Recovery Under Load Performance of 2nd Generation HTS Superconducting Fault Current Limiter for Electric Power Transmission Lines

Development of superconducting fault current limiters (SFCLs) has been pursued for decades and has been limited thermally and/or mechanically by the available superconducting materials performance characteristics . However, within the past few years a newer, more robust type of superconductor known as 2G HTS wire, has become available in sufficient quantity and lengths for developers to build prototype devices and test their capabilities. This new material has re-invigorated the worldwide race to develop a successful SFCL device that will meet the stringent demands of the electric utility application. SuperPower is pursuing the development of an electric power transmission line SFCL based on its proprietary 2G HTS wire and SFCL technologies. This manuscript will discuss recovery under load (RUL) performance of a SFCL designed for the American Electric Power reclosure sequence, which is a standard for electric power transmission and distribution lines. We also discuss low and high power tests and the influence of the different variables that have an important impact in RUL. A wide operating RUL window has been tested in order to define where RUL is feasible.

I. Introduction

With the dramatically increased demand on electric power, new power generation is being added and the power delivery networks are being upgraded. The levels of fault currents from events such as lightning striking a power line, or downed trees or utility poles shorting the power lines to ground, can increase beyond the capabilities of the existing equipment, leaving circuit breakers in an “over-duty” condition. Fault-current limiters (FCL) using high temperature superconductors offer a solution to control fault-current levels on utility distribution and transmission networks [1]–[4] [5]. SuperPower, Inc. and its research partners, including American Electric Power (AEP), have been working on a three-phase program to develop a practical SFCL to meet the needs of the utilities.