Design considerations and experimental results for a 12.47-kV 3-phase 1 MVA power router

The increasing load, increasing level of penetration of renewable energy and limited investment in transmission infrastructure have significantly increased the need for a smart, dynamically controllable grid. This paper proposes a power flow control device to maximize asset utilization, improve reliability, and reduce congestion. To ensure low cost of implementation and high reliability, the technology is based on a system with fractionally-rated electronics paired with a line-frequency transformer built using standard materials and processes as utility-grade transformers. The proposed “power router” is realized by augmenting a three-phase utility-grade transformer with three fractionally-rated direct AC converters. The paper will address key design challenges associated with utility-grade equipment that include requirement for high reliability and availability, long life in excess of 20 years with limited or no maintenance schedule, rugged and often harsh operating environment, high BIL ratings and high fault-handling capabilities. The paper will discuss design and development of a 12.47 kV, 1 MVA three-phase system with these challenges taken into account and conclude with experimental results.