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NEWA - Rödeser Berg 2017 - Blind Test

Site Description: 

The Forested Hill Experiment Kassel was conducted within the EU project NEWA – New European Wind Atlas (ERA-NET Plus, topic FP7-ENERGY.2013.10.1.2).

This field campaign provides a unique dataset of wind measurements for validating models for flow over forested hilly terrain. The experiment was conducted on the Rödeser Berg, a hill (380m height) near Kassel, Germany (see Fig. 1). In October 2016, a three month intensive campaign relying heavily on remote sensing devices, i.e. lidar and sodar wind measurement systems, marked the beginning of the experiment. At the same time a one year long-term campaign using two tall masts started.

Location of the Rödeser Berg site in central Germany.

Fig. 1: Location of the Rödeser Berg site in central Germany.

Fraunhofer IWES has conducted the measurement campaign in corporation with DTU Wind Energy. Furthermore ForWind, Enercon, innogy and Plankon/Innovent have provided wind measurement equipment fort the Forested Hill Experiment Kassel.

The Rödeser Berg site is located in the federal state Hessia (Germany), around 20km northwest of the city of Kassel. The terrain height is between 200 m and 400m (hill top) (see. Fig 2 – left). The hill site is characterized by broadleaf forests with some spots of coniferous wood. Tree heights are around 20-35 m (see. Fig. 2-right). The roughness length in the area is in the range of 0.03 to 0.75 m (see Fig. 3).

Topography of the site Forest heights

Fig. 2: Topography of the site (left) as well as forest heights in the same area (right). The red dot marks the position of the 200m met mast on top of the Rödeser Berg. Data Source (ALS data): Hessische Verwaltung für Bodenmanagement und Geoinformation]

Roughness length

Fig. 3: Roughness length distribution [based on CORINE-Dataset – EEA (2016)], converted to roughness lengths  with the method by Silva, et. al 2007.

In Spring of 2015 a wind farm, consisting of four Enercon E 101 (3MW, rotor diameter: 101m, hub height 35m) became operational at the site. These turbines are located northwest of the 200m met mast on the hill-top. 

Data Provider: 

Tobias Klaas, Paul Kühn (Fraunhofer IWES Kassel).

Data accesibility: 

The available test case data is released by Fraunhofer IWES as part of the NEWA (New European Wind Atlas) project.

Instrumentation: 

One of the tallest met masts in Germany; a 200 m Met mast is operated by Fraunhofer IWES on the top of the hill since 2011 (see Callies et al. (2017)). This met mast is equipped with cup and sonic anemometers at various heights. Besides these temperature and a temperature difference sensor enable the measurement of atmospheric stability in terms of the Obukhov length at the hill top.

For the experiments conducted within NEWA, a second 140m met mast was erected for one year along the prevailing wind direction axis in the inflow to the hill. This met mast was well equipped with sonic and cup anemometers in vertical distances of at least 20m.

Measurement Campaign: 

Within the New European Wind Atlas (NEWA) project an intense measurement campaign took place from October 2016 until January 2017 at the site. In total 17 measurement systems have been used: 9 lidar scanners, 5 lidar/sodar profilers and the 2 tall met masts.

Measurement devices

Fig. 4: Distribution of measurement devices during the intensive measurement campaign.

In addition to the met mast, three scanning and profiling lidars are of importance for the benchmarks. The positions of all for the benchmark relevant devices are marked in Figure 4. The UTM coordinates are presented in Table 1. 

Tab. 1: Distribution of measurement devices during the intensive measurement campaign.

DeviceTypeUTMX [m] – Zone 32 UUTMY [m]  – Zone 32 UElevation [m]
MM200Met Mast (hill top)5135905690182388.0
MM140

Met Mast (southwest of hill)

511589

5687521261.0
WS1 (Vara)Wind Scanner (RHI at MM140)5116415687591260.8
WS2 (#23)Wind Scanner (RHI at MM200)5135895690178392.8
WS6 (#58)Wind Scanner (RHI at MM200)5135885690176392.8
WP1Wind Profiler5148045691869254.6
WP3Wind Profiler5125555688544273.1
WP6Wind Profiler5116425687589260.8

For a much more detailed description on the measurement campaign and its installations, see: Callies, et. al. (2017).

Remarks: 

The prevailing wind direction at the site is south west. Consequently, the benchmarks will focus on the flow from this prevailing wind direction. For this wind direction none of the two met masts is influenced by the wakes of the wind turbines at the hill top. Thus, they do not need to be taken into account for this benchmark.

    Fig. 5: Terrain Height along the transect of 217 degrees (the red dots mark the positions of the met mastas MM140, MM200 and the wind profiler WP1 (from left ro right).

The scan direction along the hill ridge is always 217 degrees. Figure 5 shows the terrain height as well as the position of the measurement devices along this transect. The benchmarks will ask for extraction of 2D-planes from the simulation along this axis. Please note: The wind direction might differ by some degrees from this. The cases to simulate for the benchmark represent typical inflow conditions.

NDA: 

Referencing:
Please note: In case the terrain information (terrain height, terrain inclination, tree height, PAD) is used in any type of publication the provider of the data needs to be acknowledged as follows:  Data Source (ALS data): Hessische Verwaltung für Bodenmanagement und Geoinformation]

References: 

Callies, et al. (2017): NEWA EXPERIMENT DOCUMENTATION, Forested hill experiment Kassel, Technical Report.

EEA (2016): Corine Land Cover (CLC) 2012, Version 18.5.1, European Environmetn Agency (EEA) – Copernicus programme, dataset available online: (last visit: 09.11.2017)

Silva, et al. (2007): Roughness Length Classification of CORINE land cover classes, Proceedings of the European Wind Energy Conference, Milan, Iltay, 2007.