The Impact of Transients on Wind Turbines: Aligning with Operational Strategies
In recent years, the operational regime of many wind farms has changed significantly. Demands from grid operators, participation in secondary markets, avifauna restrictions, or revenue optimization strategies are driving an increase in the number of transients (start-ups and shutdowns) in wind turbines.
What might initially seem like a simple operational adjustment, however, has structural and mechanical implications that need to be properly quantified.
Each shutdown and start-up introduces dynamic transients that are not present during steady operation. During these phases, the turbine passes through critical speed ranges, torque changes, load variations, and moments that directly impact components such as the gearbox, generator, nacelle, blades, and foundation, each in a different way. In certain turbine models and configurations, these events can generate load levels higher than those considered for some components, requiring specific studies to effectively mitigate the risk.
In Nabla’s experience, the cumulative effect of these transients can be comparable, for certain components, to the fatigue damage caused by operating a few additional hours at nominal load, especially depending on the speeds at which these transients occur (or are planned to occur in the future). However, in many cases, the number of transients is monitored only from an operational standpoint, without integrating their structural impact into the actual consumed life balance.
This is particularly relevant for:
- Assets that participate intensively in regulation or ancillary service markets.
- Wind farms subject to avifauna-related shutdown protocols.
- Fleets with intermittent operational restrictions (curtailment).
The key point is that this effect is not theoretical, it is measurable.
By analyzing SCADA data and event logs, the operational history of turbines can be quantified to evaluate past performance and prepare future scenarios. Following this analysis, using aeroelastic models specific to each turbine and subsequent fatigue accumulation assessment, it is possible to quantify the real impact of start-ups and shutdowns on critical components. In some recent studies conducted by our team, it has been observed that a significant increase in the annual number of transients at certain speeds can alter load distribution, modifying the accumulated damage profile relative to the farm’s normal scenario, particularly for specific components. It is worth emphasizing that, at Nabla, these future scenarios are usually developed through sensitivity studies using tools such as Monte Carlo simulations to obtain component damage–based risk profiles.
The objective is not necessarily to avoid these operational strategies (many are economically optimal) but to understand their structural cost and manage them in an informed and controlled way.
In a context where life extension, OPEX optimization, and technical risk management are priorities, ignoring the effect of transients can lead to incomplete decisions. Conversely, incorporating their impact into the overall asset analysis enables:
- Adjustment of operational strategies.
- Refinement of remaining life estimates, allowing for proactive inspections or interventions and aligning maintenance protocols with operations.
- Stronger negotiation in contractual or insurance contexts.
The energy transition is transforming not only the amount of power produced by wind turbines but also the way production is carried out. And it is in this “how” that a significant portion of future structural risk lies.
The good news is that this risk can be modeled, quantified, and managed. Doing so rigorously marks the difference between reactive operation and a truly informed strategy.
To explore how to turn this analysis into concrete operational decisions, you can consult our Damage Mitigation Program and O&M optimization and contact us for more information on how to apply it to your wind farm.
