For oil & gas offshore as well as renewable energy, PhotonFirst has developed several applications. Especially in monitoring cables, predictive maintenance and blade deformation.
Please find our most relevant examples below:
- Wind turbine monitoring
- Wind turbine blade monitoring
- Underwater shape sensing
Wind turbine monitoring
Operation and maintenance (O&M) of offshore wind turbines is one of the main cost drivers of offshore wind energy today. Condition-based maintenance, instead of corrective maintenance, is becoming more and more a means to better control the O&M costs of wind turbines. All current known monitoring techniques have in common that useful information is provided after the components start to degrade or fail. Degradation of components is strongly related to the loads introduced via the rotor blades. Therefore PhotonFirst has co-developed a fibre-optic load monitoring system (FOBM) for commercial applications. Apart from load monitoring as input for condition based maintenance planning, the real time information can be used for e.g. individual pitch control (IPC), applied in order to reduce the loads on the blades. Already ongoing measurement campaigns in wind turbines using the desktop interrogator and prototype sensor design substantiate the tremendous usefulness of the load monitoring data. Current efforts focus on delivering a fully industrial validated product with EtherCAT data-interface and integrated wavelength reference. This ruggedized, small footprint interrogator is IP60 rated, shows outstanding stability and is already commercially available. In combination with the fully validated sensor rig a 6 months field test has proven the real time information usefulness for condition based maintenance and IPC, which results in a reduction of cost of energy of 0.4% in offshore wind.
Wind turbine blade monitoring
Developments in offshore wind are driven by an increasing size of the wind turbine power per unit. As a consequence the turbine blades become larger and more flexible. Designing these blades, current tools have insufficient accuracy showing up to 17% variations in stiffness. Ideal in harsh outdoor environments such as offshore wind is the use of light weight fibre optic sensing technologies. The ease of handling, high speed accurate data acquisition, small footprint, low price and minimum impact from the sensors on the material surface (aerodynamics) makes fibre optic sensing superior to the use of conventional strain gauges or for example visual monitoring using cameras. The PhotonFirst interrogator can log up to 120 optical Fibre Bragg Grating sensors divided over 15 channels using an optical switch allowing for channel multiplexing over different fibres with a sampling rate of >19 kHz per channel and a measurement frequency over 15 channels of up to 70 Hz. A feasibility study is performed modelling the wind turbine blade and the desired accuracy to determine to optimum amount and placement of the optical sensors. Extrapolating the modelling results onto a real-life blade test proved that optical point-sensing accurately records the in-plane, out-of-plane and torsional deformations in a wind turbine blade.
Underwater shape sensing
The DeepGreen500 European project offers a solution for harvesting energy from tidal and ocean currents, in harmony with marine eco system, with a low average cost of energy (COE). In this collaboration project with Minesto a 500kW tidal power plant in form of a “flying” kite tethered to the sea floor is developed. Integrated photonics sensing technology is used in the realization of a monitoring system for tracking the kite’s movements by means of implementing a shape sensing system inside the tether. Dedicated designed strips can hold up to five optical sensors, four measuring deformation induced wavelength shifts (strain) and one measuring temperature. Using the strain information, the bending radius of the strip is calculated. Interpolation of the bending radius in between multiple strips result in an accurate shape reconstruction of the 26m tether length. Any possible thermal influences can be corrected for using the temperature recordings. Such application requiring multiple optical fibres the PhotonFirst interrogator is ideal to use. Multiplexing up to 15 channels with data acquisition of >19kHz per channel, allows for easy real time shape reconstruction in combination with a dedicated software. The full system tests have proven the system functionality in lab environment.
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