Abstract: Aiming at the deficiency that the traditional active power filter（APF）can only control the local

harmonic source，a harmonic active defense system（HADS）based on virtual harmonic resistance was proposed.

The principle of harnessing harmonics in distribution network by HADS was analyzed，the HADS simulation

model was established，and two control strategies of maximizing harmonic power and minimizing harmonic

distortion rate were proposed. An engineering prototype was developed for engineering demonstration application.

Theoretical and experiments prove that HADS can effectively reduce regional harmonic pollution and become one

of the regional harmonic control means under the novel power system.

      Key words: harmonic active defense system（HADS）；inverter；virtual harmonic resistance；power quality；

optimization of harmonic control