Low frequency currents (GIC) in electrical power systems

Motivated by an unexpectedly high noise level of some of the transformers in the 2014 substation, investigations on very low frequency neutral point currents, especially geomagnetically induced currents (GIC), in the Austrian power transmission grid were carried out.

First measurements showed an increased transformer neutral point current. For the area-wide analysis of the neutral point currents, a direct current measuring system for transformer neutral point was developed and installed at five transformers in the Austrian transmission grid.

Fig. 1: Measurement installations in the Austrian power transmission grid

In parallel, the geomagnetically induced current in the transmission grid was calculated from the measured magnetic field changes and correlated with the measured data. Furthermore, the measurements also show frequency components that can be attributed to human influence.

Fig. 2: Correlated Earth magnetic field and the measured transformer neutral point current


Halbedl, T.
Low Frequency Neutral Point Currents on Transformer in the Austrian power Transmission Network
PhD Thesis, Graz, Austria, 2019

Bailey, R. L.; Achleitner, G.; Halbedl, T.; Leonhardt, R.
Geomagnetically Induced Currents in Austria
In: EnInnov, Graz, Austria, 2018, Conference Presentation

Halbedl, T.; Renner, H.; Achleitner, G.
Geomagnetically induced currents modelling and monitoring transformer neutral currents in Austria
In: e&i, 2018

Bailey, R. L.; Halbedl, T.; Schattauer, I.; Achleitner, G.; Leonhardt, R.
Validating GIC Models With Measurements in Austria: Evaluation of Accuracy and Sensitivity to Input Parameters
In: Space Weather, 16, 887–902, 2018, DOI: 10.1029/2018SW001842

Bailey, R. L.; Halbedl, T.; Schattauer, Ingrid; Römer, Alexander; Achleitner, G.; Beggan, C. D.; Wesztergom, Viktor; Egli, Ramon; Leonhardt, R.
Modelling geomagnetically induced currents in midlatitude Central Europe using a thin-sheet approach
In: Ann. Geophys., 35, 751-761, 2017, Journal Paper, DOI: 10.5194/angeo-35-751-2017

Halbedl, T.; Renner, H.; Bailey, R. L.; Leonhardt, R.; Achleitner, G.
Analysis of the impact of geomagnetic disturbances on the Austrian transmission grid
In: 19th Power Systems Computation Conference 2016, Genoa, Italy, 20th-24th June 2016, Conference Paper, DOI: 10.1109/PSCC.2016.7540833

Halbedl, T.; Renner, H.; Sakulin, M.; Achleitner, G.
Measurement and analysis of neutral point currents in a 400-kV-network
In: 2014 Electric Power Quality and Supply Reliability Conference (PQ), Rakvere, Estonia, 11th-13th June 2014, Conference Paper, DOI: 10.1109/PQ.2014.6866785

Halbedl, T.,
Messung von Gleichströmen am Sternpunkt von Drehstromtransformatoren im Höchstspannungsnetz
Master Thesis, Graz University of Technology, Graz, Austria, 2014

Project Information


Prof. Herwig Renner


  • Duration: November 2014 – December 2017
  • Coordinator: Prof. Herwig Renner
  • Staff: Thomas Halbedl


  • Austrian Power Grid