Cyclic pitch control for the reduction of ultimate loads on wind turbines

Bottasso, Carlo L.; Croce, Alessandro; Riboldi, C. E. D.; Salvetti, Mauro

doi:10.1088/1742-6596/524/1/012063

Cited by 23 publications

(27 citation statements)

References 8 publications

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“…The actuator duty cycle (ADC) of the pitch system increases by 4.6% to 60 141 hours when IPC is used. The increase is relatively small compared with that in other literature sources . Moreover, the number of cycles with relatively small oscillation amplitudes (0.05‐1.05°) decreases when IPC is used.…”

Section: Resultsmentioning

confidence: 65%

“…Publications on the design of IPC often draw attention to the fact that the pitch drive exhibits a higher relative activity . The measurand for this is called the “actuator duty cycle (ADC)” and is the sum of all pitch movements.…”

Section: Reference Turbine Simulation and Data Analysismentioning

confidence: 99%

“…In addition to the individual blade root loads, it is possible to minimize certain rotor moments . Depending on the design of the controllers, which also depends on the site conditions, IPC can be used to reduce fatigue loads and extreme loads . When loads that are the drivers for the design of structures are reduced, these structures can be designed to be lighter and lower cost, thus reducing the capital costs of the wind turbine.…”

Section: Introductionmentioning

confidence: 99%

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Effect of load reduction mechanisms on loads and blade bearing movements of wind turbines

et al. 2019

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The power control of wind turbines is usually realized via a change in the pitch angle of the rotor blades. Pitching facilitates the exact control of the turbines and the reliable deceleration of the rotor when required. Pitch movements can moreover be used for load control. One of these methods is called individual pitch control (IPC). IPC controls the blades individually and brings about a significant reduction in the fatigue loads and extreme loads placed on the structural components, while at the same time reducing the yield of the turbine only slightly. The lower loads reduce material costs, and thus, the cost of energy (CoE) is reduced, despite the slight reduction in yield. The method is nevertheless not used everywhere since the additional movement cycles put the rotor blade bearings in particular under stress. Special attention must be paid to small amplitude oscillating movements, which carry a high risk of inducing surface damage in the rolling contacts of the blade bearings. This paper uses a cycle analysis of the IWT7.5-164 reference turbine to illustrate the differences in the movement patterns of wind turbine blade bearings with and without IPC. Moreover, model calculations with single contacts are used to show which of the movement patterns carries a risk of inducing surface damage. The use of IPC leads to the expected load reduction at the blade root. In current literature, IPC is usually assumed to have a negative influence on the life expectancy of blade bearings, but the findings of this study contradict this. The summed blade bearing movement is increased, although the number of very small pitch angles occurring is reduced. This reduction reduces the risk of wear in the blade bearings.

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Section: Resultsmentioning

confidence: 65%

Section: Reference Turbine Simulation and Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of load reduction mechanisms on loads and blade bearing movements of wind turbines

et al. 2019

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“…far from ideal constant wind conditions (Bottasso et al, 2014). For this reason, it makes sense to check the effect of the characteristic ranges R r and R o mainly in turbulent wind conditions and on J t , to determine whether this technological solution improves the performance of individual pitch control in more realistic conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Control tuning is the result of a trade-off analysis and is usually carried out by means of a time-consuming manual procedure. Bottasso et al (2014) restrict the use of individual pitch control to a limited range of wind speeds, selected to maximize the control effectiveness while minimizing actuator use. Yet also in that case, the selection of the activation range is completed by a manual trial and error procedure.…”

Section: Introductionmentioning

confidence: 99%

On the optimal tuning of individual pitch control for horizontal-axis wind turbines

Riboldi

2016

Wind Engineering

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Individual pitch control has proved capable of reducing loads on the blades and shaft of a horizontal-axis wind turbine, at the price of a potentially substantial increase in actuator activity. With accurate tuning of the control parameters, the overall performance can be satisfactorily balanced, but a manual tuning procedure often proves unbearably costly and the solution found may be far from optimal. This study tries to explore the feasibility of an optimal approach to the problem of tuning of individual pitch control, by mapping reasonable cost functions with respect to some parameters of interest in control design. The analysis is carried out by considering a possible individual pitch control implementation, tested in a virtual environment on a realistic testbed. The merit functions are also analyzed visually, in order to easily understand the effects of the various design parameters on the positions and quality of the respective optima. In a later stage, results of complete optimization runs are presented, and the approach is critically discussed

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Individual pitch control for 2‐bladed wind turbines via multiblade multilag transformation

Riboldi

Cacciola

2017

Wind Energy

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Two-bladed wind turbines have regained the attention of the community thanks to the advantages in manufacturing cost provided by the lower number of blades and the ease of implementation of effective passive systems for load reduction (ie, teetering pin). Considering both teetering and nonteetering architectures, the dynamics of 2-bladed turbines is different from that of 3-bladed machines especially in terms of how multiples of the rotor frequencies in blade signals are translated on the fixed system. Such characteristics have hampered the adoption of active control laws for load mitigation based on individual pitch control, extensively studied for 3-bladed turbines. A basic element for control development allowing to capture the essence of the relationship between signals on the blades and the fixed system on 2-bladed turbines-represented by the Coleman transformation for 3-bladed turbines-has not been identified yet. The present paper tries to fill the gap, presenting an extended transformation-called multiblade multilag-applicable to turbines with an arbitrary number of blades, providing a systematic way to link rotor signals to fixed system signals, thus allowing the application of control algorithms for individual pitch control developed for 3-bladed turbines to the 2-bladed case. The paper addresses the problem first at a theoretical level, and subsequently providing applicative results from simulations on virtual models of teetering and nonteetering 2-bladed turbines. The proposed transformation algorithm and control laws allow to effectively reduce some relevant loads and motions respectively in the nonteetering and teetering scenarios, through a cyclic pitch input

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Cyclic pitch control for the reduction of ultimate loads on wind turbines

Cited by 23 publications

References 8 publications

Effect of load reduction mechanisms on loads and blade bearing movements of wind turbines

Effect of load reduction mechanisms on loads and blade bearing movements of wind turbines

On the optimal tuning of individual pitch control for horizontal-axis wind turbines

Individual pitch control for 2‐bladed wind turbines via multiblade multilag transformation

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