A complex notch filter based approach to device the control strategy for a generalized unbalanced grid connected distributed generator

In this paper, a p-q theory based approach, using Complex Notch Filter, is proposed to control active and reactive power flow of a distributed generator connected to a generalized unbalanced grid. The proposed method facilitates high bandwidth grid power flow control along with maintaining sinusoidal grid currents by finding suitable inverter current references directly in the a-b-c frame. The proposed method is faster than the conventional methods because of the absence of the Phase Lock Loop and Park´s transformation requirement. A novel method of extracting the phase angle of the fundamental grid voltage is proposed. A Complex Notch Filter based method for extracting positive and negative sequence components together with filtering grid voltage harmonics is also proposed to reduce the computational burden on the processor. The method is devised for a generalized three-phase system. The proposed method is validated through rigorous tests and experimental results presented depict the efficacy of the proposed method.