Determination of Feeder Losses by an Improved Linear Model in a Radial Circuit

Feeder losses play an important role in the economics of a distribution system. In the traditional power flow analysis algorithms, the losses are determined as a follow up of the feeder voltages and currents. In this paper the line flow based analysis proposed by Yan and Sekar (2005) is extended to derive an improved linear model that can directly evaluate the losses with sufficiently good accuracy. The proposed technique uses feeder section power and reactive power and the receiving end voltage as the variables to be determined. After writing line voltage equations and power and reactive power balance equations at each feeder section, the improved linear model is derived using the Taylor series expansion. The improved model is applied to the standard IEEE 13 Node Test Feeder distribution system and shown to provide the losses quite accurately. The paper provides extensions of application of the model to solve some practical problems.