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Poster De Conférence Année : 2022

The Challenge of Repowering from the Energy Yield Assessment Point of View

Résumé

Repowering is the process of replacing older power stations with newer ones that either have a greater nameplate capacity or more efficiency which results in a net increase of power generated. Repowering has an international dimension and it is an emerging area of research due to the multiple challenges. Given the ambitious objectives of different countries to reach a high share of renewables by 2030 and beyond, repowering is a lever that contributes to this objective. Indeed, in the majority of cases the capacity factor is higher and can even double for repowered wind farms. This means that the most recent wind turbines can drastically contribute to a better wind farm performance. For 2030 wind farm reaching end of life represents a cumulated capacity between 40 and 82 GW in Europe. WindEurope, the European Wind energy Association, estimates that the yearly repowering volume grows from 1-2 GW in 2017 and stabilises to 5.5-8.5 GW by 2027. In USA, the repowering volumes may reach 2.5GW per year by 2027. The repowering of a wind farm undergoes the same decision process than any "greenfield" project. The energy yield assessment (EYA) is a supporting element of this process. Typical "greenfield" EYA comes with an uncertainty of 10-12%, even higher for complex terrain. There is no consensus on the values of uncertainties and several studies have shown a level of discrepancy in methods and uncertainty assessment. Nonetheless, the losses estimation, the wind speed long term extrapolation and the power curve uncertainty are acknowledged to be prevailing in the uncertainty budget. The repowering offers an opportunity to reduce these uncertainties using the historical production data. This directly impacts the P90 of the predicted production and therefor the wind farm net value. The typical methods for estimating the energy yield for repowered wind farms eitherconsist of performing a "greenfield" method and therefor neglect the benefits of existing data or assessing a repowering coefficient that multiplies the potential energy of the existing wind farm. The latter comes with challenges such as productoin losses identification, power curve assessment, long term extrapolation. These are similar to the "greenfield" process however the method relies on existing data and the associated uncertainty could be lower. In this work, we present the existing method to perform the assessment of the potential energy of a running wind farm. We highlight the challenges associated with this method in comparison to the "greenfield" method. We focus on the losses estimation based on production data and the associated data handling challenges, including the machine learning technics. We also look at the reference power production issues for specific cases of under performances due to sub optimal wind turbine behavior or environmental effects such as icing. We finally look at the subtle issue of wake impact on power production for the case of under-performing wind turbines. The study is based on existing literature and analysis of SCADA data from two wind farms. It aims at giving a comprehensive view on the existing method and identifying the outlooks of repowering in the case of EYA.
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Dates et versions

hal-03620438 , version 1 (25-03-2022)

Identifiants

  • HAL Id : hal-03620438 , version 1

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Paul Mazoyer, Thomas Duc, Georges Kariniotakis, Andreas Bechmann. The Challenge of Repowering from the Energy Yield Assessment Point of View. Wind Europe Annual Event 2022, Apr 2022, Bilbao, Spain. , 2022. ⟨hal-03620438⟩
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