5.4 Description of the Optimization Approach
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objective functions can be formulated to reduce the energy consumption in a production under the constraints that neither the height or the timing of outputs nor
the quality of the produced goods should be influenced negatively.
Firstly, the total energy consumption can be minimized by focusing on the
energy savings through minimizing non-value adding production times of machines. For the minimization, it needs to be checked if all machines are in an efficient
energy state regarding the current production task. The total energy consumption
can easily be reduced through the avoidance of unproductive machine states which
requires the exact definition of mandatory conditions and restrictions that have to
come with the objective functions (section 5.4.3)
Besides the total amount of the energy consumed, the guaranteed electrical grid
capacity provides a starting point for optimizations. Since only a few peak consumptions per year ensure that the guaranteed grid capacity is increased, and so
is the grid charge, consumption peaks exceeding the grid capacity should strictly
be avoided. Therefore, the energy consumption flow of the production should be
smaller than a defined maximum allowed peak value at any time. The maximum
allowed peak value is based on the guaranteed grid capacity minus a safety factor to generally avoid exceeding the grid capacity. Threatening load peaks can
be detected in advance by simulating production processes and thus precautionary measures can be initiated to avoid them. These precautions may include
re-scheduling of energy-intensive warm-up phases of individual machines as well
as, for example, the planned shutdown of ventilation and air-conditioning devices
in unoccupied or sparsely occupied sections of the production hall over short periods of time. The effect of rescheduling individual machines or entire production
lines to avoid peaks loads can be seen in the use cases in sections 5.6.4 and 6.3.
5.4.3 Optimization Parameters and Constraints
The optimization parameters are essential in order to create main control levers
with which the energy consumption behavior of the production machines can be
designed efficiently over the long term and under any load situation. Therefore,
it is indispensable to include adjustable and dynamic parameters and variables
for production processes and the production flow as well as planning parameters already when building the simulation model to be able to use them for
optimization runs.
Since the optimization parameters must be selected in a way that the optimization of the energy consumption is not to the detriment of the production output, it
117
objective functions can be formulated to reduce the energy consumption in a production under the constraints that neither the height or the timing of outputs nor
the quality of the produced goods should be influenced negatively.
Firstly, the total energy consumption can be minimized by focusing on the
energy savings through minimizing non-value adding production times of machines. For the minimization, it needs to be checked if all machines are in an efficient
energy state regarding the current production task. The total energy consumption
can easily be reduced through the avoidance of unproductive machine states which
requires the exact definition of mandatory conditions and restrictions that have to
come with the objective functions (section 5.4.3)
Besides the total amount of the energy consumed, the guaranteed electrical grid
capacity provides a starting point for optimizations. Since only a few peak consumptions per year ensure that the guaranteed grid capacity is increased, and so
is the grid charge, consumption peaks exceeding the grid capacity should strictly
be avoided. Therefore, the energy consumption flow of the production should be
smaller than a defined maximum allowed peak value at any time. The maximum
allowed peak value is based on the guaranteed grid capacity minus a safety factor to generally avoid exceeding the grid capacity. Threatening load peaks can
be detected in advance by simulating production processes and thus precautionary measures can be initiated to avoid them. These precautions may include
re-scheduling of energy-intensive warm-up phases of individual machines as well
as, for example, the planned shutdown of ventilation and air-conditioning devices
in unoccupied or sparsely occupied sections of the production hall over short periods of time. The effect of rescheduling individual machines or entire production
lines to avoid peaks loads can be seen in the use cases in sections 5.6.4 and 6.3.
5.4.3 Optimization Parameters and Constraints
The optimization parameters are essential in order to create main control levers
with which the energy consumption behavior of the production machines can be
designed efficiently over the long term and under any load situation. Therefore,
it is indispensable to include adjustable and dynamic parameters and variables
for production processes and the production flow as well as planning parameters already when building the simulation model to be able to use them for
optimization runs.
Since the optimization parameters must be selected in a way that the optimization of the energy consumption is not to the detriment of the production output, it