Modeling Geomagnetic Interference on Railway Signaling Track Circuits

Abstract

Misoperation of railway signaling during geomagnetic disturbances has occurred in a number of countries. Railway signals are activated by track circuits that detect the presence of a train in a particular rail section, but geomagnetically induced electric fields can interfere with the track circuit operation, causing the wrong signal to be displayed. This paper develops a new model for track circuit operation that includes the induced geoelectric fields produced by geomagnetic field variations. Rails are modeled as transmission lines with series impedance given by the rail resistance and parallel admittance determined by the current leakage from the rail through the ballast to ground. The transmission line model is then converted into an equivalent‐pi circuit for each rail and these are combined with the track circuit power and relay components to form a nodal admittance network for the track circuit. This is used to examine the effect of induced geoelectric fields on track circuit operation. First, an individual track circuit is examined and it is shown how the length, between insulating rail joints, of the individual rails influences the geomagnetic interference voltage produced across the track circuit relay. Then a series of track circuits is considered: A general solution is developed and then the conditions are identified that allow this to be reduced to a simpler solution considering each track circuit individually. This modeling provides insight into the conditions that produce signaling problems and provides the tools to assess the geomagnetic hazard to railway signaling.

New Detailed Modeling of GICs in the Spanish Power Transmission Grid

“…Because the GICs are strong quasi-direct currents (DC) flowing in response to the geoelectric field, they may disrupt or permanently damage these transformers. These currents are responsible for both dramatic system-level failures, such as the famous Hydro-Québec 1989 outage that affected millions of people, and less severe but far more frequent effects such as pipeline corrosion (Gummow et al, 2002;Pulkkinen et al, 2001), railway support system failures (Boteler, 2021) and power transformer wear. Although traditionally viewed as a high-latitude phenomenon, during the Halloween storms of 2003 reports indicated important GIC impacts in South Africa (Gaunt and Coetzee, 2007), where geomagnetic latitudes range between 25° S and 35° S. After those reports and our first analysis in north-eastern Spain (Torta et al, 2012), vulnerability assessments of the GIC hazards in midto-low latitude countries have proliferated all over the world.…”

“…The geoelectric fields interact with ground‐based infrastructures and generate geomagnetically induced currents (GICs), which are electrical currents induced in conductors that operate on the Earth's surface (Boteler & Pirjola, 2017; Pulkkinen et al., 2017). Large infrastructures as electric‐power transmission grids, oil and gas pipelines and even railway signaling track circuits (Boteler, 2021) are commonly affected negatively by GICs. These can potentially cause problems such as damaged power transformers and/or increased corrosion of pipeline steel, which in turn may have an impact on the critical infrastructures that provide services to the population such as electric power, gas or oil delivery and train systems.…”

“…These currents are responsible for both dramatic system‐level failures, such as the famous Hydro‐Québec 1989 outage that affected millions of people, and less severe but far more frequent effects such as pipeline corrosion (Gummow & Eng, 2002; Pulkkinen et al., 2001), railway support system failures (Boteler, 2021) and power transformer wear. Although traditionally viewed as a high‐latitude phenomenon, during the Halloween storms of 2003 reports indicated important GIC impacts in South Africa (Gaunt & Coetzee, 2007), where geomagnetic latitudes range between 25°S and 35°S.…”

Adaptations to a geomagnetic field interpolation method in Southern Africa

“…Loosely, space weather is the effect of solar activity on the Earth and the near-Earth environment. The technologies affected by adverse space weather are widespread, ranging from satellite operation, HF communication and GPS navigation, to grounded conducting networks such as power grids, railways and pipelines (Boteler et al, 1998;Kelbert, 2020;Boteler, 2021). The primary space weather related cause of damage in power grids and pipelines arises from geomagnetically induced currents (GICs).…”

Climatological Statistics of Extreme Geomagnetic Fluctuations With Periods From 1 s to 60 min

“…Large electrical currents are occasionally induced in ground‐based infrastructure as a result of rare and intense currents in the ionosphere or magnetosphere. These geomagnetically induced currents (GICs) have been identified as a substantial hazard to national infrastructure (Cannon et al., 2013; Hapgood et al., 2021) since they may cause catastrophic failure in high‐voltage (HV) electricity supply networks (Gaunt, 2016; Oyedokun & Cilliers, 2018; Thomson et al., 2010), damage long‐cable communication systems (Nevanlinna et al., 2001), and cause railway signaling errors (Boteler, 2021; Eroshenko et al., 2010; Wik et al., 2009). The cumulative effect of GICs above a certain threshold may also cause corrosion in oil and gas pipelines (Boteler, 2000; Pulkkinen et al., 2001).…”