residential/refrigerator.cpp

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#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <math.h>

#include "house.h"
#include "refrigerator.h"

// underground_line_conductor CLASS FUNCTIONS
CLASS* refrigerator::oclass = NULL;
refrigerator *refrigerator::defaults = NULL;



refrigerator::refrigerator(MODULE *module) 
{
    // first time init
    if (oclass == NULL)
    {
        oclass = gl_register_class(module,"refrigerator",PC_BOTTOMUP);
        if (oclass==NULL)
            GL_THROW("unable to register object class implemented by %s",__FILE__);

        // publish the class properties
        if (gl_publish_variable(oclass,
            PT_double, "size [cf]", PADDR(size),
            PT_double, "rated_capacity [Btu/h]", PADDR(rated_capacity),
            NULL) < 1)
            GL_THROW("unable to publish properties in %s", __FILE__);

        //setup default values
        defaults = this;
        size = gl_random_uniform(20,40); // cf

        // basic random properties
        thermostat_deadband = gl_random_uniform(2,3);
        Tset = gl_random_uniform(35,39);
        UAr = 1.5+size/40*gl_random_uniform(0.9,1.1);
        UAf = gl_random_uniform(0.9,1.1);
        COPcoef = gl_random_uniform(0.9,1.1);
        
        // size is used to couple Cw and Qrated
        Cf = 8.43 * size/10; // BTU equivalent gallons of water for only 10% of the size of the refigerator
        rated_capacity = BTUPHPW * size*10; // BTU/h

        // duty cycle estimate
        if (gl_random_uniform(0,1)<0.04)
            Qr = rated_capacity;
        else
            Qr = 0;

        // derived properties and other initial conditions
        Tair = gl_random_uniform(Tset-thermostat_deadband,Tset+thermostat_deadband);

        Tout = 59.0;
        power_factor = 0.95;

    }
}

refrigerator::~refrigerator()
{
}

int refrigerator::init(OBJECT *parent)
{
    if (parent==NULL)
    {
        gl_error("refrigerator must have a parent house");
        return 0;
    }
    pHouse = OBJECTDATA(parent,house);

    // attach object to house panel
    pVoltage = (pHouse->attach(OBJECTHDR(this),20,false))->pV;

    // initial demand
    power_kw = rated_capacity*KWPBTUPH;  //stubbed-in default

    return 1;
}

int refrigerator::create() 
{
    memcpy(this, defaults, sizeof(*this));
    return 1;
}


TIMESTAMP refrigerator::sync(TIMESTAMP t0, TIMESTAMP t1) 
{
    double nHours = (gl_tohours(t1)- gl_tohours(t0))/TS_SECOND;

    // sync to house
    Tout = pHouse->get_Tair();

    // compute control event temperatures
    const double Ton = Tset+thermostat_deadband;
    const double Toff = Tset-thermostat_deadband;

    // compute constants
    const double C1 = Cf/(UAr*UAf);
    const double COP = COPcoef*((-3.5/45)*(Tout-70)+4.5);

    // accumulate energy
    kwh_meter = Qr*KWPBTUPH*COP*nHours;
    power_kw = kwh_meter/nHours;

    // process all events
    // change control mode if appropriate
    if (ANE(Qr,0,0.1) && ALT(Tair,Toff,0.1))
        Qr = 0;
    else if (AEQ(Qr,0,0.1) && AGT(Tair,Ton,0.1))
        Qr = rated_capacity;

    // compute constants for this time increment
    const double C2 = Tout - Qr/UAf;

    // determine next internal event temperature
    double Tevent;
    if (AEQ(Qr,0,0.1))
        Tevent = Ton;
    else
        Tevent = Toff;

    // compute time to next internal event
    double t = -log((Tevent - C2)/(Tair-C2))*C1;
    double dt = t;
    if (t==0)
        throw "refrigerator control logic error";

    // if fridge is undersized or time exceeds balance of time or external event pending
    if (t<0 || t>=nHours)
    {
        dt = ((t<0||t>=nHours)?nHours:t);

        // update temperature of air
        Tair = (Tair-C2)*exp(-dt/C1)+C2;
        if (Tair < 32 || Tair > 55)
            throw "refrigerator air temperature out of control";

        return (TIMESTAMP)(t1+dt*3600.0/TS_SECOND);
    }
    // internal event
    else
    {
        Tair = Tevent;
        return TS_NEVER; 
    }
}


// IMPLEMENTATION OF CORE LINKAGE
EXPORT int create_refrigerator(OBJECT **obj, OBJECT *parent)
{
    *obj = gl_create_object(refrigerator::oclass,sizeof(refrigerator));
    if (*obj!=NULL)
    {
        refrigerator *my = OBJECTDATA(*obj,refrigerator);;
        gl_set_parent(*obj,parent);
        my->create();
        return 1;
    }
    return 0;
}

EXPORT int init_refrigerator(OBJECT *obj)
{
    refrigerator *my = OBJECTDATA(obj,refrigerator);
    return my->init(obj->parent);
}

EXPORT TIMESTAMP sync_refrigerator(OBJECT *obj, TIMESTAMP t0)
{
    TIMESTAMP t1 = ((refrigerator*)(obj+1))->sync(obj->clock, t0);
    obj->clock = t0;
    return t1;
}

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