INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 DESIGN OF HIGH VOLTAGE USING FINITE ELEMENT METHOD M.Leela Nivashini, K.Madhumitha, S.Sindhu, Dr.R.V.Maheswari

Abstract—: A transformer is a static device that is mainly used for stepping up and down the voltage level. The Power transformer is a kind of transformer that is used to transfer electrical energy in any part of the electrical circuit between the generator and the distribution primary circuits. These area unit employed in distribution systems to interface intensify and step down voltages. The transformer is important in transmission and distribution hence their testing is also essentially equal. The cost of a high is too high and also unavoidable equipment in that domain, hence it has to be designed properly before implementation in real-time. Simulating the transformer with the designed parameters will give the same results as in the real model. So it is easy for analyzing the EF distribution and calculating the losses and that can be easily avoided while implementing in real-time. The simulation of a three-phase 11/0.4 KV power transformer using the Finite Element Method is carried out in this project.

Index Terms— Power transformer, Losses ——————————  ——————————

1 INTRODUCTION Electrical device could be a passive device that transfers 2 POWER TRANSFORMER electricity between 2 or a lot of circuits. Current in the primary winding produces magnetic flux, this in turn creates variable 2.1 DESCRIPTION EMF in the secondary winding of the same electrical device. Using inductive coupling method, energy is transfer from one Without any metallic contact electrical energy is transmitted circuit to another in power electrical devices. Power electrical between two coils as shown in Figure.1. By faradays law of devices differ from different transformer sorts in this they're electromagnetic induction induced voltage has impact on the designed in such a way that they go with regulative coil in accordance to the dynamic magnetic flux encircled by necessities for mains power interfacing, performing at mains the coil. Transformers are used for step up and step down in voltages and comparatively high currents. The foremost the AC voltage in electrical power applications and also for necessary specification of an electrical device is its primary to coupling the various stages in signal processing circuits. secondary winding galvanic isolation which is specified in Transformers have become essential for the distribution, terms of kV [3]. This can be a basic safety side in protective transmission, and utilization of alternating current electric against deadly earth fault conditions. Power transformers power, due to the invention of the primary constant potential in usually have one mains side winding and one or more field electrical device [2]. Wide varieties of electrical device styles windings. The field coil could also be introduced at totally is confront in electronic and electrical power applications. different points to yield multiple voltage outputs. An influence Transformers point size from RF transformers but a cc in electrical device works in accordance with Faradays Law of volume, to unit’s advisement many tons wont to interconnect Electromagnetic Induction. A transformer’s secondary voltage the ability grid. is capable of producing abundant magnetic flux in the circuit is caused by the AC flowing within the primary. The dynamic flux produced by the AC couples the secondary coil through a standard core [4]. The voltage quantitative relation is adore the winding flip quantitative relation. Transformers square measure extraordinarily economical once operational at intervals their style specifications. The core sort is a very important thought. Typical power electrical device provides embody laminated core, semi-solid and solid. Laminations are used to resist the eddy currents flowing within the core that in turn cause loss of potency [5]. Whenever the core is saturated or the windings current rating is exceeded the output current is Fig. 1. Transformer circuit. specified to the maximum. The mounting choices for square measure consist of chassis mount, DIN rail, wall mount and ———————————————— PCB mount. Terminations consist of solder lugs, wire leads  Ms.M.Leela Nivashini is studying final year Electrical and and terminal blocks. Galvanic isolation range is from 0.5kV Electronics Engineering in National Engineering College, India, E- and 5kV. mail:  Ms.K.Madhumitha is studying final year Electrical and Electronics Engineering in National Engineering College, India, E-mail: 2.2 TRANSFORMER CONSTRUCTION  Ms.S.Sindhu is studying final year Electrical and Electronics In a transformer electrical windings are coupled together by a Engineering in National Engineering College, India, E-mail: magnetic field. The coupling is increases with increase in force  Dr.R.V.Maheswari is currently working as a Professor in department of Electrical and Electronics Engineering in National Engineering of magnetic core in special-purpose transformers. College, India. Transformers are not built in a way that they are with the 5351 IJSTR©2020 www.ijstr.org INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 primary coil on one arm and the secondary coil on the other construction In order to reduce the leakage flux in the primary arm. Primary winding induces the magnetic flux when an AC and secondary winding, shell sorts are used since cross voltage is supplied, which in turn induces voltage in the sectional space between two limbs are doubled. Shell sort has secondary. The secondary winding induces a sinusoidal the advantage that, before reaching the center coil the voltage whenever the flux is curve. The primary is connected magnetic flux flows in two ways from external to coils on to the source (generator), and the secondary is connected to primary and secondary windings. In this type of transformer the load. High-voltage or low-tension facet is available. The construction the magnetic flux circulating the outer limbs of magnetizing current is minimized by constructing core with low is equal to Φ/2. Whenever the magnetic flux induced in a reluctance material [6]. The core is made of laminations in closed path the magnetic core losses is decreases and overall order to reduce losses, the rated frequency of the potential of the transformer increases. transformer is inversely proportional to thickness of the core. The lamination thickness squared is directly proportional to 2.4 WINDING Eddy current losses. Thus, the eddy current losses are Depending upon applying of electrical field, electrical current reduced to 75% by halving the thickness; however, the cost of passes through all the conductors of the windings and each the core decreases with increasing lamination thickness [7]. turns are insulated around each other. The magnetic wire coil The cost of building the core must be compensating against wound is used for small transformer with low current and low the cost of the losses. Silicon steel laminations are used for voltage applications. Oil-impregnated paper and blocks of 60 Hz operation, with thicknesses of 0.010″ to 0.020”. The pressboard used for wind larger power transformers wrapped wound ribbon is used for very high-frequency operation. The with copper strips. In order to reduce the skin effect and losses laminations must be insulated from each other for the flow of in high frequencies transformer litz wires are used for winding. eddy current [8]. The insulation may be nothing more than the Even at low power frequencies power transformers with oxidation on the surface of the lamination. The flux density will multiple-stranded conductors used in non-uniform distribution be higher when the core is insulated than iron insulation. and high current applications. Windings are equally insulated These factors are calculated as stacking factor. Stacking with the single strand so that entire portion is occupies by factor is used to measure the percentage of cross sectional different relative positions in the conductor. Each and every area of the iron. The stacking factor is ranges above 0.9 for 60 strands is equalizes by transposition in order to reduce the Hz operation. Stacking factor decreases with decrease in eddy current losses in the winding. In manufacturing process lamination thickness. stranded conductors are more flexible than a solid conductor.

2.3 TRANSFORMER CORE 2.5 WORKING PRINCIPLE AND OPERATION Transformer is an electrical device that steps up or steps down The main operation principle of a transformer is coefficient the electrical voltage. It consists of two windings i.e., primary of mutual induction between two circuits that is joined by a and secondary windings are wound round the central magnetic flux. A basic transformer consists of primary and laminated steel core. The two most typical and basic type secondary windings which are electrically isolated but of core construction in transformer are the closed-core and magnetically connected through a path of reluctance. The shell type core. In Closed-core type, the primary and core is made up of laminated sheets in order to eliminate o secondary windings are wound outside and surround the reduce the eddy current loss in the transformer. These core ring. In Shell type core, the secondary windings pass laminated sheets are joined through the staggered joints in inside the steel magnetic circuit (core) which forms a shell order to avoid the pursuance of normal air gap right around the windings as shown in Fig.2. through the cross sections. These staggering joints are said to be 'imbricated'. Both the coils have high mutual inductance. If one of these coils is connected to the source of alternating voltage, a mutual EMF will be induced in another coil. This can be explained by the Faradays law of mutual induction.

3 DESIGN OF TRANSFORMER 3.1 DESIGN PARAMETERS IN TRANSFORMER These parameters are split into seven types Fig. 2. Basic core construction  Description variables (e.g., rated power, rated low voltage (LV) and high voltage (HV), frequency, LV The magnetic flux linking the primary and secondary and HV connection). windings travel through the core with no losses. In  Special variables (core stacking factor, the mass transformer magnetic circuit primary and secondary windings density of materials used). are wound around each limbs of electrical devices as shown  Default variables (e.g., LV and HV taps, guaranteed a above. The coils arranges in such a way that half of the first no-load loss, load loss, and impedance voltage). winding and half of the secondary winding are placed one  Cost variables (e.g. Unit cost of Material). above the another in concentric manner so that the Various. variables (e.g. No’s of HV & LV Ducts) magnetic lines of forcers are equal in both the winding .  Leakage flux is nothing but the small amount of magnetic  Conductor cross section calculation. Variables (HV lines of force flows outside the core in electrical device /LV Cross section). 5352 IJSTR©2020 www.ijstr.org INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616

 Design variables. (E.g. Leg center, Window height, LV • Gauss’ Law for Magnetism 훁.푩=ퟎ turns)”. • Faraday’s Law of Induction 훁 ×푬= −흏푩/흏풕 • Amperes’ Law 훁 ×푯=푱 + 흏푫/흏풕 3.2 STEPS FOR DESIGNING TRANSFORMER a. Calculation of Number of Turn With this software package, the non-linear, transient motion of Based on kVA rating EMF per turns is calculated. So, EMF per electromechanical devices can be characterized and their turns is calculated using an equation effects can be predicted. It is widely used in industries as a

EMF per turn, 퐸 = 푘√Q simulation technology in performance analysis of the Where Q=Power rating electromechanical system and hence building a prototype. The numbers of primary and secondary turns are calculated as follows, 4.2 ANSYS RMXPRT No of turns in primary, 푇 = 푉 /퐸 (RMxprt) Rotating Machine Expert is a template-based No of turns in secondary, 푇 = 푉 /((√3 ∗ 퐸 ) design tool that help to easily evaluate the design trades- Where, 푉 ,푉 is voltage in primary and secondary winding off early in the process. It enables the customized respectively. designing of the machines to meet the demand of higher efficiency. The main advantage of this tool is that it has the b. Core Design ability to automatically generate the entire design set-up in Core design includes the calculation of area, diameter, and 2D/3D including the geometry, materials and also several steps of the core. This design is based on frequency, boundary conditions. The set up includes the appropriate flux density and EMF per turns. symmetries and excitations with coupling circuit topology Flux in the core, ɸ = 퐸 /(4.44 ∗ 푓) for electromagnetic transient analysis. The major Net iron area, 퐴 = ɸ /B advantages of using this ANSYS Maxwell software are: • Industry Leading Low-Frequency Electromagnetic c. Winding Design Field Simulation. There are two types of winding designs: (i) HV winding. • High-Performance Design Delivery. Design and (ii) LV winding design. To design a winding, rated • High Fidelity, Model-Based Design. current, cross-sectional area, number of a disc, tapping disc, turns per. disc, radial depth, axially shrunk height, and shrunk 2-D/3-D vector hysteresis modeling in ANSYS Maxwell is height, inner and outer diameter is calculated. Some standard applicable for each soft and arduous magnetic materials. constant values are required to design winding. Maxwell second may be a superior interactive package that uses finite component analysis (FEA) to resolve electrical, Secondary phase current,I = 푄/(3 ∗ V ) magneto static, eddy current, and transient issues. There Area of secondary conductor, A = I /δ are six solvers available in Maxwell 2D. They are: Axial depth of LV winding, • Electrostatic. L = turns ∗ axial depth of conductor • AC Conduction Electric Fields. Radial depth of LV winding, • DC Conduction. B = No. of layers ∗ Radial depth of conductor • Magneto static. Resistance of primary winding= (푇 *ρ*length of primary • Eddy Current Magnetic Fields. winding)/ (A ) • Transient Magnetic. Similarly calculation is being done for the HV winding. 4.3 SYSTEM REQUIREMENTS 4 MODELLING OF TRANSFORMER USING All the simulations were done using ANSYS Workbench and FINITE ELEMENT METHOD the last version of Maxwell, 19.2 and a personal computer with 4.1 ANSYS MAXWELL the following characteristics. ANSYS, Inc. is a yank Computer-aided engineering package • CPU: Intel Core i5 6th generation. developer that publishes engineering analysis package across • RAM: 8GB a spread of disciplines like finite part analysis, structural • Hard Disk Space: 1 TB analysis, procedure fluid dynamics, explicit/implicit ways, and warmth transfer. ANSYS Maxwell as a superior, low-frequency 4.4 FINITE ELEMENT METHOD (FEM) magnetic force field simulation interactive package. ANSYS To resolve the issues of engineering and mathematical Maxwell uses finite part analysis (FEA) method to resolve physics the numerical technique such as finite part magnetic force issues by resolution Maxwell's equations in an technique (FEM) plays a vital role. The drawback of exceedingly finite region of space with appropriate boundary structural analysis, heat transfer, fluid flow, mass transport, and user-specified initial conditions. Maxwell uses the correct and magnetism potential. In partial differential equations finite part technique to resolve static, frequency-domain, and the solutions for boundary values are met out by analytical time-varying electromagnetic and electric fields. solution. The subdivision of a full domain into less The magnetic force field are given by James Clerk Maxwell as complicated components has many benefits. physical equations which are as follows: • complex geometry representation

Insertion of dissimilar material properties • Gauss’ Law for Electricity 훁.푫=풑 • 5353 IJSTR©2020 www.ijstr.org INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616

• Representation of the total solution effective when compared to real time experimental set up. • The capture of local effects. This 3-D model analysis helps to verify the losses occurs in Known as Finite Element Analysis (FEA) is suitable for real time. practical application, to understood FEM method [15]. For 6 RESULT AND DISCUSSION activity engineering analysis FEA is used as process tool The three-phase power transformer with the rating of for engineering analysis. It includes the employment of 11/0.4 kV was designed by considering certain parameters mesh generation techniques for dividing a posh drawback such as type of the material used for core, the lamination into little parts, additionally because the use of package on the core, window dimensions, the type of the winding program coded with FEM rule. FEA is a best choice for such as helical, disc and cylindrical, the material used for analyzing problems in complicated domains, when the winding, number of turns in primary and secondary domain changes or required preciseness varies over the winding, the resistance in the windings, the frequency domain, or the answer will lacks its smoothness. range for operation etc., The designed transformer model is simulated in the ANSYS software. 5 EXPERIMENTAL RESULTS 5.1THEORETICALLY DESIGNED PARAMETERS 7 CONCLUSION The 3 phase power transformer is experimentally tested with A simulation is an approximate imitation of the operation of the help of these design parameters are given in Table 5.1 a process or system that represents its operation over time. This is used for obtaining the optimized model. In this Table 5.1 Designed parameter project, three-phase power transformer was designed by the conventional formulas and simulated the model using PARAMETER VALUE ANSYS software. Frequency 50Hz Rated voltage 11/0.44 KV REFERENCES Rated current 315/7860 A [1] https://www.instructables.com/id/Three-Phase Number of turns 400/16 Transformer-Design Using-Ansys-Maxwell/ Design of Three phase transformer using ANSYS. EMF per turn 9.607 Volt/turn [2] Design Methodology of Power Transformer CHAPTER 4: Area of iron core 0.0255 푚 DESIGNMETHODOLOGY OF POWER TRANSFORMER Number of primary turns per phase 1145 [3] Dawood " A new method for the calculation of Number of secondary turns per phase 25 leakage reactance in power transformers", J. Elect. Eng. Technol., vol. 12, no. 5, pp. 1883-1990, 2017. Resistance of primary winding 1876 Ω [4] Gäfvert, Adeen, Tapper, Ghasemi, Jönsson, Resistance of secondary winding 49 Ω "Dielectric Spectroscopy in Time and Frequency Domain Applied to Diagnostics of Power The above mentioned design parameter values of 3 phase Transformers", Proc. Of the 6th ICPADM, Xi' power transformer are derived and calculated using an, China, 2000. appropriate formulae. [5] Jamali, Mirzaie and Asghar Gholamian, “Calculation and analysis of transformer Inrush current based on parameters of transformer and operating conditions”, 5.2 SIMULATION OBTAINED BY FINITE ELEMENT METHOD Electronics and Electrical Engineering – Kaunas: Technological, no. 3 (109). , pp. 17-20-2011. USING ANSYS SOFTWARE [6] Kashtiban, "Finite Element Calculation of Winding Using the values form Table 5.1, the three phase power Type Effect on Leakage Flux in Single Phase Shell Type transformer was designed and stimulated by Finite Element Transformers", Proceedings of the 5th WSEAS Method using ANSYS software. International Conference on Applications of Electrical Engineering, pp. 39-43, March 12-14, 2006. [7] Susa, “Dynamic thermal modeling of power transformers”, Ph.D. dissertation, Dept. of Electrical and Communications Eng., Helsinki Univ. of Technology, 2005. [8] Werelius " Diagnosis of Medium Voltage XLPE Cables by High Voltage Dielectric Spectroscopy" paper presented at ICSD 1998. [9] Sarac V. Faculty of Electrical Engineering, University “Goce Delcev”, R. Macedonia,” fem 2d and 3d design of transformer for core losses computation” Industry 4.0 Vol. 2 , Issue 3, pg.(s) 119-122-2017. Fig. 3. Basic core construction [10] Meethaq Talib Jabbar, "Electromagnetic Modeling and Design of 11/0.4 ", M.Sc. Thesis, The 3-D model is computed in ANSYS with the designed University of Technology, 2013. values shown in the Fig .3. This 3-D stimulated model is cost 5354 IJSTR©2020 www.ijstr.org INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616

[11] Kassim, R. Hameed. "Analysis of Short-Circuit Forces in Windings of Shell-Type Wound Core Distribution Transformer Using Finite Element Method Ph.D. Thesis, University of Technology, 2007. [12] David Ribbenfjard, "Electromagnetic Transformer Modeling Including the Ferromagnetic Core'', Ph.D. Thesis, Stockholm, Sweden, 2012. [13] Waleed A. Baddai, Two-Dimensional Nonlinear Finite Element Modeling Of A Single Phase Transformer", M.Sc. Thesis, University of Technology, 2004. [14] Hernández1,I. J. M. Cañedo, J. C. Olivares-Galván and P.S.Georgilakis, Electromagnetic Analysis and Comparison of Conventional-Wound Cores and Octagonal-Wound Cores of Distribution Transformers”, Materials Science Forum Vol. 670 pp 477-486, Vol.4, No.2, pp. 155-164,Switzerland, 2011. [15] L.I. Sakhano, O.I. Skhano, S.d. Dubitskiy, V.V. Valkov, and R.V. Zaryvaev: Using the finite element method for calculating transformers for resistance welding machines, Welding International, vol. 31. No. 1, 2017, pp. 58-63.

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