APF Active Power Filter Active Harmonic Filter AHF

Item No.: 00163
Active harmonic filter is connected in parallel with non-linear loads, and uses one set of CT to detect the load current. It calculates each order harmonic current by FFT algorithms in its DSP microchips, and then generates a compensating current with the

Active Harmonic Filter(APF/AHF for short) is a perfect comprehensive solution to power quality problems with power grid such as harmonic wave(can filter 2nd to 50th harmonic interference completely), reactive power, and 3 phase load unbalance.

Active Harmonic Filter is connected in parallel in power grid, to detect the harmonic wave in power grid in real time, generate the -phase compensation current through the converter, and dynamically filter the harmonic wave in power grid. The operation of AHF is unaffected by power grid structure and load type, and it will not produce harmonic oscillation with the system, thus perfectly realizing harmonic wave control of various loads.

Active Harmoinc Filter can also realize dynamic reactive compensation, and control the capacitor switching, to improve the power factor of power grid. Meanwhile, AHF has the function of controlling the 3 phase load current unbalance, thus comprehensively solving various power quality problems with power grid.


active harmonic filter modular active harmonic filter modular
Active Harmonic Filter module Rack type AHF panel



Specification of AHF

Rated Voltage AC 308V-480V
Electric Connection   3P3W/3P4W
Rated Frequency     50Hz (60Hz) +/- 10%
Rated Current per Module 30Amp,50Amp, 75Amp, 100Amp,150Amp
Rated Current per Cabinet  30~600Amp (module combination)
Redundancy   Each module is an independent filtering system
Harmonic Elimination Range  2nd ~ 50th order (Selectable)
Compensation Mode Compensate Harmonics,Reactive Power,Phase imbalance
Harmonic Filtering Performance Filter up to 98% harmonics at rated load
THDv/THDi THDv<3%, THDi<5% after filtering
Reactive Power Compensation Capability  Both inductive and capacitive reactive power compensation
Imbalance Correction Capability  Mitigate negative and zero sequence
Full Response time  <5ms
Instant Response time <100us
Thermal Loss ≤3% of AHF rated capacity (kVA)



AHF principles

Active Harmonic Filter is connected in parallel with non-linear loads, and uses one set of current transformers (CT) to detect the load current. It calculates each order harmonic current , and then generates a compensating current with the same amplitude but opposite phase angles to the detected harmonic current, which cancels out the original load harmonics.
The AHF not only eliminates harmonic current from the load side, but it also mitigates harmonic voltage caused by harmonic currents. The AHF system can also improve power factor (PF) and correct load imbalances in the power system.

active Harmonic Filter Principle AHF Interface
Active Harmonic FIlter Principle Active Harmonic Filter Interface


AHF Benefits

Ultra-fast reactive power compensation(Inductive and capacitive).

Harmonic Compensation up to 50th harmonic(Individual selectable).

Load balancing between phases and unloaded neutral wire.

Flicker compensation.  

Reduce overheating/Redue nuisance tripping/Reduce overloading/ Reduce equipment failure.

Improve Reliability.    

Compact Design and Modular system.

Grid resonance detection.

User-friendly HMI menu operation.

Ethernet and ethercat system for interconnection.

High performance and reliability.

Insensitive to network/grid condisitons.

Simple installation.


apf svg assemble line  APF SVG Aging and reliability test
APF SVG Assemble line  APF SVG Aging and reliability test



AHF application


■Industrial installations with a set of non-linear loads representing more than 500kVA (variable-speed drives, UPSs, rectifiers, etc.)

■Installations requiring power-factor correction.

■Installations where voltage distortion must be reduced to avoid disturbing sensitive loads

■Installations where current distortion must be reduced to avoid overloads

Following are typical application industries of Active Harmonic Filter. 


active harmonic for crane and conveyor system active harmonic filter for solar power plant active harmonic filter for oil and gas industry active harmonic filter for electric arc furnace and metling furnace
active harmonic filter for water and wasted warter treatment active harmonic filter for wind and pv power farm active power filter for primary elements industry

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