Double-fed Asynchronous Machine Research Articles

An Energy-Efficient Start-Up Strategy for Large Variable Speed Hydro Pump Turbine Equipped with Doubly Fed Asynchronous Machine

The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offers operational flexibility in many variable speed generation applications, such as in a hydroelectric pumped storage plant. In a variable speed hydroelectric pumped storage plant, the start-up process of DFAM is identical to the conventional singly fed asynchronous machine, wherein a significant amount of energy is wasted. This paper introduces an energy-efficient start-up strategy in DFAM based hydroelectric pump-turbine. The back-to-back voltage source converter connected to the rotor side is amenable for speed control (real power), braking (regenerative/dynamic), and starting the unit. Further, in this starting technique, the stator circuit of the machine is injected with a low voltage DC supply at starting instead of short-circuiting the windings. This DC injection reduces the slip losses and cuts down the magnetizing current requirement. The magnitude of the required DC supply is estimated based on the machine’s reactive power requirement. Also, the switching of stator winding between the short circuit connection, DC injection, and grid supply is carried out using a changeover switch and determined by the speed of the rotor. The proposed starting strategy is investigated with 250 MW DFAM in Matlab/Simulink environment and experimented with a 2.2 kW DFAM prototype. Test results show that the proposed starting method can conserve more than 26.1 percent of electrical energy in the example application compared to the conventional V/f start-up strategy.

Wind turbine doubly-fed asynchronous machine diagnosis defects using stator and rotor currents lissajous curves

<span>In </span><span>the current paper, a method is developed to diagnose potential electrical defects attacking doubly fed induction generator in Moroccan wind turbines firms. The proposed method is based on stator and rotor currents Lissajous curves analysis. Firstly, we focus on modeling of a non-defected wind conversion systems based on mathematic model created in Matlab Simulink which is able to reflect the behaviour of the wind turbine during asynchronous generator defects-free operation. After that, an indirect stator field vector oriented control is applied to obtain the wind system performance. Finally, stator and rotor currents Lissajous curves are analyzed in case of a non-defected generator that represents the system reference curves for diagnosing defects. The simulations had been realized by Matlab Simulink. Their results showed the effectiveness of the proposed method.</span>

Structural Model of the Electric Drive with Double-Fed Asynchronous Machine and Direct Torque Control

Abstract At present, the development of modern complex objects management systems, including electric motors, must include the step of modelling studies, which allows you to obtain basic characteristics, slightly different from the real characteristics of the object. The development of an adequate model, which can simulate the system under investigation, eliminates the stage of conceptual design and significantly reduce the engineering design stage, and therefore saves time and money.

Modeling and comparison of IP and fuzzy-pi regulators of speed control of DFIM for supply of power to the electrical network

This paper deals with a comparison between a fuzzy logic controller and a conventional IP controller utilized for speed control with a direct stator flux orientation control of a doubly fed induction. The effectiveness of the proposed control strategy is measured under diverse operating conditions such as of reference speed and for load torque step changes at nominal parameters and in the presence of parameter variation. Results obtained from simulation indicte that the fuzzy logic controller is more robust than a conventional IP controller against parameter variation and uncertainty, and is less sensitive to external load torque disturbance with a fast dynamic response; the stator side power factor is controlled at unity level. Then, an intelligent artificial fuzzy control of a wind energy system based on DFAM for supply of power to the electrical network. Its simulated performances are then compared to those of a classical PI controller. Specifically fuzzy systems are created to overcome the disadvantages of fuzzy systems. Results obtained in Matlab/Simulink environment show that the fuzzy control is more robust, have superior dynamic performance and hence found to be a suitable replacement of the conventional PI controller for the high performance drive applications. Key words : Doubly fed asynchronous machine (DFAM); Field oriented control; Fuzzy control, Fuzzy PI controller, conventional IP controller.

Wind Turbine Doubly-Fed Asynchronous Machine Diagnosis Defects—State of the Art

In this research paper, we will present the first works related to a state of the art and assess different defects found in two Moroccan wind turbine parks. In this respect, it is of paramount importance to shed light on these wind turbine parks and conduct a scientific research to analyze and come up with certain findings related to the issue under study. We are going to focus on the main defects that occur in wind turbines and thus we will sort out the most frequent ones in an attempt to provide an overall analysis of the system and its defects.

Modeling and fuzzy control of a wind energy system based on double-fed asynchronous machine for supply of power to the electrical network

The present paper proposes a model of fuzzy logic control of a doubly fed asynchronous machine (DFAM). First, a mathematical model of DFAM, written in an appropriate d-q reference frame, is established to investigate the results of simulations. In order to control the rotor currents of DFAM, a torque tracking control law is synthesized using PI controllers; the stator side power factor is controlled at a unity level. Then, artificial intelligent controls, such as fuzzy logic control, are applied. The simulated performances are then compared to those of a classical PI controller. Results obtained, in Matlab/Simulink environment, show that the fuzzy control is more robust i.e. has a superior dynamic performance and, hence, is found to be a suitable replacement of the conventional PI controller for a high performance drive applications.

Dynamics of an electric drive with a double-fed asynchronous machine under vector control

The dynamic behavior of an electric drive with a double-fed asynchronous machine under vector control is considered. The functional diagram of an electric-drive vector-control system, a mathematical model of the power part, the algorithms of the controllers, and the results of mathematical simulation of the electric drive are given. The simulation was carried out under the following conditions. The model of the induction motor takes into account the electromagnetic and electromechanical transient processes and the main magnetic-circuit saturation. The models of the frequency converters are assumed to be ideal elements. The mathematical description of the model of the power part is based on the presentation of variables (voltages, currents, and flux linkages) in the form of algebraic vectors components of which are given in a rotating rectangular coordinate system. The algorithms of the control-system controllers were synthesized using the method of nonlinear multivariable systems of subordinate control with the possibility of minimization of the total power losses of the saturated motor at a variable magnetic flux. The determination of the electric-drive dynamic responses is given based on the results of the simulation of transient processes in the evolution of the torque and speed during the starting and speed-up of the motor and upon the application of a mechanical load and upon unloading. During this simulation, the behavior of the electric and electromagnetic variables of the motor was controlled. The results of the mathematical simulation that were obtained under the above-formulated conditions allowed us to draw the conclusion that an electric drive with a double-fed asynchronous machine with vector control makes it possible to obtain transients close to those typical of the systems with a subordinate regulation in direct-current electric drives and optimize the total losses under the conditions of a variable magnetic flux.

Dynamic properties of the torque-control system in an electric drive with a double-fed asynchronous machine

Dynamic properties of an open-loop system of control of the electromagnetic moment that is part of an electric drive with a double-fed asynchronous machine have been considered. Analysis of a system of control of the electromagnetic moment with a subordinate system of control of currents of the stator and rotor windings of an asynchronous machine under the frequency control of the speed has been performed. Mathematical models of the elements comprising the system of the electromagnetic-moment control have been considered. These models describe the power part, the current controllers, and the regime former. In description of the elements of the electromagnetic-moment control system, the saturation of the main magnetic circuit of the machine has been taken into account. The program of the simulation of the processes is mainly aimed at the investigation of the effect of the speed of response of the current-control system on the dynamics of the open-loop system of the electromagnetic-moment control. Results of the simulation of the processes in the system of the electromagnetic-moment control at different speed of response of the current-control system are given. It has been shown that, with a decrease in the speed of response, the current controller begins losing the capability of compensating the effect of the disturbing action (the asynchronous machine speed is taken as this action). As a result, the orientation of the coordinate system, which is implemented by the moment controller, is disturbed and the dynamic characteristics of the systems of control of the electromagnetic moment and speed become worse. At a given speed of response of the current-control system, the characteristics of the efficiency of an open-loop system of control of the electromagnetic moment depend on the magnitude and speed of change in the controlling and disturbing actions. The dynamics of the system of the moment control is illustrated by graphs of transient processes in the case of a stepped setting of the controlling action and of the linear increase in the disturbing action. Based on the results of the investigations performed, the main conclusions and recommendations have been made.

Fuzzy control of a doubly fed asynchronous machine (DFAM) generator driven by a wind turbine modeling and simulation

The present paper proposes a model of fuzzy logic control of a doubly fed asynchronous machine (DFAM). First, a mathematical model of DFAM, written in an appropriate d–q reference frame, is established to investigate the results of simulations. In order to control the rotor currents of DFAM, a torque tracking control law is synthesized using PI controllers; the stator side power factor is controlled at a unity level. Then, artificial intelligent controls, such as fuzzy logic control, are applied. The simulated performances are then compared to those of a classical PI controller. Results obtained, in Matlab/Simulink environment, show that the fuzzy control is more robust i.e. has a superior dynamic performance and, hence, is found to be a suitable replacement of the conventional PI controller for a high performance drive applications.

The influence of supply voltage on the operating regime of a wind-power plant with a double-fed asynchronous machine

A procedure is presented of calculating the dependence on supply voltage of the operating parameters of wind-power plants hooked up to the power grid via double-fed asynchronous machines.

A Novel Control Method Of Variable Speed Pumped Storage Power Plant

Despite the advantages of variable Speed pumped storage power plant (PSP) included, as following statements: increasment of optimum efficiency in production mode and consumption mode, high speed for grid's requirements response in critical moments (such as: disturbances, black out,…); it's necessary, to achieve these benefits easily by energy storage practices. Now Doubly Fed Asynchronous Machine (DFAM) technology by means of modern equipment (MLVSC, Cycloconvertor) and employment of them is considered to achieve mentioned purposes, synchronous machines instead in PSP units. In this paper, technical comparison between the several kinds of PSP's drives methods is presented; also a PSP's unit is modeled (as electric, hydraulic, mechanic& control system) and simulated by Direct Torque Control (DTC) technique and TwoLevelVSC equipment, as novelty.Application of TwoLevelVSC and DTC method togethercaused to increase very high dynamic response of PSP in uninterrupted operationthe whole of times.The results of paper in Generation mode, express to increase efficiency in one unit of 4×250MW PSP that justifiesvariable SpeedPSP application. The simulations performed by Matlab software.

Modeling and Control of a Wind Power Conversion System Based on the Double-Fed Asynchronous Generator

Abstract 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 fuels, especially on sites less windy. The performance of a wind turbine depends on three parameters: the power of wind, the power curve of the turbine and the generator's ability to respond to wind fluctuations. This paper presents a control chain conversion based on a double-fed asynchronous machine (D.F.I.G) and flow-oriented. The supply system comprises two identical one converters connected to the rotor (RSC) and the other connected to the network (GSC) via a filter. The architecture of the device (Fig. 1) is up by three commands are necessary for the operation of the turbine control extraction of maximum power of the wind to control itself (MPPT) control of the RSC controlling the electromagnetic torque and stator reactive power and control of the GSC by controlling the DC bus voltage and active power and reactive power exchanged with the network. The proposed control, has been validated in both modes of operation of the three-bladed wind 7.5kw, using the Matlab / Simulink. The results of simulation control technology study provide good dynamic performance and static.

A Basic Study of Wind Generator Stabilization with Doubly-Fed Asynchronous Machine

This paper investigates the function of DASM (Doubly-fed ASynchronous Machine) with emphasis placed on its ability to the stabilization of the power system including wind generators. P (active power) and Q (reactive power) compensation from DASM can be regulated independently through secondary-excitation controlling. Simulation results by PSCAD show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures. Comparison studies have also been performed between wind turbine pitch control and proposed method.

Steady-state analysis of a doubly fed asynchronous machine supplied by a current-controlled cycloconvertor in the rotor

This paper deals with a doubly fed asynchronous machine (DFAM) supplied by a current-controlled cycloconvertor (CCC) at the rotor, and AC mains at the stator. A microprocessor is used to achieve control of the system by magnitude, frequency or phase shift of the output currents of the cycloconvertor. It also ensures the bank selection process. The mathematical model of the DFAM presented is based on a vectorial representation. Steady-state analysis of the CCC-fed DFAM has been carried out in the synchronous reference frame, and expressions of various output variables are developed. Performances of the drive are determined analytically. After theoretical analysis, the effect of the control parameters is investigated. Experimental results obtained show a good correlation with analytical predictions. Moreover, the range of variations of load angle must be limited to be within a certain value to verify stability conditions, and currents must not exceed the upper limits that the machine can carry.

Damping and Synchronizing Torque of the Double-Fed Asynchronous Machine

I. Introduction THE double-fed asynchronous machine has become important in recent times as fan drive with wide speed range. The system consists of five main machines and the fan (see figure 1). It has many springs, masses, and dampings and therefore many natural frequencies. In order to determine these frequencies, i.e. the dynamic stability of the system, the damping and synchronizing torques of all parts of the system have to be known. Some papers have been published concerning the torques of the synchronous machine. It is easy to determine torques for the D.C. machines of the system. The object of this paper is to derive formulas for the damping and synchronizing torque of the double-fed asynchronous machine. As in the case of the synchronous machine, a complicated derivation and complicated results cannot be avoided.

Damping and synchronizing torque of the double-fed asynchronous machine

I. Introduction THE double-fed asynchronous machine has become important in recent times as fan drive with wide speed range. The system consists of five main machines and the fan (see figure 1). It has many springs, masses, and dampings and therefore many natural frequencies. In order to determine these frequencies, i.e. the dynamic stability of the system, the damping and synchronizing torques of all parts of the system have to be known. Some papers have been published concerning the torques of the synchronous machine. It is easy to determine torques for the D.C. machines of the system. The object of this paper is to derive formulas for the damping and synchronizing torque of the double-fed asynchronous machine. As in the case of the synchronous machine, a complicated derivation and complicated results cannot be avoided.