Appearance
Pi Line (3-phase)
Three-phase nominal-pi transmission line — series R+L between the two ports plus a C/2 shunt to ground at each end (per phase, no neutral coupling). EMT companion combines the series-RL trapezoidal Norton with two trapezoidal shunt-capacitor companions; load-flow row carries R, X (= ωL), and B (= ωC, total line-charging susceptance, the solver splits half/half between the two ends). Use for medium-length overhead lines or cables where the line-charging current cannot be neglected. For a short line with negligible charging, RLC Branch (3-phase) is simpler. For long cables that require travelling-wave behaviour, use Transmission Line (PI / Bergeron).
Category: Three-Phase / Transmission
Keywords: 3-phase, 3-ph, 3 ph, 3ph, three, three-phase, three phase, phase, ph, pi, PI, nominal, transmission, line, overhead, cable, charging, susceptance, B, load flow, loadflow, EMT, RXB
Ports
| Name | Direction | Value type | Notes |
|---|---|---|---|
i | electrical_3ph | double | |
j | electrical_3ph | double |
Parameters
Config
| Name | Label | Type | Default | Units | Description |
|---|---|---|---|---|---|
r_ohms | R (Ω) | double | 0.5 | — | Per-phase total series resistance (Ω). Drives the EMT series-RL Norton and the load-flow R column (R_pu = R / Z_base, from-bus side). |
l_henries | L (H) | double | 0.01 | — | Per-phase total series inductance (H). Drives the EMT companion and load-flow X (X_pu = ωL / Z_base). |
c_total_farads | C_total (F) | double | 0 | — | Per-phase TOTAL line-charging C (F). EMT splits C/2 at each port; load-flow B column receives the full ωC·Z_base (pu), solver applies B/2 per bus. 0 disables charging (= pure series-RL). |
measure_current | Measure current | enum (Off / On) | 0 | — | Emit per-phase series-branch currents (positive = `i` → `j`). Names on Current Monitoring; blank skips a phase. Shunt-capacitor currents are not published in v1. |
Current Monitoring
| Name | Label | Type | Default | Units | Description |
|---|---|---|---|---|---|
i_name_a | Current name A | string | Ia | — | Observable id for Phase A series-branch current. Blank skips this phase. |
i_name_b | Current name B | string | Ib | — | Observable id for Phase B series-branch current. |
i_name_c | Current name C | string | Ic | — | Observable id for Phase C series-branch current. |
Observables
| Signal | Type | Default name | Enable | Description |
|---|---|---|---|---|
branchCurrent_a | signal | from i_name_a | measure_current | Phase A series-branch current (A). Positive = current flowing from `i` to `j` through the series R+L (excludes the shunt-capacitor charging current at either end). |
branchCurrent_b | signal | from i_name_b | measure_current | Phase B series-branch current (A). |
branchCurrent_c | signal | from i_name_c | measure_current | Phase C series-branch current (A). |
Used in samples
Implemented in C++ class SimCompElecPiLine3ph (components/electrical/sim_comp_elec_pi_line_3ph/sim_comp_elec_pi_line_3ph.h).