On the Unity Row Summation and Real Valued Nature of the $F_{LG}$ Matrix

Electrical power system calculations rely heavily on the $Y_{bus}$ matrix, which is the Laplacian matrix of the network under study, weighted by the complex-valued admittance of each branch. It is often useful to partition the $Y_{bus}$ into four submatrices, to separately quantify the connectivity between and among the load and generation nodes in the network. Simple manipulation of these submatrices gives the $F_{LG}$ matrix, which offers useful insights on how voltage deviations propagate through a power system and on how energy losses may be minimized. Various authors have observed that in practice the elements of $F_{LG}$ are real-valued and its rows sum close to one: the present paper explains and proves these properties.