29 research outputs found
Differential Flatness-Based Performance Enhancement of a Vector Controlled VSC with an LCL-Filter for Weak Grids
In this paper, a novel single-loop flatness-based controller (FBC) is proposed to control the grid-side current in a shunt converter connected to a weak grid through an LCL-filter. After its mathematical description, the paper reports controller implementation and some performance comparisons with two distinct implementations of the widely diffused vector current control approach, during balanced and unbalanced grid voltages, and weak grid conditions. Obtained results highlight higher tracking capability and better dynamic response of the proposed FBC. Moreover, because of its reduced negative conductance region, unstable behaviors that can be observed in weak grids appear significantly improved due to a reduced influence of the phase-locked loop system
Design and Control of Power Converters 2019
In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc
Control of modular multilevel converters in high voltage direct current power systems
This thesis focuses on a comprehensive analysis of Modular Multilevel Converters (MMC) in High
Voltage Direct Current (HVDC) applications from the viewpoint of presenting new mathematical
dynamic models and designing novel control strategies. In the first step, two new mathematical
dynamic models using differential flatness theory (DFT) and circulating currents components
are introduced. Moreover, detailed step-by-step analysis-based relationships are achieved for
accurate control of MMCs in both inverter and rectifier operating modes. After presenting these
new mathematical equations-based descriptions of MMCs, suitable control techniques are
designed in the next step. Because of the nonlinearity features of MMCs, two nonlinear control
strategies based on direct Lyapunov method (DLM) and passivity theory-based controller
combined with sliding mode surface are designed by the use of circulating currents componentsbased
dynamic model to provide a stable operation of MMCs in HVDC applications under various
operating conditions. The negative effects of the input disturbance, model errors and system
uncertainties are suppressed by defining a Lyapunov control function to reach the integralproportional
terms of the flat output errors that should be finally added to the initial inputs.
Simulation results in MATLAB/SIMULINK environment verify the positive effects of the proposed
dynamic models and control strategies in all operating conditions of the MMCs in inverter mode,
rectifier mode and HVDC applications.Esta tese visa proceder a uma análise abrangente de conversores multinível modulares (MMC)
para transmissão a alta tensão em corrente contínua (HVDC), almejando apresentar novos
modelos matemáticos em sistemas dinâmicos e projetar novas estratégias de controlo. Na
primeira etapa são introduzidos dois novos modelos matemáticos dinâmicos que usam
differential flatness theory e as componentes de correntes circulantes. Ainda, é estabelecida
uma modelação matemática para o controlo preciso dos MMCs, operando em modo inversor ou
modo retificador. Depois de apresentar as novas equações matemáticas, as técnicas de controlo
mais adequadas são delineadas. Devido às características não lineares dos MMCs, são projetadas
duas estratégias de controlo não-lineares baseadas no método direto de Lyapunov e no controlo
do tipo passivity theory-based combinado com controlo por modo de deslizamento através do
uso de modelos dinâmicos baseados em correntes circulantes para fornecer uma operação
estável aos MMCs em aplicações de HVDC sob várias condições de operação. Os efeitos negativos
das perturbações de entrada, erros de modelação e incertezas do sistema são suprimidos
através da definição da função de controlo de Lyapunov para alcançar os termos de integraçãoproporcionalidade
dos erros de saída para que possam finalmente ser adicionados às entradas
iniciais. Os resultados da simulação computacional realizados em ambiente MATLAB/SIMULINK
verificam os efeitos positivos dos modelos dinâmicos propostos e das novas estratégias de
controlo em todas as condições de operação dos MMCs no modo inversor, retificador e em
aplicações HVDC
Prädiktive Regelung und Finite-Set-Beobachter für Windgeneratoren mit variabler Drehgeschwindigkeit
This dissertation presents several model predictive control (MPC) techniques and finite-position-set observers (FPSOs) for permanent-magnet synchronous generators and doubly-fed induction generators in variable-speed wind turbines. The proposed FPSOs are novel ones and based on the concept of finite-control-set MPC. Then, the problems of the MPC techniques like sensitivity to variations of the model parameters and others are investigated and solved in this work.Die vorliegende Dissertation stellt mehrere unterschiedliche Verfahren der modellprädiktiven Regelung (MPC) und so genannte Finite-Position-Set-Beobachter (FPSO) sowohl für Synchrongeneratoren mit Permanentmagneterregung als auch für doppelt gespeiste Asynchrongeneratoren in Windkraftanlagen mit variabler Drehzahl vor und untersucht diese. Für die Beobachter (FPSO) wird ein neuartiger Ansatz vorgestellt, der auf dem Konzept der Finite-Control-Set-MPC basiert. Außerdem werden typische Eigenschaften der MPC wie beispielsweise die Anfälligkeit gegenüber Parameterschwankungen untersucht und kompensiert
Advances in Modelling and Control of Wind and Hydrogenerators
Rapid deployment of wind and solar energy generation is going to result in a series of new problems with regards to the reliability of our electrical grid in terms of outages, cost, and life-time, forcing us to promptly deal with the challenging restructuring of our energy systems. Increased penetration of fluctuating renewable energy resources is a challenge for the electrical grid. Proposing solutions to deal with this problem also impacts the functionality of large generators. The power electronic generator interactions, multi-domain modelling, and reliable monitoring systems are examples of new challenges in this field. This book presents some new modelling methods and technologies for renewable energy generators including wind, ocean, and hydropower systems
Advances in Modelling and Control of Wind and Hydrogenerators
Rapid deployment of wind and solar energy generation is going to result in a series of new problems with regards to the reliability of our electrical grid in terms of outages, cost, and life-time, forcing us to promptly deal with the challenging restructuring of our energy systems. Increased penetration of fluctuating renewable energy resources is a challenge for the electrical grid. Proposing solutions to deal with this problem also impacts the functionality of large generators. The power electronic generator interactions, multi-domain modelling, and reliable monitoring systems are examples of new challenges in this field. This book presents some new modelling methods and technologies for renewable energy generators including wind, ocean, and hydropower systems
Applications of MATLAB in Science and Engineering
The book consists of 24 chapters illustrating a wide range of areas where MATLAB tools are applied. These areas include mathematics, physics, chemistry and chemical engineering, mechanical engineering, biological (molecular biology) and medical sciences, communication and control systems, digital signal, image and video processing, system modeling and simulation. Many interesting problems have been included throughout the book, and its contents will be beneficial for students and professionals in wide areas of interest
Advances in Modelling and Control of Wind and Hydrogenerators
Rapid deployment of wind and solar energy generation is going to result in a series of new problems with regards to the reliability of our electrical grid in terms of outages, cost, and life-time, forcing us to promptly deal with the challenging restructuring of our energy systems. Increased penetration of fluctuating renewable energy resources is a challenge for the electrical grid. Proposing solutions to deal with this problem also impacts the functionality of large generators. The power electronic generator interactions, multi-domain modelling, and reliable monitoring systems are examples of new challenges in this field. This book presents some new modelling methods and technologies for renewable energy generators including wind, ocean, and hydropower systems