DH - Control

This control VI does not contain any logic that provides operation set points for the heat grid outlet temperature. The tasks of this control VI are:

• Controling control valves that ensure the inlet and outlet flow rate are the same
• Controling the mixing valves to cool down the outlet temperature
• Controling the electric heater to heat up the outlet temperature

The emulator has 6 modes:

0. Cooling
1. Heating
2. Heating to Cooling (to be reviewed)
3. Cooling to Heating (to be reviewed)
4. Module as Heat Source
5. Direct Control

ToDo: In cooling mode the in- and outflowing volume flows should match. In order to do this, the CV_OUT valve is controlled. This functionality has to be reworked in order to make it independent of the flow direction (and the measured signs) of the flows trough the DH module.

Grid emulator to emulate the district heating grid (Mode 0 - 3)

The easiest way is to provide inputs with the HiL model. Inputs that can be provided by the HiL model are marked blue. This model provides the necessary input values according to simulation data.

Two thesises provided the general structure of the control:

• General control structure (master thesis of Christian Huber)
• Improvement, where the electric heaters with their high thermal inertia can be bypassed (bachelor thesis of Luis Theel)

Inputs:

• Set outlet temperature : S_TM-TG_OU_set $//<![CDATA[ \begin{array}{l}[°C]\end{array} //]]>$
• Inlet temperature in the future: T_in_future $//<![CDATA[ \begin{array}{l}[°C]\end{array} //]]>$
  Best to be defined by the heat transfer station
• Control modeBest to be defined by the heat transfer station

Outputs:

• Temperatures and flow rates as shown in DH - Hardware $//<![CDATA[ \begin{array}{l}[l/min]\end{array} //]]>$ and $//<![CDATA[ \begin{array}{l}[°C]\end{array} //]]>$

Grid emulator as heat source (Mode 4)

The grid emulator can also function as a heat source, e.g. if the flow and temperature through the district heating station should be provided.

Inputs:

• Set outlet temperature: T_set $//<![CDATA[ \begin{array}{l}[°C]\end{array} //]]>$
• Set outlet flowrate: V_set $//<![CDATA[ \begin{array}{l}[l/min]\end{array} //]]>$

Direct Control (Mode 5)

The actuators can be controlled directly by 0-10 or digital output signals.

Inputs:

• A_CV-CC_IN: 0-10V

• A_CV-CC_OU: 0-10V

• A_MX-4W-TG: 0-10V

• A_MX-3W-TG: 0-10V

• A_EH-TG: 0-10V