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## Four-leg three-level converters for renewable energy. Analysis, modulation and control

### Marcin Sędłak

#### Abstract

This PhD dissertation presents solution of power electronics interface between renewable energy source (RES) and four-wire low voltage electrical grid using three-level four-leg flying capacitor converter (FCC). Such solution enables elimination of Dyn transformer commonly used with three-leg converter in situations when islanding with asymmetrical load is possible. Based on analysis and comparison of different control methods, the method of independent control of phase currents by use proportional resonant controllers in natural coordinates was proposed. Such method gives possibility to eliminate coordinates transformations and to reduce number of controllers. In Chapter 3 outer hierarchical control structure composed of four levels was proposed. The main assumption of presented structure was treating DC link of the converter as a DC microgrid supplied from four sources: three grid phases as three AC sources and RES as a DC source. This approach allows to regenerate voltage of phase which is at the moment lack in the grid and make supplying of local load more flexible. Besides of describe of each level, way to tune all of controllers was shown. Next chapters present simulation and experimental results obtained in steady and dynamical states with nonlinear and asymmetrical local load at different conditions of electrical grid. Finally, the conclusions and future research works are given.
Record ID
WUT4a01202b3a7d424f8edbdc6671d1ce74
Diploma type
Doctor of Philosophy
Author
Title in Polish
Czterogałęziowe przekształtniki trójpoziomowe dla energetyki odnawialnej. Analiza, modulacja i sterowanie
Title in English
Four-leg three-level converters for renewable energy. Analysis, modulation and control
Language
(pl) Polish
Certifying Unit
Faculty of Electrical Engineering (FoEE)
Discipline
electronic engineering / (technology domain) / (technological sciences)
Status
Finished
Start date
02-02-2012
Defense Date
16-12-2014
Title date
17-12-2014
Supervisor
Marian Kazimierkowski Marian Kazimierkowski,, Undefined Affiliation
Pages
227
Keywords in English
four-leg conventer,multilevel conventer,renewable energy sources,grid-connected conventer,flying capacitor conventer,power electronics interface,active filter
Abstract in English
This PhD dissertation presents solution of power electronics interface between renewable energy source (RES) and four-wire low voltage electrical grid using three-level four-leg flying capacitor converter (FCC). Such solution enables elimination of Dyn transformer commonly used with three-leg converter in situations when islanding with asymmetrical load is possible. Based on analysis and comparison of different control methods, the method of independent control of phase currents by use proportional resonant controllers in natural coordinates was proposed. Such method gives possibility to eliminate coordinates transformations and to reduce number of controllers. In Chapter 3 outer hierarchical control structure composed of four levels was proposed. The main assumption of presented structure was treating DC link of the converter as a DC microgrid supplied from four sources: three grid phases as three AC sources and RES as a DC source. This approach allows to regenerate voltage of phase which is at the moment lack in the grid and make supplying of local load more flexible. Besides of describe of each level, way to tune all of controllers was shown. Next chapters present simulation and experimental results obtained in steady and dynamical states with nonlinear and asymmetrical local load at different conditions of electrical grid. Finally, the conclusions and future research works are given.
Thesis file
• File: 1
Sedlak.pdf
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Uniform Resource Identifier
https://repo.pw.edu.pl/info/phd/WUT4a01202b3a7d424f8edbdc6671d1ce74/
URN
urn:pw-repo:WUT4a01202b3a7d424f8edbdc6671d1ce74

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