Wind Turbine Controls for Farm and Offshore Operation

Development of advanced control techniques is a critical measure for reducing the cost of energy for wind power generation, in terms of both enhancing energy capture and reducing fatigue load. There are two remarkable trends for wind energy. First, more and more large wind farms are developed in order to reduce the unit-power cost in installation, operation, maintenance and transmission. Second, offshore wind energy has received significant attention when the scarcity of land resource has appeared to be a major bottleneck for next level of wind penetration, especially for Europe and Asia. This dissertation study investigates on several wind turbine control issues in the context of wind farm and offshore operation scenarios. Traditional wind farm control strategies emphasize the effect of the deficit of average wind speed, i.e. on how to guarantee the power quality from grid integration angle by the control of the electrical systems or maximize the energy capture of the whole wind farm by optimizing the setting points of rotor speed and blade pitch angle, based on the use of simple wake models, such as Jensen wake model. In this study, more complex wake models including detailed wind speed deficit distribution across the rotor plane and wake meandering are used for load reduction control of wind turbine. A periodic control scheme is adopted for individual pitch control including static wake interaction, while for the case with wake meandering considered, both a dual-mode model predictive control and a multiple model predictive control is applied to the corresponding individual pitch control problem, based on the use of the computationally efficient quadratic programming solver qpOASES. Simulation results validated the effectiveness of the proposed control schemes. Besides, as an innovative nearly model-free strategy, the nested-loop extremum seeking control (NLESC) scheme is designed to maximize energy capture of a wind farm under both steady and turbulent wind. The NLESC scheme is evaluated with a simple wind turbine array consisting of three cascaded variable-speed turbines using the SimWindFarm simulation platform. For each turbine, the torque gain is adjusted to vary/control the corresponding axial induction factor. Simulation under smooth and turbulent winds shows the effectiveness of the proposed scheme. Analysis shows that the optimal torque gain of each turbine in a cascade of turbines is invariant with wind speed if the wind direction does not change, which is supported by simulation results for smooth wind inputs. As changes of upstream turbine operation affects the downstream turbines with significant delays due to wind propagation, a cross-covariance based delay estimate is proposed as adaptive phase compensation between the dither and demodulation signals. Another subject of investigation in this research is the evaluation of an innovative scheme of actuation for stabilization of offshore floating wind turbines based on actively controlled aerodynamic vane actuators. For offshore floating wind turbines, underactuation has become a major issue and stabilization of tower/platform adds complexity to the control problem in addition to the general power/speed regulation and rotor load reduction controls. However, due to the design constraints and the significant power involved in the wind turbine structure, a unique challenge is presented to achieve low-cost, high-bandwidth and low power consumption design of actuation schemes. A recently proposed concept of vertical and horizontal vanes is evaluated to increase damping in roll motion and pitch motion, respectively. The simulation platform FAST has been modified including vertical and horizontal vane control. Simulation results validated the effectiveness of the proposed vertical and horizontal active vane actuators

Quantitative Change Analysis of Undisturbed Lands in Eastern South Dakota: 2012-2021

The actual rate of loss of undisturbed prairie and woodland in eastern South Dakota is unknown, and the landscape composition of the region continues to change. Undisturbed land is land with no proven prior cropping or other disturbance history. Agriculture, development, recreation, and other land use practices create disturbances resulting in the further conversion of undisturbed prairies and woodlands. Previous work by South Dakota State University (SDSU) quantified the remaining undisturbed land in eastern South Dakota as of 2012 (Bauman et al 2016). Farm Service Agency (FSA) common land unit (CLU) and National Agricultural Imagery Program (NAIP) imagery were the primary data used by SDSU to quantify undisturbed land as of 2012. Analysis was then conducted utilizing South Dakota Natural Resource Conservation Service (NRCS)derived Light Detecting and Ranging (LiDAR) imagery to determine additional areas of disturbance not previously detected with other methods. The objective of our study was to quantify the rate of conversion of Potentially Undisturbed Land between 2012-2021, using the SDSU Potentially Undisturbed Land results of the 2012 analysis as a baseline. Undisturbed land is defined as not being cultivated or mechanically disrupted (Bauman et al. 2016). Our analysis revisited previously designated polygons where LiDAR indicated a change in land use. Images containing land use change detected by LiDAR were contrasted with National Agricultural Imagery Program (NAIP) imagery to determine if the conversion of the land was prior or post 2012. Any LiDAR-indicated land conversion prior to 2012 was not included in our analysis. Once we determined the date of conversion for the LiDAR data, we then analyzed the remaining undisturbed land tracts to determine if additional conversion occurred after 2012. The total land area in these counties is 9,164,826 hectares (22,646,780 acres), of which 1,946,936 hectares (4,810,985 acres) or 21% was considered potentially undisturbed as of 2012. Our analysis concluded that an additional 56,561 hectares (139,766 acres) of previously undisturbed land in eastern South Dakota was converted between 2012 and 2021. Undisturbed prairies are complex ecosystems with a myriad of above and below ground biotic and abiotic components and are believed to be irrecoverable once they have been converted to other land use. Conversion of undisturbed lands in eastern South Dakota is, therefore, irreversible. For perspective, our data suggests an average rate of conversion of over 1,214 hectares (3,000 acres) per county over this 9-year period, or roughly 134 hectares (333 acres) per county per year

Design Optimization of Wind Energy Conversion Systems with Applications

Modern and larger horizontal-axis wind turbines with power capacity reaching 15 MW and rotors of more than 235-meter diameter are under continuous development for the merit of minimizing the unit cost of energy production (total annual cost/annual energy produced). Such valuable advances in this competitive source of clean energy have made numerous research contributions in developing wind industry technologies worldwide. This book provides important information on the optimum design of wind energy conversion systems (WECS) with a comprehensive and self-contained handling of design fundamentals of wind turbines. Section I deals with optimal production of energy, multi-disciplinary optimization of wind turbines, aerodynamic and structural dynamic optimization and aeroelasticity of the rotating blades. Section II considers operational monitoring, reliability and optimal control of wind turbine components

Wind Energy Management

The book "Wind Energy Management" is a required part of pursuing research work in the field of Renewable Energy at most universities. It provides in-depth knowledge to the subject for the beginners and stimulates further interest in the topic. The salient features of this book include: - Strong coverage of key topics - User friendly and accessible presentation to make learning interesting as much as possible - Its approach is explanatory and language is lucid and communicable - Recent research papers are incorporate

The Role of Active Flow-Control Devices in the Dynamic Aeroelastic Response of Wind Turbine Rotors

The significance of wind as a renewable source of power is growing with the increasing capacity of individual utility-scale wind turbines. Contemporary wind turbines are capable of producing up to 8 MW and consequently, their rotor sizes are rapidly growing in size. This has led to an increased emphasis on studies related to improvements and innovations in load-control methodologies. Most often than not, controlling the loads on an operational turbine is a precarious scenario, especially under high wind loading. The up-scaling of turbine rotors would thus benefit from a rationale change in load control through methodologies such as variable-speed stall, flexo-torsional adaptive blades, and active flow-control devices. This thesis work extends the capabilities of an aeroelastic code to provide a platform to analyze wind turbines with flow-control devices as active load control techniques. It also explores the effectiveness of such devices under rapid load-control scenarios relevant to benchmark turbines. Pre-determined rapid control actions such as pitching and trailing-edge flap actuation are implemented under nominal operating conditions. The benchmark turbine designed by National Renewable Energy Laboratory (NREL), which is an upwind three-bladed rotor rated at 5 MW forms the test bed for the current thesis study. The goal is to obtain an overall understanding of the aeroelastic rotor response of utility-scale wind turbines under rapid control actions, paying special attention to the power of actuation

U.S. Department of Energy Workshop Report - Research Needs for Wind Resource Characterization

This workshop brought the different atmospheric and wind technology specialists together to evaluate research needs for wind resource characterization

Design Optimization of Wind Energy Conversion Systems with Applications

Modern and larger horizontal-axis wind turbines with power capacity reaching 15 MW and rotors of more than 235-meter diameter are under continuous development for the merit of minimizing the unit cost of energy production (total annual cost/annual energy produced). Such valuable advances in this competitive source of clean energy have made numerous research contributions in developing wind industry technologies worldwide. This book provides important information on the optimum design of wind energy conversion systems (WECS) with a comprehensive and self-contained handling of design fundamentals of wind turbines. Section I deals with optimal production of energy, multi-disciplinary optimization of wind turbines, aerodynamic and structural dynamic optimization and aeroelasticity of the rotating blades. Section II considers operational monitoring, reliability and optimal control of wind turbine components