Appearance
Transformer (3-phase, 2-winding)
Three-phase two-winding (HV / LV) mutually-coupled transformer. Linear magnetization + leakage only — no saturation, hysteresis, or residual flux. Fixed 3-leg core (shared magnetic circuit blocks zero-sequence flux). Vector-clock phase shift on HV→LV. Optional tap changer (first-order lag toward a tap_cmd named input) on a user-selectable host winding. Carries a load-flow PSSE 2-winding record; the column values are derived from the EMT parameters via the schema's computations block (no separate load-flow tab). Same parameter shape as the 3-winding sibling (transformer_3w_3ph) with the TV side dropped.
Category: Transformers
Keywords: 3-phase, 3-ph, 3 ph, 3ph, three, three-phase, three phase, phase, ph, trafo, TX, tx, winding, 2-winding, two-winding, linear, HV, LV, Y, Yy, Yd, Dy, Dd, wye, delta, star, vector group, tap, tap changer, OLTC, load flow, loadflow
Ports
| Name | Direction | Value type | Notes |
|---|---|---|---|
HV | electrical_3ph | double | |
LV | electrical_3ph | double | |
HV_n | electrical | double | Visible when hv_connection == 'YN' |
LV_n | electrical | double | Visible when lv_connection == 'yn' |
Parameters
Config
| Name | Label | Type | Default | Units | Description |
|---|---|---|---|---|---|
s_rated | S rated | double | 100 | MVA (VA, kVA, MVA) | Three-phase apparent-power rating. The unit selector beside this field lets you enter the value in VA, kVA, or MVA — at netlist-export time the schema's `computations` block converts the selection to canonical VA, which is what the EMT model and load-flow extractor read. Sets the transformer's per-unit base (Z_base_pu = V_LL² / S_rated) and the load-flow R / X system-base conversion (R_pu_sys = R_pu_tx · 100 MVA / S_rated_canonical). |
f_rated_hz | f rated (Hz) | double | 60 | — | Rated electrical frequency, in hertz. Drives every per-unit-to-henries conversion (X_pu → L = X_pu · Z_base / (2πf)) on the EMT side; the load-flow extractor uses the system base frequency (60 Hz) for its own conversions, so f_rated_hz is EMT-only. |
v_hv_rated_v | V HV rated (LL) | double | 230000 | V (V, kV) | HV-winding rated line-to-line RMS voltage. The unit selector beside this field lets you enter the value in V or kV — at netlist-export time the schema's `computations` block converts the selection to canonical volts, which is what the EMT model and load-flow extractor read. Drives the HV-side per-unit base and the HV:LV turns ratio (per-winding rated voltage: V_LL/√3 for Y, V_LL for Δ). Surfaces as load-flow NOMV1 (converted to kV at extract time). |
v_lv_rated_v | V LV rated (LL) | double | 115000 | V (V, kV) | LV-winding rated line-to-line RMS voltage. Pick V or kV in the unit selector; the computations block converts to canonical volts at netlist export. Sets the LV-side per-unit base. Surfaces as load-flow NOMV2. |
hv_connection | HV connection | enum (Y (floating N) / YN (N exposed) / Δ delta) | YN | — | HV winding connection. `Y` = floating-N wye. `YN` = wye with N exposed at the HV_n port (ground externally). `D` = delta. |
lv_connection | LV connection | enum (y (floating n) / yn (n exposed) / d (delta)) | yn | — | LV winding connection. `y` = floating-n wye. `yn` = wye with n exposed at the LV_n port. `d` = delta. |
hv_lv_vector_clock | HV→LV vector clock | enum (0 (in phase) / 1 (−30°) / 5 (−150°) / 6 (180°) / 7 (+150°) / 11 (+30°)) | 0 | — | Phase shift of LV relative to HV, in 30° clock units (0 = in-phase, 1 = LV lags HV 30°, 11 = LV leads 30°, 6 = 180°). Maps directly to PSSE ANG2 = −30° × clock. |
r_hv_lv_pu | R HV-LV (pu) | double | 0.005 | — | HV-LV pair series resistance, per-unit on the transformer's own base (S_rated, V_HV-rated). Measured by short-circuiting LV and energising HV at rated current. Typical 0.002 – 0.01. Split evenly between the HV and LV winding leakages (R_HV_pu = R_LV_pu = R_HV-LV_pu / 2) when stamped on the EMT side. |
x_hv_lv_pu | X HV-LV (pu) | double | 0.1 | — | HV-LV pair leakage reactance, per-unit on the transformer's own base. Typical 0.08 – 0.12. Split evenly between the two windings (X_HV_pu = X_LV_pu = X_HV-LV_pu / 2). Surfaces as PSSE column R / X (after a 100 MVA / S_rated rebase). |
i_mag_hv_pct | I_mag HV (%) | double | 1 | — | No-load magnetizing current on the HV side at rated voltage, in percent of HV rated current (= 100 × I_mag / I_HV_rated). Sets the linear magnetizing inductance referred to the HV winding (the model uses HV as the magnetisation reference). |
i_mag_lv_pct | I_mag LV (%) | double | 1 | — | No-load magnetizing current on the LV side at rated voltage, in percent of LV rated current. Informational in v1 — the LV magnetisation contribution is implied by the per-pair leakages and the HV-side L_m. Round to the same value as i_mag_hv_pct if you have no separate measurement. |
no_load_loss_pu | No-load loss (pu) | double | 0 | — | No-load (iron) loss, per-unit on S_rated. Lumps hysteresis + eddy at f_rated. The `No-load loss topology` parameter below picks where the resulting conductance is stamped. Set to 0 to disable. |
no_load_loss_topology | No-load loss topology | enum (Across HV winding / Line-to-ground per phase) | winding | — | Where the no-load-loss conductance is stamped. `winding`: in parallel with the HV magnetising branch (across the per-leg HV winding). `line_ground`: as a shunt from each HV line terminal to ground (3-phase Y of conductors, common for surge / lightning models). |
enable_tap_changer | Tap changer | enum (Off / On) | 0 | — | Enable the named-input-driven tap. When 0, the host winding's turns ratio is the rated value and `tap_cmd` is ignored. When 1, the schema surfaces the Tap Changer tab and resolves the `tap_cmd` named input — the host winding's effective ratio tracks `tap_cmd` through a first-order lag with time constant `tap_time_constant_s` (initial value `tap_init_pu`). |
measure_hv_current | Measure HV current | enum (Off / Line current / Winding current) | off | — | Emit HV per-phase currents. `off`: do not emit. `line`: per-phase line current (current into the HV port — coincides with winding current for Y connection). `winding`: per-phase winding current (line current rotated into the Δ winding for D connection; same as line for Y). |
measure_lv_current | Measure LV current | enum (Off / Line current / Winding current) | off | — | Emit LV per-phase currents. Same options as `Measure HV current`. |
measure_mag_current | Measure mag current | enum (Off / On) | 0 | — | Emit per-leg magnetizing current i_mag_a/b/c (A) through the linear magnetising branch. |
Tap Changer
| Name | Label | Type | Default | Units | Description |
|---|---|---|---|---|---|
tap_host_winding | Host winding | enum (HV / LV) | hv | — | Which winding's turns ratio the tap modulates. Only that winding's WINDV column in the load-flow record deviates from 1.0; the other stays at nominal. |
tap_time_constant_s | Time constant (s) | double | 1 | — | First-order time constant (seconds) used to ramp the host winding's effective ratio toward `tap_cmd` after each step. The EMT model applies the lag exp(-h/τ) per step. |
tap_init_pu | Initial ratio (pu) | double | 1 | — | Initial value of the host winding's effective ratio at t = 0, in pu of rated voltage. 1.0 = nominal turns. Also seeds the load-flow WINDV column on the host winding. |
tap_cmd_signal_name | Tap signal name | string | tap | — | Name of the published signal that drives the tap command (in pu of nominal). The named input is always 1-step delayed via MemoryArena.prev — no algebraic-loop risk even when the source transitively depends on this transformer's voltage. Leave empty to disable the binding (the lag still runs from the initial value). |
Monitoring
| Name | Label | Type | Default | Units | Description |
|---|---|---|---|---|---|
i_hv_name_a | HV name A | string | I_HVa | — | Observable id for the HV-side Phase A current. Blank skips this phase. |
i_hv_name_b | HV name B | string | I_HVb | — | Observable id for the HV-side Phase B current. |
i_hv_name_c | HV name C | string | I_HVc | — | Observable id for the HV-side Phase C current. |
i_lv_name_a | LV name A | string | I_LVa | — | Observable id for the LV-side Phase A current. |
i_lv_name_b | LV name B | string | I_LVb | — | Observable id for the LV-side Phase B current. |
i_lv_name_c | LV name C | string | I_LVc | — | Observable id for the LV-side Phase C current. |
i_mag_name_a | Mag name A | string | ImagA | — | Observable id for the Phase A magnetising current. |
i_mag_name_b | Mag name B | string | ImagB | — | Observable id for the Phase B magnetising current. |
i_mag_name_c | Mag name C | string | ImagC | — | Observable id for the Phase C magnetising current. |
Observables
| Signal | Type | Default name | Enable | Description |
|---|---|---|---|---|
i_HV_a | signal | from i_hv_name_a | measure_hv_current | HV-side Phase A current (A). `line` mode reports the current into the HV_a port; `winding` mode reports the current through the HV winding (rotated to the Δ winding loop for D connection). |
i_HV_b | signal | from i_hv_name_b | measure_hv_current | |
i_HV_c | signal | from i_hv_name_c | measure_hv_current | |
i_LV_a | signal | from i_lv_name_a | measure_lv_current | |
i_LV_b | signal | from i_lv_name_b | measure_lv_current | |
i_LV_c | signal | from i_lv_name_c | measure_lv_current | |
i_mag_a | signal | from i_mag_name_a | measure_mag_current | |
i_mag_b | signal | from i_mag_name_b | measure_mag_current | |
i_mag_c | signal | from i_mag_name_c | measure_mag_current |
Used in samples
Implemented in C++ class SimCompElecTransformer2w3ph (components/electrical/sim_comp_elec_transformer_2w_3ph/sim_comp_elec_transformer_2w_3ph.h).