US-12618393-B2 - Determination of oscillation frequencies of wind turbines and related methods

US12618393B2US 12618393 B2US12618393 B2US 12618393B2US-12618393-B2

Abstract

The present disclosure is related to methods for determining a frequency of an oscillation mode of a wind turbine, comprising: determining a motion of a first mass of a first tuned mass damper in the wind turbine and deriving the frequency of the oscillation mode of the wind turbine at least partially based on the determined motion of the first mass. The present disclosure further relates to methods for operating a wind turbine, and to wind turbines, particularly offshore wind turbines, comprising tuned mass dampers.

Inventors

Isaac Pineda Amo

Assignees

GENERAL ELECTRIC RENOVABLES ESPANA, S.L.

Dates

Publication Date: 20260505
Application Date: 20240305
Priority Date: 20230306

Claims (12)

1 . A method for determining an updated frequency of an oscillation mode of a wind turbine, the method comprising: during a power-production or idling mode of the wind turbine, determining a frequency of oscillation motion of a first mass of a first tuned mass damper in the wind turbine; deriving the updated frequency of the oscillation mode of the wind turbine in the power-production or idling mode at least partially based on changes to the frequency of oscillation motion of the first mass; and in a control system of the wind turbine, incorporating the updated frequency of the oscillation mode of the wind turbine into one or more control strategies so that the one or more control strategies are adjusted based on the updated frequency of the oscillation mode of the wind turbine.
2 . The method of claim 1 , wherein the oscillation mode of the wind turbine is a first normal mode.
3 . The method of claim 1 , further comprising determining a frequency of oscillation motion of a second mass of a second tuned mass damper in the wind turbine, and deriving the frequency of the oscillation mode of the wind turbine also based at least partially based on the frequency of oscillation motion of the second mass.
4 . The method of claim 3 , wherein the first mass and the second mass are configured to move in substantially perpendicular directions relative to each other.
5 . The method of claim 1 , wherein determining the frequency of oscillation motion of the first mass of the first tuned mass damper comprises deriving a speed of motion of the first mass by monitoring a position of the first mass with respect to the wind turbine as a function of time.
6 . The method of claim 5 , wherein monitoring the position of the first mass comprises detecting the first mass at a target location.
7 . The method of claim 1 , wherein adjusting the control strategy comprises changing a pitch control strategy to avoid resonance in the wind turbine.
8 . A method for operating a wind turbine, the method comprising; determining an updated frequency of an oscillation mode of the wind turbine during a power-production or idling mode of the wind turbine by: determining a frequency of oscillation motion of a first mass of a first tuned mass damper in the wind turbine; and deriving the updated frequency of the oscillation mode of the wind turbine in the power-production or idling mode at least partially based on the frequency of oscillation motion of the first mass; the method further comprising: changing an exclusion range of rotational speeds of a rotor of the wind turbine so as to be based on the updated frequency of the oscillation mode; and operating the wind turbine so that an operational time of the wind turbine in the exclusion range is reduced or avoided due to changing the exclusion range to be based on the updated frequency of the oscillation mode.
9 . The method of claim 8 , further comprising determining a new frequency of the oscillation mode based on the frequency of oscillation motion of the first mass after a period of operation of the wind turbine and adjusting the exclusion range based on the new frequency.
10 . The method of claim 9 , further comprising adjusting the first tuned mass damper based on the new frequency.
11 . The method of claim 9 , further comprising storing historical data relative to the frequency of the oscillation mode; and estimating a remaining life expectancy of the wind turbine at least partially based on the stored historical data.
12 . A wind turbine, comprising: a tuned mass damper having a first mass; a control system in communication with the tuned mass damper, the control system configured to carry out the method according to claim 1 .

Description

FIELD The present disclosure relates to methods and systems for estimating a frequency of an oscillation mode of a wind turbine. Further, the present disclosure relates to methods for operating a wind turbine. BACKGROUND Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. This rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly (“directly driven” or “gearless”) or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid. Wind turbines have evolved rapidly over the last decades with a clear trend of increasing size. The power generated by a wind turbine is proportional to the rotor swept area and, therefore to the square of the blade length. Thus, higher towers and longer blades have been used with the goal of extracting more energy from the wind, leading to a higher electricity production. The increase in size over the years has led to a substantial increase in the loads acting on wind turbine components, and has posed new challenges for a wide range of disciplines including mechanical, electrical, materials and civil engineering among others. With the increase in size of wind turbines, wind turbines have also become more slender. Although load control in wind turbines has always been important to avoid structural failure and/or early retirement of components due to fatigue, this is even more important in the more recent, very tall wind turbines, e.g. with a power rating of 8 MW or more, specifically 10 MW or more, or 14 MW or more. The likelihood of structural failure, e.g. due to fatigue, in wind turbine components, such as a tower structure of the wind turbine or a foundation of the wind turbine, is inter alia related to the magnitude and frequency of loads acting on the wind turbine and how these are transferred to the ground, either on land or on the seabed. To mitigate premature structural failure of wind turbine components, it is known to take into account certain eigenfrequencies of the wind turbine. If the wind turbine is subjected to loads at or close to the eigenfrequency, resonance may occur, leading to rapidly increasing and dangerous loads. It is therefore known to define operational exclusions zones e.g. ranges of rotational speed where vibration resonances could cause severe structural damage and which are therefore to be avoided or reduced to a minimum. The eigenfrequencies (and the corresponding exclusion zones) are generally calculated in the design phase of the wind turbine. But measuring oscillations using e.g. accelerometers and deriving eigenfrequencies therefore may also be carried out for example during a commissioning phase. The determination of eigenfrequencies in installed wind turbines is a complicated exercise, generally relying on significant computational resources and which is generally not performed during operation. Wind turbine sites may be located on land (“onshore”) but they may also be placed off the coast in the sea (“offshore”) to increase the energy production of the site and reduce environmental impact among others. Wind speeds at offshore locations are typically higher than on land. Further, wind speeds and wind direction offshore tend to be more stable, and therefore offshore sites may have higher and more consistent energy production than land sites. In relation with load control and the aforementioned eigenfrequencies, offshore wind turbines represent an additional challenge. For example, wind turbines with the same monopile or jacket and wind turbine structure may have different eigenfrequencies in an offshore wind farm, because the soil is generally softer than on land, and soil conditions are more variable throughout a wind farm. The depth of the seabed is not necessarily constant resulting in different monopile lengths. Moreover, it has been found that the eigenfrequencies of particularly offshore wind turbines, both floating wind turbines and wind turbines fixed at the seabed, may vary over their lifetime. Growth of algae, crustacea, barnacles, and other along the tower or pile structure, or floating structure has an effect on the eigenfrequencies as well. If the eigenfrequencies change, the predetermined methods of operation may lead to higher loads than expected. In order to avoid higher loads, increased operational exclusion zones may be defined, but this might lead to suboptimum operation and a corresponding reduction in Annual Energy Production (AEP). The present disclosure provides methods and systems to at least partially overcome some of the aforementioned drawbacks. SUMMARY In an aspect of the present disclosure, a method for determining a frequency of an oscillation mod