Advances in actuation techniques for wind farm flow control

Offshore wind farms suffer substantial energy losses due to the interference of wind turbine wakes, with estimates indicating losses of approximately 10%. This thesis aims to advance the state of the art of wind farm flow control techniques for maximizing wind farm power performance. Wind farm flow control can be divided into three categories:...

Advances in Safety and Security of Cyber-Physical Systems: Sliding Mode Observers, Coalitional Control and Homomorphic Encryption

Without us realizing it, solutions for safety and security are present all around us. However, everyone has undoubtedly also experienced how inconvenient some safety and security measures can be. For example, think about security checks at the airport, the need to wear a bicycle helmet, or being asked to perform 2-factor authentication to log...

Pitch control for wind turbine load mitigation and enhanced wake mixing: A simulation and experimental validation study

The dissertation discusses different wind turbine control strategies that use pitch actuation to decrease the Levelized Cost of Energy (LCoE) of wind farms. This is achieved by either mitigating the loads experienced by individual turbines, or by enhancing wake mixing in turbines located within a wind farm. The latter strategy exploits the fact...

Closing the loop in model-based wind farm control

Open-loop wake steering inconsistently improves the energy yield of wind farms in field experiments in the literature. This thesis matures wind farm control technologies for power maximization in a model-based closed-loop framework towards real-world practical applicability. Firstly, open-loop wake steering is evaluated on a commercial onshore...

Wind turbine control: Advances for load mitigations and hydraulic drivetrains

In the last decades, tremendous efforts have been put in advancements of wind turbine technology by scientific research and industrial developments. One of the focal areas has been the upscaling of turbines to increase power capacity. However, by enlarging turbine sizes, the square-cube law dictates rising costs per unit of power capacity. To...

Towards closed-loop dynamical wind farm control: model development and control applications

Electricity consumption is increasing on a global level. In 2017, non-renewable energy sources such as crude oil, natural gas and coal provided 76% of the required energy, while 24% came from renewable sources such as hydro, wind and solar. Non-renewable sources are finite because they do not replenish rapidly enough relative to the rate at...

LQG and Gaussian process techniques: For fixed-structure wind turbine control

Wind turbines are growing bigger to becomemore cost-efficient. This does increase the severity of the vibrations that are present in the turbine blades, both due to predictable effects like wind shear and tower shadow, and due to less predictable effects like turbulence and flutter. If wind turbines are to become bigger and more cost-efficient,...

A tensor approach to linear parameter varying system identification

Control design for two-bladed wind turbines

In the past decades wind energy has evolved into a mature source of sustainable energy such that onshore wind turbines have become cost competitive with other fossil-based energy sources. Onshore wind energy, however, faces social resistance and a lack of available locations. Offshore wind energy, on the other hand, offers vast amounts of...

Data-driven wind plant control

Each wind turbine in a cluster of wind turbines (a wind power plant) can influence the performance of other turbines through the wake that forms downstream of its rotor. The wake has a reduced wind velocity, since the turbine extracts energy from the flow, and the obstruction by the wind turbine rotor causes increased turbulence. If another...

Identification of wind energy systems

In the next decades wind energy is expected to secure a firm share of the total energy production capacity in many countries. To increase competitiveness of wind power with other power sources it is essential to lower the cost of wind energy. Given the design of a turbine, this objective can be attained in several ways, for instance by...

Towards Data-Driven Control for Modern Wind Turbines

Further developments in data-driven control techniques for the load reduction of modern wind turbines can achieve an increased lifetime of components and make the scaling to larger rotor diameters possible, and therefore improve the cost effectiveness of modern wind turbines. Also the success of future rotor designs will heavily depend for their...