The district heating heat exchanger controls the secondary supply temperature. The secondary supply temperature setpoint is equal to the heat demand of the connected consumers at the input "Heat_Demand". This setpoint is increased by the value of the parameter SST-04, e.g. 5 K.
The setpoint is ramped up as defined by the setpoint ramp SST-05. The setpoint is limited between the minimum and maximum supply temperature limits, defined by the parameters SST-02 and SST-01 as shown in the next figure.
Fig. 2. SST Setpoint Ramp
Depending on the calculated P-band, the integral action time, the D-time and the calculated system supply temperature setpoint, the valve control signal varies from 0...100% as shown in the next figure.
Fig. 3. SST Control
Table 1. Parameter List
Description |
Value Range |
Default Value |
Unit |
SST-01: maximum supply temperature |
50...200 |
90 |
°C |
SST-02: minimum supply temperature |
0...90 |
10 |
°C |
SST-04: setpoint increase to compensate losses |
0...20 |
5 |
K |
SST-05: maximum setpoint increase per minute |
1...100 |
25 |
K |
SST-06: P-band SST control |
1...1000 |
20 |
K |
SST-07: I-time system supply temperature control |
0...3600 |
300 |
sec |
SST-08: D-time system supply temperature control |
0...1000 |
0 |
sec |