Solar Storms and their Impact on Electrical Power Grid

Solar storms are the solar winds containing charged particles produced by the sun which can reach the earth. On reaching the earth these charged particles creates a magnetic fields which can interact with the earth's magnetic fields. At times these magnetic fields can able to produce massive low frequency induced currents (quasi DC currents or AC currents with a higher time period of several cycles) in transmission systems. These Geomagnetic Induced dc currents (GIC) will have the potential to damage the transformers, and other electrical equipment in power system which may lead to blackouts and heavy loss in revenue. In this article the impact of solar flares on electrical power grid is discussed

Solar Storms or Solar Flares:

Thermo-nuclear explosions on the Sun's surface leads to release of radiation and charged particles which travel at a speed of 4 million miles per hour and can reach earth's atmosphere. These solar storms or flares may cause damage to communication and navigation systems and at times damages electrical equipment in power system thereby causing blackouts in the system. However the occurrence of these events is very rare. Earlier these events occur in the years 1859, 1921, 2003 and in 2012. Some of the effects of solar storms are:

Effects of Solar Storms:

  • Damaging communication and navigation systems
  • Radiation hazard to astronaut
  • Damaging electrical equipment with Geomagnetic induced currents results in outages

Solar Storms and Impact on Electrical Grid:

Biggest concern of solar storm is the threat it can pose on electrical grid. As explained earlier solar storms induces Geomagnetic Induced DC currents in the transmission system results in driving the transformer core into saturation leading to damage of transformer. Solar storm has the power to damage large number of power transformers at a single time resulting complete outage and replacing the damaged with the new will take significant amount of time and economy.

The harmonic current induced by solar storms trips the capacitor banks and other stat-com devices. Harmonic current will also have significant impact on the generators

As the present day grid is more complex and these events may lead to cascade tripping. So Solar storms pose a serious risk for the operation of grid during such events

Solar Storm Events in 1989:

In 1989 Solar storm damages two 400kV transformers in UK causing power outage. In the same year due to geomagnetic storm 6 million consumers lost power in Canada for 9 hours. Due to solar storm geomagnetic induced currents induces large current in transmission system near Salem Nuclear Power Plant. This damages step up transformer of unit-1 but reactor does not trip. However the transformer was replaced costing huge money . Many times solar storms damages the communication satellites

Control Measures:

Solar storms travel slowly and takes significant time to reach earth. Hence it can be detected by sun watching satellites and during the period transformers can be taken off-line and can restore back. However this can cause partial outage to the consumers at the cost of saving the transformer

Sensors that can monitor the currents in the transformer for Geomagnetic Induced currents are available. Transmission system can be designed in such way to minimize the magnetic interactions. Transformers are provided with built in circuitry against these solar flares. However in the present day Transformer manufacturing companies least bother about the solar flares while designing the transformers. But the magnitude of threat that solar storms may pose cannot be neglected

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