IEEE Power & Energy Magazine - Grid Edge 2023 - 38

The German Energiewende is having significant
impacts on the overall power system infrastructure
and its operation.
One rather seldom but nevertheless severe event for highPV-penetration
systems will take place in March 2015. On
20 March, from 08:40 to 11:00 a.m. UTC, a solar eclipse
will influence solar irradiation across Europe. Opacity
could reach 80% in continental Europe and could have a
significant influence on PV feed-in, depending on the day's
weather conditions. On a sunny day, the resulting hourly
gradient for Europe could be on the order of 18 GW. This
eclipse will therefore represent a challenge for the operation
of the European electric power system. It will also provide a
brief glimpse into the future for all stakeholders, since such
power gradients could well occur on ordinary sunny days in
a future in which installed PV generation capacity has seen
large increases.
Summary
The German Energiewende is having significant impacts
on the overall power system infrastructure and its operation.
Many commonly known and standardized procedures
for power system operation, operational planning,
and augmentation have to be rethought in the context of
increasing RES penetration. This article highlighted some
key issues from a German perspective.
We showed that the market for PV storage systems is
just getting off the ground. The increasing margin between
electricity prices and the PV feed-in tariff is fostering the
investigation of additional technologies for increasing the
local consumption of locally produced electricity. But
many issues still need to be addressed, such as the benefits
of PV self-consumption for the local distribution system
and for the overall energy system. In an environment
with many different PV storage system characteristics and
technologies, standards and transparency are gaining in
importance and need to be focused on by norming institutions
to guarantee the smooth and reliable operation of the
system for end users as well as grid operators.
German DSOs, which are in charge of maintaining service
quality for their customers, must host the vast majority
of RES. Cost-intensive grid reinforcements are the
consequence. Several studies have revealed the economic
benefits from reactive power control by inverters, MV/
LV tap-changing transformers, and voltage sensitive and
coordinated active power curtailments. However, the last
approach requires changes in the regulatory design that are
under discussion. These solutions and the more linear than
exponential growth of PV systems allows new approaches
in distribution system planning in the future with a significant
cost saving potential. Also, further improvements of
grid codes are necessary to guarantee a secure system operation
for the future. This includes stability regulations not
only for frequency (see experiences in " What Has Become
of the German 50.2-Hz Issue? " ) but also for voltage disturbances,
e.g., low voltage ride through in low voltage grids
as well as a European-wide harmonized set of regulations
that are prepared by ENTSO-E for the European interconnected
system. In the future, DSOs may have to act as
Feed-In of PV Systems at 50Hertz-Overview (2013)
Maximum Feed-In
Minimal Feed-In
Highest Decrease Within 1/4 Hour
Highest Increase Within 1/4 Hour
Highest Difference Between
Minimum and Maximum Within One Day
(a)
PV Feed-In (01/06/2013-07/06/2013)
5,346 MW
0 WM
1,594 MW
752 MW
5,346 MW
1,000
2,000
3,000
4,000
5,000
Forecast
Extrapolated
Feed-In
024487296 120 144 168
Time (h)
(b)
High Requirements on Forecasts, Controlling Ability, and System Operation
figure 13. Volatile PV feed-in in the 50Hertz service area in 2013: (a) overview and (b) during one week in June 2013.
38
ieee power & energy magazine
march/april 2015
MW

IEEE Power & Energy Magazine - Grid Edge 2023

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