Industrial and agricultural loads

Industrial and agricultural loads are implemented using a parametric load model, calculating the real and imaginary current, power, and resistance load components based on the time and existing weather data.

Parametric Loads

Parametric loads can be defined using the pqload object, which is derived from powerflow::load. A pqload object has varying contributions to constant impedance, current, and power depending on prevailing time and weather conditions, such as sunlight, temperature, humidity, wind speed, and rainfall. Each load component (Z, I, P) is nominally computed based on the prevailing weather and adjusted based on the time.

The weather load is computed from a linear transformation as a function of weather as follows:

<math>

\begin{bmatrix} Z_p \\ Z_q \\ I_m \\ I_a \\ P_p \\ P_q \end{bmatrix} = \begin{bmatrix} Zp_T & Zp_H & Zp_S & Zp_W & Zp_R & Zp \\ Zq_T & Zq_H & Zq_S & Zq_W & Zq_R & Zq \\ Im_T & Im_H & Im_S & Im_W & Im_R & Im \\ Ia_T & Ia_H & Ia_S & Ia_W & Ia_R & Ia \\ Pp_T & Pp_H & Pp_S & Pp_W & Pp_R & Pp \\ Pq_T & Pq_H & Pq_S & Pq_W & Pq_R & Pq \end{bmatrix} \ \begin{bmatrix} T_t \\ H_t \\ S_t \\ W_t \\ R_t \\ 1 \end{bmatrix}

</math>

where

• <math>Z</math>, <math>I</math>, <math>P</math> are the constant impedance, current and power components of the load, with <math>_p</math> and <math>_q</math> indicated the real and reactive parts and <math>m</math> and <math>a</math> are the magnitude and angle, respectively;
• <math>T</math> is the outdoor temperature at the time <math>t</math> in °F;
• <math>R</math> is the relative humidity at the time <math>t</math> in %;
• <math>S</math> is the solar gains at the time <math>t</math> in Btu/h;
• <math>W</math> is the wind speed at the time <math>t</math> in mph;
• <math>R</math> is the rainfall at the time <math>t</math> in inch/h;

Properties

The pqload object publishes the following variables, in addition to those published by powerflow::load.

Table 1 - pqload properties

Property	Type	Unit	Default	Description
schedule	char1024	-	* * * * *:1.0;	The load schedule (default is always 1.0)
weather	object	-	NULL	The climate object to use for this load. If NULL, the temperature coefficients will be ignored.
Zp_T	double	ohm/degF	0	Resistance response to temperature
Zp_H	double	ohm/%	0	Resistance response to humidity
Zp_S	double	ohm.h/Btu	0	Resistance response to solar gains
Zp_W	double	ohm/mph	0	Resistance response to wind
Zp_R	double	ohm.h/in	0	Resistance response to rainfall
Zp	double	ohm	∞	Invariant resistance
Zq_T	double	F/degF	0	Capacitance response to temperature
Zq_H	double	F/%	0	Capacitance response to humidity
Zq_S	double	F.h/Btu	0	Capacitance response to solar gains
Zq_W	double	F/mph	0	Capacitance response to wind
Zq_R	double	F.h/in	0	Capacitance response to rainfall
Zq	double	F	0	Invariant capacitance
Im_T	double	A/degF	0	Current magnitude response to temperature
Im_H	double	A/%	0	Current magnitude response to humidity
Im_S	double	A.h/Btu	0	Current magnitude response to solar gains
Im_W	double	A/mph	0	Current magnitude response to wind
Im_R	double	A.h/in	0	Current magnitude response to rainfall
Im	double	A	0	Invariant current magnitude
Ia_T	double	deg/degF	0	Current angle response to temperature
Ia_H	double	deg/%	0	Current angle response to humidity
Ia_S	double	deg.h/Btu	0	Current angle response to solar gains
Ia_W	double	deg/mph	0	Current angle response to wind
Ia_R	double	deg.h/in	0	Current angle response to rainfall
Ia	double	deg	0	Invariant current angle
Pp_T	double	W/degF	0	Real power response to temperature
Pp_H	double	W/%	0	Real power response to humidity
Pp_S	double	W.h/Btu	0	Real power response to solar gains
Pp_W	double	W/mph	0	Real power response to wind
Pp_R	double	W.h/in	0	Real power response to rainfall
Pp	double	W	0	Invariant real power
Pq_T	double	VAr/degF	0	Reactive power response to temperature
Pq_H	double	VAr/%	0	Reactive power response to humidity
Pq_S	double	VAr.h/Btu	0	Reactive power response to solar gains
Pq_W	double	VAr/mph	0	Reactive power response to wind
Pq_R	double	VAr.h/in	0	Reactive power response to rainfall
Pq	double	VAr	0	Invariant Reactive power
input_temp	double	degF	--	Observed temperature. Read only.
input_humid	double	%	--	Observed humidity. Read only.
input_solar	double	Btu/h	--	Observed solar gains. Read only.
input_wind	double	mph	--	Observed wind speed. Read only.
input_rain	double	in/h	--	Observed rainfall. Read only.
output_admit_p	double	Ohm	--	Observed resistance. Read only.
output_admit_q	double	Ohm	--	Observed capacitance. Read only.
output_current_m	double	A	--	Observed current magnitude. Read only.
output_current_a	double	degrees	--	Observed current angle. Read only.
output_power_p	double	W	--	Observed real power. Read only.
output_power_q	double	VAr	--	Observed reactive power. Read only.
output_admittence	complex	Ohm	--	Observed impedance. Read only.
output_current	complex	A	--	Observed complex current. Read only.
output_power	complex	W	--	Observed complex power. Read only.

The schedule is defined based the POSIX standard for crontab. The general syntax is

moh hod dom moy dow[ lpu][; ...]

where

• moh is the minute of hour;
• hod is the hour of day;
• dom is the day of month;
• moy is the month of year;
• dow is the day of week;
• lpu is the load per unit (optional, 1.0 if omitted);

The block may be repeated as many times as needed to complete the schedule. Any unscheduled time interval is assumed to be 0.