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When a wind turbine performance upgrade isn’t what it seems

Wind Turbine

How to avoid common pitfalls and protect your energy yield certainty

Over the past year, many of our customers have been approached by wind turbine manufacturers offering upgrade packages. Many upgrades are software updates, and some include hardware such as Vortex generators, which are attached to wind turbine blades and aim to improve the power, loads and the service life of a wind turbine.

These upgrades can have a positive uplift on energy yield and we have seen the claims of 1-2% annual energy uplift can be achieved for some types of upgrades.

While these upgrades have their clear advantages, there are also some potential pitfalls which need to be avoided. Unfortunately, some of our customers have had to learn this the hard way.

Protecting the performance of your wind plant

Knowing the performance of your wind plant is critical, it allows you to manage uncertainty over a long-term period, giving you the possibility to sell or re-finance your wind plant if needed. When installing an upgrade on all turbines at the same time with no consistent reference data, it is not possible to demonstrate that the upgrades have been installed correctly and any improvements in performance are not quantifiable. The wind speed readings from the turbines are not suitable for this.

This is exactly what happened to one of our customers recently, following the installation of an upgrade package. While assessing the customer’s site for re-financing we noticed that the upgrade package was incorrectly installed resulting in a downwards effect on performance. As the upgrade included all turbines and had an impact on anemometry, there was no method to complete an energy yield assessment to understand the forecasted electricity production and any uncertainty to the level demanded for a financial valuation.

The turbine manufacturer was instructed to fix the problem, but the customer now needs to collect operational data for another year to get a robust energy yield value for the site.

A different customer, expecting a low uncertainty on selling a portfolio of sites which had been operating for four years, found that a performance upgrades a year ago introduced an inconsistency in the reference data and reduced the amount of data which could assessed against long-term predictions. This resulted in a higher level of uncertainty in the energy yield assessment. With potentially far reaching consequences for the future economic efficiency of the wind farm.

Taking steps to avoid upgrade pitfalls

Validation on your wind farm can avoid both situations. There are ways to test the impact of upgrades without taking irreversible action. For example, a toggle test or a test where the system is installed on half the turbines within a site. If the impact of the upgrade is known, then the full period of operations can be used in the analysis resulting in a lower uncertainty and higher measure of the estimated wind yield exceeding expectations 90% of the time, known as the P90 value; an essential measure which forms the basis of most financial valuations. It also provides confirmation that the upgrades have been correctly installed.

In summary, there are significant gains to be made and it is possible to show those gains in the energy yield assessment. However, to avoid introducing additional uncertainty, care needs to be taken to quantify the improvements.

If you’re considering a wind turbine performance upgrade but you’re worried about the impact of energy yield certainty, you can contact our team for advice and guidance.

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