APPROXIMATION FORMULAS FOR THE DISTRIBUTION-SYSTEM - THE LOSS FUNCTION AND VOLTAGE DEPENDENCE

The distribution system loss function and voltage dependence are examined and useful approximations derived that are analogous to the 'loss formulas' used in the transmission system. The approximations are used to estimate the losses and voltages in the distribution system under the conditions of varying the capacitive susceptance of capacitors installed in the system about the level corresponding to minimum losses and varying the tap-setting of transformers about the nominal tap setting. Theory is compared to loadflow calculations and a simple quadratic function is shown to be accurate in estimating the losses and to be consistently slightly conservative, where by conservative we mean that it overestimates the losses. The structure of the quadratic function is determined. A linear function is shown to be accurate for estimating voltages.