A non-standard adaptive control for shunt active power filter without current harmonic detection

Conventional control strategies, used in shunt active power filters (SAPF), employ real-time instantaneous harmonic detection schemes which are usually implemented with digital filters. This increases the number of current sensors on the filter structure which results in high cost. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance. Differently from the conventional control schemes, this paper proposes a non-standard control strategy which indirectly regulates the phase currents of the power mains. The reference currents of system are generated by the dc-link voltage controller and is based on the active power balance of SAPF system. The current control strategy is implemented through an adaptive pole placement control strategy integrated to a variable structure control scheme (VS-APPC). The V S-APPC uses the internal model principle (IMP) of reference currents for achieving the zero steady state tracking error. This forces the phase current of the system mains to be sinusoidal with low harmonics content. Experimental results are showing for determining the effectiveness of SAPF proposed control system.