"He who has kept a good diary is fortunate"

Thu, 05/01/2017 - 09:50

High operational availability of the wind turbines is a basic requirement for the economic operation of a wind farm - offshore even more so than onshore. Every day that a wind turbine at sea cannot operate is expensive. As part of Task 33 of the International Energy Agency, scientists and industry representatives have looked into the way in which standardized data collection, analysis and evaluation can contribute to the more efficient operation of offshore wind farms and have developed 10 main recommendations. OWI talked to Berthold Hahn, Head of the Department of Wind Farm Planning and Operation at the Fraunhofer IWES, about the compatibility of data, the cost of compilation and fading memory.

OWI: Mr. Hahn, why is it important to standardize the handling of data?

Berthold Hahn: Firstly, it is important to have systematic procedures, from data collection right up to its evaluation. This means that in order to obtain reliable information about avoidable maintenance tasks and stoppages, data must first be collected over a long period of time for all the wind turbines being observed and their problems, as well as the work that has been carried out on them. As soon as multiple turbine types or different service companies are being considered it will be necessary to deal with different data formats and varied naming of particular items. When comparisons are to be made with the results of other operators a unified language is essential. The more participants speak the same language – i.e.: use the same standards – the easier will be the data collection, communication, analysis and benchmarking.

OWI: You are promoting "from roles to taxonomies". What exactly is meant by this?

Hahn: In reality, the aims and requirements of the data users – mostly the operators/operations managers – are very diverse. A direct, concise recommendation for suitable guidelines is therefore impossible. We urgently recommend, firstly – looking to the future – to define one's own targets in relation to working with breakdown behaviour data and the performance of the turbines. It can then be determined step-by-step which raw data and evaluations are necessary. Only once this has been done can suitable guidelines be selected.

OWI: You have worked out 10 main recommendations, which also relate to the behaviour of the operator. Is the importance of data evaluation underestimated?

Hahn: In which form and quantity the operator/operations manager is provided with documentation of the maintenance work and data from the turbine control systems is fixed at the time the contracts are signed. This means that the analyses that are possible later are also fixed at a very early stage. In my opinion, which data is to be recorded during operation is often thought about much too late. Frequently, all the data that is produced anyway is recorded but gaps in this data are not recognized. In these cases, the realization that systematic data recording would have made sense first occurs when problems arise. In most cases, however, the missing information cannot be obtained retrospectively.

Experience can only be utilized when it has been obtained. But the memory fades over time. He who has kept a good diary is then fortunate.

OWI: Does standardized data evaluation mean more work or costs for the operators?

Hahn: Yes and no. Some evaluations are made available free of charge by manufacturers and service suppliers. In some cases this information will be sufficient, so that no additional costs are incurred by the operator/operations manager. In many cases, however, the operators/operations managers want more. And whoever compiles data according to unified guidelines, systematically, extensively automated and digitalized, decreases his costs and efforts in relation to his proprietary solutions for compilation and evaluation. Our opinion is that the later usage value is far greater than the effort required in organizing the dataflow.

OWI: You recommend the adaptation of established standards to suit the wind industry. Who needs to act now?

Hahn: This desire is the result of our internationally organized Task 33 of the IEA Wind, whose participants searched in vain for a complete norm tailored to wind energy. At a national level guidelines have already been formulated by the "Fördergesellschaft Windenergie und andere Erneuerbare Energien" (Federation of German Wind Power and Other Renewable Energies, FGW), which fulfil many of the desired points. These guidelines, which were created after industry requests, flowed into the recommendations, thereby achieving recognition and becoming better known.

Integrating the content into an international industry norm requires a further great effort. It would be very helpful if proponents of standardized data compilation and evaluation would contact the FGW in order to support a member of staff at the International Electrotechnical Commission (IEC) directly or indirectly. There, the fourth part of Norm 61400-26 "Operational Availability of Wind Turbines" will be created, which will be concerned with the reliability and the analysis of the breakdown behaviour of wind turbines. The head of the working group has already announced the intention to use the "Recommended Practices" of Task 33 as a basis, which would provide further recognition for the work and results of Task 33.

The interview was conducted by Katharina Wolf