Active harmonic filters (AHFs/APF) are typically stand-alone devices that reduce the high levels of harmonics produced by energy efficient non-linear loads. They work by injecting harmonics into the electrical system in equal and opposite measure to the existing system harmonics. As previously mentioned, harmonic filters are used to eliminate harmonic distortion caused by excess currents in and out of appliances. It can prevent large quantities of harmonics from causing damage to equipment, downtime of operation, and preventing an increase in operating costs.
The Active power filter monitors the load current real-time through the external current transformer CT, and extracts the harmonic component of the load current through the internal DSP computing, then sends it through the PWM signal to the internal IGBT, the inverter produces a current equal to the load harmonic and opposite to the harmonic direction and injects the current into the grid to compensate the harmonic current realizing the function of harmonic control.
System Parameters
Rated input wire voltage
380V (-15% ~ +20%)
Grid frequency
50 / 60 Hz (range: 45Hz ~ 62Hz)
Number of parallel machines
1 ~ 10 sets
Overall efficiency
≥97%
Grid structure
Three-phase three-wire / three-phase four-wire
Current transformer
150/5 ~ 10000/5
Circuit topology
Tri-level
Performance Index
Response time
<15ms
Scope of compensation
From -1 to 1, capacitive and inductive continuity is adjustable
Cooling mode
Intelligent air cooling
Noise index
<56dB
Frequently Asked Questions (FAQ)
What is an Active Harmonic Filter (AHF/APF)?
An Active Harmonic Filter (also known as an Active Power Filter) is a power electronics system designed to dynamically monitor and cancel out harmonic currents produced by non-linear loads in industrial or commercial power distribution systems.
How does the compensation current generation work?
The filter uses external Current Transformers (CT) to detect grid currents in real-time. An internal Digital Signal Processor (DSP) calculates the harmonic signals and controls high-speed IGBTs via Pulse Width Modulation (PWM) to output compensation currents that are equal and opposite to the load harmonics.
What are the benefits of installing an Active Power Filter?
Installing an APF helps protect sensitive electronics from damage, reduces power losses, minimizes system downtime, improves energy efficiency, prevents neutral line overheating, and avoids penalties from local utility companies for high harmonic distortions.
How many filter modules can be connected in parallel?
The system supports high scalability, allowing 1 to 10 sets of modules to run concurrently in parallel to handle larger electrical loads and expansion needs.
What is the response time and overall efficiency?
The system responds dynamically to changes in load harmonics in less than 15ms. Additionally, the system achieves a highly efficient operation rating of 97% or greater.
Sowest Electric
