Wind Farm Life Extension

The first phase of the analysis involves detailed modeling of wind conditions, including:

• Actual site turbulence.
• Vertical shear and wind inflow angles.
• Weibull distributions per calculation cell.

This input is critical for accurate aeroelastic load calculations, allowing assessment of how real wind conditions affect the structure of each wind turbine.

The second phase evaluates the actual operational behavior of each unit, including, but not limited to:

• Wind-speed transients and alarms.
• Yaw misalignments during production and idling.
• Additional loads from ice accumulation.
• Extended or seasonal shutdowns.
• Blade surface degradation.

O&M track records (Work Orders) and relevant reports that may have affected operation are also reviewed and integrated into the analysis.

This information is consolidated to accurately represent the asset’s actual operating behavior.

In this phase, aeroelastic models are developed for each turbine type and configuration, representing the turbine’s actual structural and dynamic behavior.

The models are built considering the turbine’s technical characteristics (geometry, structural properties, control systems, and operational conditions) and undergo internal validation and consistency checks to ensure their reliability for load and remaining-life analysis.

These models form the technical foundation for subsequent structural evaluations.

In the fourth phase, aeroelastic simulations are performed under both design conditions and actual site conditions. This allows for:

• Calculation of load maps and cumulative fatigue damage spectra.
• Determination of the effective life of each structural component.
• Estimation of expected life per calculation cell and per turbine unit.

With this data, it is possible to accurately identify the most effective life extension actions and establish a component-level risk hierarchy.

The fifth phase of the analysis addresses uncertainties associated with each component, using proprietary protocols based on FMECA (Failure Modes, Effects, and Criticality Analysis).

This study quantifies the uncertainty of key variables and processes affecting life calculations, including:

• Historical and current wind-farm data.
• Wind characterization.
• Operational and maintenance information.
• Aeroelastic turbine model.
• Calculation methods and generated reports.

Additionally, 241 critical parameters are tracked and scored according to:

• Data criticality level.
• Source of origin.
• Scenario selected for the analysis.

This approach enables assessment of risk and reliability of predictions, providing a solid foundation for operational and strategic decision-making.

In this phase, the maintenance strategy is adjusted to the turbine’s actual operating conditions and estimated structural condition.

Based on the analysis results, critical components and relevant degradation mechanisms are identified, defining:

• Inspection priorities.
• Adjustments to preventive maintenance frequencies.
• Specific mitigation or reinforcement actions.
• Recommendations to optimize availability and reliability.

The goal is to align the O&M plan with the asset’s actual behavior, reducing technical uncertainty and optimizing costs over the extended service life.

Based on structural results and Reliability Models, technical-financial scenarios are developed that integrate failure probability, expected degradation, and risk exposure over the extended service life.

The scenarios are configured according to:

• O&M contract model.
• Energy prices and market incentives.
• Applicable regulations.
• Adopted maintenance strategies.
• Opportunities for partial or full repowering.
• Impact on cash flows and debt service capacity.

This analysis allows for an integrated assessment of technical risk and the financial sustainability of the asset.

Opportunities for partial or full repowering are evaluated, both in the pre-construction phase and on operating assets, analyzing their technical feasibility and structural, operational, and financial impact.

The analysis considers:

• Structural compatibility and resulting loads.
• Integration with existing infrastructure.
• Impact on production and reliability.
• Applicable regulatory requirements and permits.
• Economic and financial comparison with life extension strategies.

This approach allows determination of whether repowering represents the optimal alternative compared to extended-life operation.

Development of a preliminary characterization of the wind resource and operational conditions, following the conceptual approach of P80/P90 but with a simplified level of detail.

Parameters typically associated with IEC classification are evaluated, including:

• Mean Wind Speed (MWS).
• Turbulence Intensity (TI).
• Wind Speed Distribution (Weibull).
• Vertical profile and shear.
• Representative extreme conditions (indicative assessment).

Comparison of Type (design) conditions versus actual Site conditions using Nabla’s analytical database.

The Type vs. Site comparison, together with a preliminary life-consumption estimate based on prior analytical results compatible with the case study, allows for:

• Identification of life extension potential.
• Estimation of structural exposure levels representative of the site and platform.
• Derivation of indicative component-level failure probabilities.

Based on structural results and Reliability Models, technical-financial scenarios are developed that integrate failure probability, expected degradation, and risk exposure over the extended service life.

The scenarios are configured according to:

• O&M contract model.
• Energy prices and market incentives.
• Applicable regulations.
• Adopted maintenance strategies.
• Opportunities for partial or full repowering.
• Impact on cash flows and debt service capacity.

This analysis enables an integrated assessment of technical risk and the financial sustainability of the asset.

In the pre-construction phase, or during partial or full repowering, the High Level Analysis (HLA) enables early assessment of site-platform suitability without the need to develop specific aeroelastic models.

The analysis includes:

• Preliminary Site vs. Platform evaluation.
• Simplified characterization of IEC conditions (Mean Wind Speed, TI, shear, representative extremes).
• Indicative life-consumption estimate based on prior analytical results compatible with the case study.
• Identification of life extension potential and structural exposure.
• Technical support for IEC class selection and initial configuration.

This approach provides a solid technical foundation for early design, investment, and contractual structuring decisions.

Development of a wind farm Risk Map based on:

• Structural life results (P90, P80, or P70).
• O&M track records (Work Orders) and historical operational data.
• Relevant technical information by platform and site.

Fatigue-driven and random failure rates are profiled for structural, rotational, and electrical components, providing a quantified representation of risk by component and by asset.

Mapping of maintenance CAPEX and OPEX (Preventive and Corrective) aligned with the wind farm Global Risk Map

The model incorporates:

• O&M, repair, and replacement costs.
• Downtime versus energy price.
• Applicable regulatory framework and incentives.
• Site logistics and accessibility.
• Current maintenance contract and contractual structure.

The result is a structured estimate of life-extension costs and their impact on cash flows.

Adaptation of the model to different maintenance and asset management strategies:

• FSA (Full Service Agreement).
• Limited scope / split contract.
• Optimized maintenance strategies.
• Gradual dismantling.
• Partial or full repowering.

This produces a financial sensitivity study and key inputs for the financial model, enabling comparison of different business cases and investment strategies.