GIC Analysis using PSS®E Siemens Power Technologies International GIC Analysis using PSS®E

NERC TPL-007-1 Title: Transmission System Planned Performance for Geomagnetic Disturbance Events Purpose: Establish requirements for Transmission system planned performance during geomagnetic disturbance (GMD) events. Applicable to: Planning Coordinator Transmission Planner Transmission Owner Generator Owner with Facilities that include power transformer(s) with a high side, wye-grounded winding with terminal voltage greater than 200 kV.

NERC TPL-007-1 GMD Vulnerability Assessment Process PSS®E GIC Module PSS®E Analysis: Contingency QV PV

GMD Event Uniform Geoelectric Field E(t) Ignores effects of local earth conductivity and local geomagnetic latitude Non-uniform Geoelectric Field E(t) Considers 1-D local earth conductivity models Benchmark GMD Event E(t) E = 8 V/km Considers α, the scaling factor to account for local geomagnetic latitude, and β, the scaling factor to account for the local earth conductivity structure

Development of DC System Model Power flow network data reduced to just resistance network with these modifications: The transmission lines modeled as resistor in series with induced voltage. Line reactors / charging ignored. Grounded two- and three-winding transformers modeled with their winding resistance to ground. Grounded auto-transformers are modeled with their common and series winding resistance. Grounded Bus shunts are modeled. Equivalent station grounding resistance is modeled.

Required GIC Data GIC Data File Data not found in PSS®E network files is provided in an external data file, *.gic PSS®E provides template to create such a .gic data file for desired subsystem of the network

Required GIC Data Substations

Required GIC Data Transformers

Required GIC Data Shunts and Branches

Required GIC Data 1-D Earth Conductivity Model

How to run GIC Analysis in PSS®E?

PSS®E GIC Analysis Input and Output Options Text Report GMD Storm Sub System Data Defaults GIC Data Calculation Options Output Files Electrojet Chars.

PSS®E GIC Calculations GMD Storm Scenario PSS®E GIC Module PSS®E GIC Data PSS®E Power Flow Network GICs, Transformer Q Losses PSS®E Power Flow Network with GIC Losses AC Power flow studies Contingency analysis PV/QV analysis Dynamic analysis

Contingency Analysis with Benchmark Event GMD Effect of Geoelectric Field Direction

Contingency Analysis with Uniform Field GMD Effect of Geoelectric Field Magnitude

QV Analysis with GMD

Bus Voltages with GMD

Substation and Branch GICs

PSS®E GIC Module Conclusion Fully integrated in PSS®E Uses standard PSS®E networks (.sav or .raw files) No Sequence data required Additional data required for GIC calculations supplied through external GIC data file GIC data files can be prepared using interactive tools, GIC Python module and Excel or a text editor Rich reporting and interactive diagrams Present GIC results on Network maps

GMD Vulnerability Assessment Conclusion The conversion of GIC flows in a transformer to reactive power losses is crucial to ascertain and quantify GMD effects on power system performance. It is important to note that having accurate K factors from transformer tests and specifications will determine the accuracy of these studies. The earth conductivity models play a deterministic role in evaluating the GIC flow in the network. For conservative power system performance evaluation under GMD events, it is necessary to determine the geo-electric field orientation that would result in maximum reactive power losses in transformers.

Thank you for your attention! Krishnat Patil Senior Staff Engineer Siemens Industry, Inc. Siemens Power Technologies International 400 State Street Schenectady, NY 12305 Phone: +1 (518) 395 5081 E-mail: krishnat.patil@siemens.com