Back Flashover Analysis Improvement of a 220 kV Double Circuit Transmission Line

Abstract

The objective of this paper, is to design a 220kV double circuit transmission model, which includes six insulator strings with six cross arms and other components of the Transmission line i.e phase and ground conductors, line towers associated grounding systems with a surge of 100KA, 4/10 μs. The transmission line and back flashover event was modeled by frequency dependent fast front transient models due to the nature of higher frequency dependency of lightning strokes typically ranging from 1KHZ to 30 MHZ. Tower with two OHGW was taken in this work. Back flash over mechanism is modeled and triggered to the existing system by an external control module with powerful electrical tool PSCAD/EMTDC. Metal Oxide Transmission Line Arresters were used in this work as a solution for the back flashover. However, considering acceptable probabilistic failure as one outage per year per 100km line length, and suggested basic insulation level (BIL) of 1050KV, the arrester rating was calculated to be 196KV and its parametric determination for a one column arrester with an overall length of 1.45 meters is done. Simulation is carried out by placing Metal Oxide Arrester in each phase and recovering the string voltage without causing violent impact to the power grid.

Effect of waveform and impulse resistance on lightning performance in distribution system

“…Like the 5/350 /lS testing, the system can stand from the critical current of lightning current waveform lower than 10/350 /lS as shown in Table IV. Then BFOR are calculated by (5)- (8). BFOR results are shown in Tables V and Table VI .…”

Impact of Earthing System Designs and Soil Characteristics on Tower Footing Impedance and Ground Potential Rise: A Modelling Approach for Sustainable Power Operation

“…When lightning strikes directly to the tower, a high lightning current (typically in the order of greater than 20 kA for the case of backflashover [7,8]) will flow to earth through a shield wire installed along the tower and the impulse potential would be largely determined by the performance of the tower and earthing system. Whenever the potential exceeds the insulation strength, a backflashover (BFO) will take place along the insulator string [9][10][11][12]. Transmission system outage due to BFO is measured by the backflashover rate (BFR) and this will also reflect its performance [13].…”