US 7,489,485 B2
	Method and equipment for the protection of power systems against geomagnetically induced currents
Mats A F Klercker Alakula, Kavlinge (Sweden); and Sture Lindhal, Lund (Sweden)
Assigned to Forskarpatent I Syd AB, Lund (Sweden)
Filed on Nov. 07, 2006, as Appl. No. 11/557,330.
Application 11/557330 is a continuation of application No. PCT/SE2005/000659, filed on May 04, 2005.
Claims priority of application No. 0401193 (SE), filed on May 10, 2004.
Prior Publication US 2007/0217103 A1, Sep. 20, 2007
Int. Cl. H02H 7/04 (2006.01)

U.S. Cl. 361—35

5 Claims

1. A method for protection of power transformers and other power system components, which are vulnerable to geomagnetically induced currents, which comprises feeding a DC-diverter from at least one of an overhead line or a cable conductor connected to the power transformers, said DC-diverter consisting of primary diverter windings and compensation windings applied on a respective magnetic core leg, which at least one DC-diverter is connected to critical busses, and diverting “quasi” direct current flowing on the at least one of an overhead line or a cable conductor as a result of earth surface potential gradients caused by geomagnetically induced currents, wherein said DC-inverter comprises a magnetic core structure having three phase legs, each leg provided with a primary diverter winding and each provided with a diverter compensation winding having a filter connected to the neutral point of the three-phase diverter to reduce harmonics, to eliminate flow of these through the compensation winding, and whereby the diverter has an impedance lower than that of a component diverted from.