Control of grid converters for PV array excited wind-driven induction generators with unbalanced and nonlinear loads

• Composite power control model developed with combination of VOC and DPC.
• Unbalanced nonlinear load compensation for grid connected for PV–IG system.
• State space model for grid connected hybrid scheme in DDSRF.
• Reduction of induction machine de-rating with the proposed control.
• Active and reactive power control with maximum power extraction from PV.

In this paper, a new control algorithm for grid connected inverter fed by Photovoltaic array (PV) excited wind-driven induction generator (IG) for unbalanced nonlinear load at point of common coupling (PCC) is proposed. The proposed composite power controller comprises of multi control loops such as power, voltage and current loops. The power control loop generates positive sequence reference current based on the availability of PV power and the average power demand of the load and negative sequence reference currents to compensate the oscillating power component that appears due to the unbalanced nonlinear load at the PCC and further, drop due to non-fundamental power component is compensated by addition of virtual non-linear impedance to the current control loop. The voltage control loop generates the reactive current reference to compensate the drop due to nonlinear magnetizing reactance of IG to eliminate the machine de-rating effect. The current control loop regulates the average and suppresses the oscillating power in dual decoupled double synchronous reference frame to generate modulating signal to the PV sourced inverter. Exhaustive simulations are carried out for the proposed scheme for varying irradiations, wind speed and load variations at the PCC in MATLAB and compared with direct power control scheme.