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An analytical method of calculating an optimal resistance for crowbar of doubly fed induction generator (DFIG) under single phase fault is proposed by taking into account the impact of crowbar on reactive power, rotor current, voltage and electrical torque respectively. Finding the optimal resistance value for the crowbar is based on Analytic Hierarchy Process (AHP) in this paper, of the DFIG during...
This paper presents a new method for increasing the doubly fed induction generator (DFIG) performance under fault conditions. After the fault takes place, the rotor current increases to more than 8 times the nominal value, so the protective resistors called crowbar (Cb) will be switched on, and the current will be restricted. In order to stop injuring the rotor side convertor (RSC), the control signals...
In case of three-phase short circuit fault occurring at the terminal of a doubly-fed induction generator (DFIG), the rotor current characters of DFIG are analyzed from the viewpoint of the flux linkage, and the expression of the rotor current is deduced together with the estimated expression of the maximum rotor current. Based on above analysis, the max rotor currents and their appearing times with...
This paper studied mathematical model of doubly-fed induction generator (DFIG) based wind turbine generation system under unbalanced voltage. A dual-PI current control strategy was proposed to improve the performance of DFIG's rotor side convert (RSC) under asymmetrical voltage condition. The symmetrical component theory is employed to decompose asymmetrical three-phase variable such as voltage and...
Soaring oil prices, Climate change and global warming have attracted attention of various researchers to look for different renewable energy options for generating electricity. Wind energy has become one of most sought after options among the different renewable energy resources due to the advent of power electronic based controllers that allow constant frequency voltage to be generated irrespective...
The research of the steady-state characteristic of doubly fed induction generator (DFIG) can help us understand the working process of the generator.And in accordance with the features we can control the generator to improve the efficiency.On the basis of motor theory, the DFIG's mathematical model is established, and the relationship between the DFIG's stator active, reactive power and rotor's voltage...
The rotor of the doubly fed induction generator (DFIG) is fed back from the grid via back-to-back converters. Under the disturbance, the rotor current increases to maintain the terminal voltage and the rotor rotating speed of DFIG, while the current in the grid side converter also increases to keep the DC-Link voltage constant. In this situation, the overshoots of the currents flowing through the...
An improved control scheme for sensorless vector control of grid-connected doubly fed induction generators (DFIGs) is presented when the network voltage is unbalanced. The system is based on a rotor current model reference adaptive system (MRAS) in the stator stationary reference frame. The observed rotational speed and rotor position angle are employed for the reference frame transformations of rotor...
This paper presents an analysis of the reactive power capability (RPC) of doubly-fed induction generators (DFIG) system from the stability point of view. The stator flux orientated control (SFOC) is adopted in the DFIG system and the dynamics of rotor current is considered. The analytic stability of SFOC DFIG system has been deduced and verified on a 30 kW DFIG system using a back-to-back converter...
In this paper, a novel control method for smoothening the stator active or reactive power ripple components under unbalanced grid voltage for wind power generation using doubly-fed induction generators (DFIG) is proposed. The negative sequence component of the rotor current is used to reduce the active and reactive power ripples, which is extracted by band pass filters. It is shown that reducing the...
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