Accounting for wire saggingоn span of 220 kV OHL whendetermining current, induced in ground wire by phase current magnetic fields

Abstract

Overhead ground-wire cable (GW) is more prone to ice formation compared to 220 kV overhead lines. Ice-melting methods for GW using special power source have certain engineering constraints and required is connection of overhead line. Preventive heating of GW to above-zero temperature is an equivalent method to ice-melting. Preventive heating shall be provided by induction from electromagnetic field (EMF) of 220 kV overhead lines while in service. Induction methods of 220 kV OHL GW heating have been summarized and briefly described. Mathematical models of GW inductive heating do not consider the influence of wire and GW saggingon EMF parameters and equivalent circuit ground wire-earth. Therefore, sufficient mathematical model is required to use induction method of GW heating at 220 kV OHL segment. We propose induction heating for GW of double-circuit 220 kV OHL inclosed circuit ground wire-additional conductor top reventice formation. Mathematical model have been developed to calculate current, induced in circuit ground wire-additional conductor by magnetic fields of 220 kV OHL current while in service. Influence of wire and GW saggingon EMF parameters and equivalent circuit ground wire-additional conductor has been estimated. Due to mathematical model we could estimate induced current to prevent ice formation on GW of double-circuit 220 kV OHL while in service. Closed circuit ground wire-additional conductor is recommended for practical use, with capacitor loop included into circuit, its capacitance to be determined based on voltage resonance conditions.