As a new Domoticz user and member of this forum, it's my pleasure to share the script i've developed to heat my chalet in the french Alps.
This script provides heating control in a room, providing different modes (Comfort, Eco), according to presence in the room and to a couple of setpoints. The heating control is proposed through two differents algorithms (Hysterisis or PID). The script supports multiple temperature control devices used in fallback, and multiple heating devices used simultaneously.
A power consumption computation is made, based on the declared power consumption of each heating device.
Required Domoticz configuration :
- A Thermostat to set the comfort temperature, created with Dummy hardware and a Thermostat device
Variable : sSetPointConfortDeviceName
- A Thermostat to set the eco temperature, created with Dummy hardware and a Thermostat device
Variable : sSetPointEcoDeviceName
- A Mode switch to set and program with timers the heating scenarii, created with Dummy hardware and a Selector Switch device
Variable : sHeatingModeDeviceName
- A Control Mode switch to switch between the Hysterisis and PID ways of control.
Variables : sHeatingControlModeDeviceName
sHeatingControlModePIDName, sHeatingControlModeHysteresisName are used for the name given to either mode.
- A Presence detection switch. The switch would be controlled either by hand or by some external scripts/commands.
Variable : sPresenceDeviceName
- An Electricity consumption meter, created with an Instant+Counter meter
Variable : sPowerMeterDeviceName
Script configuration
- A few variables need to be set in the script, to fit with your Domoticz instance.
- Heaters
One or more heaters have to be declared in an array, together with their power consumption and commands.
Variable : aHeatingDeviceNames
- Temperature sensors
They are declared in a array, with fall back mode implemented. The script is written for sensors that gather both temperature and humidity.
Variable : aTempSensorDeviceNames
- User variables
- fISumLast, a float value initialized to 0, that's the PID current integral value ;
- fTempLastInput, a float value initialized to 0, used for the PID derivative computation ;
- fSetpointLast, a float value initialized to 0, used to check a setpoint change ;
- iResetDeviceMeterTime, an integer value initialized to 0, used to record the power meter reset time.
The PID parameters are to be determined for your own installation. Three parameters need to be calculated,
according to the following formulas :
Kp = ΔPV / ΔCO -- On steady temperature states, ratio of temperature difference for command difference
Tp -- Time needed to reach 63% of the setpoint
θp -- Time between action on the heating and measurable reaction of the temperature sensor
Tc -- Response time, highest value among 0.1Tp or 0.8θp (agressive), 1Tp or 8θp (middle), 10Tp or 80θp (conservative)
Kc = P = (1/Kp)*(Tp/(θp+Tc)) -- Our fPIDKp
I = Kc/Ti -- Our fPIDKi
Td = (Tp x θp)/(2Tp+θp) -- Needed to compute the last constant
D = Kc * Td -- Our fPIDKd
The resulting temperature control is very good for my usage. Here is a temperature graph for going to a setpoint of 15 Celsius :
- pid-regul-temp-1s1.png (100.14 KiB) Viewed 5253 times
http://brettbeauregard.com/blog/category/pid/
http://www.rhaaa.fr/regulation-pid-comment-la-regler-12
http://controlguru.com
I also thank a lot the members of this forum, and the ones of the french easydomoticz.com forum.
If this script is useful to you, i would be very happy to read about it, especially if it brought more comfort
and energy saving.
Thank you
Greg
Code: Select all
--[[
Type : Time
Name : script_time_heating.lua
Description : Controls heating in a room with hysterisis or PID method
Usage : Place in scripts/lua directory of Domoticz instance
This script provides heating control in a room, providing different modes (Comfort, Eco), according
to presence in the room and to a couple of setpoints. The heating control is proposed through
two differents algorithms (Hysterisis or PID). The script supports multiple temperature control
devices used in fallback, and multiple heating devices used simultaneously.
A power consumption computation is made, based on the declared power consumption of each heating device.
Required Domoticz configuration :
- A Thermostat to set the comfort temperature, created with Dummy hardware and a Thermostat device
Variable : sSetPointConfortDeviceName
- A Thermostat to set the eco temperature, created with Dummy hardware and a Thermostat device
Variable : sSetPointEcoDeviceName
- A Mode switch to set and program with timers the heating scenarii, created with Dummy hardware and a Selector Switch device
Variable : sHeatingModeDeviceName
- A Control Mode switch to switch between the Hysterisis and PID ways of control.
Variables : sHeatingControlModeDeviceName
sHeatingControlModePIDName, sHeatingControlModeHysteresisName are used for the name given to either mode.
- A Presence detection switch. The switch would be controlled either by hand or by some external scripts/commands.
Variable : sPresenceDeviceName
- An Electricity consumption meter, created with an Instant+Counter meter
Variable : sPowerMeterDeviceName
- Heaters
One or more heaters have to be declared in an array, together with their power consumption and commands.
Variable : aHeatingDeviceNames
- Temperature sensors
They are declared in a array, with fall back mode implemented. The script is written for sensors that gather both temperature and humidity.
Variable : aTempSensorDeviceNames
- User variables
- fISumLast, a float value initialized to 0, that's the PID current integral value ;
- fTempLastInput, a float value initialized to 0, used for the PID derivative computation ;
- fSetpointLast, a float value initialized to 0, used to check a setpoint change ;
- iResetDeviceMeterTime, an integer value initialized to 0, used to record the power meter reset time.
The PID parameters are to be determined for your own installation. Three parameters need to be calculated,
according to the following formulas :
Kp = ΔPV / ΔCO -- On steady temperature states, ratio of temperature difference for command difference
Tp -- Time needed to reach 63% of the setpoint
θp -- Time between action on the heating and measurable reaction of the temperature sensor
Tc -- Response time, highest value among 0.1Tp or 0.8θp (agressive), 1Tp or 8θp (middle), 10Tp or 80θp (conservative)
Kc = P = (1/Kp)*(Tp/(θp+Tc)) -- Our fPIDKp
I = Kc/Ti -- Our fPIDKi
Td = (Tp x θp)/(2Tp+θp) -- Needed to compute the last constant
D = Kc * Td -- Our fPIDKd
This script distributed under the GPL license. Please see https://www.gnu.org/licenses/gpl.html
--]]
-- Zone name
local sZoneName = 'Living room'
-- Setpoint
local sSetPointConfortDeviceName = 'Thermostat Confort' -- Thermostat for comfort Setpoint
local sSetPointEcoDeviceName = 'Thermostat Eco' -- Thermostat for eco Setpoint
-- Power Meter
local sPowerMeterDeviceName = 'Consommation Chauffage' -- Power meter based on configured heating devices consumption
-- Modes
-- These modes belong to the heating mode selector switch
local sHeatingModeDeviceName = 'Mode Chauffage'
local sHeatingModeComfortName = 'Confort'
local sHeatingModeEcoName = 'Eco'
local sHeatingModeForceOnName = 'Force'
local sHeatingModeFrostFreeName = 'Off'
-- Heating control mode (PID or Hysteresis)
local sHeatingControlModeDeviceName = 'Mode Controle Chauffage'
local sHeatingControlModePIDName = 'PID' -- Selection switch name for PID
local sHeatingControlModeHysteresisName = 'Hysteresis' -- Selection switch name for hysterisis mode
local fHysteresis = 0.4 -- Hysterisis value
-- Sensors
-- Will be choosen in fallback. Second parameter is a delta to the first temp sensor
local aTempSensorDevices = {
{ 'Living-room 1',0 } ,
{ 'Chambre Enfant',1.2 } -- The room is usually ~1.2 deg hotter than the living room
}
local sPresenceDeviceName = 'Presence' -- Presence device switch. Heating goes in Eco mode when Presence is Off.
-- Heaters
-- Domoticz Device Name, power in Watts, On command, Off command.
local aHeatingDevices = {
{ 'Hors-Gel Radiateur Salon Est', 1500 , 'Off AFTER 3', 'On' } ,
{ 'Hors-Gel Radiateur Salon Sud', 1500 , 'Off AFTER 3', 'On' }
}
-- PID - Proportional, Integral, Derivative - Parameters
local iHeatingCycleDuration = 10 -- Duration of a heating cycle in minutes, to be adapted to the heating devices
local fPIDKp = 113 -- Change this !
local fPIDKi = 0.05 -- Change this !
local fPIDKd = 30045 -- Change this !
-- Alerts
local sEmailContact = '[email protected]'
-- Debug
local bDebug = true
---------------------------------------------- End of configuration section ----------------------------------------------
-- Variables
local fCurrentTemp = 1000
-- Statics variables
-- Heating commands, constants not to be changed
local sHeatingOnCommand = 'ON'
local sHeatingOnForCommand = 'ONFOR'
local sHeatingOffCommand = 'OFF'
-- Functions
function prDebug(sString)
if(bDebug) then
print ( sString )
end
end
function addCommand( sDevice, sCommand )
commandArray[#commandArray+1] = { [sDevice] = sCommand }
end
function timeDifference(sDeviceName)
sDeviceTimeChanged = otherdevices_lastupdate[sDeviceName]
sYear = string.sub(sDeviceTimeChanged, 1, 4)
sMonth = string.sub(sDeviceTimeChanged, 6, 7)
sDay = string.sub(sDeviceTimeChanged, 9, 10)
sHour = string.sub(sDeviceTimeChanged, 12, 13)
sMinutes = string.sub(sDeviceTimeChanged, 15, 16)
sSeconds = string.sub(sDeviceTimeChanged, 18, 19)
t1 = os.time()
t2 = os.time{year=sYear, month=sMonth, day=sDay, hour=sHour, min=sMinutes, sec=sSeconds}
return os.difftime (t1, t2)
end
function round(fNumber, iPrecision)
local iMult = 10^(iPrecision or 0)
return math.floor(fNumber * iMult + 0.5) / iMult
end
function commandHeating(sCommand,iTime)
local fIntervalEnergy = 0
local fInstantPower = 0
-- Send command to heaters, calculate power and energy
for iHeatingDeviceIndex = 1, #aHeatingDevices do
local sActiveHeatingDevice = aHeatingDevices[iHeatingDeviceIndex]
fInstantPower = fInstantPower + sActiveHeatingDevice[2]
if( sCommand == sHeatingOnForCommand ) then
fIntervalEnergy = fIntervalEnergy + (tonumber(fInstantPower) / 60 ) * iHeatingCycleDuration
else
fIntervalEnergy = fIntervalEnergy + tonumber(fInstantPower) / 60
end
if( sCommand == sHeatingOnCommand ) then
prDebug('Heating device : - '..sActiveHeatingDevice[1]..' - , power : ' .. sActiveHeatingDevice[2]..' Watts gets command : '..sActiveHeatingDevice[3])
addCommand(sActiveHeatingDevice[1],sActiveHeatingDevice[3])
end
if( sCommand == sHeatingOnForCommand ) then
prDebug('Heating device : - '..sActiveHeatingDevice[1]..' - , power : ' .. sActiveHeatingDevice[2]..' Watts gets command : '..sActiveHeatingDevice[3]..' FOR '..tostring(iTime))
addCommand(sActiveHeatingDevice[1],sActiveHeatingDevice[3] .. ' FOR ' .. tostring(iTime)) -- Can be missed :-( --> zwave!
end
if( sCommand == sHeatingOffCommand ) then
prDebug('Heating device : - '..sActiveHeatingDevice[1]..' - , power : ' .. sActiveHeatingDevice[2]..' Watts gets command : '..sActiveHeatingDevice[4])
addCommand(sActiveHeatingDevice[1],sActiveHeatingDevice[4])
end
end
-- Energy accounting
-- Get current power-meter values
sCurrentPower,sCurrentTotalEnergy = string.match(otherdevices_svalues[sPowerMeterDeviceName], "(%d+%.*%d*);(%d+%.*%d*)" )
local fCurrentTotalEnergy = tonumber(sCurrentTotalEnergy)
if(sCommand == sHeatingOffCommand ) then -- No instant power consumption
addCommand('UpdateDevice', iPowerMeterIdx .. '|0|0;' .. sCurrentTotalEnergy)
return
end
fUpdatedEnergy = fCurrentTotalEnergy + fIntervalEnergy
if(sCommand == sHeatingOnForCommand ) then -- System heating iTimes minutes
addCommand('UpdateDevice', iPowerMeterIdx .. '|0|' .. fInstantPower .. ';' .. fUpdatedEnergy)
addCommand('Variable:iResetDeviceMeterTime',tostring(iTime))
end
if(sCommand == sHeatingOnCommand ) then -- System in On/Off mode, heating happends until a stop command
-- Total instant power update
addCommand('UpdateDevice', iPowerMeterIdx .. '|0|' .. fInstantPower .. ';' .. fUpdatedEnergy)
end
end
-- Init
commandArray = {}
iPowerMeterIdx = otherdevices_idx[sPowerMeterDeviceName]
-- Get time
local sCurrentTime = string.sub(os.date("%X"), 1, 5)
local sCurrentMinute = os.date('%M')
-- Check temperature sensors, choose the first one with response time < 10 min
-- set setpoint delta
for iTempSensorIndex = 1, #aTempSensorDevices do
prDebug('Temp Sensor Device : '..aTempSensorDevices[iTempSensorIndex][1]..' - Delta to reference : ' .. aTempSensorDevices[iTempSensorIndex][2] )
sTempSensorDeviceName = aTempSensorDevices[iTempSensorIndex][1]
sTempSensorDeltaToReference = aTempSensorDevices[iTempSensorIndex][2]
-- Last seen ?
local sTempSensorLastSeen = string.sub(os.date("!%X", timeDifference(sTempSensorDeviceName)), 1, 5)
-- if (sTempSensorLastSeen >= '00:10' and sTempSensorLastSeen < '00:12') then
if (sTempSensorLastSeen >= '00:10') then
prDebug('Temp sensor missing')
addCommand('SendEmail',sZoneName..' Heating Alert#Temperature sensor '..sTempSensorDeviceName..' has not updated for more than 10m.#'..sEmailContact)
else -- Sensor has been seen, we use it
sCurrentTemp,sCurrentHumidity = string.match(otherdevices_svalues[sTempSensorDeviceName],"(%d+%.*%d*);(%d+%.*%d*)")
fCurrentTemp = tonumber(sCurrentTemp) + tonumber(sTempSensorDeltaToReference)
prDebug ('Current measured temperature and delta applied : '..fCurrentTemp)
break
end
end
if ( fCurrentTemp == 1000) then return commandArray end -- No temp sensor, end of execution
-- Check for energy accounting timer to reset the meter
local iResetMeterDeviceTime = tonumber(uservariables['iResetDeviceMeterTime'])
if ( iResetMeterDeviceTime > 0 ) then -- There is an ongoing power consumption
local iNewResetDeviceMeterTime = iResetMeterDeviceTime - 1
if( iNewResetDeviceMeterTime == 0) then
-- reset energy counters on time
sCurrentPower,sCurrentTotalEnergy = string.match(otherdevices_svalues[sPowerMeterDeviceName], "(%d+%.*%d*);(%d+%.*%d*)" )
addCommand('UpdateDevice', iPowerMeterIdx .. '|0|0;' .. sCurrentTotalEnergy)
end
addCommand('Variable:iResetDeviceMeterTime',tostring(iNewResetDeviceMeterTime))
end
-- Get current heating mode
sHeatingMode = otherdevices[sHeatingModeDeviceName]
-- Heating in Eco or Comfort, needs a calculation
if ( sHeatingMode == sHeatingModeComfortName
or
sHeatingMode == sHeatingModeEcoName
)
then
-- Inits
bPresence = false
fSetPointTemp = 7
-- Check for presence
sPresenceDeviceStatus = otherdevices[sPresenceDeviceName]
if ( sPresenceDeviceStatus == 'On' ) then
prDebug('Presence is on')
bPresence = true
else
prDebug('Presence is off')
bPresence = false
end
-- Comfort mode, set heating setpoint to thermostat value, only applies if Presence is true.
if( (sHeatingMode == sHeatingModeComfortName) and bPresence ) then
fSetPointTemp = tonumber(otherdevices_svalues[sSetPointConfortDeviceName])
prDebug ('Heating in *Comfort mode*, Setpoint : '..fSetPointTemp..' at '..sCurrentTime)
end
-- Eco mode, setpoint adjusted. Use this setpoint if no Presence.
if( sHeatingMode == sHeatingModeEcoName or bPresence == false) then
fSetPointTemp = tonumber(otherdevices_svalues[sSetPointEcoDeviceName])
prDebug ('Heating in *Eco mode*, Setpoint : '..fSetPointTemp..' at '..sCurrentTime)
end
-- Control mode
local sControlMode = otherdevices[sHeatingControlModeDeviceName]
prDebug('Heating Control mode : ' .. sControlMode)
if( sControlMode == sHeatingControlModeHysteresisName ) then -- Control mode set to hysteresis
-- Decision to heat or not
-- Is it cold ?
if(fCurrentTemp <= (fSetPointTemp - fHysteresis) ) then
prDebug ('Heating needed with delta : ' .. fCurrentTemp - fSetPointTemp)
-- startHeating(aHeatingDeviceNames) --GH get rid of variable
commandHeating(sHeatingOnCommand)
end
-- Is it warm ?
if(fCurrentTemp >= (fSetPointTemp + fHysteresis) ) then
prDebug ('Stopping heating needed with delta : ' .. fCurrentTemp - fSetPointTemp)
-- stoptHeating(aHeatingDeviceNames)
commandHeating(sHeatingOffCommand)
end
end
if( sControlMode == sHeatingControlModePIDName ) then -- Control mode set to PID
-- We control the execution frequency
if( sCurrentMinute % iHeatingCycleDuration == 0) then -- We run the cycle
-- Set PID coefficients according to sample time
local fPIDTKi = fPIDKi * iHeatingCycleDuration * 60
local fPIDTKd = fPIDKd / (iHeatingCycleDuration * 60)
-- Current temperature error
fTempError = fSetPointTemp - fCurrentTemp
-- Compute new Integral
-- If Setpoint changed, reset the integral action
if( fSetPointTemp ~= tonumber(uservariables['fSetpointLast']) ) then
fISum=0
else
-- Get the last Integral
fISum = uservariables['fISumLast']
end
fISum = fISum + (fPIDTKi * fTempError)
-- if(fISum > 255) then fISum = 255 end
if(fISum > 255) then fISum = 255 end -- Integral limitation
if(fISum < 0) then fISum = 0 end
-- Derivative computation
local fDeltaInput = fCurrentTemp - uservariables['fTempLastInput'] -- to number
-- Sum up the PID output
local fPIDOutput = fPIDKp * fTempError + fISum - fPIDTKd * fDeltaInput
prDebug('PID Output : fPIDKp * fTempError = ' ..fPIDKp..' * '..fTempError..' = '..fPIDKp*fTempError..', fISum + '..fPIDTKi * fTempError..' = '..fISum..', -fPIDTKd * fDeltaInput = '..fPIDTKd..' * '..fDeltaInput..' = -' .. fPIDTKd*fDeltaInput..', Output : '..fPIDOutput)
if(fPIDOutput > 255) then fPIDOutput = 255 end
if(fPIDOutput < 0) then fPIDOutput = 0 end
-- Update user variables for next cycle
addCommand('Variable:fTempLastInput',tostring(fCurrentTemp))
addCommand('Variable:fISumLast',tostring(fISum))
addCommand('Variable:fSetpointLast',tostring(fSetPointTemp))
-- Heating cycle duration calculation
if( fPIDOutput > 0 ) then -- heat
fCycleDuration = round(fPIDOutput * iHeatingCycleDuration / 255,0)
if( fCycleDuration == 0 ) then fCycleDuration = 1 end -- Heating is needed, let's go for at least 1 minute
prDebug('Going to heat for : ' ..fCycleDuration..' minutes during the next '..round(iHeatingCycleDuration*60)..' seconds ('..iHeatingCycleDuration..' minutes) period.' )
commandHeating(sHeatingOnForCommand,fCycleDuration)
else -- Output null or negative, stop the heating
prDebug('No heating needed')
commandHeating(sHeatingOffCommand)
end
end -- Time period
end -- PID mode
end
-- Heating forced on
if ( sHeatingMode == sHeatingModeForceOnName )
then
prDebug('Heaters forced On')
commandHeating(sHeatingOnCommand)
end
-- Heating forced off
if ( sHeatingMode == sHeatingModeFrostFreeName )
then
prDebug('Heaters forced Off - Anti-frost mode')
commandHeating(sHeatingOffCommand)
end
return commandArray
