Investigating Switching Surges On EHV Lines And Substations - A Practical Utility Case

Switching surges occur frequently in long transmission lines and high voltage substations. They pose a significant risk to system reliability, especially when a lot of power is being transmitted across a weakly interconnected transmission network. At Extra High Voltage (EHV) levels, the insulation coordination of transmission lines and substation equipment is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and single-phase reclosing. This paper analyzes the results of switching studies conducted on high voltage network owned by Salt River Project (SRP), a utility in Arizona. Different switching scenarios are simulated and corresponding surge levels are studied at specific points in the system. Also, critical lengths of transmission lines modeled using SRP data are determined, and the effect of a line modeled with critical length is studied. The substations and equipment are also modeled according to data provided by SRP. Simulations are performed in the PSCAD/EMTDC transients program, which is a professional simulation software used for conducting transient analyses.