Harmonic detection and filtering - Schneider Electric

Solutions to attenuate harmonicsFigure 16 shows an example of an active filter compensating the harmonic current(I har = -I act).E95240Figure 16 - Operating principle of an active filter.The active filter injects, in opposite phase, the harmonics drawn by the load, suchthat the line current Is remains sinusoidal.6.2.3 Hybrid filtersb typical applications:v industrial installations comprising a set of devices causing harmonics with a totalpower rating greater than 200 kVA approximately (variable-speed drives, UPSs,rectifiers, etc.)v installations where power factor correction is requiredv situations where voltage distortion must be reduced to avoid disturbing sensitiveloadsv situations where current distortion must be reduced to avoid overloadsv situations where conformity with strict harmonic-emission limits is requiredb operating principle:the two types of filters presented above can be combined in a single device, thusconstituting a hybrid filter (see figure 17). This new filtering solution combines theadvantages of the existing systems and provides a high-performance solutioncovering a wide power range.E95241Figure 17 - Operating principle of a hybrid filter.34