HeatpumpGasboilerSelection

HeatpumpGasboilerSelection (FB)

FUNCTION_BLOCK HeatpumpGasboilerSelection

Short description

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

1. Current COP value of the heat pump

2. Cost for 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 curve match the COP curve W35-heating case of the WP Remeha E-HP AW 84. Typical application: Decision about releasing 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 (or curves) (FALSE = invalid)

Outputs

Name	Data type	Value range	Initial value	Function
tRemainingTimeTestIntervall	TIME		T#0s	Remaining time until the next test point
rCOPLimit	REAL		0.0	Threshold of the COP for enabling the heat pump (rCOP >= rCOPLimit: heat pump enabled)
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 generation with the gas boiler
rEfficiencyHeatpump	REAL		0.9	Overall efficiency of heat generation with the heat pump
rEnergyPriceGasboiler	REAL		0.20	Energy costs - gas (in euros / kWh of generated heat energy)
rEnergyPriceHeatpump	REAL		0.45	Energy costs - 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 release of the heat generators gas boiler or heat pump is made based on a calculation taking into account the following influencing factors: 1) Current COP value of the heat pump 2) Cost for 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 on a rising edge at the input *xEn* 3) Once after each restart 4) Once on every change of the COP source selection *eCOPSource* The COP value of the heat pump can be determined either by an internally stored curve with 10 value pairs (*eCOPSource* = Internal_Curve, temperature of the heat source *rSourceTempCOP*) or by the external input *rExtCOP* (*eCOPSource* = External_Input, *xExtError* = FALSE, *xExtValidData* = TRUE). It is limited by the absolute bounds **rCOP_Min** and **rCOP_Max**, output at the *rCOP* output if error-free, 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 sequentially either strictly increasing or strictly decreasing 2) Each X value may only occur once 3) Two adjacent support points are connected by a straight line each time At the *tRemainingTimeTestIntervall* output the remaining time until the next cyclic calculation is available. At the *rCOPLimit* output the threshold for switching to the gas boiler is available (rCOP < rCOPLimit: gas boiler enabled) In the disabled state (*xEn* = FALSE) the outputs assume meaningful, constant values; no calculation takes place anymore. At the *xError* output 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)