condition monitoring solutions for wind turbines

7/29/2019 Condition Monitoring Solutions for Wind Turbines

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Condition monitoring solutions

for the wind turbines

Presented at CMVA 2009

Vancouver


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Objectives

Explain the wind turbine problems , and theirfailure modes

Explain how QPS would solve theseproblems

Explain the technology behind our solutions

Explain ~ Fiber Grating technology~ Fiber Grating technology

~ VibroFibre~ VibroFibre TMTM

~ Two Wave Mixing~ Two Wave Mixing


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QPS Expertise and history Invented The Phase Mask Technology

Pioneered in Fiber Gratings technology ,

product and process development for the

telecom industry , first volume supplier

Providing OEM products and solutions usingfiber Bragg gratings technology

In 2006 Peter Kung invented and patented a

Fibre Bragg Grating structure VibroFibre

to measure vibration


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A Wind turbine with a broken blade


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Early problems, things are certainly getting better now


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Failure Modes

Wind turbine are rated to last 20 years

Problems start to appear in the first 5 years in

gear box and drive train bearings

After 10 years , the supporting structure and the

blade would age and accidents might start to

occur if the wind becomes stronger than

expected , extreme temperature cycles , in factthey are working in a very hostile environment


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Problems with the Gear Box

Gearboxes located inside the casings perched on top of

the tower often have short operating lives. They areknown to fail within only five years.

Problem might not be caused

by poor quality componentsand poor maintenance:

Rapid changes in wind speed

and direction have passed on

extraordinary stresses onto

the gear box


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Other Important problems

Fractures form along the rotors, fractures in thefoundation

We have proof that strong vibration is facilitated

by looseness inside the generator, they cause

the insulating layer to rub and deteriorate,

resulting in windings shorts, arcing , and partial

discharge . High arcing current would cause

local heating and eventually , fire can occur likethe previous slide.


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We are now helping customers to avoid this


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Other important issues

Continuous Non-destructive testing of theinstalled blades providing long term trending ,along with info on structural health anddiagnostics.

Use Wireless to transfer the test data fromeach wind turbine, a mesh network links allturbines to a central and distributed database


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Hostile environment add to our risks

Strong wind can generate excess forceson the gear box, the blades and the tower

Corrosion can gradually affect the strength

of the tower

Excessive wind speed can cause torsionalstrain and distort the blades , previous

cases showed the blade could even bendand hit the tower , causing it to collapse


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Failure mechanism with the blades

The blades are made of fiber glass impregnated withresin . They have good mechanical strength and have

reduced weight . However, they are brittle: resin ages

and layers peel , sudden impacts (like birds, bats and

lightning ) can cause delamination and fiber breaks

It would be hard to visually inspect the blades during

operation (even if you stop it from turning), it is hard to

physically observe the process of delamination and fiber

breakage underneath the surface. Ultrasound would betoo time- consuming and expensive


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Fiber breakage

Localized Fiber strands can get broken duringsmall impacts, causing the shape of the blade to

change, further weakening the structure so that

it cannot cope with sudden changes in wind

speed and direction.

Why not provide real time feedback of these

rapid changes so that pitch control and YAW

control can react and ease the stress


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Technology behind QPS solution

Advanced VibroFibreTM technology

Each sensor is a fiber laser

Up to 30 sensors can be on the same fiberand each sensor is self identifying

Real time response : DC to 300Khz

Support both dynamic strain measurementimpact events and vibration measurement

One system (with up to 16 channels) cansupport 480 sensors


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Key BenefitsKey Benefits

FBG is small in size and light in weightFBG is small in size and light in weight

Long operating life, guaranteed 25 yearsLong operating life, guaranteed 25 years Can connect sensors in series making it low costCan connect sensors in series making it low cost

and Ideal for remote and distributed sensingand Ideal for remote and distributed sensing

FBG sensor is passive, draws 0 powerFBG sensor is passive, draws 0 power Immune to RFI and EMIImmune to RFI and EMI

Work well in hostile environment, like frequentWork well in hostile environment, like frequent

temperature cycles, corrosive environmenttemperature cycles, corrosive environment


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How these would be installed


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Installation is done by rolling out

the tape on an handle


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NDT automation, a Key concept

Two Wave Mixing (TWM) Use surface waves to do the detective work for

defects in the composites

Two very different frequencies can be coupledonto each blade from its base with a small

shaker, with 1X and 10X mixed frequencies ,

they will propagate along the blade and arrive at

the VibroFibre sensor at the tip or along astring of sensors mounted on the blade


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What is this TWM method?What is this TWM method?

It is a hybrid method, a small shaker will besending two vastly different frequencies , A andB . VibroFibre is used to detect the output( for example 400Hz and 8KHz) because it is lowloss despite long length

If there is no defects, we will detect the sametwo distinct frequencies , no mixing

If there are defects, we will observe mixing of A

and B plus harmonics on the lower frequency ,sensitivity is 100 times that of ultrasound


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Normal effect of acousticsNormal effect of acoustics


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Theory of TWMTheory of TWM


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Benefits-early warning of defectBenefits-early warning of defect

and you decide when to reactand you decide when to react


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Two wave Mixing shaker waveformTwo wave Mixing shaker waveform


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Detecting delamination and fiber breaks

By scanning the frequencies, you canidentify the resonant frequency of eachtype of defect.

A defect signature library based on thecharacteristics of blade design and thematerial can be created. QPS can workwith each Manufacturer to develop a

Defect Library becoming IntellectualProperty specific to them.

TWM f d d b d


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TWM response from good and badTWM response from good and bad

fiber glass coupons in a feasibility testfiber glass coupons in a feasibility test

Monitoring the blades with Advanced VibroFibre array to do


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Monitoring the blades with Advanced VibroFibre array to do

dynamic strain ,vibration , impacts and continuous TWM


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The same architecture can

monitor the tower and its

foundation


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Many vibration sensors can be installed at low cost


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Our objective is to make a most cost-

effective solution on a single system

For more informationFor more information

Please contact Peter KungPlease contact Peter Kung

Telephone 1-514-697-4728Telephone 1-514-697-4728 Cell phone 1-514-578-6766Cell phone 1-514-578-6766

EmailEmail [email protected]@qpscom.com

SKYPE: peter.kung.qpsSKYPE: peter.kung.qps


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condition monitoring solutions for wind turbines

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