RETHWAN FAIZ Course instructor:

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Group no: 7Group Members Md.Kamruzzaman kousar 12-20506-

1 Ahmed,S.M. Ishfaq 13-

23626-1 Talukder,Saiful Islam 13-

24165-2 Firoz,A.M.M 13-

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“ Power Factor Correction “

OUTLINE

DEFINITION CAUSES OF LOW POWER FACTOR

Importance of power factor Correction POWER FACTOR CORRECTION

ADVANTAGES OF POWER FACTOR CORRECTION

DISADVANTAGES OF LOW POWER FACTOR

CONCLUSION

REFERENCES

Power factor ↑ =Save money

DEFINITION

Power factor (P.F) is the ratio between actual power to the apparent power.

P.F= Actual power/Apparent power (Kw /Kva)

Power equations

power factor

3 type of P.F→

Unity P.F (pure resistive load)Capacitive load (leading P.F)Inductive Load (Lagging P.F)

Load curves: Consumers get :

Power factor type

Unity power factor

Lagging power factor (for Inductive load)

Power factor type

Leading power factor(for capacitive load)

Phasor diagram

Why is Power Factor Important?

Consider the following example: A generator is rated at 600 V and supplies one of two possible loads.Load 1: P = 120 kW, FP = 1Load 2: P = 120 kW, FP = 0.6

How much current (I) is the generator required to supply in each case?

Load600 V

+

-

I

120 kW

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DISADVANTAGES OF LOW POWER FACTOR Increases heating losses in the transformers

and distribution equipments. Reduce plant life. Unstabilise voltage levels. Increase power losses. Upgrade costly equipments. Decrease energy efficiency. Increase electricity costs by paying power

factor surcharges.

Why is Power Factor Important?

For the load with Fp = 0.6, the generator had to supply 133 more amperes in order to do the same work (P)!

Larger current means larger equipment (wires, transformers, generators) which cost more.

Larger current also means larger transmission losses (think I2R).

Why is Power Factor Important?

Because of the wide variation in possible current requirements due to power factor, most large electrical equipment is rated using apparent power (S) in volt-amperes (VA) instead of real power (P) in watts (W).

Is it possible to change the power factor of the load?

POWER-FACTOR CORRECTION

FIG. 19.28 Demonstrating the impact of power-factor correction on the power triangle of a network.

Single-phase Supply with Power Factor Correction

P.F correction circuit Phasor diagram

P.F Correction

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DETERMINING CAPACITOR VALUE

Example Power Factor1=74% Actual Power=594 kw Interested to boost up=97% ,Power

Factor2=97% Power Factor=KW/KVA Cos = kW / kVA = Cos-1 (PF1) = Cos-1 (74%) =42.27 o

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The reactive power was about: Tan = kVAr / kW kVAr = kW x tan kVAr = 594 kW x tan (42.27) = 540 kVAr If the power factor were increased to 97%, the

reactive power would be about: Cos = kW / kVA = Cos-1 (PF2) = Cos-1 (97%) = 14.07 o kVAr = kW x tan kVAr = 594 kW x tan (14.07) = 149 kVAr

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Thus, the amount of capacitance required to boost power factor from 74% to 97% :

540 kVAr – 149 kVAr = 391 kVAr So I recommended 400kvar

Power Factor Correction Almost all loads are inductive. In order to cancel the reactive

component of power, we must add reactance of the opposite type. This is called power factor correction.

Capacitor bank in shipboard power panel for FP correction

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POWER CAPACITORSPower Factor correction on site with Pole Cap

Power factor correction capacitors for A, B, and C phases at the Crofton , MD substationRating: 230 kV, 360 MVAR

size comparison Capacitor banks

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ADVANTAGES OF POWER FACTOR CORRECTION

Eliminate Power Factor Penalties Increase System Capacity Reduce Line Losses in distribution systems Conserve Energy Improve voltage stability Increase equipment life Save on utility cost Enhance equipment operation by improving voltage Improve energy efficiency Less total plant KVA for the same KW working power Improved voltage regulation due to reduced line voltage drop Reduction in size of transformers, cables and switchgear in

new installations

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DISADVANTAGES OF LOW POWER FACTOR Increases heating losses in the transformers

and distribution equipments. Reduce plant life. Unstabilise voltage levels. Increase power losses. Upgrade costly equipments. Decrease energy efficiency. Increase electricity costs by paying power

factor surcharges.

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CONCLUSION

By observing all aspects of the power factor it is clear that power factor is the most significant part for the utility Company as well as for the consumer. Utility company rid of from the power losses while the consumer free from low power factor penalty charges.

By installing suitably sized power capacitors into the circuit the Power Factor is improved and the value becomes nearer to 1 thus minimising line losses and improving the efficiency of a plant.

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REFERENCES

Electrical Power System Design and Analysis by M.E.EI-Hawary. Power System Operations by Robert H Miller. IEEE papers www.ABB.com BC Hydro (www.bchydro.ca)

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