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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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Generation of HARMONICS in Current Waveform
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Generation of HARMONICS in Current Waveform
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Generation of HARMONICS in Current Waveform
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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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