Controle digital com malha dupla de tensão aplicado a um conversor formador de rede

Abstract

This dissertation presents a study on a grid-former converter (GFC) which is a part of a Power-Hardware-in-the-Loop (PHIL) structure. The PHIL will be used to verify the impacts caused by the integration of photovoltaic (PV) generation systems into grid, as well as to study the PV operation under grid disturbances. The GFC, composed by a two-level voltage source converter with a LC output filter, is responsible to feed isolated loads emulating an electrical grid. The modeling of the grid-former converter is done in the stationary frame (αβ0), providing a set of differential equations that describes the dynamical behavior of the system. The converter is controlled in voltage mode by means of the space vector modulation (SVM) strategy. Two control loops are designed to control the static converter. At the inner loop a novel discrete-time active damping technique is proposed in order to damp the filter resonance without the need of current feedback. The method is based on an inner feedback loop with digital lead compensator on the feedback path while the external loop uses a discretetime integrator and a modified digital resonant controller to guarantee a decreasing frequency response and ensure the quality of the voltage waveform at the point of common coupling, respectively. The resonant controllers are connected in series and the design is based on its zeros damping. Experimental results obtained with the prototype, which controllers were implemented in a Texas Instruments TMS320F28335 are used to validate the proposed control strategies.