Voltage Source (3-phase)

Three-phase voltage source with a configurable Thévenin impedance topology (Ideal / R resistor / R-L series / R∥L parallel / R-R∥L), optional zero-sequence neutral grounding impedance (R-L or R∥L) on Y (gnd N) AND Y (ext N) connections, optional harmonic injection (up to five terms), and optional P/Q monitoring (measured either at the terminal or at the internal EMF) with a user-configurable low-pass filter time constant. Monitored quantities carry their own unit selectors: per-phase current (A / kA), P (W / kW / MW), and Q (VAr / kVAr / MVAr). Generates a balanced fundamental sinusoid (configurable amplitude, frequency, and phase reference). The Impedance tab exposes R (series) and R (parallel) independently — the topology selector enables only the relevant one(s). Inductors accept H, pu, or X (Ω at the source's own frequency). Each impedance / zero-sequence parameter carries its own unit selector; the auto-injected Units tab carries V_base / S_base when any pu selection is in use (frequency is taken from this source's frequency parameter).

Category: Three-Phase / Sources

Ports

Name	Direction	Value type	Notes
bus	electrical_3ph	double
n	electrical	double	Visible when connection == 'external_neutral'

Parameters

Config

Name	Label	Type	Default	Units	Description
voltage	V_mag	double	230	kV (V, kV, pu)	Fundamental line-to-line RMS voltage. Each phase is driven at V_LN_peak = V_LL_rms·√(2/3); the 120° offset is applied internally.
frequency	f	double	60	—	Fundamental frequency (Hz). Drives the sinusoid generator and the pu → henries conversion when inductive elements are entered in pu.
phase	V_ang	double	0	deg (deg, rad)	Phase A reference angle. B / C apply the 120° offset (sign from `sequence`). Degrees or radians via the unit dropdown.
connection	Connection	enum (Y (ext N) / Y (int N) / Y (gnd N) / Δ (delta))	internal_neutral	—	Winding connection. `Y (ext N)` exposes the star point N via the `n` port (directly, or through Z_n if set). `Y (int N)` floats N internally. `Y (gnd N)` ties N to ground (optionally via Z_n). `Δ` is delta — no neutral.
sequence	Sequence	enum (ABC (+) / ACB (-))	ABC	—	Phase sequence: ABC (positive) or ACB (negative).
waveform	Waveform	enum (AC / Harmonics)	ac	—	Pure sinusoidal AC, or AC + user-defined harmonics. Picking `harmonics` reveals the Harmonics tab.
impedance_type	Impedance	enum (Ideal / R / R-L / R∥L / R-R∥L)	R-L	—	Per-phase Thévenin impedance between EMF and bus. `Ideal` = stiff source. `R` = pure resistor (no inductance). `R-L` = series R+L. `R∥L` = parallel R+L. `R-R∥L` = pre-series R then a parallel R∥L. Fields appear on the Impedance tab; entering 0 drops that element.
zero_seq_type	Zero-Seq Z	enum (None / R-L / R∥L)	none	—	Neutral-grounding impedance Z_n between N and the neutral terminal (ground in `gnd N`, the `n` port in `ext N`). `None` = direct tie. `R-L` = series R+L. `R∥L` = parallel R∥L. Active for `gnd N` / `ext N`.
ramp_time	t_ramp	double	0	—	Voltage ramp-up time (s). Amplitude scales 0 → full linearly over `t_ramp`, then holds. Use ~1 fundamental period on HV sources to avoid t=0 inrush. 0 disables.
measure_current	Measure current	enum (Off / On)	0	—	Emit per-phase source branch current as observables. Names live on the Signal Names tab.
monitor_pq	Monitor P/Q	enum (Off / On)	0	—	Emit real (P, W) and reactive (Q, VAR) power as observables. Uses the instantaneous Buchholz / Akagi form, low-pass filtered with `pq_time_constant` to reject 2ω ripple. Names on the Signal Names tab.
pq_time_constant	P/Q filter τ (sec)	double	2	—	Low-pass filter time constant for P/Q. Smaller tracks transients; larger gives a cleaner steady-state but slower response. Default 2 s rejects 50/60 Hz ripple by ~50 dB.
pq_location	P/Q measured at	enum (Terminal / Internal source)	terminal	—	Where the P/Q monitor reads voltage. `Terminal` uses the solved bus voltage (power delivered into the network at the source's terminals). `Internal source` uses the internal EMF behind the Thévenin impedance (the total power the source generates) — the difference between the two is the I²R / I²X loss in the source impedance. With `Ideal` impedance the two coincide.

Impedance

Name	Label	Type	Default	Units	Description
r_parallel	R (parallel)	double	0.001	physical (Ω, pu)	Parallel resistive element of the Thévenin impedance. Active for `R∥L` (the parallel R) and `R-R∥L` (the inner parallel R; see `R (series)` for the pre-series resistor). Set 0 to short the parallel branch (the topology then collapses to the L-only or R-pre-only case). Independent Ω / pu selector.
l_main	L	double	0	physical (H, Ω, pu)	Inductive Thévenin element. `R-L` series L; `R∥L` parallel L; `R-R∥L` inner parallel L. Pick the unit: H (henries), Ω (reactance at this source's `frequency`), or pu (X_pu on V_base / S_base — the source's own `frequency` is used; no extra frequency input required). 0 drops the element.
r_series	R (series)	double	0.001	physical (Ω, pu)	Series resistive element of the Thévenin impedance. Active for `R` (the sole resistor), `R-L` (the series R between EMF and bus) and `R-R∥L` (the pre-series resistor: EMF → R(series) → R∥L → bus). Set 0 to drop the element. Independent Ω / pu selector.

Zero-Sequence

Name	Label	Type	Default	Units	Description
r_zero	R₀	double	0.001	physical (Ω, pu)	Resistive element of Z_n (neutral-grounding impedance). `R-L` series R; `R∥L` parallel R. 0 drops the element. Independent Ω / pu selector.
l_zero	L₀	double	0	physical (H, Ω, pu)	Inductive element of Z_n. Pick the unit: H (henries), X (Ω, reactance at this source's `frequency`), or pu (X_pu on V_base / S_base — the source's own `frequency` is used). 0 drops the element.

Harmonics

Name	Label	Type	Default	Units	Description
num_harmonics	Number of harmonics	enum (None / 1 / 2 / 3 / 4 / 5)	0	—	Extra harmonic terms (1-5) added to the fundamental. Each k contributes mag·sin(kωt + angle + k·offset_i). Triplens are co-phasal; 5 rotates backward; 7 forward.
h1_order	h1 order	int	3	—	Harmonic order (integer multiple of f). Common: 3 (triplen), 5 (-), 7 (+).
h1_magnitude	h1 magnitude (% of V_mag)	double	0	—	Magnitude as % of V_mag (5.0 = 5%).
h1_angle	h1 angle (deg)	double	0	—	Extra phase angle (deg), added to the per-phase 120° × order offset.
h2_order	h2 order	int	5	—
h2_magnitude	h2 magnitude (% of V_mag)	double	0	—
h2_angle	h2 angle (deg)	double	0	—
h3_order	h3 order	int	7	—
h3_magnitude	h3 magnitude (% of V_mag)	double	0	—
h3_angle	h3 angle (deg)	double	0	—
h4_order	h4 order	int	11	—
h4_magnitude	h4 magnitude (% of V_mag)	double	0	—
h4_angle	h4 angle (deg)	double	0	—
h5_order	h5 order	int	13	—
h5_magnitude	h5 magnitude (% of V_mag)	double	0	—
h5_angle	h5 angle (deg)	double	0	—

Signal Names

Name	Label	Type	Default	Units	Description
current_name_a	Phase A current name	string	Ia	A (A, kA)	Signal name for Phase A branch current. Blank = skip this phase. Pick the unit from the dropdown; the published value is scaled to it.
current_name_b	Phase B current name	string	Ib	A (A, kA)	Signal name for Phase B branch current. Blank = skip this phase. Pick the unit from the dropdown; the published value is scaled to it.
current_name_c	Phase C current name	string	Ic	A (A, kA)	Signal name for Phase C branch current. Blank = skip this phase. Pick the unit from the dropdown; the published value is scaled to it.
p_signal_name	P signal name	string	P	MW (W, kW, MW)	Signal name for filtered real-power P. Blank = skip. Pick the unit from the dropdown; the published value is scaled to it.
q_signal_name	Q signal name	string	Q	MVAr (VAr, kVAr, MVAr)	Signal name for filtered reactive-power Q. Blank = skip. Pick the unit from the dropdown; the published value is scaled to it.

Power Flow

Name	Label	Type	Default	Units	Description
pf_p_mw	Pset (MW)	double	0	—	Scheduled real-power setpoint (MW). PSSE GENERATOR PG column. Positive = inject. Used by the solver as the real-power schedule on a PV or PQ bus; ignored on a slack bus (the source swings to balance the system). Power-flow only — separate from the EMT settings on Config. The regulated voltage is NOT set here: it comes from the connected bus's voltage (set on the bus, by type — slack / PV).
pf_q_mvar	Qset (MVAr)	double	0	—	Scheduled reactive-power setpoint (MVAr). PSSE GENERATOR QG column. Positive = inject (over-excited). Used by the solver as the reactive-power schedule on a PQ bus; on a PV bus Q is solved (this is only a starting estimate), and on a slack bus it is ignored (the source swings).
pf_p_solved_mw	P (MW)	double	0	—	Solved real-power output (MW) from the most recent load flow — the source's actual dispatch, written by 'Apply load-flow results'. Read-only result: overwritten on the next apply, and not exported to PSSE (the schedule lives in Pset).
pf_q_solved_mvar	Q (MVAr)	double	0	—	Solved reactive-power output (MVAr) from the most recent load flow — the source's actual dispatch, written by 'Apply load-flow results'. Read-only result: overwritten on the next apply, and not exported to PSSE (the schedule lives in Qset).

Units

Name	Label	Type	Default	Units	Description
S_base	S_base (MVA)	double	100	—	System base apparent power in MVA. Used by `pu` impedance / admittance conversions in this component's `computations` block.
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 current_name_a	measure_current	Phase A source branch current, scaled to the chosen current unit (A / kA).
branchCurrent_b	signal	from current_name_b	measure_current	Phase B source branch current, scaled to the chosen current unit (A / kA).
branchCurrent_c	signal	from current_name_c	measure_current	Phase C source branch current, scaled to the chosen current unit (A / kA).
p_filtered	signal	from p_signal_name	monitor_pq	Source real-power output P. Sum of instantaneous v_LN·i across the three phases, low-pass filtered with τ = pq_time_constant, scaled to the chosen P unit (W / kW / MW). v_LN is the terminal bus voltage (`pq_location = terminal`) or the internal EMF behind the Thévenin impedance (`pq_location = source`).
q_filtered	signal	from q_signal_name	monitor_pq	Source reactive-power output Q. Buchholz / 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). The v_ab/v_bc/v_ca are formed from the terminal bus voltage (`pq_location = terminal`) or the internal EMF (`pq_location = source`).

Used in samples

• SimpleAC