The problem of the actual insulation coordination for 500 kV with overvoltage in substations and the needed for more surge arresters in high voltage grid

Abstract

The new extra high voltage overhead lines and substations have increased the overvoltage phenomenon in the electrical interconnected system, especially in high voltage circuit breakers operate in a failure condition. This research develops a new methodology for transitory analysis, due to limits in the insulation coordination, available in the international standards IEC 60071, however it is not enough, more surge arresters should be required with the new overhead lines caused by overvoltage. The influence by lightning, circuit breaker failure (50BF), grounding system, towers and insulation chains are affected, in three-phase reclosing, maneuvers and transformer energization, finally a new assessment of the performance develops an accurate calculation of the overvoltage. Our findings are in the three-phase reclosing, the maneuvers have introduced overvoltage through the transmission line, higher values ​than 2.3625p.u. However, the insulation coordination is less than 2.32p.u.; compared with the limit of 2.28p.u. Finally, the overvoltage has increased from 160% to 258% according to the distance in the overhead line in 500 kV, with the needed of surge arresters, with the new equipment the overvoltage has decreased from 258% to 100%.