Pseudo-LIDAR data analysis and feed-forward wind turbine control design

To investigate potential improvement in wind turbine control employing LIDAR measurement, pseudo-LIDAR wind speed data is produced with Bladed using a designed sampling strategy, and assessed with preliminary frequency-domain analysis. A model-inverse feed-forward controller is adapted to combine with feedback control so as to enhance pitch control performance at high wind speed. This controller is applied to an industrial-scale 5MW wind turbine model and the control performance is compared with a baseline feedback controller. Simulation study demonstrates that the combined feed-forward/feedback control scheme has improvements in reducing pitch angle variation and reduction of load relevant metrics

Review of LIDAR-assisted Control for Offshore Wind Turbine Applications

This is the final version. Available on open access from IOP Publishing via the DOI in this recordEERA DeepWind Offshore Wind R&D Conference 19 - 21 January 2022, Trondheim, NorwayNacelle-mounted, forward-facing Light Detection and Ranging (LIDAR) technology is able to provide knowledge of the incoming wind so that wind turbines can prepare in advance, through feedforward control. LIDAR can aid in improving wind turbine performance across the full operating range, assisting with torque control in below rated wind speeds, pitch control in above rated wind speeds and yaw control for correctly aligning the turbine rotor with the incoming wind direction. The motivations are for decreasing structural loads, resulting in reduced maintenance and extended lifetimes of turbines and their components, and increasing power capture, both of which can lead to reductions in the levelised cost of energy. This paper provides a review of control strategies that have been employed for LIDAR-assisted turbine control. This paper reviews the computational and practical studies that have been performed for both bottom-fixed and floating turbines and the journey that the field has undertaken since its conceptualisation. Detail is provided of the key differences between fixed and floating offshore turbine dynamics. The paper concludes with guidance for future work within the field, with a focus on floating turbines, as the extent of the literature is scarce when compared to bottom-fixed. Suggestions are offered for how the future studies can better account for the current and future industry landscape. Opportunities for testing of LIDAR-assisted floating turbine control in the field, its benefits for floating substructure design, and the steps needed to be taken to ensure its increased utilisation on industrial projects are also discussed.Engineering and Physical Sciences Research Council (EPSRC)Natural Environment Research Council (NERC

Fault-tolerant load reduction control for large offshore wind turbines

Offshore wind turbines suffer from asymmetrical loading (blades, tower etc.), leading to enhanced structural fatigue. As well as asymmetrical loading different types of faults (pitch system faults etc.) can occur simultaneously, causing degradation of load mitigation performance and enhanced fatigue. Individual pitch control (IPC) provides an important method to achieve mitigation of rotor asymmetric loads, but this may be accompanied by a resulting enhancement of pitch movement leading to increased possibility of pitch system faults, which negative effects on IPC performance.This thesis focuses on combining the fault tolerant control (FTC) techniques with load reduction strategies by a more intelligent pitch control system (i.e. collective pitch control and IPC) for offshore wind turbines in a system level to reduce the operation & maintenance costs and improve the system reliability. The scenario of load mitigation is analogous to the FTC problem because the action of rotor/tower bending can be considered as a fault effect. The essential concept is to attempt to account for all the "fault effects" in the rotor and tower systems which can weaken the effect of bending moment reduction through the use of IPC.Motivated by the above, this thesis focuses on four aspects to fill the gap of the combination between FTC and IPC schemes. Firstly, a preview control system using model predictive control with future wind speed is proposed, which could be a possible alternative to using LiDAR technology when using preview control for load reduction. Secondly, a multivariable IPC controller for both blade and tower load mitigation considering the inherent couplings is investigated. Thirdly, appropriate control-based fault monitoring strategies including fault detection and fault estimation FE-based FTC scheme are proposed for several different pitch actuator/sensor faults. Furthermore, the combined analysis of an FE-based FTC strategy with the IPC system at a system level is provided and the robustness of the proposed strategy is verified

Optimal control of wind turbines for distributed power generation

textWind energy represents one of the major renewable energy sources that can meet future energy demands to sustain our lifestyle. During the last few decades, the installation of wind turbines for power generation has grown rapidly worldwide. Besides utility scale wind farms, distributed wind energy systems contributes to the rise in wind energy penetration. However, the expansion of distributed wind energy systems is faced by major challenges such as the system’s reliability in addition to the environmental impacts. This work is intended to explore various control algorithms to enable the distributed wind energy systems to face the aforementioned challenges. First of all, a stall regulated fixed speed wind turbine augmented with a variable ratio gearbox has been proven to enhance the wind energy capture at a relatively low cost, and considered as an attractive design for small wind energy systems. However, the high reliability advantage of traditional fixed-speed wind turbines can be affected by the integration of the variable ratio gearbox. A portion of this work is intended to develop a control algorithm that extends the variable ratio gearbox service life, thus improves overall system reliability and reduces the expected operational cost. Secondly, a pitch regulated variable speed wind turbines dominates the wind energy industry as it represents a balance between cost and flexibility of operation. They can be used for midsized wind power generation. Optimizing its wind energy capture while maintain high system reliability has been the one of the main focuses of many researchers. Another portion of this work introduces a model predictive control framework that enhances the reliability of pitch regulated variable speed wind turbines, thus improves their operational cost. Finally, one of the major environmental challenges facing the continuous growth of wind energy industry is the noise emitted from wind turbines. The severity of the noise emission problem is more significant for small and medium sized wind turbines installed in the vicinity of residential areas for distributed power generation. Consequently, the last portion of this work is intended to investigate the potential of wind turbine control design to reduce noise emission in different operating conditions with minimal impact on power generationMechanical Engineerin

A novel switched model predictive control of wind turbines using artificial neural network-Markov chains prediction with load mitigation

The existing model predictive control algorithm based on continuous control using quadratic programming is currently one of the most used modern control strategies applied to wind turbines. However, heavy computational time involved and complexity in implementation are still obstructions in existing model predictive control algorithm. Owing to this, a new switched model predictive control technique is developed for the control of wind turbines with the ability to reduce complexity while maintaining better efficiency. The proposed technique combines model predictive control operating on finite control set and artificial intelligence with reinforcement techniques (Markov Chains, MC) to design a new effective control law which allows to achieve the control objectives in different wind speed zones with minimization of computational complexity. The proposed method is compared with the existing model predictive control algorithm, and it has been found that the proposed algorithm is better in terms of computational time, load mitigation, and dynamic response. The proposed research is a forward step towards refining modern control techniques to achieve optimization in nonlinear process control using novel hybrid structures based on conventional control laws and artificial intelligence.© 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)fi=vertaisarvioitu|en=peerReviewed

A survey of differential flatness-based control applied to renewable energy sources

Conference ProceedingsThis paper presents an overview of various methods used to minimize the fluctuating impacts of power generated from renewable energy sources. Several sources are considered in the study (biomass, wind, solar, hydro and geothermal). Different control methods applied to their control are cited, alongside some previous applications. Hence, it further elaborates on the adoptive control principles, of which includes; Load ballast control, dummy load control, proportional integral and derivative (PID) control, proportional integral (PI) control, pulse-width modulation (PWM) control, buck converter control, boost converter control, pitch angle control, valve control, the rate of river flow at turbine, bidirectional diffuser-augmented control and differential flatnessbased controller. These control operations in renewable energy power generation are mainly based on a steady-state linear control approach. However, the flatness based control principle has the ability to resolve the complex control problem of renewable energy systems while exploiting their linear properties. Using their flatness properties, feedback control is easily achieved which allows for optimal/steady output of the system components. This review paper highlights the benefits that range from better control techniques for renewable energy systems to established robust grid (or standalone generations) connections that can bring immense benefits to their operation and maintenance costs

Provision of ancillary services by renewable hybrid generation in low frequency AC systems to the grid

Wind energy high penetration levels in power systems lead to continuous power imbalance due to the intermittent nature of wind power. This paper proposes and investigates different methods to enable a hybrid generation system to provide frequency support to the grid. The hybrid generation is 100% renewable and composed of a wind farm and hydropower plant (HPP) of comparable generation capacities, and they are interconnected through a Low Frequency AC system (LFAC). The grid–tie is composed of a Voltage-Source Converter based High-Voltage, Direct Current (VSC-HVDC) junction that acts as frequency changer to maintain the grid nominal frequency. The HPP provides two types of ancillary services: wind power smoothing and frequency drops mitigation to avoid the use of thermal generation and battery energy storage. The paper offers different control methods to provide the two AS with improved coordination between the different controls in the hybrid generation system and complying with the common requirements of Grid Codes. The results obtained show that the frequency at the LFAC can tolerate mild drops to provide frequency support to the grid. The controllers’ parameters have a clear impact on the frequency response at both systems. Simulation environment is MATLAB and Simulink

Automatic Flight Control Systems

The history of flight control is inseparably linked to the history of aviation itself. Since the early days, the concept of automatic flight control systems has evolved from mechanical control systems to highly advanced automatic fly-by-wire flight control systems which can be found nowadays in military jets and civil airliners. Even today, many research efforts are made for the further development of these flight control systems in various aspects. Recent new developments in this field focus on a wealth of different aspects. This book focuses on a selection of key research areas, such as inertial navigation, control of unmanned aircraft and helicopters, trajectory control of an unmanned space re-entry vehicle, aeroservoelastic control, adaptive flight control, and fault tolerant flight control. This book consists of two major sections. The first section focuses on a literature review and some recent theoretical developments in flight control systems. The second section discusses some concepts of adaptive and fault-tolerant flight control systems. Each technique discussed in this book is illustrated by a relevant example