Improving the reliability of breaker-and-a-half substations using sectionalized busbars

In utility power system substation design, the breaker-and-a-half topology is frequently used, primarily because it is considered very reliable. This paper aims to demonstrate that by adding sectionalizing circuit breakers into the busbars of the breaker-and-a-half configuration, the reliability of this substation design can be improved. Using a combinatorics-based approach to combining reliability indices of substation component failures, combined with using minimal cut sets of reliability graphs to identify failure scenarios, overall system failure rates were calculated for various substation topologies. The results demonstrate that the sectionalized breaker-and-a-half topology reduces the substation´s failure rate by 70.8% and its total annual downtime by 28.9% compared to a typical breaker-and-a-half scheme, although at the cost of increasing the mean time to repair of a substation failure by 2.49 hours.