Analysis of Switching Overvoltage and Suppression Measures in UHV Transmission Lines

As the ultrahigh-voltage (UHV) projects are rapidly developing, it is necessary to investigate the problems involved in overvoltage and insulation, thereby providing a technical basis for future UHV projects. The switching overvoltage of closing no-load lines was simulated and analyzed here using two kinds of typical UHV network structures: the power plant to the grid system and the grid-to-grid system. Different factors, such as line length, mode of operation on the power plant side, and short-circuit capacity, are considered. It is possible for lines shorter than 60 km to eliminate the closing resistor, determined by calculating the probability of flashover. We analyzed the phase selection closing in depth to inhibit the switching overvoltage and considered the factors such as phase deviation and the length of the line. Finally, the applicability of phase selection closing is put forward for lines of different lengths.