General model for representing variable speed wind turbines in power system dynamics simulations

As a result of increasing environmental concern, increasing amounts of electricity are generated from renewable sources. One way of generating electricity from renewable sources is to use wind turbines. A tendency to erect more wind turbines can be observed. As a result of this, in the near future wind turbines may start to influence the behavior of electrical power systems. To investigate the impact of increasing wind turbine penetration, power system dynamics studies need to be carried out. To this end, power system dynamics simulation software is used, in which wind turbine models must be integrated to enable the investigation of increasing wind turbine penetration on power system behavior. If wind turbine models are to be integrated into power system dynamics simulation software, it must be possible to calculate the initial conditions of the dynamic model from load flow data to be able to initialize the dynamic simulation correctly. In this paper, a solution to this problem is presented.

This paper investigates the possibilities for frequency support by synthetic inertia from variable speed wind turbines. A model for representing synthetic inertia in PSS/E (Power System Simulator for Engineering) has been developed. It allows the user to relatively simple implement different control strategies to find the most suitable strategy for a particular power system. Furthermore, it can be used regardless of the existence of wind turbine models in the power system model and is connected separately to any arbitrary bus in the power system. The results from the simulations show that the frequency nadir is reduced when implementing frequency support by synthetic inertia from wind turbines. As the wind power integration increases the frequency nadir is further improved when wind turbines can provide synthetic inertia. Regarding recovery, the results indicates that in order to minimise the risk of an under-frequency event the energy should be taken during a frequency overshoot and/or distributed in time, i.e. not all wind power plants should recover at the same time. However, these studies of synthetic inertia provided by wind turbines are still in the early stage and further work will be performed.

High penetration of wind power into power systems is likely to cause difficulties in maintaining system frequency, as in contrast to conventional synchronous generators, variable speed wind turbines (VSWTs) do not directly contribute to system inertia. To overcome this issue, it has been proposed to emulate inertia by VSWTs by extracting the kinetic energy of the turbine rotor. However, proper designing of the inertia emulating controller is essential for the optimal use of the energy potential and safe operation of the wind turbine. Some of the common controller concepts used for inertia emulation have inherent weaknesses, limiting the frequency support provided by VSWTs. This paper highlights these design considerations by simulating the inertial responses provided by a typical controller. To overcome the identified issues, a new controller design is proposed. Its capability to provide an improved frequency response while reducing the adverse impacts on the turbine rotor is demonstrated.

Synthetic inertial frequency response has attracted increasing attention due to the paradigm shift in power generation from synchronous generators toward wind turbines. This paper presents a novel nonlinear controller to enable inertial response of a variable speed wind turbine (VSWT). The VSWT has a nonlinear model which cannot efficiently be dealt with by linear control techniques as it may experience large deviations from its operating point during the frequency support period. To design the controller, a nonlinear model for the wind turbine together with power system is utilized. The output power of the wind turbine is expressed in terms of the state variables, and its exact Taylor series expansion is used in control design procedure. A regular controller is first designed based on the input–output feedback linearization approach. Then, the regular controller is replaced by an adaptive one to accommodate parameter variations of VSWT. The proposed controller is then embedded in the detailed model of the VSWT in MATLAB/Simulink environment. Extensive investigations, including the effects of different controller parameters, are carried out. Impacts of the most important practical operational constraints in the VSWT inertia response are also analyzed. Results verify the superiority and appropriateness of the proposed controller.

In this paper, a functional structure of a wind energy conversion system is introduced, before making a comparison between the two typical wind turbine operating schemes in operation, namely constant-speed wind turbine and variable-speed wind turbine. In addition, the modeling and dynamic behavior of a variable speed wind turbine with pitch control capability is explained in detail and the turbine performance curves are simulated in the MATLAB/Simulink.

Power flow calculation is a basic tool for power systems operation and control. Considering static frequency regulation characteristics of power systems, dynamic power flow (DPF) gives more precise results of system operation with frequency deviation than conventional power flow. The increasing penetration of wind energy into power grid makes it necessary to take wind power into consideration in DPF calculation. The operational traits and frequency regulation characteristics of major types of wind turbines are discussed, including fixed speed wind turbines and variable speed wind turbines with integrated control strategy combining over-speed control and droop control. With the primary frequency regulation characteristics of wind turbines, a simplified DPF algorithm is proposed in this study for power systems integrating wind power generation. The IEEE 30-bus system is modified to verify the proposed method considering different levels of wind power penetration.

To study the on grid wind turbine generator made in china, three types of horizontal axis three-blade wind turbine generator were researched. The design of wind turbine and the factors which influence the property of the wind wheel were studied. The mathematical model and operation principle of wind turbine with squirrel cage induction generator, doubly-fed induction generator and permanent magnet synchronous generator were studied. The operation conditions of the wind turbine generators in Dabancheng wind farm were investigated. The conclusion is that all the three types of wind turbine generators can be used well according the wind condition of the wind farm. The variable speed wind turbine with doubly-fed induction generator and with permanent megnet synchronous generator have less influence to the power system and they can recover the power generation easier while grid fault is cleared compared with the wind turbine with squrrel-cage induction generator.

Many large wind farms have employed doubly fed induction generator (DFIG) variable speed wind turbines. These require accurate models of doubly fed induction generator wind turbines and their associated control and protection circuits. The goal of this paper is to study the theory and control for the doubly-fed induction generator (DFIG) based wind turbine, and further establish its model by using mathematical formulas. The work utilized the power system analysis software PSCAD / EMTDC, which can quickly and accurately show the simulation results.

Prediction of wake and output power for an offshore wind turbine under various wind conditions is essential to maximize energy generation and minimize wake effects. In previous studies, deep learning (DL) models developed using high-fidelity computational fluid dynamics (CFD) simulation results have demonstrated high accuracy and efficiency in predicting the wake characteristics and output power of offshore wind turbines. However, these existing DL models were typically developed for specific types of wind turbines, which cannot be directly used for a new turbine type. Development of a new DL model relying solely on simulation data from a new wind turbine would waste the valuable information contained in previous datasets and existing DL models, leading to increased computational costs for data collection. To address this issue, this paper aims to leverage a previously established simulation dataset and a pre-trained DL model for a wind turbine to develop a new model for another type of wind turbine. The proposed method requires only a small number of new simulations for model development using transfer learning with fine-tuning and model-agnostic meta-learning (MAML), thereby enhancing computational efficiency. The results demonstrate that the models developed using fine-tuning and MAML achieve lower prediction errors and less model training time compared to those trained directly on new wind turbine data. Furthermore, the model trained using MAML outperforms the fine-tuning model when the dataset size is extremely small, while the fine-tuning model has lower prediction errors with relatively larger datasets.

Extensive model validation for generic IEC 61400-27-1 wind turbine models

This article reviews the design of algorithms for individual pitch control in the case of variable speed turbines. The aim of the designed control algorithm is to improve the power quality and to reduce voltage flicker. A simulation model of variable speed wind turbine was developed with the simulation tool of PSCAD/EMTDC. This article compared the individual pitch action and the collective pitch action, which is the same for all three blades, is calculated by means of a standard classical PI-based controller. The simulation result indicates that compared with the flicker coefficient of PI controlled wind turbine, the variable-speed wind turbines equipped with individual pitch controller, exhibit good behavior with respect to output power and voltage flicker, especially for 3P frequency reduction. Thereby, the variable-speed wind turbine with individual pitch controller will produce lower voltage flicker.

A novel approach for robust control design of hidden synthetic inertia for variable speed wind turbines

As wind power penetration into power systems increases, it poses a growing challenge to power system operation and stability. This is partly because wind power is highly time variable and cannot inherently contribute to power system frequency regulation. The provision of frequency support from wind turbines under changing wind conditions is examined in this paper. A simplified variable speed wind turbine model is developed. A modified turbine controller to deliver inertial and droop response is proposed. The interaction between inertial and droop response from wind turbines is examined under varying wind.

The present paper has two main objectives: (1) to create a digital twin of an onshore wind turbine to provide to the owner of the wind farm a tool for continuous tracking of accumulated fatigue damage and evaluation of alternative operation strategies; (2) to perform the first tasks for the creation a reliable numerical of a floating wind turbine to simulate experimental data for the testing of monitoring tools on this type of wind turbines. A numerical model of an onshore wind turbine was created with FAST software developed by the US National Renewable Energy Laboratory (NREL). The structural and mechanical properties of the structure were calculated from the geometric properties of the tower and blades. The aerodynamic properties of different sections of the blades were computed with 2D models created with ANSYS Fluent. Having the wind turbine fully characterised, the control mechanisms were calibrated using data from the manufacturer catalogues. Numerous time series of wind excitation for different operation conditions were generated, and the structural response computed. Additionally, the Supervisory Control and Data Acquisition (SCADA) operating in parallel with a series of extensometers and accelerometers located in strategic points along a real wind turbine tower and blades provided a full description of the internal forces in both locations and the estimation of the modal properties for different operating conditions. Both measured and simulated response allowed the identification and validation of structural dynamic properties and static and dynamic internal loads. In spite of several approximations and simplifications, the results obtained with the numerical model were in good agreement with the ones measured in the field.

Ash behavior in power systems can have a significant impact on the design and performance of advanced power systems. The Energy & Environmental Research Center (EERC) has focused significant effort on ash behavior in conventional power systems that can be applied to advanced power systems. This initiative focuses on filling gaps in the understanding of fundamental mechanisms of ash behavior that has relevance to commercial application and marketable products. This program develops methods and means to better understand and mitigate adverse coal ash behavior in power systems and can act to relieve the U.S. reliance on diminishing recoverable oil resources, especially those resources that are not domestically available and are fairly uncertain.