Task 43 Digital Calibration Certificate - An introduction

[heikowestermann]

Task 43 Digital Calibration Certificate - An introduction

Heiko Westermann, Deutsche WindGuard Wind Tunnel Services GmbH

As already laid out by Amit Bohara in his great introduction to the IEA Wind Task 43 WRA Data Model, there is a lot of incentive for a wind analyst to use a digital data model for wind resource assessment. Since sensor calibration data is usually reported in PDF documents that are not machine-readable, the same benefits of using a data model for calibration data (a "digital calibration certificate") apply.

In this short introduction to the Task 43 Digital Calibration Certificate, I want to focus on the specific benefits of using a digital calibration certificate for anemometer calibration data in conjunction with the Wind Resource Assessment Data Model.

Why?

If you start using the WRA data model you will quickly realize that efficiently filling such a model with data is still very much dependent on the source of the data. In the case of calibration data, there is no standard for a digital calibration certificate to rely on. Anemometer calibration certificates in a best-case scenario are delivered as a PDF and in a worst-case scenario as a paper printout. Regardless, extracting the data becomes a manual job which has to be repeated for every single calibration. In many cases, only the minimal required information is extracted, and the remaining data from the calibration certificate is disregarded.There are also obvious risks of error when transcribing the calibration manually by hand or using an OCR (optical character recognition) software.

An example of a poorly copied "analog" calibration certificate

Digital calibration certificate excerpt containing the same data as the above "analog" certificate

Task 43 Digital Calibration Certificate (DCC) for anemometer calibrations

We developed an open standard for anemometer calibration certificates, so that the end-users as well as the calibration labs can have a common ground to work with. The standard is meant to be simple to implement and contain all the data required by the IEC 61400-12-1:2017. It follows the same principles of the WRA data model in that it provides standard naming conventions and is human/machine friendly by being JSON-based. With the release of version v1 the digital calibration certificate is part of the WRA data model repository and can be used as of now.

Overview – The repository, including the documentation of the project, can be found here.

Sample data – An example of an “analog” calibration certificate as well as its digital representation according to the DCC can be found in the ‘demo_data’ folder here.

How to implement – This jupyter notebook gives a good example on how to parse the data in Python. It also shows how to validate that a given dataset conforms to the standard, which is helpful if you would like to generate the data yourself (calibration labs for example).

(Bonus) Delivery

If you would like to make use of the digital calibration certificate, please contact your calibration lab and ask them about the possibility of receiving your calibration certificates in this format.

Deutsche WindGuard Wind Tunnel Services is currently able to provide the DCC in multiple ways:

Text-File – We can supply the DCC as an additional file via our Cloud Storage.

PDF-Attachment – We will attach the DCC to our PDF certificates via the much-overlooked feature of PDF-Attachments.

API – We are about to introduce an API which makes way for the automatic retrieval of calibration certificates. If you are interested in exploring this option with us before the official release, please let us know.

If you would like to know more about our services, feel free to contact us at: [email protected]