II. Wissenschaftliche Vorträge

methods fbr storage, sensing and energy trading, which are discusscd briefly in the
fbllowing paragraphs.1
Storage is a major issue in the integration of renewable energy sources such
as solar and wind, as these sources are only available intermittently. The mecha-
nical inertia of large traditional power plants is a source of stability in the grid,
and a balance between generation and load can be maintained by Controlling the
Output of such plants. Wind and solar do not provide such inertia and thus, as
the penetration of such sources becomes more significant, new methods must be
developed to provide inertia and stability. The incorporation of large-scale energy
storage into the grid is needed to provide this stability, and also to assure that energy
is available when it is needed and not just when the sun shines or the wind blows.
Consequently, grid scale storage is an area of rapid technology development. One
promising solution for grid-scale storage is pumped hydro, which is a Variation on
more traditional hydroelectric generation, in which water is pumped uphill to a
reservoir when there is a surplus of electricity production, and then allowed to run
downhill to generate electricity when there is a deficit in production. Other poten-
tial Solutions include Systems based on capacitors or Chemical batteries, distributed
storage taking advantage of the storage capacity of electric vehicles, pumped air, etc.
However, in general the current capability to störe energy at grid scale is not where
it needs to be for a complete transition to renewables, and this is an ongoing area
of technological development.
A key aspect of improving the reliability of the grid is advanced measurement
and control. Traditionally, monitoring and control ofthe transmission grid has used
a System known as SCADA - supervisory control and data acquisition. However,
the rate at which SCADA generates data can make it difficult to get a clear picture
of what is happening in the grid, and recent years have seen the development of
new types of sensors that are being deployed in much greater numbers, providing a
much more refmed idea ofwhat is happening in the grid, and allowing much finer
control ofwhat is going on in the grid. This is an important advance as well. One of
the types of sensors that has been developed is the so-called phasor measurement
unit, or PMU, which samples at a much higher rate than SCADA and allows for
measurement not only of the voltages of electric signals at various points in the grid
but also of their phases. The basic idea is that, with such advanced sensing, we can
get a much better picture of what is going on in the grid in real time, which may
allow grid operators to take actions to avoid, for example, cascading failures going
forward when an outage or other disturbance Starts happening.

1 It should be noted that the “grid” is actually two networks - the transmission grid, which car-
ries electric power at very high voltages over long distances from generators to substations in
cities and towns, and the distribution grid, which carries electric power at lower voltages from
these substations to consumers.

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