A Device and Method for Determining the Elemental Identity and Analysis on Moving Target from a Variable Stand-Off Distance

The invention relate to laser induced breakdown spectroscopy (LIBS) technique for detecting a contaminant or a pollutant layer on moving targets such as wind turbine blades. Wind power is one of important non-renewable energy sources. Its use in an offshore power generation application is increasing considering the energy crisis and global warming problem. Wind turbines power handling capacity varies from 30 kW to 7 MW. A typical 7 MW wind turbine has a tower height of 160 m and a rotor diameter of 164 m (i.e., Length of blades= 80 m). Wind turbines are open air structures often placed in isolated areas such as offshore and mountain regions where the wind condition is expected to be good and they are more prone to be affected by lightning strikes. Particularly lightning damage to a wind turbine blade are quite serious since the cost for replacements are remarkably high, laborious and time consuming. Lightning can be classified into upward and downward initiated with respect to tall structures and also classified based on its polarity (Positive/Negative), being that of charge transferred from cloud to ground. Wind turbines are more prone to be affected by upward initiated lightning, if its height exceeds above 100 meters. In order to prevent wind turbine blades from lightning damage, lightning protection systems, such as point receptors and metallic cap receptors are placed on blades to minimize the number of lightning strikes. Even though with this type of preventive measure in place to protect the blades from lightning damage, numerous lightning strikes to the wind turbine blades have been reported. That to the cost of wind turbine blade is about 15-20 % of the wind turbine system.

 

Applications:

LIBS technique can be utilized for detecting a contaminant layer on wind turbine blades. However, the height of wind turbine ranges from few tens of meters to hundreds of meters (100-200 m). Hence to detect pollutant on moving/rotating objects/targets, LIBS technique combined with a remote sensing approach with variable distance is essential. Based on the literature survey, there are no such devices to remotely measure and quantify the pollutant or contaminant on moving target.