Saturday, May 2, 2015

Could a Power Outage of an Airplane happen in the Air?

Yes, a power outage of an modern airplane could be caused by a simple software problem – related likely to a wrong assumption. What does this mean for the future power systems?

The following official report from the U.S. Government FAA, dated May 01, 2015 says that a

Boeing Model 787 airplane that has been powered continuously for 248 days can lose all alternating current (AC) electrical power due to the generator control units (GCUs) simultaneously going into failsafe mode. This condition is caused by a software counter internal to the GCUs that will overflow after 248 days of continuous power.

The software counter internal to the generator control units (GCUs) will overflow after 248 days of continuous power, causing that GCU to go into failsafe mode. If the four main GCUs (associated with the engine mounted generators) were powered up at the same time, after 248 days of continuous power, all four GCUs will go into failsafe mode at the same time, resulting in a loss of all AC electrical power regardless of flight phase.”

Click HERE for the full report.

What is the lesson we can learn from this situation? I guess simply this: If you have to program something you need to know precisely under which assumptions the “something” should work. Usually you have to make firm assumption under which the “something” will work. If you would assume (for example) that an airplane of model 787 would never be powered continuously longer than 90 days, then the counter would not overflow under normal conditions.

But: If this assumption is wrong, then the counter could overflow.

I guess that we quite often design systems under assumptions that may be valid at time of the design – but that may show later that they were quite wrong! Some 40-50 years ago it was not assumed that the traffic in 2015 would be as is is now. Or?

The power utilities assumed some 15 years ago that PV-Power (mainly installed on roofs) should just be understood and treated as negative power connected to the grid – so that there was no need to invest in power management and automation systems. I remember such discussions in the German national standardization (DKE). Within a short time period they had to learn that the assumption was wrong! Now we have almost 40 GW of installed PV systems.

The next wrong assumption could likely be the number of Batteries connected to the power grid. The needed investment in the future power system will highly depend on the assumption on how fast the installation of batteries will happen! I have talked recently to utility experts that they fear a fast growth of network connected batteries. The batteries behave different compared to Wind Turbines and PV systems – batteries can import and export energy. They can change their behavior within very short time. A sudden huge power flow change of millions of battery systems could cause power outages.

So, MUST we assume that this could easily happens or not? Depending on our answer, we have do spent more or less Euros or Dollars … Experts that don’t want to invest a lot more will argue, that it is unlikely to happen.

The (wrong) assumptions of today could likely be the reasons of power outages in the near future. The bad side of the assumption that the installation of battery systems will grow fast is: It will require a lot of more efforts to keep the power system reliable.

I guess we will see increasing numbers of batteries being installed after yesterdays announcement (May 01, 2015) of the new Partnership for Global Energy Transformation: LichtBlick (Germany) integrates Tesla Battery Storage (US) into Energy Markets.

A crucial key component in the future power systems is related to information management and standardized information exchange with IEC 60870-5-104 and IEC 61850. VHPready is an important step to support LichtBlick and many other companies.

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