Active harmonic filters

Many electrical loads in industrial applications, e.g. rectifiers, variable speed drives, welding equipment, but as well in office buildings, commercial buildings, infrastructure buildings draw non-sinusoidal currents from the grid. Non-sinusoidal currents lead to network perturbation, commonly called harmonic voltage distortion (THD-V), i.e. grid pollution of the power quality.

Cnsequences of excessive harmonic current loading

  1. Additional thermal losses in cable, neutral conductor, distribution panels, switchgear and transformer

  2. Distortion of the voltage wave form, excessive THD-V, power quality problems
  3. Unsymmetrical grid load

  4. Faster wear out of electrical distribution equipment and electric as well as electronic loads

  5. Massive overload of electricity supply and in worst case resonance conditions and consequently destruction and in worst case fire damage

  6. Resonance
  7. exploded capacitors

Solution

Passive PFC systems are only capable of compensating a few selected harmonics. Depending upon the network conditions, passive PFC systems tend towards resonance and can become overloaded.

Janitza active harmonic filters of the AHFI-series overcome the problems of conventional PFC and passive filters by means of latest power electronic solution, i.e. instead of shunt PFC capacitors the harmonics will be generated in an electronic way. AHFI active harmonic filters can independent of the harmonic order suppress, or better compensate, all harmonics up to the 49th order, i.e. 2450 Hz. Janitza’s active harmonic filters actively eliminate the harmonics present in the supply system – "cleaning” the network from harmonics.

Application

Active harmonic filters are primarily used in applications in which no or only limited additional capacitor load is allowed to install due to high existing power factor, in order to avoid over compensation, or in cases in which the harmonic distortion is excessively high. Other typical fields of application are high neutral conductor currents due to unbalanced systems or high third and tripplen harmonic currents, e.g. large number of single phase loads, (IT, data centre, large office buildings, banks, commercial buildings …)

Typical applications

  • IT and data centre

  • Oil and gas industry

  • Banks and insurance enterprises

  • Ski lifts

  • Office buildings

  • UPS equipment

  • Semiconductor industry

  • Steel industry

  • Automotive industry

  • Plants with continued processes