Lightning Protection: Securing Higher Reliability and Meeting the New Standards
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The document discusses lightning protection for wind turbines. It covers the new IEC 61400-24 standard which will require lightning testing for entire wind turbine systems. Analysis of lightning damage to over 500 turbines found that delamination and shell debonding were the most common types of damage. Explanations of failure mechanisms show that improper insulation allows lightning leaders to initiate from internal parts rather than just receptors. The presentation emphasizes the importance of robust lightning protection system design, testing, monitoring, and maintenance.
![Lightning Damages
Analysis
508 wind turbines (total power 997 MW) during 5
years operation in central USA
Blade length: 35 – 45 m; 304 damages
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Total damages
Distance from the tip [m]
Fiberglass blades
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Total damages
Distance from the tip [m]
Fiberglass/CFC blades
Source: Anna Candela Garolera et al, IEEE paper](https://image.slidesharecdn.com/bertelsen2016-08-31sandialabglpsfinal-160919174747/85/Lightning-Protection-Securing-Higher-Reliability-and-Meeting-the-New-Standards-8-320.jpg)
![Lightning Monitoring
Lightning Key Data® System
§ Avoid unnecessary inspections and
expensive downtime
§ Lightning Key Data® System measures
the lightning key figures when it strikes
and provides you with valuable data for
making the best decisions.
§ Peak current [kA]
§ Specific Energy [MJ/Ω]
§ Charge content [C]
§ Maximum rise time [kA/μs]](https://image.slidesharecdn.com/bertelsen2016-08-31sandialabglpsfinal-160919174747/85/Lightning-Protection-Securing-Higher-Reliability-and-Meeting-the-New-Standards-37-320.jpg)
Lightning Protection: Securing Higher Reliability and Meeting the New Standards
- 1. Lightning Protection: Securing Higher Reliability and Meeting the New Standards Sandia National Laboratories – 2016 Wind Turbine Blade Workshop EMPOWERING YOU TO TAKE CHARGE Kim Bertelsen – Global Lightning Protection Services A/S
- 2. OUTLINE 1. Introduction 2. News on IEC 61400-24 3. Lightning Damage Analysis 4. Explanations on failure mechanisms 5. Robustness in design 6. Lightning Monitoring 7. Conclusions
- 3. We are a full service provider in Lightning We provide solutions for: Wind Energy AerospaceBuildings and Plants
- 4. We are a global provider We offer lightning solutions for mission critical industries and international customers. • Established in 2007 • 42 employees • Present in Denmark, China and USA
- 5. Our services & solutions Infield Inspection Services Engineering Projects Laboratory Testing High Quality Solutions
- 6. EMPOWERING YOU TO TAKE CHARGE Lightning is predictable, controllable and the risk is preventable.
- 7. IEC 61400-24 Wind turbines – Part 24 Lightning Protection The 1st edition was published in 2010, 2nd version will be issued as a Committee Draft (CD) in October 2016 following the next meeting in Lisbon, Portugal • Test is becoming mandatory including High-voltage test and High-current physical damage testing – not only for blades but for the entire wind turbine application. • Description of similarity parameters between blade types, where the same LP system can be used across a blade family without requiring retesting • The standard includes blade exposure definitions, based on published field data • Blade zoning/Environmental definitions is required • Definition of lifetime is required • Recognition of numerical simulation, but requirements for modelling verification • Improved risk assessment guidelines including winter lightning and upward initiated strikes. • Requirements for Lightning Monitoring – if included News on IEC 61400-24
- 8. Lightning Damages Analysis 508 wind turbines (total power 997 MW) during 5 years operation in central USA Blade length: 35 – 45 m; 304 damages 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Total damages Distance from the tip [m] Fiberglass blades 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Total damages Distance from the tip [m] Fiberglass/CFC blades Source: Anna Candela Garolera et al, IEEE paper
- 9. Lightning Damages Analysis § Minor surface erosion on receptor § should be recorded as successful strikes. § This type of impact is not regarded as a damage, but as wear and tear § The receptor itself needs to be replaced in time § Shells will need to be restored § Receptor durability and replaceability can be an issue on severe sites with high lightning activity
- 10. Lightning Damages Analysis § Damage in front of the tip receptor § Caused by insufficient insulation of tip receptor parts inside the tip § Easy to repair, but difficult to improve to avoid repetition.
- 11. Lightning Damages Analysis § Most common damage close to the tip § Caused by insufficient insulation of conductor system § Relatively easy to repair § Often the lightning system is left as it was – resulting in same damage again
- 12. Lightning Damages Analysis § Attachment through shell to lightning cable - Shell delamination § Caused by insufficient insulation of conductor system § Relatively easy to repair § Often the lightning system is left as it was – resulting in same damage again
- 13. Lightning Damages Analysis § More severe damage with broken carbon structure § Caused by flash-over from lightning cable to carbon structure – due to missing coordination between the two systems § Shells are detached requiring significant repair work – eventually the blade needs to be replaced § Difficult to improve system during repair for avoiding repetition
- 14. Lightning Damages Analysis § Strike to lightning cable through blade shell resulting in trailing edge delamination due to high pressure inside the blade. § Caused by insufficient insulation of conductor system § Significant repair § Difficult to improve system during repair for avoiding repetition
- 15. Lightning Damages Analysis § The analysis shows the distribution of the lightning damages according to the damage types described above. § It is observed that the most common type of lightning damage is delamination, followed by debonding of the shells. § The shell- and tip detachment occurred only in 2.8% of the cases.
- 16. Lightning Damages Analysis § The analysis shows the distribution of the lightning damages according to the damage types described above. § It is observed that the most common type of lightning damage is delamination, followed by debonding of the shells. § The shell- and tip detachment occurred only in 2.8% of the cases.
- 17. Explanations on failure mechanisms § The lightning event is divided into different stages: § Leader Inception – where the turbine develops leaders due to high electric fields – and send out leaders toward the incoming lightning. § Leaders Interception – where an incepted leader connects with an cloud leader § Current conduction Phase § First Return Stroke § Subsequent Return strokes § Long Duration Stroke
- 18. Explanations on failure mechanisms Downward initiated strikes Charging Inception Current conduction
- 19. Explanations on failure mechanisms Upward initiated strikes
- 20. Explanations on failure mechanisms § Likelihood of upward lightning increases with turbine effective height § Often triggered by intra cloud discharges § Will not appear on public lightning detection and is therefore not included in i.e. § NLDN from Vaisala
- 21. Explanations on failure mechanisms § The root cause of most lightning damages are lightning leader initiation from internal parts – and not only from intended receptors Down condutorWeb/spar Tip receptor base Tip receptor Initial leader Cable overlamination
- 22. Explanations on failure mechanisms § In testing the same phenomenon is seem like this
- 23. Explanations on failure mechanisms § Or like this…… § In this area there is no receptors at all
- 24. Robustness in design What is robustness? § Step 1: § We need to implement a LP system where the internal conductive part cannot incept streamers – which requires careful insulation coordination § Only receptors can incept streamers – if the system should work. § The LP system needs to pass all high-voltage strike attachment tests and High- current physical damage tests – to show a strong tip receptor design – as well as a strong down conductor/interconnector system. § Step 2: § Robust LP systems need to be well tested to the limits - and beyond to define design margins. § Lifetime tests must be carried out to document that no degradation is taking place on non-replaceable parts – and to document wear and tear § The LP system needs to be maintained regularly based on life time definitions – and based on accumulated impacts to the specific blade.
- 25. Robustness in design Blade Zoning § GLPS has suggested a blade zoning concept to focus the efforts to the near-tip area.
- 26. Robustness in design GLPS solutions are inherently robust – and are designed and tested to be electrically independent on the blade structure. § Fully tested, meeting the requirements in the future IEC standards: § 200 kA § 10 MJ/Ω § 3.500 C § On request a GLPS solution can meet extended requirements for longer life time or i.e. winter lightning conditions § +200 kA § 20 MJ/Ω § 25.000 C § GLPS solutions comes with a component certificate and should always be certified together with the specific blade type – new or existing.
- 27. Carbon- and Complex blades § Carbon blades and complex blade including sensors, deicing systems etc. needs special attention. § No other electrical systems in the blade can be kept floating, but needs to be carefully integrated into the lightning system.
- 28. Robustness in design § The tip solution should ideally be a premanufactured component, that utilizes all the insulation and conductions capabilities need to demonstrate robustness in test and real life operation.
- 29. Robustness in design § GLPS tip
- 30. Robustness in design § GLPS side receptor
- 31. Robustness in design § The tip LP system tested as a naked system without blade shells. § The same test program as for a final verification test needs to be followed and passed. § Here attachment to the tip receptor
- 32. Robustness in design § And here attachment to the side receptor
- 33. Robustness in design § LP system implemented in a blade tip
- 34. Robustness in design § Glue is applied….
- 35. Robustness in design § Retrofit job almost done….
- 36. Robustness in design § Final verification test
- 37. Lightning Monitoring Lightning Key Data® System § Avoid unnecessary inspections and expensive downtime § Lightning Key Data® System measures the lightning key figures when it strikes and provides you with valuable data for making the best decisions. § Peak current [kA] § Specific Energy [MJ/Ω] § Charge content [C] § Maximum rise time [kA/μs]
- 38. Lightning Monitoring GPS Antenna Power Supply SPDs Power supply entry Heavy EMC box Comm. output Recorder PCB Sensor cables entry Amplifiers Sensor shielding clamps
- 39. Lightning Monitoring § Measurement characteristics § Current amplitude: +/- 240kA § Frequency range (-3dB range): 30mHz - 1MHz § Sampling frequency: 10MHz § Time frame recorded: 1.5s § Length of recorded waveform: 15M samples § Trigger level: Adjustable § Pre trigger: 100ms § Measurement resolution: 16bit § Time stamp accuracy: GPS/1ms § Backup of data to internal industrial grade SD card § Four characteristic parameters calculated from the full waveform § Full data set available after each measurement § Continuous measurement in full resolution of two subsequent events § Recording of all three channels simultaneously
- 40. Lightning Monitoring § The control unit is supposed to be installed in the hub – or in one of the blade roots. § The sensors can be installed in different positions depending on the LP systems configuration § Inside blade root on down conductor § On transfer system § Around blade
- 41. Lightning Monitoring § Final verification test
- 42. Lightning Monitoring § Parameter output
- 43. Lightning Monitoring § Parameter plots
- 44. Conclusions § Lightning is predictable, controllable and the risk is preventable. § A new version of the lightning standard IEC 61400-24 will be released soon. § Damages most often occurs to the outermost 1m of the blade, why this should be the focus. The rest of the blade should not be forgotten – but protection is not so demanding. § Robustness in LP systems can be achieved in a good combination between design and verification. § Blade with carbon fiber and complex blades with sensors and deicing systems needs special attention § Online lightning monitoring is available
- 45. EMPOWERING YOU TO TAKE CHARGEThank you!
- 46. EMPOWERING YOU TO TAKE CHARGE
- 48. Contact us Global Lightning Protection Services A/S HI-Park 445 DK-7400 Herning Denmark contact@global-lightning.com +45 70 26 02 11 global-lightning.com