DK173029B1

DK173029B1 - Method and apparatus for dampening of vibrations in rotor blades of windmills

Info

Publication number: DK173029B1
Application number: DK199700380A
Authority: DK
Inventors: Niels Emil Bjerre Hansen
Original assignee: Dancontrol Engineering As
Priority date: 1997-04-04
Filing date: 1997-04-04
Publication date: 1999-11-22
Also published as: DK38097A

Description

DK 173029 B1DK 173029 B1

FREMGANGSMÅDE OG APPARAT TIL DÆMPNING AF SVINGNINGER I ROTORBLADE PÅ VINDMØLLERMETHOD AND APPARATUS FOR ATTACHING Vibrations in Wind Turbine Rotor Blades

Denne opfindelse omhandler en fremgangsmåde og et apparat til overvågning af 5 vibrationsfænomener i en vindmølles vinger og til sikring imod skadelige følger heraf ved indgreb overfor fænomenet.This invention relates to a method and apparatus for monitoring phenomena of vibration in the blades of a wind turbine and for protecting against its deleterious effects by interference with the phenomenon.

Det er efterhånden erkendt, at visse meget udbredte vingetyper under visse omstændigheder er tilbøjelige til under drift at udvise kantvise vibrationer med en 10 amplitude, som i løbet af nogen tid vil forårsage uoprettelige skader på vingerne, hvis fænomenet ikke bringes til ophør. Udover de betragtelige økonomiske følger heraf indebærer dette en risiko for havari samt tilbageholdelse eller endda inddragelse af en vindmølles typegodkendelse.It is gradually recognized that in certain circumstances, certain widely used blade types tend to exhibit angular vibrations of an amplitude which, over time, will cause irreparable damage to the wings if the phenomenon is not brought to an end. In addition to the considerable financial consequences thereof, this entails a risk of failure as well as withholding or even withdrawal of a wind turbine's type approval.

15 Eftersom fænomenet knapt forstås af vingefabrikanterne, må det forudses, at selv nyproducerede vinger også i umiddelbar fremtid vil kunne udvise denne opførsel.15 Since the phenomenon is hardly understood by the blade manufacturers, it must be foreseen that even newly produced blades will be able to exhibit this behavior in the immediate future.

Det er derfor af største betydning for vindmøllebranchen som helhed, at der kan anvises en pålidelig og driftssikker fremgangsmåde og et apparat til detektion af og 20 indgreb overfor fænomenet.It is therefore of the utmost importance for the wind turbine industry as a whole that a reliable and reliable method and apparatus for detecting and intervening against the phenomenon can be provided.

Fordi fænomenet udvises af forskellige vingetyper, og fordi disse anvendes af flere forskellige vindmøllefabrikanter, vil vibrationsfænomenet variere fra én maskintype til en anden, men kan dog i det store og hele forventes at være karakteristisk for hver 25 maskintype.Because the phenomenon is exhibited by different blade types and because they are used by several different wind turbine manufacturers, the vibration phenomenon will vary from one machine type to another, but can be expected to be characteristic of every 25 machine types.

Det ifølge opfindelsen skitserede apparat er egnet til indbygning også i allerede opstillede vindmøller, og udviser en fleksibilitet med hensyn til måling og detektion, der muliggør dets anvendelse på alle kombinationer af maskin- og vingetyper.The apparatus outlined in accordance with the invention is suitable for incorporation even in already-established wind turbines, and exhibits a measurement and detection flexibility that allows its use on all combinations of machine and blade types.

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Vindmøller er almindeligvis forsynet med en mekanisme til detektion af voldsomme vibrationer, for eksempel ved grov ubalance i rotoren, hvis denne helt eller delvist skulle tabe en vinge. Denne mekanisme kan ikke detektere kantvise svingninger i vingerne, førend de kantvise svingninger har beskadiget vingerne.Wind turbines are generally provided with a mechanism for detecting violent vibrations, for example, by gross imbalance in the rotor, if it should drop a blade completely or partially. This mechanism cannot detect angular oscillations in the blades until the oblique oscillations have damaged the blades.

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Andre foranstaltninger beror på indbygning af vibrationssensorer i selve vingerne, men dette princip kan ikke anvendes i allerede opstillede vindmøller uden urealistisk høje omkostninger til ombygning.Other measures are based on the incorporation of vibration sensors in the wings themselves, but this principle cannot be applied to already installed wind turbines without unrealistically high cost of conversion.

5 Atter andre foranstaltninger beror på vindmøllestyringens begrænsning af vindmøllens drift under bestemte meteorologiske forhold; men denne fremgangsmåde har vist sig upålidelig, dels fordi fænomenet ikke udelukkende styres af meteorologiske forhold, og dels fordi fremgangsmåden på visse lokaliteter vil give anledning til urimelige produktionstab, hvor de kritiske meteorologiske forhold er fremherskende.5 Still other measures depend on the wind turbine management's limitation of the wind turbine's operation under certain meteorological conditions; but this approach has proved unreliable, partly because the phenomenon is not solely governed by meteorological conditions, and partly because the approach at certain localities will give rise to unreasonable production losses, where the critical meteorological conditions prevail.

1010

Det er derfor formålet med den foreliggende opfindelse at angive en fremgangsmåde til at detektere kantvise svingninger i en vindmølles vinger, så der i rette tid kan gribes ind for at begrænse nævnte svingninger, samt at angive et apparat til brug ved udøvelse af fremgangsmåden.It is therefore the object of the present invention to provide a method for detecting angular oscillations in the blades of a wind turbine so that timely action can be taken to limit said oscillations, and to provide an apparatus for use in the practice of the method.

1515

Dette formål opnås ved en fremgangsmåde til overvågning af vibrationsfænomener i en vindmølles vinger og til sikring imod skadelige følger heraf ved indgreb overfor fænomenet, hvilken fremgangsmåde omfatter: 20 - tilvejebringe en vibrationssensor, - orientere vibrationssensorens i det plan, som udviser størst følsomhed overfor vingernes kantvise vibrationer, 25 - måle et vibrationssignal, - sammenligne vibrationssignalet med en forud fastsat grænseværdi, og - påvirke omdrejningstallet for vindmøllens rotor ved overskridelse af 30 grænseværdien.This object is achieved by a method for monitoring vibrational phenomena in the blades of a wind turbine and for preventing their detrimental effects by engagement with the phenomenon, which comprises: - providing a vibration sensor, - orienting the vibration sensor in the plane which exhibits the greatest sensitivity to the edge of the blades. vibrations, 25 - measuring a vibration signal, - comparing the vibration signal with a predetermined limit value, and - influencing the rotor speed of the wind turbine rotor by exceeding the 30 limit value.

Fremgangsmåden er ifølge opfindelsen særegen ved, at vibrationssensoren er anbragt i vindmøllens maskinhus så fjernt fra vindmøllens rotor som muligt.The method according to the invention is peculiar in that the vibration sensor is arranged in the wind turbine machine housing as far away from the wind turbine rotor as possible.

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Apparatet til brug ved udøvelse af fremgangsmåden ifølge krav 1 omfatter ifølge opfindelsen - en primær målekæde omfattende en vibrationssensor hvis følsomhedsakse er 5 orienteret i et plan, som ved den givne kombination af maskin- og vingetype har størst følsomhed overfor vingernes kantvise vibrationer, - en indretning med et justerbart båndpasfilter og en komparator til at sammenligne vibrationssignalet med en forud fastsat grænseværdi koblet til 10 vibrationssensorens udgang, og - et udgangsrelæ indskudt til at påvirke rotorens omdrejningstal ved overskridelse af grænseværdien.The apparatus for use in the method of claim 1, according to the invention, comprises - a primary measuring chain comprising a vibration sensor whose sensitivity axis is oriented in a plane which, with the given machine and blade type combination, has the greatest sensitivity to the angular vibrations of the wings, - a device with an adjustable bandpass filter and a comparator for comparing the vibration signal with a predetermined limit value coupled to the output of the vibration sensor, and - an output relay inserted to affect the rotor speed by exceeding the limit value.

15 Apparatet er ifølge opfindelsen særegen ved, at vibrationssensoren er anbragt i vindmøllens maskinhus så fjernt fra rotoren som muligt.According to the invention, the apparatus is peculiar in that the vibration sensor is arranged in the wind turbine machine housing as far from the rotor as possible.

De uselvstændige krav omhandler fordelagtige måder at gå frem på henholdsvis fordelagtige udførelsesformer for apparatet ifølge opfindelsen.The dependent claims relate to advantageous ways of advancing respectively advantageous embodiments of the apparatus according to the invention.

2020

Opfindelsen forklares nærmere i det følgende ved hjælp af den vedføjede tegning, der viser et lodret længdesnit gennem en vindmølle, som er udstyret med et apparat ifølge opfindelsen.The invention is explained in more detail below with the aid of the attached drawing showing a vertical longitudinal section through a wind turbine equipped with an apparatus according to the invention.

25 På tegningen er vist et lodret længdesnit gennem en vindmølle, der som helhed er angivet med henvisningstallet 1. Vindmøllen 1 har et rotomav 2 med vinger 3, der er anbragt på en langsomt gående aksel 4. Akslen 4 strækker sig ind i et gear 5, hvor rotorakslens 4 lave omdrejningstal sættes i vejret og via en hurtigtgående aksel 6 overføres til en generator 7. Akslen 4, gearet 5, akslen 6 og generatoren 7 er 30 omsluttet af et maskinhus 8, en såkaldt nacelleinddækning.25 The drawing shows a vertical longitudinal section through a wind turbine as a whole indicated by the reference numeral 1. The wind turbine 1 has a rotor hub 2 with wings 3 arranged on a slow-moving shaft 4. The shaft 4 extends into a gear 5 , in which the low rpm of the rotor shaft 4 is raised and transmitted via a fast-moving shaft 6 to a generator 7. The shaft 4, the gear 5, the shaft 6 and the generator 7 are enclosed by a machine housing 8, a so-called nacelle cover.

Der tilvejebringes en primær målekæde omfattende en vibrationssensor 9, der er anbragt i maskinhuset 8 så langt fra rotoren 2, 3 som muligt og med sensorens 9 følsomhedsakse orienteret i et plan, som ved den givne kombination af maskin- og 4 DK 173029 B1 vingetype har størst overførselsevne for den kantvise vibrationsfrekvens for vingerne 2.A primary measuring chain is provided comprising a vibration sensor 9 arranged in the machine housing 8 as far from the rotor 2, 3 as possible and with the sensitivity axis of the sensor 9 oriented in a plane which, by the given combination of machine and 4 wing type greatest transferability of the angular vibrational frequency of the wings 2.

Dette plan bestemmes enten ved vindmøllefabrikantens beregning eller empirisk for 5 hver kombination af maskin- og vingetype.This plan is determined either by the wind turbine manufacturer's calculation or empirically for each machine and blade type combination.

Signalet fra vibrationssensoren 9 overføres til en indretning 10, som har et båndpasfilter, der er justerbart. Båndpasfilteret justeres på en sådan måde, at indretningen 10 måler vibrationsniveauet i en omegn af den frekvens, der er ka-10 rakteristisk for vingernes 2 kantvise svingning i den aktuelle kombination af maskin-og vingetype.The signal from the vibration sensor 9 is transmitted to a device 10 which has a bandpass filter that is adjustable. The bandpass filter is adjusted in such a way that the device 10 measures the level of vibration in an area of the frequency characteristic of the angular oscillation of the blades 2 in the current combination of machine and blade type.

Den i indretningen 10 registrerede amplitude af vibrationssignalet sammenholdes i en komparator med en for den givne kombination af maskin- og vingetype karakteristisk 15 grænseværdi. Hvis vibrationssignalet overskrider den forud fastsatte grænseværdi, er indretningen 10 indrettet til at påvirke et udgangsrelæ, hvis kontaktsæt på allerede opstillede vindmøller kan indskydes i vindmøllens nødstopkredsløb, hvorved vindmøllen bringes til standsning, subsidiært på nykonstruerede vindmøller kan give besked til vindmøllens styresystem om midlertidigt at reducere rotoromdrejningstallet, 20 indtil vibrationsfænomenet ophører.The amplitude of the vibration signal recorded in the device 10 is compared in a comparator with a limit value characteristic for the given combination of machine and wing type. If the vibration signal exceeds the predetermined limit value, the device 10 is arranged to actuate an output relay whose contact kits on already-installed wind turbines can be inserted into the wind turbine's emergency stop circuit, whereby the wind turbine is stopped, or alternatively, on newly constructed wind turbines, the wind turbine can be switched on. rotor speed, 20 until the phenomenon of vibration ceases.

Hvorvidt indretningen 10 på nykonstruerede vindmøller skal virke med sit udgangsrelæ i vindmøllens nødstopkredsløb vil være et anliggende for vindmøllefabrikanten og godkendende myndigheder.Whether the device 10 on newly constructed wind turbines operates with its output relay in the wind turbine emergency stop circuit will be a concern for the wind turbine manufacturer and approval authorities.

2525

Apparatet er indrettet, så det valgfrit kan konfigureres til enten automatisk at genindkoble udgangsrelæet en stilbar tid efter, at vibrationsniveauet er faldet og forblevet under grænseværdien, eller at lade udgangsrelæet være afbrudt, indtil der foreligger en manuelt indtastet kvittering for fejlmeldingen via en signalindgang.The device is configured so that it can optionally be configured to either automatically re-enable the output relay for an adjustable time after the vibration level has dropped and remained below the limit value, or to leave the output relay off until a manually entered acknowledgment of the error message is via a signal input.

3030

Hvorvidt den ene eller den anden konfiguration skal anvendes vil være et anliggende for vindmøllefabrikanten og godkendende myndigheder.Whether one or the other configuration should be used will be a concern for the wind turbine manufacturer and approval authorities.

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Fortrinsvis forsynes apparatet også med en sekundær målekæde i form af en omdrejningssensor 11 enten ved den hurtigtgående generatoraksel 6 eller en omdrejningssensor 12 ved den langsomtgående rotoraksel 4.Preferably, the apparatus is also provided with a secondary measuring chain in the form of a rotation sensor 11 either at the fast-moving generator shaft 6 or a rotation sensor 12 at the slow-moving rotor shaft 4.

5 Den primære og den sekundære målekæde anvendes til gensidig integritetskontrol, så man kan fæste lid til et registreret fravær af kantvis vingevibration: a) Dersom omdrejningssensoren 11 eller 12 indikerer et omdrejningstal over en vis indstilbar værdi, skal indretningen 10 samtidig registrere relativ højfrekvent 10 vibration fra maskineriet - i modsat fald antages svigt af vibrationsmålekæden 9, 10, hvilket meldes på et statusrelæ.5 The primary and the secondary measuring chain are used for mutual integrity control, so as to detect a recorded absence of angular wing vibration: a) If the rotation sensor 11 or 12 indicates a rpm above a certain adjustable value, the device 10 must simultaneously detect relatively high frequency 10 vibration from the machinery - otherwise failure of the vibration measuring chain 9, 10 is assumed, which is reported on a status relay.

b) Dersom vibrationsmålekæden 9, 10 detekterer højfrekvent vibration over et vist indstilbart niveau hidrørende fra maskineriet, skal apparatet samtidig modtage et 15 tilsvarende signal fra omdrejningssensoren 11 eller 12 - i modsat fald antages svigt af den sekundærs målekæde, hvilket meldes på et statusrelæ.b) If the vibration measuring chain 9, 10 detects high frequency vibration above a certain adjustable level resulting from the machinery, the apparatus must simultaneously receive a corresponding signal from the rotation sensor 11 or 12 - otherwise failure of the secondary measuring chain is assumed, which is reported on a status relay.

I allerede opstillede opstillede vindmøller kan såvel udgangsrelæ som statusrelæ indskydes i vindmøllens nødstopkredsløb, hvorved vindmøllen også kan bringes til 20 standsning ved sensorfejl.In already installed wind turbines, both the output relay and the status relay can be inserted into the wind turbine's emergency stop circuit, whereby the wind turbine can also be brought to a standstill by sensor failure.

I nykonstruerede vindmøller kan sensorfejl eventuelt meldes til vindmøllens styresystem, som vil kunne foretage en kontrolleret standsning eller nedbremsning af vindmøllen til et lavere omdrejningstal.In newly constructed wind turbines, sensor faults may be reported to the wind turbine's control system, which will be able to control or slow down the wind turbine to a lower speed.

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Hvorvidt et sensorfejlrelæ skal indskydes i vindmøllens nødstopkredsløb vil være et anliggende for vindmøllefabrikanten og godkendende myndigheder.Whether a sensor fault relay should be inserted into the wind turbine emergency stop circuit will be a concern for the wind turbine manufacturer and approval authorities.

Med henvisningstallet 13 angives et hasngekabel til vindmøllens nødstopkredsløb.Reference numeral 13 indicates a catch cable for the wind turbine emergency stop circuit.

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Claims

A method for monitoring vibrational phenomena in the blades (2) of a wind turbine (1) and for preventing its detrimental consequences by engaging in the phenomenon, comprising: providing a vibration sensor (9), orienting the vibration sensor (9) in that plane, exhibiting the greatest sensitivity to the edge vibrations of the 10 wings (2), measuring a vibration signal, comparing the vibration signal to a predetermined limit value, and 15 influencing the speed of the wind turbine rotor (2) by exceeding the limit value, characterized in that the vibration sensor (9) is located in the engine housing (8) of the wind turbine (1) as far from the wind turbine rotor (2) as possible.

Method according to claim 1, characterized in that the overrun of the vibration signal 25 is transmitted to an output relay inserted in the wind turbine (1) which is adapted to actuate the emergency stop circuit for stopping the wind turbine (1).

Method according to claim 2, characterized in that the output relay is only reconnected after manual entry via a signal input.

Method according to claim 1, characterized in that the overrun value of the vibration signal is transmitted to the wind turbine control system, which is arranged to temporarily reduce the speed of the rotor (2) of the wind turbine (1). DK 173029 B1

Method according to claim 4, characterized in that the rotor (2) of the wind turbine (1) is switched on again when the amplitude of the vibration signal has decreased and has remained below the limit value for an adjustable period.

Apparatus for use in practicing the method of claim 1 for monitoring vibrational phenomena in the blades (2) of a wind turbine (1) and for protecting against its deleterious effects upon engagement with the phenomenon, comprising: a primary measuring chain comprising a vibration sensor (9) ) whose sensitivity axis is oriented in a plane which, with the given machine and blade type combination, has the greatest sensitivity to the angular vibrations of the blades (2), a device (10) with an adjustable bandpass fitter, and a comparator to compare the vibration signal with a predetermined vibration signal. a threshold value coupled to the output of the vibration sensor (9) and an output relay inserted to influence the speed of rotation of the rotor (2, 3), characterized in that the vibration sensor (9) is arranged in the engine housing (8) of the wind turbine (1). as far from the rotor (2, 3) as possible.

Apparatus according to claim 6, characterized in that the apparatus comprises an output relay whose contact set on already installed wind turbines is inserted into the wind turbine's emergency stop circuit (1) or on newly constructed wind turbines arranged to engage the wind turbine's control system. means that the rotor speed is reduced until the vibration phenomenon has ceased. 30

Apparatus according to claim 6 or 7, characterized in that the apparatus comprises a signal input for manually entering a start signal for canceling an error message.