Electric Secondary Distribution System Design

As energy prices and the costs of building new generating facilities continue to increase, electric utilities have started looking for ways to reduce system losses. The secondary distribution system is under scrutiny due to the large number of distribution transformers and high secondary load currents. A companion paper [1] presents a new method of secondary distribution system modeling and load characterization. The secondary distribution system is modeled in terms of a few secondary circuit archetypes. The power demand of each load is derived from actual energy consumption. A computer software using Microsoft Excel has been developed to calculate the losses for all transformer secondary circuits in the pilot area, including energy losses in the service drops, secondary lines, and transformers; thus, the circuits with the greatest losses are identified for further study. The applications of the proposed secondary distribution model and load characterization on the economic analysis and design of secondary circuits are also presented.