make_zpv

make_zpv(pv, nb, nl, f, Zb, Yd)

make_zpv() - Calculates loop impedances for all PV buses.

Zpv = make_zpv(pv,nb,nl,f,Zb,Yd)

Loop impedance of a PV bus is defined as impedance of the path between
the bus and the slack bus. The mutual impedance between two PV buses is
the impedance of the joint part of the two path going from each of the
PV buses to the slack bus. The impedances are calculated as bus voltages
in cases when at one of the PV buses we inject current of -1 A. All
voltages are calculated with the backward-forward sweep method. The
input variables are the vector of indicies with "from" buses for each
branch, the vector of branch impedances and indicies of PV buses.