The way of reducing current values in optical ground wires at asymmetrical faults on overhead transmission lines

Georgiy Egamnazarov

Abstract


Giving the fact that the price of Optical Ground Wire directly depends on its cross-section, which in turn depends on the level of fault current it should withstand, the solution for reducing these current values by performing isolated descents of Optical Ground Wire with the transition it to an Optical Cable from the end towers of the line was studied. The research was carried out on example of 500 kV Overhead Transmission Line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used, therefore, fault current calculations were carried out on the base of presenting the overhead transmission line as multi wire system, for the considered case as five-wire system (optical ground wire, steel ground wire and three phase wires). Such approach allows to take into account initial asymmetry of parameters on overhead power transmission lines and to model any kind of asymmetrical faults. The analyses of calculated results are performed. The conclusive evidence that, the optical ground wire isolated descents from the end towers of the line, give the possibility of considerable reducing the level of maximal fault current distribution values in it, is presented

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Developed by Institute of Industrial Electronics and Electrical Engineering of RIGA TECHNICAL UNIVERSITY