Optimising operational wind farm performance

Overview

Octopus Investments is a leading investment manager in UK renewables energy, managing 2 GW of installed capacity.

After 16 months of operation, the client’s medium sized wind farm was showing signs of underperformance. Therefore, the client asked us if we could assist them with:

1. Undertaking a performance assessment for the wind farm, to investigate the root causes of underperformance to date, i.e. whether it had been caused by factors beyond the client’s control (such as wind variability), or factors that could be addressed operationally;
2. A full investigation of these sub-optimal issues so that they were truly understood, and provide advice on improving the asset’s performance.

How we helped

We began by analysing the 10-minute operational SCADA data including active power, ambient wind speed, pitch angle, generator and rotor speeds, nacelle direction and blade loads for each turbine, in order to determine production losses due to availability issues and sub-optimal curve performance. The production was adjusted to long-term in order to account for the effects of windiness during the operational period, followed by a validation of the pre-construction flow model.

We then investigated the potential causes for sub-optimal performance of the turbines in order to identify potential areas for improvement.

The Impact

Following our performance assessment, we concluded that:

• The operational period was a low wind period, producing approximately 8% less energy in comparison to the long-term average;
• The pre-construction energy yield prediction overestimated the production as a result of modelling errors;
• There has been up to 3.5% production loss due to suboptimal blade pitching. The sub-optimal blade pitching was identified through the correlation between normalised pitch angle below rated power and the power performance of the turbines. This finding was further confirmed by the step changes in blade loads.
• These findings have increased the understanding of the operational yield to date, itemising specific factors that may be responsible for underperformance. Potentially, the wind farm could improve performance by 3.5% with a corresponding increase in revenue if the pitch angle mismatch issues are resolved.