Engineering speed modelling of realistic fatigue for all the individual turbines in wind parks by representative pre-calculations

Vindparker er svært kompliserte systemer. En vindpark består av mange turbiner hvis oppførsel er avhengig av været og de andre turbiner i vindparken. Slitasje på forskjellige turbiner i en vindpark kan variere mye. Noen turbiner vindpark kan for eksempel bli utslitt etter 20 år, mens andre har mange års gjenværende levetid. Å simulere vindparker er vanskelig for praktiske industrielle formål. Man kan bruke meget avanserte vindturbinsimulator som gjør en god jobb med å estimere oppførselen til hver turbin. Dette kan imidlertid kreve så mye regnekraft og tid er at det ikke er praktisk gjennomførbart. En annen måte er å bruke mye enklere simuleringsverktøy som er raske nok til praktisk bruk, men de er imidlertid mindre realistiske. Vi har en oppfinnsom tilnærming i vårt NEXTFARM-prosjekt som vi tror kan løse dilemmaet. Vi angriper problemet fra det enkelte turbins perspektiv. Den bryr seg bare om vinden som treffer den og ikke om hva det skyldes. Hvis vi kan beskrive alle vindforholdene som de enkelte turbinene i en vindpark kan oppleve, så kan vi bruke dette i en vindturbinsimulator og realistisk forutsi atferden for enhver tilstand. Mange tusen vindturbin simuleringer er nødvendig for å dekke alle mulige situasjoner, men det gjøres bare en gang. Vi kan så bruke en rask vindparksimulator og erstatte dens svært forenklede vindturbinadferd med våre forhåndsberegnede simuleringsresultater. En slik vindpark simulator kunne simulere hele levetiden til en vindmøllepark i løpet av få minutter. Det vil gjøre det mulig for ingeniører å designe billigere ny vindpark. Det vil gjøre det mulig for vindparkoperatører med en eksisterende vindpark å kjøre den lengre og mer effektivt. Begge bruksområdene vil bidra til å redusere kostnadene for fornybar og miljøvennlig elektrisitet fra vindparker på land eller offshore.

The project conducted perhaps the most thorough benchmarking of leading Dynamic Wake Meandering (DWM) models and high-fidelity Computational Fluid Dynamics (CFD) wind farm models ever undertaken. IFE and NTNU utilized the developed DWM wind farm model, WIFET Farm. DTU deployed their DWM model, while NREL used their FAST.Farm model. Uppsala University conducted the supercomputer CFD simulations. The models were compared with respect to power, loads, and fatigue. The DWM models were also compared with detailed full-scale measurements from the Lillgrund offshore wind farm, provided by Vattenfall and Siemens Gamesa. This work made it possible to identify and address the strengths and weaknesses of the various choices of sub-models that all DWM models are built from. This, in turn, has advanced the DWM wind farm wake modeling research field to a new level of realism. The project developed a new DWM model, WIFET Farm, which is easy to use, fast, and well-suited for industry use. It performed well compared to the other DWM models. The project has significantly advanced the international DWM wind farm modeling research field. International leaders in the field, DTU and NREL, have planned or started work based on the project's findings. In Norway, IFE has built competence that places it at the forefront of international research in DWM wind farm modeling. DWM models are arguably the most realistic yet practical tools for industry purposes. They can improve the economy of wind farms in the planning and engineering phase, during operation, and for lifetime planning and extension. The project has produced improved competence and tools that are now available to the industry, enhancing the industry's understanding of DWM wind farm modeling. Improved DWM knowledge and tools will reduce the cost of wind energy, which holds significant value and importance for society.

The project will be divided in three phases, In the first part a simplified and parameter-based version of a wake model will be developed, in order to achieve engineering friendly computational speeds for our turbine inflow model, a reduced version of the Dynamic Meandering Wake model (DWM) will be developed. In particular, the problem will be treated from the point of view of the single turbine, rather than of the whole wind park. The main assumption is that, deep within the interacting wind park, a turbine will experience only the wakes of the closest upstream turbines as concentrated, meandering wakes. This means concentrated wakes will be shed by turbines from maximum one or two rows upstream, positioned in a certain angular sector, aligned with the wind direction. The wakes of the turbines further upstream will be experienced only as a diffused wakes, generating a deep wind park velocity deficit. In the second part of the project, direct correlations between fatigue and local inflow for each turbine will be evaluated, studied, developed. This will be done either by simulating a large number of load cases and evaluating the resultant matrix. Advanced algorhitms for complex systems and matrix reduction will be studied in order to reduce the resultant matrix and generate a look up table that can be used to directly estimate fatigue from local inflow condition. The resultant model will then be successively verified and validated against other similar models and against full scale available data. In the third phase of the project, the developed tools and models will be applied to cost models and their impact on the wind park LCOE of a farm will be studied