Effects of lightning impulse on power transformer insulation level

The overvoltage stresses due to lightning impulse has been studied by using simulation tool and a typical Thailand subtransmission system. The effect of lightning is considered as backflashover at the insulator and shielding failure. Then, transmission line, tower, switchgear and transformer are modeled together as a system. The effect of tower footing resistance, underground cable connection between overhead line and switchgear as well as opened circuit breaker on overvoltage stress has been thoroughly investigated. The result is used to determine the insulation level of power transformer and other high voltage equipment in power system.

[1]  J.A. Martinez,et al.  Tower modeling for lightning analysis of overhead transmission lines , 2005, IEEE Power Engineering Society General Meeting, 2005.

[2]  C. L. Wagner,et al.  Insulation Coordination for Gas Insulated Substations , 1973 .

[3]  Juan A. Martinez-Velasco,et al.  Modeling of Overhead Transmission Lines for Lightning Studies , 2005 .

[5]  H. Elahi,et al.  Modeling guidelines for fast front transients , 1996 .

[6]  Wenxia Sima,et al.  The simulation model for calculating the surge impedance of a tower , 2004, Conference Record of the 2004 IEEE International Symposium on Electrical Insulation.