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Über dieses Buch

Power electronics and variable frequency drives are continuously developing multidisciplinary fields in electrical engineering and it is practically not possible to write a book covering the entire area by one individual specialist. Especially by taking account the recent fast development in the neighboring fields like control theory, computational intelligence and signal processing, which all strongly influence new solutions in control of power electronics and drives. Therefore, this book is written by individual key specialist working on the area of modern advanced control methods which penetrates current implementation of power converters and drives. Although some of the presented methods are still not adopted by industry, they create new solutions with high further research and application potential.

The material of the book is presented in the following three parts:

Part I: Advanced Power Electronic Control in Renewable Energy Sources (Chapters 1-4),

Part II: Predictive Control of Power Converters and Drives (5-7),

Part III: Neurocontrol and Nonlinear Control of Power Converters and Drives (8-11).

The book is intended for engineers, researchers and students in the field of power electronics and drives who are interested in the use of advanced control methods and also for specialists from the control theory area who like to explore new area of applications.



Advanced Power Electronic Control in Renewable Energy Sources


Chapter 1. Introduction to Renewable Energy Systems

In this chapter, the state-of-the-arts developments of renewable energy are reviewed in respect to the installed power and market share, where wind power and photovoltaic power generation are the main focuses due to the fast growing speed and large share of installed capacity. Some basic principles of operation, mission profiles, as well as power electronics solutions and corresponding controls are discussed respectively in the case of wind power and photovoltaic power systems. Finally a few development trends for renewable energy conversions are also given from a power electronics point of view. It is concluded that as the quick development of renewable energy, wind power and PV power both show great potential to be largely integrated into the power grid. Power electronics is playing essential role in both of the systems to achieve more controllable, efficient, and reliable energy production—which is crucial for the cost reduction and spread use of renewable energies, because their fluctuated and unpredicted features are un-preferred for the operation of the power grid. Meanwhile there are also some emerging challenges and considerations in the renewable energy conversion system, calling for more advanced controls as well as configurations of power electronics converter.
Ke Ma, Yongheng Yang, Frede Blaabjerg

Chapter 2. Advanced Control of Photovoltaic and Wind Turbines Power Systems

Much more efforts have been made on the integration of renewable energies into the grid in order to meet the imperative demand of a clean and reliable electricity generation. In this case, the grid stability and robustness may be violated due to the intermittency and interaction of the solar and wind renewables. Thus, in this chapter, advanced control strategies, which can enable the power conversion efficiently and reliably, for both photovoltaic (PV) and wind turbines power systems are addressed in order to enhance the integration of those technologies. Related grid demands have been presented firstly, where much more attention has been paid on specific requirements, like Low Voltage Ride-Through (LVRT) and reactive power injection capability. To perform the functions of those systems, advanced control strategies are presented with much more emphasis on the LVRT operation with reactive power injection for both single-phase and three-phase systems. Other control strategies like constant power generation control for PV systems to further increase the penetration level, and the improvements of LVRT performance for a doubly fed induction generator based wind turbine system by means of hardware protection solutions are also discussed in this chapter.
Yongheng Yang, Wenjie Chen, Frede Blaabjerg

Chapter 3. Control of Grid Connected Converter (GCC) Under Grid Voltage Disturbances

In this chapter operation of a reliable control method of a Grid Connected Converter (GCC) under grid voltage disturbances is presented. As a GCC authors understand power electronic AC-DC converter with AC side filter and DC-link capacitor operating as an interface between the electrical grid and Active Loads (AL). At the beginning short introduction to selected grid voltage disturbances is given. Afterwards, the chosen modeling approach of a GCC is discussed and the example of passive components calculation are provided. In the next sections a brief review of a basic GCC control methods is described. A control method: Direct Power Control with Space Vector Modulation (DPC-SVM) is chosen for further development process. For the basic scheme of DPC-SVM special control modules for voltage dips and higher harmonics compensation are presented. Due to the development of new control modules and its integration with the classical DPC-SVM a new reliable (robust to selected grid voltage disturbances such as dips, higher harmonics) control method is proposed: Robust Direct Power Control with Space Vector Modulation (RDPC-SVM). The term “robust” in the name of proposed control refers to the fact that the RDPC-SVM method is expected to operate in an uncertain environment with respect to the system dynamics. This new control method can assure sinusoidal like and balanced AC current in extremely distorted grid voltage. Based on the case study from series 5–400 kVA of Voltage Source Converters (VSCs) it was verified that the control dynamic and features of the RDPC-SVM fulfill requirements of sinusoidal and balanced currents under uncertain grid voltage distortions. Moreover, the quality of current and power is significantly improved in comparison to classical methods. Hence, the negative impact of the GCC on the grid voltage (through its inner impendence) is significantly reduced i.e.: lower Total Harmonics Distortion (THD) factor of a grid current, control of active and reactive power flow assure good quality of integration with a grid even in case of increased impedance within operation limits.
Marek Jasiński, Grzegorz Wrona, Szymon Piasecki

Chapter 4. Faults and Diagnosis Systems in Power Converters

A power converter is needed in almost all kinds of renewable energy systems and drive systems. It is used both for controlling the renewable source and for interfacing with the load, which can be grid-connected or working in stand-alone mode. Further, it drives the motors efficiently. Increasing efforts have been put into making these systems better in terms of reliability in order to achieve high power source availability, reduce the cost of energy and also increase the reliability of overall systems. Among the components used in power converters, a power device and a capacitor fault occurs most frequently. Therefore, it is important to monitor the power device and capacitor fault to increase the reliability of power electronics. In this chapter, the diagnosis methods for power device fault will be discussed by dividing into open- and short-circuit faults. Then, the condition monitoring methods of DC-link electrolytic capacitor will be introduced.
Kyo-Beum Lee, Ui-Min Choi

Predictive Control of Power Converters and Drives


Chapter 5. Predictive Control in Power Electronics and Drives: Basic Concepts, Theory, and Methods

In this chapter we revise basic principles and methods of model predictive control with a view towards applications in power electronics and drives. The simplest predictive control formulations use horizon-one cost functions, which can be related to well-established dead-beat controllers. Model predictive control using larger horizons has the potential to give significant performance benefits, but requires more computations at each sampling instant to solve the associated optimization problems. For particular classes of system models, we discuss practical algorithms, which make long-horizon predictive control suitable for power electronics applications.
Daniel E. Quevedo, Ricardo P. Aguilera, Tobias Geyer

Chapter 6. Application of Predictive Control in Power Electronics: An AC-DC-AC Converter System

This chapter presents an application of predictive control in power electronics. The analyzed application is an energy conversion system from alternate current (AC) to direct current (DC) and to alternate current (AC) again. This example has been carefully selected because a number of predictive control principles can be clearly explained using this topology and later expanded to a wide variety of converter topologies. The chapter includes the mathematical models an a clear presentation of the control strategies. The results show that the use of predictive control introduces a conceptually different solution which allows for the control of electrical energy without using pulse-width modulation and linear controllers.
José Rodríguez, Haitham Abu-Rub, Marcelo A. Perez, Samir Kouro

Chapter 7. Application of the Long-Horizon Predictive Control to the Drive System with Elastic Joint

In the paper a robust Model Predictive Control structure for speed regulation of a drive system with an elastic transmission is proposed. A methodology for robust design based on suitable selection of the explicit form of MPC which enables the drive’s safety and physical limitations to be directly incorporated into control synthesis is presented. The simulation results show that the controller is very effective in regulating load speed for a wide-range of the changes of the load side inertia. The simulation studies are confirmed through a variety of experimental tests.
Krzysztof Szabat, Piotr Serkies, Teresa Orłowska-Kowalska

Neuro and Nonlinear Control of Power Converters and Drives


Chapter 8. Adaptive Neurocontrollers for Drive Systems: Basic Concepts, Theory and Applications

In this chapter basic principles of neurocontrol are revised and discussed from the point of view of applications in converter-fed drive systems. The main neural network structures used as neural controllers are presented and classified into two groups: off-line and on-line trained controllers. From the point of view of drive system uncertainties, caused by simplifying assumptions under mathematical model formulation, errors in drive parameters identification and changes of the models and their parameters under different operation conditions, on-line adaptive neural controllers are proposed. Various neural structures and their on-line training methods are discussed. The chosen neurocontrollers were verified in simulation and experimental tests for converter-fed drives with rigid and resilient mechanical connections between the driving motor and loading machine.
Teresa Orłowska-Kowalska, Marcin Kamiński

Chapter 9. Advanced Control and Optimization Techniques in AC Drives and DC/AC Sine Wave Voltage Inverters: Selected Problems

This chapter presents the application of a particle swarm optimization (PSO) to a controller tuning in selected power electronic and drive systems. The chapter starts with a relatively simple tuning of a cascaded PI speed and position control system for a BLDC servo drive. This example serves as the background for a discussion on selecting the objective function for the PSO. Then the PSO is used in two challenging controller tuning tasks. This includes optimizing selected learning parameters in the adaptive artificial neural network (ANN) based online trained speed controller for an urban vehicle (3D problem) and selecting penalty factors in the LQR with augmented state (i.e. with oscillatory terms) for a three-phase four-leg sine wave inverter (15D problem). It is demonstrated with the help of these case studies why and where the PSO, or any other similar population based stochastic search algorithm, can be beneficial. Engineers encounter many non-straightforward controller tuning problems in power electronic systems and this chapter illustrates that in some cases it is relatively easy to reduce these tasks into the objective function selection problem. The relevant controller parameters are then determined automatically by the PSO.
Barłomiej Ufnalski, Lech M. Grzesiak, Arkadiusz Kaszewski

Chapter 10. Space Vector Modulation in Three-Phase Three-Level Flying Capacitor Converter-Fed Adjustable Speed Drive

This Chapter is devoted to the Space Vector Modulation (SVM) in three-phase three-level Flying Capacitor Converter (FCC) fed adjustable speed drive (ADS). First, the classical and adaptive SVM are described. The adaptive SVM provides reduction of number of switching in the whole linear range of the converter operation because minimal number of vectors is used in each modulation region. As result, switching losses in FCC are reduced in comparison to the classical SVM and thus, the converter efficiency is increased. Next, elimination of DC sources unbalance in full range of operation of the FCC is presented. The minimization of the flying capacitors voltages pulsation is obtained by the compensation of flying capacitors voltages balancing delay based on prediction of those voltages values in next modulation period. Finally, taking to account the requirements of the demanding ASD application: low speed operation without phase current distortion and the high speed operation over the linear range of the converter with reference output voltage amplitude, the additional features for both modulation techniques: the dead-time effect and semiconductor devices voltage drop compensation as well as the overmodulation algorithm are shown.
Sebastian Styński, Mariusz Malinowski

Chapter 11. Some Aspects of Nonlinear and Discontinuous Control with Induction Motor Applications

In this Chapter the theory of nonlinear control systems is shortly described. The nonlinear feedback linearization control (FLC) and discontinues sliding mode control (SMC) are presented. Moreover, several applications of nonlinear control methods for induction motor drive are shown. The FLC guarantees the exactly decoupling of the motor speed and rotor flux control. Thus this control method gives a possibility to get very good behavior in both dynamic and steady states. The SMC approach assures direct control of inverter legs and allows using a simple table instead of performing complicated PWM calculation. Moreover the SMC is robust to drive uncertainties. The good behaviour of rotor flux and mechanical speed Sliding Mode Observers (SMO) is the important feature of the system. Therefore, presented approaches are very useful in a variety of applications and, in particular, in the drive systems and power electronics.
Dariusz L. Sobczuk


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