Current Deadbeat Predictive Control - Control of Power Inverters in Renewable Energy and Smart Grid Integration - page 257

17

Current Deadbeat
Predictive Control

As shown in the previous two chapters, PI controllers in the dq frame and PR controllers in
the

or abc frame can be adopted to track the reference set for the grid current so that the
power exchanged with the grid is regulated. They are able to track pure sinusoidal reference
currents without steady-state errors under balanced conditions. In this chapter, a deadbeat (DB)
predictive controller isdiscussed so that the grid currents can track the grid current references
within two sampling steps so that the dynamic performance is improved. The controller is
designed and implemented in the natural ( abc ) reference frame.

αβ

17.1 Control Structure
The block diagram of a current-controlled VSI in the natural ( abc ) frame with the DB predictive
controller is shown inFigure 17.1. Each phase current is independently controlled viaaDB
predictive controller, which takes the reference current, the grid current and the grid voltage
as inputs. The three-phase current references are generated from the dq current references I d
and I q

with a dq → abc transformation.

17.2 Controller Design
The basic idea of a DB controller is for the controlled variable to reach its desired value within
fixed periods of sampling. In inverter control, this iswidely employed, with the capability of
predicting the reference current and the grid voltage, to track sinusoidal currents (Buso et al.
2001; Habetler 1993; Holmes and Martin 1996; Kawabata et al. 1990, 1991; Kojabadi et al.
2006; Lindgren 1996; Lindgren and Svensson 1998; Mohamed and El-Saadany 2007, 2008b;
Wu and Lehn 2006; Zeng and Chang 2008). A DB predictive controller is able to provide a
fast dynamic response but it is sensitive to system uncertainties (Timbus et al. 2009; Zeng and
Chang 2005).