Hi Ashish - Your logic sounds correct and the function comments seem to support what you have in mind.
In the past, when I've had to do something similar, I would use the Vincenty algorithm to compute the range and bearing of a point (latitude and longitude of (say) a wind turbine) from a reference position (latitude and longitude of the centre of a farm). This range and bearing can then be translated into an (x,y) position relative to the centre (0,0). It is computationally more expensive than the above, making certain assumptions about the earth (i.e. not spherical).
These algorithms can also be found on the MATLAB file exchange: vincenty code. Just look for the one titled "Vectorized geodetic distance and azimuth on the WGS84 earth ellipsoid".
There probably won't be much (if any) of a difference between this and your suggestion (with respect to the found coordinates). Just an alternative for interest's sake.
Geoff
