User Manual

Control concept
Superposed plant controls
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The upper part of the dialog box serves primarily to provide a quick online overview of the block. The
maximum power controlled by the block is set with the maximum power parameter [MaxPwr]. The value
must be greater than 0 kW in order for the block to work. Any changes in this limit value have a direct effect
in online mode. If no limit value is required, the maximum power must be set at an appropriately high value.
The Aggregates tab is used to set the control variables of the aggregates (boiler, refrigeration machine).
● Enable: Activation/deactivation of an entry if they are not released, aggregates in the Profile table will
be ignored.
● Command object reference: Reference (relative addressing) to multistate value blocks [MVAL] of the
relevant energy producer. During the configuration process, all MVAL blocks at the same and at lower
hierarchical levels are displayed.
● Aggregate description: The reference to the value object provides access to (and hence, knowledge of)
all information in a special dialog box via the referenced object in the control command.
● Switch-on delay: Delay time when switching from OFF to Stage 1.
● Switch-off delay: Delay time when switching from Stage n to OFF.
● Step-up delay: Delay time when switching from Stage n up to Stage n+1.
● Step-down delay: Delay time when switching down from Stage n to Stage n–1.
● Switch-on stage power: Power in [kW] at the lowest (that is, first) stage.
● Next power stage: Additional power at the next stage(s) in [kW].
The control sequences for the aggregates (boiler, refrigeration machine) are defined under the Aggregates
tab. Each profile describes the order in which the energy producers are to be switched and the maximum
stage in each case. A total of 8 profiles each with 15 sequence entries can be defined.
The active profile table is defined by entering the profile number [PrfNr] as an input parameter, or by
selecting it from the Profile dropdown list in the Plant Control Editor. This input parameter can be
interconnected, so that the profile can be changed as a function of other events (faults, summer mode,
boiler operating hours, etc.). If the profile is changed during operation, the power output [PrPwr] is
switched in accordance with the power profile in the new profile table.
The profile definition determines the order in which individual aggregates are to be switched on or off. The
following information must be entered for every sequence entry:
● Object: Selected from the previously referenced aggregates.
● Stage limitation: Limit up to which the aggregate may be enabled.
● Control type: Specifies whether the enabled stages are to be switched permanently or released to the
control system.
– Fixed: The total power provided by a given switch stage is switched on or off permanently. This
option can be used, e.g., for a specific base load which is required to be present at all times. The
command is implemented with Priority 14.
– Enable: The power actually required from the released switch stage is determined by local control of
the aggregates. The command is implemented with Priority 16.
For each sequence step, the function block only ever releases the last aggregate marked Release to the
control system. It displays this released object [RlsObj], with the released object stage [RlsObjSt], at the
output. All other aggregates are fixed at the released stage value. If none of the aggregates is marked
Release, the aggregate of the current sequence step is released to the control system.