Geomagnetic Storms Could Blow Away the Power Grid: Fixes are Possible When And If We Get Concerned Enough

Are solar storms another ‘the sky is falling’ scare? Or do we need to take action, and soon?

“The industry only changes following a big crisis and we’re about due for another one.” That was a remark made at a recent meeting of utility industry experts. I believe it.

It took the 12 hour Northeast blackout of 1965, which knocked out power to 30 million customers, to get us seriously working on coordinated, interstate transmission standards. The result was the formation of the North American Reliability Council (NERC) in 1968. We can also thank the disaster for pushing the development of transmission SCADA and programmable relays. There have been other less spectacular area-wide transmission outages since then (particularly in the Northeast for some reason). These have also resulted in major (overdue) operating changes.

Waiting for disasters to occur in order to take action may save a few bucks, but sometimes the potential risk is so high you can’t afford to let happenstance happen. You don’t want to check for a possible retinal aneurism by continuing to lift weights at the gym!

When we discuss grid security we usually are thinking ‘cyber-security’. But the power system is far more vulnerable to other types of attacks, such as physical destruction of critical system components. These mostly go ignored. (see Cyber-threat or Cyber-hype?)

Then there’s the 800 pound-gorilla-sleeping-in-the-closet threat: a geomagnetic storm which, if big enough, could shut down the world’s power grids so destructively that they would be out for weeks, possibly months.

Our sun produces ‘solar winds’ of charged particles that can reach the earth. In turn, these streams of particles create magnetic fields that interfere with the earth’s magnetic fields. If the solar winds flare up large enough, the resulting magnetic fields can produce massive, low frequency currents in transmission networks. This, in turn, can easily destroy $10 million high voltage transformers which, in the case of widespread damage, would take weeks or months to replace.

The effects of these Geomagnetic Induced Currents (GIC) are similar to those of an Electromagnetic Pulse (EMP) generated by the detonation of a nuclear bomb. So it figures that there has been plenty of spending on research related to potential impacts of both GIC and EMP on the government and civilian power systems.

The findings? We could be in a heap of trouble if a large, or even moderate geomagnetic storm occurs.

Fortunately they don’t happen often. The last big one was in 1921, before anyone had miles of large scale transmission (the bigger the transmission ‘loop’ the bigger the effect). Then in 1989 we had another geomagnetic storm. This time 6 million customers in Quebec lost power for 9 hours. Not a world-scale calamity, but on the other hand, the 1989 storm has been estimated to be about one-tenth the strength of those that have hit the earth in the past. It was a much larger storm in 1859 that started scientists looking at the phenomenon in the first place. That’s frighteningly recent!

We are in the middle of a solar flare-up that started in January 2009 and is expected to peak in May 2013. Whether this is ‘the big one’ depends on the storm orientation, intensity and duration. Hopefully we’ll make it through okay. But who knows?

So what are we doing about the potential threat of GIC? Not much. I have to admit that I’ve always been skeptical of the potential for any real damage. It seemed to me like it’s just another of the ‘sky is falling’ alarms that go off every few years and then disappear. Now I’m not so sure we should go on ignoring it.

What can we do? Transmission operators already have sensors to monitor transformer currents for GIC effects but no one is seriously planning to make the system radically less vulnerable. There are ways to structurally design the high voltage system to minimize the magnetic interactions. Transformers can have built-in protection circuitry. But at present no utility or agency is going to retrofit or rebuild the grid infrastructure to protect against GIC, and therefore there’ll be no market for new GIC-safe transformer design until we have a crisis. A big part of the seeming complacency is that the biggest threat is to long-mileage interstate transmission where no one utility or other entity is fully responsible. NERC is the watchdog. But NERC is only recommending emergency response procedures and publishing GIC threat assessments.

This complacency could change as we consider looking at a bigger picture of ‘smart grid’. Or even ‘micro-grids’, because when it comes to GIC, smaller/local is better. As we move towards what some call Grid Optimization, why not consider making the system bulletproof against GIC?

For more reading on the topic, check out A Perfect Storm of Planetary Proportions in the March, 2012 issue of the IEEE Spectrum.





GIC Preperation

The notion that utilities are ignoring the threat of GIC is patently false. This misinformation continues to be spread by consultants that have a financial interest in pushing a false premise. Utilities have been actively engaged in GIC mitigation and operating strategy. The article published in IEEE spectrum on GIC is based on a biased point of view. There is an overwhelming amount of speculation in this article. The focus of the NERC task team and the IEEE spectrum article focus on transformer issue and not the most probable problem. As engineers we constantly design to a set of conditions or probabilities. It is more probable that a GIC storm will cause a wide spread outage due to a voltage collapse. The 1989 Hydro Quebec outage was a great example of this point. The outage occurred from Var consumption of overexcited transformers and the harmonics that were generated. The capacitor banks protection schemes miss operated and SVC’s tripped due to harmonics overloading filter banks. The lack of Vars and voltage support caused the power system in Hydro Quebec to collapse. Outages were not cussed by wide spread transformer failures.
Since the 1989 event utilities in the north east have been diligently hardening there infrastructure. Utilities are using asset management as a tool to replace equipment and develop a GIC resistant power system. The IEEE Transformers committee has had several forums and tutorials on transformer design changes to tolerate GIC. As aging infrastructure is replaced, new GIC resistant transformers are being installed. NERC did not force a solution looking for a problem because NERC actively sees utilities working on hardening the infrastructure. This fact is never conveyed by consultants since it does not meet business interest to do so. Capacitor bank designs that tolerate GIC are being installed as capacitor bank infrastructure is being replaced.
The notion that all GIC problems can be rectified by a DC blocking filter is full of complications and dangers. In all engineering endeavors you do not get anything for free. When you make an engineering change to solve one problem you get another problem. A DC blocking device in the neutral connection of a transformer is just such a thing. The device mentioned in the IEEE spectrum article is not a new concept or immune to the difficulties of any high speed bypass device. The speed of operation is not the determining factor. This device is a triggered device and must rely on speed of detection and triggering. This analogy is the same for all series capacitors. The installation of a DC blocking device in the neutral of a multimillion dollar transformer is neither easy nor trivial. The DC filter can cause a transformer failure for a handful of design parameters that effect operation for the other 99% of the time. The IEEE capacitor subcommittee is addressing the issue to develop standards and guidance on the design and application of DC blocking devices. The IEEE and NERC are working on GIC transmission modeling to be able to study the problem and develop a proper solution. The most disturbing part of the strategy above is that it appears more like a solution looking for a problem. This type of approach does not pass the smell test. Putting a DC blocking device in the neutral of a transformer is a lot like spraying for bugs. You spray the whole apartment building or the bugs move next door. I know I am ranting a little but what I am trying to say is that the utility industry is making changes for GIC because it is good business. Has the problem been completely solved no but the impression that utilities are not working on protecting the system is not accurate.