atw 2018-04v6


atw Vol. 63 (2018) | Issue 4 ı April

Security of Supply ...

and the Clock is Ticking ...

Deal reader, More than one hundred years ago, around 1890, a conflict flared up between the two well-known

protagonists of electricity supply, Thomas Alva Edison and George Westinghouse, on the large-scale power supply and the

construction of power grids in the United States of America. While Edison technically preferred D.C. voltage, Westinghouse

counted instead on alternating voltage. In the end it was not a matter of the most suitable technique but of the anticipated

market shares of each company General Electric or Westinghouse Electric and the patents behind. At a breath taking pace,

the most important developments for the use of electricity were preceding: In the year 1866 Werner Von Siemens

discovered the dynamo- electrical principle, which enabled larger performance. The development of alternating voltage

in the year 1881 enabled generally technically and cost-effectively the transportation of electricity over long distances

– we are talking back then about distances of some ten kilometres. Alternating voltage enforced itself at that time due to

possible further transportation length enabled through higher trans mission voltage.



Both current types have something in common: generation

and use need to take place simultaneously. The grid fails if

both do not fit together. Neither alternating current grids

nor direct current grids offer storage possibilities. Thus, a

stable power system also requires a stable and reliable

generation, because if a larger system “fails”, the system

restoration is, from its task and process, a large-scale


Different believes e.g. from politics or other interest

groups are simply wrong, power systems are – without any

further active establishments and plants- no accumulators.

A reliable power supplying system needs at any time

reliable generation. “Surpluses”, meaning potentials for a

higher generation than demand, when so ever, cannot be

shifted or stored “electrically” in the system at a later time.

It was not an inconspicuous message, which appeared

multiple times in the press at the end of February,

beginning of March 2018. Headlines such as “Time

synchronisation per power system: Energy shortages make

watches lose time”, described a phenomenon, of which,

according to the media “one became aware of – only

( editor’s note) - after weeks”: What happened?

As an indicator for the stability of alternating power

systems stand supply voltage a well as system frequency.

For the system frequency applies that she needs to be

identical at any point of the system. If generation and

consumption do not fit, deviations occur, leaking generation

leads among others to a perceived frequency decrease

among the entire connected system. As the system

frequency is defined for our alternating electricity net with

constant 50 Hertz, it is also qualified for watches, which

use the frequency as direct clock indicator.

We can for example – due to cost reasons – renounce to

a frequency stabilising quartz oscillator. Nevertheless, this

technical simplification is bought with failures in time, if

the frequency deviates from the standard over a longer

period. Only a few hundred Hertz is enough for days and

weeks in order to, as in the current case, generate a time

deviation of minus 360 seconds, 6 minutes, and those

inside the entire affected system of 25 West, Middle- and

South European countries.

The cause for this incident was later communicated by

the European Network of Transmission System Operators for

Electricity (short ENTSO-E) and the Swiss net operator

swissgrid, that in the control zone Serbia, Macedonia,

Montenegro (the so called SMM rule block), especially in

Kosovo and Serbia less energy was fed into the system. A

deficit of 113 gigawatt hours was shown, not much, in view

of a European daily production of around 8,000 gigawatt

hours. But especially this shows how delicate our power

system is and how sensitive it reacts to the smallest


Reliable measures in power generation – meaning

currently only for conventional techniques, thus need,

with all considerations on the reconstruction of electricity

supply, to be reconsidered. Additionally and almost

simultaneously another alarming “availability message”

came in: At the beginning of March 2018 European gas

storage tanks were only filled with a quantity of 26.2 per

cent, Germany even on average only with 23.8 per cent.

Thus, according to an EU-conform proceeding an early

warning level was reached, because the filling level of

storage tanks may not be lower than around 20 % due to

reasons of guaranteeing mechanical stability. On top came

the message that more natural gas was imported to Europa

than in the previous years. All first hints, that there might

not be enough natural gas in Europe for dispose filling in as

a “reserve”?

In all, these are all important references that any,

especially neither direct market- nor technically driven,

interventions – where compensation factors can con tribute

– need to be well thought in our power system. Furthermore,

does the availability of a broad basis of conventional

generation not only gain more importance, she is even

more important than it is conceded for “conventionals”

vision wise in many places in terms of an „energy

transition“. To what extend “the clock” might tick on

possible severe supply shortfalls or even large-scale loss of

off-site power… one does not know…

Christopher Weßelmann

– Editor in Chief –


Security of Supply ... and the Clock is Ticking ...

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