5.4 Description of the Optimization Approach
113
with t interrupt duration of the production interruption
t state
time for lingering in a machine state (warmup, standby)
If the production interruptions are long enough to talk about machine state
changes, the energy consumption during the different state combinations has to
be compared in the next step. A change of states is worthwhile only if the energy
consumption in the idle state is higher than the sum of the consumption of standby
and the fast warmup status in the same time period.
t interrupt × P idle >
t interrupt − t warmup
× P standby + t warmup × P warmup
(5.3)
with P state power consumption in a machine state (idle, warmup, standby)
If the time period t interrupt is long enough to bring the machine into a lowerenergy state for a fixed duration and the total energy consumption is lower than
in idle state, this results in potential energy savings during the non-value-adding
production times, which can be easily implemented (Figure 5.18).
In addition to the standby state, it is also possible to check whether it is more
energy-efficient to bring the machine in an off state and through the associated
normal warmup process. The normal machine warmup, which is required as soon
as the machine has been switched off completely, might be more energy intensive
than remaining in standby state, the energy consumptions for the different runtime
options need to be compared carefully. Thus, it can be checked for which production interruption length which variant has to be selected to realize optimization
potentials.
Besides the consequent optimization of machine states, peak load avoidance
offers further optimization potential. As described in section 3.3, the network
tariff component of the electricity tariff is calculated according to the maximum
consumption peaks that occur. The avoidance of power peaks therefore has a
direct influence on the guaranteed electric grid capacity and the network charge
calculation. To detect and avoid peak consumptions, all electricity consumers in
a production must be recorded with their individual consumption values. In addition, it is advantageous to identify non-critical machines that can be taken out of
service in case of an imminent peak consumption. Performance peaks can usually
be avoided already by a time-delayed scheduling of the main electricity consumers
(Figure 5.19).
113
with t interrupt duration of the production interruption
t state
time for lingering in a machine state (warmup, standby)
If the production interruptions are long enough to talk about machine state
changes, the energy consumption during the different state combinations has to
be compared in the next step. A change of states is worthwhile only if the energy
consumption in the idle state is higher than the sum of the consumption of standby
and the fast warmup status in the same time period.
t interrupt × P idle >
t interrupt − t warmup
× P standby + t warmup × P warmup
(5.3)
with P state power consumption in a machine state (idle, warmup, standby)
If the time period t interrupt is long enough to bring the machine into a lowerenergy state for a fixed duration and the total energy consumption is lower than
in idle state, this results in potential energy savings during the non-value-adding
production times, which can be easily implemented (Figure 5.18).
In addition to the standby state, it is also possible to check whether it is more
energy-efficient to bring the machine in an off state and through the associated
normal warmup process. The normal machine warmup, which is required as soon
as the machine has been switched off completely, might be more energy intensive
than remaining in standby state, the energy consumptions for the different runtime
options need to be compared carefully. Thus, it can be checked for which production interruption length which variant has to be selected to realize optimization
potentials.
Besides the consequent optimization of machine states, peak load avoidance
offers further optimization potential. As described in section 3.3, the network
tariff component of the electricity tariff is calculated according to the maximum
consumption peaks that occur. The avoidance of power peaks therefore has a
direct influence on the guaranteed electric grid capacity and the network charge
calculation. To detect and avoid peak consumptions, all electricity consumers in
a production must be recorded with their individual consumption values. In addition, it is advantageous to identify non-critical machines that can be taken out of
service in case of an imminent peak consumption. Performance peaks can usually
be avoided already by a time-delayed scheduling of the main electricity consumers
(Figure 5.19).