Study On Pollution Performance on a Wind Turbine Blade Using OES Technique for Lightning and Switching Impulse Voltage Profiles

Abstract

Lightning damage to offshore wind turbine power plants require an immediate attention, due to its severe damage to wind blade causing outage for a long time. The risk of lightning striking the blade is expected to be higher when they are located in a highly polluted and humid zone. Sodium chloride (NaCl) is considered to be among the severe pollutant near sea transported through air and gets deposited on the blade surface thereby increasing the surface conductivity of the material. Lightning can strike any part of the blade other than the receptors and the polluted surface with higher conductivity can allow discharge current to propagate over the surface thus causing severe burning of material and damaging the blade. Hence it is necessary to study the influence of salt deposit on a wind turbine blade injected with standard lightning impulse and switching impulse voltages. Wave profile and polarity has an effect during discharge because of its unique discharge formation process. Preliminary experiments are carried out in laboratory to study the influence of salt deposit on a blade sample by adopting IEC 60507 standards. Experimental results clearly show the extent of surface damage increases with increase in salt concentration. Optical emission based non-intrusive technique is used for an elemental analysis during the discharge process. Optical Emission Spectroscopy (OES) studies clearly show switching impulse voltage of both polarities induce a significant damage to the glass fiber reinforced plastic (GFRP) material.