Deep Suppression of Switching Overvoltages in AC UHV Systems Using Low Residual Arresters

How to control overvoltages in ultra-high voltage (UHV) systems is critical to ensure their safe operations, and the switching overvoltage level is an essential aspect of insulation coordination. The deep suppression of switching overvoltage is thus a key issue of current ultra-high voltage (UHV) systems. Presently, the low residual voltage surge arresters and the arresters with controllable residual voltage are being developed. These new arresters could be an effective way to provide deep suppression of switching overvoltages in UHV systems. Simulations show that the low residual voltage arresters will dramatically reduce overvoltage levels of various types of switching overvoltages. Much lower overvoltage levels can be obtained by distributing arresters along the line. As a result of using these low residual voltage arresters, present overvoltage protection methodologies and insulation coordination rules will be changed; overvoltage withstand requirements for UHV power apparatus will be greatly reduced, and the closing resistors for breakers can be eliminated.