Autonomous Wind-Generated Electricity for Induction Motors

Depleting fossil fuels and concerns about global warming have forced a paradigm shift towards renewable energy resources in meeting our energy requirements. Wind energy utilization has been growing at a rapid rate fuelling research and development in high power wind turbines. To advance research and education in wind energy conversion systems, a controlled test bed is necessary that does not depend on wind availability. In this paper, a control structure is proposed to emulate high power, large inertia wind turbines using low power, small inertia machines. Majority of the existing methods for wind turbine emulation employ DC or induction motors with torque compensation loop. However, it suffers from noise and instability issues. DC motors have several disadvantages compared to induction machines in terms of cost, maintenance, speed and ruggedness, even though their control is simple. Hence, in this paper, Squirrel Cage Induction Machine (SCIM) in speed controlled mode is employed for emulation. The performance of the control structure is demonstrated through an experiment involving step change in wind velocity, where the dynamics of a high inertia wind turbine system are emulated. Simulations and experiments are conducted on a 7.5 kW Doubly Fed Induction Generator (DFIG) driven by a 5.5 kW SCIM, emulating a wind turbine.

There are several types of motors to choose from when selecting motors for large HP (2000 HP - 10.000 HP) cement plant applications including; squirrel cage induction motors, wound rotor induction motors, PAM induction motors, synchronous motors, and DC motors, all of which have their own advantages and disadvantages. This paper will compare the operational characteristics of the induction, synchronous and DC motors to demonstrate how to apply the different speed-torque-current characteristics of each when driving typical cement plant loads. This paper will compare several different starting methods for AC motors such as across the line starting, autotransformer, solid state starting, and Adjustable Speed Drive (ASD) and discuss the limiting factors of each method such as starting current requirements and cage heating. A comparison of the operating characteristics of induction and synchronous motors will demonstrate how the power factor and efficiency advantage of synchronous motors can be applied to lower the energy cost of a cement plant. The variable speed operation of induction and synchronous motors operating on adjustable speed drives will be compared with the operational characteristics of DC motors which vary speed without the use of a drive.

In this paper, the transient and steady-state performances of an isolated self-excited induction generator driven by a wind turbine and feeding power to a dynamic load such as a three-phase induction motor are analyzed. Mathematical modeling and simulation study of the whole system, including the wind turbine, induction generator, capacitor, pulse width modulated voltage source inverter, and dynamic load, are carried out with closed-loop voltage and frequency controller. The complete system is modeled in the stationary $d-q$ frame and validated by comparing simulation and experimental results at no-load. The same mathematical model is then used to study the transient performance of the self-excited induction generator supplying to a dynamic load. When the induction motor is connected to the induction generator without any voltage and frequency controller, it causes severe transients in electrical and mechanical variables of the generator. Due to the large starting-current requirement of the induction motor, there is a collapse of the terminal voltage of the generator. A bidirectional pulse width modulated source inverter with DC link battery is connected with the generator and operated in closed-loop control mode to maintain voltage and frequency and to operate the induction motor successfully with variable wind speed and mechanical load.

SummaryCurrently, a maximum power point tracking (MPPT) unit implemented in a wind energy conversion system (WECS) extracts the maximum mechanical power from the wind turbine used in the WECS. Therefore, the MPPT unit acts as a maximum mechanical power tracker (MMPT) that performs optimal control of the wind turbine to extract the maximum mechanical power from the wind turbine. In this paper, the basic concept of a maximum electrical power tracker (MEPT) is presented both theoretically and technically. It is demonstrated that an MEPT implemented in a WECS maximizes the output electrical power of the WECS. Thus, in contrast with an MMPT, the proposed MEPT optimally controls the whole of the WECS, rather than the wind turbine, to extract the maximum electrical power from the WECS. Since, in the WECS, the power efficiency of the whole of the WECS, not the wind turbine, should be maximized to extract the maximum output electrical power from the WECS, the conventional MPPT unit acting as an MMPT should be replaced with the proposed MEPT, and this is the superiority of the proposed MEPT to an MMPT or a conventional MPPT unit. To provide experimental verifications, 2 novel MEPT and MMPT with simple structures and better performance compared to the MPPT techniques commonly used in WECSs have been constructed, which are presented in detail.

In recent years, AC induction motors have replaced DC motor. The most important reason for this is that DC motors have a mechanical brush and commutator system that is subject to wear and tear over time. While DC motor drivers need a lot of maintenance due to this system, induction motors do not require almost any maintenance since this system is not available. In recent years, technological advances in the field of multiphase induction motors have led to a significant evolution. A lot of research has been done around the world and a lot of new and interesting developments have been reported to the literature. This paper provides information about six-phase induction. In addition, what kind of advantages the concept of multiphase provides and how this structure is formed contains information about them. The six-phase induction motor will be simulated through the MATLAB/SIMULINK package program and compare with three phase induction motor. Both motors were run in simulation using the same parameters. At the end of the simulation, current, moment and speed graphs of the six-phase induction motor and three-phase induction motor will be drawn according to time. The study also included equations used during modeling and equivalent circuits belonging to a six-phase induction motor. It has been graphically shown that a six-phase induction motor is more advantageous than a three-phase motor. For example, in six-phase induction motors, the transition time to a continuous state is shorter. In addition, while the frequency of torque vibration increases, its amplitude decreases, the current value of each phase decreases, the stator copper losses are less than the three-phase induction motor. In motors, usually the power needed is divided by the number of phases. So the more phases there are, the greater the power carrying capacity. Today, multi-phase induction motor drives are used in special applications such as electric vehicles, space technology, aerospace applications, as moving power on ships, electric trains, which require high reliability and power.

The conventional method of a single phase induction motor windings design usually constructed the main and auxiliary windings in both slot. So, there was a complicated winding design if that compare to the three-phase induction motor. Because of that, this study was aimed to design a new windings design of a single phase induction motor that construction like a three-phase induction motor. This study was focused to design a 24 slot capacitor-start capacitor-run induction motor. The windings in the motor are divided in 3 group like a three-phase induction motor. The two windings act as a main windings and the other winding act as auxiliary winding. The current rating of the winding of the proposed single-phase induction motor was 2.74A. The performances of the proposed method were compared with the performances of a three-phase induction motor that had the same current rating. The motor used as a comparator was a three-phase induction of 380/220V, 2.74/4.7A, Y/Δ, cage rotor, 4 poles, 1.5 HP, 1400 RPM, 50Hz. The result of this study showed that the proposed design of single phase induction motor could be operated with better performances than the three-phase comparator induction motor’s.

Conventional wind energy conversion systems (WECS) typically employ rotor side synchronous frame current control strategies to regulate the active/reactive power supplied by the WECS generator. Such strategies require accurate information regarding the rotor position and speed in order to set the dq frame reference currents and to perform the necessary frame transformations. This information can be obtained using a rotor speed sensor (i.e. a shaft encoder) or via a sensor-less strategy in which a dynamic machine model and stator current measurements are used to estimate the true rotor position. This paper now presents an alternative approach to control the active/reactive power supplied by the WECS permanent magnet synchronous generator (PMSG). The proposed strategy uses the three phase converter modulation commands to identify the phase and frequency of the PMSG stator terminal voltages. This enables the direct regulation of the real and reactive power extracted at the PMSG terminal voltages using a stationary frame Proportional + Resonant (PR) stator current regulation strategy, without requiring precise knowledge of the rotor position. Maximum power point tracking (MPPT) functions are realized using the measured PMSG terminal voltage frequency to form an estimate of the rotor speed. The result is a simple robust WECS control strategy that rapidly and accurately tracks rotor speed changes caused by wind speed variations. Detailed simulation and experimental results obtained for a scaled laboratory prototype system are presented to validate the proposed strategy.

In this paper, a Wind Turbine Emulator will be designed, developed and built. During this phase of the project, the experimental implementation of the Wind Turbine Emulator (WTE) for Wind Energy Conversion Systems (WECS) would consist of separately-excited DC motor. The DC motor is controlled by regulator hysteresis. The model of the wind turbine and the control of the DC motor, which emulate the wind turbine, are implemented in MATLAB/Simulink. The developed WTE allows a WECS to be analyzed or reconfigured for design studies without need of real wind turbines. The DC Motor and its control actuate as the WT. The proposed approach was implemented on DS1104 real-time interface card and Matlab/Simulink real-time control programming. The experimental results verify the performance of proposed WTE.

Small wind turbines are becoming an attractive solution for household applications. These micro generation units can be used as standalone applications or grid connected applications. However to get the full potential benefits of these wind turbines, systems should be low cost and reliable. Introducing the wind speed and rotor speed sensors at the generator shaft may reduce the reliability of small wind turbines. In this study, a grid connected sensor-less 5 kW small wind energy conversion system has been studied. The maximum power point tracking method of the wind turbine is totally independent from wind speed and rotor speed measurements. Optimum rotor speed and actual rotor speed are estimated using output current and voltage of the generator. To estimate the optimum rotor speed of the wind turbine, power signal feedback method has been used. Moreover, a sliding-mode observer is designed to estimate the rotor speed. Performance of the sliding-mode observer system has been compared with the measured rotor speed based wind energy conversion system. The simulation results show the effectiveness of the proposed sensor-less control system for the system under consideration.

The purpose of the implementation of this study were: (a) Determine the amount of air flow rate of air flow out of the exhaust pipe, (b) Identify the influence of wind speed in the free air against air flow out from the exhaust pipe, (c) Determine the amount of electrical power and energy potential that can be generated, and (d) Identify the feasibility of the utilization of exhaust airflow for WECS development. This research method begins with the collection of primary data, the direct measurement of natural wind speed and exhaust airflow velocity. Secondary data is mainly drawn from the data specification wind turbine selected unit. Subsequent calculation of the relevant variables, such as: electrical power, electrical energy and power coefficient of the rotor. Analysis and discussion focused on finding interplay between measurable variables. From the research, it can be concluded: (a) Exhaust air flow rate contained in the research area, starting a low of 3.92 m/s which is located at a point 15 meters from the source to a high wind reaches 19, 88 m/s which is at a point 3 feet from wind sources. (b) The amount of exhaust air flow rate has a significant effect on the power and potential of electrical energy that can be generated by a wind turbine mini scale, (c) The most important factors that influence the selection of a wind turbine in WECS is the air flow velocity at the local site and rotor power coefficient of each alternative wind turbine. The higher the coefficient of the rotor of a wind turbine, the higher the efficiency of the wind turbine, and (d) The potential airflow considerable waste has yet to be directly used as WECS, but first must be adjusted for the height of the exhaust pipes to achieve the required height.

THE interest in autonomous alternative energy systems is increasing as conventional fuels are depleted. Many agricultural stationary loads are located where electric utility power is not presently available and is not economically feasible to install. Irrigation water pumping is an example of a remote, high energy use that needs an autonomous power source. A wind turbine with a permanent-magnet alternator was used to produce variable-voltage, variable-frequency output to power a standard three-phase, induction motor in a stand-alone pumping system. The variable-speed alternator produced power with a frequency of 30 to 65 Hz and a voltage from 81 to 210 V, resulting in a voltage to frequency ratio that varied from 2.7 to 3.2. Combined pump and motor efficiencies varied from 37 to 54%, nearly equivalent to those obtained with utility power. The system operated in windspeeds above 3.5 m/s. We found this wind energy conversion system capable of providing power to satisfactorily pump water in a stand-alone system.

The focus of documented research in this paper is the Low Voltage Ride Through (LVRT) capability of electric grid connected Wind Energy Conversion System (WECS) using Takagie-Sugeon (TS) type fuzzy controller. The increased deployment of Wind Turbine technology in modern power systems makes the LVRT capability of WECS one of the important research topics. Consequently, to avoid power network instability, power utilities defined technical specifications for modern WECS. These specifications are known as Grid Codes and are further categorized as static and dynamic requirements. The LVRT capability falls under the category of dynamic requirements of Gird Codes. The most frequently and extensively used generator for wind turbines is the Doubly Fed Induction Generator (DFIG) due to its lower cost, less power loss, variable speed, and four-quadrant operation. However, DFIG based WECS are highly sensitive to electric network disturbances because the stator of the DFIG is directly connected to the power system. Therefore, in this research study, the main attention is drawn towards the control of power electronic interface i.e., grid side converter of DFIG based WECS. The simulation results of symmetrical and asymmetrical faults, with different fault injection locations, are analyzed in order to provide a comprehensive understanding of the impact of electric grid disturbances on WECS. The results of the TS-type fuzzy controller are compared with the PI controller to illustrate the effectiveness of the fuzzy controlled DFIG based WECS. The aforementioned comparison of simulation results demonstrated that the transient stability of WECS is considerably improved by using TS type fuzzy controller. Thus, it is concluded that the TS-type fuzzy controller can be an efficient and promising solution for modern DFIG based WECS.

Throughout the developmental process of the wind energy conversion system (WECS), wind tunnel test is essential for the design and performance evaluation of the WECS. However, such a field test inevitably increases design time and cost due to the complex test settlement. Therefore, a wind turbine emulator that can closely imitate the turbine characteristics would merit the cost reduction of the WECS design. This paper reports on the development of wind turbine emulator and on how the emulator is utilized to evaluate the performance of WECS throughout the design flow. Testing results shown in this paper not only verify the emulator in reflecting the dynamic characteristics of the tested wind turbine, but also validate its usefulness in evaluating the performance of the WECS.

Preface. Chapter 1: INTRODUCTION. 1.1 A Brief History of Electric Power Systems. 1.2 The Structure of the Power System. 1.3 Outline of the Text. Chapter 2: BASICS OF ELECTRIC ENERGY SYSTEM THEORY. 2.1 Introduction. 2.2 Concepts of Power in Alternating Current Systems. 2.3 Three-Phase Systems. 2.4 The Per Unit System. 2.5 Electromagnetism and Electromechanical Energy Conversion. 2.6 Permeability and Magnetic Field Intensity. 2.7 Flux Linkages, Induced Voltages, Inductance, and Energy. 2.8 Hysteresis Loop. 2.9 Eddy Current and Core Losses. 2.10 Energy Flow Approach. 2.11 Multiply Excited Systems. 2.12 Doubly Excited Systems. 2.13 Salient-Pole Machines. 2.14 Round or Smooth Air-Gap Machines. 2.15 Machine-Type Classification. 2.16 P-Pole Machines. 2.17 Power System Representation. Problems. Chapter 3: POWER GENERATION AND THE SYNCHRONOUS MACHINE. 3.1 Introduction. 3.2 The Synchronous Machine: Preliminaries. 3.3 Synchronous Machine Fields. 3.4 A Simple Equivalent Circuit. 3.5 Principal Steady-State Characteristics. 3.6 Power-Angle Characteristics and the Infinite Bus Concept. 3.7 Accounting for Saliency. 3.8 Salient-Pole Machine Power Angle Characteristics. Problems. Chapter 4: THE TRANSFORMER. 4.1 Introduction. 4.2 General Theory of Transformer Operation. 4.3 Transformer Connections. Problems. Chapter 5: ELECTRIC POWER TRANSMISSION. 5.1 Introduction. 5.2 Electric Transmission Line Parameters. 5.3 Line Inductance. 5.4 Line Capacitance. 5.5 Two-Port Networks. 5.6 Transmission Line Models. Problems. Chapter 6: INDUCTION AND FRACTIONAL HORSEPOWER MOTORS. 6.1 Introduction. 6.2 Three-Phase Induction Motors. 6.3 Torque Relations. 6.4 Classification of Induction Motors. 6.5 Rotating Magnetic Fields in Single-Phase Induction Motors. 6.6 Equivalent Circuits for Single-Phase Induction Motors. 6.7 Power and Torque Relations. 6.8 Starting Single-Phase Induction Motors. 6.9 Single-Phase Induction Motor Types. Problems. Chapter 7: FAULTS AND PROTECTION OF ELECTRIC ENERGY SYSTEMS. 7.1 Introduction. 7.2 Transients during a Balanced Fault. 7.3 The Method of Symmetrical Components. 7.4 Sequence Networks. 7.5 Line-to-Ground Fault. 7.6 Double Line-to-Ground Fault. 7.7 Line-to-Line Fault. 7.8 The Balanced Three-Phase Fault. 7.9 System Protection, An Introduction. 7.10 Protective Relays. 7.11 Transformer Protection. 7.12 Transmission Line Protection. 7.13 Impedance-Based Protection Principles. 7.14 Computer Relaying. Problems. Chapter 8: THE ENERGY CONTROL CENTER. 8.1 Introduction 8.2 Overview of EMS Functions. 8.3 Power Flow Control 8.4 Power Flow 8.5 Stability Considerations 8.6 Power System State Estimation 8.7 Power System Security 8.8 Contingency Analysis 8.9 Optimal Preventive and Corrective Actions 8.10 Dynamic Security Analysis Chapter 9: THE PRESENT AND FUTURE OF ELECTRIC ENERGY SYSTEMS. 9.1 Introduction. 9.2 Challenges Facing the System. 9.3 Blackouts and their Impact. 9.4 Mitigating and Coping. REFERENCES. INDEX.

The focus of this study is on modeling and management of a Wind Energy Conversion System (WECS) based on a Hybrid Excitation Synchronous Generator (HESG). Using a wind simulator, two controllers, CRONE and H∞, are evaluated for Maximum Power Point Tracking (MPPT) and optimal rotation speed. The results show the CRONE controller's higher tracking capability, and robustness tests investigate the influence of parametric uncertainty. Space harmonic effects, commutation effects, and turbine shaft flexibility are all addressed in the sophisticated models. The introduction of Fractional Order Proportional‐Integral (FOPI) control for MPPT is a game changer. Although fractional calculus‐based accuracy and robustness are uncommon in WECS, they show promise for emissions reduction and increased energy efficiency. This work validates a dependable control approach inside an isolated HESG‐based WECS's power‐maximizing range. Extensive investigation of the parameters impacting FOPI control efficiency yields useful insights for effective MPPT control. A variable‐speed wind turbine (WT) is linked to a HESG through a multiplier, with a controller controlling generator coil excitation voltages and a rectifier connecting the WECS to a load. A thorough 3 kW HESG electrical model that includes generator space harmonics and converter commutation effects is among the contributions. For HESG‐based WECS stability, frequency analysis finds important resonant and anti‐resonant frequencies. These issues are addressed by a FOPI control technique, which ensures system stability and performance. The necessity of exact frequency analysis in HESG‐based WECS is highlighted by a step‐by‐step controller parameter tuning approach.