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A new topology was recently developed to drive generators, aiming to avoid power electronic devices directly connected to the grid, and making possible the hybridization of the wind power with other sources. The system is composed by an induction machine with rotor in squirrel cage, and a rotating armature endowed with a three-phase winding that ma...
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... shaft attached to the gearbox, which supports the collector rings which receive the power from the inverter, is also mechanically connected to the EFR armature, although this coupling is not visible in the figure. Figure 3 presents the proposed generation system adapted from [13], replacing the synchronous generator by an induction one. Figure 3 presents the proposed generation system adapted from [13], replacing the synchronous generator by an induction one. ...
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This work is devoted to the study of a hybrid farm connected to the electrical grid. This farm is based on two renewable energy sources, wind turbines, and photovoltaic panels. The doubly-fed induction generator is used in this study because of its valuable advantages. Due to the different nature of these two energy sources, the hybrid coupling is...
Resumen:
Esta investigación propone una metodología de control aplicada a una técnica en Sistemas de Generación de Energía Eólica (WEGS) para el Seguimiento del Punto de Máxima Potencia (MPPT) basada en un observador Fuzzy y complementada con un controlador PI mediante el método de Control Directo de Velocidad (DSC). Este enfoque permite controlar...
This Research presents a novel approach to enhancing the performance and efficiency of a PV-wind-battery-based DC microgrid through the integration of a neural network maximum power point tracking (MPPT) system. The proposed system aims to optimize energy harvesting from photovoltaic (PV) panels and wind turbines while efficiently managing energy s...
Dans le cadre de la conversion à vitesse variable d’énergie éolienne (VS-WECS: Variable Speed, Wind Energy Conversion System), cet article propose une électronique de puissance simplifiée pour injecter l’énergie produite dans le réseau, spécialement dédié aux éoliennes de petite puissance (<100 kW). La chaîne de conversion comprend en série une gén...
The work presented in this paper deals with the active power control in a wind farm based on both central and local control levels. A central supervision unit (CSU) ensures the power coordination between the local supervision units (LSU) of each wind turbine. In the local supervision unit, a power management has been developed in order to adjust th...
Citations
... He has also shown that the EFR smoothes out mechanical oscillations caused by wind, which contributes to increasing the gear multiplier's service life. In another text Ramos et al. (2019) analyzed the application of the EFR in a large wind energy system, emphasizing the dynamic control of the maximum power extracted from the wind (MPPT). ...
This work analyzes the Electromagnetic Frequency Regulator (EFR) when used in a wind power system with hybridization of energy sources. The study was conducted through numerical simulation on Scilab platform. The conventional mechanical transmission (gearbox) was substituted by a hydrostatic system (pump and motor). Feedback linearization was used to control the motor’s displacement, and a prediction algorithm was developed to compute the reference steady-state angular speeds of the EFR’s armature and the rotating electromagnetic field. The results indicated that the EFR can effectively supply the generator load regardless of the wind speed. It was also shown that electrical energy can be accumulated in batteries during regimes of wind speeds higher than a reference set-point, to be used when the harnessed wind power is lower than the load. This shows that the EFR is a viable hybridization solution to wind energy systems, ensuring the highest levels of power quality.
... This asynchronous machine was the first type of generator to be used for high-power wind turbines [11,12,13,14,15], has definite advantages due to its simple design, low-cost manufacturing, robustness, low weight and inertia, and low maintenance (no brush collector) it requires [16,17,18,19]. ...
The need of electricity enhancement poses a challenge for researchers. This issue can only be achieved with the challenge of the quality, the safety and the stability of the electricity system. This paper discusses the influence of wind energy integration on the safety of the electricity Grid. The integration of two wind turbines separately is proposed. Indeed, the first asynchronous generator used is the Doubly Fed Induction Generator (DFIG) while the second is a Squirrel-Cage Induction Generator (SCIG). The proposed Grid is an IEEE 14 bus. We proposed to use a Breaker device to intervene abruptly on integration of the wind energy. A comparative efficiency performance has been carried out by treating the active and reactive power, showing the dynamic angle and the evolution of the voltage. The simulations of these turbines gave good results. The simulation results found by the DFIG are better than the SCIG.
... In addition, RES-based generation systems are usually connected to the grid through power converters, which can contribute to the increase of harmonic components in the voltages and currents generated. In order to overcome these problems, the use of an electromagnetic frequency regulator (EFR) to drive grid-connect electrical generators was proposed in the literature [11][12][13][14][15][16]. The EFR device consists of a modified induction machine, whose conventional armature mass can rotate, powered by a wind turbine or any other system that can impose a mechanical torque on its axis, as illustrated in Figure 1. ...
... In addition, the controllers' design can contribute to the system achieving the desired dynamic response in cases of abrupt speed and load variations, however, it was not discussed in this work. Subsequently, in [14], the EFR was employed in the driving of a squirrel-cage induction generator (SCIG) connected to the grid. In this work, the conjugate corresponding to the maximum wind power extraction was used to define the reference value of the EFR's rotor speed control loop. ...
... In [15], the proposal was to perform a power-quality analysis applied to the topology proposed in [14]. The analysis was based on the steady-state harmonic model of the EFRdriven generation system developed in the stationary frame. ...
The electromagnetic frequency regulator (EFR) device has proven to be an attractive solution for driving grid-connected electrical generators in distributed generation (DG) systems based on renewable energy sources (RES). However, the dynamic characteristic of the EFR has not yet been discussed for cases where its parameters vary from the nominal values. To evaluate this issue, this paper proposes a method for transient and steady-state performance analysis applied to the EFR device considering parametric variations. To perform this analysis, a dynamic model of the EFR device is derived, and its dynamic characteristics are discussed. Based on this model, the system’s controller gains are designed by using the root-locus method (RLM) to obtain the desired dynamic performance. Then, a sensitivity analysis of the closed-loop poles under the effect of parameters variation is performed. In addition, the paper also presents an analysis of the EFR-based system operating with the designed controllers. The proposed theoretical analysis is assessed using simulation and experimental results. The simulation program was developed using a Matlab/Simulink platform, while the experimental results were obtained through a laboratory setup emulating the EFR-based system.
... For the generator driven by the wind turbine (example), the mechanical characteristics are shown in Figure 4b. The wind turbine family of characteristics Ω pu E = f (−T pu E ) |V pu is given for various values V pu = 1; 0.8; 0.6; 0.4 of the wind velocity [1,7,11,[13][14][15][16][17]. The black points indicate the maximum power P E of the turbine for a given wind velocity. ...
... Water turbines have a lower variation in speed. The generator-type family of MIM mechanical characteristics of the wind velocity [1,7,11,[13][14][15][16][17]. The black points indicate the maximum power E P of the turbine for a given wind velocity. ...
... For the speed ranges between the characteristics for the remaining pairs of the supply sequence m = 2, 3 and m = 3, 4, the switching takes place on a similar principle. To properly set the ranges of operation, some methods can be applied, e.g., maximum power point tracking [7,13,14,16] or appropriate speed choice [5]. ...
The subject of this publication is a method of controlling the DC voltage of a PWM rectifier supplied by a multiphase cage induction generator with the number of stator phases greater than three operating in a wide range of driving speeds. Voltage regulation is performed by changing the frequency and amplitude of the stator voltages with simultaneous switching of the phase sequence of these voltages. The step change of the voltage sequence is made in the designated ranges of the generator speed, which enables the stabilization of the output voltage in a wide range from the minimum speed of about 25% of the rated speed. Such sequence switching changes the number of pole pairs produced by the winding for each supply sequence. The difference compared to multi-speed induction machines is that, in the presented solution, there is only one winding, not a few, which enables good use of the machine’s magnetic core in the same dimensions as for the three-phase machine of a similar power. Steady-state characteristics and dynamic operation were obtained using laboratory measurements of a standalone nine-phase induction generator. The automatic control system maintained the output voltage at the set level, regardless of the generator load and driving power.
... Despite that, the harmonic performance was not evaluated in the proposed topology. The regulation of a grid-connected SCIG driven by the EFR for maximum power point (MPPT) reference tracking is provided in [25]; however, the inverter was modeled as a sinusoidal voltage source as the purpose of the work was to validate the optimized control strategy. ...
... The major contribution of this paper is the detailed harmonic disturbance modeling and response analysis of the EFR, including the electrical and mechanical subsystems, as it was not covered in the related previous papers [23][24][25][26][27]. The mathematical model analyzes the harmonics components and the oscillations in active power and electromagnetic torque when the EFR armature voltage is distorted. ...
... The Electromagnetic Frequency Regulator (EFR) consists of an induction machine with a squirrel cage rotor and a rotating armature. A frequency inverter is used to adjust the electric current injected into the armature and deliver a desired angular speed to the Squirrel Cage Induction Generator (SCIG) rotor, despite the variable angular speed of the wind turbine (WT) [25]. The general steady-state equivalent model of induction machines in dq + is well accepted [14,22], and only the EFR harmonics modeling is presented in this paper. ...
The power quality analysis is an essential issue in the integration of distributed energy resources to the grid. Recent standards regulate the harmonics disturbances due to the increasing penetration of intermittent energy sources interconnected with the grid employing power converters. This paper aims to analyze the power quality of an interconnected wind turbine system based on a Squirrel Cage Induction Generator (SCIG) driven by an Electromagnetic Frequency Regulator (EFR). The steady state of the EFR harmonic model is developed in the stationary frame based on the conventional induction generator modeling, which allows the study of the harmonic disturbances in the electrical and mechanical variables due to the PWM inverter of the EFR’s armature voltage. There is no electrical connection between the EFR and SCIG, and the results show that the inherent system inertia contributes to the mitigation of the harmonic content at the grid side generated by the switching. In addition to the steady-state results, the Total Rated Distortion (TRD), which considers the harmonics and interharmonics components, was computed and presented a good performance compared to the IEEE 1547 standard and real data extracted of a single Doubly Fed Induction Generator (DFIG). Finally, the harmonic performance of the proposed system was evaluated considering the impact of the equivalent Thevenin impedance of the grid at the Point of Common Coupling (PCC).
... Although many wind turbine technologies are in use [1], and some others are in development [2,3], nowadays, the Doubly Fed Induction Generator (DFIG) is still used in about 50% of all Wind Energy Conversion Systems (WECSs) in operation. The predominance of this technology, in comparison to others, is due to its capacity of maximizing energy production in a wide range of wind conditions, allied to a good performance in dynamical response to input variations, including undesirable disturbance, in the Power System [1]. ...
The major objective of the investigation reported in this article is to demonstrate the feasibility of controlling a Doubly Fed Induction Generator actuating directly on the rotor voltage produced by the Rotor Side Converter, as its reference value may be determined analytically, after definition of the control objective. Two usual objectives are here considered: maximum power extraction from wind (MPPT) and stator reactive power equal to zero. This last objective defines the reference slip to be considered in the formulation of developed power that, jointly with the reactive power equation, forms the system to calculate the rotor reference voltages. The process is completed by specifying the desired dynamical response. Thus, the angular velocity of the rotor should quickly reach its reference value, which requires maximal power acceleration at the beginning, but respects the restriction that no overshoot should be allowed. This is achieved by means of a constrained optimization process solved in real time. Following recent trends, only measurements obtained from stator (voltages and currents) sensors are used. This way, angular velocity and rotor currents are estimated in real time. An algorithm for inductance estimation is also included, which prevents deviations of nominal values that could lead to false reference voltages.
... Although many wind turbine technologies are in use [1], and some others are in development [2,3], nowadays, the Doubly Fed Induction Generator (DFIG) is still used in about 50% of all Wind Energy Conversion Systems (WECSs) in operation. The predominance of this technology, in comparison to others, is due to its capacity of maximizing energy production in a wide range of wind conditions, allied to a good performance in dynamical response to input variations, including undesirable disturbance, in the Power System [1]. ...
The major objective of the investigation reported in this article is to demonstrate the feasibility of controlling a Doubly Fed Induction Generator actuating directly on the rotor voltage produced by the Rotor Side Converter, as its reference value may be determined analytically, after definition of the control objective. Two usual objectives are here considered: maximum power extraction from wind (MPPT) and stator reactive power equal to zero. This last objective defines the reference slip to be considered in the formulation of developed power that, jointly with the reactive power equation, forms the system to calculate the rotor reference voltages. The process is completed by specifying the desired dynamical response. Thus, the angular velocity of the rotor should quickly reach its reference value, which requires maximal power acceleration at the beginning, but respects the restriction that no overshoot should be allowed. This is achieved by means of a constrained optimization process solved in real time. Following recent trends, only measurements obtained from stator (voltages and currents) sensors are used. This way, angular velocity and rotor currents are estimated in real time. An algorithm for inductance estimation is also included, which prevents deviations of nominal values that could lead to false reference voltages.
Detailed analysis of wind energy conversion systems (WECS) has been thoroughly discussed in this chapter. Followed by wind turbine topologies, including designs with horizontal or vertical axis layouts architectural styles, and constant or variable speed designs. To maximize energy extraction from wind turbines and ensure efficient power conversion, the last section deals with converter control strategies and maximum power point tracking control.
This paper presents the implementation of a control strategy based on fuzzy logic artificial 1 intelligence (AI) for speed regulation of an electromagnetic frequency regulator (EFR) prototype, 2 aiming to eliminate the dependence on knowledge of physical parameters in the most diverse operat-3 ing conditions. Speed multiplication is one of the most important steps in power generation wind. 4 Gearboxes are generally used for this purpose. However, they have a reduced lifespan and a high 5 failure rate and are still noise sources. The search for new ways to match the speed (and torque) 6 between the turbine and the generator is an important research area to increase the energy, financial 7 and environmental efficiency of wind systems. The EFR device is an example of an alternative tech-8 nology that this team of researchers has proposed. It counts the fact of taking advantage of the main 9 advantages of an induction machine with the rotor in a squirrel cage positively. In the first studies, 10 the EFR control strategy consisted of the conventional PID controllers, which has several limitations 11 widely discussed in the literature. This strategy also limits the EFR's performance, considering its 12 entire operating range. The simulation program was developed using the Matlab/Simulink platform, 13 while the experimental results were obtained in the laboratory emulating the EFR-based system. 14 The EFR prototype used has 2 poles, a nominal power of 2.2 kW, and a nominal frequency of 60 Hz. 15 Experimental results were presented to validate the efficiency of the proposed control strategy. 16
This paper presents the implementation of a control strategy based on fuzzy logic artificial intelligence (AI) for speed regulation of an electromagnetic frequency regulator (EFR) prototype, aiming to eliminate the dependence on knowledge of physical parameters in the most diverse operating conditions. Speed multiplication is one of the most important steps in power generation wind. Gearboxes are generally used for this purpose. However, they have a reduced lifespan and a high failure rate and are still noise sources. The search for new ways to match the speed (and torque) between the turbine and the generator is an important research area to increase the energy, financial and environmental efficiency of wind systems. The EFR device is an example of an alternative technology that this team of researchers has proposed. It counts the fact of taking advantage of the main advantages of an induction machine with the rotor in a squirrel cage positively. In the first studies, the EFR control strategy consisted of the conventional PID controllers, which has several limitations widely discussed in the literature. This strategy also limits the EFR's performance, considering its entire operating range. The simulation program was developed using the Matlab/Simulink platform, while the experimental results were obtained in the laboratory emulating the EFR-based system. The EFR prototype used has 2 poles, a nominal power of 2.2 kW, and a nominal frequency of 60 Hz. Experimental results were presented to validate the efficiency of the proposed control strategy.
