, analyzing data and remote monitoring. ATMEGA2560 Arduino is used to control, process and communicate between modules. The remote monitoring of the transformer through GSM is a time saving and effortless system.

Utilities deliver power to their customer through a
network of generation, transmission lines, substation &
distribution system. A distribution system carries power from
substation transformer through feeder circuit to distribution
transformer located near customer. Distribution spending is one
of the largest costs for most utilities also cause of concerns as
network increases day by day along with the increasing power
demand. Utilities are constantly looking forward to increase
productivity in the distribution system. This means reducing
losses, improving customer service & protecting assets. A
Distribution transformer is utilized to step down the voltage
from 11 KV to 0.433/.250 KV so that the electrical power is
usable for providing supply to customer such as domestic,
industrial, etc. A consumer expects uninterrupted power supply
because during failure of power all work be it domestic, official,
industrial comes to standstill. Hence, transformer failure leads
economic loss, interrupted power supply in industries, offices.
This paper present types of failure in distribution transformer,
means for reducing distribution losses & recent practices in this
regards by Gujarat DISCOM.

Transformer gets a vital role in transmission and distribution of electric power. Reducing the failures ensures an increased chance of uninterrupted power to be supplied to consumers. Overload, Voltage fluctuations and heating up of transformers causes severe damages to the 829 transformers, which takes much time and a lot of expenses. Major portion of the losses in the power system networks is attributed towards the use of distribution transformers (DT). Excess thermal losses in DT become an unsolved major hazard. Only under heavy loads, the winding losses and saturation comes into consideration. A proper monitoring scheme is designed based on the monitoring of key operating parameters of the distribution transformer. The system is intended on providing essential data regarding the wellbeing of DT. The utility system would make use of the data for optima avocation of available resources, which is DT in this case. The monitoring provides an easier approach to deal with all interruptions, from minor to the most catastrophic failure. In other words, an optimal monitoring setup to maintain the reliability of DT's.

Nowadays, transformers are made of conventional magnetic cores which are constructed of a single grainoriented or amorphous, magnetic steel. Even though, the transformer is the most efficient of electrical machines, with efficiencies typically above 90%, it is possible to improve transformer performance by using composite magnetic cores. Patents related to this simple and effective technique can be traced back to 1929. The specific technique can be applied to wound core distribution transformers. By using wound cores constructed with a combination of conventional and high permeability grain-oriented steel the total owing cost (TOC) of the transformer can be reduced effectively. This paper presents a brief review of patents on wound and composite magnetic cores and introduces a generalized technique for the determination of the optimum design variables of a new composite wound core design.

This paper proposes the manufacturing of distribution transformers using a novel type of magnetic core which is called composite wound core. A composite wound core is constructed of a combination of conventional and high magnetization grain-oriented steel. The main advantage of transformers assembled of composite wound cores over conventional transformers is the significant reduction of the manufacturing and operating cost. For the analysis of composite wound core transformers, a FE model considering anisotropy and high saturation conditions, and an advanced 3D hybrid FE-BE model have been developed.

With increasing competition in the global market continuous research are done to optimize the behavior of materials to be used in transformer. Since silicon (Si) comprises a very good crystallographic arrangement then that of iron (Fe), silicon is fused with iron for considerable reduction of leakage flux in it. A novel M19 high grade silicon steel core has been introduced for 1 KVA 415/230V delta to star connected distribution transformer and stray losses are estimated using Ansys Maxwell. The obtained results are validated by experimental test.

There have been incessant power failures in our power network, which has arisen as a result of over current, over voltage, harmonic distortion caused by ripples to mention a few, This could be overcome by determining the harmonic mean from a given harmonic distortion data ,optimizing the mean from a given distortion data, training the optimized result to minimize harmonic in power distribution transformer, designing a Simulink model for mitigating the resultant effect of harmonics which are the sinusoidal components of a complex wave, using simplex optimization technique. The optimization technique used is 69% better than the conventional method like proportional integral derivative (PID) in terms of minimizing harmonic in power transformer.

This paper shows experimental results of longitudinal flux density and its harmonics at the limb, the yoke and the corner of a three phase, Si-Fe, five-legged wound transformer core. Results show that the flux density is nonuniform in the cores and there is high level of third harmonic component. Moreover, the lower flux values in the outer cores have been assessed and the simultaneous time variation of the flux in both outer cores has been demonstrated by measurements while the peak magnetic flux density values have been compared to FEM analysis. These findings enable a better understanding of the magnetic behavior of five legged wound transformer cores and their consideration is expected to achieve respective improvement of the design with respect to core losses and magnetostriction noise.

The importance of distribution transformer noload
loss on the operation of modern electrical grids is often
underestimated. Internationally, distribution transformer no load loss constitutes nearly 25% of the transmission and
distribution losses of electrical grids. The losses in European
Union distribution transformers are estimated at about 33
TWh/year whereas, reactive power and harmonic losses add a
further 5 TWh/year. In the Greek electrical grid the no-load
losses of 140,000 distribution transformers are estimated at
about 490 GWh/year. This paper has two goals: The first one is
to illustrate the significance of distribution transformer noload
loss in periods of high electric energy cost. The second
goal is the presentation of a novel numerical methodology for
wound core transformers no load loss analysis, enabling to
determine the economically and technically optimum transformer for every use, which has been developed in the
frame of the respective research project.

In recent years, researchers have proposed transformerless solutions for connecting renewable-energy power plants to the grid. Apart from lack of efficiency and increased cost and weight of the transformer, one of the reasons is the dc input current that causes transformer saturation. The purpose of this paper is the development of a finite-element computational tool that is going to aid transformer manufacturers in designing distribution transformers specifically for the renewable-energy market. It is based on a generalized macroscopic representation of electrical steels used in the transformer manufacturing industry that enables the accurate evaluation of electromagnetic field distribution of transformer cores under heavily saturated conditions. Its advantages over conventional formulations include numerical stability, numerical accuracy, and reduction of iterations of the Newton–Raphson method. An experimental verification of the proposed method is carried out.

Distribution transformer operation is sensitive to
the distortion of the supply voltage waveform. According to
Strategies for development and diffusion of Energy Efficient
Distribution Transformers (SEEDT), reactive power and
harmonic losses add a further 5 TWh/year to the losses of
European Union (EU-27) distribution transformers. In the
present paper a systematic experimental procedure is
developed in order to evaluate the effect of voltage harmonics on distribution transformer operation. Also, a theoretical analysis based on the hysteresis design tool of Matlab and a finite element code integrating the hysteresis phenomena is carried out.

Distribution transformers losses are equal to almost 2% of the electricity generated worldwide and only in the European Union are estimated at about 33 TWh/year. Approximately 75% of the total losses are due to core losses as a result of the loading characteristics of distribution transformers. Design of the joints of magnetic cores has a profound impact on core losses and transformer efficiency. The paper introduces a finite element methodology for the analysis of transformer joints. The proposed technique consists in the application of certain boundary conditions for the excitation of the joints. The main advantages of the pseudo-source technique include minimization of the computational cost and ease of implementation. The technique is combined with a number of FE formulations and a vector hysteresis model. Two-dimensional as well as 3-D FE analysis is studied. Longitudinal and normal flux measurements were carried out for the validation of the proposed technique.

The total owning cost of a wound core distribution transformer can be reduced by constructing the wound core with a combination of conventional and high permeability grain-oriented magnetic steel. The proposed technique can be applied after the transformer’s design optimisation or it can be integrated in the design optimisation procedure. In both cases a significant reduction of the total owning cost is achieved.

In this paper, the sensitivity analysis is used to select the core lamination thickness of single-phase distribution transformers rated from 5 to 50 kVA. Three different magnetic materials (M2, M3 and M4) with thicknesses of 0.18, 0.23 and 0.27 mm are considered. Transformer designs are compared based on the total owning cost as well as on the transformer bid price. The impact of the different laminations on total owning cost and bid price is calculated for a total of 144 transformers (72 for each criterion). All transformers fulfill all the operating and construction constraints. The paper considers the impact on core losses of the space factor (core-assembling pressure) and of the building factor and also describes how core losses are affected by core design parameters such as the number of laminations per step, air gap and overlap. It is concluded that for the analyzed power range, M3 lamination is the best choice since all of the studied cases have smaller bid price and 79% of the studied cases have lower total owning cost. This paper gives guidelines to select the appropriate thickness and can help transformer manufacturers to select the optimal thickness for distribution transformers.

This article compares the total mass and the total owning cost (TOC) of three-phase distribution transformer banks with standard three-phase distribution transformers. The comparison is based on the minimum TOC. This is achieved through a field-validated distribution transformer design program that automatically minimises the objective function (TOC). In particular, 12 oil-immersed distribution transformers are designed: 6 three-phase transformer banks and 6 three-phase transformers; these designs meet all the requirements of a given transformer standard. As a result, curves of minimum TOC versus transformer rating are obtained for three-phase transformer banks and three-phase transformers. Moreover, similar curves from seven transformer manufacturers are collected; the advantage of this collection is that these different manufacturers have different types of transformers: oil immersed or dry type, core or shell type, various voltage classes and power ratings, and so on, and consequently more general conclusions can be drawn regarding the comparison of three-phase transformer banks and three-phase transformers. From these investigations, it was found that from the viewpoint of minimum total mass and minimum TOC, three-phase transformer banks should be recommended in case of small-size transformers (rating lower than 45 kVA). This is an important finding that is not emphasised in recommended practices reported in transformer textbooks.

This paper introduces a novel technique for iron loss minimization of wound core transformers. The proposed technique involves the evaluation of appropriate design variables of wound cores constructed by a combination of standard and high magnetization grade steel. The evaluation of the optimum design variables of the multiple grade lamination wound core is achieved by combining a permeability tensor finite-element model and simulated annealing with restarts.

This paper proposes a three-phase five legged wound transformer core constructed of two high permeability Si-Fe wound cores and two conventional Si-Fe wound cores. The two large internal wound cores are manufactured of high permeability, grain-oriented electrical steel. The two small outer wound cores are manufactured of conventional, grain-oriented electrical steel. The specific arrangement is based on experimental evidence concerning the peak flux density non-uniformity of the typical three-phase five legged wound transformer core, constructed of the high magnetization grain-oriented steel. Since the peak flux density of the two outer cores is lower than the two internal cores, low cost, low permeability, conventional grain-oriented electrical steel can \ be used for the outer cores. Losses, excitation currents, flux waveforms, and their harmonics contents are presented in this paper. A comparison of the mixed three-phase transformer core and the typical one is also carried out.

Purpose – This paper aims to present an accurate representation of laminated wound cores with a low computational cost using 2D and 3D finite element (FE) method.
Design/methodology/approach – The authors developed an anisotropy model in order to model laminated wound cores. The anisotropy model was integrated to the 2D and 3D FE method. A comparison between 2D and 3D FE techniques was carried out. FE techniques were validated by experimental analysis.
Findings – In the case of no-load operation of wound core transformers both 2D and 3D FE techniques yield the same results. Computed and experimental local flux density distribution and no-load loss agree within 2 per cent to 6 per cent.
Originality/value – The originality of the paper consists in the development of an anisotropy model specifically formulated for laminated wound cores, and in the effective representation of electrical steels using a composite single-valued function. By using the aforementioned techniques, the FE computational cost is minimised and the 3D FE analysis of wound cores is rendered practical.

Monitoring the insulation status of a transformer requires the availability of accurate information of the oil temperature at any moment. Considering the importance of oil temperature prediction in oil-immersed transformers and its direct relation with the life of transformer, a novel model is presented in this paper using the concept of thermal resistance with consideration of solar radiation for expressing the heat transfer in distribution transformers. The results of the proposed model are compared and validated with experimental results. These results show that in the studied transformer and rated loading, solar radiation can increase the oil temperature by about 3.7°C. In this paper, the thermal resistance model with solar radiation is used to predict the thermal behavior of the transformer in overloading condition. Finally, the transformer operation with/without consideration of solar radiation effect is studied and its impact on the transformer's loss of life due to the increase in oil temperature is investigated. In order to consider the effect of solar radiation on oil temperature, new equations using the concept of thermal resistance are presented to calculate the shadow surface created on the fin-folded transformers, and a novel equation is proposed for permissible loading of distribution transformers.

Transformer no load loss optimization is crucial for transformer manufacturers as well as for electric utilities, since it results to significant economic benefits. In this article, the three-dimensional finite element analysis is applied to power transformers in order to predict and minimize the iron loss. The proposed model is based on a particular reduced scalar potential formulation, necessitating no prior source field calculation, and employs detailed modeling of the core geometry and material, considering for manufacturing core formation process effects by convenient hysteresis phenomenological models. Comparisons between this method and test values for a number of commercial transformers, prove its validity and accuracy, rendering it a reliable tool for customized design of an industrial plant

In the present paper, a Transformer Design Optimization (TDO) software package is developed providing a user-friendly transformer design and visualization environment. This software consists of a collection of design optimization, visualization and verification tools, able to provide transformer designers all the proper interactive capabilities required for the enhancement of the automated design process of a manufacturing industry.

In the energy distribution networks, the most important and valuable equipment is oil-immersed distribution transformers. Besides, due to the key role of these transformers and their multiplicity, their lifetime monitoring is inevitable. The life of a transformer depends on the weakest solid insulation material (i.e. paper insulation). On the other hand, monitoring the transformer insulation status requires accurate information to be available about the oil temperature at every moment. Therefore, it is important to control and predict the oil temperature rise in the transformer. In this study, a new model based on fundamental heat transfer theory is proposed for thermal behaviour prediction of top oil of indoor distribution transformers using the concept of thermal resistance, namely electro-thermal resistance model (E-TRM). In E-TRM, the thermal resistance network is formed by following three-dimensional heat transfer path and assigning thermal resistance to each path. To evaluate the proposed E-TRM, the results of this model are verified with experimental results. Moreover, the E-TRM is used to predict the thermal behaviour of the indoor transformer in the overloading condition. At the end, the transformer loss of life is estimated based on the oil temperature and a normal cyclic overloading strategy is presented for overloading management.

There have been incessant power failures in our power network, which has arisen as a result of over current, over voltage, harmonic distortion caused by ripples to mention a few, This could be overcome by determining the harmonic mean from a given harmonic distortion data ,optimizing the mean from a given distortion data, training the optimized result to minimize harmonic in power distribution transformer, designing a Simulink model for mitigating the resultant effect of harmonics which are the sinusoidal components of a complex wave, using simplex optimization technique. The optimization technique used is 69% better than the conventional method like proportional integral derivative (PID) in terms of minimizing harmonic in power transformer.

The importance of the distribution network is not overlooked by anyone. The transformer is one of the key equipment in this network. Therefore, great care and attention are needed in its design, maintenance and operation. Most of the oil-immersed distribution transformers are operated under solar radiation conditions. However, increasing the oil temperature due to solar radiation is not considered in their design. This increases the oil temperature above the design temperature value and thus reduces the life of the transformer. In this paper, due to the lack of specified equations for solar energy absorption by the fins and tank of the transformer, a novel method and equation are proposed for the calculation of the transformer solar radiation absorption amount. As well as, the effect of orientation on the corrugated tank distribution transformers oil temperature is investigated using the Electro-Thermal Resistance Model (E-TRM). For this purpose, two identical transformers with different orientations are tested experimentally and the results are compared and verified with the numerical results. The transformer tank color is one of the effective factors of solar radiation absorption. Depending on the absorption and emission rates, the effect of the different colors of the transformer tank on the oil temperature in different loading is investigated in this paper. The results show that the use of bright colors in comparison with dark colors can lower the oil temperature by about 3°C on the rated loading of the transformer. In order to consider the effect of solar radiation on the transformer, the modified ambient temperature is introduced for the design of the transformer. Finally, the effect of transformer operation under solar radiation and with different colors is investigated and transformer loading de-rating is proposed by a novel equation. Ó 2020 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The paper presents a three-dimensional finite element (3D FEM) anisotropy model, based on a particular scalar potential formulation, for the no load loss evaluation of wound core shell type distribution transformers. The specific 3D FEM anisotropy model is combined with a hybrid finite element-boundary element (FEM-BE) model, used for the calculation of the transformer’s short circuit impedance, and various optimization algorithms in order to minimize the total owing cost (TOC) of a distribution transformer.

The importance of distribution transformer no-load loss on the operation of modern electrical grids is often underestimated. Internationally, distribution transformer no-load loss constitutes nearly 25% of the transmission and distribution losses of electrical grids. The losses in European Union distribution transformers are estimated at about 33 TWh/year whereas, reactive power and harmonic losses add a further 5 TWh/year. In the Greek electrical grid the no-load losses of 140,000 distribution transformers are estimated at about 490 GWh/year. This paper has two goals the first one is to illustrate the significance of distribution transformer no-load loss in periods of high electric energy cost and the second goal is the presentation of a novel numerical methodology for wound core transformers no-load loss analysis, enabling to determine the economically and technically optimum transformer for every use.

Distribution transformer is a step down transformer which converts high voltage level to low voltage level. The main aim of this proposed system is to real time monitoring and finding the faults occurred in distribution transformer like Load current, Temperature, Oil level indication of the distribution transformer with the help of IoT (Internet of Thing).This system also provides power man safety during maintenance work. This will help to reduce the working effort and protect the distribution transformer by identifying faults before failure and actions can be taken.

—Planar Rogowski Current Sensor works on the principle of electromagnetic induction as conventional iron core current transformers. In iron core current transformer, the core saturates beyond a certain current value which introduces nonlinearity in the desired output. Unlike iron-core current transformer, planar rogowski is an air core device and used for measuring alternating and transient currents. A Planar Rogowski current sensor suitable for high current measurements especially for the application of three phase distribution transformer is designed. In order to develop a sensitive and accurate Planar Rogowski current sensor a systematic approach involving electromagnetic analysis and simulation of printed circuit board (PCB) based rogowski current sensor is discussed. Design calculation is validated by developing prototype and testing. Sensitivity analysis and linearity in the output voltage is studied.