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Case Study

Case Study: Current Harmonic Compensation, Load Balancing and Neutral Current Compensation

Plant Performance without AHF Installed

A plant load current profile at one of our client locations is shown below. Following problems were noticed:

  • Highly distorted plant input currents
  • Dominant 3rd, 5th, and 7th harmonic currents
  • Large unbalance in three-phase currents
  • Large neutral current (61A, RMS)

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Figure: Plant input currents (AHF OFF)
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Figure: Phase-R current harmonic spectrum (AHF OFF)

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Figure: Phase-Y current harmonic spectrum (AHF OFF)
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Figure: Phase-B current harmonic spectrum (AHF OFF)

Plant Performance without AHF Installed
Parameter Phase - R Phase - Y Phase - B Neutral
Current (RMS) 218 A 170 A 172 A 61 A
THD (%) 12.4 % 16.8 % 17.7% -

Plant Performance with InstaSine i - Sine AHF Installed

With 3P4W i - Sine AHF installed at the above client location, an excellent improvement in the plant input currents can be noticed with the following observations:

  • Pure sinusoidal plant input currents
  • Negligible individual harmonic current levels
  • Balanced three-phase input currents
  • Neutral current down to single-digit value (from 61A to just 5A)

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Figure: Plant input currents (AHF ON)
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Figure: Phase-R current harmonic spectrum (AHF OFF)

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Figure: Phase-Y current harmonic spectrum (AHF OFF)
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Figure: Phase-B current harmonic spectrum (AHF OFF)

Plant Performance with AHF Installed
Parameter Phase - R Phase - Y Phase - B Neutral
Current (RMS) 163 A 163 A 161 A 5 A
THD (%) 2.0 % 1.9 % 1.7% -

POWER FACTOR (PF) IMPROVEMENT

Without AHF installed, poor true power factors and poor displacement power factors were noticed at the plant input side. However, when i - Sine AHF is installed, both true and displacement power factors are being maintained at 1.00 (ideal operating condition).


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