Distribution Transformer Design Research Articles

Rehabilitation and Techno design of Distribution transformer and 11kV feeder of a radial distribution system

In any transmission and distribution system- the performance of that system mainly depends on voltage regulation and efficiency. Hence for the better operation of the system, it is required to maintain constant voltage regulation with good power factor and low power loss throughout the feeder. This can be achieved by using various methods. Out of those, placement of a capacitor bank at the densely loaded areas is the best-proven method compared to any other method. This research work considered the feeder-5 of the Al-Uwainath primary substation which was suffering from low voltage–poor regulation- problems. Here in this research modeled and analyzed 3 different techniques for rehabilitation to this low voltage, poor regulation, and power factor problem and recommended the most efficient method out of the three methods. As a part of this project simulated the same conditions of the site after collecting the data of the feeder from the site by using ETAP software and checked the performance by calculating its voltage regulation, power losses, and power factor in all three 3 different methods and recommended the most efficient method of feeder-5 rehabilitation by comparing the results of three methods with the exciting system.

"Power Transformer Design Optimization and Productivity Evaluation Using Artificial Intelligence Techniques"

Transformers need to be designed in a way that satisfies not only all international requirements and customer expectations but also that they are effective, economically practical, and satisfy all international criteria. The design of a transformer should ultimately achieve this goal. It is anticipated that the costs of active components, development, and ownership will decrease as the application of AI approaches becomes more widespread. This is expected to occur while maintaining compliance with international standards and constraints. Using the AI technologies that are currently being utilized in Indian manufacturing will not be sufficient to solve TDO issues. The current research is focusing on developing artificial intelligence-based solutions that have the potential to be used to improve the design of distribution transformers. By utilizing this design for the transformer, both the total ownership costs and the expenses associated with its manufacture would be cut in half (TOC). It was demonstrated that when attempting to solve TDO problems using techniques such as GA, PSO, and TLBO, PSO and GA found higher objective feature values than GA. When it comes to percentages, TLBO performs significantly better than both PSO and GA. As a result of the implementation of NSGA II, the TOPSIS technology made it possible for DM to select any solution from among the non-dominated solutions

Electromagnetic modeling of 35kV distribution transformer lightning overvoltage and its prevention method

Distribution transformers are important power conversion equipment, whose safe and reliable operations affect the power supply quality of the distribution network. In order to analyze the lightning strike fault of distribution transformers, some more reasonable protection measures of transformers could be put forward. In this paper, a 35kV distribution transformer under the lightning strike is taken as the research object. Firstly, the lightning overvoltage model of the distribution transformer was established with the method of the double exponential model. Secondly, through the simulation of the distribution transformer, it was found that the electromagnetic transient distribution change dramatically, which will quickly cause the winding current flickering and form the winding overvoltage. Finally, through the voltage distribution law and the magnetic flux distortion of the transformer, it can be seen that the lightning overvoltage has a serious effect on the electromagnetic parameters of the transformer. The protection scheme is briefly analyzed, which has a guiding significance for the lightning protection design of distribution transformers.

Technical and economical evaluation of distribution transformer with amorphous metal core in Indonesia

High efficiency electrical equipment usage is an alternative solution to support carbon emission reduction in Indonesia. In this research, new distribution transformer design using amorphous metal core (AMDT) was evaluated by conducting laboratory testing and field installation. According to the laboratory test result upon 4 samples, AMDT had 60.91 – 67.35% smaller no-load loss but 0.58 – 9.79% higher load loss compared to national standard requirement (although the load loss value of AMDT was within total losses tolerance). One AMDT sample failed during impulse test which should be followed up further by conducting insulation testing and design evaluation. Since the AMDT sample used 5-legged core design, the weight of the AMDT was heavier than conventional cold rolled grained oriented (CRGO) silicon steel transformer; thus, the construction planning and design should be re-evaluated for AMDT installation. According to total cost calculation based on life cycle approach by using obtained data and related assumptions, it was found that AMDT would potentially give higher economic benefit than conventional CRGO silicon steel transformer when the load factor (LF) is below 79% for 100 kVA AMDT, below 78% for 50 kVA AMDT, and below 68% for 25 kVA AMDT.

Considering Environmental Health and Energy Resources to Design Transformers

Background: Environmental health has become a worldwide debating issue among researchers, scientists, and governments. Although fossil fuels have been the greatest energy resources for the human, their consumption leads to injecting greenhouse gases into the air, which can affect the existence of all living species dramatically. In fact, fossil fuels consumption pollutes the environment because of the injection of greenhouse gases which result in global warming. On the other hand, reductions in fossil fuel and drinking water resources have highlighted the importance of energy management and loss reduction in brand-new management strategies and manufacturing methods. Distribution transformers are one of the most used devices in power distribution networks. Hence, it seems to be logical to consider transformer losses as a definitive factor in design and construction procedures. Furthermore, such design procedures require powerful tools to solve complex non-linear equations and find the best solutions in the shortest time. Researchers and scientists have always had a great challenge regarding finding the best solutions for their analysis. In actuality, it is hard to solve complex non-linear problems by means of traditional calculation methods even if a researcher employs a powerful computer. For this reason, metaheuristic optimization algorithms have found great popularity among scientists. These algorithms seek the best solution through a solution pool at an appropriate pace. Therefore, a researcher can save more time and energy in solving an intricate problem. Objective: In this paper, the authors aim to modify the conventional Teaching-Learning Based Optimization (TLBO) algorithm to design an optimum distribution transformer by consideration of the transformer Total Owning Cost (TOC). The TOC consists of operational and initial manufacturing costs of a distribution transformer. The used raw materials affect the manufacturing cost and it would be decreased if the copper and iron volumes are reduced in the construction instruction. However, the operational cost that includes iron and copper losses must not be forgotten in design analysis. Indeed, loss consideration is of great significance to keep energy from frittering away and as a result, protects environmental resources. Materials and Methods: A novel approach based on an optimization technique for distribution transformer design problems is presented in this paper. The entire expenses of a transformer consist of transformer construction and operating costs. In other words, by reducing copper and iron volumes, the initial cost of a transformer will be decreased. Due to the electromagnetic and electrical losses in transformers, the initial cost of a transformer is not its entire design problem and the operating cost must be considered in the design algorithm. Appropriate limits on efficiency, voltage regulation, temperature rise, no-load current and winding fill factor are the constraints on the transformer design problems in the international standards. With respect to these constraints, the transformer designer can minimize the volume of the core and windings. In this paper, the Conditional Teaching-Learning Based Optimization (CTLBO) algorithm determines the appropriate transformer properties, while transformer construction cost and its operating cost are selected as an objective function for optimization method. In order to attain a suitable voltage regulation, transformer impedance is chosen as an optimization constraint. Results: The result of the paper demonstrates the proposed algorithm ability in reducing the Total Owning Cost (TOC) during transformer lifetime, which could be useful for energy distribution companies. In addition, the result analysis proves that the total losses of the transformer are reduced by the proposed approach in comparison to conventional design techniques. Then, more energy will be saved in the power grid when the proposed transformer is utilized in the power network. Conclusion: In this paper, a suitable method to design an optimum distribution transformer is proposed which enables manufacturers to construct their product based on the proposed method. In this way, it can be claimed that not only more money will be saved during the transformer operation, but also the energy consumption will be decreased drastically. Therefore, world resources will remain for future generations.

Active System Grounding With a Novel Distribution Transformer Design

A novel Wye-wye transformer design for active system grounding, is described in this paper. Proposed as a solution to improve the ground fault performance in distribution line networks, the zero-sequence flux developed in the magnetic core of a transformer is on a ground fault harvested by coils wound around three limbs, or extra limb(s) in a Wye-wye transformer. Built with three limbs, and no tertiary winding, the flux developed in the core on a ground fault is forced to return through air, which has a high reluctance, but with four or more limbs, the flux circulates in the transformer magnetic core, which has a low reluctance. Connected to one or more single-phase windings, the transformer neutral current is on a ground fault actively altered by fixed and switched load impedances. In theory, a ground fault arc is with a low current and delay in recovery voltage self-extinguishing, and no interruption in supply is required, but sustained, must be isolated. Proposed in this paper, for an active load switched grounding method, the neutral current on a sustained ground fault is increased to enable plain overcurrent and fuse protection to operate without the need of sensitive directional relay protection.

Analysis of Winding Temperature and Design of Distribution Transformer for Improving Short Circuit Withstand Capability under Renewable Generations Mixed Environment

Analysis of Winding Temperature and Design of Distribution Transformer for Improving Short Circuit Withstand Capability under Renewable Generations Mixed Environment

SF6 gas-insulated 50-kVA distribution transformer design

There are increasing environmental concerns such that governments are pressured to cooperate with international concurrences. One of the most harmful contaminants is mineral oil when it infiltrates the soil. Although it is a good material in the act of insulating in distribution/power transformers, it presents some environmental hazards and safety disadvantages. For this reason, gas-insulated transformers are considered particularly for hazardous locations. An oil-insulated distribution transformer of 50 kVA, 34.5/0.4 kV, and 50 Hz is investigated and converted to SF6 gas-insulated transformer in this study. The suggested distribution transformer model with SF6 insulated has many benefits, such as being explosion-proof and light, with a compact design. Therefore, the new design provides a safer transformation for security risk environments such as nuclear power plants, mines, and submarines. The prototype is more compact and proposes lighter designs between 25{\%} and 55{\%} as compared to conventional oil-insulated transformers. COMSOL is used for modeling and breakdown optimization studies.

Design optimization of distribution transformers by minimizing the total owning cost

Summary This paper presents a new optimization problem for the design of distribution transformers under the strict requirements on energy efficiency imposed by modern standards and directives. The proposed methodology is devoted to the minimization of the total owning cost of the transformer while meeting a set of constraints that includes all the phenomena implied in the transformer operation. In particular, both electromagnetic and thermal aspects are considered and their relationships with electrical and geometrical variables are accurately detailed. Furthermore, the power losses in both core and windings are accurately derived and the limitations imposed by the standards are taken into account by imposing proper constraints. The generality of the proposal allows considering different technological solutions in material used for the core. The results proposed in the numerical applications showed the effectiveness of the proposed procedure and permitted highlighting the feasibility of different solutions.

Development of an efficient distribution transformer using amorphous core and vegetable insulating oil

This paper presents the development of an efficient distribution transformer, based on amorphous core and vegetable insulating oil. Significant reduction was obtained in no load losses and guaranteed operation in higher temperatures, along with the fact that the fluid is non-toxic and of fast biodegradation. A distribution transformer design methodology considering the total cost of the equipment is displayed. In this methodology, design parameters, such as induction, number of turns (volts/turn), current density and the aspect ratio of coil form are varied in order to find the best transformer design. Simulation tools of Computational Fluid Dynamics (CFD) using Finite Volume Method (FVM) were applied aiming at proposing innovations to the cooler system taking into account the characteristics of viscosity of the vegetable oil. As result, was developed a prototype unit of 75kVA, voltage class of 15kV, primary voltages of 13,800/13,200/12,600V and secondary voltages of 380/220V, amorphous core, aluminum wires and vegetable insulating oil.

FEM Aided Design of Distribution Transformer

Computer aided procedure for design of distribution transformer is implemented on transformer type ETN 50-1-/0.4 a product of “EMO” company. All transformer parameters are calculated in Matlab as well as operational characteristics of voltage variation and efficiency factor at different type of loads and variation of secondary voltage for different secondary currents. The obtained results are compared to the experimental data from the producer. Finite Element Method (FEM) is implemented for calculation of distribution of magnetic flux density in transformer cross section for different operating regimes: no-load and rated load. FEM calculations are based on data obtained from transformer design. They enable electromagnetic processes inside the machine to be analyzed and accurate calculation of magnetic flux density to be done.

A comparative analysis of multi-objective and multialgorithm approaches for the optimal design of distribution transformers

This paper presents the sizing of three phase transformer using four intelligentalgorithms namely geometric programming, genetic algorithm, simulated annealing,and particle swam optimization. Four independent objective functions and eightconstraints were used. The comparative analysis carried out on the results obtainedfrom these intelligent algorithms shows that all the outputs from the intelligentalgorithms are the same. The fastness of results shows that geometric programmingis the fastest, while genetic algorithm, simulated annealing, and particle swamoptimization followed in that order. The output results from the cost objective functionwere compared with the results obtained by Masood (2012) and it showed that moneywas saved in the following order, 6.4%, 16.32%, 10.63% and 16.79% respectively forgeometric programming, genetic algorithm, simulated annealing, and particle swamoptimization.

Evaluation of distribution transformer banks in electric power systems

SUMMARY 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. Copyright © 2011 John Wiley & Sons, Ltd.

Power Transformer No-Load Loss Prediction with FEM Modeling and Building Factor Optimization

Estimation of power transformer no-load loss is a critical issue in the design of distribution transformers. Any deviation in estimation of the core losses during the design stage can lead to a financial penalty for the transformer manufacturer. In this paper an effective and novel method is proposed to determine all components of the iron core losses applying a combination of the empirical and numerical techniques. In this method at the first stage all computable components of the core losses are calculated, using Finite Element Method (FEM) modeling and analysis of the transformer iron core. This method takes into account magnetic sheets anisotropy, joint losses and stacking holes. Next, a Quadratic Programming (QP) optimization technique is employed to estimate the incomputable components of the core losses. This method provides a chance for improvement of the core loss estimation over the time when more measured data become available. The optimization process handles the singular deviations caused by different manufacturing machineries and labor during the transformer manufacturing and overhaul process. Therefore, application of this method enables different companies to obtain different results for the same designs and materials employed, using their historical data. Effectiveness of this method is verified by inspection of 54 full size distribution transformer measurement data.

Object-Oriented Knowledge-Based System for Distribution Transformer Design

The first stage in any machine design process involves a substantial heuristic exercise to select the machine best suited to a set of specifications. The second stage obtains the dimensions of a selected machine and a design that satisfies specifications. The final stage usually involves optimization and the finite-element method. We present an object-oriented knowledge-based system for distribution transformer design with the first two stages fully automated. We describe the rationale for the system, the architectural design procedure, and the approach taken in constructing the system for practical applications.

Design of distribution transformers based on a knowledge-based system and 2D finite elements

This paper presents the development of a hybrid system for the design of distribution transformers. It is based on a knowledge-based system (KBS) and two-dimensional (2D) finite-element (FE) models, which are used to compute the electromagnetic fields within the transformer. A KBS is a software product based on established artificial intelligence techniques that has been successfully applied in many areas, whereas the FE method is a sound numerical technique for solving partial differential equations. Both methods are combined to offer transformer designers a computational tool for designing distribution transformers. First order elements are employed in two FE models, an axi-symmetric one is used to compute leakage reactance and eddy losses in transformer windings and a 2D cartesian model is used to calculate the iron loss and magnetizing current. The KBS mimics the designers experience through the representation of heuristic, procedural and graphical knowledge. The proposed design system is applied to the design of a 1500 kVA, 13.2 kV–220 V, delta-star, oil-filled distribution transformer.

An intelligent assistant for designing distribution transformers

Distribution transformers constitute the most numerous and varied types of transformers used on the electricity supply network. Its design is normally based on traditional calculations and empirical knowledge, which is on the hands of experimented design engineers. Consequently, the computer assisted design of distribution transformers is a particular need for manufacturers, who try to save experimented engineering-design man-hours, increase design capacity, reduce the delivery cycle and optimize the use of materials. In this paper, an intelligent design assistant (IDA) is proposed that consists in a knowledge-based system that combines object-oriented, rule-based, and procedural programming techniques to assist in the design of power distribution transformers. It was developed by a process of interviews, knowledge engineering and coupled with an assessment of the current state of the technology to bridge the gap between practice and theory. To illustrate the validation of the IDA, the results achieved by a novice engineer to design a 1500kVA, 13.2/0.22kV distribution transformer are presented.

An alternative evaluation of distribution transformers to achieve the lowest TOC

The 65 degrees C rise rating of a distribution transformer is a thermal life rating of its insulation system, not the best efficiency condition. Total owning cost (TOC) is reference at 85 degrees C which is based on a 20 degrees C ambient plus a 65 degrees C rise. For better efficiency, a transformer should be operated at a lower temperature. Transformer design programs calculate a design for the lowest TOC at the 85 degrees C reference temperature. These programs do not calculate a design for the lowest possible temperature rise or lowest TOC regardless of reference temperature. As a consequence, the lowest TOC is not realized. An evaluation method is proposed that will provide the user with a distribution transformer design which has a lower operating temperature rise, thus improving both the transformer's efficiency and the customer's TOC.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design and realization of amorphous material transformers

The paper deals with the design, realization, and tests of two singlephase distribution transformer samples built using amorphous magnetic material (POWERCORE®) for one and high permeability magnetic materials (type M0-H30) for the other. Some preliminary considerations from the performance and cost point of view have been pointed out, taking into account the capitalization costs due to the iron and copper losses. The work described in this paper is to be considered as a first step in order to acquire both knowledge related to the use of amorphous material and basic data to develop energy saving considerations and optimum design of distribution transformers. In the paper complete experimental results and full details about the construction criteria are reported.

Impulse testing of distribution transformers under load

The paper describes a new functional test procedure for evaluating the impulse strength of distribution transformers under service-related conditions, including rated voltage, different current levels, and the effect of precipitation. The test procedure was applied to a representative sample of 54 commercial distribution transformers having a 15kV class insulation system. Specimen transformers used in this project were taken from utility stockpiles. The results reported here showed a significant decrease of impulse strength both with increasing load current and with aging under laboratory conditions. The paper thus presents new information pertaining to transformer failures and may contribute to improved distribution transformer design and surge protection practices.