We conducted feasibility study on detection system for unexpected lightning damage (puncture of
blade skin) for wind turbine blade. When puncture of blade skin by lightning strike occurs elastic waves
may be generated and propagate on the blade. The elastic wave (longitudinal wave) is measured by
acceleration sensors at root part of the blade to detect puncture of the blade skin. The detection system
was validated by simulation test of lightning damage. We fabricated blade model for experiment. The
blade model was made from GFRP (Glass Fiber Reinforced Plastics), and the length is about 4 m.
Experiment was conducted at SHODEN Co., Ltd. by using a high voltage test device. The influence of the
electromagnetic noise on acceleration measurement can be negligible. In the experiment simulating
lightning strike on receptor, propagation of elastic wave was not observed clearly. On the other hand, in
the experiment simulating lightning strike on wind turbine blade, propagation of elastic wave was clearly
observed as a fluctuation of the acceleration. The propagation velocity was estimated about 2865 m/s by
using least-squares method. We concluded that the detection system might be feasible.
This study evaluates scanning Doppler Lidar-based wind field measurement and analysis
techniques for wind energy applications. The Lidar measurements are first validated against
measurements from existing V1 Lidar. It is found that the availability of 20% (30 data per 10 minutes) is
sufficient to produce fairly good 10 minutes averaged wind speed and direction. The vertical profile
measurements for wind blowing from land and that from sea are then performed using DBS configuration.
The averaged wind speed for the former is lower than for the later. Two more scan modes, RHI and PPI,
are employed to investigate the effect of coastal terrain on the near shore velocity profiles and to
characterize the wind turbine wake. An internal boundary layer develops from the shore and persists up to
2000 m offshore. Lidar measurement data are also used to validate numerical simulations by a mesoscale
model. The measured and predicted wind speeds agree well up to the height of 500 m. Finally,
measurements of flow field around wind turbine shows the velocity deficit in the wind turbine wake and
agree with those predicted by a wake model.