Doubly Fed Induction Generator Wind Energy Conversion System Research Articles

Machine Learning Controller for DFIG Based Wind Conversion System

Renewable energy production plays a major role in satisfying electricity demand. Wind power conversion is one of the most popular renewable energy sources compared to other sources. Wind energy conversion has two major types of generators such as the Permanent Magnet Synchronous Generator (PMSG) and the Doubly Fed Induction Generator (DFIG). The maximum power tracking algorithm is a crucial controller, a wind energy conversion system for generating maximum power in different wind speed conditions. In this article, the DFIG wind energy conversion system was developed in Matrix Laboratory (MATLAB) and designed a machine learning (ML) algorithm for the rotor and grid side converter. The ML algorithm has been developed and trained in a MATLAB environment. There are two types of learning algorithms such as supervised and unsupervised learning. In this research supervised learning is used to power the neural networks and analysis is made for various hidden layers and activation functions. Simulation results are assessed to demonstrate the efficiency of the proposed system.

DC-Link Current Optimal Control of Current Source Converter in DFIG

In this paper, a novel control strategy of current source converter (CSC) is proposed for doubly-fed induction generator (DFIG) wind energy conversion system (WECS). Most of the studies on wind forms are based on voltage source converter, nevertheless, with the development of semiconductor technology and high switching frequency reverse block insulated gate bipolar transistor (RB-IGBT) devices being used in CSCs, the shortcomings of conventional CSCs including low switching frequency, large passive devices and slow dynamic performance can be overcome. Furthermore, WECS based on CSCs has various advantages, such like robustness, inherent short-circuit protection, fault ride through capability and so on. To implement the CSCs in DFIG wind energy conversion system, this paper analyzes the system configuration, operation principles, modulation strategy and control strategy. In addition, a novel control strategy based on DC-Link current optimal control is proposed. The simulation and prototype experiments verily the validity of system configuration and control strategy.

Sub-Synchronous Resonance Damping Control Strategy for DFIG Wind Turbines

Doubly-fed induction generator (DFIG) wind turbines connected to capacitive series-compensated transmission lines are prone to exhibit oscillatory behavior. The phenomena is called sub-synchronous resonances (SSRs), as these oscillations occur at frequencies below the fundamental component. This paper first develops a modeling methodology for DFIG wind turbines, based on impedance matrices, that is applied to model a real wind farm where SSRs were reported. The stability analysis performed shows how the interaction between the grid-side converter and the rotor-side converter contribute to the instability of DFIG wind energy conversion systems connected to series compensated grids. With this model, we propose a simple sub-synchronous resonance control strategy based on an orthogonal proportional action applied to the rotor currents, and a variable gain in the PI controller adjusted as a function of the DFIG rotational speed. This control strategy depends only on the rotor currents, which are local and already measured variables in any DFIG wind turbine, and is implemented in the rotor side converter, so it does not imply an additional cost at wind farm or wind turbine level and can be applied to any DFIG wind energy conversion system (WECS). Additionally, it proves to be robust for any line impedance series compensation level, and it does not need real-time information concerning the grid at which the wind turbine is connected, or its parameters. A real case study is considered, where the sub-synchronous resonance damping strategy presented in this work is able to stabilize the system for every possible line impedance compensation level.

Performance enhancement of a DFIG wind energy conversion system using phase advanced network

This paper presents the development of a phase advance network to enhance the performance of a variable-speed doubly-fed induction generator (DFIG) driven by a wind turbine under various operating conditions at Zafarana wind farm, Egypt. Firstly a fairly detailed simulation of a real DFIG-based wind energy conversion system is built using Matlab/SimPower environment. The simulation output is verified by comparing the simulation output with similar practical results and also with that published by Gamesa G5x standard test results. A phase advance network is designed and implemented to enhance the DFIG-based Gamesa G5x wind energy conversion unit. The FRT characteristics is examined when the system is subjected to a three phase short circuit test and the results obtained using the various enhancement techniques have presented in a comparative form with similar results using the implementation of the phase advance network. The results illustrate significant improvement in overall system performance and superior operation of the wind conversion unit using the phase network.

A novel controllable crowbar based on fault type protection technique for DFIG wind energy conversion system using adaptive neuro-fuzzy inference system

This paper proposes a novel controllable crowbar based on fault type (CBFT) protection technique for doubly fed induction generator (DFIG) wind energy conversion system connected to grid. The studied system consists of six DFIG wind turbines with a capacity of 1.5 MW for each of them. The operation mechanism of proposed technique is used to connect a set of crowbar resistors in different connection ways via activation of controllable circuit breakers (CBs) depending on the detected fault type. For each phase of DFIG, a crowbar resistor is connected in parallel with a controllable CB and all of them are connected in series to grid terminals. The adaptive neuro-fuzzy inference system (ANFIS) networks are designed to detect the fault occurrence, classify the fault type, activate the CBs for crowbar resistors associated with faulted phases during fault period, and deactivate them after fault clearance. The effectiveness of proposed CBFT protection technique is investigated for different fault types such as symmetrical and unsymmetrical faults taking into account the single-phase to ground fault is the most frequently fault type that occurs in power systems. Also, a comparison between the behaviours of studied system in cases of using traditional parallel rotor crowbar, classical outer crowbar, and proposed CBFT protection techniques is studied. The fluctuations of DC-link voltage, active power, and reactive power for studied system equipped with different protection techniques are investigated. Moreover, the impacts of different crowbar resistance values on the accuracy of proposed technique are studied. The simulation results show that, the proposed technique enhances the stability of studied wind turbine generators and contributes in protection of their components during faults.

Perturbation estimation based robust state feedback control for grid connected DFIG wind energy conversion system

This paper develops a perturbation estimation based robust state feedback control (PER-SFC) scheme of doubly-fed induction generator (DFIG) for maximum power point tracking (MPPT). The combinatorial effect of nonlinearities originally stemmed from wind turbine aerodynamics, generator modelling uncertainties and wind speed randomness is aggregated as a perturbation, which is rapidly estimated online by a sliding-mode state and perturbation observer (SMSPO). Then, a linear state feedback controller is designed to fully compensate the perturbation estimate in real-time. Furthermore, only the measurement of rotor speed and reactive power is needed while no accurate DFIG model is required by the proposed approach. Under such framework, the elegant merits of conventional linear state feedback control (favourable implementation simplicity and high reliability) and nonlinear robust control (global control consistency and considerable robustness) can be wisely incorporated. Meanwhile, their inherent drawbacks could be significantly reduced. Case studies are undertaken which verify the effectiveness and superiority of PER-SFC compared to that of other classical methods.

Quantitative and qualitative behavior analysis of a DFIG wind energy conversion system by a wind gust and converter faults

AbstractA wind gust can cause severe dynamic conditions that affect the operational behavior of the whole doubly fed induction generator (DFIG) wind energy conversion system and, as a result, the quality of power exchanged with the grid. In addition, it can cause great disturbances to critical system's variables with possible damages to the system's construction—to mechanical or electrical part. The knowledge of DFIG reaction in such conditions is useful for both protection issues and the risk assessment concerning system's tolerance, maintenance costs and revenue losses, because of the disconnection from the grid. In this paper, a quantitative and qualitative behavior analysis of a 2 MW DFIG wind energy conversion system under a wind gust and converter faults, which has been carried out via simulation, is presented. The pitch controller parameters impact to its behavior, when a gust appears, has been investigated. Copyright © 2015 John Wiley & Sons, Ltd.

Dynamic Model and Control of DFIG Wind Energy Systems Based on Power Transfer Matrix

This paper presents a power transfer matrix model and multivariable control method for a doubly-fed induction generator (DFIG) wind energy system. The power transfer matrix model uses instantaneous real/reactive power components as the system state variables. It is shown that using the power transfer matrix model improves the robustness of controllers as the power waveforms are independent of a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> frame of reference. The sequential loop closing technique is used to design the controllers based on the linearized model of the wind energy system. The designed controller includes six compensators for capturing the maximum wind power and supplying the required reactive power to the DFIG. A power/current limiting scheme is also presented to protect power converters during a fault. The validity and performance of the proposed modeling and control approaches are investigated using a study system consisting of a grid-connected DFIG wind energy conversion system. This investigation uses the time-domain simulation of the study system to: 1) validate the presented model and its assumptions, 2) show the tracking and disturbance rejection capabilities of the designed control system, and 3) test the robustness of the designed controller to the uncertainties of the model parameters.