PQ Load (3-phase)

Three-phase static load carrying both an EMT voltage-dependent model AND a load-flow PL/QL row. The load_type selects how the drawn P and Q vary with the terminal voltage V around the nominal V_nom: Constant Power (P,Q held), Constant Current (P,Q ∝ V), Constant Impedance (P,Q ∝ V²), or ZIP (a polynomial blend P = P₀·[Zp·u² + Ip·u + Pp], u = V/V_nom, six independent fractions for P and Q). The EMT side is modelled as a per-phase parallel conductance G(V) and inductance L(V) to ground; the per-step terminal RMS voltage is tracked over a 1/f window and the non-impedance terms are re-injected as a Norton correction each step. A low-voltage cutoff reverts the constant-power / constant-current terms to constant-impedance below v_cutoff_pu so the draw stays finite during faults. The load-flow side stays a textbook constant-power PL/QL model; the two converge exactly when the solved bus voltage equals v_nom_v. Optional per-phase current monitoring and a low-pass-filtered P/Q monitor (Akagi instantaneous power, user-selectable units) publish observables. An optional in-line breaker (a ganged 3-pole switch) can disconnect the load from the bus, driven either by a list of toggle times or by a named command signal; its initial state is drawn on the canvas.

Category: Three-Phase / Passive

Ports

Name	Direction	Value type	Notes
bus	electrical_3ph	double

Parameters

Config

Name	Label	Type	Default	Units	Description
p_w	P	double	10	MW (W, kW, MW)	3-phase real-power demand at V_nom. Pick a unit from the dropdown (stored canonically in watts). Drives the load-flow PL column and the EMT model's nominal real draw. Positive = drawn from the bus.
q_var	Q	double	3	MVAr (VAr, kVAr, MVAr)	3-phase reactive-power demand at V_nom. Pick a unit from the dropdown (stored canonically in vars). Positive = inductive (L > 0); negative = capacitive (v1 EMT collapses |Q| to inductive with a warning). Drives QL and the EMT susceptance.
v_nom_v	V nom (LL)	double	13800	V (V, kV, pu)	Line-to-line RMS voltage at which (P, Q) are specified. Pick a unit from the dropdown (stored canonically in volts); pu multiplies by V_base from the Units tab. The EMT voltage-dependence ratio is u = |V| / V_nom; EMT and PF match exactly when |V| = V_nom.
f_rated_hz	f rated	double	60	—	System frequency (Hz). Sizes the equivalent inductance (L = X / 2πf) and the 1/f window used to track the terminal RMS voltage for the voltage-dependence.
load_type	Load type	enum (Constant Power (P) / Constant Current (I) / Constant Impedance (Z) / ZIP)	impedance	—	How the drawn P and Q vary with terminal voltage V (u = V/V_nom). Constant Power: P,Q held flat (∝ u⁰). Constant Current: P,Q ∝ u. Constant Impedance: P,Q ∝ u² (fixed admittance — the legacy model). ZIP: polynomial blend P₀·[Zp·u² + Ip·u + Pp] with six independent Z/I/P fractions on the ZIP tab.
v_cutoff_pu	Low-V cutoff (pu)	double	0.7	—	Below this voltage (per-unit on V_nom) the constant-power and constant-current terms revert to constant impedance so the current draw stays finite during deep sags / faults (I ∝ 1/V would otherwise diverge as V→0). Constant-impedance loads ignore this. Typical 0.6–0.8.
measure_current	Measure current	enum (Off / On)	0	—	Emit per-phase load currents (positive = into the load) as observables. Names on the Current Monitoring tab; blank skips a phase.
monitor_pq	Monitor P/Q	enum (Off / On)	0	—	Emit measured real (P) and reactive (Q) power drawn by the load as observables. Uses the instantaneous Akagi form, low-pass filtered with the time constant on the Power Monitoring tab to reject 2ω ripple. Names and units on the Power Monitoring tab.
breaker	Breaker	enum (None / Time Triggered / Signal Triggered)	0	—	Optional in-line breaker between the bus terminal and the load (a ganged 3-pole switch — all three phases open/close together). None: the load is permanently connected. Time Triggered: the breaker toggles open↔closed at each time listed on the Breaker tab. Signal Triggered: a named signal commands the breaker (> 0 = closed, ≤ 0 = open). While the breaker is open the load is disconnected from the bus (draws ~0 current); load-flow P/Q is unaffected by the breaker.
breaker_initial_state	Initial state	enum (Open / Closed)	1	—	Breaker state at t = 0, and the symbol drawn on the canvas (Closed = arm bridges the contacts, load connected; Open = arm lifted, load disconnected). For Time Triggered this is the state before the first trigger time; for Signal Triggered it holds for the first step until the command signal is read.

Breaker

Name	Label	Type	Default	Units	Description
breaker_times	Trigger time(s)	string	(empty)	—	Comma-separated trigger times in seconds, e.g. `2` or `2,4,6`. The breaker toggles state (open↔closed) at each time, starting from the Initial state. Blank = never toggles (the breaker stays at the Initial state for the whole run).
breaker_signal_name	Trigger signal	string	(empty)	—	Name of a published signal that commands the breaker: > 0 = closed, ≤ 0 = open. Resolved by name through the same registry as a GoTo output, a labelled wire, or another component's observable, and read 1-step delayed. Blank holds the breaker at the Initial state.
breaker_state_name	Breaker state name	string	(empty)	—	Optional. Name for an observable reporting the breaker state (1 = closed, 0 = open) so it can be plotted. Blank = not published.

ZIP

Name	Label	Type	Default	Units	Description
zp_frac	Zp (real, ∝V²)	double	1	—	Constant-impedance fraction of the REAL power. The three real fractions Zp + Ip + Pp are normalised to sum to 1 internally.
ip_frac	Ip (real, ∝V)	double	0	—	Constant-current fraction of the REAL power.
pp_frac	Pp (real, ∝V⁰)	double	0	—	Constant-power fraction of the REAL power.
zq_frac	Zq (react, ∝V²)	double	1	—	Constant-impedance fraction of the REACTIVE power. The three reactive fractions Zq + Iq + Pq are normalised to sum to 1 internally.
iq_frac	Iq (react, ∝V)	double	0	—	Constant-current fraction of the REACTIVE power.
pq_frac	Pq (react, ∝V⁰)	double	0	—	Constant-power fraction of the REACTIVE power.

Current Monitoring

Name	Label	Type	Default	Units	Description
i_name_a	Current name A	string	Ia	—	Signal name for Phase A load current.
i_name_b	Current name B	string	Ib	—	Signal name for Phase B load current.
i_name_c	Current name C	string	Ic	—	Signal name for Phase C load current.

Power Monitoring

Name	Label	Type	Default	Units	Description
pq_time_constant	P/Q filter τ (sec)	double	2	—	Low-pass filter time constant for the measured P and Q. Smaller tracks transients; larger gives a cleaner steady-state but slower response. Default 2 s rejects 50/60 Hz ripple strongly. Set 0 for the raw instantaneous values.
p_signal_name	P signal name	string	P	—	Signal name for the filtered real power P drawn by the load. Blank = skip.
p_monitor_unit	P unit	enum (W / kW / MW)	MW	—	Unit the published P observable is scaled to.
q_signal_name	Q signal name	string	Q	—	Signal name for the filtered reactive power Q drawn by the load. Blank = skip.
q_monitor_unit	Q unit	enum (VAr / kVAr / MVAr)	MVAr	—	Unit the published Q observable is scaled to.

Units

Name	Label	Type	Default	Units	Description
V_base	V_base (kV)	double	230	—	Base RMS line-to-line voltage in kV. Used by `pu` impedance / admittance conversions in this component's `computations` block.

Observables

Signal	Type	Default name	Enable	Description
branchCurrent_a	signal	from i_name_a	measure_current	Phase A load current (A). Positive = current drawn from the bus into the load.
branchCurrent_b	signal	from i_name_b	measure_current	Phase B load current (A).
branchCurrent_c	signal	from i_name_c	measure_current	Phase C load current (A).
p_filtered	signal	from p_signal_name	monitor_pq	Measured real power P drawn by the load. Sum of instantaneous v·i across the three phases, low-pass filtered with τ = pq_time_constant, scaled to the chosen P unit (W / kW / MW).
q_filtered	signal	from q_signal_name	monitor_pq	Measured reactive power Q drawn by the load. Akagi instantaneous reactive power (1/√3)·(v_bc·i_a + v_ca·i_b + v_ab·i_c), low-pass filtered with τ = pq_time_constant, scaled to the chosen Q unit (VAr / kVAr / MVAr). Positive = inductive.
breaker_state	signal	from breaker_state_name	breaker	Breaker state: 1 = closed (load connected), 0 = open (load disconnected). Only meaningful when a breaker is enabled.