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In the wind power application, different asymmetrical types of the grid fault can be categorized after the Y/d transformer, and the positive and negative components of a single-phase fault, phase-to-phase fault, and two-phase fault can be summarized. Due to the newly introduced negative and even the natural component of the Doubly-Fed Induction Generator (DFIG) stator flux during the fault period,...
In present doubly-fed induction generator (DFIG) wind turbines are widely remain connected to the grid network during faults, so-called Fault ride through (FRT). A crowbar is generally used in the rotor circuit protection which will help to support the FRT capability of the DFIG. In this paper, the behaviors of the DFIG system under three-phase faults influenced by the value of crowbar resistors are...
When there has a sudden drop of grid voltage, crowbar protection circuit is a widely used method to improve the low voltage ride-through ability of wind turbines with doubly fed induction generator (DFIG), which is commonly used in wind power. This paper studied three-phase symmetrical short circuit current characteristics of DFIG with crowbar protection in depth, and simulations have been made in...
This paper considers the use of a squirrel cage induction generator for a direct-drive wind turbine. Advantages of this topology include a simple/rugged construction, and no need for permanent magnets. A major focus of this paper is the choice of an appropriate pole number. An iterative, analytical design process is employed to create generators of different pole numbers for comparison, with static...
The DFIG is excited by converter which is connected rotor. The performance of wind turbine is depended on the matching conditions of the DFIG and converter. And the DFIG equivalent circuit parameter will influence the generator electromagnetic design. Based on the equivalent circuit and the test data, this paper put forward a kind of theory and calculation method to separate the equivalent circuit...
Doubly fed induction generators in conjunction with frequency converters allow the economic construction of large wind power plants with variable speed drives and a rated power output of up to several MW. Compared to fixed speed generators, the advantages of this configuration are high energy yields despite changing wind speeds, reduced negative effects on the grid and the possibility of reactive-power...
Nowadays, wind turbines implementing doubly fed induction generators (DFIG) occupy the largest share of the wind power market. These machines incorporate the benefits of variable speed generators in a cost-effective way but are very sensitive to grid disturbances and especially to voltage dips. To prevent the damages that grid disturbances can cause to the converter, the machines are equipped with...
In order to investigate the transient response of doubly fed induction generator (DFIG) under grid disturbances, an accurate model is required. This paper uses available DFIG models and investigates the influence of various model parameters and simplifications for both mechanical (two-mass model) and electrical (saturation) subsystems on DFIG based wind plant transient response. Then, the factors...
To study the effect of network disturbances on the dynamic performance of a vector controlled Doubly-Fed Induction Generator (DFIG), a grid connected DIFG with wind turbine has been implemented in PSCAD/EMTDC software environment and three different network disturbances are considered. A 3-phase short-circuit fault is made to study the behavior of the system during a severe voltage dip. By controlling...
This paper investigates the impact of the control system bandwidth on the detection of incipient faults in doubly fed induction generators used in wind turbines. In this application, the rotor is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The Impact of the closed loop control system cannot be neglected when the detection...
The doubly-fed induction generator (DFIG) based wind turbines of today are often equipped with a crowbar, which can be used to limit the inrush rotor current and protect the ac excitation converter from damage via a set of resistors that are connected to the rotor windings of the DFIG. When the rotor current becomes too high due to the severe grid voltage dips on the transmission line, the crowbar...
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