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In this paper, a robust non-linear controller based on block control linearization combined with a second order sliding modes technique called super-twisting algorithm is proposed for controlling a wind power system. The control objectives consist on maximize the wind energy capture by the turbine and keep the stator power factor of a wound rotor induction generator in a set point value. The goal...
The paper deals with squirrel cage induction generator connected to the grid through a back-to-back converter, which is driven by vector control. The stator side converter controls the generator torque using an indirect vector control. The grid side converter controls the DC Bus voltage and the reactive power. The proposed control strategy is validated by simulation in Matlab/Simulinkr®.
A usual wind energy conversion system (WECS) suffers from significant amount of torque ripples even if the wind velocity remains constant. These torque ripples propagate mechanical stress in the turbine-generator drive train and may eventually lead to the failure of its various components. This research paper presents a unified control strategy which yields maximum power from WECS while minimizing...
This paper presents an enhanced direct power control (DPC) algorithm for doubly fed induction generators (DFIG) capable of reducing the common mode voltage (CMV). Nowadays the DFIG is often used in high power wind energy conversion systems (WECS). A common problem of converter fed induction machines are the bearing damages due to the bearing currents. The source of this problem is the common mode...
This paper presents a Space-Vector Modulated (SVM) Direct-Torque-Control (DTC) scheme for a direct-drive permanent magnet synchronous generator (PMSG) and a gird converter for wind energy without any position sensor. Direct control of the rotating velocity and amplitude of the stator flux vector allows very fast torque response of the PMSG according to the generator speed. Fixed switching frequency...
In this paper, the problem of tracking control for variable speed wind induction generator (IG) energy conversion system (WECS) is investigated using nonlinear predictive control. A rotor speed predictive control algorithm has been designed to control the angular speed of the machine in order to allow the WECS operate with maximum power extraction. The generator torque is estimated and injected into...
Doubly fed induction generator (DFIG) is the most dominant technology used in wind energy conversion systems. Field-oriented vector control of DFIGs requires the knowledge of the instantaneous rotor position, which is usually obtained via high-resolution position sensors. However, using mechanical sensors increases the system cost and reduces the overall system reliability. This paper proposes a robust...
This paper presents a control strategy for a rectifier with variable speed direct driven permanent magnet synchronous generator. In order to achieve maximum power point tracking (MPPT) for wind power generation systems, the rotating speed of wind turbines should be adjusted in the real time according to wind speeds. The fuzzy logic controller is used to track generator speed with varying wind speed...
The maximum power point tracking (MPPT) strategy has great impact on the efficiency of the Variable-Speed Wind Turbine Generator (WTG) when the wind speed is below the rated speed. Now the MPPT has two control methods that are power control method and rotor speed control method. All of them had not used the wind speed information because the wind speed measured is usually inaccurate. In this paper,...
This paper analyzes the implementation of the sensorless control strategy for a doubly-fed induction generator (DFIG) for wind energy. The proposed algorithm can directly obtain the information of rotor position and speed via simple arithmetic operation by measuring the stator voltage, the rotor and stator currents. A DFIG sensorless digital control system has been carried out based on TMS320F2808...
This paper presents an integrated control strategy for a DFIG-based wind energy conversion system (WECS) with power quality enhancement capabilities. The proposed control scheme performs independent active and reactive power control of the DFIG by means of a robust direct power control (DPC) approach acting through the rotor side converter (RSC). Likewise, active filtering functionality is achieved...
This paper focuses on normal operation control of permanent magnet synchronous wind power generator system. It presents the system model theory and the operation control strategy under all the detailed information, such as reference direction of variables. Then a simulation for the normal operation of PMSG system is carried out in PSCAD with the desired results obtained.
Demand for wind power has increased considerably due to technological advances and favorable government policies. As a result, large wind farms with multi-megawatt capacity are connected to sub-transmission and transmission systems. With high penetrations of wind energy, performance of the overall system is affected by the technical impacts introduced by wind turbine generators (WTG). Fault current...
Unbalanced stator conditions cause rotor current harmonics and torque pulsations in Doubly-Fed Induction Generators (DFIG) which are used widely in wind energy systems. From a hardware perspective, current control techniques to minimize the rotor current harmonics include rotor-side converter injected voltage compensation and grid-side converter compensation. From a software perspective, the current...
An improved control scheme for sensorless vector control of grid-connected doubly fed induction generators (DFIGs) is presented when the network voltage is unbalanced. The system is based on a rotor current model reference adaptive system (MRAS) in the stator stationary reference frame. The observed rotational speed and rotor position angle are employed for the reference frame transformations of rotor...
In this paper, the sensorless control of a permanent magnet synchronous generator (PMSG) for wind turbine applications is presented. This kind of generator has many advantages, such as: high efficiency, high power density and low maintenance requirements. To improve these characteristics in the whole wind generator system a sensorless scheme is proposed, thereby avoiding problems of electromagnetic...
The paper deals with the impact of wind power integration on power system small signal stability. The DFIG wind turbine consisting of a back-to-back PWM converter is introduced. Generator model is given first, ignoring the transient of stator. The converter control, shaft and pitch angle control diagrams are picked out for a detailed study subsequently. A case study is performed in part three, eigen-analysis...
Crowbar-based control is one of the main low voltage ride through (LVRT) control methods for doubly-fed induction generator (DFIG), but converter is still at risk of being damaged by over-current at rotor side after crowbar exits during fault recovering period. For the issue, a model for fault process analysis based on equivalent dynamic model of DFIG is established. The mechanism of phase angle jumping...
Back to back full-size PWM converter is widely used in direct drive wind power system (DDWPS). It is the most cost-effective converter topology verified in field application. The characteristics of back to back full-size converter of DDWPS based on permanent magnetic synchronous generator (PMSG) are researched on in detail through a precise simulation and an experiment. The control strategy is given...
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