Domoticz-VirtualThermostat-PID

Overview

Smart Virtual Thermostat with PID python plugin for Domoticz home automation system

Inspired by SmartVirtualThermostat https://www.domoticz.com/wiki/Plugins/Smart_Virtual_Thermostat.html

An internal temperature sensor is used to control a smart thermostatic radiator valve.  using a PID regulator.

Possible control modes:

• changing a TRV set point temperature
• changing an internal TRV temperature sensor value adjustment (not tested)
• replacing an internal TRV temperature sensor values by an additional sensor value (not implemented)

Current code was tested with Danfoss Living Connect Z-Wave (014G0013) and Xiaomi Mi ZigBee Temperature and Humidity Sensor WSDCG6Q01LM

Plugin creates a new device

Example of timers. Pause is applied once a week for 10 minutes to close a valve regularly.

Example of plugin settings

Parameters

Inside Temperature Sensors (csv list of idx)

List of all temperature sensors installed in the controlled room. An average is caluclated.

Example: 4,5

Open Window Sensors (csv list of idx)

List of all open window sensors installed in the controlled room.

Example: 6

Thermostat Radiator Valves (csv list of idx)

List of all TRV installed in the controlled room.

Example: 9,11

High/Low/Pause/Precision/Max shift Temperatures (csv list of values)

• High - temperature (in C) during a day
• Low - temperature (in C) during a night
• Pause - temperature (in C) used when windows are open or during Pause mode (antifreeze)
• TRV Prec - precision of valve set point (in C) - this parameter prevent too frequent changes and adds kind of histeresis
• Sensor Prec - precision of sensor (in C) - this parameter adds histeresis when sensor temperature is near the target
• Max shift - highest accepted difference between set point and target temperatur (High/Low)

Example: 21.0,20.0,5.0,0.5,0.1,3.0

Calc. interval, Pause On delay, Pause Off delay, Sensor Timeout (all in minutes):

• Calc. interval - time between calculation of PID shift
• Pause On delay - time between opening a window and virtual thermostat switching to Pause mode
• Pause Off delay - time between closing a window and virtual thermostat switching  to previous mode (Normal/Economic)
• Sensor Timeout - when temperature sensors are not responding - virtual thermostat will use only an internal TRV temperature sensor (not implemented)

Example: 3,1,10,90

PID Params P/I/D/Debug/E/C:

• Kp - proportional factor
• Ki - integral factor
• Kd - differential factor
• Debug - 1/0 debug logging on/off
• E - shift calculation mode: 1 - PID, 2 - simple delta
• C - TRV Control mode - 1 - set point, 2 - internal TRV sensor temperature value adjustment, 3 - internal TRV sensor temperature value replacement

Example: 0.9,0.1,0.2,0,1,1

Thermostat modes

• Off - virtual thermostat is not controlling TRV devices
• Normal - control TRV to achive defined higher temperture
• Economy - control TRV to achive defined lower temperture
• Pause - sets on all TRVs antifreeze temperture
• 3x Off - reload internal values from user variable - after first "Off" update user variable (i.e. "Integral")
• 3x Pause - restore default internal values

TODO:

• open window pause
• TRV control modes 2 and 3
• Sensor Timeout
• Multiple temperature sensors - min/max/avg mode - currently only avg