Lidar-assisted control (LAC) of wind turbines (WTs) has been an active area of research for over a decade. Both simulation-based studies and field testing campaigns show promising reductions in structural loads as well as increases in energy production using feedforward control relying on preview measurements of the approaching wind field. However, LAC has not become widely adopted by the wind industry yet. One of the most significant barriers to the widespread adoption of the technology is that guidelines for certifying WTs with LAC have not been established. Without clear design standards for WTs using LAC, it is difficult for wind turbine manufacturers to fully assess the value creation of the control technology and move forward with including it in a commercial turbine design.
The workshop “Certification of Lidar-Assisted Control Applications” brought together lidar manufacturers, wind turbine manufacturers, research organizations, and certification bodies to develop suggestions for guidelines for type certification of WTs with LAC.
The workshop was organized as a 2-day event:
- Day 1 began with an overview of type certification and how it is affected by LAC. The afternoon was devoted to presentations by the four stakeholder groups, all answering the question “what are the challenges for type certification with LAC?”
- On Day 2 the participants split into four working groups, rotating through four different stations, each hosted by an expert moderator, covering the following topics relevant to certification with LAC:
- The lidar system (Steffen Raach, sowento)
- Simulation models and load simulations (Claudia Meyer and Johan Olaison, DNV GL)
- Control and protection system (Reinhard Schleeßelmann, DNV GL)
- Prototype measurements (Andrew Scholbrock, NREL)
For each topic, the groups brainstormed and formulated ideas answering the question “how should we certify wind turbines with LAC?”
A variety of ideas were generated by the working groups along with new questions raised, with several themes emerging. One challenge highlighted is the certification of WTs using LAC for extreme load reduction. Because 100% lidar availability is unlikely, ensuring that either the lidar is functioning properly or the turbine is operating in a “safe mode” when extreme wind conditions occur is critical. Another topic addressed is how to reconcile site-specific lidar properties affecting LAC with more general WT type certification. Wind turbines are type certified for a specific wind class, but lidar availability, with implications for controller performance, depends on additional atmospheric conditions. Further themes addressed include the need for clarity in modeling lidar preview measurements in the extreme wind fields used for certain design load cases, as well as procedures for verifying the performance of the lidar and lidar-assisted controller during prototype testing. Lastly, one overarching point that was raised is that guidelines for certification of WTs with LAC should remain as general as possible and only address areas where LAC presents unique challenges not covered by existing design standards.
The ideas formulated during the workshop are being incorporated by some of the workshop participants into a document “Best Practices for Certification of Lidar-Assisted Control Applications,” which will be made available on the Task 32 website when complete. The content of this Task 32 document will be used by DNV GL as they create their guidelines on certifying WTs with LAC, planned for later in 2018.
The minutes, presentations, and other documents from this meeting are only available to logged-in members of IEA Wind Task 32. They include:
Welcome and Introduction
- Introduction to IEA Wind Task 32 (David Schlipf)
- Introduction to Lidar-Assisted Control (David Schlipf)
- Round-the-room Introductions (please contact us if you would like to add/update)
What is type certification and how is it affected by LAC?
- Overview of certification (Mike Woebbeking)
- Implications of LAC on the certification of Wind Turbines (Nikolai Hille)
- Introduction to ISO 13849: Safety-related parts of control systems (Reinhard Schleeßelmann)
What are the challenges for type certification with LAC for lidar manufacturers?
- Practical matters affecting the utility of nacelle mounted lidars for turbine loads measurements and control (Chris Slinger)
- Description of realistic lidar modelling and lessons learned from field tests for lidar-assisted turbine control (Shumpei Kameyama)
- The necessity of a representative Lidar simulator (Paul Mazoyer)
What are the challenges for type certification with LAC for turbine manufacturers?
- Lidar Assisted Control Application (Liu Lei). Unfortunately, this presentation could not be published.
- An industrial perspective on LAC at Envision Energy (Eric Simley)
What are the challenges for type certification with LAC for consultants?
- Considerations in Design Load Cases when using LIDAR Assisted Control (Oscar Hugues Salas)
- Prototype measurements on Wind Turbines – Considering LiDAR Assisted Control (Mike Lüdde)
- Cross-tool realistic lidar simulations (Steffen Raach)
What are the challenges for type certification with LAC for researchers?
- Lessons learned from field testing experience on using lidars with wind turbine controls (Andrew Scholbrock)
- Overview of traditional lidar modeling and wind evolution modeling methods (Eric Simley)
- Turbulent extreme event simulations for LAC (Tim Hagemann)
How should we certify wind turbines with LAC?
- Summary of Lidar discussion group Simulation model and load simulations (Johan Olaison)
Results from other groups are included in the minutes.