o&m –part iii - japan | ul · 3/7/2015 · the maintenance concept is generally divided into...

SITE ASSESSMENT . WIND TURBINE ASSESSMENT . GRID INTEGRATION . DUE DILIGENCE . KNOWLEDGE . CONSULTANCY

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O&M – Part IIIMaintenance Optimisation

Michaël Drexler ‐ Tokyo, 03/03/2015


Agenda

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1. Maintenance strategiesI. Preventive MaintenanceII. Corrective MaintenanceIII. Maintenance Optimisation

2. Condition Monitoring SystemI. Benefits of a CMSII. Insurance and CMSIII. Condition Monitoring for drive train

3. Wind Turbine AssessmentI. Turbine inspectionII. Component inspection

4. Wind Farm Performance AnalysisI. Data AnalysisII. On site measurements


The term maintenance is referred to a combination of all technical, administrative andmanagerial actions during the life cycle of an item intended to retain it in, or restore itto, a state in which it can perform the required function.

The maintenance concept is generally divided into preventive maintenance (PM) andcorrective maintenance (CM).

An appropriate maintenance strategy will effectively reduce the total LCC (Life CycleCost) of wind turbines and maximise the ROI (Return of investment) in wind farms.

1. Maintenance strategies

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Maintenance

PreventiveMaintenance

Condition Based

Maintenance

ScheduledMaintenance

Corrective Maintenance


I. Preventive Maintenance

The Preventive Maintenance is carried out at predetermined intervals to postponefailures or to prevent failures from occurring.There are two different types of preventive maintenance:

• Scheduled maintenance,• Condition Based Maintenance.


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II. Corrective Maintenance

The Corrective Maintenance is carried out after a failure occurred and is intended torestore an item to a state in which it can perform its required functions.


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III. Maintenance Optimisation

The main purpose of maintenance optimisation is to determine the most cost‐effectivemaintenance strategy. This strategy should provide the best possible balance betweenpreventive and corrective maintenance.


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III. Maintenance Optimisation – Reliability Centered Maintenance

The Reliability Centered Maintenance (RCM) gives a systematic method to balancebetween preventive maintenance and corrective maintenance.

RCM method is a structured approach that focuses on reliability aspects whendetermining maintenance plans.

RCM is characterised by:• Maintaining system function• Identifying failure modes• Prioritising functions• Choosing efficient maintenance measure


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Condition Based Maintenance is only possible with appropriate procedures formeasuring the condition of the components in the system and by using a ConditionMonitoring System (CMS).

CMS comprise combinations of sensors and signal processing equipment that providecontinuous indications of component condition based on techniques including:• Vibration analysis• Acoustics• Lubricant analysis• Electrical effects• Others…

Monitoring may be on‐line (instantaneous) or off‐line (data collected at regular timeintervals).

2. Condition Monitoring Systems

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I. Benefits of a CMS

The implementation of a CMS will lead to some O&M benefits:

The primary objective is to detect behavioural changes while components areoperational and maintenance tasks can be planned in time to prevent damage orfailure of components.


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Characteristics Advantages Benefits

Early warning Avoid breakdownsBetter planning of maintenance

Avoid repair costsMinimize downtime

Identification of problem

Right service at the right timeMinimizing unnecessary replacementsProblems resolved before the time of guarantee expires

Prolonged lifetimeLowered maintenance costsQuality controlled operations during time of guarantee

Continuous monitoring Constant information that the wind power system is working

SecurityLess stress


II. Insurance and CMS

The leading insurance companies within wind power industry have createdrequirements for Condition Monitoring Systems on the complete drive train.

The different monitoring systems need to be tested and certified to fulfil theserequirements.

CMS concerns mainly the drive train components as they are based on rotationalcomponents which generate a typical vibration signature.


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III. Condition monitoring for drive train

A wide range of condition monitoring techniques can be used to assess the bearingsand gears conditions.


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Component Bearings GearsVibration analysis X XAcoustic emission X XDebris analysis X XLubricant analysis X XPressure monitoring ‐ XTemperature monitoring X XThermal imaging X XStress/Strain analysis ‐ XPerformance monitoring ‐ X


III. Condition monitoring for drive train

The key observables for wear and failure in gearboxes are:


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Increasing vibration Oil analysis Temperature measurement


III. Condition monitoring for drive train – Vibration analysis

Vibration analysis is the most popular technology for measuring thecondition of rotating equipment.

Different sensors are required for different frequencies:• Position transducers Low‐frequency range• Velocity sensorsMiddle frequency range• Accelerometers High frequency range• Spectral emitted energy sensors Very high frequency range

For WT this type of technology is mainly applicable for monitoring thebearings and gears of the gearbox, bearings of the generator and themain bearing.


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III. Condition monitoring for drive train – Vibration analysis

These techniques have proven to be very reliable and accurate in detecting abnormalmachine behaviour.

The monitoring is often executed by specialized suppliers which requires particularknowledge for signal analysis and diagnostics.

The costs are compensated by reduction of production losses.


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III. Condition monitoring for drive train – Lubricant analysis

Lubricant monitoring ensures safeguarding:

• The oil/grease quality• The components integrity

In case of excessive filter pollution, oil/grease contamination or change in componentproperties, characterization of particles can provide early warnings of components withexcessive wear.

Such approaches are particularly effective and cost‐effective in avoiding catastrophicfailures.


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III. Condition monitoring for drive train – Lubricant analysis

In applications where failure modes develop rapidly like a gearbox, an online real‐timeoil monitoring may be desirable.

The technology used to achieve an on line monitoring are based on:• Electromagnetic sensors (particle counter)• Flow or pressure sensors (filtration system)• Optical debris sensors (cleanliness assessment)


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Assessment of the current technical state of the Wind Turbine and their components toensure a safe and efficient operation.

3. Wind Turbine Assessment

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I. Turbine Inspection

Get a substantial view on the conditions of the Wind Turbine and Substation• Check consistency of the turbine documentation to the manufacturer’srecommendations

• Visual inspection (tower, foundation, mechanical and electrical components, blades)• Verification of the safety devices and the condition of functional tests (emergencyswitches, over speed, vibrations sensors)


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II. Component Inspection

Get a detailed status on the conditions of the Wind Turbine components• Technical audit• SCADA data analysis• Detailed inspection (NdT)

Focusing on main components:• Rotor Blades• Main bearing• Gearbox• Generator• Tower


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Understanding the performance of an operating wind farm is important to assess thefinancial performance of the project.

Different techniques are based on the data parameters recorded by the SCADA(Supervisory Control and Data Acquisition) systems, and focus on:• Availability (technical or energetic)• Power curve performance• DowntimesIn addition for certain issues, physical diagnosis on site may be required

Such analysis does require commitment, time and the use of sophisticated softwaretools combined with the knowledge of experience engineers.

High energy yield benefits can be considered through a wind farm performanceanalysis.

4. Wind Farm Performance Analysis

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I. Data analysis

SCADA data analysis is based on 10‐minute SCADA data and error logs. The analysisfocusing on :• Wind turbines power curves,• Production losses (energetic availability),


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I. Data analysis

The error code analysis enables to:• Detect the main causes of downtime• Detect possible malfunctioning of components (define further investigation on site)• Adjust maintenance if needed

2‐level approach :• Differentiation Turbine• Event types


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II. Physical diagnosis & on site measurement

Deeper and more accurate investigations in order to fix the problem and reach optimalperformance could conduct.

Major issues have an origin in wind turbine sub‐system adjustments:• Yaw : alignment of the rotor axis with the mean wind direction

• Reduce the dynamic loads and vibration level• Optimize the extracting energy from the wind

• Blade angles : adjustment of the 3 blades and the overall pitch angles for all blades• Reduce the dynamic loads and vibration level• Reduce production losses due to aerodynamic imbalance

• Rotor : Imbalance (mass and location)• Reduce the dynamic loads and vibration level• Reduce production losses due to mass imbalance


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o&m –part iii - japan | ul · 3/7/2015 · the maintenance concept is generally divided into...

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