Induced Voltage of Overhead Ground Wires in 50 0-kV Single-Circuit Transmission Lines

General grounding method of overhead ground wires adopted in Chinese 500-kV transmission lines is usually optical fiber composite ground wire (OPGW) grounded at each tower while common ground wire (CGW) insulated with one point grounded. Energy loss of OPGW and high induced voltage of CGW is a problem to be concerned as to its values and control methods. Both field measurement and ATP-EMTP simulation of induced current and induced voltage of overhead ground wires in a 500-kV single-circuit transmission line are carried out in this paper. Quantitative data of induced current and energy loss show the urgent necessity to reduce the energy loss and change the grounding method of overhead ground wires. A no-loss method for ground wires is proposed by comparing advantages and disadvantages of three grounding methods of overhead ground wires, where both OPGW and CGW are insulated with one point grounded. Induced voltage is calculated in different transposition pitch and segment length of ground wires with grounding position at the end of the line or at the midpoint of transposition pitch and segment. It shows that induced voltage of ground wires grounded at the midpoint of transposition pitch and segment is half of which grounded at the end. Moreover, induced voltage of overhead ground wires can be reduced to 500 V or other limited values by choosing a reasonable transposition pitch and grounding position.