Doubly Fed Induction Generator In Order Research Articles

Dynamic Stability Improvement of Synchronous Generator Using Suggested Controller in Reactive Power Band Of DFIG

Stability of synchronous generator and its improvement is one of the important problems in the power system. Stability can divided to three kinds: steady state, dynamic and transient which we study about dynamic stability in this paper. Nowadays pollution crisis in one hand and running out resources of fossil fuels on the other hand are caused increasing wind generations using based on doubly fed induction generator (DFIG). One of the abilities of DFIG is using it in order to improve dynamic stability in synchronous generator. In this paper, a suggested controller is used in the reactive power band of DFIG in order to increase dynamic stability of synchronous generator. This controller use two feedbacks of speed derivation in synchronous generator and DFIG electromagnetic torque. Finally, the simulation results for two disturbances in the test network show the suggested controller works correctly and the dynamic stability of synchronous generator has been increased remarkably.

Current Sensor Fault Detection and Isolation in Doubly Fed Induction Generator

Fault Detection and Isolation (FDI) is gaining interest as a means to increase the reliability and availability of efficient systems. Measuring sensors used for data acquisition are more prone to failures. The main objective of this paper is to provide model based FDI for current sensor fault closed-loop controlled Doubly Fed Induction Generator (DFIG) model connected to power grid. The sensor fault was detected and isolated by two methods including Unknown Input Observer (UIO) on reduced order DFIG model and fuzzy logic. The results show improvement in computational speed during online monitoring when the fault isolation is performed on reduced order models.

Maximum power extraction from fractional order doubly fed induction generator based wind turbines using homotopy singular perturbation method

In this paper, a novel control mechanism is presented for the control of variable speed wind turbine (VSWT) with a fractional-order doubly fed induction generator (DFIG) to extract the maximum power in region 2. Firstly, the homotopy singular perturbation method (HSPM) is proposed to simplify the fractional order nonlinear model, to reduce the long memory attribute, and to decrease the mechanical stress. This method is a composition of fractional order singular perturbation method (SPM) and modification of the homotopy perturbation method (HPM). Using this method, the nonlinear fractional order DFIG based VSWT is separated into two lower order subsystems, including nonlinear integer order subsystem and linear fractional order subsystem. Integer order modeling is applied to have the maximum wind power extraction and to increase the trajectory tracking speed, while the fractional order modeling is exerted to reduce the mechanical loads and to ensure better tracking. Then, a sliding mode controller based on HSPM is designed and applied to the original fractional order nonlinear system. Stability of the original system is evaluated by investigating the Lyapunov stability theorem for each subsystem. The controller performance designed based on HSPM is compared to the designed controller performance for fractional order nonlinear system decomposed using fractional order SPM, integer order nonlinear system decomposed by SPM, and integer order nonlinear system without simplification. The simulation results affirm the effectiveness of the controller design based on the proposed method.

Maximum power extraction from wind energy system using homotopy singular perturbation and fast terminal sliding mode method

In this paper, two strategies are proposed to simplify the dynamics and design of the controller for a variable speed wind turbine (VSWT) with a fractional order doubly fed induction generator (DFIG) in region 2. In the first strategy, the homotopy singular perturbation method (HSPM) is presented using fractional order singular perturbation method (SPM) and modified homotopy perturbation method (HPM). By exerting this method, the fractional order DFIG based VSWT is divided into two lower order subsystems, including nonlinear integer order subsystem and linear fractional order subsystem. In the second strategy, a nonlinear optimal second order fast terminal sliding mode controller (SOFTSMC) using the Lyapunov-based approach with negative definite solution is designed for nonlinear integer order subsystem. Also, a fractional optimal SOFTSMC is proposed by defining the subsystem error dynamics for linear fractional order subsystem. Finally, the control inputs designed for these subsystems are combined and applied to the original system. The main advantage of the HSPM is that both the integer and fractional modelings are used in the design process. The resulting fractional and nonlinear optimal SOFTSMC can be used effectively to achieve the maximum power extraction from the wind, reduce mechanical loads, attenuate the chattering, finite time convergence by applying a small control input, minimize the control input, ensure the better tracking, and tackle the effects of parametric uncertainties, unmodeled dynamics, and external disturbances. Stability of the original system is evaluated by investigating the Lyapunov stability theorem for each subsystem. The proposed controller designed by the HSPM is compared to some existing control laws, and their performance evaluation are reported in Table 1. The results of Table 1 guarantee the effectiveness of the proposed approaches.

Hybrid low voltage ride through enhancement for transient stability capability in wind farms

Abstract Protection of a doubly fed induction generator (DFIG) implemented for both wind farm and power systems is very important for transient stability. Crowbar circuits have been used for protection of DFIGs; however, a crowbar circuit is insufficient in terms of transient stability. Therefore, in this study, the passive Low voltage Ride Through (LVRT) capability method as well as the active LVRT capability method were developed for the purpose of transient analysis of the DFIG. The performances of DFIG models with and without active LVRT were compared. Modelling was carried out in a MATLAB/SIMULINK environment. Comparisons were made between behaviours of 3-phase fault and 2-phase fault systems and between rotor dynamic systems and those without a rotor dynamic. Parameters included DFIG output voltage, active power, speed, electrical torque variations and d–q axis stator current variations. In addition, a 34.5 kV bus voltage was examined. It was found that the system became stable in a short time when the active LVRT was incorporated into the reduced order DFIG model.

Integrated DFIG‐based wind turbine model with direct power control

This paper is focused on the model development of doubly fed induction generator (DFIG)‐based wind turbines. The model integrates mechanical and electrical systems. In the mechanical system, the aerodynamic properties are calculated in every section and every angle of attack by using a finite element analysis software, and the dynamic structure analysis is performed by using the Fatigue, Aerodynamics, Structures, and Turbulence (FAST) code. On the other hand, the electrical system includes DFIG modeling, the grid side converter (GSC) with DC bus voltage control, and the rotor side inverter (RSI) with direct power control (DPC). By using the direct power control strategy, the active power, reactive power, and power factor from the DFIG can be controlled to meet the requirements of the grid code. Moreover, the actual measured wind speed data are used in this work to simulate the outputs from the DFIG in order to confirm the feasibility of the wind turbine modeling. According to the simulation results, the proposed model is useful and can provide a reference for further studies about wind turbine technology. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Sub-Synchronous Resonance damping via Doubly Fed Induction Generator

Interests of low frequency oscillation damping with the Doubly Fed Induction Generator (DFIG) has been increased recently. In addition, it is widely accepted that, the Sub-Synchronous Resonance (SSR) is another unfavorable dynamical phenomenon in power systems. In this study, the implementation of the DFIG in SSR mitigation will be investigated. The IEEE second benchmark model aggregated with a DFIG based wind farm is employed as the case study. Two different control methodologies are proposed: a Fuzzy Logic Damping Controller (FLDC) and a conventional damping controller (CDC) that are added to the main control loop of the DFIG in order to damp the SSR. To validate the results of SSR suppression via DFIG, several case studies are introduced based on changing the operation point of the system and duration of the fault. It has been shown that the DFIG can damp the SSR through both proposed methodologies, but when the system operating point or fault duration is changed, the FLDC can present a cost-effective solution for SSR damping. The Fast Fourier Transform (FFT), simulation results, and a method based on performance index (PI) are conducted to compare two controllers through various cases in Matlab.