Test, Measurement, and Monitoring

Wind Met Mast

The SWE’s three-sided wind met mast with a maximum height of 120 meters has multiple booms at various, freely selectable heights. Meteorological sensors (atmospheric pressure, temperature, humidity, rain) and wind sensors (cup anemometers, wind vanes, ultrasonic anemometers) can be mounted on these booms.

In combination with the SWE data acquisition system the met mast’s equipment allows the measurement of load and power performance curves of wind energy turbines according to IEC standards 61400-12 and 61400-13.

Ground-based Remote Sensing

LiDAR – short range up to 250m

The SWE’s short range LiDAR enables a simultaneous recording of horizontal wind speeds and wind directions at up to ten different heights between 40 and 250 meters above the ground. In flat terrain this type of wind measurement offers a good alternative to conventional wind met masts. Further research is required for the application of the LiDAR technique in forested areas and complex or mountainous terrains. In combination with a SWE developed scanner , the LiDAR device can be employed on the nacelle of a wind turbine. By a certain systematic control of the laser beam the air flow can be observed and analyzed either in front of or behind the turbine covering the entire swept rotor area at various distances from the nacelle. The information about the approaching wind field for example is used for the development of predictive control strategies or future performance and load measurements. By observing a wind turbine’s wake an estimation of the loads on neighboring wind turbines within a wind farm can be done.

LiDAR – long range up to 3000m

The SWE’s long range LiDAR enables a simultaneous analysis of air currents at different distances of up to 3000 meters from its location. By variable scanning mechanics measurements can be done within a hemispherical area around the device. As with the short range LiDAR-scanner, the laser beam can be steered in various, predefined directions.

Sodar

Surface-based remote sensing methods allow for a measurement of wind turbulence and temperature profiles in the atmospheric boundary layer with high vertical resolution (10 to 20 m). There are acoustic (SODAR), optical (windlidar) and electro-magnetic (RASS) techniques available.  A SODAR gives vertical profiles of the wind and the vertical component of turbulence intensity and qualitative hints on the vertical structure of the boundary layer. A wind lidar gives essentially the same data but has a higher range than a SODAR and offers a much enhanced data availability. A RASS gives the same data as a SODAR but additionally gives the vertical temperature profile. All these instruments are available at IMK-IFU.

KITcube

With KITcube the Institute for Meteorology and Climate Research at the Karlsruhe Institute of Technology comes with an excellent equipment of modern measurement instruments for experimental study of the atmosphere. The instruments for ground-based remote sensing of the atmosphere (radar and lidar) and the instruments for in-situ measurements (turbulence, radiation, measurement towers) are used worldwide in large international field programs.

The KITcube is an overall monitoring system that consists of different instruments to probe the atmosphere. It can survey an atmospheric volume of about 10 km side length with different methods and thus allows the temporally and spatially complete capturing of all relevant processes. The KITcube is characterized by high operational flexibility. It can be operated as a mobile device at arbitrary measuring locations as well as in continuous operation for atmospheric monitoring.

The primary purpose of the KITcube is to deal with essential questions related to turbulence and convection in the boundary layer and to the triggering of deep convection and subsequent precipitation caused by moisture variability, moisture convergence, convergence zones and aerosol distribution. In addition, the meteorological measurement platform can make a contribution for example to determine the radiation balance or in combination with air chemistry observations to characterize atmospheric aerosols.

Wind Met Mast

The SWE’s three-sided wind met mast with a maximum height of 120 meters has multiple booms at various, freely selectable heights. Meteorological sensors (atmospheric pressure, temperature, humidity, rain) and wind sensors (cup anemometers, wind vanes, ultrasonic anemometers) can be mounted on these booms.

In combination with the SWE data acquisition system the met mast’s equipment allows the measurement of load and power performance curves of wind energy turbines according to IEC standards 61400-12 and 61400-13.

MPA’s testing facilities enable full scale testing of large parts and components. Source: MPA Stuttgart

The Research Centre for Steel, Timber and Masonry (VAKA) provides more than 40 testing machines enabling a wide range of different investigations. Tests under static loading can be performed with loads of up to 28000 kN.

The MPA University of Stuttgart offers:

  • Servo hydraulic testing machines for static and dynamic tests
  • Large testing facilities with load floor and reaction walls
  • Large test set-up for realistic boundary conditions

The prerequisites for such multifaceted measurement tasks such as multiple measuring systems for large-scale tests, high frequency measurements for dynamic trials, stress analyses with strain gauges, or optical measurement systems are all present at the MPA. The instrumentations undergoing extreme conditions (such as offshore plants) have very high demands regarding their durability.

The MPA University of Stuttgart employs highly qualified personnel with years of experience who can ensure the durability of the instrumentation.

The Research Centre for Steel, Timber and Masonry VAKA provides more than 40 testing machines enabling a wide range of different investigations. Tests under dynamic loading can be performed up to a maximum load of 20000 kN.

 

The MPA University of Stuttgart offers:

  • Servo hydraulic testing machines for static and dynamic tests
  • Large testing facilities with load floor and reaction walls
  • Large test set-up for realistic boundary conditions

The prerequisites for such multifaceted measurement tasks such as multiple measuring systems for large-scale tests, high frequency measurements for dynamic trials, stress analyses with strain gauges, or optical measurement systems are all present at the MPA. The instrumentations undergoing extreme conditions (such as offshore plants) have very high demands regarding their durability.

The MPA University of Stuttgart employs highly qualified personnel with years of experience who can ensure the durability of the instrumentation.

VAKA’s services include the investigation of corrosion resistance of metallic and non-metallic coatings as well as components and products made of stainless steel.  Our Laboratory provides modern test facilities, such as a salt-spray-testing-machine and a corrosion meter for cyclic testing.

The MPA University of Stuttgart operates outdoor exposure testing set-ups and laboratories in which the influence of all relevant environmental conditions and atmospheres can be investigated over many years.

Sea water test (Offshore area / corrosivity category C5-M, CX according to ISO 9223 respectively) with the test areas:

  • Splash water zone
  • Alternate immersion zone
  • Submerge zone

Atmospheric test facility:

  • Stuttgart (corrosivity category C2 according to DIN EN ISO 12944-2)
  • Duisburg (corrosivity category C3 – C4 according to DIN EN ISO 12944-2)
  • Helgoland (corrosivity category C4 – C5-M according to DIN EN ISO 12944-2)
Atmospheric test facility. Source: MPA Stuttgart
Sea water test facility in Heligoland. Source: MPA Stuttgart

Laminar Wind Tunnel

The Laminar Wind Tunnel (LWT) is an Eiffel-type wind tunnel with a test section of 0.73m × 2.73m and 3.15m length and a turbulence level of Tux = 0.02% (f = 20 to 5000Hz) at 30m/s. It has a maximum operation speed of 90m/s. Its very low turbulence level makes it ideal for laminar boundary layer measurements and investigations of wind turbine airfoils. The measurement techniques of the LWT includes standard polar, pressure distribution, transition detection, boundary layer, two-point turbulent correlation, wall pressure fluctuations etc, acoustics measurement by microphone array and hot-wire based Coherent Particle Velocity (CPV) methods. Recently, the LWT was modified significantly and equipped with a sound absorbing lining in the diffusor between fan and test section.

Gust Wind Tunnel

The Gust Wind Tunnel is an Eiffel-type wind tunnel with a test section of 6.3m of diameter and a flow velocity of 17m/s. It is especially built for experiments with wind turbines under steady flow conditions as well as under gust loads.

The Stuttgart Wind Energy (SWE) chair at the University of Stuttgart has at its disposal measuring equipment to carry out noise measurements. This includes a suitably equipped noise level meter. In combination with simultaneous wind and power performance measurements on wind turbines, noise measurements can be carried out in accordance with IEC standard 61400-11.

Furthermore, frequency analyses can be done to examine solid-borne and airborne noise regarding tonality and pulsing.

The MPA University of Stuttgart offers expertise in

  • Design above fatigue and fracture mechanical assurance
  • Calculations over the entire life cycle
  • Evaluation of life cycle usage

Along with a large amount of standards and guidelines, for example DIN EN 13480, FKM-guidline, API 579-581 the tools allow for the evaluation with consideration of actual research results. AIM-Life and Xpipe which were specially developed by the MPA University of Stuttgart, compliment the current commercial software and are always updated using the most current research and development.

The current software tools, particularly in combination with methods of quality assurance, allow for dependable state evaluation of the structure and its components. They also allow for state-oriented management of inspection and maintenance procedures and dependable life-time estimation.

MISTRALWind: Monitoring and Inspection of Structures At Large Wind Turbines

Many established wind turbines are soon going to reach the end of their service life, which is 20 years.

In the course of the MistralWind research project a concept is being developed to enable further operation and thus a lengthening of the service life.

To reach this aim, inspection and monitoring systems for structures of wind turbines are being designed, adapted and applied.

At the MPA University of Stuttgart there are monitoring systems (both wireless and connected) available which are equipable with many types of sensors (humidity, temperature, strain, acceleration, cyclic velocity, displacement, and inclination).

The monitoring systems can be used for the entire wind turbine. The MPA’s special scope of capabilities includes:

  • State monitoring of rotor blades
  • Acoustic testing and analysis for the detection of failure processes and rubbing and clicking noises on defect sites
  • Calculation from static and dynamic part strain (i.e. via strain gauge); determination of load spectrum and detection of extreme loading
  • Electromechanical impedance measurements (using mounted piezoelectric elements) to determine stress states
  • Rotor blade position determination using acceleration sensors
  • Determination of temperature and humidity
Wireless monitoring of a bridge. Source: MPA Stuttgart

Mechanized ultrasonic testing on a rotor blade. Image: MPA Stuttgart

The MPA University of Stuttgart offers vast experience in the nondestructive testing of many different materials. The primary task of NDT is guaranteeing the necessary quality of components

Pre-commisioning:

  • Manufactoring defects
  • Design flaws
  • Damage due to transport and installation

In operation:

  • Operation due to operational stress (application of brakes, wind)
  • Damage from environment (water, ice, UV-light)
  • Damage from singular weather incidences (lightning, 50-year-gust)

There are various testing methods for rotor blades or parts made out of GFK and CFK:

  • Ultrasonic testing using through-transition and reflection
  • Local acoustic resonance spectroscopy (LARS)
  • Infrared thermography

Many of these methods were developed at the MPA University of Stuttgart for the rotor blade test. The above-mentioned methods can be used for quality management during the rotor blade manufacturing process as well as for condition control on the structure.