Power Factor Correction (1)

8/3/2019 Power Factor Correction (1)

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Power Electronics 1 (ELAE210E)

Emerson Power Elec Scholars Batch 16

Engr. Ernesto Vergara

Instructor


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1 Power factor in linear circuits

Definition and calculation

Importance of power factor in distribution systems

2 Power Factor Correction for Linear Loads3 Power Factor Correction for Non-linear Loads

Non-sinusoidal components

2.2 Distortion power factor

2.3 Switched-mode power supplies

2.4 Power factor correction in non-linear loads

2.4.1 Passive PFC

2.4.2 Active PFC


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The product of the RMS voltage and RMS current.

Measured in VA.

S = Vrms*IrmsS = P + jQ

S = P/cos() S = Q/sin()


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The actual power dissipated by the load. Measured

in Watts.

P = S*cos()P = Q/tan()


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It is the measure of the exchange of power

between the source and the load. Measured in

VAR.

Q = S*sin()

Q = Ptan()


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The power factor of an AC electric power

system is defined as the ratio of the real

power consumed by the load to the total

apparent power drawn by the circuit, and is adimensionless number between 0 and 1

pf = cos()


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The process of increasing the power factor without

altering the voltage or current to the original load.

Q = P[tan(1) tan(2)]


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Reduces effective capacity of power supply

-more reactive power = less real power

Penalties for poor pf

-reactive power charges

-increased kWhr charges

Systems Losses

-transformer-increased CO2 emissions

-equipment life cycle


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Removal of reactive power charges

Reduce cost of electricity

Improve supply efficiency

Reduced CO2 emissions


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Apparent Power

RealPowerBoat

Horse

Reactive Power = 0

0


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BoatRealPower

Horse

Reactive Power

Apparent Power

1


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Apparent Power

RealPowerBoat

Horse

2Reactive Power


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When connected to a 120Vrms 60Hz power-line, a

load absorbs 4kW at a lagging power factor of 0.8.Find the value of capacitance necessary to raise the

pf to 0.95.


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Traditional methods of Power Factor Correction

typically focus on Displacement Power Factor

and therefore do not achieve the total energy

savings available in facilities having both linearand nonlinear loads. Only through Total Power

Factor Correction can the savings and power

quality be maximized.


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AC electrical loads where the voltage and

current waveforms are sinusoidal. The

current at any time is proportional to

voltage.

Examples of Linear Loads are:

Power Factor Improvement Capacitors

Incandescent Lamp

Heaters, etc


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AC loads where the current is not proportionalto the voltage. The nature of non-linear loadsis to generate harmonics in the currentwaveform. This distortion of the current

waveform leads to distortion of the voltagewaveform. Under these conditions, the voltagewaveform is no longer proportional to thecurrent.

Non Linear Loads are : COMPUTER, LASER PRINTERS, SMPS, REACTIFIER,

PLC,

ELECTRONIC BALLAST, REFRIGERATOR, TV ETC.


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Generation of HARMONICS in Current Waveform


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Recall: FOURIER SERIES


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Total power Factor

Displacement Power Factor

Distortion Power Factor


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Power Factor

Real Power

Apparent Power

Reactive PowerHarmonics


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Power Factor Correction (1)

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