HeatpumpGasboilerSelection

HeatpumpGasboilerSelection (FB)

FUNCTION_BLOCK HeatpumpGasboilerSelection

Short description

Enablement of the gas boiler or the heat pump depending on various influencing factors. Influencing factors:

1. Current COP value of the heat pump

2. Cost of electrical energy (heat pump) in euros per kWh

3. Cost for natural gas supply (gas boiler) in euros per kWh

4. Efficiency of the heat pump (0.0 - 1.0)

5. Efficiency of the gas boiler (0.0 - 1.0)

The default settings of the internal characteristic curve match the COP curve W35-heating case of the WP Remeha E-HP AW 84. Typical application: Decision on enabling the gas boiler or the heat pump depending on the operating situation

Representation

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
xEn	BOOL		TRUE	Enable / disable the function block (TRUE = enabled)
eCOPSource	eHeatpumpGasboilerSelection_COPSource		eHeatpumpGasboilerSelection_COPSource.Internal_Curve	Selection of the COP source (Internal_Curve, External_Input)
rSourceTempCOP	REAL		2.0	Current temperature of the heat source for the heat pump (air-water HP: outside temperature)
rExtCOP	REAL		4.0	External value of the coefficient of performance (COP) of the heat pump (typical: 2.0 - 7.0)
xExtError	BOOL		FALSE	External error state (FALSE = no error, TRUE = error)
xExtValidData	BOOL		FALSE	External input for the validity of the curve data (n) (FALSE = invalid)

Outputs

Name	Data type	Value range	Initial value	Function
tRemainingTimeTestIntervall	TIME		T#0s	Remaining time until the next test time point
rCOPLimit	REAL		0.0	Threshold of the COP for enabling the heat pump (rCOP >= rCOPLimit: enable the heat pump)
rCOP	REAL		0.0	Current value of the coefficient of performance (COP) of the heat pump (typical: 2.0 - 7.0)
xCmdGasboiler	BOOL		FALSE	Enable / disable the gas boiler (TRUE = enabled)
xCmdHeatpump	BOOL		FALSE	Enable / disable the heat pump (TRUE = enabled)
xError	BOOL		FALSE	Error state (FALSE = no error, TRUE = error)

Setpoints / parameters

Name	Data type	Value range	Initial value	Function
rEfficiencyGasboiler	REAL		0.9	Overall efficiency of heat production with the gas boiler
rEfficiencyHeatpump	REAL		0.9	Overall efficiency of heat production with the heat pump
rEnergyPriceGasboiler	REAL		0.20	Energy cost - gas (in euros / kWh of produced heat energy)
rEnergyPriceHeatpump	REAL		0.45	Energy cost - electricity (in euros / kWh)
tTimeTestIntervall	TIME		T#30M	Duration of the test interval
rCOP_Subst	REAL		3.5	Substitute value for the COP in case of error
rCOP_Min	REAL		1.0	Absolute minimum value of the COP
rCOP_Max	REAL		10.0	Absolute maximum value of the COP
rSP1_X	REAL		1.0	Support point 1 - X value
rSP1_Y	REAL		2.0	Support point 1 - Y value
rSP2_X	REAL		2.0	Support point 2 - X value
rSP2_Y	REAL		4.0	Support point 2 - Y value
rSP3_X	REAL		3.0	Support point 3 - X value
rSP3_Y	REAL		6.0	Support point 3 - Y value
rSP4_X	REAL		4.0	Support point 4 - X value
rSP4_Y	REAL		8.0	Support point 4 - Y value
rSP5_X	REAL		5.0	Support point 5 - X value
rSP5_Y	REAL		10.0	Support point 5 - Y value
rSP6_X	REAL		6.0	Support point 6 - X value
rSP6_Y	REAL		12.0	Support point 6 - Y value
rSP7_X	REAL		7.0	Support point 7 - X value
rSP7_Y	REAL		14.0	Support point 7 - Y value
rSP8_X	REAL		8.0	Support point 8 - X value
rSP8_Y	REAL		16.0	Support point 8 - Y value
rSP9_X	REAL		9.0	Support point 9 - X value
rSP9_Y	REAL		18.0	Support point 9 - Y value
rSP10_X	REAL		10.0	Support point 10 - X value
rSP10_Y	REAL		20.0	Support point 10 - Y value

Function description

The enablement of the heat generators gas boiler or heat pump is determined by a calculation taking into account the following influencing factors: 1) Current COP value of the heat pump 2) Cost of electrical energy (heat pump) in euros per kWh 3) Cost for natural gas supply (gas boiler) in euros per kWh 4) Efficiency of the heat pump (0.0 - 1.0) 5) Efficiency of the gas boiler (0.0 - 1.0) Only one heat generator is enabled at any time; the other is automatically disabled. This calculation is performed (condition: xEn = TRUE) if at least one of the following situations occurs: 1) Cyclically at interval tTimeTestIntervall 2) Once at a rising edge on the input xEn 3) Once after every restart 4) Once at every change of the COP source selection eCOPSource The COP value of the heat pump can be determined by an internally stored curve with 10 value pairs (eCOPSource = Internal_Curve, heat source temperature rSourceTempCOP) or by the external input rExtCOP (eCOPSource = External_Input, xExtError = FALSE, xExtValidData = TRUE). It is limited by the absolute bounds rCOP_Min or rCOP_Max and, if error-free, output at the rCOP output and used for the calculation. In case of error (eCOPSource = Internal_Curve: error in the input of the value pairs) or (eCOPSource = External_Input: xExtError = TRUE or xExtValidData = FALSE) the substitute value rCOP_Subst is used. The X-values of the 10 support points of the internal COP curve must meet the following boundary conditions: 1) The X-values must be either strictly increasing or strictly decreasing 2) Each X-value may only occur once 3) Two adjacent support points are each connected by a straight line At the output tRemainingTimeTestIntervall the remaining time until the next cyclic calculation is available. At the output rCOPLimit the threshold for switching to the gas boiler is available (rCOP < rCOPLimit: enable the gas boiler) In the disabled state (xEn = FALSE) the outputs take on sensible, constant values; no calculation is performed. At the output *xError* the current error state is available (xError = TRUE: error active). It is active if either the internal COP curve is faulty or the external error input xExtError is active (= TRUE).

CODESYS

InOut:

Scope	Name	Type	Initial
Input	xEn	BOOL	TRUE
Input	eCOPSource	eHeatpumpGasboilerSelection_COPSource	eHeatpumpGasboilerSelection_COPSource.Internal_Curve
Input	rSourceTempCOP	REAL	2.0
Input	rExtCOP	REAL	4.0
Input	xExtError	BOOL	FALSE
Input	xExtValidData	BOOL	FALSE
Output	tRemainingTimeTestIntervall	TIME	TIME#0ms
Output	rCOPLimit	REAL	0.0
Output	rCOP	REAL	0.0
Output	xCmdGasboiler	BOOL	FALSE
Output	xCmdHeatpump	BOOL	FALSE
Output	xError	BOOL	FALSE
Input Const	rSP10_Y	REAL	6.8
Input Const	rSP10_X	REAL	20.0
Input Const	rSP9_Y	REAL	5.85
Input Const	rSP9_X	REAL	16.1
Input Const	rSP8_Y	REAL	5.25
Input Const	rSP8_X	REAL	12.2
Input Const	rSP7_Y	REAL	4.65
Input Const	rSP7_X	REAL	8.3
Input Const	rSP6_Y	REAL	4.2
Input Const	rSP6_X	REAL	4.4
Input Const	rSP5_Y	REAL	3.7
Input Const	rSP5_X	REAL	0.5
Input Const	rSP4_Y	REAL	3.35
Input Const	rSP4_X	REAL	-3.3
Input Const	rSP3_Y	REAL	3.1
Input Const	rSP3_X	REAL	-7.2
Input Const	rSP2_Y	REAL	2.95
Input Const	rSP2_X	REAL	-11.1
Input Const	rSP1_Y	REAL	2.8
Input Const	rSP1_X	REAL	-15.0
Input Const	rCOP_Max	REAL	10.0
Input Const	rCOP_Min	REAL	1.0
Input Const	rCOP_Subst	REAL	3.5
Input Const	tTimeTestIntervall	TIME	TIME#30m0s0ms
Input Const	rEnergyPriceHeatpump	REAL	0.45
Input Const	rEnergyPriceGasboiler	REAL	0.2
Input Const	rEfficiencyHeatpump	REAL	0.9
Input Const	rEfficiencyGasboiler	REAL	0.9

Methods:

mCalculateCurveSectionValue_Real_Real

mCalculateCurveValue_Real_Real

Structure:

• mCalculateCurveSectionValue_Real_Real (Method)

• mCalculateCurveValue_Real_Real (Method)