Type Distribution Transformer Research Articles

Cost optimization of oil type distribution transformer using multi-objective genetic algorithm

The demand for electrical energy is increasing day by day with the development of technology in the world. Distributing electric energy to all regions that need energy is a principal issue, and this necessitates the use of transformers to convert the voltage to the desired level. Accordingly, the use of transformers, one of the electrical devices converting AC voltage level at a defined frequency has grown significantly. In this study, design parameters of a 25 kVA, 33/0.4 kV, Yzn11, oil-type distribution transformer are optimized using the Multi-Objective Genetic Algorithm (MOGA) technique by decreasing the weight of the significant materials and manufacturing cost. Electromagnetic analysis of the transformer is performed with ANSYS Maxwell based on the design results obtained from the optimization study for validation of the method. The experimental design parameters are also compared with the optimization results. It is observed that optimum results are achieved by using the proposed approach.

Study of Transformer Harmonic Loss Characteristic in Distribution Network Based on Field-Circuit Coupling Method

One of the primary causes of additional losses in dry-type distribution transformers is harmonic disturbances in the distribution network. It is critical to investigate the change law of trans-former losses under harmonic conditions. The effect of harmonics on transformer core losses and winding losses is first investigated in this paper. The field-circuit coupling method is then used to create a finite element model of a three-phase phase dry type distribution transformer. Finally, the relationship between core loss and harmonic voltage, winding loss and harmonic current is calculated and analyzed for each harmonic frequency. The AC resistance factor model is found to be more accurate than the conventional model in calculating transformer harmonic winding losses. This paper’s findings have significant theoretical implications for the analysis of harmonic losses and loss reduction in distribution networks.

Multiobjective Optimization Techniques Applied to Three-Phase Transformers Designs

The aim of this research is to present the studies carried out to design three-phase core type distribution transformers, with the aid of optimization techniques. The minimization of losses is presented in two steps, first through the use of a mono-objective function, and second with the use of multi-objective function to minimize losses and the total mass of the active part of the transformer. The algorithms used are: Differential Evolution and Particle Swarm Optimization, their performances are compared through the results obtained. The main project parameters, such as core dimensions, total losses, no load current and the energizing current are estimated analytically through OCTAVE software. The analysis of magnetic flux density in the core is simulated using the Finite Element Method. Multiobjective optimization allows working with two or more conflicting objectives, and at each iteration, it stores the various non-dominant Pareto Front solutions, helping designers to choose the solution that best meets their needs. The results obtained with the mono-objective and multiobjective optimization techniques were interesting to minimize the losses and/or cost of the project

Thermal Analysis of Natural Cooling Type Distribution Transformer Retrofilled With Natural Ester Oil

Retrofilling distribution transformers with natural ester has attracted increasing interest among the utilities. Many retrofilled transformers have layered winding structures and natural cooling mode. The thermal performance of such types of transformers has not been thoroughly studied. To ensure the temperature rise in a layered winding type retrofilled transformer complying with IEC-60076-14, it is necessary to analyze the temperature distribution inside the transformer. In this article, the temperature distribution of a layered winding natural cooling type distribution transformer is investigated under a retrofilling scenario. The computational fluid dynamics (CFD) analysis is performed to compare the cooling performance of the transformer filled with mineral oil and that of the transformer filled with natural ester oil. The temperature distribution along the height of the transformer winding is investigated through fiber optic sensors. Moreover, the dimensional analysis method is applied to understand the influence of several parameters (oil characteristics and dimension of cooling ducts) on temperature distribution and hot spot factor. The findings of this article can support the decision-making of retrofilling of layered winding natural cooling mode transformers.

외철형 배전용 변압기의 손실 감소를 위한 철심 최적설계

외철형 배전용 변압기의 손실 감소를 위한 철심 최적설계

Evaluation and improvement of the main insulation structure of 33kV distribution transformer based on FEM

<span>This paper introduces a 2-D FE model to analyze the electric field distribution to evaluate and improve the insulation structure of the 250kVA, 33/0.4kV wound core type distribution transformer using the ANSYS 17.2 by implementing APDL program. The dielectric lighting impulse test was simulated in order to test the presented transformer model according to the IEC67006-3 standard, the assessment process is based on determining the electric stresses and compare it with the maximum permissible value of electric field intensity. Three proposed FE model as an improvement to the insulation structure of the transformer included reducing the insulation distances, changing the materials type, and mix both of them. The results obtained from the FE solution were compared with those of the real test, and presented in form of contours, curves, and vectors. The results obtained from the presented model can be further treated as a reference data in the design process.</span>

FEM Application for Evaluating and Improving the Insulation System of the 33kV Wound-Core Type Distribution Transformer

This paper presents a 2-D & 3-D FE model of 250kVA, 33/0.416 kV wound core type distribution transformer, simulated using ANSYS 17.2 software in order to evaluate the insulation system via dielectric strength under power frequency and induced withstand tests and using two types of analysis, time-harmonic analysis to simulate the dielectric tests, and electro-static analysis to calculate the capacitance matrix. The assessment is based on the maximum allowable electric field intensity. the obtained results were compared with those of the real test, and the values of electric stress were less than the maximum allowable values. also, improvements to the presented model were applied following the transformer assessment. The improvement to the transformer insulation structure was done using three suggested finite element models included reduction and changing the materials type. the results were reviewed in form of contour plots, vector plots, and curves.

Comparing life cycle cost and environmental impact optimizations of a low voltage dry type distribution transformer

PurposeLife cycle analysis (LCA) is more and more used in the context of electromagnetic product design. But it is often used to check a design solution regarding environmental impacts after technical and economical choices. This paper aims to investigate life cycle impact optimization (LCIO) and compare it with the classical life cycle cost optimization (LCCO).Design/methodology/approachFirst, a model of a dry-type transformer using different materials for windings and the magnetic core is presented. LCCO, which is a mixed continuous-discrete, multi-objective technico-economic optimization, is done using both deterministic and genetic algorithms. LCCO results and optimization performances are analyzed, and an LCA is presented for a set of optimal solutions. The final part is dedicated to LCIO, where the paper shows that these optimal solutions are close to those obtained with LCCO.FindingsThis paper investigated LCIO using an environmental impacts model that has been introduced in the optimization framework Component Architecture for the Design of Engineering Systems. The paper shows how a mixed continuous-discrete, multi-objective technico-economic optimization can be done using an efficient deterministic optimization algorithm such as Sequential Quadratic Programming. Thanks to the technico-economic-environmental model and the efficient optimization algorithm, both LCCO and LCIO were performed separately and together. It has been shown that optimal solutions are similar, leading to the conclusion that only one modeling is required (economic or environmental) but on the life cycle.Originality/valueThe classical sequential methodology of design is improved here by the use of a model of calculation of the environmental impacts allowing the optimization. This original optimization allowed the authors to show that an analysis of the life cycle from an economic point of view or from an environmental point of view led to quasi-equivalent technical solutions. The key is to take into account the life cycle of the product.

Aging assesment of transformer pressboard insulation by micro-strip ring resonator at GHz frequencies

Condition assessment of insulation is widely used to identify the state of aging of power transformers. Traditionally, condition assessment is done using dielectric response measurements conducted at low frequencies. However, due to long testing time required for these methods, attention has now been paid towards measurements at microwave (above 1 GHz) frequencies. In this paper, we establish a correlation between dielectric properties and the state of aging of transformer pressboard samples. This is useful as it paves way to develop techniques to assess the state of aging by measuring dielectric properties at high frequencies. Dielectric measurements are made by using a microstrip ring resonator. The state of aging is determined by measuring the tensile index. Tests were carried out on dry and wet oil-impregnated pressboard samples thermally aged at laboratory conditions for durations up to 45 days. The results were compared with field aged samples collected from a 33 kV sealed type distribution transformer of 18 years in service. It was found that the permittivity values had a good correlation with respective tensile index values whereas loss tangent values showed limited correlation for both dry and wet samples. The results of field aged samples matched well with the established correlation curves. It can be concluded that the permittivity of pressboard samples estimated from the ring resonator can be effectively used to evaluate the state of aging of transformer insulation.

Weight Comparison of Oil and Dry Type Distribution Transformers

Weight Comparison of Oil and Dry Type Distribution Transformers

Optimal Design of Transformer using Tournament Selection based Elitist Genetic Algorithms

Transformers are vital components of power systems and its design requires reliable and rigorous solution methods. Optimal design of transformer involves determination of design variables to optimize a particular objective, satisfying a set of constraints. This paper addresses the problem of optimal transformer design of a three phase core type distribution transformer using Elitist Genetic Algorithms. Two MATLAB programs have been developed to accomplish the task. The first program implements unconstrained minimization of the following four objective functions: total active part cost, total losses, percentage impedance and transformer tank volume using GA; while second program considers both GA and conventional method to minimize the active part cost while simultaneously satisfying BEE (Bureau of Energy Efficiency) standards and constraints. After performing exhaustive analysis and comparing the results with those obtained by conventional method it is concluded that the results obtained by Tournament Selection based Elitist Genetic Algorithm is near optimum. A design example on a 100 kVA, three phase core type distribution transformer using GA and conventional method is presented for illustration.

Comparison of assumptions in computation of short circuit forces in transformers

This paper describes the modeling of shell type distribution transformers with varying degrees of complexity. Results from several types of studies are reported and used to evaluate the effectiveness of FEA methods for resolving the forces exerted on the coils of a single-phase shell form transformer. The sensitivity of these methods to the very small changes in configuration due to manufacturing tolerances or operation are investigated. Several types of analysis were performed and compared to determine the best approach for design or failure analysis.