Search

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]

There are many conditions for determining the voltage-maximum loading relationship in multi-bus power systems. One of these is the line contingency in power systems. In this study, Effects on voltage stability of the line contingency occurred different points in IEEE 14 buses power system. Line contingency is considered as disabled for a certain period of time of the breakers situated in line. The effects of line contingency at 19 points on the voltage-loading parameter were observed. Besides, In this study, the effects of bus voltage profile changes were investigated. As a result of this study, it has been seen that line contingency decrease the system loading parameter value and operating limits in different transmission lines. In particular, the line contingency between the state transmission line 2-3, which brought the loading parameter value and the operating limits to the critical value. [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]