AN APPLICATION OF MS-EXCEL FOR COMPUTATION OF...

43 Prof. Manan M. Desai, Ghadiya Kishan S., Gohel Tushar M., Baraiya Yogesh

International Journal of Electronics, Electrical and Computational System

IJEECS

ISSN 2348-117X

Volume 6, Issue 4

April 2017

AN APPLICATION OF MS-EXCEL FOR COMPUTATION

OF VARIOUS TRANSFORMER PARAMETERS

Prof. Manan M. Desai4

Assistant Professor DegreeElectrical Engineering

Dr. Subhash Technical Campus, Junagadh

Ghadiya Kishan S.1

Gohel Tushar M.2 Baraiya Yogesh

3

Student of Electrical

Department


Department


Department

Dr. Subhash Technical Campus Dr. Subhash Technical Campus Dr. Subhash Technical Campus

Junagadh Junagadh Junagadh

ABSTRACT Transformer is a very important part of any substations, which affects overall costing of transmission and distribution

budgets. So, it is necessary to design economical, viable, low weight, small size efficient transformer.The design of

transformer depend to large extent on the specific requirement of the customer. The main objective of our project is to

develop a program for transformer design using Excel sheet. This Programming has ability to execute many difficult and

reiterative calculations and step-wise procedure leading to a design that satisfies all input specification.With the

Calculation technologies in the power industry, new references addressing new technologies are coming to the market.

Based on this fact, there is an urgent need to keep track of international experiences and activities taking place in the

field of modern transformer design. The complexity of transformer design demands reliable and rigorous solution

methods. A survey of current research reveals the continued interest in application of advanced techniques for

transformer design optimization. This paper conducts a literature survey and reveals general backgrounds of research

and developments in the field of transformer design and optimization for the past 30 years, based on more than 200

published articles, 25 transformer books, and 50 standards.[1]

Keywords :-Microsoft excel, visual basic, power system analysis, equivalent circuits, experimental methods,

numerical techniques, standards, survey, transformer books, transformer design optimization.

1. Introduction

Transformer design is a complex task in which engineers have to ensure that compatibility with the imposed

specifications is met, while keeping manufacturing costs low. Moreover, the design methodology may vary

significantly according to the transformer type (distribution or power transformer) and its operating frequency

(ranging between 50/60 Hz and a few MHz), while many alterations according to the core constructional

characteristics, the cooling method, or the type of the magnetic material may be encountered. This paper

provides an overview of research, development and application of various computational methods for

transformer design, based on an extensive number of published papers. The review is divided into two major

sections: research efforts focusing on the prediction and/or optimization of specific transformer characteristics

(mainly losses and short-circuit impedance) and techniques adopted for global transformer design

optimization, taking into account all the relevant performance parameters.[2]

2. Methodology Design

With the rapid development of the digital computer, designers are no longerassist to their performance of the

routine calculations. Computer is widely use in optimized of transformer designwithintheir matter of the

seconds. We have make an excel sheet that includes transformer parameter calculation easily.



IJEECS

ISSN 2348-117X

Volume 6, Issue 4

April 2017

These are the input parameters of transformer :-

• KVA rating of Transformer

• Primary voltage

• Secondary voltage

• No load losses

• No load current

• Full load losses

• Impedance voltage

• LV resistance in mili ohms

• HV resistance in ohms

• Amb temperature

• Total Connected Load on Transformer

Above transformer data include in excel sheet and we got the calculation of transformer parameters.

3. CASE STUDY

This section presents the mathematical formulation of the objective function, design variables, and design

constraints for distribution transformer design optimization. This technique is integrated in excel environment,

using suitable graphical user interface. The transformer inputs involves design parameters, such as rated

power, voltages, etc., comprises of the upper/lower limits and the initial value of the design. For optimizing

the transformer design is based on the minimization of the overall transformer cost function.

3.1Formula

HV Full load current = VA / (1.732xVolt)

LV Full load current = VA / (1.732xVolt)

HV Side I2R losses = I²R x1.5

LV Side I²R losses = I²R x0.5x3

Total I² R losses @ Amb temp = Hv losses + Lv losses

Total Stray losses @ Amb temp = Measured losses -I² R losses

I² R losses @75° c temp = ((225+75) x losses) / (225+ Amb temp)

Stray losses @ 75° c temp = ((225+Amb temp)(Stray losses at amb)) / 300

Total Full load losses at @75° c = I²R losses at 75°c+Stray losses at 75°c

Total Impedance at ambient temp = (Imp voltage x 1.732) / Full load current

Total Resistance at ambient temp = I²R losses / I²

Total Reactance (X) = SQRT(Impedance ²- Resitance ²)

Resistance at@ 75° c = (300 x resistance at ambient ) /(225+Amb temp)

Impedance at 75° c = SQRT(R² at 75 + X²)

Percentage Impedance = (Z at 75° c x I x 100)/V1

Percentage Resistance = ( R 75° c x I x 100)/V1

Percentage Reactance = (X x I x 100) / V1

Regulation at Unity P.F = (%R cosø+%Xsinø)

Regulation at 0.8 p.f. =(%R cosø+%Xsinø)+1/200(%R sinø-%Xcosø)2"

Efficiency at Unity P.F

o At 125 % of Transformer Loading =

(Kva x 1.25 x 100)/((kva x 1.25)+(I²R losses x 1.25²)+(No Load Losses))

Efficiency at 0.8 P.F

o At 125 % of Transformer Loading =

(Kva x 1.25xp.f x 100)/((kvaxp.fx 1.25)+(I²R losses x 1.25²)+(No Load Losses))

3.2 Parameter Caculations

I2R Losses :-

1. LV Full load current = (KVA rating of Transformer)/( Secondary voltage*1.732)



IJEECS

ISSN 2348-117X

Volume 6, Issue 4

April 2017

= (16000)/(11000*1.732) = 0.84 Amps

2. LV Full load current = (KVA rating of Transformer)/( Secondary voltage*1.732)

= (16000)/(433*1.732) = 21.33 Amps

3. HV Side I²R losses =〖(HV Full Load Current)〗^2* HV resistance*1.5

= (0.84*0.84)*215*1.5 = 227.80 Watts

4. LV Side I²R losses =〖(LV Full Load Current)〗^2* LV resistance*1.5

= (21.33*21.33)*219.16mΩ*1.5 = 149.56 Ohms

5. Total I² R losses @ Amb temp = HV Side I²R losses + LV Side I²R losses

= (227.80)+(149.56) Ω = 377.43 Ohms

6. Total Stray losses @ Amb temp= (LV Side resistance in mili Ω) - Total I² R losses @ Amb temp

= (219.16mili ohm’s) –(377.43 watts) = 16.57watts

7. Total I² R losses @75`C Amb temp = ((225+75) total I²R losses) / (225+ Amb temp)

= ((225+75) x337.43) / (225+ 30) = 441.52Watts

8. Stray losses @ 75° c temp = ((Total Stray losses @ Amb temp)*(235+ Amb temperature))/(310)

= ((16.57watts)*(235+ 30))/(310) = 14.16Watts

9. Total Full load losses at @75° c =

=( Total I² R losses @75`C Amb temp)+( TotalStray losses @ 75° c temp)

= (441.52Watts)+(14.16Watts) = 455.9 Watts

10. Total Impedance at ambient temp = ( Impedance voltage*1.732)/( HV Full load current)

= 480*1,732)/(0.84) = 989.54 Ohms

11. Total Resistance at amb temp = ( Total I²R losses @ Amb temp)/((HV Full Load Current)2)

= ( 377.43)/(0.84)2 = 535.15 Ohms

12. Total Reactance (X) = SQRT(Impedance ²- Resistance ²)

= SQRT((989.94) ²- (535.15) ²) = 832.82Ω

13. Resistance at@ 75° c = (310 *total resistance at ambient ) /(225+Amb temp)

= (310 *535.15) /(225+30) = 625.03Ω

14. Impedance at@ 75° c = SQRT(R² at 75 + X²)

= SQRT((625)2 + (832.82)2) = 1041.88Ω

15. Percentage Impedance = (Impedance*0.5774*HV Load Current*100)/(Primary Voltage)

= (1041.88*0.5774*0.84*100)/(11000) =4.59%

16. Percentage Resistance = (Resistance at 75 c*0.5774*HV Load Current*100)/(Primary Voltage)

= (535.15*0.5774*0.84*100)/(11000) =2.76%

17. Percentage Reactance = (Total Reactance *0.5774* HV Load Current *100)/(Primary Voltage)

= (832.82Ω *0.5774* 0.84*100)/(11000) =3.67%



IJEECS

ISSN 2348-117X

Volume 6, Issue 4

April 2017

Regulation Calculation:-

1. Regulation at Unity P.F = (%R cosø+%Xsinø)

= ((2.75*0.8)+ (3.67*0.6)) = 2.76

2. Regulation at 0.8 P.F = (%R cosø+%Xsinø)+1/200(%R sinø-%Xcosø)2

=( 2.75 ∗ 0.8 + (3.67 ∗ 0.6)) + 0.005((2.75 ∗ 0.6) + (3.67 ∗ 0.8))2 = 4.43%

Efficiency Calculation:-

1. Efficiency at Unity P.F = (KVA*1.25*100)/((KVA* 1.25)+(I²R losses*1.25²)+(No Load Losses))

= (16000*1.25*100)/((16000*1.25)+(377.45*1.25²)+(72)*100 = 96.80%

2. Efficiency at 0.8 P.F =

= (KVA x 1.25xp.f x 100)/((KVA xp.fx 1.25)+(I²R losses x 1.25²)+(No Load Losses

= (16000*1.25*.8*100)/((16000*1.25*0.8+(377.45*0.8*1.25²)+(72)*100 = 99.52%

4. RESULT

Now a day to calculate transformer parameters method is very lengthy, hard and it take a so much time of

operators. So, we make this project to calculate transformer parameter and it is very easy and give output

within there matter of seconds.

I²R losses Calculation:-

Theoretical Calculation Practical Calculation

HV Full load current :- 0.83 A HV Full load current :- 0.84 A

LV Full load current :- 21 A LV Full load current :- 21.33 A

HV Side I²R losses :- 225 W HV Side I²R losses :- 227.80 W

LV Side I²R losses:- 150 W LV Side I²R losses:- 149.63 W

Total I² R losses @ ambient temp:- 376 W Total I² R losses @ ambient temp:- 377.43 W

Total Stray losses @ ambient temp:- 15 W Total Stray losses @ ambient temp:- 16.57 W

I² R losses @75° c temp:- 441 I² R losses @75° c temp:- 441.52 W

Stray losses @ 75° c temp:- 15 W Stray losses @ 75° c temp:- 14.16 W

Total Full load losses at @75° c :- 455 W Total Full load losses at @75° c :- 455.69 W

Total Impedance at ambient temp:- 989 Ω Total Impedance at ambient temp:- 989.94 Ω

Total Resistance at ambient temp:- 535 Ω Total Resistance at ambient temp:- 535.15 Ω

Total Reactance (X):- 831 Ω Total Reactance (X):- 832.82 Ω

Resistance at@ 75° c:- 626.35 Ω Resistance at@ 75° c:- 626.03 Ω

Impedance at 75° c :- 1041.20 Ω Impedance at 75° c :- 1041.88 Ω

Percentage Impedance:- 4.60 % Percentage Impedance:- 4.59 %

Percentage Resistance :- 2.65 % Percentage Resistance :- 2.67 %

Percentage Reactance :- 6.66 % Percentage Reactance :- 3.67 %



IJEECS

ISSN 2348-117X

Volume 6, Issue 4

April 2017

Regulation Calculation :-

Theoretical Calculation Practical Calculation

Regulation at P.F of unity :- 2.75 % Regulation at P.F of unity :- 2.76 %

Regulation at P.F of 0.8 :- 4.43 % Regulation at P.F of 0.8 :- 4.43 %

Efficiency Calculation :-

Efficiency at P.F of Unity:- Efficiency at P.F of Unity:-

At Transformer Loading 125% :- 96.75 % At Transformer Loading 125% :- 96.80 %

Efficiency at P.F of 0.8 Efficiency at P.F of 0.8

At Transformer Loading 125% :- 99.50 % At Transformer Loading 125% :- 99.52 %

5. CONCLUSION

In this projectwe got the information and practical knowledge about Transformer. We got the knowledge

about different type of transformer testing, I² R loss, efficiency, regulation, outer and inner part of transformer

like core, winding, relay etc. We have make an excel sheet that includes transformer parameter calculation

easily. Because all calculations is done by there programming, by human errors is eliminated which turn

eliminate cost associated by these.These project are very useful for industrial and power supplier. by use this

software they not need any external document require.

6. REFERENCES [1] Eleftherios I. Amoiralis, Marina A. Tsili,and Antonios G. Kladas,IEEETransactions on Power Delivery. November

2009 DOI:10.1109/TPWRD.2009.2028763. Source: IEEE Xplore

[2] Eleftherios I. Amoiralis, Marina A. Tsilia, Pavlos S. Georgilakis,Journalof optoelectronics and advanced materials

Vol. 10, No. 5, May 2008, p. 1149 – 1158

[3] K. Zakrzewski, B. Tomczuk, and D. Koteras, “Simulation of forces and 3-D field arising during power

autotransformer fault due to electric arc in HV winding,” IEEE Trans. Magn., vol. 38, no. 2, pp. 1153–1156, Mar.

2002.

[4] American Journal of Engineering Research (AJER) e-ISSN : 2320-0847 p-ISSN : 2320-0936 Volume-4, Issue-2, pp-

133-145

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