A feasibility study for a fault current limiter to reduce voltage sags at sensible loads

Abstract

In relatively weak electrical networks, that is, those with sparse interconnection between them; a fault occurring in any part of the network causes voltage sags to appear in different nodes, more severely in those adjacent to the fault. This occurs at every voltage level in an electrical network. Particularly so in distribution systems, when radial feeders originate from a same substation. In this case, a fault in one of the feeders will produce a voltage sag at the substation bus, thus affecting adjacent feeders. If any of these feeders supplies sensitive loads, like adjustable speed drives, PLC`S, computer systems, etc.; problems may arise at the customer loads where these voltage sags are seen as interruptions. It is suggested that a way to reduce these voltage sags to acceptable values can be achieved by limiting the fault current in the distribution feeders. A fault current limiter is defined as a series device that presents a low impedance to steady state currents, but acts quickly to limit the instantaneous magnitude of a fault current to a predetermined value. Many new fault current limiters (FCL) have been proposed lately in the literature but for this feasibility study a FCL of the LC resonantmore » link type was chosen for its simplicity.« less