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Triol algorithm of Active Harmonic Filter (AHF)


Variable Speed Drives are the most-used products on the oil market. Triol VSDs have a wide range of functions and variations which make them the most flexible products for oil production. And now we’re going to talk about special VSD with Active Harmonic Filter.

This VSD is designed to improve the quality of consumed electricity, reduce the distortion of the sinusoidal shape of the current curves and the voltage of the network in the presence of a non-linear load of electrical installations. Triol AK06 with AHF has a unique control algorithm that has been implemented in order to achieve high network quality requirements and THD values of less than 5%. Since our company is an advanced manufacturer of electrical equipment, we strive to meet such high-quality standards as IEEE 519.

Operating with a standard VSD, there is a strong influence on the network due to higher harmonics. For the example pic. 1 and 2 show the current and the harmonic content in it.



The algorithm of operation for AHF is its brain center, which makes it possible to reduce the content of higher harmonics fundamentally.

Looking at pic. 3 and 4 you can get acquainted with the resultant current sinusoid and the harmonic composition in the work.



  1. The harmonics generated in the network cause various negative effects, namely:
  2. Overloading of generators, transformers, and motors;
  3. Distortion of supply voltage and, as a result, disturbance of the operation of sensitive devices;
  4. Resonance phenomena at frequencies of higher harmonics.

As a consequence, the consumer is facing a decrease of the equipment lifetime, additional losses, false alarms, and equipment shutdowns. Active Harmonic Filter allows to avoid or neutralize these phenomena. It is characterized by:

  1. Achieving the minimum distortion of current;
  2. Rapid response to changes in its harmonic composition;
  3. Providing the most effective interference suppression in the required frequency range;
  4. An increase in the speed and accuracy of calculating the instantaneous values of the canonical harmonics of the input current.

AHF management is based on supplying the network with the opposite values to the current distortion. The parameters of the operation are programmable and can be easily controlled both at the installation site and remotely.

Triol Corporation strives to offer electrotechnical market efficient high-quality equipment, and our aspiration is being successfully implemented. Check it out for yourself!

You can contact our specialists if you have any questions about the given topic, we will be glad to hear your comments!

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