I. Introduction
Over the past years wind energy is an increasingly significant source of renewable energy worldwide, in fact, 37% of the German electricity production from wind energy, that is to say around 60 GW net installed electricity generation [1]. Consequently, a major cause of concern came to the surface when it comes to maximizing the system reliability and availability thereby increasing the production (more revenue), for that reason, wind farm asset management (AM) is being highlighted [2]. AM in the context of maintenance represents 60% of the total AM cost mainly for Wind Turbine Generator (WTG) servicing and maintenance for durable assets of the wind farm [3].