Some ~3000 HVAC Phase Inverters are needed in North America to cope with Geomagnetically induced currents from magnetic storms


In the global High Voltage Transmission trade, Phase Inverters are modified circuit systems designed to break off contact with the source of the abnormal
Ergo, Phase Inverters are key to islanding a mains AC or DC transmission system when transmission line conditions are exceeded.

What is the effect of a geomagnetic storm on a HVAC transmission system?

HVAC : Geomagnetically induced currents = unsustainable DC bias levels.
HVDC : Geomagnetically induced currents = random "AC like" bias levels.

HVAC or HVDC, geomagnetically induced currents are a problem. HVAC however dominates the North American mains power networks, with about 98% of all 250kv+ routes being HVAC. Ergo, the solution must primarily address HVAC's problems.

HVAC : Geomagnetically induced currents = unsustainable DC bias levels.

Yes, geomagnetic storms are that simple. DC bias sensing circuits generally must be omnipresent in any HVAC transmission system to work at all. However, mostly DC bias sensing is not coupled with phase inverter islanding.

DC bias sensing must be coupled with phase inverter islanding, and it must be a universal feature of mains power systems that are anywhere near the North Pole or Arctic Circle.

DC bias behaviours

DC bias can and does vary in magnetic storms, but at very low frequencies like 1 Hz to 2 Hz. Often the DC bias during a geomagnetic storm may be 0.5 hz. The frequency of DC bias variation itself is not the problem, it is the large induced DC currents that the HVAC transmission system must cope with -- and generally for witch it is not designed to handle.

The Phase Inverter Granularity Solution

The more phase inverters the are placed at the borders of a HVAC transmission system, the more capable the system is with respect to self islanding during geomagnetic storm events.

General principals



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Max Power

15 November 2011

09 May 2013

22 July 2013

22 July 2013, cleanup