A Force for Wind Power Testing
In providing essential analytical modeling and test services for Lightning Phenomena Challenges in Wind Turbine Systems and Structures, NTS helps reduce project lifecycle testing costs, and provides valuable insight for key design decisions.
Our longtime involvement in the Wind Power industry features hands-on participation on the IEC TC-88 PT 24 committee (responsible for releasing the wind industry test standard IEC 61400-24) and the development of our analytical modeling capabilities. This enables our engineers to conduct the design evaluation and testing services your wind power products require.
Protecting Your Investments: Lightning Engineering and IEC 61400-24 Test Capabilities
Our turbine and blade manufacturer partners know all too well: Wind turbines are sitting ducks for weather assaults. Lightning strikes can cause significant damage, which can be extremely expensive to repair, or render a turbine completely inoperable.
These challenges, compounded by the fact that you’re tasked with enhancing the longevity and reliability of your product without compromising performance or increasing costs, calls for a trusted, experienced industry partner. For the electromagnetic phenomena services your successful wind power application requires, NTS offers:
Protection Design for:
- Blades, including traditional makeup, CFRP makeup, anti-ice/de-icing technology, electronic systems and control devices
- Supervisory Control and Data Acquisition (SCADA)
- Control Electronics
- Power Distribution
- Structural components, including hubs, spinners, nacelle, mechanical drive train and yaw control systems, tower installations, grounding and equipotential bonding
Numerical Simulation Services
- Blades with Candidate Protection Designs using COMSOL Multiphysics
- Blade, Hub, Nacelle, Tower and Earthing Installations to predict responses to lightning strikes and performance of protection designs
- Evaluation for protection devices (SPD, TVS, Shielding, etc.)
Exposure Assessments – Zoning (LPX) per IEC 61400-24
- Damage Risk Assessments on-site or off-site turbine inspections for incident investigation
- Retrofit Design Services
Protection Verification Services
Certification Test Planning and Documentation for:
- Direct Effects Test conducted on blade specimens up to 15 meters in length, in accordance with Annex D of IEC 61400-24
- High Voltage Strike Attachment Test
- Initial Leader Attachment (Type A and Type B test methods)
- Swept Channel Attachment
- High Current Physical Damage Tests
- Up to 200 kA with 6 MJ and 300 C via arc entry and conducted current
COMSOL Analytical Modeling for Turbine Systems and Structures
NTS modeling and analytical teams, working in tandem with our engineering services team, guides the selection of the most robust materials and connection methods. We thoroughly evaluate protection design materials and features such as connections, SPL and ETH pads to sustain effects of multiple strikes.
COMSOL is NTS’ preferred modeling environment. Our fully verified, industry standard modeling suite solves systems of differential and partial differential equations that comprise the materials and boundary conditions specified in the model.
The NTS modeling approach supports physics coupling such as heat transfer and currents, and provides a myriad of options for customizing and developing models for virtually any situation.
NTS has developed electromagnetic models for wind turbine blades, analyzing distributions between structural carbon and surface protection layers, determining transient voltages and currents to optimize lightning conductor locations, tolerances and more. We can accurately simulate the required IEC 62305 waveforms for all lightning protection levels (LPL).
Development and Replication Methodology
In general, models are built from decomposing CAD-level data into COMSOL native shapes. This allows the determination of electromagnetic importance, such as voltages or currents induced throughout the blade, including CFRP pultrusions, heater elements, surface protection layers and down conductors. Models capture critical design details such as material thicknesses, conductor routing and receptor locations. The evaluation exposes conductive materials and associated performance risks such as arcing between blade elements, excessive current in structures, and induced transients into control systems.
NTS models are built to simulate physics via Maxwell’s equations and to replicate the test setup (i.e. return paths to the generator). These are critical for initial model development. The replicated test setup results are compared with measurements taken, not tweaked to “match” the measurements.
Analysis and Validation Methodology
NTS engineers conduct analyses to evaluate current distributions for one or several candidate protection designs intended to conduct lightning current with lowest potential for damage or repair. For this model data to truly be considered high fidelity, it must be validated by replicating the exact measurements taken during laboratory tests and comparing them to the analytical data to determine correlation. These tests typically include:
- High voltage strike attachment tests on wingtips to determine likely attachment points, puncture possibilities and internal streamer locations.
- High current physical damage tests on a ~1m2 panel to determine current conduction efficacy of embedded lightning protection materials.
- Induced transient tests on internal wiring harnesses to assess induced voltage/current amplitudes and to evaluate the potential for damage to installed electrical equipment.
Comparisons are captured in a detailed Validation report that serves as the “Go or No Go” portion of the projects. If the model shows sufficient agreement with the measured data, it can then be deemed an appropriate representation of real test article. If the model does not show agreement, alternative modeling approaches can be taken, or the project can pause to reduce program risk. Experience to date has shown good correlation between model and measured data.
Validation and General Purpose
Once the model has been validated, it is returned to a general purpose setup. The boundary returns are used to remove any test-setup-specific artifacts that may have been included, and physics and boundary conditions are not changed. The model can then be manipulated without undergoing further tests; allowing for the examination of identified design changes warranted by initial model computations/data validation tests, and understanding transient levels on conductors and electronics.
Fully Developed Models
In collecting early lifecycle data, fully developed models allow for the examination of areas where measurements were or could not be taken, so better design decisions can be made. Early life cycle modeling reduces certification risks, verifies design methodologies for future (similar) designs, and allows for similarity analyses on future designs to reduce testing needs.
What can we do for you? To start the conversation about your Wind Power project, Request a Quote today.