Distribution Networks Including the Power Lines with Prevailing Resistance

In power lines with prevailing wire resistance, voltage loss can be varied changing the cross-section area of the conductors on the path from the beginning to the consumer in question. The enlargement of cross-section area of wires of all line segments of the path should be such that the summary increase of wire cost is minimum. This occurs when derivatives of the wire costs by voltage loss of this wire for all segments of the path are equal. The said derivative can be determined using curves of conductor cost as function of current density. The lowest per unit of transferred energy cost of an optimum fed zone, with transformer located properly in the zone, takes place when, enlarging the zone, the decrement of transformer per unit cost equals to the increment of grid per unit cost. If for cost effective wires in optimum fed zone the condition of voltage loss is not met, the options should be considered increasing the cross-section of wires or decreasing the fed zone. If all necessary data are not possible, the said curve of cost versus current density can be built on the base of commerce data.