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Doubly fed induction generator (DFIG) is significantly affected by various faults occurring in the grid as they are directly connected to the grid. In order to realize the low voltage ride through (LVRT) capability, the DFIG must remain connected to the system for a certain period of time according to the grid code requirement. In order to achieve this, the high rotor current must be reduced in DFIG against faults occurring on the grid side. In this study, a decoupled feed-forward control model was developed for the LVRT capability. Positive, negative, natural, and forced methods were used for the decoupled feed-forward control (FFC) model. In addition to this developed model, while the stator electromotive force (EMF) model was developed for simulation study performance and ease of calculation, the rotor EMF model was also developed to predict the transient rotor current quickly. The developed models and the conventional model were used and compared in detail. According to the results obtained, it was observed that the system became stable owing to the developed model, while the oscillations formed as a result of the transient stability were damped. [ABSTRACT FROM AUTHOR]

One of the chief methods used to overcome voltage dip problems in doubly fed induction generator (DFIG)-based wind turbines is low voltage ride through (LVRT) capability. In order to solve such voltage dip problems during symmetrical and asymmetrical grid faults, this study presents a novel enhanced dynamic modeling approach for LVRT in DFIG. Positive and negative sequence models, along with natural and forcing flux models were used to enhance the proposed LVRT capability strategy for a DFIG. In addition, electro-motor-force (EMF) was applied for the enhancement of the stator and rotor circuit model. The novel statorrotor dynamic modeling was also used in boosting the transient stability operation against three phase and two phase faults. When the proposed dynamic modeling was applied, the system was stabilized within a short amount of time and the oscillations ceased. [ABSTRACT FROM AUTHOR]

The effects of nonlinear load models on the system are an important issue in terms of power quality. In this study, the effect of nonlinear load models in the grid-connected Doubly Fed Induction Generator (DFIG) based wind turbine was investigated. Exponential, constant impedance, constant current, constant active power (ZIP) and induction motor are used as nonlinear load model. Composite load modeling is consist of exponential-ZIP-induction motor. Composite load modeling is turn on and turns off system within different times. Analysis and stability analysis of the composite load modeling were examined. This simulation study was carried out in MATLAB / SIMULINK environment. 34.5 kV bus voltage, DFIG terminal voltage, DFIG electrical torque, DFIG d-q axis stator current variations and DFIG d-q axis rotor current variations in composite load model analysis are examined. As a result of, it has been seen that composite load modeling which is activated as short time is effective on the power system. [ABSTRACT FROM AUTHOR]

Low voltage ride through (LVRT) is one of the most popular methods to protect doubly fed induction generator (DFIG) against balanced and unbalanced voltage dips. In this study, a novel LVRT capability strategy is enhanced using forcing demagnetization controller (FDC) in DFIG-based wind farm. Moreover, not only stator circuit but also rotor circuit were developed by electromotor force (EMF) for LVRT in DFIG-based wind farm. The transient stability performances of the DFIG with and without the FDC and EMF were compared for three- and two-phase faults. In addition to variations such as 34.5 kV bus voltage and terminal voltage of DFIG, speed of DFIG, electrical torque of DFIG and d-q axis rotor-stator current variations of DFIG were also evaluated. It was seen that the system became stable within a short time using the FDC and EMF. [ABSTRACT FROM AUTHOR]

• Decoupled power-based sliding mode control modeling strategy was developed for uncertain parameters and chattering problems in DFIG. • The rotor electromotive force model was developed to provide dynamic stability in DFIG. • The stator electromotive force model was developed to improve the performance of the simulation study. • The developed models were examined via balanced and unbalanced fault analyses. Low-voltage ride through (LVRT) capability is the principal method used to counteract voltage dips and over-current, which are caused by various balanced and unbalanced faults. However, in providing LVRT capability during faults, oscillations that occur in parameter changes should be damped for a short time. In this study, a decoupled power-based sliding mode control (SMC) in doubly-fed induction generator (DFIG)-based wind turbines was developed in order to eliminate the oscillation problems that may occur during balanced and unbalanced faults. Besides, while the stator electromotive force model in DFIG is developed with the aim of improving simulation performance and enabling ease of calculation, the rotor electromotive force model is developed to dynamic stability in the system during various faults. The results obviously indicated that the proposed decoupled power-based SMC and stator-rotor electromotive force models enhanced the LVRT capability of the grid-code requirement and quickly restored dynamic stability to the system. [Display omitted] [ABSTRACT FROM AUTHOR]

Grid-connected doubly-fed induction generator (DFIG)-based wind turbines are very sensitive to voltage dip problems that occur in grid side. Therefore, different low-voltage ride-through (LVRT) capability methods are used to decrease the voltage dip problems. In this study, it is aimed to present a hybrid control approach to provide LVRT capability in DFIG. Moreover, it is aimed to develop electromotive-force (emf) models in a stator-rotor circuit. The rotor emf model is used to compensate for the voltage dip and reduce the oscillations while using the stator emf model to ensure the ease of calculation and accuracy of the simulation study. In the results, this paper is reporting that the hybrid control approach proposed in this study has given yield effective and better results in comparison with those of the conventional DFIG model. [ABSTRACT FROM AUTHOR]

• A new rotor resistance unit was developed for low voltage ride through capability in a doubly fed induction generator. • Stator and rotor dynamic modeling were developed against symmetrical and symmetrical faults. • Electromotive force models are developed in stator and rotor circuits. • A comparison was made of symmetrical and symmetrical faults with and without proposed model. It is very important to obtain smooth power and limit over-currents in grid-connected doubly fed induction generator (DFIG)-based wind turbines. Therefore, the rotor resistance unit can be used for power and over-currents control in DFIG. However, it may be insufficient to reduce oscillations in large power systems. This study aims to develop a new rotor resistance unit for low voltage ride through (LVRT) capability in DFIG. Moreover, electromotive-force (emf) models have been also developed in the stator and rotor circuit. The stator emf model of the simulation study was developed in the DFIG for accuracy and speed, while the rotor emf model was developed for over-current occurring in transient situations. In using the new rotor resistance unit and the stator-rotor emf, it was observed that the system stabilized in a short time, and the oscillations formed by the balanced and unbalanced faults on the grid side were damped. [ABSTRACT FROM AUTHOR]