Control of three-phase converters for grid-connected renewable energy systems using feedback linearization technique

This paper presents a control algorithm based on feedback linearization technique for grid-connected three-phase non-dispatchable distributed generation (DG) systems such as a wind or a solar based generator. The power electronic interface is a voltage source inverter (VSI) and the output low-pass filter is an inductance (L) or an inductance-capacitance-inductance (LCL) circuit. The control objectives are injection of quality active power to the grid, regulation of the dc-link voltage, and regulation of reactive power to their desired values in the presence of system uncertainties and disturbances. Unlike the conventional methods which linearize the equations to design a controller working at the operating point, the proposed method of this paper is based on using a set of state variables which makes the equations globally linear for all operating points. Moreover, the method completely decouples the reactive-power and dc-link voltage control loops. The design stage is simple and engages no trial and error in adjusting the controller gains. Simulation results are also provided to confirm analytical derivations.