International Journal of Informative & Futuristic Research ... · x 14 %- 17 % of the transmission line voltage is developed across the nearest insulator to the line-end. The voltage

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Published On: 31ST May, 2016

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International Journal of Informative & Futuristic Research ISSN: 2347-1697

Volume 3 Issue 9 May 2016 Research Paper

Abstract

Computation of potential and electrical field strength along the insulator strings is an important aspect for their designs. Similar with porcelain insulator strings, the axial potential distribution of composite insulator strings is non-uniform. Based on the characteristics of capacitive electric field distribution of composite insulators, this paper presents a new measure to improve electric field distribution based Ceramic insulators are widely used in power transmission lines to provide mechanical support for High voltage conductors in addition to withstand electrical stresses. As a result of lightning, switching or temporary over voltages that could initiate flashover under worst weather conditions, and to operate within interference limits. Given that the useful life in service of the individual insulator elements making up the insulator strings is hard to predict, they must be verified periodically to ensure that adequate line reliability is maintained at all times Due to deficiency of electric field data for the existing string configuration, utilities are forced to replace the discs

Simulation Of Potential And Electric Field

Distribution For Different Parts Of Insulator

Using Finite Element Method Paper ID IJIFR/V3/ E9/ 056 Page No. 3448-3454 Subject Area

Electrical &

Electronics Engg.

KeyWords Insulator, CATIA, Hypermesh, ANSYS, FEM

1st Sulthan Mohyuddin

Associate Professor

Department of Electrical and Electronics Engineering

Srinivas Institute of Technology

Valachil, Mangalore-Karnataka

2nd Harshith K

Assistant Professor

Department of Electrical and Electronics Engineering


Valachil, Mangalore-Karnataka

3rd Nazma S Assistant Professor

Department of Electronics & Comm. Engineering


Valachil, Mangalore-Karnataka 4th Kripa K B

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3449

ISSN: 2347-1697

International Journal of Informative & Futuristic Research (IJIFR)

Volume - 3, Issue -9, May 2016

Continuous 33rd Edition, Page No.: 3448-3454

Sulthan Mohyuddin, Harshith K, Nazma S, Kripa K B:: Simulation Of Potential And Electric Field Distribution For Different Parts Of Insulator Using Finite Element Method

which may not be essentially required. Hence, effort is made in the present work to simulate the potential and electric field along the normal and with faults induced discs. This study is concerned with the voltage and the electric field distribution on a ceramic disc insulator of insulator type suspension strings composed of cap and pin type porcelain insulators. It’s one of the main structure utilize for the better operation of insulator. Finite Element Method based software, CATIA and HYPERMESH, was used three dimensional modeling and simulations.

1. INTRODUCTION

Control of electrical field distribution within and around high voltage equipment is one of

the basic aspects of the design of such equipment. Audible noise, radio noise, partial

discharges and corona discharges are some of the possible results of high level electrical

fields. Modern society exclusively depends on the electrical power for industrial,

commercial, agricultural, domestic and social purposes. The electrical energy is generated

mainly at the hydro, thermal and nuclear power stations. Due to various reasons, the

generating stations and the load centers are geographically far off, which necessitates

transmission of bulk power over long distances. This important task at present is mostly

performed by overhead power transmission lines. Currently, underground transmission is

also employed however; capacitive charging current of the cable limits its application to

shorter distances. In a dry and clean state, the voltage distribution of a composite insulator

string is characterized by a capacitive distribution. According to Kirchhoff’s law, if a composite insulator circuit is placed in a series with capacitors, resistors, or inductors, the

voltage of the composite insulator can be assumed to be significantly improved.

2. IDENTIFICATION OF NUMERICAL TECHNIQUES

Due to the sensitivity of insulating materials to electric field, accurate determination of

electric field is necessary while designing and diagnostics of high voltage apparatus.

Various numerical methods have been employed over the years for the computation of the

electric potential and field along the insulator string. Basically there are two methods,

Domain based methods and Boundary based methods. Finite Difference Method (FDM)

and Finite Element Method comes under Domain based methods, and Boundary based

methods includes Boundary Element Method (BEM), Charge Simulation Method (CSM)

and Surface Charge Simulation Method (SCSM).

3. DESCRIPTION OF EXISTING PROBLEMS

Although the EFPD along the ceramic insulators has been widely studied for a long time,

the results of these studies cannot be applied directly to the real power line insulators. The

limitations of the previous studies are: The analysis of the EFPD along ceramic insulators

usually assumes single phase energization. However, a real power line means three phase

energization, and the presence of the other two phases may have some influence on the

EFPD along a ceramic insulator.

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4. LAPLACE EQUATION AND MODEL

Calculation of electric fields requires solution of Laplace's eqn. and Poisson’s equation eqn. with boundary conditions satisfied. This can be done either by analytical or numerical

methods. ∇ � = −�/� (1)

……………. ∇ � = (2)

………

In eqns. the operator ∇ is called the laplacian and is a vector with properties

∇. ∇ = ∇ = ∂2∂x2 + ∂2∂ 2 + ∂2∂ 2 (3)

The energy per unit length associated with the element is given by the following equation:

� =1/2 �[ �]�[� � ][ �] … ( (4)

Where, T denotes the transpose of the matrix

[Ve] = [ �� ] And [� � ] = [� � � � � �� ] (5)

5. DIMENSIONS OF INSULATOR AND SIMULATION

Insulators used for high-voltage power transmission are made from glass, porcelain, or

composite polymer materials. Porcelain insulators are made from clay, quartz or alumina

and feldspar, and are covered with a smooth glaze to shed water. Insulators made from

porcelain rich in alumina are used where high mechanical strength is a criterion. Porcelain

has a dielectric strength of about 4–10 kV/mm.

Figure 5.1: Dimensions of Ceramic Disc Insulator

The design of cap and pin type ceramic insulator essentially consists of a malleable/ductile

iron cap, malleable/forged iron pin and a ceramic/porcelain shell. The cap and pin of the

insulator is fixed to the ceramic shell with the help of a Portland cement. A bituminous

coating is applied to the pin to prevent corrosion. The dimension of insulator used are

given for each model in the CATIA models as shown in Figure 5.2

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Figure 5.2: Dimension of insulator in CATIA

Table 5.1: Details of materials used for Insulator

Altair Hyper View is a complete post-processing and visualization environment for finite-

element analysis (FEA), multi-body system simulation, video and engineering data. Hyper

View can visualize data interactively, as well as capture, standardize and automate post-

processing activities.

Hyper View also saves 3D animation results in Altair's compact H3D format. This enables

users to visualize and share CAE results within a 3D web environment and Microsoft

PowerPoint. The model of insulator after importing in the HYPERMESH is as shown in

Sl. No CATIA models

parts No. Material model no

Voltage on

nodes(volts)

1 Part1 (Cap of

insulator)

Material model 1

(ground end) 0v

2 Part2 (Binding

cement)

Material model 2

(Cement part) -

3 Part3(Ceramic

surface)

Material model 3(Disc

part) -

4 Part4(Pin of

insulator)

Material model 4(Pin

part) 11kv

5 Part5 (air part) Material model 5(air

part) -

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Fig.5. Details of material type, relative permittivity of different parts of the modeled

insulator, the model of insulator after importing in the HYPERMESH.

Figure 5.3: Model of insulator after importing in the HYPERMESH

The contour plots of potential and field distributions of standard ceramic insulators are

shown in Figure 5.4. Potential distribution of standard normal type ceramic insulator

Figure 5.4: Potential distribution in ANSYS

Electric field distribution of standard normal type ceramic insulators is shown in Figure

5.5

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Figure 5.5: Electric field distribution in ANSYS

The results from the simulations were given in figures. The potential distribution plots for

the clean and dry insulators were also shown in figures. These figures show that the

voltage is fairly evenly distributed over the insulator surface from live end to dead end.

6. CONCLUSIONS

Simulation have been carried out on this standard single disc type of insulator and other

two simulations were also done on it by varying its air distances (i.e. width of rib) of first

and third ribs. Based on these discussions the following conclusions were drawn.

The potential distribution for all the three cases remains unaltered. The underside

corrugations do not affect the potential distribution.

The maximum field occurs at the pin region in comparison to the average field

along the surface of the insulator in all the three cases.

14 %- 17 % of the transmission line voltage is developed across the nearest

insulator to the line-end. The voltage sharing on the other insulators considerable

degreases toward the earth end. The potential is distributed in relations to the self

and stray capacitances.

With the usage of grading device, 12 % - 14 % of the line voltage is shared by the

line-end insulators. Increase in the line stray capacitances results in slightly

potential rises on the insulators near the ground end.

Potential distribution under porcelain and toughened glass insulators has nearly 2

% differences because of the dielectric constant of the mediums.

7. SCOPE FOR FUTURE WORK In the present work, a finite element field simulation package was used to study the

electric field surrounding an energized ceramic insulator under clean and dry conditions.

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But power line insulators were used to support the high voltage current carrying

conductors. Due to the geometry of the line and insulator, the voltage distribution along

the length of the insulator is non-uniform. When the ceramic insulators are installed on 3-

phase power line, the conductors, tower configuration for different voltages and other two

phases of the 3-phase system can influence the electric field and potential distribution in

the vicinity of the insulators. Therefore, a lot of scope for further study on the electric field

and potential distribution in the vicinity of the insulators considering all the above effects

from the practical standpoint.

8. REFERENCES

[1] S. Chakravorti, and H. Steinbigler, “Boundary-Element Studies on Insulator Shape and

Electric Field around HV Insulators with or without Pollution,” IEEE Transactions on

Dielectrics and Electrical Insulation, Vol. 7, No. 2, April 2000, pp. 169-176.

[2] Biswanath malik, ”Electric field calculations by numerical Techniques”, department of

electrical engineering national institute of technology rourkela-769008 2009

[3] World Academy of Science, “Numeric method for electric field computation” Engineering

and Technology 53 2009

[4] T. Misaki, H. Tsuboi, K. Itaka, and T. Hara, “Optimization of Three-dimensional

Electrode Contour Based on Surface Charge Method and Its Application to Insulation

Design,” IEEE Transactions on Power Apparatus and Systems, Vol. 102,No. 6, June

1983, pp. 1687-1692.

[5] S. Kaana-Nkusi, P. H. Alexander, and R. Hackam, “Potential and Electric Field

Distributions at a High Voltage Insulator Shed,” IEEE Transactions on Dielectrics and

Electrical Insulation, Vol. 23, No. 2, April 1988, pp. 307-318.

[6] F. Gutfleisch, H. Singer, K. Forger, and J. A. Gomollon, “Calculation of High- Voltage

Fields by Means of the Boundary Element Method,” IEEE Transactions on Power

Delivery, Vol. 9, No. 2, April 1994, pp. 743-749.

[7] S. Ilhan, A. Ozdemir. “Study on Potential and Electrical Field Distribution along 380 kV

V-Insulator String Using Boundary Element Method”

[8] Qing Yang, Rui Wang, Wenxia Sima, Tao Yuan and Lei Liao “Improvement of the

Electric Field Distribution around the Ends of Composite Insulator with Series

Connection of Glass Insulator” Chongqing University

[9] E. H. Allen and P. L. Levin, 1993, “Two dimensional and Axi-symmetric Boundary value

problems in Electrostatics”, Computational Fields Laboratory, Dept. of Electrical and

Computer Engineering, Worcester Polytechnic Institute, Worcester, MA-USA -1993

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International Journal of Informative & Futuristic Research ... · x 14 %- 17 % of the transmission line voltage is developed across the nearest insulator to the line-end. The voltage