Vaisala lidar User Manual

Nacelle-mounted lidar:
New advances in Power Performance Testing, optimization, and financial outcomes in wind energy
As wind energy continues to evolve, so do the financial stakes in maximizing power output and profit.
Today, even a minor difference between estimated and actual energy output creates substantial financial impacts. While developers and operators expect to get the energy output promised by manufacturers, they can’t know if they are succeeding without accurate Power Performance Testing (PPT) data. They are also unable to identify and take corrective actions that can extend the life of the turbine and reduce annualized cost of energy.
Enter nacelle-mounted lidar. With its exceptional accuracy and range, economical design and small footprint, nacelle-mounted lidar is one of the most reliable and affordable ways to assess a turbine and enable IEC-compliant PPT. Recent advances in the lidar itself and the software that interprets its data are revolutionizing wind farm operations.
This eBook explains how nacelle-mounted lidar works, how it is changing PPT, and why it is such a powerful solution for today’s ever-growing wind turbines and farms.
$500,000
Revenue loss from a 1% decrease in annual production (100 two-megawatt turbines)1.
© Vaisala 2021
Contents
How does nacelle-mounted lidar work? 4
Power Performance Testing in detail 6
Leosphere, a Vaisala company's, Windcube suite 10
Case study: Offshore PPT 12
Further applications for nacelle-mounted lidar 13
© Vaisala 2021
How does nacelle-mounted lidar work?
Wind speed measurement and the Doppler effect
Lidar emits light pulses at a very high frequency, and these light pulses are reflected back by aerosols in the atmosphere. The Doppler effect allows the lidar to accurately compute the speed of those particles — and, thus, the speed of the wind carrying them through the atmosphere. Today, wind lidar is used for a wide range of applications in wind energy, aviation, and meteorology.
Notably, WindCube© Nacelle operates on a pulsed lidar principle, which provides several important advantages over other lidar types. Pulsed lidar maintains constant accuracy over the entire measurement range, and it offers the highest accuracy, data availability, and sample rates regardless of weather conditions.
Nacelle-mounted lidar has evolved substantially in recent years. For example, earlier generations of WindCube Nacelle (formerly called Wind Iris) measured up to 450 meters at 10 measurement distances. This was extremely useful, but today’s version covers a measurement range from 50 to 700 meters at 20 separate distances, dramatically increasing PPT quality and making it suitable for even the largest turbines likely to be deployed now or in the future.
WindCube Nacelle measures from 50 to 700 meters at 20 separate distances, dramatically increasing PPT quality and making it suitable for even the largest turbines likely to be deployed now or in the future.
© Vaisala 2021
The best technology for the job
Once a wind turbine is deployed, its operators depend on its performance to match manufacturer expectations. Underperformance can be extremely costly — and without good wind data, it can go unobserved for months or years.
Back when turbines were smaller, this was less of a problem. But now that the scale of wind turbines has increased so much, so has the scale of the financial losses when they aren’t operating at maximum capacity. Even slight underperformances are no longer acceptable.
Traditionally, the way to assess power performance was to use a met mast. But because of their costs and logistical challenges, many wind operators simply skipped using them. One reason why is that you need to have both the met mast and the turbine aligned with the wind direction — meaning that frequent changes in wind direction can invalidate the measurements. Another is that the costs and logistical constraints are often too high for such a short measurement period. Nacelle-mounted anemometers are cheaper to use, but they are not accurate enough for reliable PPT.
Nacelle-mounted lidar, on the other hand, is much quicker and easier to deploy, and it collects data much faster. It is always aligned with the wind turbine because it moves with it, and it is typically half the cost (or less) of using a met mast, particularly for taller and offshore wind turbines. Lidar also uses multiple laser beams to cover the whole rotor area, creating more representative wind data that accounts for shear values and other influences acting in three dimensions. (This data, while not mandatory, can now be included in PPT for improved accuracy and higher certainty following IEC rules.)
Expert groups from IEC and independent consultants are also preparing guidelines for using nacelle­mounted lidar in complex terrain for the next revision of IEC standards.
The bottom line is that nacelle-mounted lidar is here to stay. It is the best solution for PPT — both onshore and offshore — and its continual improvements are making wind farms more profitable, reliable, and efficient.
© Vaisala 2021
Power Performance Testing in detail
PPT is the most critical application for nacelle lidar, since it provides operators and other stakeholders the power curve data they need to verify the performance of a wind farm project. Enormous financial resources are at stake in any PPT project.
Critical factors in PPT include:
Ability to accurately verify turbine power performance
Comparison of actual power curves with warranted power curves
Reduced logistics for setting-up and operating the measurement system
Optimized OPEX
Rapid data completion
Presentation and analysis of power curve data in an IEC-compliant format
Ensuring measurement traceability
© Vaisala 2021
Power Performance Testing planning and key steps
Four steps to success
A correctly managed PPT campaign is broken down into four stages.
2. Verification
Check the quality of the
in the campaign
3. Operation
Install, operate, and
monitor throughout the
campaign duration
1. Design
Plan the campaign as much as
possible in advance
system for every device used
4. Analysis
Extract data and act on it
Step 1: Design
The first decision in campaign planning is choosing which turbine(s) to measure. Operators can typically help minimize the length of the PPT campaign by selecting the one with the biggest opening sector.
Process
Decide on the needed applications: contractual or operational PPT, checking production increases after turbine upgrades, yaw alignment and nacelle-transfer function verification, research and turbine prototyping. (One data set can be used for multiple applications.)
Select the wind turbine to test: Maximize open sector following various rules
Anticipate installation steps including OEM authorizations and network access
Key documents:
IEC - 61400-12-1
IEC - 61400-50-3 – CDV (available as draft, and expected to be released from mid 2021)
Lidar manufacturer installation and safety guidelines
Various precursor project report – EUDP procedure (established by DTU, Orsted, Siemens-Gamesa and Leosphere)
© Vaisala 2021
Step 2: Verification and calibration
Verification ensures performance of the lidar. Much of the verification process can be done in parallel with design, and usually takes about two months at a certification site.
Process
Leosphere certification and verification standards
Verification at Leosphere: Leosphere calibrates lidar units throughout the manufacturing process, then verifies it against a calibrated lidar of the same type.
Third-party calibration: This is a contractual step for PPT, conducted at an independent test site. The analyst uses this data to calculate the uncertainty on the power curve. Key documents for the verification process:
EUDP and UniTTe reports
IEC: IEC 61400-50-3 – CDV (expected to be published in 2021)
Leosphere products meet the latest and most rigorous international verification standards, including ISO9001. All WindCube products are compliant to the latest IEC standards (when applicable), and they are recognized and verified by the world’s leading independent certifying bodies, including DNV GL, DTU Wind Energy, UL, and Deutsche WindGuard.
DNV GL calibration site in Germany
© Vaisala 2021
Step 3: Operation
Operation is a busy and important phase. It requires training, foresight, and effective project management.
Process
Installation: Training is provided. Documentation includes checklist and health/safety precautions. Complete alignment on nacelle roof.
Time synchronization: Use either NTP or GPS. All sensors should be synchronized, or the offset should be reported.
Monitoring: Conduct daily or weekly checks on all related equipment and sensors along with any automatic alerts.
Data collection: Choose automatic, FTP, or manual. Regularly check if data set is completed (see step 4).
Measured wind speeds
Step 4: Analysis
After a few weeks of operation, there will be enough information in the dataset to extract and analyze. This can overlap the monitoring phase.
Synchronization: This is a crucial, sometimes difficult, step in preparing for data extraction. (WindCube Insights—Analytics includes a simple-to-use synchronization function).
Filtering: Isolate a time period when everything was working nominally and proper data was being returned.
Data completion: The IEC provides guidance that will help you determine whether your dataset is complete. Key indicators include:
180h of valid measurement
At least three measurements per bin (0.5m/s)
Range of wind speed according to turbine nominal power
Complete analyses according to IEC procedures.
PC, Cp, AEP
And associated uncertainty
Terrain assessment
Obstacles & topo
Power curve
© Vaisala 2021
WindCube Nacelle: The industry's most trusted and deployed nacelle-mounted lidar
WindCube Nacelle is one of the most accepted and widely deployed nacelle-mounted lidar systems in the world.
It is the only long range nacelle-mounted lidar that enables PPT on any wind turbine — onshore or offshore. Its accuracy and versatility have made Leosphere a contributing expert to industry guidelines and standards for PPT.
Key benefits
Enables quick, accurate, compliant PPT
Rapid data completion with continuous wind direction alignment Reliable contractual and operational PPT Based on industry best practices and upcoming IEC standards
Accurate data from 50 to 700 meters
Captures wind data simultaneously at 20 measurement distances Extremely high correlation with IEC met mast measurements Gives wind industry stakeholders the reliable data needed to make better decisions
WindCube Nacelle also provides a wide range of supporting data, including shear, veer, turbulence, and is ready for REWS (Rotor Equivalent Wind Speed)
Universal compatibility and ease of use
Compatible with all current and future turbine types Simple installation and system integration and configuration Outstanding reliability under even the most demanding conditions Permits a 3-year warranty period and limited maintenance
© Vaisala 2021
WindCube Insights — Analytics: Revolutionary software enabling IEC-compliant PPT
No other lidar provider offers a solution like it.
WindCube Insights — Analytics software completes the PPT process by analyzing, interpreting, and displaying the data obtained from WindCube Nacelle.
Operators can perform quick, simple, and transparent PPT with IEC-compliant filtering, AEP calculation, and uncertainties reporting. Simplifying data handling activities frees users to focus on the most essential performance analysis and optimization work.
Since PPT is a very strict process, this tool provides transparent validations and even lists which IEC standards are relevant while in use. It allows for the upload of WindCube Nacelle and SCADA data with a simplified data synchronization process, and provides a variety of standardized lidar and turbine data filters that are available and fully configurable to prepare the data set.
Key benefits
Easy-to-use, fully compliant, affordable PPT analytics
Eliminates time-consuming and expensive processes developed in-house Provides powerful performance calculations and data integrations
Adheres to accepted industry best practices
Backed by rigorous, transparent validations Proactively displays which IEC paragraph/standard it is referring to while in use
Improved data visibility and value for the whole wind farm
Gives users outstanding awareness of their systems Simple interface, efficient analyses, and easy report table exporting Enables data-driven decision-making and better-functioning wind farms
© Vaisala 2021
Case study: Offshore PPT
Siemens Gamesa Renewable Energy
Siemens Gamesa Renewable Energy, one of the world's largest wind turbine manufacturers, provides offshore and onshore wind services and is well-known as a renewable energy industry leader.
The company has been using nacelle-mounted lidar in place of met masts for several years because many of the limitations of using met masts are compounded offshore. Met masts offshore are prohibitively expensive and, between permitting and the building process itself, can take years to implement.
Siemens Gamesa has adopted nacelle-mounted lidar in offshore applications for several primary reasons:
Reduced cost
Wider measurement sector in most cases
Faster power curve calculations due to the wider measurement sector
Ability to collect both short-range (inside the induction zone) and long-range data simultaneously
WindCube Nacelle measures up to 700m to cover their largest offshore wind turbines
As an early adopter of nacelle-mounted lidar for offshore applications, Siemens Gamesa is leading its field and routinely proving the value of WindCube Nacelle.
© Vaisala 2021
Further applications for nacelle-mounted lidar
Although nacelle-mounted lidar’s primary purpose is PPT, it is a multi-use tool that creates impressive efficiencies and cost savings throughout a wind farm’s lifespan.
Any of these secondary applications can be compelling enough on their own to deploy nacelle-mounted lidar. They include:
Turbine yaw misalignment
Nacelle-mounted lidar allows
operators to identify and correct any
misalignment between the turbine
and wind direction — maximizing
performance and reducing structural
loads. Nacelle-mounted lidar is the
only proven technology for this cost-
saving assessment.
Research Project
Many agencies and companies rely
on highly detailed wind field data for
studies and product development. Nacelle-mounted lidar can provide
previously unavailable detail and
precision, leading to accelerated
innovation and new insights.
Nacelle transfer function
Nacelle transfer function, which
describes how the turbine and nacelle
structures influence wind speed, is
an important assessment to improve
turbine performance monitoring.
Nacelle-mounted lidar assesses this
accurately even after a wind campaign
is complete.
Lidar assisted control
Lidar-assisted control (LAC) allows for anticipatory
adjustments to blade and turbine alignment to
better handle incoming weather or storms. LAC can
substantially reduce turbine cost, reduce loads on
the turbine and nacelle, improve longevity, and
reduce risk. It can also increase energy capture and
lower the levelized cost of energy (LCOE). WindCube
Nacelle for Turbine Control is the ideal, custom-
made solution for this purpose. Learn more about it
at windcubelidar.com.
© Vaisala 2021
Why Leosphere, a Vaisala company?
We are modern innovators, scientists, and discoverers who enable our customers to harness the power of wind energy in new ways. We are driven by passion, relentless curiosity, and the desire to create a better world, as evidenced in our commitment to four guiding principles:
Trustworthy, superior metrology
Our solutions are backed by the best science and metrology, and validated by the most demanding testing and certifications in the industry. Our contributions make wind energy smarter.
Unrivaled thought leadership
Our years of experience, impressive global client roster, and plethora of industry breakthroughs demonstrate that we are the iconic gold standard in wind energy.
As a result, Leosphere, a Vaisala company, is the iconic and trusted gold standard in wind lidar. Our turnkey WindCube product suite offers innovative, reliable, and highly accurate solutions for thousands of customers across the globe. All of this has enabled us to be catalysts for change and ambassadors for wind energy, always advancing the field and those we serve.
Our innovation story, like the wind energy story, continues.
Innovative lidars from a one-stop shop
Customers know we have the right suite of solutions for their needs in wind energy — taking them ever higher by adding value at each step of the project lifecycle.
Easy, reliable global solution
We make our clients’ lives easier. Our easy to use, turnkey WindCube product suite enables customers to harness the power of wind energy efficiently and affordably.
windcubelidar.com
Ref. B211919EN-C ©Vaisala 2021
This material is subject to copyright protection, with all copyrights retained by Vaisala and its individual partners. All rights reserved. Any logos and/or product names are trademarks of Vaisala or its individual partners. The reproduction, transfer, distribution or storage of information contained in this ebook in any form without the prior written consent of Vaisala is strictly prohibited. All specifications — technical included — are subject to change without notice.
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