How can I consider a UAV thrust power for wind effects?
As i understand your image:


$V_{uav}$ is the velocity of the plane relative to the air.
$V_{wind}$ is the velocity of the air relative to the ground.
$V_{ground}$ is the velocity of the plane relative to the ground.


If the UAV velocity is 10 m/s and the stall speed is 10 m/s the plane is at its limit of flying no matter what the wind speed is (neglecting turbulences). The relative speed of the plane and the air is crucial, this speed is mandatory for the physics beyond the lift.

There is simple equation how to calculate sum velocities. Note that they are vectors (speed and direction) not just numbers. $V_{wind}$ can be named as drift velocity.

$$\overrightarrow V_{ground}=\overrightarrow V_{uav}+\overrightarrow V_{wind}$$

If the wind direction is opposite to the plane direction its ground speed, at the stall limit, is smaller than the UAV limit. It can be zero (the plane seems stand still) or even negative (plane seems to reverse).

Side notes: $V_{uav}$ is The velocity a pilot cares the most, $V_{ground}$ is the velocity his manager cares. This wind effect is also the reason why flying wit tailwind is preferred by airlines - they spare fuel - and it is also the reason why takeoff and landing is preferred in headwind - you need shorter runway to start/land sucesfully. With tailwind the runway may not be long enough.