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The use of the Doubly-fed Induction Generator (DFIG) in large wind turbines is growing rapidly, the wind farms are today required to participate actively in grid operation by an appropriate generation control. The study focuses on the direct power control (DPC) of the DFIG active and reactive powers (DPC) using the so-called sliding mode control (SMC). A model has been developed, including the mechanical,...
With the development of modern wind energy generation, higher requirements to the grid in case of a failure were raised. In order to faciliate the recovery of power, while voltage dips in a certain range, protecting the rotor side converter and providing reactive power to the grid are both needed according to the requirements. This paper takes DFIG for example, in order to protect the rotor side converter,...
The rate at which large variable speed wind farms are being developed had increased rapidly as the demand for green energy has grown. With this increase in distributed energy penetration into power networks, the main focus must be on power quality (Voltage Quality and Supply Reliability). However, new grid codes require wind energy generating systems to ride through grid faults, and at the same time...
Wind energy conversion systems using the doubly-fed induction generator (DFIG) are the most commercialized topology worldwide, because this technology uses converters dimensioned for ±30% of the system rated power, thus reducing the equipment cost. The direct connection of the DFIG stator to the electrical system increases its sensitivity to grid disturbances. In this context, this paper analyzes...
Doubly-fed induction generator (DFIG) is widely applied in Variable Speed Constant Frequency (VSCF) wind power system. In recent years the proportion of wind power became more and more in the electricity supply. The failure of power grid will lead to voltage drop and will cause system transient instability and may lead to partial or full paralysis. So Low Voltage Ride Through (LVRT) requirements is...
Recent wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage has been recovered. This paper proposes a new control strategy using DFIGs (Doubly Fed Induction Generators) for stabilizing a wind farm composed of DFIGs and IGs (Induction Generators). Simulation analysis by using PSCAD/EMTDC...
This paper presents a novel vector control strategy for the doubly-fed induction generator (DFIG) based wind turbine during grid voltage dips or swells. The transient electromagnetic process of the DFIG during the grid fault is discussed in detail. An improved control scheme with the dynamic process of stator excitation current variation taking into account is presented. Besides, the main magnetic...
Low voltage ride-through (LVRT) requirements, listed in modern grid codes, have proven to be a significant technical issue for many wind turbine manufacturers. The LVRT requirements are usually defined by the transmission system operators at the point of common coupling (PCC) of wind farm to the power network. However, depending on the transformers configuration, the voltage sag conditions experienced...
The increasing capacity of doubly-fed induction generator (DFIG) wind turbine across the globe demands quality power. Disturbance rejections & harmonics reduction are the two important issues to be considered to ensure quality of power. This paper presents the design of robust technique i.e. internal model control (IMC) to enhance the performance of DFI-based wind farm. The IMC is highly robust...
This paper presents the Direct model reference adaptive internal model controller for doubly fed induction generator used in wind farms based on MIT Rule adjustment mechanism with dither injection. Direct model reference adaptive internal model controller is developed and it is tuned using MIT rule. Rotor current controller is designed using direct model reference adaptive internal model controller...
The Brushless Doubly-Fed Induction Generator (BDFIG) shows commercial promise as replacement for doubly-fed slip-ring generators for wind power applications by offering reduced capital and operational costs due to its brushless operation. In order to facilitate its commercial deployment, the capabilities of the BDFIG system to comply with grid code requirements have to be assessed. This paper, for...
This paper proposes a VAR regulation strategy when voltage of monitor bus fluctuates or drops severely. If voltage of monitor bus fluctuates and the CrowBar does not response, rotor side converter will change VAR output of DFIG by regulation strategy while the converter of grid side can only keep DC voltage stability. When severe grid fault occurs and CrowBar acts, rotor side converter is out of control...
Doubly-fed induction generator (DFIG), as a wind generator, is economically justified, but control of the machine is difficult. In addition, it is significantly difficult to assure continuous operation of the DFIG during and after line-voltage distortions, as required by grid code. Nowadays, there is no single used method; the problem is not entirely solved. In the paper, not only features of the...
Due to the double fed induction generatorpsilas (DFIG) advantage of controlling active and reactive power independently and partial power converter, DFIG is becoming a popular type of wind power generation system. Nowadays, the grid code demands that the wind power generator possesses the ability of riding through the grid voltage sags, only when the grid voltage drops below the specific curve, the...
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...
For transmission system operators it is of great interest to estimate the behavior of their electrical system in case of large scale integration of wind generators. The main impacts are variations of the voltage and changes of the power flows. In this paper we detail how we have identified the main characteristics of a DFIG based wind generator and how we have detailed a corresponding model for power...
As the number and size of wind farms continue to grow, many countries have established or are developing a set of specific requirements (i.e., grid codes) for operation and grid connection of wind farms. The objective of these grid codes is to ensure that wind farms do not adversely affect the power system operation with respect to security of supply, reliability and power quality. This paper reviews...
Increasing penetration of the large wind farm in the system has forced the power system policy makers to develop new electricity grid codes which are required for the wind power generator to fulfill the same requirements as conventional power plants. In this paper, a series connected grid side converters with conventional doubly-fed induction generator (DFIG) scheme is explored to suit the grid code...
This paper proposes a new direct power control (DPC) strategy and a novel crowbar protection technique for the doubly fed induction generator (DFIG) used in the wind power generation systems. The main difficulty for a DFIG to ride through severe unbalanced grid voltage dips is the large transient currents induced in the rotor windings, which may damage the ac excitation converter. The proposed DPC...
In wind electrical energy generating systems, due to fast voltage and current fluctuations, the power converter represents a source of electromagnetic disturbances. EMI problems of stand alone wind generators are here analysed in order to take into account many different power quality problems which result in voltage fluctuations and harmonics in the net. This paper, moreover, presents a wind turbine...
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