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The stator transient DC flux component emerges in the Double Fed Induction Generator (DFIG) following grid voltage dip, which results in an important influence on the controllability of rotor converter. In this paper, the research focuses on the responding time of the dynamic reactive current injection referring to DFIG with the crowbar protection under Zero Voltage Ride-Through (ZVRT). Firstly, theoretical...
Under voltage dip conditions, the induced rotor over-currents of the doubly fed induction generators (DFIG) may greatly destroy the converter switches. In this paper, a nonlinear control based on integral backstepping control (IBC) strategy is presented to enhance the Low voltage ride-through (LVRT) of DFIG. The goal of the proposed control strategy applied to rotor side converter (RSC) and grid side...
This research presents a new design of modified electrical controller structure of DFIG-based Wind Power Plant for transient stability analysis. In order to perform the transient stability analysis, the system is perturbed by a six-cycles three-phase transmission line fault. This new design consisted of AVR-PSS controller instead of using multistage PI controller in rotor field d-axis. The results...
This paper proposes a control strategy to improve the high voltage ride-through (HVRT) capability of doubly fed induction generator (DFIG)-based wind turbines in the event of a grid voltage symmetrical swell fault. The proposed solution is performed by an efficient control of a series grid side converter (SGSC), which suppresses the transient DC component of the stator flux. Thereby, the overvoltage...
This paper presents detailed analysis of the DFIG-based wind energy conversion system(WECS) under three-phase voltage dips conditions via a coupled simulation. 1.5MW DFIG is modeled in Ansoft-Maxwell, and the simulation is coupled with Ansoft-Simplorer and Matlab-Simulink for drive circuit and controller implementation. The coupled simulation system including DFIG, RSC, GSC, DC-Link, step up transformer,...
Doubly fed induction generator (DFIG) represents one of the more used generators for the conversion of wind energy, whose operation is based on the capacity to adapt their excitation to obtain grid-frequency voltage. An experimental study of a 4 kW DFIG is presented, together with the corresponding behavior modeling when interconnected to a grid of infinite power, under steady-state and transient...
Increasing wide spread use of wind power generation in power system continuously displaces synchronous generators. Variable speed wind turbines utilizing doubly fed induction generators (DFIG) are gaining prominence in power industry. Normally, DFIG does not offer any inertial response as its converter effectively decouples the inertia of DFIG from the system. Hence, the frequency control capability...
Asymmetrical voltage conditions in the grid can have significant negative effects on the performance of wind energy conversion systems (WECS) equipped with doubly-fed induction generators (DFIG). Transient peaks as well as steady-state second-order and higher frequency harmonics are introduced in the active and reactive output powers, in the DC-link voltage and in the toque produced by the WECS. These...
This paper presents an improved coordinated fault ride-through (FRT) control strategy for a doubly fed induction generator (DFIG) based wind turbine, (WT), in a weak grid. A technique for grid synchronization against voltage excursions, i.e., a Dual Second Order Generalized Integrator — Frequency Locked Loop (DSOGI-FLL) is utilized to extract a robust grid voltage synchronization signal irrespective...
When a non-bolted-three-phase-fault occurs in the outgoing transmission line from a DFIG-based wind farm with low-voltage-ride-through (LVRT) capability, the wind power side bus voltage and short-circuit current may have inconsistent main frequencies. This paper is devoted to exploring the reason theoretically. Based on the fundamental of induction generators, a simplified three-order dynamic model...
Wind farms WF connected to the power network are frequently subjected to grid faults, a large rotor current rising proportion happens during grid voltage sags. These faults may cause damages to rotor windings, converters, DC Link capacitor or induce drive train mechanical stress due to torque fluctuations. This paper develops a crowbar and chopper protection strategy to care for doubly fed induction...
Based on the basic voltage and flux equations of the Doubly Fed Induction Generator, this paper derived expressions of short-circuit current of wind turbines, which are expressed by transient equations of stator and rotor flux. The transient equations of stator and rotor flux were functions of initial values of stator and rotor flux and transient time constants of stator and rotor windings. The initial...
In this paper, different Model Reference Adaptive System (MRAS) based speed estimation methods are presented for a stand-alone Doubly Fed Induction Generator (DFIG) operating in the Variable Speed Constant Frequency (VSCF) mode. Among different MRAS based speed estimation techniques, stator flux based, rotor current based and reactive power based methods are compared in terms of their speed tracking...
This paper focuses on developing a novel algorithm which dynamically optimizes the controllers of doubly fed induction generator (DFIG) driven by a wind turbine (WT) to increase DFIG transient performance in all wind speed conditions. Particle swarm optimization (PSO) is proposed to optimize parameters of PI controllers of DFIG's rotor side/grid side converters (RSC/GSC) at different wind speeds in...
The doubly-fed induction generator (DFIG) is normally controlled with stator-flux orientation. Stator-voltage orientation and other methods like Direct Power Control can also be adopted. It is a poorly damped system with a natural frequency near the grid frequency. This leads to natural oscillations on the flux and torque and, for stator-flux orientation, in some cases, to instability. When voltage...
The use of the Doubly-fed Induction Generator (DFIG) in large wind turbines is growing rapidly. In order to investigate the dynamic response of a variable speed wind energy conversion system with DFIG connected to the power system during grid disturbance, a model has been developed. This model includes aerodynamics, the mechanical drive train, the induction generator as well as the control parts....
This paper analyzes the impact on transient and frequency stability for a power system at very high wind penetration (40% wind). Wind penetration is based on the doubly-fed induction generator (DFIG), and a systematic approach has been adopted for wind power integration. A sensitivity analysis has been carried out for each wind integration scenario and for different wind generator loading conditions...
Optimal fault ride-through (FRT) conditions for a doubly-fed induction generator (DFIG) during a transient grid fault are analyzed with special emphasis on improving the active power generation profile. The transition states due to crowbar activation during transient faults are investigated to exploit the maximum power during the fault and post-fault period. It has been identified that operating slip,...
Currently, some of the variable speed wind turbine on market have some low-voltage through capacity (LVRT), but do not have dynamic reactive power support capacity under fault. DFIG can't provide dynamic voltage support, in addition, as a result of lower terminal voltage, active power can not be completely output, which has impact on safe and stable operation of power grid. Aimed at this problem,...
The doubly-fed induction generator (DFIG) now represents the dominant technology in wind turbine design. One consequence of this is limited damping and inertial response during transient grid disturbances. A dasiadecoupledpsila strategy is therefore proposed to operate the DFIG grid-side converter (GSC) as a static synchronous compensator (STATCOM) during a fault, supporting the local voltage, while...
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