Design and analysis of frequency adaptive Generalized Integrators for Active Power Filters

Generalized Integrator (GI) used in current control for Active Power Filters (APF) can achieve zero steady-state error for concerned harmonics compensation. This paper presents a controller, based on an array of frequency adaptive GIs, each one for a couple of harmonics, implemented in synchronous reference frame in order to reduce the overall computational effort. In order to eliminate the unexpected loss of gain and mismatch during discretization process, the design work has been directly done in the discrete-time domain. And the frequency adaptive strategy is realized through the use of a special phase-locked loop, thus ensure the good closed-loop performance in spite of the possible grid frequency variation. The experimental results confirm the superiority of the proposed scheme.