Magnetic and capacitive couplings influence on power losses in double circuit high voltage overhead transmission line

Abstract

PurposeThe paper aims to discuss problems of power and energy losses in a double-circuit overhead transmission line. It was observed from energy meters’ readings, that in such a line, active power losses can be measured as “negative”. The “negative” active power losses appear when the active power injected to the circuit is lower than the active power received at the circuit end. The purpose of this paper is to explain this phenomenon.Design/methodology/approachTheoretical considerations based on mathematical model of the transmission line of π-type confirming that effect are presented. Power losses related to series impedance of the line and to shunt admittance are calculated. The theoretical considerations are confirmed by measurements done on the real transmission line.FindingsThe calculations allow to indicate components of the active power losses, i.e. related to electromagnetic coupling among wires of a given circuit, related to electromagnetic coupling between circuits and related to shunt capacitance asymmetry. The authors indicate the influence of the line/wires geometry on the active power losses in a double-circuit overhead transmission line.Originality/valueExplanation of the effect of “negative” active power losses’ measurement in a double-circuit overhead transmission line is provided in this paper.