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Active Harmonic Filter

i -Sine is trademark name for the Active Harmonic Filter (AHF) developed and manufactured at InstaSine. The i -Sine AHFs are equipped with newest generation IGBTs that are intelligently controlled using Artificial Neural Network (ANN) based architecture. Our AHF is most advanced and effective power quality improvement solution to mitigate harmonic, unbalance, and reactive currents.

i -Sine AHFs are capable to perform:

  • Harmonic currents mitigation in phase currents
  • Reactive Current mitigation in phase currents (i.e. power factor correction)
  • Negative Sequence Currents Mitigation (balancing three-phase load currents)
  • Zero sequence current mitigation (Neutral current mitigation, using 3P4W AHFs)
  • Transformer HT side power factor correction while connected at LT side.

Compensation Philosophy

  • i -Sine AHF identifies the downstream load current composition (such as, active, reactive, harmonics and unbalance components) using intelligent artificial neural network (ANN) based control technique and cancels the unwanted components at the load end through precise control of IGBTs.
  • Based on the selective harmonic compensation, i -Sine AHF computes the magnitude of individual harmonic, fundamental reactive and unbalanced current that are to be compensated.
  • As long as the compensation requirement is within the rating of i -Sine AHF capacity, it compensates all the unwanted current components. In case the requirement is higher than its rated capacity, compensation current is dynamically limited to i -Sine AHF capacity using inbuilt real-time current limiting algorithm.
  • Thanks to our closed-loop adaptive ANN control philosophy, i -Sine AHF dynamically compensates the unwanted components of load current even when the load changes frequently.
Active Harmonic Filters

i -Sine AHF Features
Harmonic Mitigation: i -Sine AHF accurately maintains the plant current THD to stay below the limits specified by the IEEE 519-1992 with full dynamic compensation.
Power Factor Control: i -Sine AHF ensures unity power factor operation of the plant. Fully dynamic compensation adaptive to the load changes.
Current Balancing: i -Sine AHF assures the plant current drawn from the EB to be balanced and sinusoidal.
Neutral Current Compensation: A 3P4W i -Sine AHF fully supports the load neutral current locally and assures zero neutral current on the source/EB side.
Long-lasting: To prevent i -Sine AHFs from most common DC link capacitor failure problem, the DC link is realized using film capacitors with an operational life greater than or equal to 1,00,000 hours.
Designed for harsh weather conditions: Designed to operate at 50oC ambient temperature without any deration. PCBs are applied with con formal coating for improved reliability.
No over sizing: i -Sine AHFs are designed to compensate the harmonic current with peak magnitude of 2.2 times the RMS current (continuous rating). Therefore, our units do not require over sizing for the high peak current loads.
No prerequisite: i -Sine AHF in general, does not require the installation of input chokes with VFDs, as long as the load current THD is below 40%.
Wide Range of Harmonics Selection: i -Sine AHFs cancel all the odd harmonics up to 71st order. Further, these harmonics are individually selectable without any limit on the number of harmonics selections at a time.
Best-In-Class Energy Efficiency: i -Sine AHF consists of an intelligent On-The-Fly real-time internal switching loss minimization technique to enhance the converter energy efficiency. Additionally, the state-of-the-art LCL based third order filters reduce the filtering losses as well.
Optimum Design: Light in weight, compact in size, quieter in operation while delivering best-in-class performance.
Integrated Best-in-Class HMI: i -Sine AHFs have integrated 7-inch TFT touch-screen display to visualize/set the AHF and plant parameters. Moreover, the user can observe the real-time three-phase voltages and currents (load /AHF/source side) wave forms just like an oscilloscope.
In-house R&D and manufacturing with better service: The research, development, and the manufacturing activities are fully carried out by InstaSine. This certainly ease our team in providing the guaranteed service even after the end of warranty period.

i -Sine AHF Benefits

  • Close to pure sinusoidal plant current (enhanced power quality)
  • Compliance to power quality standards, such as, IEEE 519-1992 & IEEE 519-2014, and CEA harmonic limits.
  • Stay protected from upcoming harmonic penalties by electricity distribution companies.
  • Unity power factor operation (saving in electricity bill as per the state board tariff/schemes)
  • Reduced energy losses with improved plant efficiency 
  • Reduced plant down times from the nuisance tripping due to harmonics
  • Restored ability of existing electrical infrastructure to operate at full-load capacity
  • Improved plant equipment life with reduced maintenance cost.

i -Sine AHF Specifications
Plant Input Conditions
System Voltage (RMS) 350 - 450 V
Fundamental Frequency (Hz) 50 ± 5%
System Configuration 3P3W and 3P4W (single-phase option available)
Product Specification
Power Semiconductor Devices IGBTs
Output Current Ratings (RMS) 25A/ 50A/ 100A/ 150A/ 200/ 300A
Continuous Peak Compensating Current Rating 2.2 times RMS Value “No need of oversizing with VFD loads”
Harmonic Compensation Range All odd harmonics up to 71st order “Widest range and fasted harmonic filtering available in India”
Selective Harmonic Compensation From 0 to 100% for all 71 Harmonics “No limit on the number of harmonics selection at a time”
Reactive Power Compensation Yes
Harmonic Attenuation Factor More than 97% at rated load
Load Current Balancing Yes
Cooling Forced Air Cooling
Cable Entry Bottom
Mounting Wall mounting/ Floor mounting
i -Sine AHF Control System
Controller type Digital control
Control Method Based on Adaptive Artificial Neural Networks (ANN) “Ultra-fast computation”
Dynamic Response Time 100 microseconds
User Interface
Monitoring (Waveform and Parameters) Through InstaVIEW software on USB port
User Parameter Setting Using InstaVIEW software
Additional Details
Operating Temperature Range 0 to 50o C “No derating required in the entire operating range”
Active Power Loss Less than 3%
Parallel Operation Yes
Short-circuit Protection Yes
Color Standard
Noise Level 65dB

*Note: Custom designs are available on request.


i -Sine AHF Sizing
Plant Harmonic and Reactive Current Calculations
The i -Sine AHF should be sized properly to compensate both the harmonics and fundamental reactive currents simultaneously. Following procedure can be used to compute the requiredi -Sine AHF rating. The knowledge of three basic parameters required to size the i -Sine AHF are:
Parameter Symbol
Total RMS current drawn by the plant at full load I rated
Total current harmonic distortion at full load THDi*
Fundamental power factor (either leading or lagging) PF
* Absolute value (i.e., percentage/100).
Once the above parameters are known, the plant total harmonic current (IH) in amperes can be calculated as: $$IH = Irated { \sqrt{{THDi^2} \over 1 + THDi^2}}$$
While, the plant total fundamental reactive current (IQ) in amperes can be determined as: $$IQ = Irated { \sqrt{{1- THDi^2} } \sqrt{ 1 - PF^2}}$$
i -Sine AHF Rating Selection
The RMS current rating (IF) of i -Sine AHF can be selected as per the compensation requirement.
Purpose of AHF i-Flex AHF Rating in Amperes (RMS)
Harmonics Cancellation Only
Compliant to EB harmonic requirements (or IEEE standards, such as, IEEE 519-2014)		 $$IF = IH $$
Unity Power Factor Operation Only
For maximizing power factor incentives only 		$$IF = IQ $$
Simultaneous Harmonics Cancellation and Unity power Factor Operation Compliant to EB harmonic requirements and power factor incentives $$IF = { \sqrt{{I^2H + I^2Q} } }$$

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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