DFIG

In this paper, we focus on the modeling and control of a wind power system based on a double-fed induction generator DFIG. We proposed a technique of active and reactive power control to improve the performance and dynamics of variable speed wind system. The objective of the modeling is to apply the direct and indirect vector control stator flux orientation to control independently, the active and reactive power generated doubly-fed induction generator (DFIG). The simulation results are tested and compared in order to evaluate the performance of the proposed system.

Abstract- This work presents a control strategy of a dynamic voltage restorer (DVR) to improve the doubly fed induction generator (DFIG) based wind turbine in case of fault. The application of a dynamic voltage restorer (DVR) connected to a doubly fed induction generator (DFIG) based wind-turbine-driven is investigated.Voltage in faulty line can be compensated using DVR, while nominal operation of DFIG wind turbine is continued as demanded in actual grid codes.

Nowadays, inverters are power electronics devices used in the renewable energy conversion systems. Therefore, the continuity of service of power converter has been a major concern. In this paper, a technique for diagnosing multiple open switch faults in three phase voltage inverters feeding Doubly Fed Induction Generator DFIG is presented. It is based on the so-called the Lissajous curves of DFIG rotor currents. For this purpose, the modeling of a non-defected wind conversion system based on mathematic model created in Matlab Simulink is firstly presented, after that, an indirect stator field vector-oriented control is applied to obtain the wind system performance. Finally, rotor currents Lissajous curves are analyzed in case of a non-defected and defected inverter. Simulation results show the effectiveness of the proposed method

In recent years, wind energy has become one of the most promising renewable energy sources. The doubly-fed induction generator (DFIG) is currently the most common type of generator used in wind farms. This paper describes an approach for the independent control of the active and reactive power of the variable-speed DFIG. This paper deals with the control of the active and reactive powers in a DFIG designed for a wind system. The simulation model including a 7 KW-DFIG driven by a wind turbine, a PWM inverter and the proposed control strategy are developed and implemented using Matlab Simulink.

Most of generators utilized in wind turbines are the Doubly-Fed Induction Generator (DFIG). Indirect matrix converter (IMC) is a candidate for substituting the traditional back-to-back converter in the future due to advantages gained by elimination of electrolytic capacitor. Starting DFIG wind turbines and synchronizing to the grid is a challenge in practice because of large inrush currents that could damage switches. Synchronizing the DFIG wind turbine controlled by the IMC is presented in this paper. Also, maximum power point tracking algorithm performance of this configuration is examined. A laboratory scale prototype of the proposed configuration is built. Experimental results have confirmed effectiveness of this configuration.

This paper deals with a DFIG model employing nine switches AC/AC converter. As compared to the conventional DFIG employing Back to Back power converter the nine switch converter requires fewer switches and gate drive circuits. Therefore proposed topology results in reduction of installation area and cost. The nine switch converter DFIG is applied to the wind turbine and integrated with the grid. The results reveal that even though change in wind speed occurred, the generator terminal voltage and frequency remain same. The generator output power follows the wind speed and delivers the more power to the grid.

Article history: Recently, the Gravitational-Search Algorithm (GSA) has been presented as a promising physics-inspired stochastic global optimization technique. It takes its derivation and features from laws of gravitation. This paper applies the GSA to design optimal controllers of a nonlinear system consisting of a doubly-fed induction generator (DFIG) driven by a wind turbine. Both the active and the reactive power are controlled and processed through a back-to-back converter. The active power control loop consists of two cascaded proportional integral (PI) controllers. Another PI controller is used to set the q-component of the rotor voltage by compensating the generated reactive power. The GSA is used to simultaneously tune the parameters of the three PI controllers. A time-weighted absolute error (ITAE) is used in the objective function to stabilize the system and increase its damping when subjected to different disturbances. Simulation results will demonstrate that the optimal GSA-based coordinated controllers can efficiently damp system oscillations under severe disturbances. Moreover, simulation results will show that the designed optimal controllers obtained using the GSA perform better than the optimal controllers obtained using two commonly used global optimization techniques, which are the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). 1. INTRODUCTION Generated electric power from wind is growing at an increasing annual rate worldwide in the last decade as its cost has decreased considerably. Widespread use of wind power can largely reduce production costs, reduce carbon emissions, contribute to resolving global warming calls, and reduce the dependency on fossil fuels [1]. With the recent developments in power electronics technology, DFIG driven by a wind turbine [2] are becoming very popular and their worldwide market share is increasing quickly. DFIG has been widely used in grid-connected variable-speed constant-frequency wind energy conversion systems (WECS) due to their advantageous features such as higher efficiency, lower cost, wide-range operations, capability of producing reactive power, better energy capture, smoother operation, and flexible control. Therefore, with the increasing utilization of wind power in the interconnected power network, improving DFIG transient performance is becoming more significant in power system operations. Tuning the parameters of a classical PI controller of a grid-connected DFIG-based WECS is complicated due to the high nonlinearity and complexity of the system. Optimization techniques are applied

The paper demonstrates the feasibility of an optimal backstepping controller for doubly fed induction generator based wind turbine (DFIG). The main purpose is the extract of maximum energy and the control of active and reactive power exchanged between the generator and electrical grid in presence of uncertainty. The maximum energy is obtained by applying an algorithm based on artificial bee colony approach. Particle swarm optimization is used to select optimal value of backstepping's parameters. The simulation is carried out on 2.4 MW DFIG based wind turbine system. The optimized performance of the proposed control technique under uncertainty parameters is established by simulation results. 1. INTRODUCTION The use of energy plays a vital role in making industrial and manufacturing process much more efficient. However, due to this large use, the production of unwanted materials that pollute air and contaminate soil and water was spawned an increase. In this way, the maximum rate of petroleum extraction has been reached and that subsequent methods of extraction cannot increase the rate further. One optimal solution to this problem is to use renewable energy sources. Their interest is that they do not emit greenhouse gases and produce no toxic and radioactive waste. Wind energy is one of the purest and eficient energy in the world for the production of electricity. The kinetic energy of wind is harnessed by wind turbines and converted into mechanical energy and finally into electrical energy. Quite recently, a large variety of publications have been undertaken for doubly fed induction generator modeling and control, in which vector control combined with proportional-integral (PI) loops is widely used in industry, due to its simple architecture, big advantages of decoupling active and reactive power, in addition high efficiency [1]. The main purpose of DFIG control system is to efficiently extract the wind power whatever the weather conditions, this is usually named maximum power point tracking MPPT [2-3]. A substantial review of this control is given on [4]. Meanwhile, an approach to attenuate the impact of failures in DFIG generator based wind is often required, so that DFIG can withstand some typical disturbances wind system. However, the major deficient of vector control is that it cannot keep a high level performance when parameter's system vary as its PI parameters are fixed, while system nonlineaty on DFIG is strong resulted from the fact that is a typical time-varying dynamic system with parametric uncertainties. Many efficient parameters tunning methods have been proposed to enhance the PI controller,

This article presents an improved direct vector command (DVC) based on intelligent space vector modulation (SVM) for a doubly fed induction generator (DFIG) integrated in a wind turbine system (WTS). The major disadvantages that is usually associated with DVC scheme is the power ripples and harmonic current. To overcome this disadvantages an advanced SVM technique based on fuzzy regulator (FSVM) is proposed. The proposed regulator is shown to be able to reduce the active and reactive powers ripples and to improve the performances of the DVC method. Simulation results are shown by using Matlab/Simulink.

In this research paper we investigate the modelling and control of a doubly fed induction generator (DFIG) driven in rotation by wind turbine, the control objectives is to optimize capture wind, extract the maximum of the power generated to the grid using MPPT algorithm (Maximum Power Point Tracking) and have a specified reactive power generated whatever wind speed variable, the indirect field oriented control IFOC with the PI correctors was used to achieve such as decoupled control. To validate the dynamique performance of our controller the whole system was simulated using dSPACE DS1104 Controller board Real Time Interface (RTI) which runs in Simulink/MATLAB software and ControlDesk 4.2 graphical interfaces.

In this paper, we present a robust control of a variable speed Doubly Fed Induction Generator (DFIG)-based Wind Energy Conversion System (WECS), using Fractional Order Control (FOC) to prevent system deterioration under different critical conditions (external disturbance, measurement noise and DFIG parameters variation). In order to extract the maximum power from the wind, a Maximum Power Point Tracking (MPPT) strategy based on rotor speed control is proposed. Furthermore, a vector control strategy is used for controlling active and reactive powers of DFIG. Additionally, a simple design method of Fractional Order Proportional Integral (FOPI) controller is proposed. Finally, the system's performance is tested and compared according to reference tracking, robustness, disturbance rejection and noise minimization.

Wind energy has many advantages, it does not pollute and it is an inexhaustible source. However, the cost of this energy is still too high to compete with traditional fossil sources. The yield of a wind turbine depends on three parameters: the power of the wind, the turbine power curve and the ability of the generator to respond to fluctuations in the wind. This article presented the MPPT of a wind turbine system equipped with an asynchronous generator has dual power under Matlab Simulink program, in the first time we simulated all the conversion chain with complete model of DFIG and vector control in second step then applied the extracted maximum power MPPT strategists, this command is effective and has several advantages it offered to kept the maximum power delivered to network despite all the parameter is change.

This study presents a control scheme of the electronic interface of a grid connected Variable Speed Wind Energy Generation System (VS-WEGS) based on a Doubly Fed Induction Generator (DFIG). The efficiency of the wind energy is represented to according to the control strategy applied. Thus, in the case of unbalanced grid voltage, the negative sequence voltage causes additional strong oscillation at twice the grid frequency in the stator instantaneous active and reactive powers. The objective of this work is to present an enhanced MPPT controller uses backstepping approach implemented in both dq + and dq − reference frames rotating to keep a safe operation of DFIG during unbalanced grid voltage associated with regulating rotor flux, in order to estimate rotor flux, a nonlinear observer based on sliding mode is proposed in this work. Note that the conventional controllers (PI, PI-R …) are not provided satisfactory performance during unbalanced voltage dips. The validation of results has been performed through simulation studies on a 4 kW DFIG using Matlab/Simulink

Concern over global climate change has led policy makers to accept the importance of reducing greenhouse gas emissions. This in turn has led to a large growth in clean renewable generation for electricity production. Much emphasis has been on wind generation as it is among the most advanced forms of renewable generation, however, its variable and relatively unpredictable nature result in increased challenges for electricity system operators. Tidal generation on the other hand is almost perfectly forecastable and as such may be a viable alternative to wind generation. This thesis paper shows the important of Tidal power over other sources and it’s generation using DFIG. This thesis is analyzed based on the following configuration; A 6 MW tidal power site having four, 1.5 MW tidal turbines connected to a 25 kV distribution system which ensures power to a 120 kV grid through a 30 km, 25 kV feeder line. A 2300V, 2 MVA plant with a motor load (1.68 MW induction motor at 0.93 pf) and of a 200 kW resistive load which is also linked into the same feeder. Both tidal turbine and motor is attached to a protection system which was used to monitor voltage, current and machine speed. DFIG DC link voltage is also monitored. Tidal turbines used an induction generator having a wound rotor and an AC/DC/AC IGBT based PWM converter. The stator winding is also linked directly to the 50 Hz grid and the rotor is fed at variable frequency through the AC/DC/AC converter. DFIG technology was also used for extraction of maximum energy from the tides for low tidal speeds through optimization of turbine speed, while lowering turbine mechanical stresses during heavy tides. The turbine’s optimum speed used to produce maximum mechanical energy for a given tidal speed which is directly proportional to tidal speed. The rotor runs at sub synchronous speed for tidal speeds will also be lowered at 10 m/s and at super synchronous speeds for higher tidal speeds. The simulation of 6MW tidal site was carried out for normal condition and at different types of faults introduced on the 25kV line. They are carried out as follows; a) For normal conditions, at a tidal speed of 13m/s. b) For a phase A to ground fault in the 25 kV line for t=5 to 5.1 seconds. c) For a phase A and B fault in the 25 kV line t=5 to 5.1 seconds. d) For a phase A and B to ground fault in the 25 kV line t=5 to 5.1 seconds. e) For a symmetric fault in the 25kV line for t=5 to 5.1 seconds

This paper proposes a feedback linearization control of doubly fed induction generator based wind energy systems for improving decoupled control of the active and reactive powers stator. In order to enhance dynamic performance of the controller studied, the adopted control is reinforced by a fuzzy logic controller. This approach is designed without any model of rotor flux estimation. The difficulty of measuring of rotor flux is overcome by using high gain observer. The stability of the nonlinear observer is proved by the Lyapunov theory. Numerical simulations using MATLAB-SIMULINK shown clearly the robustness of the proposed control, particularly to the disturbance rejection and parametric variations compared with the conventional method.

The proposal of this project addresses the reactive power generation of offshore wind parks using double fed induction generators (DFIG) connected to the main grid with long cables. During steady state operation, reactive power can be generated with minimum power loss of wind energy system while meeting the grid code requirement. During grid disturbance, the wind power generators have to provide voltage support by increasing reactive current supply. DFIG are the machines of choice for large wind turbines. The doubly fed induction generator system is investigated as viable alternative to adjust speed over a wide range while keeping cost of the power converters minimal. Decoupled control of active and reactive power can be realized using the dynamic model of the DFIG. The modeling and control of DFIG and the simulation was done in MATLAB Simulink environment and the results are verified.

This article proposes a novel scheme to improve the doubly-fed induction generator (DFIG) behavior during grid fault. The DFIG's are sensitives to voltage variations when abrupt variations of the wind velocity arrive. For enhancing DFIG behavior, protecting the converters, and smoothing the fluctuations power output of the DFIG under sag voltage; a novel hybrid energy storage system scheme and its controller are proposed. The main advantages of our approach are a faster response and suppressing overvoltage on DC bus and globally less stress in the storage system. The control structure decreases the tiredness on the battery and restores the DC bus voltage rapidly, globally the battery system operating time increases. The results obtained by simulations in MATLAB validate the benefits of the suggested control.

Abstract: This article presents an improved direct vector command (DVC) based on intelligent space vector modulation (SVM) for a doubly fed induction generator (DFIG) integrated in a wind turbine system (WTS). The major disadvantages that is usually associated with DVC scheme is the power ripples and harmonic current. To overcome this disadvantages an advanced SVM technique based on fuzzy regulator (FSVM) is proposed. The proposed regulator is shown to be able to reduce the active and reactive powers ripples and to improve the performances of the DVC method. Simulation results are shown by using Matlab/Simulink.

This work deals with the conversion of wind systems in order to improve the quality of the provided energy. To this end, we are interested in the modeling and the simulation of a Doubly-Fed Induction Generator (DFIG) with a wound rotor used in the electromechanical conversion of wind systems. In this paper, we carried out the modeling and the direct and indirect vector control of the (DFIG) by using a classical PI controller and then a fuzzy logic PI controller. The aim of these control systems is to minimize the interaction between active and reactive power and to ensure an efficient decoupling by the use of two algorithms: fuzzy logic control and classical control. The algorithms are developed and tested under Matlab/Simulink.

In  recent  years,  wind  energy  has  become  one  of  the  most  promising renewable  energy  sources.  Various  wind  turbine  concepts  with  different generator  topologies  have  been developed  to  convert  this  abundant  energy into  electric  power.  The  doubly-fed  induction  generator  (DFIG)  is  currently the  most  common  type  of  generator  used  in  wind  farms.  Usually  the  DFIG generator  is  a  wound  rotor  induction  machine,  where  the  stator  circuit  is directly connected to grid while the rotor’s winding is connected to the grid via  a  three-phase  converter.  This  paper  describes  an  approach  for  the independent  control  of  the  active  and  reactive  powers  of  the  variable-speed DFIG.  The  simulation  model  including  a  1.5  MW-DFIG  driven  by  a  wind turbine, a PWM back-to-back inverter and the proposed control strategy are developed  and  implemented  using  MATLAB/Simulink/SimPowerSystems environment.

This article presents an improved direct vector command (DVC) based on intelligent space vector modulation (SVM) for a doubly fed induction generator (DFIG) integrated in a wind turbine system (WTS). The major disadvantages that is usually associated with DVC scheme is the power ripples and harmonic current. To overcome this disadvantages an advanced SVM technique based on fuzzy regulator (FSVM) is proposed. The proposed regulator is shown to be able to reduce the active and reactive powers ripples and to improve the performances of the DVC method. Simulation results are shown by using Matlab/Simulink.

This paper describes a MPPT control of the stator powers of a DFIG operating within a wind energy system using the backstepping control technique. The objective of this work consists of providing a robust control to the rotor-side converter allowing the stator active power to be regulated at the maximum power extracted from the wind turbine, as well as maintaining the stator reactive power at zero to maintain the power factor at unity, under various conditions. We have used the Matlab/Simulink platform to model the wind system based on a 7.5 kW DFIG and to implement the MPPT control algorithm in a first step, then we have implemented the field-oriented control and the backstepping controller in a second step. The simulation results obtained were very satisfactory with a fast transient response and neglected power ripples. They furthermore confirmed the high robustness of the approach used in dealing with the variation of the internal parameters of the machine.

Wind energy has many advantages, it does not pollute and it is an inexhaustible source. However, the cost of this energy is still too high to compete with traditional fossil sources. The yield of a wind turbine depends on three parameters: the power of the wind, the turbine power curve and the ability of the generator to respond to fluctuations in the wind. This article presented the MPPT of a wind turbine system equipped with an asynchronous generator has dual power under Matlab Simulink program, in the first time we simulated all the conversion chain with complete model of DFIG and vector control in second step then applied the extracted maximum power MPPT strategists, this command is effective and has several advantages it offered to kept the maximum power delivered to network despite all the parameter is change.

In order to investigate a viable approach to fully exploit the wind speed, the present work investigates the application of a novel wind turbine consisting of dual doubly-fed induction generators (DFIG). The model can be further used to apply in areas where the winds are high to achieve high conversion efficiency in order to produce large electric power and increase the wind turbine capacity with an economy of hardware on the one hand, and to reduce the installation cost on the other. Furthermore, this model is always guarantees the continuity of power production because if one generator fails, the second generator will keep working until the broken one is repaired. The proposed model of the wind turbine based on dual doubly-fed induction generators (WT-dual-DFIG) were using the indirect field-oriented control (IFOC) was validated by wind turbine based on single doubly-fed induction generator (WT-single-DFIG) in MATLAB/Simulink. The results of simulation show that the simulated responses of the WT-dual-DFIG increased the power by a factor of about 14.3% compared to a WT-single-DFIG due to the use of a variable speed dual-DFIG. Finally, we can say that the WT-dual-DFIG model is strongly developed and could be applied in the coming years.

Nowadays, inverters are power electronics devices used in the renewable energy conversion systems. Therefore, the continuity of service of power converter has been a major concern. In this paper, a technique for diagnosing multiple open switch faults in three phase voltage inverters feeding Doubly Fed Induction Generator DFIG is presented. It is based on the so-called the Lissajous curves of DFIG rotor currents. For this purpose, the modeling of a non-defected wind conversion system based on mathematic model created in Matlab Simulink is firstly presented, after that, an indirect stator field vectororiented control is applied to obtain the wind system performance. Finally, rotor currents Lissajous curves are analyzed in case of a nondefected and defected inverter. Simulation results show the effectiveness of the proposed method.