Electric waterheater
[Residential loads (residential)]

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Detailed Description

The residential electric waterheater uses a hybrid thermal model that is capable of tracking either a single-mass of water, or a dual-mass with a varying thermocline.

The driving dynamic parameters of the waterheater are

• demand: the current consumption of water in gallons/minute; the higher the demand, the more quickly the thermocline drops.
• voltage: the line voltage for the coil; the lower the voltage, the more slowly the thermocline rises.
• inlet water temperature: the inlet water temperature; the lower the inlet water temperature, the more heat is needed to raise it to the set point
• indoor air temperature: the higher the indoor temperature, the less heat loss through the jacket.

Classes
class	waterheater
Defines
#define	HEIGHT_PRECISION   0.01
#define	TSTAT_PRECISION   0.01
Functions
double	waterheater::actual_Q (void)
int	waterheater::create ()
EXPORT int	create_waterheater (OBJECT **obj, OBJECT *parent)
double	waterheater::dhdt (double h)
double	waterheater::get_Tambient (WHLOCATION water_heater_location)
int	waterheater::init (OBJECT *parent)
	Initialize water heater model properties - randomized defaults for all published variables.
EXPORT int	init_waterheater (OBJECT *obj)
double	waterheater::new_h_2zone (double h0, double delta_t)
double	waterheater::new_temp_1node (double T0, double delta_t)
double	waterheater::new_time_1node (double T0, double T1)
double	waterheater::new_time_2zone (double h0, double h1)
EXPORT TIMESTAMP	plc_waterheater (OBJECT *obj, TIMESTAMP t0)
WHQFLOW	waterheater::set_current_model_and_load_state (void)
	Set the water heater model and tank state based on the estimated temperature differential along the height of the water column when it is full, emplty or partial at the current height, given the current water draw.
void	waterheater::set_time_to_transition (void)
	Calculate the time to transition from the current state to new state.
TIMESTAMP	waterheater::sync (TIMESTAMP t0, TIMESTAMP t1)
	Water heater synchronization determines the time to next synchronization state and the power drawn since last synch.
EXPORT TIMESTAMP	sync_waterheater (OBJECT *obj, TIMESTAMP t0)
WHQSTATE	waterheater::tank_state (void)
	Tank state determined based on the height of the hot water column.
void	waterheater::thermostat (TIMESTAMP t0, TIMESTAMP t1)
	Water heater plc control code to set the water heater 'heat_needed' state The thermostat set point, deadband, tank state(height of hot water column) and current water temperature are used to determine 'heat_needed' state.
void	waterheater::update_T_and_or_h (double)
	waterheater::waterheater (MODULE *mod)
	Register the class and publish water heater object properties.
void	waterheater::wrong_model (WRONGMODEL msg)
	waterheater::~waterheater (void)
Variables
static waterheater *	waterheater::defaults = NULL
static CLASS *	waterheater::oclass = NULL

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Function Documentation

EXPORT TIMESTAMP plc_waterheater	(	OBJECT *	obj,
		TIMESTAMP	t0
	)

Todo:

If external plc codes return a timestamp, it will allow sync sooner but not later than water heater time to transition (ticket #147)

Definition at line 688 of file waterheater.cpp.

References s_object_list::clock, OBJECTDATA, thermostat(), and TS_NEVER.

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