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To ensure safe and reliable operation of power system based on wind energy, usually plant operators should satisfy grid code requirements such as grid stability, fault ride through (FRT), power quality improvement, grid synchronization and power control etc. To satisfy the grid code requirements of wind turbine, usually grid side converter is playing a major role. So in order to improve the operation...
Brushless Doubly-Fed Machine (BDFM) is a machine which incorporates the robustness of the squirrel cage induction machine while having the speed and power factor control of a synchronous machine. A special kind of rotor called Nested-Loop rotor plays an important part in the BDFM, coupling the two stator fields. In future BDFM will share a large part in wind power market. This paper presents a mathematical...
Doubly Fed Induction Generators (DFIG) has emerged as a suitable alternative for conversion of wind energy to grid quality energy under varying wind conditions. Often the control mechanism use large number of sensors and employ complex computations. Moreover, the reported control schemes for DFIG employing grid side converter (GSC) do not ensure a drawl of unity power factor (upf) sinusoidal current...
This paper presents a quantitative analysis of the advantages of a grid connected doubly fed induction generator (DFIG) for wind energy conversion systems (WECS) over the other available variable speed WECS. The WEC system includes back-to-back connected PWM voltage source converters (VSC) in the rotor circuit of the DFIG. The control strategy implemented is - unity power factor operation of the machine...
This paper deals with the analysis, modeling, and control of a doubly-fed induction generator (DFIG) driven by the wind turbine. A control technique is presented for extracting the maximum power from the wind turbine. The wind energy conversion system (WECS) is equipped with a DFIG and two back-to-back connected voltage source converters (VSCs) in the rotor circuit. The proposed control technique...
Article studied asynchronous motor phased light load regulator of the principle of energy saving voltage regulator from the theory, impact of power efficiency of three key factors when the light load: Voltage, slip and power factor, proposed power-saving conditions. Running from the energy savings of view, in theory set up the ideas of the smallest energy consumption optimization target power factor...
A new energy-saving scheme of voltage-regulation control for induction motors at periodically varying loads with almost constant speed is presented in this paper. The energy-saving principle, control strategies, triggering mode of SCRs are studied. Based on the analysis of the current oscillation in the voltage-regulation by 3-phase thyristors with the synchronous voltage signal, the solution to current...
This paper presents the characteristic analysis on the high speed synchronous generator considering load conditions and power factor. The generator consists of the rotor with the short-circuited field coils connected to armature coils of an exciter and a stator with three-phase winding. To analyze the characteristics considering load conditions, the equivalent circuit method considering the effects...
A back-to-back PWM converter is used as the excitation power supply for the doubly-fed induction generator (DFIG) wind power generation of variable speed constant frequency (VSCF). The mathematical model and control strategy of converter which is connected between rotor and grid is analyzed. Grid-side converter adopts grid voltage oriented control scheme for achieving the stability of DC-link voltage,...
The stator-flux-oriented vector control strategy for double-fed induction motor was investigated in this paper. Three phase three-level rectifier was used as AC/DC block. This rectifier works with low harmonic distortion in the grid side. Besides, it maintains a high power factor while the energy flows in bidirectional way. For the DC/AC converter, three-level inverter was adopted. Using stator-flux...
This paper presents a direct torque control (DTC) applied to a three-phase asynchronous motor supplied by three-phase rectifier with absorption of the sinusoidal current cascaded with a two levels inverter in order to improve certain electrical sizes as the source current, and other mechanical characteristics as the undulations of the torque and the flux's distortion. The speed control is realised...
Full-scale experimental testing of the 7.5 kW doubly-fed induction machine controlled by matrix converter is reported. A number of doubly-fed induction machine and matrix converter control algorithms have been implemented in real time using a DSP-controller. The experimental rig used to control the doubly-fed induction machine is described. Experimental results demonstrate that the doubly-fed induction...
A method of sensorless vector control with unity power factor for surface mounted permanent magnet synchronous motor (SPMSM) is presented. The method can realize the motor control of unity power factor under the rated speed, and the motor can also work normally under high speed by way of field weakening. Comparing with the vector control of the statorpsilas magnetic force plumbs with the permanent...
Compared with the doubly-fed AC excited wind-power generation system, the directly-driven permanent magnet synchronous generator (PMSG) for wind-power system has advantage of simpler structure, higher generation efficiency and more reliable operation. To solve the weakness associated with the traditional id=0 control scheme, such as relatively large power rating for generator-side converter and correspondingly...
The paper deals with resultant stator-field vector control for a voltage-source inverter fed wound-excited salient- pole synchronous motor with damper bars. Two control strategies are presented: one for the constant, uncontrolled excitation and the other for controlled exciting current. The first method ensures the control of the stator-field oriented longitudinal armature reaction, which determines...
To optimize the operation of wind energy conversion systems (WECS), various types of power electronic converters had been employed between the generator and the grid. Stator voltage control has been used for improvement of power factor in grid-connected induction generators. However, this method reduces the efficiency drastically. Also the control range is limited. Two schemes are presented to improve...
The traditional dynamometers consume more fuel or electric energy while working, so they not only waste energy, but also have lower dynamic performance. An AC variable-frequency power dynamometer scheme is presented based on PWM rectifier and fuzzy direct torque control (DTC) of induction motor in this paper. The dynamometer can operate in both motoring and generating states. The bidirectional flow...
An improved direct torque control (DTC) scheme for the matrix converter fed interior permanent magnet synchronous machine (IPMSM) is presented in this paper. In the proposed scheme, the modified DTC strategy for matrix converter IPMSM drives is achieved using a variable-structure torque and stator flux controller, and indirect space vector modulation (ISVM) technique. It features low torque and flux...
A novel single-phase voltage source rectifier capable to achieve high-power-factor (HPF) for variable speed refrigeration system application, is proposed in this paper. The proposed system is composed by a single-phase high-power-factor boost rectifier, with two cells in interleave connection, operating in critical conduction mode, and employing a soft-switching technique, controlled by a field programmable...
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