Secondary Supply Temperature Control

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