Free Particle Movements Simulation in a 1- Gas Insulated ...

Free Particle Movements Simulation in a1-φ Gas Insulated Bus duct Using

Dielectric Coating

Dr. K B V S R Subrahmanyam1,Dr.M.Ramesh2,3Dr.Ram deshmukh

1Assoc.Prof,2,3professor1,2,3EEE Dept.

1,3S R Engg.College,Warangal2Vaageswari college of Engg,

Karimnagar .1libra [email protected]

[email protected]@gmail.com

October 11, 2018

Abstract

The image charge effect on the Particle motion inside aGas Insulated Bus duct (GIB) of single phase using epoxyresin coating of dielectric on the inner surface of GIB outerenclosure is presented in this paper. Taking into accountmany forces like drag, gravitational and the electrostaticacting on the free conducting particle, a mathematical modelwas derived. The differential equation of second order forthe motion of the particle is solved and restitution coefficientwas considered at each impact of particle with the GIB en-closure . At the particle locations, computation of electricfields instantaneously was made using the Charge Simula-tion Method (CSM). The motion of the metallic particle inthe absence of image charge effect are compared with in the

1

International Journal of Pure and Applied MathematicsVolume 120 No. 6 2018, 405-416ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

405

presence of effect of image charge. Based on the results,it can be observed that the movement with effect of imagecharge is more than the movement without effect of imagecharge . Using 100kV, 145kV, 175kV and 220kV class, thesimulation is worked for several bus configurations with alu-minum and copper particles inside GIB. Analysis of all theresults were done and presented in this paper.

Key Words:: Metallic Particle, Gas Insulated Bus duct,Dielectric coating, Charge Simulation Method.

1 Introduction

Basically, in a GIB, a compressed Sulphur Hexafluoride (SF6) gaschambers are enclosed with live parts. Although, SF6 gas showsgreater dielectric strength, the voltage withstand of SF6 within theGIB is decreased to the greater extent due to existence of metal-lic particles. So, the performance of electrical insulation of GIBis greatly affected by these particles and in the survey of CIGRE,it was found that failures about 20% in GIB are be the becauseof various contaminations of metallic particle presence in the formof particles of loose in nature[1]-[3]. Compressed GIS reliabilitywill be improved, if these particles are eliminated [4],[5]. Differentcontrol of particle conducting methods and deactivation have beensuggested[6,7] and coating of the dielectric of the outer enclosureon the inner surface is among them. This work mainly describesthe metallic movement of the particle in dielectric coated GIB (1-).with electric field in the presence and absence of image charge ef-fect. In GIB, Charge Simulation Method (CSM) is the method usedfor computing the electric fields. In this work, by using dielectriccoating of the inner surface of the outer enclosure with a light shadeof epoxy resin micron thickness, the performance of the dielectricwill be improved, thereby reducing the particle movement and thelift-off field increases.

2 GIB MODELING TECHNIQUE

A single phase GIB consisting of conductors with coated dielec-tric outer enclosure with filled SF6 gas as shown in fig.1 is taken

2

International Journal of Pure and Applied Mathematics Special Issue

406

into account. It is assumed that a particle (filamentary type) isresting on the coated dielectric of the outer enclosure on the innersurface of GIB. Different mechanisms of charging the particles are:1. Through dielectric coating, conduction 2. Micro discharges be-tween dielectric coating and the particle [4]. The particle beginsto lift and move, once the particle possess the charge in the elec-tric field direction having overcome all the forces due to its owndrag and weight [5,6,7]. The simulation takes into account differ-ent parameters like its weight, viscosity of the gas, the macroscopicfield at the location of the particle ,Reynolds number, restitutioncoefficient and drag coefficient [6] .

Fig.1 Single phase common enclosure GIBThe motion equation can be stated as,

Where m = particle mass, y = vertical direction displacement ,Fe = force due to Electrostatic, g = gravitational constant, Fd =Force due to drag. The equation of motion of the particle utilizingall forces can be stated as[3-5]:

3


407

Fig.2 Particle charging circuit model through coating ofdielectricB

In Fig.2, the particle charging circuit model through the dielectriccoating is as shown. Cg is the capacitance between the particle andthe phase conductor and Cc is the capacitance between the particlecapacitance and the enclosure.The metallic particle lift-off field Elocan be obtained as,

Where K is a constant.

3 PARTICLE MOTION SIMULATION

The Particle motion simulation knowledge in a GIB needs the chargemagnitude possessed by the particle at the location of metallic par-ticle and electrostatic field present. In GIB, Charge SimulationMethod is used for calculating electric field based on the work ofNazar H. Malik et al[8] and H.Singer [9].

4


408

3.1 CHARGE SIMULATION METHOD

Figure 3 describes the concept basic behind the ambient electricfield computation at any time using charge simulation method inGIB of single phase.

Fig 3. Charge Simulation Method ConceptAt point p(x,y), the Electrostatic field in the absence of the image

charge is computed as

At point p(x,y), the Electrostatic field in the presence of imagecharge is computed as

5


409

3.2 MONTE-CARLO TECHNIQUE

Using 4th Order RK method, the metallic particle equation of mo-tion is solved and it specifies the the radial direction movement.Calculation of movement in axial direction of the metallic parti-cle was done using method of Monte-carlo simulation based onJ.Amarnath et al[1],[2],[5] works. Using Advanced C LanguageProgram, computer simulations was done in GIB with diameterof inner conductor 27.5mm and diameter enclosure of 76mm for100kV, 145kV, 175kV and 220kV applied voltages. Particles likeAluminum and copper are assumed on the enclosure surface.

4 RESULTS AND DISCUSSIONS

Using RK 4th order method and Monte-Carlo Technique, metallicparticle motion equation was solved for particles like aluminium andcopper and the results are obtained. Determination of the Electricfields was done by the absence of image charge mentioned in (4) and(5) equations and in the presence of image charge with equations(6) and (7). Table I and Table II show the aluminium and cop-per particles movement patterns for voltages of power frequency.512 fictitious charges in conductor and with 1.5 assignment fac-tor are considered for computing electric field in single phase GIBfor the presence and absence of image charges with charge simu-lation method. In all the cases discussed, radius of particles likealuminium and copper are taken into account as 0.01 mm, lengthas 12 mm, restitution coefficient as 0.9 and gas pressure as 0.4Mpa.

Table I Aluminum and Copper particles Peak Radial Movementsin the presence and absence of image charge effect

6


410

Table I describes the peak movements in radial direction for alu-minium and copper particles for several voltage levels in the pres-ence and absence of effects of image charge.For Aluminium parti-cles having no effect of image charge, the movement is 4.7939mmand in the presence of effect of image charge, the peak movementis 8.3856mm for 100kV and it is noted that these movements in-crease with applied voltage increase. The peak radial movementis 15.0353 mm and 20.9076 mm as shown above respectively at220KV. Similarly, the radial movement is 7.5mm for in the pres-ence and absence of image charge effect for Copper particles and12.3247mm for the presence of image charges at 220KV. In a simi-lar manner, for 220kV, the peak axial movement in the absence ofeffect of image charge is 66.9962mm for Aluminium particles andin the presence of effect of image charge is 65.6032mm. It can beobserved that the Aluminium particles axial movements are rapidlyincreasing with voltage level up to 145kV and decreasing with volt-age increasing upto 175kV and again axial movement is increasingwith voltage upto 220kV. For 220kV, Peak axial movements arereaching 73.8958mm and 98.5393mm for electric fields calculatedin the absence and presence of effects of image charge respectively.At 100KV, the peak movement in axial direction is 37.5593mm and59.2602mm for Copper particles. Copper particles peak movementsin axial direction are raising with voltage raise up to 175kV and af-ter these peak axial movements are slowing down for Aluminiumparticles with increase of voltage. All the above results are tabu-lated in Table II shown below.

Table II Al and Cu particles Maximum Axial Movements in thepresence and absence of image charge effect using Monte-Carlo

simulation (10).

7


411

Figs. 3 to 10 show the movement patterns in radial direction of alu-minum and copper particles using CSM in the absence and presenceof effect of image charge for voltage levels of 100kV and 220kV.

8


412

9


413

5 Conclusion

To simulate the particle movement, a mathematical model was de-veloped in the presence of electric field in single phase GIB. It canbe noted from the above results that particles made of Aluminiumhave greater impact on voltage compared to copper particles dueto its lighter weight. Hence, the aluminum particle acquires higherratio of charge-to-mass. A method named Monte-Carlo simulationwas used for finding axial and radial particle movements in GIB.From the above results, it can be inferred that peak particle move-ment in electric field with image charge effect is more than withoutimage charge. The performance of the insulation improves, if theinner surface of the outer enclosure was given dielectric coating of alight shade with micron thickness epoxy resin, This is done by thereduction of the charge on the particle and hence the peak move-ment reduces . All the above discussions were done for differentvoltage levels with frequency.

6 ACKNOWLEDGMENT

The authors are greatful to the managements of S R EngineeringCollege, Warangal and Vaageswari college of Engineering, Karim-nagar for providing resources in publishing this work.

References

[1] J. Amarnath, B.P. Singh, C. Radhakrishna and S. Kamak-shiah, Determination of Particle trajectory in a Gas Insu-lated Busduct predicted by Monte-Carlo technique, IEEE Con-ference on Electrical Insulation and Dielectric Phenomena(CEIDP), Texas, Austin, USA, 1991 Vol.1, pp. 399- 402,1991.

[2] J. Amarnath, S. Kamakshaiah, C. Radhakrishna, B.P. Singhand K.D.Srivastava, Particle Trajectory in a Common Enclo-sure Three phase SF6 Busduct, 12th Intern. Sympos. HighVoltage Eng., IISc, Bangalore, India, Vol. 2, pp. 441-444, 2001.

10


414

[3] H.Anis and K.D.Srivastava Free conducting particles in com-pressed gas insulation, IEEE Tranctions on electrical insula-tion, Vol. EI-16, pp.327- 338, August 1995.

[4] M. M. Morcos, S. Zhang, K. D. Srivastava and S.M.Gubanski,Dynamics of Metallic Particle Contaminants inGIS with Dielectric-Coated Electrodes, IEEE Trans. on PowerDelivery,Vol.15, No. 2, Apr 2000, pp. 455-460.

[5] J. Amaranath, S. Kamakshiah and K.D. Srivastava. 2001. In-fluence of Power Frequency and Switching Impulse Voltageon particle Movement in Gas-predicted by Monte-Carlo Tech-nique. IEEE, Intern. High Voltage Workshop, California, USA.

[6] G.V.Nagesh Kumar, J.Amarnath and B.P.Singh, Behavior ofMetallic Particles in a Single Phase Gas Insulated Systemwith Dielectric Coated Electrodes, International Conferenceon Condition Monitoring and Diagnosis, Beijing, China, April21-24, 2008.

[7] K.B.Madhu Sahu and J.Amarnath, Effect of Various Parame-ters on the Movement of Metallic Particles in a Single PhaseGas Insulated Busduct with Image Charges and DielectricCoated Electrodes, ARPN Journal of Engineering and AppliedSciences, Vol.5, No.6, June 2010, pp.52-60.

[8] Nazar H.Malik, A Review of the Charge Simulation Methodand its Applications, IEEE Trans, Electr. Insul., Vol, 24, pp.3-20, 1989.

[9] H.Singer, H.Steinbigler and P.Weiss, A Charge SimulationMethod for the Calculation of High Voltage Fields, IEEEPower Engineering Society, 1974.

11


415

Free Particle Movements Simulation in a 1- Gas Insulated ...

Documents

Transcript of Free Particle Movements Simulation in a 1- Gas Insulated ...