Induction Generator Wind Turbine Research Articles

Stability check of doubly fed induction generator (DFIG) micro grid power system

As of late, expanding interest of renewable energy and consumption of non-renewable energy source have prompted developing advancement of renewable energy technology, for example, wind energy. Wind energy has turned out to be one of the reliable sources of renewable energy, which requests extra transmission capacity and better methods for sustaining system reliability. As of now, doubly fed induction generator wind turbine is the most well-known wind turbine. This paper focuses on DFIG wind farm design using MATLAB/SIMULINK and also investigates the issues of the system stability of the DFIG wind turbine micro grid power system. This analysis includes the changes of voltage, current, real power and reactive power based on various conditions of the power system.

A novel adaptive model predictive controller for load frequency control of power systems integrated with DFIG wind turbines

With the rapid growth of renewable energy resources, wind energy system is getting more interest everywhere throughout the world. However, its extensive use in power systems prompts many power system dynamics and stability problems. Load variation and anomalous operating conditions prompt inconsistencies in frequency and planned power trades. These inconsistencies should be remedied by load frequency control. This paper introduces a novel frequency control system utilizing a mix of adaptive model predictive controller (AMPC) and recursive polynomial model estimator (RPME) integrated with double fed induction generator wind turbines. Inside each control duration, the RPME is identifying a discrete-time online autoregressive exogenous model. The latter is used through the AMPC to update the interior plant model in order to achieve a successful nonlinear control. The performance of the proposed system has been verified and contrasted with the conventional MPC system through a computer simulation-based MATLAB/SIMULINK. The simulation results demonstrated the superiority of the proposed system as for the conventional MPC system.

A Novel Aggregation Method for Doubly Fed Wind Farm

With the increasing penetration of wind power, many problems like frequency and voltage stability appear frequently, so the power grid gradually requires that the wind farm can be dispatched and controlled. In this paper, a new aggregation method is proposed to calculate the aggregated active and reactive power regulation range of a doubly-fed wind farm, which provides a dispatching reference for the power system control center. In this method, voltage security and different operation states of wind turbines and internal power losses of the wind farm are considered. Finally, the actual aggregated P-Q regulation range of the wind farm that can ensure operation safety is obtained. A wind farm with 25 doubly fed induction generator (DFIG) wind turbines is used to verify the proposed aggregation method.

Stability Assessment on Doubly Fed Induction Generator (DFIG) Wind Turbine Micro Grid Power System

As of late, expanding interest of renewable energy and consumption of non-renewable energy source have prompted developing advancement of renewable energy technology, for example, wind energy. Wind energy has turned out to be one of the reliable sources of renewable energy, which requests extra transmission capacity and better methods for sustaining system reliability. As of now, doubly fed induction generator wind turbine is the most well-known wind turbine. This paper focuses on DFIG wind farm design using MATLAB/SIMULINK and also investigates the issues of the system stability of the DFIG wind turbine micro grid power system. This analysis includes the changes of voltage, current, real power and reactive power based on various conditions of the power system.

Application of seven-level neural space vector PWM in direct vector control system of doubly fed induction generator for wind turbine

This paper presents the direct vector control (DVC) technique of doubly fed induction generator (DFIG) with the application of seven-level neural space vector pulse width modulation (7L-NSVPWM). The mathematical model of the DFIG has been described. The descriptions of the 7L-SVPWM technique and neural networks (NNs) have been presented. The DVC control scheme with 7L-NSVPWM technique has been described. The simulation results of the DVC control with 7L-NSVPWM strategy have been performed, and the results of these simulations are presented and discussed.

Sub-synchronous Harmonic Impedance Analysis of Doubly-fed Induction Generator Wind Turbine

Abstract This paper researches the sub-synchronous harmonic impedance of doubly-fed induction generator (DFIG) wind turbine. For analyzing the harmonic impedances, additional harmonic voltage source is applied over the sub-synchronous frequency range and different operating conditions of the DFIG wind turbine are considered. Also, different mechanical parameter of the DFIG are changed for analyzing their influence on the harmonic impedances.

Comparative Study of Different Pitch Angle Control Strategies for DFIG Based on Wind Energy Conversion System

Abstract- This paper presents an advanced pitch angle control for large scale Wind Energy Conversion System (WECS) based on a Doubly-Fed Induction Generator (DFIG). Blade Pitch angle control is the extremely popular techniques for regulating the aerodynamic power of the wind turbine and minimize aerodynamic fatigue when the wind speed is higher than its rated value. The traditional control technique is based on the proper system modeling and analytical analysis of the transfer function which are not always available and the non-linearity of the control system. To overcome the problems in the traditional control, the adaptive fuzzy-PID control is proposed in this work. The process of the blade pitch control using adaptive fuzzy-PID control strategy is featured with nonlinearity, multi-variable, time variation and time delay. The simulation results are enclosed which prove the effectiveness of the auto-tuning adaptive fuzzy-PID (AF-PID) controller in improving the dynamic performance of the wind turbine (WT). This article emulated comparative analysis of 1.5 MW Doubly-fed induction generator wind turbine control strategies based on computer modeling in MATLAB/Simulink software.

An Accurate Forced Oscillation Location and Participation Assessment Method for DFIG Wind Turbine

With the integration of wind energy, the widely used doubly fed induction generator wind turbines (DFIG-WT) could induce Power System forced oscillations (FOs), which threaten the safety of power grid. In this paper, an accurate FOs location method is proposed to pinpoint sources of FOs to the specific components inside a DFIG-WT and a participation assessment method is proposed to evaluate the role of DFIG-WTs in the FOs event. Firstly, the energy structure of the DFIG-WT is constructed and the correspondence between the physical components and energy structure of the DFIG-WT is established. Thus, the sources of FOs can be located by the energy flow among the converter, wind turbine and induction generator. Furthermore, the port-controlled Hamiltonian (PCH) method is used to analyze the influence of external disturbances to the potential energy of DFIG-WT, based on which the participation factor of the DFIG-WT in FOs event can be defined. The simulation results demonstrate that the proposed method is able to locate the oscillation sources accurately and reveal the participation of the DFIG-WT in FOs events effectively.

Power quality enhancement in electricity grids with wind energy using multicell converters and energy storage

In recent years, the wind power industry is experiencing a rapid growth and more wind farms with larger size wind turbines are being connected to the power system. While this contributes to the overall security of electricity supply, large-scale deployment of wind energy into the grid also presents many technical challenges. Most of these challenges are one way or another, related to the variability and intermittent nature of wind and affect the power quality of the distribution grid. Power quality relates to factors that cause variations in the voltage level and frequency as well as distortion in the voltage and current waveforms due to wind variability which produces both harmonics and inter-harmonics. The main motivation behind work is to propose a new topology of the static AC/DC/AC multicell converter to improve the power quality in grid-connected wind energy conversion systems. Serial switching cells have the ability to achieve a high power with lower-size components and improve the voltage waveforms at the input and output of the converter by increasing the number of cells. Furthermore, a battery energy storage system is included and a power management strategy is designed to ensure the continuity of power supply and consequently the autonomy of the proposed system. The simulation results are presented for a 149.2 kW wind turbine induction generator system and the results obtained demonstrate the reduced harmonics, improved transient response, and reference tracking of the voltage output of the wind energy conversion system.

Retaining of Frequency in Micro-grid with Wind Turbine and Diesel Generator

This paper aims to compare the performance of frequency regulation with two control modes of controller including power control scheme and rotor speed control scheme. The frequency control in this research is based on the frequency droop control method but fuzzy logic is used to define the frequency droop coefficient. To compare the performance of these control modes, a simulation of a micro-grid with the existence of a group of doubly fed induction generator wind turbine system and a diesel generator is fulfilled in Matlab/Simulink. Simulation results indicated that the frequency in the micro-grid with two control schemes always remains in the operation range. With the power control scheme, the frequency in the micro-grid is smoother than that with the rotor speed control. Additionally, DFIG wind turbine with the power control scheme has a better performance in terms of electrical energy when compared to the rotor speed control scheme, and hence the cost of fuel used by diesel is less costly.

Wind farm simulations based on a DFIG machine using parallel programming

New computational techniques for simulating a large array of wind turbines are highly needed to model modern electrical grid networks. In this paper, an implementation of a doubly fed induction generator wind turbine model solver is proposed. This solver will run on an NVIDIA graphic processing unit, and it will be coded using the compute unified device architecture (CUDA). The implementation will integrate a linear time-invariant system represented by state-space matrices. It has been implemented a CUDA kernel capable of simulating many wind turbines in parallel with different wind profiles and using different configurations. Strategies such as optimizing memory access and overlapping data transfers with the kernel were used to obtain the results. The CUDA implementation reaches an occupancy of 95%, while simulating 500 wind turbines where each unit is subject to a different wind profile or using different configuration parameters.

Design and Analysis of Adaptive Sliding Mode with Exponential Reaching Law Control for Double-Fed Induction Generator Based Wind Turbine

<p>The main objective of this paper is to continue the development of activities of basic and applied research related to wind energy and to develop methods of optimal control to improve the performance and production of electrical energy from wind. A new control technique of Double fed induction generator for wind turbine is undertaken through a robust approach tagged nonlinear sliding mode control (SMC) with exponential reaching law control (ERL). The SMC with ERL proves to be capable of reducing the system chattering phenomenon as well as accelerating the approaching process. A nonlinear case numerical simulation test is employed to verify the superior performance of the ERL method over traditional power rate reaching strategy. Results obtained in Matlab/Simulink environment show that the SMC with ERL is more robust, prove excellent performance for the control unit by improving power quality and stability of wind turbine.</p>

Model Reduction of DFIG Wind Turbine System Based on Inner Coupling Analysis

The doubly-fed induction generator (DFIG) wind turbine system, which is composed of the wind turbine, generator, rotor-side converter, grid-side converter, and so on, is a typical multi-time scale system. The dynamic processes at different time scales do not exist in isolation. Furthermore, neglecting the coupling of parameters of different time scales to reduce the order of the model will lead to deviation between the simulation results and the actual results, which may not be suitable for power system transient analysis. This paper proposes an electromechanical transient model and an electromagnetic transient model of the DFIG wind turbine system that consider the interaction of multiple time-scale dynamic processes. Firstly, the paper applies the modal analysis method to explain the multi-time scale characteristics of the DFIG wind turbine system. Secondly, the variation in the eigenvalues of the DFIG wind turbine system before and after the order reduction and the coupling between variables and the system, as well as the coupling between variables of different time scales, are analyzed to obtain the preliminary 21-order simplified model. Thirdly, considering the weak coupling characteristics between the mechanical part and the electromagnetic part of the DFIG wind turbine system, the 21-order simplified model is decomposed into a 15-order electromagnetic transient model and a six-order electromechanical transient model on the basis of their time scales. Then, according to the balance between simulation time and simulation accuracy, the 14-order electromagnetic transient model and the 10 or 12-order electromechanical transient model are finally obtained. Finally, the rationality of the simplified models is verified by simulations under two large disturbance conditions, namely wind speed abrupt change and voltage sag. The obtained simplified models have reference significance for improving the simulation speed of a wind power grid-connected system and analyzing the internal mechanism of the DFIG wind turbine system’s stability.

Stochastic multi-objective optimal energy and reactive power dispatch considering cost, loading margin and coordinated reactive power reserve management

In the recent years, modern wind farms (WF) are being increasingly integrated in the power systems. Thanks to the capability curve of doubly-fed induction generator (DFIG) wind turbines, these modern WFs are able to separately supply active and reactive powers. Accordingly, by increasing the penetration of this kind of sources, both voltage stability and reactive power reserve (RPR) management of power system can be affected. This issue makes it important to propose a new methodology for optimal energy and reactive power dispatch in a system with integrated modern WFs in order to effectively take into consideration the capabilities of modern WFs in different aspects of power system operation. Under this perspective, this paper proposes a stochastic multi-objective optimal dispatch (SMO-OD) problem in the presence of modern WFs to make a techno-economic framework for the system operators (SOs). The proposed SMO-OD problem aims at minimizing expected payments of energy and reactive power markets, and maximizing expected RPR and loading margin (LM) in the presence of wind power generation uncertainty. This paper also contributes to the relevant literature by formulating a model which determines the RPR of modern WFs to be included in the management of total RPR of the power system. Also, a coordinated RPR (CRPR) scheme is proposed by using this model. The proposed model benefits from a detailed reactive power output model of the DFIG wind turbines in order to handle real-world power system operation. Two studies are considered in the proposed SMO-OD problem: (i) SMO-OD with uncoordinated RPR provision (SMO-OD-URPR), and (ii) SMO-OD with the CRPR provision (SMO-OD-CRPR). The proposed SMO-OD problem is applied to the IEEE 30-bus test system. Simulation results show that using the proposed model, a proper trade-off is made between technical and economic aspects of power system operation, and considerable LM and RPR are provided. In the proposed SMO-OD-CRPR problem, the value of expected RPR increases compared to SMO-OD-URPR problem, and the DFIG-based WF has more expected RPR to inject to grid under contingency or sudden increased load. Moreover, by increasing the wind penetration level, not only does the value of expected payments of energy and reactive power markets reduce, but also the value of expected LM and RPR increases.

Improvement Performances of Active and Reactive Power Control Applied to DFIG for Variable Speed Wind Turbine Using Sliding Mode Control and FOC

This paper deals with the Active and Reactive Power control of double-fed induction generator (DFIG) for variable speed wind turbine. For controlling separately the active and the reactive power generated by a DFIG, field oriented control (FOC) and indirect sliding mode control (ISMC) are presented. These non linear controls are compared on the basis of topology, cost, efficiency. The main contribution of this work based to the short time of response with excellent convergence and high decoupled between active and reactive power in one part and in the second part we define the benefit to use indirect model of DFIG to the conception of indirect sliding mode control by using the relationships between stator powers and rotor currents. The simulation results have shown good performances concerning the tracking of the references both in transient and steady state and prove the effectiveness of sliding mode control to track the given references using PWM inverter.

An Enhanced Control Strategy for Doubly-Fed Induction Generators Based on a Virtual Harmonic Resistor and Capacitor under Nonlinear Load Conditions

Harmonic amplification for doubly-fed induction generator wind turbine systems (DFIG WTSs) will occur due to the existence of non-linear loads and reactive power compensation installation, and grid voltage and total grid current at the point of common coupling (PCC) will be distorted. An impedance model is established to analyze the interaction between DFIG WTS, non-linear loads and weak grids. Harmonic current impact factor and harmonic voltage impact factor is proposed to analyze the impact of harmonic current source on total grid current and voltage at the PCC with different control strategies. A virtual harmonic resistor and capacitor method is adopted to reduce the harmonic voltage. An impedance-based analysis method is adopted to analyze the stability of the DFIG system. To achieve optimal control of harmonic voltage and harmonic current, a coordination factor is proposed to adjust the dynamic allocation for harmonic voltage and harmonic current at PCC. The experimental results demonstrate the effectiveness of the proposed control strategy.

Model‐free adaptive learning control scheme for wind turbines with doubly fed induction generators

The classical control mechanisms of the wind turbines are generally based on precise modelling approaches to ensure robust and effective interplay between the wind turbines and the main power grids in both autonomous and grid-connected modes. This study presents an innovative intelligent control system for the doubly fed induction generator wind turbines. The proposed system uses model-free control polices. The online controller is based on a policy iteration reinforcement learning paradigm along with an adaptive actor-critic technique. It is shown to be robust against the turbine's high non-linearities and stochastic variations in the input–output conditions. These are associated with single and double rotor doubly fed large-scale induction generators driven by wind turbines in the range of 5–7 MW. The performance of the controller is validated against challenging scenarios of coexisting undesired situations like severe wind changes with load excursions and abrupt shifts in the loads.

Short-Circuit Current Calculation and Harmonic Characteristic Analysis for a Doubly-Fed Induction Generator Wind Turbine under Converter Control

An accurate calculation of short-circuit current (SCC) is very important for relay protection setting and optimization design of electrical equipment. The short-circuit current for a doubly-fed induction generator wind turbine (DFIG-WT) under excitation regulation of a converter contains the stator current and grid-side converter (GSC) current. The transient characteristics of GSC current are controlled by double closed-loops of the converter and influenced by fluctuations of direct current (DC) bus voltage, which is characterized as high order, multiple variables, and strong coupling, resulting in great difficulty with analysis. Existing studies are mainly focused on the stator current, neglecting or only considering the steady-state short-circuit current of GSC, resulting in errors in the short-circuit calculation of DFIG-WT. This paper constructs a DFIG-WT total current analytical model involving GSC current. Based on Fourier decomposition of switch functions and the frequency domain analytical method, the fluctuation of DC bus voltage is considered and described in detail. With the proposed DFIG-WT short-circuit current analytical model, the generation mechanism and evolution law of harmonic components are revealed quantitatively, especially the second harmonic component, which has a great influence on transformer protection. The accuracies of the theoretical analysis and mathematical model are verified by comparing calculation results with simulation results and low-voltage ride-through (LVRT) field test data of a real DFIG.

Modelling and power control of grid-connected wind energy system

Wind energy generation has attracted great interests in recent years. Doubly Fed Induction Generator (DFIG) for wind turbines are largely deployed because variable-speed wind turbines have many advantages over fixed-speed generation such as increased energy capture, operation at maximum power point, improved efficiency, and power quality. This paper presents the operation and vector control of a Doubly-fed Induction Generator (DFIG) system where the stator is connected directly to a stiff grid and the rotor is connected to the grid through bidirectional back-to-back AC-DC-AC converter. The basic operational characteristics , mathematical model of the aerodynamic system and vector control technique which is used to obtain decoupled control of powers are investigated using the software Matlab/Simulink.

A fault ride through scheme for doubly fed induction generator wind turbine

ABSTRACTThis paper presents a coordinated control scheme for the doubly fed induction generator (DFIG) based wind turbine (WT) to enhance the fault ride through (FRT) capability. The coordinated FRT scheme includes: (1) an improved vector control strategy; (2) a crowbar protection circuit; (3) a DC-link chopper circuit, and their coordinated control. The improved vector control strategy introduces a compensation term reflecting the instantaneous stator voltage in order to limit rotor current during the voltage fault. The effectiveness of the proposed approach has been demonstrated through various simulation cases. The simulation results show that the coordinated scheme can not only improve the FRT capability of the DFIG WT, but also can minimise the occurrence of hardware circuits and reduce their effect on the DFIG WT.