modelHeaterControl

Information

HeaterControl models a heater control system for maintaining a specific temperature at the heater's outlet. It adjusts the mass flow rate of the pump connected to the heater based on tank levels and temperature setpoints. The model includes a PI controller to regulate the heater's mass flow rate to achieve the desired outlet temperature. The model can turn on/off the PI by using a switch that sets the mass flow rate to a user-specified minimum.

The model features the following connectors:

A RealInput connector for the measured ambient temperature (in K).
A RealInput connector for the fluid temperature at the heater outlet (in K).
A RealOutput connector for the mass flow rate pumped to the heater (in kg/s).
A BooleanInput connector for the on/off signal from the heater power supply.
A RealInput connector for the scheduled discharge mass flow rate (in kg/s).
A RealInput connector for the mass flow rate of the pump charging the tank (in kg/s).
A RealInput connector for the instantaneous tank level (in meters).

The model includes the following parameters:

T_heater_set: Setpoint of temperature (in K). Default: 565 Celsius.
m_flow_max: Maximum discharge mass flow rate (in kg/s). Default: 1400 kg/s.
m_flow_min: Mass flow rate when control is off (in kg/s). Default: 0 kg/s.
level_on: Level of start discharge (in meters). Default: 30 %.
level_off: Level of stop discharge (in meters). Default: 10 %.
level_curtailment_on: Level of start curtailment (in meters). Default: 99 %.
level_curtailment_off: Level of stop curtailment (in meters). Default: 96 %.
y_start: Initial value of output for the PI controller (in kg/s). Default: 300 kg/s.
Ti: Integer constant for the PI controller. Default: 1 s.
Kp: Proportional constant for the PI controller. Default: -10 Hz.

The model is equipped with a PI controller, logic blocks for discharge and curtailment control, and feedback mechanisms to adjust the heater's operation.

Parameters

Type	Name	Default	Description
SI.Temperature	T_heater_set	from_degC(565)	Heater setpoint of temperature
SI.MassFlowRate	m_flow_max	1400	Maximum discharge mass flow rate
SI.MassFlowRate	m_flow_min	0	Mass flow rate when control off
Real	level_on	30	Level of start discharge
Real	level_off	10	Level of stop discharge
Real	level_curtailment_on	99	Level of start curtailment
Real	level_curtailment_off	96	Level of stop curtailment
Real	y_start	300	Initial value of output
Real	Ti	1	Integer constant
Real	Kp	-10	Proportional constant

Connectors

Type	Name	Description
Modelica.Blocks.Interfaces.RealInput	tank_level	Level of the tank connected to the heater
Modelica.Blocks.Interfaces.RealOutput	m_flow_heater	Mass flow rate pumped to the heater
Modelica.Blocks.Interfaces.BooleanInput	on_input_signal	On/off signal from heater power supply
Modelica.Blocks.Interfaces.RealInput	T_heater_measured	Fluid temperature at the heater outlet
Modelica.Blocks.Interfaces.BooleanOutput	curtailment

Components

Type	Name	Description
Modelica.Blocks.Logical.Switch	switch	PI controller on/off switch
Modelica.Blocks.Sources.RealExpression	m_flow_heater_off	Mass flow rate when heater is off
Modelica.Blocks.Math.Feedback	feedback
SolarTherm.Models.Control.PID_AW_reset3	PI	PI Controller to adjust heater mass flow rate to meet the temperature set point
Modelica.Blocks.Sources.RealExpression	T_heater_set_connector	Real connector to feedback
SolarTherm.Models.Control.Level2Logic	tank_discharge_logic	Algorithm to start/stop discharge of tank based on tank level
Modelica.Blocks.Logical.And	and1
SolarTherm.Models.Control.Level2Logic	curtailment_logic	Algorithm to curtail the heater power supply
Modelica.Blocks.Logical.Not	not1

Revisions

September 2023 by Armando Fontalvo:
Created documentation for HeaterControl.