IEEE Power & Energy Magazine - Grid Edge 2023 - 36

40,000
35,000
30,000
25,000
20,000
15,000
10,000
5,000
Current
Situation
37,380
Forecast
32,650
Installed Capacity Late 2013*
Wind
Photovoltaics
Biomass
Others
Total
13,408 MW
7,435 MW
1,646 MW
238 MW
22,727 MW
26,530
Others
Biomass
Wind Onshore
Wind Offshore
Photovoltaics
15,130
8,100
2000
2,100
2005
2010
*Source: www.netztransparenz.de
As of 31/12/2013
2013 EEG Mid-Term Forecast Scenario " Trend "
figure 11. Generation capacity based on renewable energy sources: the present situation and forecast capacities for the
50Hertz service area (sources: 50Hertz Transmission GmbH and www.netztransparenz.de).
and transmission grids (in Germany, 220/110-kV and
380/110-kV substations) has become an especially important
question, since most of the controllable distributed generation
is connected to the distribution grid. Such " active and
reactive power on demand " approaches could support the
traditional redispatch and voltage-control schemes used by
TSOs through the coordinated control of distributed generators.
Once implemented, this would represent a considerable
step toward the more active participation of distributed generators
in overall power system operation.
PV Systems' Impact on
the Transmission System
As stated in the introduction of this article, PV systems are
already the major source of electricity (in terms of capacity) in
Germany. Under favorable weather conditions, PV systems are
able to completely cover Germany's noon peak load, as depicted
in Figure 9 (that is, during the typically sunny but relatively cold
days of spring). PV systems are not the only significant weatherdependent
source of electricity within the German power system,
however. Together, PV systems and wind are able to cover
more than half of the German noon peak load, if high solar irradiation
occurs simultaneously with windy weather conditions
(see the Saturday and Sunday portions in Figure 9). It is on those
days that German base-load power plants have to be powered
down to maintain power system stability.
The company 50Hertz Transmission GmbH is one of the
four German TSOs and is responsible for the northeastern
36
ieee power & energy magazine
part of Germany and Hamburg. Its service area covers more
than 18 million end consumers, who are currently serviced
by more than 900 employees. Its tasks include the coordination
of system operation, operational planning and maintenance
work, long-term grid planning, and the augmentation
of a total of 10,000 km of 220-kV and 380-kV transmission
lines. Figure 10 shows the 50Hertz service area and provides
a schematic of its grid layout.
The German Energiewende or " energy transition " has
gained noticeably in pace and importance during the last
few years. Volatile RES already cover 37% of the total load
consumption in the 50Hertz control area, making this region
the worldwide leader (see Figures 11 and 12).
A securely operated and therefore reliable extra-highvoltage
grid is one precondition for guaranteeing the security
of supply and enabling further deployment of RES.
Alongside voltage and congestion issues, one of the major
operational challenges for TSOs relates to increasing power
gradients due to the high volatility of wind and PV feed-in.
These gradients can reach values above 1,500 MW in the
course of 15 min, as has already been recorded within the
50Hertz service area, as shown in Figure 13(a). Balancing
generation and load at a frequency of 50 Hz can be quite a
challenge during these events. When one takes into account
forecasts of RES generation capacity, it is obvious that such
remarkable power gradients will become even more frequent
in the future. Accordingly, the need for controllable power to
balance out the power system frequency is going to increase.
march/april 2015
2015
2020
2025

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IEEE Power & Energy Magazine - Grid Edge 2023

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