Active harmonic filter (AHF)

Active harmonic filter (AHF)

Technical Principle

Active harmonic filter (APF/AHF) is new power electronic equipment which can dynamically filter harmonic with variable amplitude and frequency and compensate reactive power, it overcome the shortages of conventional LC filter and obtained the better compensation performances than passive filter.

The right diagram is schematic diagram of active harmonic filter (APF/AHF), where, V_s is AC power supply, nonlinear load is harmonic source, it generates harmonic and consumes reactive power. AHF system is composed of instruction current operational circuit and compensation current generation circuit, the instruction current operational circuit is mainly to detect current components in harmonic current and reactive power of compensation object, and the compensation current generation circuit generates equivalent compensation current with same amplitude and inverse polarity with harmonic current to filter harmonics according to instruction signal, the main circuit adopts PWM converter. 

AHF Functions

• Reduce harmonic distortion
• Improve power factor
• Reduce line loss
• Prevent neutral line from overheat
• Prevent power equipments from noise, overheat and vibration like motor, transformer etc.
• Prevent signal transmission equipments from data loss and interference
• Prevent measurement error caused by non-sinusoidal current and voltage.
• Prevent sensitive semi-conductive device from damage
• Prevent circuit breaker trip.
• Prevent capacitors from burn due to harmonic resonance
• Ensure safety of power system and reduce energy consumption

AHF Technical Features

• Can filter all kinds of harmonic currents
• Filtering capability >95% for aimed harmonic
• Traction level IGBT module, 20KHz switching frequency    
• Response time <10ms
• Single capacity up to 400A
• Suppress three-phase unbalance
• Conform to IEEE Std. 519-1992, GB/T 14549
• Can be used as harmonic source
• Apply closed-loop control, and ensure filtering accuracy
• Can set filtering mode and select harmonic filtering type
• Adapt automatically to impedance change of power network
• Can connect 690V system(CE/C-tick) and 600V system(cUL) directly
• Parallel connection, easy for filtering capacity expansion
• Modularized design, easy for maintenance
• Perfect protection functions
• Faults record and history inquire
• Support multiple communication protocols

Technical Parameters 

Factory Acceptance Test Platform 

We built the first-class high voltage and big capacity active harmonic filter test platform to realize Factory Acceptance Testing for whole machine before delivery.