Ingenieur Vol. 75 ingenieur July 2018-FA | Page 49

Figure 4: The impacts of variable generation on the flexibility time line.
Figure 5: The Balancing Mechanism between Variability and Flexibility
As mentioned earlier, with the anticipated
large-scale integration of solar renewable variable
generation in the electricity infrastructure grid
network, future power systems will need to have a
higher level of flexibility which requires challenging
MW ramping rates in the operational time frame,
and characterising these ramping rates within
the planning domain is becoming increasingly
necessary. Operational flexibility is related to
the system’s ability to deal with variability within
system operation time scales - normally from a day
ahead down to real time. The type of operational
flexibility required will depend on the time scale:
• Increased frequency response and reserves
from seconds to minutes;
• Increased ramping capability from minutes
to hours; and
• Scheduling flexibility from hours to a day
ahead.
The time scales of flexibility, from the system-
planning perspective down to very short-term
operation, and the impacts of variable generation
on flexibility can be seen in Figure 4.
Figure 5 depicts how each part of the system
affects the need for and supply of flexibility. The
variability sources drive the need for flexibility to
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