Dynamic Model Of Wind Turbine Research Articles

Generic Type 3 WT models: comparison between IEC and WECC approaches

The widespread use of renewable energies around the world has generated the need for new tools and resources to allow them to be properly integrated into current power systems. Power system operators need new dynamic generic models of wind turbines and wind farms adaptable to any vendor topology and which permit transient stability analysis of their networks with the required accuracy. Under this framework, the International Electrotechnical Commission (IEC) and the Western Electricity Coordinating Council (WECC) have developed their own generic dynamic models of wind turbines for stability analysis. Although these entities work in conjunction, the focus of each is slightly different. The WECC models attempt to minimise the complexity and number of parameters needed, while the IEC approach aims to optimise comparison with real turbine measurements. This study presents a detailed comparison between these two different approaches for modeling a Type 3 (i.e., DFIG) wind turbine in MATLAB/Simulink. Finally, several simulations are conducted, with which the consequences of the different approaches are evaluated. The results of this paper are of interest to power system operators as well as wind turbine manufacturers who require further assistance in adapting their specific models to the simplified versions provided by the International Committees.

Enforcement of Current Limits in DFIG-Based Wind Turbine Dynamic Models Through Capability Curve

This letter proposes analytical expressions to enforce stator and rotor current limits in DFIG-based wind turbine models using the DFIG capability curve (DFIG-CC)—DFIG stands for doubly-fed induction generator. Two other commonly used procedures to enforce limits are employed for comparison purposes. A 15-bus test system is used for simulations, which includes five wind turbine generators with plant-level controllers for both participation in frequency regulation through inertial response and voltage regulation. The results show that the proposed expressions are accurate and, unlike the commonly used procedures, they do not allow either significant over-current or significant underutilized reactive power for voltage regulation.

Field Validation of a Standard Type 3 Wind Turbine Model for Power System Stability, According to the Requirements Imposed by IEC 61400-27-1

The definition of standard dynamic wind turbine models for power system stability analysis has been under development in recent years. These standard models, also known as generic or simplified models, have been developed under the framework of a new international standard, IEC 61400-27-1, the first edition of which was published in February 2015. These models are simplified representations of complex systems, such as wind turbines. Hence, the wind power industry urgently needs validation in comparison with real measurements to verify the accuracy and corresponding usability of the models. This paper presents the validation of a generic doubly-fed induction machine wind turbine model, commonly known as Type 3, based on a measurement campaign carried out in a Spanish wind farm. The wind turbine has been subjected to six voltage dips with different characteristics, magnitude, and duration, as well as several wind turbine operating conditions. The real behavior of the wind turbine is compared with the simulated response provided by the corresponding generic dynamic wind turbine model produced by the manufacturer Gamesa . Furthermore, the validation guidelines recently issued by IEC 61400-27-1 have been implemented, and the most important validation errors have been analyzed.

ENGLISH

Doubly Fed Induction Generators (DFIG) are as the main generators which are used in the power generation systems of wind energy in Variable Speed-Constant Frequency (VSCF). Wind turbine model and dynamic mathematic model of DFIG have been presented in this article. Rotor currents control in internal loop and rotation speed in external loop have been accomplished according to the methods of Internal Model Control (IMC). A sample of Doubly Fed Induction Generators of VSCF with nominal capacity of 1.5 MW has been simulated in MATLAB software. The simulation results indicate quick dynamic response of system in different conditions and performance in hyper-synchronous and sub-synchronous speed.

Dynamic modeling of wind turbine based axial flux permanent magnetic synchronous generator connected to the grid with switch reduced converter

Abstract This paper studies the power electronic converters for grid connection of axial flux permanent magnetic synchronous generators (AFPMSG) based variable speed wind turbine. In this paper, a new variable speed wind turbine with AFPMSG and Z-source inverter is proposed to improve number of switches and topology reliability. Besides, dynamic modeling of AFPMSG is presented to analyze grid connection of the proposed topology. The Z-source inverter controls maximum power point tracking (MPPT) and delivering power to the grid. Therefore other DC–DC chopper is not required to control the rectified output voltage of generator in view of MPPT. As a result, the proposed topology requires less power electronic switches and the suggested system is more reliable against short circuit. The ability of proposed energy conversion system with AFPMSG is validated with simulation results and experimental results using PCI-1716 data acquisition system.

Wind Turbine Model and Observer in Takagi-Sugeno Model Structure

Based on a reduced-order, dynamic nonlinear wind turbine model in Takagi- Sugeno (TS) model structure, a TS state observer is designed as a disturbance observer to estimate the unknown effective wind speed. The TS observer model is an exact representation of the underlying nonlinear model, obtained by means of the sector-nonlinearity approach. The observer gain matrices are obtained by means of a linear matrix inequality (LMI) design approach for optimal fuzzy control, where weighting matrices for the individual system states and outputs are included. The observer is tested in simulations with the aero-elastic code FAST for the NREL 5 MW reference turbine, where it shows a stable behaviour in turbulent wind simulations.

Performance Analysis and Control of Double Fed Induction Generator Using Modified Direct Power Control Scheme during Nonlinear Loading

Renewable energy resources has given rise to the systems that transmit and distribute electricity. Recent developments in the wind energy as distribution generation systems in the distribution networks is gaining popularity as a new sources of energy. The integration of renewable energy in to the power system causes severe challenges for the control and protection of the distributed system. A careful operation and design of distribution systems with renewable energy resources should be carried out. This paper describes the dynamic modeling and simulation results of DFIG wind turbine during nonlinear loading. During nonlinear loading the overall performance gets considerably degraded due to the effect of negative sequence component and also the power produced by the DFIG gets considerably derated. To eliminate this effect a suitable control technique should be applied. Direct Power Control (DPC) scheme is implemented along with Proportional Integral (PI) controller. The DPC directly controls the Stator active and reactive powers, while the PI controllers is used to regulate the positive and negative sequence component. The proposed DPC-PI control strategy is verified by the simulation results during nonlinear loading. The models have been developed by means of MATLAB/SIMULINK software.

Dynamic analysis of wind turbine drive train subjected to nonstationary wind load excitation

The dynamic analysis of wind turbine drive train is presented in this paper. A typical wind turbine drive train consists of a rotor, gearbox and generator. The dynamic modelling of epicyclic gearbox that exists in wind turbine is challenging due to the fact that it has both rotating and orbiting gears. The dynamic equations of motion are obtained based on the rigid multibody modelling with discrete flexibility approach by Lagrange’s formulation. The dynamic model accounts for the time varying gear tooth mesh stiffness, linear stiffness of bearings and torsional shaft stiffness. The aerodynamic torque that a wind turbine drive train subjected to, is modelled based on the simplified method for load calculation in wind turbine, Danish Standard DS472. The characteristic load value acting per unit length at the two-thirds length of the blade is used for calculating the total load of the torsional moment. The vibration signals that are obtained from wind turbine drive train are nonlinear and nonstationary in nature. This is due to the fact that the applied torque load on drive train is nonlinear and nonstationary in nature. The coupled dynamic model of 18 degrees of freedom is solved for responses in time and frequency domains for some nonstationary wind load realizations. The dynamic responses of the system, contact forces between gear tooth pairs in time and frequency domains are obtained numerically. The study envisages that this dynamic model of wind turbine drive train is very useful for subsequent studies on condition monitoring.

Research on IEC Type3 Wind Turbine Generator

The dynamic model of DFIG for power flow calculation and transient simulation is proposed and becoming a hot spot of research. Based on the principle of DFIG model which is newly released by the International Electrotechnical Commission (IEC), analyzes model structure and the control block. The type 3 wind turbine generator (WTG) is implemented in PSCAD environment, Case studies under both normal and grid fault conditions are done with the implemented IEC generic models of type3 WTG, simulation results of IEC type3 WTG are compared with the full order model .The case study results show that the IEC generic models of Type3 WTG can correctly represent the performances of Type3 WTG under both normal and fault conditions, the validation of the model are verified, the model will promote the standardization of domestic wind turbine model, and provide correct and effective dynamic model of wind turbine for study of the wind power integration into grid.

基于差动轮系调速的风力发电机的动力学建模与分析

对基于无级调速原理的风力发电机动力学建模，改变传统风力发电机的齿轮箱传动比固定而采用电子方法实现变速恒频的特性，通过增加差动轮系的自由度，采用机械调速方式进行前端调速，使输出转速与转矩恒定，达到变速恒频的目的。以实现调速功能的差动轮系为主要研究对象，将整个风力发电机传动链简化成三个部分：行星架输入轴、太阳轮输出轴和齿圈调速轴，并运用拉格朗日方程和差动轮系转速约束关系，建立动力学方程。结合风力发电机并网要求，此外还研究了该情形下的动力学关系，将并网后的动力学问题即转化为：输出转速恒定条件时，可变的风轮转矩作用下，调速电机的调速问题。Based on the principle of stepless speed regulation, dynamic modeling of wind turbine has been done. Having changed fixed transmission ratio characteristic of gearbox in traditional wind turbines and the variable speed constant frequency characteristic realized by electronic method, the freedom of differential gear train is increased and the mechanical means have been used for the fore-end speed regulation in order to achieve constant output speed and torque. Taking the diffe-rential gear train as the main learning object, in this paper the wind turbine transmission chain is divided into three parts: planet carrier input shaft, sun wheel output shaft and ring gear speed- regulation shaft, and dynamic equations are established using the Lagrange equation and the speed constraint relations of differential gear train. Therefore, to satisfy the grid-connected requirement, the dynamic relationship in this circumstance is also learned. The dynamic problem can be transformed into the speed-regulation problem of speed-regulation motor under the variable wind turbine torque to achieve constant output speed.

Code Shift: Grid Specifications and Dynamic Wind Turbine Models

Grid codes (GCs) and dynamic wind turbine (WT) models are key tools to allow increasing renewable energy penetration without challenging security of supply. In this article, the state of the art and the further development of both tools are discussed, focusing on the European and North American experiences.

Analysis of Short-Term Energy Storage for Midsize Hydrostatic Wind Turbine1

This paper presents a novel method of capturing more energy from the wind using short-term energy storage in a hydrostatic wind turbine. A hydrostatic transmission (HST) not only provides reliable operation but also enables energy management features like energy regeneration using hydraulic accumulators. In this study, turbulence-induced wind transients occurring near the rated power are exploited to extract more energy from the wind. Wind characteristics are analyzed to develop models to quantify the energy losses due to the wind turbulence and the potential energy gains from the short-term energy storage. A dynamic simulation model of the hydrostatic wind turbine and the proposed energy storage system is developed. A rule-based control strategy for the energy storage is proposed. Results show that in a 50 kW hydrostatic wind turbine, the annual energy production (AEP) can be increased by 4.1% with a 60 liter hydraulic accumulator.

Reduction of Wind Turbine Torque Fluctuation Using Individual Pitch Control Based on Edgewise Moment

In order to eliminate the nonuniform force on the wind rotor caused by wind shear, tower shadow and turbulence and smooth the torque fluctuation of the wind turbine and the unbalanced loads on the wind turbine, a new individual pitch control strategy based on edgewise moment using single neuron PID controller is proposed. That is, the presented control strategy directly controls the blade edgewise moment generated by aerodynamic force. At the same time, to simulate the wind turbine loads, a dynamic model of three-bladed upwind horizontal axis wind turbine is built. Thus, the influence rules of the wind turbine torque fluctuation are deduced at length. Finally, to verify the effectiveness of the proposed individual pitch control system with the single neuron PID controller, the 2MW wind turbine generator system is modeled and simulated. The performance of the controller is illustrated its capability of not only reducing the wind turbine fluctuation, but also smoothing the fluctuation of the flapwise moment, the yaw moment and the tilt moment.

Robustness investigation of the linear multi-variable control technique for power management of DFIG wind turbines

Variable speed wind turbines are widely used in the modern power industry. These turbines that are usually driven by doubly fed induction generators (DFIGs) contain two groups of controlling variables; mechanical variables like pitch angle and electrical variables like rotor voltage. During the turbine operation, with variable wind velocity, power must be managed in two regimes; power optimisation and power limitation. In the current research, initially a non-linear simulation, based on the general wind turbine dynamic model is presented. Then, the desired controllers for both pitch angle and generator voltage components are constructed. After designing the controller, in order to investigating the controller robustness, time-varying variables like wind velocity, grid voltage amplitude, and blades pitch angle are changed from the nominal values. By surveying the simulation results it is seen that the presented control method can comply the desired targets in turbine power management.

Continuous wind speed models based on stochastic differential equations

This paper proposes two general procedures to develop wind speed models based on stochastic differential equations. Models are intended to generate wind speed trajectories with statistical properties similar to those observed in the wind speed historical data available for a particular location. The developed models are parsimonious in the sense that they only use the information about the marginal distribution and the autocorrelation observed in the wind speed data. Since these models are continuous, they can be used to simulate wind speed trajectories at different time scales. However, their ability to reproduce the statistical properties of the wind speed is limited to a time frame of hours since diurnal and seasonal effects are not considered. The developed models can be embedded into dynamic wind turbine models to perform dynamic studies. Statistical properties of wind speed data from two real-world locations with significantly different characteristics are used to test the developed models.

Performance Assessment of Micro and Small-Scale Wind Turbines in Urban Areas

This paper addresses some general issues related to the difficulties and uncertainties during the assessment and characterization of micro and small-scale wind-based generation in urban areas. This paper proposes four generic wind turbine models, which could be used for the analysis and selection of optimal wind turbines in target applications, as they accurately represent the range of wind turbines currently available on the market. The analysis in this paper compares results for the expected annual energy outputs and cost-benefit analysis obtained using steady state and dynamic wind turbine models of actual and generic micro/small wind turbines, applying both low-resolution and high-resolution measurements of available wind energy resources. The presented results demonstrate the significance of the accurate assessment of wind resources in urban areas, as well as the importance of the correct modeling of wind turbine characteristics. It is shown that substantial errors, typically overestimating wind turbine performance, are obtained if standard assumptions and current recommendations are used for the analysis of wind turbine performance.

Increasing Wind Energy Penetration Level by Using Pumped Hydro Storage in Island Micro-Grid System

Ramea is a small island in southern Newfoundland. Since 2004, it has a wind-diesel hybrid power system to provide power for approximately 600 inhabitants. In this paper, wind speed data, load data, and sizing of pumped hydro system at Ramea, Newfoundland are presented. The dynamic model of wind turbine, pumped hydro system, and diesel generator are included in this paper. The dynamic model is simulated in SIMULINK/MATLAB to determine the system voltage and frequency variation and also to visualize different power outputs. Sizing of pumped hydro system indicates that a 150-kW pumped hydro storage system can be installed in Ramea to increase the renewable energy fraction to 37% which will reduce non-renewable fuel consumption on this island. Also, it is found that a pumped hydro energy storage system for Ramea is a much better choice than a hydrogen energy storage system. Such a system will have a higher overall efficiency and could be maintained using local technical expertise, therefore, a more appropriate technology for Ramea.

A Coherency-Based Equivalent Model of a Large Scale Wind Farm

With increasing installation capacity and wind farms penetration, wind power plays more important role in power systems, and the modeling of wind farms has become an interesting research topic. In this paper, a coherency-based equivalent model has been discussed for the doubly fed induction generator (DFIG). Firstly, the dynamic models of wind turbines, DFIG and the mechanisms are briefly introduced. Some existing dynamic equivalent methods such as equivalent wind model, variable speed wind turbine model, parameter identification method and modal equivalent method to be used in wind farm aggregation are discussed. Then, considering wind power fluctuations, a new equivalent model of a wind farm equipped with doubly-fed induction generators is proposed to represent the interactions of the wind farm and grid. The method proposed is based on aggregating the coherent group wind turbines into an equivalent one. Finally, the effectiveness of the equivalent model is demonstrated by comparison with the wind farm response obtained from the detailed model. The dynamic simulations show that the present model can greatly reduce the computation time and model complexity.

Adaptive Variable Speed Control of Wind Turbines

The uncertain and random characteristics of wind energy make the problem of wind turbine control interesting and challenging. This work investigates an adaptive method for variable speed control of wind turbines under varying operation conditions. For fixed-speed operation of wind turbines, maximum power conversion can be achieved only at a particular wind speed, thus variable speed control of wind turbines is of practical interest in enhancing wind turbine operating efficiency over wide wind speeds. Based on the nonlinear dynamic model of wind turbine, adaptive algorithms are developed in accommodating unknown system parameter uncertainties. This method is shown to be able to achieve smooth and effective tracking of rotor angular speed to capture maximum wind energy. The effectiveness and adaptation of the proposed approach is validated via numerical simulation.

Large Wind Turbine Dynamic Modeling and Simulation

The system produces strenuous vibration when the wind turbine is operating, it will be a great impact on running precision and components’ life of the whole system, the theoretical study of the research of wind turbine’s vibration is incomplete because of the complexity of the wind turbine’s structure and operating environment, as well as the difficulty of theoretical analysis. In this paper, the FAST established dynamic model of wind turbine, and preliminarily study the establishment of the wind turbine drive system model with multi-body dynamics software, finally dynamic response have been analyzed that based on the establishment of whole wind turbine model, which laid the foundation for wind turbine dynamic characteristic and the system’s optimal design.