Finite Set Model Predictive Current Control of a Grid Converter Equipped with an LCL Filter

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master_Suman_Rishi_2017.pdf (2.07 MB)

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Sähkötekniikan korkeakoulu | Master's thesis
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Date

2017-03-13

Department

Major/Subject

Electrical drives

Mcode

ELEC3024

Degree programme

AEE - Master’s Programme in Automation and Electrical Engineering (TS2013)

Language

en

Pages

8+51

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Abstract

A grid converter is a critical component used to synchronize a renewable energy source with the utility grid and are also used as an active front-end rectifier for motor drives. Converter switching actions produce harmonics and therefore, it is equipped with an LCL filter to feed smooth sinusoidal current to the grid. However, the resonance behaviour of LCL filter amplifies the harmonics appearing at its resonant frequencies, therefore resonance damping is necessary. This thesis proposes a current controller based upon finite set model predictive control for current tracking and active damping of the LCL filter resonance. The current prediction for the controller is done in a small horizon window and the possibility to extend it to longer horizon has been explored. A hold equivalent discrete-time model with zero-order-hold assumption is used by the controller for predicting current for future time instants using the present state measurement. The current controller also uses an observer to enhance its disturbance rejection capability and reduce the need of additional sensors required to run the controller. The dynamic performance and robustness of the finite set model predictive current controller is demonstrated through simulation results.

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Supervisor

Hinkkanen, Marko

Thesis advisor

Song, Zhanfeng

Keywords

Current controller, disturbance rejection, finite set, LCL filter, observer, resonance damping

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https://urn.fi/URN:NBN:fi:aalto-201704133565

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[dipl] Sähkötekniikan korkeakoulu / ELEC