The ‘Combined Heat and Power’ template consists of CHP combined with a storage tank and a basic control strategy, written out in the controller.
CHP - Basic control
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Working principle
The programmable controller controls the CHP. It gives the setpoint to the external PI-controller for controlling the 3-way valve to achieve a certain return temperature. Internally it will enable or disable the CHP and it will calculate the modulation based on the measured return temperature (see figure below).
The CHP is enabled on 4 conditions:
Measured The measured return temperature is lower than the maximum return temperature.
Once the CHP has been disabled the sequence to enable the CHP shall be inhibited for 10 minutes -> check of if this timer has run out.
Number A number of starts within 24h is lower than 6.
Temperature The temperature in TES is lower than 70°C.
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The CHP is released based on 4 conditions:
Measured The measured return temperature is lower than the maximum return temperature.
Once the CHP has been disabled the sequence to enable the CHP shall be inhibited for 10 minutes.
Number of starts in 24h is lower than 6.
Temperature The temperature in the thermal store is lower than 70°C.
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The user can change the design temperatures, thermal power, and end units… But keep in mind that the controls have to be changed as well. This can be done by changing the “settings” in the programmable controller which are listed in at the top of the code. After changes in the settings, the correct operation has to be checked again. The user should only change the “settings” and nothing else in the code to make sure the correct control strategy is still valid.
If the user changes the power of the end - units, the thermal capacity of the CHP doesn’t change automatically. The user should implement a correct capacity corresponded corresponding with the thermal power of the CHP.
More information about the CHP can be found in CHP (Combined Heat & Power).
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