Fundamentals of Harmonics

1
Fundamentals of Harmonics
2
Overviews

• Definitions and Nonlinear Loads
• Harmonics Power Quantities
• Harmonic Sequences
• Triplen Harmonics
• Harmonics Indices
• Harmonic Sources
• Classical Sources and Power Electronics
• Locating Harmonic Sources
• Impacts of Harmonics
• Interharmonics

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1.1 Nonlinear Loads

• Fundamentals of Nonlinear Loads

• Fourier representation

4
1.2 Harmonic Phenomena

• Harmonics in voltage and current
• CAUSE Current
• Effect Voltage

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Examples of Harmonics I
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Examples of Harmonics II
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Examples of Harmonics III
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Harmonics versus Transients
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Power Factor

• Consider first a sinusoidal voltage and current

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RMS
In case of harmonics,
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Harmonic Phase Sequences

• In a balanced three-phase circuit
• the fundamental defines the positive phase
  sequence (or rotation) such as ABC or xyz or 321,
  and the 4th, 7th, 10th, , are also positive
  sequence
• the 2nd, 5th, 8th, 11th ,, are negative sequence
  (eg CBA)
• the 3rd, 6th, 9th, , are zero seq (all in phase)

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1
2 -
3 0
4
5 -
6 0
7
8 -
9 0
10
1
3 0
5 -
7
9 0
11 -
13
15 0
17 -
19
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Triplen harmonics

• Harmonic order h values that are multiples of 3
  are called triplen harmonics
• If the three phase circuit is balanced, the
  triplen harmonics are all in phase (zero
  sequence)
• triplen harmonic line currents will be additive
  at the neutral of a wye circuit by KCL (zero
  triplens if three-wire ungrounded wye or if
  delta)
• triplen harmonic line-line voltages will be zero
  by KVL

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Transformer
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Harmonic Indices

• Total harmonic distortion THD

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Harmonic Indices

• Total demand distortion TDD

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Harmonics Sources

• Conventional Sources
• Single-phase power supplies
• Fluorescent lighting
• ASD for HVAC and elevators
• Industrial Sources
• Power converters
• DC and AC drives
• Saturable devices

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4.1.1 SMPS
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4.1.2 Fluorescent lighting
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Power Converter