energies Article Simulation Studies of Control Systems for Doubly Fed Induction Generator Supplied by the Current Source Converter Pawel Kroplewski 1 , Marcin Morawiec 1, * , Andrzej J ˛ aderko 2 and Charles Odeh 3   Citation: Kroplewski, P.; Morawiec, M.; J ˛ aderko, A.; Odeh, C. Simulation Studies of Control Systems for Doubly Fed Induction Generator Supplied by the Current Source Converter. Energies 2021, 14, 1511. https://doi.org/10.3390/en14051511 Academic Editor: Oscar Barambones Received: 11 January 2021 Accepted: 5 March 2021 Published: 9 March 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Faculty of Electrical and Control Engineering, Gda ´ nsk University of Technology, 80-233 Gda´ nsk, Poland; pawel.kroplewski@pg.edu.pl 2 Faculty of Electrical Engineering, Czestochowa University of Technology, 42-201 Cz˛ estochowa, Poland; aj@el.pcz.czest.pl 3 Department of Electrical Engineering, University of Nigeria, Nsukka 410001, Nigeria; charles.odeh@unn.edu.ng * Correspondence: marcin.morawiec@pg.edu.pl; Tel.: +48-58-347-1176 Abstract: The control system for a Doubly Fed Induction Generator (DFIG) supplied by a grid- connected Current Source Converter (CSC) is presented in this paper. Nonlinear transformation of DFIG model to the multi-scalar form is proposed. The nonlinear control strategy of active and reactive power of DFIG is realized by feedback linearization. In the proposed control scheme, the DFIG model and CSI parameters are included. Two Proportional-Integral (PI) controllers are dedicated for the control of the respective active and reactive powers. The control variables are the dc-link input voltage vector and the angular speed of the inverter output current. The proposed control approach is characterized by satisfactional dynamics and provides enhanced quality of the power transferred to the grid. In the simulation, evaluation of the characteristic operating states of the generator system, correctness of the feedback linearization and the dynamics of active and reactive power control loops are studied. Simulation results are adequately provided. Keywords: Doubly Fed Induction Generator; wind power generation; current source inverter; nonlinear control; sensorless control 1. Introduction The trend in electric power generation distinctly shows a transition from using exclu- sively large-scale electric power plants based on traditional energy sources (e.g., coal, crude oil) to renewable energy generation systems, such a solar, hydro, and especially wind farms. Rapid exhaustion of traditional energy sources results in a hike in fuel prices and gross level of environmental pollution. These conditions set the direction for the development of renewable electrical energy sources. The electromechanical conversion of energy in such systems is carried out either by Permanent Magnet Synchronous Machines (PMSMs), Induction Generators (IGs), or Self- Excited Induction Generators (SEIGs). The main reasons for using Doubly Fed Induction Generators (DFIGs) as a variable-speed drive for wind turbines are: reduction of stress in the mechanical structure, acoustic noise reduction, and the possibility to control active and reactive power. Also, they have been widely adopted in wind energy conversion systems since the early 1990s because of the advancement and low-cost power electronic converters. The back-to-back converter in the rotor circuit is rated only to about 30–40% of the nominal turbine power. To get the maximum efficiency and produced power, the control system should choose an optimal working point [1,2]. Drive system designs with static power converters (CSIs) were popular in the 1970s and 1980s [3,4], the operational concept was based on the control ‘angle of advance’. In these circuits, thyristors were used as power switches. However, they had numerous disadvantages, such as a complicated auxiliary supply system for thyristor and long Energies 2021, 14, 1511. https://doi.org/10.3390/en14051511 https://www.mdpi.com/journal/energies