Response of Power System Protective Relays to Solar and HEMP MHD-E3 GIC

Geomagnetically induced currents (GIC) in a power system are the result of variations in the earth's magnetosphere influenced by solar storms or, in the extreme case, the late-time magnetohydrodynamic (MHD-E3) component of a high-altitude nuclear detonation. These currents appear as a quasi-DC offset superimposed on the AC current waveform and are capable of driving power system transformers towards saturation. A three-phase transformer system with varying levels of DC injection has been constructed in order to create a scale version of these quasi-DC transient waveforms. These harmonic rich waveforms have been used to create tests for injection into protective relays. The relays under analysis include microprocessor, solid state, and electromechanical, representing applications including transformer, line and feeder protection.