CAPACITIVE COUPLING COMPENSATION FACILITATING SINGLE-POLE SWITCHING ON SIX-PHASE TRANSMISSION LINES (SECONDARY ARC, RECOVERY VOLTAGE)

In this research, a novel shunt compensation scheme design procedure is developed for unbalanced, untransposed n-phase transmission lines. The main function of the scheme is to reduce the effect of the capacitive coupling on untransposed transmission lines to levels where successful single-pole switching is assured. The analysis procedure is carried out for six-phase transmission lines, but it could be applied to any n-phase system.;The results indicate that without the shunt compensation the single-pole switching application to EHV six-phase transmission lines will not be successful. When the shunt compensation scheme is used, the magnitude and rate of rise of the recovery voltage, and the secondary arc current are reduced by more than 50% of their uncompensated values. These results indicate that single-pole switching application to the compensated lines is expected to be successful.;In the first part of the research, the arc characteristics for various gap lengths are investigated. The results of the investigation are utilized in developing the transmission line gap recovery characteristics. Equations that express the capacitively-coupled secondary arc current and recovery voltage in terms of line constants and the compensation scheme element values are derived. A digital computer is used to find the optimum compensation element values using these equations. Two existing transmission line data are utilized as a demonstration of the adequacy of the shunt compensation in reducing the secondary arc current and the recovery voltage. The performance of the compensation scheme under various line conditions is verified by simulating the line and the compensation bank using the Electromagnetic Transient digital computer program.