Power Grid Sensitivity Analysis of Geomagnetically Induced Currents

Abstract

Geomagnetically induced currents (GICs) have the potential to severely disrupt power grid operations, and hence their impact needs to be assessed through planning studies. This paper presents a methodology for determining the sensitivity of the GICs calculated for individual and/or groups of transformers to the assumed quasi-dc electric fields on the transmission lines that induce the GICs. Example calculations are provided for two small systems and for the North American Eastern Interconnect model. Results indicate that transformer GICs are mostly due to the electric fields on nearby transmission lines, implying localized electric field models may be appropriate for such studies.

Blocking Device Placement for Mitigating the Effects of Geomagnetically Induced Currents

“…The E-field induces (quasi-)dc voltages in the transmission lines, with GICs induced across the whole network and grounded through substation transformers. Hence, the GIC flow model is based on a dc network analysis for all the buses and substations; see e.g., [11], [15].…”

“…The GIC flow between any two connected nodes can be computed by [11] (6) which is also different from the Norton equivalent current injection in (3).…”

“…The QLoss at any transformer can be assumed to be linear in its effective GIC [11], as defined by (7) where and denote the per-phase transformer GIC flows, and is the transformer turns ratio. Specifically, as shown in Fig.…”

“…Different from the three-phase GIC , the per-phase and need to be computed using the per-phase equivalent by substituting the conductance with in (6). Upon obtaining , the QLoss due to the transformer saturation in MVAR becomes [1], [11], [12] (8)…”

“…where the parameter can be found based on transformer characteristics and per unit bus voltage as detailed in [11].…”