Wind energy conversion system

This paper proposes a new unified active filter so as to perfectly alleviate instantaneous unwanted oscillation of powers as they may lead frequency variations in weak systems due to the torque oscillations. First it presents negative impacts of capacitive loads on the shunt active power filter performance in compensation of the instantaneous oscillation of the real power. Second, an advanced universal power quality conditioning system (A-UPQS) is introduced for three-phase four-wire systems under non-ideal waveforms. Considering the suggested compensation algorithm, the advanced UPQS is able to extremely suppress instantaneous oscillating powers caused by the distortedunbalanced load-terminal voltages. Moreover, an independent single-phase converter is suggested at the load-end in order to regulate the DC-link voltage. Therefore, the instantaneous oscillating powers perfectly suppress and thus, source-end threephase currents would be purely sinusoidal. The suggested A-UPQS is used to stabilize micro grid frequency. The effectiveness and flexibility of the proposed Advanced UPQS is confirmed by Matlab/ Simulink simulations.

In this work, a statistical analysis of wind energy potential in Maiduguri is carried out, using Weibull distribution and 10 years (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) of wind data. The results show the Weibull distribution parameter C and K, the probability function T (V), the velocity frequency distribution f (V), the energy and power densities. The cost benefit analysis shows the economic feasibility of using wind energy conversion systems for electric power generation and supply in Maiduguri. r

The increasing influence of wind power in the power system operation has caused the power system operators to include wind power plants in the control of the overall power system, both in steady-state and transient operation. Therefore, the grid connection requirements of the power system operators involve wind power systems. Low voltage ride-through requirement is probably the most demanding grid connection requirement to meet, at least from the point of view of the wind energy conversion system. In presence of grid voltage dips, the low voltage ride-through compliance produces a mismatch between the generated active power and the active power delivered to the grid. The management of this mismatch supposes a challenge for the wind energy conversion system. In this work, a control scheme for the back-to-back neutral-pointclamped converter is proposed. Under grid voltage dip, the controllers for generator-side and grid-side converters work concurrently to meet the low voltage ride-through requirement by storing the active power surplus in the inertia of the generator and keeping constant the dc-link voltage. Simulation results verify the proposed control scheme.

Availability of wind energy and its characteristics at Kumta and Sirsi in Uttara Kannada District of Karnataka has been studied based on primary data collected at these sites for a period of 24 months. Wind regimes at Karwar (1952-89), Honnavar (1939 and Shirali (1974-89) have also been analysed based on data collected from India Meteorological Department (IMD) of respective meterological observatories. Wind energy conversion systems would be most effective in these taluks during the period May to August. The monthly frequency distributions of wind speed have been analysed for Kumta and Sirsi where hourly wind speed recording is available. It is shown that two parameter Weibull distribution is a good representation of the probability density function for the wind speed. Energy Pattern Factor (EPF) and Power Densities are computed for sites at Kumta and Sirsi. With the knowledge of EPF and mean wind speed, mean power density is computed for Karwar, Honnavar and Shirali. Our analyses show that the coastal taluks such as Karwar and Kumta have good wind potential. This potential, if exploited would help local industries and coconut and areca plantations. Premonsoon availability of wind energy would help in irrigating these orchards and makes the wind energy a desirable alternative.

Theoretical background included in part 1 of this work has shown the wide variety that the wind energy industry is offering in terms of electrical/electronic components and configurations. Though the first part of the course provides the student with an updated knowledge of the current technological status of the wind energy conversion systems (WECS), from the educational point of view the lectures are mainly teacher-centered and some relevant skills for electrical engineers are not excited. In spite of the breaking activities (videos, tests, challenging questions, etc), the role of the student keeps being somewhat passive. Aiming to overcome this shortcoming, this second part of the course places the student in the center of the teachinglearning process through hands-on work. The teacher becomes a consultant and the student has to build a wind energy system using simulation tools. Results of the experience prove that not only the motivation of the students is increased, but also the performance and acquisition of adequate competences.

This paper describes the dynamic behaviour of a doubly-fed induction machine, operating with wind turbine. The rotor circuit of the machine consists only of a generator-side converter working under abnormal condition at stator side (fault condition and voltage drop take place in transmission lines of the grid system). The induction machine model is based on the stationary reference frame and the control-unit model is based on the line-voltage oriented reference frame. The generator-side controller provides good decoupling between active and reactive power. A powerful MATLAB/SIMULINK was used for the simulation of the wind energy conversion system of a 4 kW wind generator. The simulation results of the generator side converter show that the speed, torque and the ϕ sin (power factor) can be regulated independently to match the reference signals. The effects of assumed abnormal condition in the grid system are discussed with regard to stator current and rotor current of the induction m...

This paper presents a novel power-balance control method for a wind-diesel generation feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an ac load using a power converter. An energy storage system (ESS), connected to the ac load using an additional converter, is used to balance the power generated by the WECS with the load. In this paper, the vector control systems for both interfacing power converters are discussed; the control uses the WECS converter to regulate the ac load voltage and the ESS converter to regulate the power flow to achieve a power balance. A small signal model is used to design the control systems. Finally, the proposed control is implemented in a 2-kW experimental prototype and the experimental results are fully analyzed and discussed in the paper.

This paper considers the problem of determining the locations of wind generators in a wind farm consisting of many generators. The objective is to find a generator placement that maximizes profit, which is the product of the cost efficiency of the generators and the total power output from the wind farm. Generator placement is significant because if generator A is located close to generator B and is located downwind of generator B then the power output of generator A is reduced by an amount that varies with the distance between the generators. The problem can be formulated using mathematical programming but to solve the problem one cannot employ traditional optimization methods. Therefore, a greedy improvement heuristic methodology is developed and described in detail. The effectiveness of the proposed heuristic is demonstrated on a suite of test problems. These results indicate that the proposed method represents an effective solution strategy for this problem.

Since the maturing of the wind farm industry, attention has been focused on the use of wind turbines for electricity production in remote areas. Generally, remote villages are driven by diesel generators. However, introduction/dissemination of wind energy conversion systems (WECS) into the existing diesel systems results in the reduction of the diesel fuel consumption and eventually allows atmospheric pollution to subside. A short-term energy storage integrated with wind-diesel system may compensate for fluctuations in the power output of the wind turbine and raise the fuel saving potential. The Kingdom of Saudi Arabia's (K.S.A) area is large, with large number of villages/settlements scattered all over the Kingdom. In the present study, hourly mean wind-speed data recorded at an airport, K.S.A., has been analyzed to investigate the technical and economic feasibility/viability of utilizing off-grid hybrid (wind-diesel-battery) power systems to meet the load requirements of a typical remote/isolated village with annual electrical energy demand of 13,244 MWh. The airport is located in the vicinity of the candidate settlement. The hybrid systems simulated comprise of various combinations (wind farms) of 600 kW commercial WECS supplemented with diesel generators and a short-term battery storage. The amount of battery storage capacity has been varied from 0 to 60 load minutes (equivalent to 0-60 min of average load). National Renewable Energy Laboratory's (NREL's) HOMER software has been used to perform the technical and economic analysis of hybrid wind-diesel-battery power systems. The investigation indicates that for a hybrid system consisting of 3.6 MW (six 600 kW wind machines, 50 m hub-height) wind farm capacity together with 4.5 MW diesel system (three 1.5 MW diesel units) and a battery storage of 30 load minutes (equivalent to 30 min of average load), the wind penetration is 24%. The cost of generating energy from the above hybrid configuration has been found to be 0.078 US$/kWh (assuming a diesel fuel price of 0.1 $/liter). The simulation results highlight that the number of operational hours of diesel generators in wind-diesel system decreases with increase in wind farm capacity. The study also illustrates that for a given hybrid wind-diesel system, the decrease in diesel run time is further enhanced by inclusion of battery storage capacity. An attempt has been made to address the effect of wind penetration, effect of hub-height on energy production, cost of wind-diesel-battery systems, cost of energy production, excess electricity, un-met load, percentage fuel savings and decrease in carbon emissions, etc (for different scenarios such as wind-diesel without storage, wind-diesel with storage, as compared to diesel-only situation).

This paper describes the design and implementation of hardware in the loop (HIL) system based on induction motor wind turbine emulator for the study of the operation of a combined heat-power (CHP) generating wind energy conversion system (WECS). The energy generation part of the WECS consists of two specially designed generators that are placed on a common vertical axis, which is connected to the induction motor through a gearbox. The first generator is an electric two-armature axial PMSG and the second one is a thermal electromagnetic retarder. The software part of the HIL setup simulates the interaction of the wind flow with a vertical axis wind turbine (VAWT) and is implemented in a programmable logic controller based on the model developed in the MATLAB/Simulink. The results of experimental studies of the CHP WECS with the created HIL simulative setup at both constant and turbulent wind speeds have shown good agreement with the corresponding results of computer simulation. The created HIL simulative setup will be used for the development of an energy management system for CHP WECS.

Permanent magnet synchronous generators (PMSG) applied to wind energy conversion system (WECS) using variable speed operation is being used more frequently in wind turbine application. Variable speed systems have several advantages over the traditional method of operating wind turbines, such as the reduction of mechanical stress and an increase in energy capture. To allow the variable speed operation of the PMSG WECS a conventional three-phase bridge rectifier (BR) with a bulky capacitor associated with a voltage source current controlled inverter (VS-CCI) is used. This simple scheme introduces a high intensity low frequency current harmonic content into the PMSG and consequently increases the total loses in it. Subsequently, decreases the power capability of the system. This paper presents a comparative simulation study between three different approaches applied to harmonic mitigation in PMSG WECS.

Egypt ABSTRACT This paper presents a brief review of the power electronics techniques in wind energy conversion systems. Utilization of power electronics converters enables to convert the generated power from any form to another and thus control the operation quality and obtain capture optimization. Attention is paid to converters selection and design to satisfy good matching between generator type and size, output form and purpose of control.

Hybrid energy systems are increasingly being applied in areas where grid extension is considered uneconomical. Their costs can be minimized through proper equipment sizing and load matching. This paper reports the results of optimization of hybrid energy system model for remote area in India. For this purpose, the Jaunpur block of Uttaranchal state of India has been selected as remote area. The model is developed with the objective of minimizing cost function based on demand and potential constraints. The model has been optimized using LINDO software 6.10 version. From the economic analysis, the capital cost, cost of energy for different types of resources, optimized cost of hybrid energy system are determined. In order to consider the fluctuation in the discharge and power generation from SHP, the EPDF has been varied from 1.0 to 0.0. The EPDF is electric power delivery factor and also called optimizing power factor and is maximum equal tol.

A wind speed sensorless neural network (NN) based maximum power point tracking (MPPT) control algorithm for variable speed wind energy conversion system (WECS) is proposed. The proposed method is developed using Jordan type recurrent NN which is trained online using back-propagation. The algorithm, without requiring the knowledge of wind speed, air density or turbine parameters, generates at its output the optimum speed command for the speed control loop of the vector controlled machine side converter control system using only the instantaneous power as its input. The output of the NN is fed into a state input after a unit step delay completing the Jordan type recurrent neural network. The proposed concept is analyzed in a grid connected direct drive variable speed permanent magnet synchronous generator (PMSG) WECS with a back-to-back frequency converter. Vector control of the grid side converter is realized in the grid voltage vector reference frame. Simulation is carried out in order to verify the performance of the proposed controller.

Doubly Fed Induction Generators (DFIGs) are nowadays extensively used in variable speed wind power plants. Doubly fed induction generators (DFIG) offer many advantages such as reduced converter rating, low cost and reduced losses with an improved efficiency, easy implementation of power factor correction schemes, variable speed operation and four quadrants active and reactive power control capabilities. Due to variable speed operation total energy output is much more in case of DFIG based WECS so capacity utilization factor is improved and cost of per unit energy is reduced. But the main disadvantage of DFIG is that it is very sensitive to grid disturbance/fault, especially for the voltage dip. Since the doubly-fed induction generator (DFIG) has been widely used in wind energy conversion, the low voltage ride through (LVRT) technology of the DFIG has been investigated extensively in recent times. This paper focuses on the Asymmetrical fault ride-through capability of doubly fed induction generator (DFIG) based WECSs. The paper also provides an overview on the interaction between variable-speed DFIG based WECSs and the power system subjected to disturbances. The dynamic behaviour of DFIG wind turbines during Asymmetrical grid faults is simulated and assessed.

This paper gives a review on the power electronic applications for wind energy conversion systems. Different types of wind energy conversion system (WECS) with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of WECS with different wind turbines are summarized and the possible uses of power electronic converters with wind farms are given. In conclusion, the possible methods of using the power electronic technology for improving wind turbine performance in power systems to meet the main grid connection requirements are discussed.

The depleting fossil fuel reserves and increasing concern towards global warming have created the need to surge for the alternative power generation options. Renewable energy sources like Wind, Solar-PV, Biomass and fuel cells are gaining prominence nowadays, as they are more energy efficient, reduce pollution and also they serve as a promising solution to the toughest energy crisis faced during the recent years. This paper focuses on the modeling and simulation of solar -photovoltaic, wind and fuel cell hybrid energy systems using MATLAB/Simulink software. The intermittent nature of solar and wind energy sources make them unreliable. Hence Maximum Power Point Tracking (MPPT) is used to extract maximum power from the wind and sun when it is available. The standard perturb and observe method of MPPT is used for the PV system and for the wind generation system. The simulation results of the PV/Wind /Fuel cell hybrid system are presented in graph showing the effectiveness of the proposed system model. Also, hardware implementation of microcontroller based MPPT for solar-PV alone and unit sizing of the hybrid system for the PG simulation lab in EEE Dept. of Thiagarajar College of Engineering is depicted in the paper.

One of the preferred technologies in variable speed wind turbines (VSWT) is formed by a wind rotor, permanent magnet synchronous generator (PMSG), three-phase bridge rectifier (BR) with a bulky capacitor, and power electronics converter for grid interface. High-intensity, low-frequency harmonic currents flows into the PMSG as electric load has a non-linear characteristic.

This paper analyses the electrodynamic braking (EDB) performance of a grid connected wind energy conversion system, during a grid loss. A dual pole induction generator driven by a fixed speed wind turbine is considered for the present study. The modeling of the wind turbine-induction generator unit, with the excitation capacitor C and braking resistor R, at the generator terminals is presented. Through simulation, the steady state as well as the dynamic performance of the system is studied for different R-C combinations. The experimental results on a 1.5 kW induction machine confirm the feasibility and effectiveness of the EDB. q

Φ Abstract --This paper deals with a wind energy conversion system (WECS), based on a doubly fed insduction generator (DFIG) and an electromechanical active power filter (APF). The objective is to respond simultaneously to electric energy requirement and power quality concerns. The proposed WECS is able not only to track the maximum power point of the wind energy but also to dampen harmonic currents from the grid line. To achieve these purposes, back-to-back pulse width modulation (PWM) voltage source converters (VSCs) are employed to excite the DFIG rotor. To control the power converters, two regulation loops, following the field oriented control (FOC) method, have been conceived. The first loop, dedicated to the rotor converter, enables a decoupled control of active and reactive powers flows. As well, it permits the cancellation of the most noteworthy harmonics from the utility current. The second loop, devoted to the front-end converter (FEC), makes it possible to regulate the DC-bus voltage shared between the two converters. Furthermore, the paper provides a study of the DFIG sub and super-synchronous operating modes which can be reached by acting on the wind speed. To demonstrate the performance of aforementioned WECS, a Matlab/Simulink model was established and simulated. Results seem to be very promising.

The energy demand around the world increases; the need for a renewable energy source that will not harm the environment has been increased i. e. Wind power is one of them. There are many loads (such as remote villages, islands, ships etc) that are away from the main grid. They require stand-alone generator system (which can provide constant nominal voltage and frequency) to provide for their local electrification. Wind power can be used in off-grid systems, also called stand-alone systems, not connected to an electric distribution system or grid.

This paper presents a new synchronization algorithm for grid connection of a doubly fed induction generator (DFIG) in wind generation system. A stator fluxoriented vector control is used for the variable speed DFIG operation. By controlling the generator excitation current the amplitude of the stator EMF is adjusted equal to the amplitude of the grid voltage. To set the generator frequency equal to the grid one, the turbine pitch angle controller accelerates the turbine/generator until it reaches the synchronous speed. A slight difference of stator and grid frequencies may cause the large phase difference between the two voltages. To compensate for this phase difference, a PLL algorithm is used. After the synchronization is achieved, the generator is connected to the grid and is controlled to extract the maximum power. The effectiveness of the proposed synchronization algorithm is verified by simulation results using PSCAD.

In the overall process of utilizing wind power, two essential components of technical data, i.e. one related to the engineering or performance characteristics of commercially available wind turbine generators, and the other related to the availability of wind resources, are needed. The performance of wind energy conversion systems (WECs) depends upon subsystems like wind turbine (aerodynamic), gears (mechanical), and generator (electrical). The availability of wind resources is governed by the climatic conditions of the region, for which the wind survey is extremely important to exploit wind energy. In this paper, design aspects, such as factors affecting wind power, siting requirements for WECs, problems related with grid connections, classification of wind electric generation schemes, criteria for selection of equipment for WECs, choice of generators, three basic design philosophies, main considerations in wind turbine design, choice between two and three blade rotors, weight and size considerations and environmental aspects related with WECs have been presented.

The axial flux (disc shape) permanent magnet machine is an attractive alternative to radial flux (cylindrical shape) machines in wind turbine applications. The axial flux configuration is amenable to the low-speed, high-torque operation of a direct drive wind energy system. Direct drive wind energy conversion tends to decrease the system size, weight, and noise, while increasing overall efficiency and reliability. When computing the magnetic field in axial field electric machines for machine design purposes, a 3-D electromagnetic finite element analysis (FEA) is generally required. However, FEA typically requires very long computation time, especially for 3-D computations. Furthermore, developing a proficiency in the use of electromagnetic FEA tools is not realistic for most undergraduate engineering technology students in a single semester. Therefore, an analytical model of the axial field machine that facilitates expeditious machine design and modeling is highly desirable. In this...

This paper presents a comparative study of sliding mode, artificial neural network and model reference adaptive speed observers for a speed sensorless permanent magnet synchronous generator (PMSG) in wind energy conversion system (WECS). Wind velocity and position sensorless operating methods for wind generation system using observer are proposed only by measuring phase voltages and currents. Maximum wind energy extraction is achieved by running the wind turbine generator in variable-speed mode. In addition the three speed observers are compared to verify the robustness against parameter variations.

In this paper, a new variable-speed wind energy conversion system (WECS) with permanent magnet synchronous generator (PMSG), Vienna rectifier and three-level neutral point clamped (NPC) inverter is proposed. Vienna rectifier is used for flux vector control of PMSG, maximum power point tracking (MPPT) of wind turbine, PMSG efficiency optimization, and balancing of two rectified DC voltages. As power conditioner, a three-level NPC inverter is used to deliver energy to the grid. Vector control of the inverter provides the ability to regulate power factor to any desired value. The results of two simulations (for back-to-back inverter and the proposed topology) are presented and compared. The results verify improved efficiency of the proposed WECS compared to WECS using back-to-back inverter. Copyright © 2010 John Wiley & Sons, Ltd.

The implementation of wind energy conversion systems in the built environment renewed the interest and the research on Vertical Axis Wind Turbines (VAWT), which in this application present several advantages over Horizontal Axis Wind Turbines (HAWT). The VAWT has an inherent unsteady aerodynamic behavior due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. The phenomenon of dynamic stall is then an intrinsic effect of the operation of a Vertical Axis Wind Turbine at low tip speed ratios, having a significant impact in both loads and power.

Wind Energy Conversion Systems (WECS) have become a focal point in the research of renewable energy sources. This paper provides then a comparative study of past and present generator technologies used in WECS. This study is based on an exhaustive review of the state of the art and on an effective comparison of the performances of the four main topologies that are permanent magnet generators, synchronous generators, induction generators and doubly-fed induction generators. The different generator-WECS schemes are compared on the basis of topology, cost, efficiency, power consumption and control complexity. Moreover, attempts are made to highlight future issues so as to index some emerging solutions.

This paper develops a framework of maximum power point tracking (MPPT) of doubly-fed induction generator (DFIG) based and permanent magnet synchronous generator (PMSG) based wind energy systems. The principles of MPPT in various wind generators are firstly investigated and feedback control schemes to realize MPPT with/without wind speed measurements are presented. Stability analysis of the wind energy conversion system with sensorless MPPT is investigated. Case studies of various wind energy system configurations are given to demonstrate the MPPT control schemes.

A technical and economic assessment has been made of the generation of electricity using wind turbines at one of the most promising wind sites in Egypt: Hurghada. In this paper, we used wind data recorded over 23 years for this site. The WASP program was used to calculate the values of wind speed frequency for the station, their seasonally values have been estimated and compared with measured data.

This paper presents the modelling and control design for a wind energy conversion scheme using synchronous generator. The wind turbine is coupled to a synchronous generator connected to grid trough a static converter. The objective of the proposed control strategy is to maximize energy captured from the wind turbine. The adapting control law used for extracting maximum power from the

A new system for studying power quality in wind energy conversion systems (WECS) has been designed using a data acquisition board (DAQ), LabVIEW programming software and a portable PC. The system has been installed at two wind turbines and at the power substation. Collected raw data are processed to get the main parameters of the system, power spectrums and dynamic response. The information obtained is completed with the data from a supply network analyser and from a data logger at the meteorological station

Doubly Fed Induction Generators (DFIGs) are nowadays extensively used in variable speed wind power plants. Doubly fed induction generators (DFIG) offer many advantages such as reduced converter rating, low cost and reduced losses with an improved efficiency, easy implementation of power factor correction schemes, variable speed operation and four quadrants active and reactive power control capabilities. Due to variable speed operation total energy output is much more in case of DFIG based WECS so capacity utilization factor is improved and cost of per unit energy is reduced. But the main disadvantage of DFIG is that it is very sensitive to grid disturbance/fault, especially for the voltage dip. Since the doubly-fed induction generator (DFIG) has been widely used in wind energy conversion, the low voltage ride through (LVRT) technology of the DFIG has been investigated extensively in recent times. This paper focuses on the Asymmetrical fault ride-through capability of doubly fed induction generator (DFIG) based WECSs. The paper also provides an overview on the interaction between variable-speed DFIG based WECSs and the power system subjected to disturbances. The dynamic behaviour of DFIG wind turbines during Asymmetrical grid faults is simulated and assessed.

This paper presents a more precise approach for static electromagnetic characterization of the variable speed switched reluctance generator (SRG) for application in the wind energy conversion system. The circuit-coupled two-dimensional finite element method (FEM) [2] for magnetic characterization of switched reluctance generator is presented. This approach yields more accurate results for a low speed switched reluctance generator with multiplicity of four. The magnetic characteristics such as flux linkage characteristics, inductance profile and torque profile have been obtained in a more accurate manner using this approach. I.

The use of a small wind turbine for the power supply of a radiative passive cooling system for indoor cooling or pre-cooling, even in areas with rather poor wind potential, was investigated in the present study. The passive cooling system was a lightweight aluminium nocturnal radiator, painted with an appropriate white paint and was established on the roof of the Department of Environmental and Natural Resources Management in Agrinio, in western Greece. The metallic radiator was used for indoor space cooling or pre-cooling, by providing cooled air to a specific thermal zone of the building of the Department. The limited energy demands of the system as well as the lighting demands of that specific thermal zone of the building were satisfied by a small wind turbine, placed on the roof of the building. Furthermore, the financial benefits of the system were investigated by a cost analysis, which gave excellent results and demonstrated that, even in areas with rather poor wind potential, there is the possibility of using wind power for domestic use in applications concerning indoor air conditioning. Finally, a neural network approach was used for modelling the energy consumption of a residential building in the area of western Greece using various wind energy and other climatic parameters.

The efficiency of the power generated from a Wind Energy Conversion System (WECS) can be maximized for a particular wind speed if the generator is driven at the optimal speed. For optimal operating point, a Maximum Power Point Tracking (MPPT) controller should be used. However, the variation of wind speed leads to difficulty in MPPT's control. In this paper, adaptive control techniques for determining the optimal operating point are presented and MPPT control, based on Adaptive Perturbation and Observation (APO) techniques, is proposed. The performances of the WECSs using the proposed adaptive control techniques are verified using numerical simulations. Furthermore, a comparison between these performances with those obtained using a Conventional Perturbation and Observation (CPO) controller is made, which results in that the proposed APO control techniques achieve better performance for MPPT control.

This paper describes a new wind turbine simulator for dynamic conditions. The authors have developed an experimental platform to simulate the static and dynamic characteristics of real wind energy conversion system. This system consists of a 3 kW dc motor, which drives a synchronous generator. The converter is a 3 kW single-phase half-controlled converter. MATLAB/Simulink real time control software interfaced to I/O board and a converter controlled dc motor are used instead of a real wind turbine. A MATLAB/Simulink model is developed that obtains wind profiles and, by applying real wind turbine characteristics in dynamics and rotational speed of dc motor, calculates the command shaft torque of a real wind turbine. Based on the comparison between calculated torques with command one, the shaft torque of dc motor is regulated accordingly by controlling armature current demand of a single-phase half-controlled ac-dc converter. Simulation and experimental results confirm the effectiveness of proposed wind turbine simulator in emulating and therefore evaluating various turbines under a wide variety of wind conditions. r

Control systems for variable-speed wind turbines (WTs) are continuously evolving toward innovative and more efficient solutions. Among the various techniques, fuzzy logic is gaining reputation due to its simplicity and effectiveness. In this chapter, after a review of fuzzy logic based control applied to wind energy conversion systems, a sensorless peak power tracking control for maximum wind energy extraction and a voltage control allowing compensation of voltage variations at the WT connection point are proposed. Both the controllers are based on fuzzy logic.

This paper presents a method for harmonic mitigation and maximum power point tracking (MPPT) for a variable speedgrid connected 20 kW wind turbine. The wind energy conversion systems consist of permanent magnet synchronous generator (PMSG) driven by variable-speed 20 kW wind turbine. The output of the PMSG is connected to a single switch three-phase boost rectifier to generate DC voltage which feeds a current controlled inverter to interface the system with the electric utility. The single switch three-phase boost rectifier is an active power factor correction technique to maintain the power factor at the PMSG side to nearly unity and mitigate the PMSG current harmonic. To mitigate inverter output current and voltage harmonics, an LCL filter has been used. A complete analysis of the harmonic content has been done everywhere in the system. The results show that the proposed MPPT control strategy succeeded to track the maximum wind power irrespective of the wind speed. This strategy in presence of LCL filter achieved harmonic mitigation at the PMSG and inverter output sides.

A fault detection and isolation (FDI) system for monitoring rotor current sensors in a doubly-fed induction generator (DFIG) for wind turbine applications is presented. The FDI system is designed so that the effect of parameter variations (resistances and inductances) is minimized. The residual generation is based on the generalized observer scheme (GOS) including parameter estimation. A decision system made of a combination of vector CUSUM (Cumulative sum) algorithms is used to process the residual vector and to achieve detection and isolation of incipient (small magnitude) faults. The approach is validated using signals obtained from a simulated vector-controlled DFIG.

The use of wind energy is now an established fact, and many educational institutions are introducing this topic into their engineering studies. Problem-based learning (PBL), as a student-centered instructional approach, has contributed to important developments in engineering education over the last few years. This paper presents the experience of a problem-based learning approach within the context of teaching wind energy conversion systems for electricity generation at an Electrical and Electronic Master's degree level. Students were given the problem of finding the response of a wind turbine to a grid fault. Groups of three students worked on a cooperative learning project for 15 weeks, with the instructor providing resource assistance and information at all stages of the work. Two tools were designed to help the students: a virtual wind turbine simulator and a real wind turbine setup. Both experimental tools are described, and the results obtained by the students are discussed. The results show that the students valued both tools and were able to address problems at a high cognitive level.

Wind energy conversion systems (WECS) have become a focal point in the research of renewable energy sources. In order to make wind turbine reliable and competitive, it is important to reduce the operational and maintenance costs. The most efficient way to reduce it relies on condition monitoring and fault diagnostics. This paper proposes a new fault detector based on the amplitude demodulation of the three-phase stator current. Simulations show that this low-complexity method is well suited for stationary or non-stationary behavior.

Wind energy conversion systems have become a focal point in the research of renewable energy sources. In order to make the DFIG-based wind turbines so competitive as the classical electric power stations it is important to reduce the operational and maintenance costs by continuously monitoring the condition of these systems. This paper provides a method for bearing fault detection in DFIG-based wind turbines. The proposed method uses the first Intrinsic Mode Function (IMF) of the stator current signal. After extracting the first IMF, amplitude-demodulation is performed to reveal a generator bearing fault. Experimental results show that the proposed method significantly improves the result of classical amplitudedemodulation techniques for failure detection.

Wind energy conversion systems have become a focal point in the research of renewable energy sources. In order to make wind turbines as competitive as the classical electric power stations, it is important to reduce the operational and maintenance costs. The most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the degradation of the generator health, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an approach based on the generator stator current data collection and attempts to highlight the use of Hilbert transformation for failure detection in a Doubly-Fed Induction Generator (DFIG) based wind turbine for stationary and nonstationary cases.

... when decreasing global reserves of fossil fuels threatens the long-term sustainability of global ... In Europe, offshore projects are now springing up off the coasts of Belgium, Denmark ... wind speed measurements the Materials and Energy Research Centre (MERC)-solar site, Tehran ...

The objective of this paper is to study the dynamic response of the wind energy conversion system (WECS) based on the Doubly Fed Induction Generator (DFIG). The DFIG rotor is connected to the grid via a converter. The active and reactive power control is realized by the DFIG rotor variables control, using the field oriented control (FOC). The vector control of DFIG is applied by the use of tow regulators PI and the neural network regulator (NN). The generator mathematical model is implemented in Matlab/ Simulink software to simulate a DFIG of 1.5 MW in order to show the efficiency of the performances and robustness of the studied control systems. The simulation obtained results shows that the robustness and response time of the neural network regulator is better than those obtained by the PI classical regulator.