Optimizing iterated objective function – containing ∑- sum operator

I am going to minimize this power loss and voltage deviation separately-please see the attached image. My problem is i have no idea how to formulate the objective function from the given formula to solve objective function. help me to formulate objective function. Thanks in advance.

[Walter Roberson]

Which variables are inputs and which ones are to be altered?

You do not mention x or u on the right hand side, so it is not clear how they are involved?

[Kelzang choden]

This are the variables and the variables that need to be optimize /altered are the control variable (u)