Danfoss AHF 010 Design Manual

Also see for AHF 005: Manual Operating instructions

Contents

Danfoss AHF 010 Design Manual Manual pdf 16 page image

1) New definitions are introduced through IEC/EN 61000-3-12:2011which means that. THD is replaced by THC/Iref.2) New definitions are introduced through IEC/EN 61000-3-12:2011which means that PWHD is replaced by PWHC/Iref2.3 Harmonic MitigationThere are several ways of mitigating the harmonics causedby the frequency converter 6-pulse rectifier, and they allhave their advantages and disadvantages.Selecting the right solution depends on several factors:• The grid (background distortion, mainsunbalance, resonance, and type of supply -transformer/generator).• Application (load profile, number of loads, andload size).• Local/national requirements/regulations (forexample IEEE 519, IEC, and ER G5/4).• Total cost of ownership (for example initial cost,efficiency, and maintenance).IEC standards are harmonized by various countries orsupra-national organizations. All above-mentioned IECstandards are harmonized in the European Union with theprefix “EN”. For example, the European EN 61000-3-2 is thesame as IEC 61000-3-2. The situation is similar in Australiaand New Zealand, with the prefixes AS/NZS.Categories of harmonic solutions:• Passive• ActivePassive solutions consist of capacitors, inductors, or acombination of the 2 in different arrangements.The simplest solution is to add inductors/reactors oftypically 3–5% in front of the frequency converter. Thisadded inductance reduces the number of harmoniccurrents produced by the frequency converter. Moreadvanced passive solutions combine capacitors andinductors in trap arrangement specially tuned to eliminateharmonics starting from, for example, the 5th harmonic.The active solutions determine the exact current thatcancels the harmonics present in the circuit andsynthesizes and injects that current into the system. Thus,the active solution mitigates the real-time harmonic distur-bances, which makes these solutions effective at any loadprofile. For more details on the Danfoss active solutions,refer to VLT® Low Harmonic Drive Operating Instructions andVLT® Advanced Active Filter AAF 006 Operating Instructions.Introduction to Harmonics a... VLT® Advanced Harmonic Filter AHF 005/AHF 01014 Danfoss A/S © 05/2019 All rights reserved. MG80C60222