Switch

Definition

It represents an ideal switch, a lossless element that connects two buses.

Equations

The associated equations are:

\[\begin{split}\left\{ \begin{aligned} \underline{I_1} &= - \underline{I_2}\\ \underline{V_1} &= \underline{V_2}\\ \end{aligned} \right.\end{split}\]

Available Results

The following results are available for all switches:

Result Accessor	Default Unit	Type	Description
res_potentials	\(V\)	2 complex arrays	The potentials of each phase of the switch
res_currents	\(A\)	2 complex arrays	The currents flowing into each phase of the switch
res_powers	\(V\!A\)	2 complex arrays	The powers flowing into each phase of the switch
res_voltages	\(V\)	2 complex arrays	The phase-to-neutral voltages if the switch has a neutral, the phase-to-phase voltages otherwise

The results with two arrays are for the first and second ends of the switch, respectively. The sense of currents and powers is from the corresponding bus into the switch.

Usage

Here is a switch connecting a constant power load to a voltage source.

import functools as ft
import numpy as np
import roseau.load_flow as rlf

# Two buses
bus1 = rlf.Bus(id="bus1", phases="abcn")
bus2 = rlf.Bus(id="bus2", phases="abcn")

# A line
switch = rlf.Switch(id="switch", bus1=bus1, bus2=bus2)

# A voltage source on the first bus
vs = rlf.VoltageSource(id="source", bus=bus1, voltages=400 / rlf.SQRT3)

# The potential of the neutral of bus1 is fixed at 0V
pref = rlf.PotentialRef(id="pref", element=bus1)

# An unbalanced constant-power load on the second bus
load = rlf.PowerLoad(id="load", bus=bus2, powers=[5000 + 1600j, 2500 + 800j, 0])

# Create a network and solve a load flow
en = rlf.ElectricalNetwork.from_element(bus1)
en.solve_load_flow()

# The current flowing into the switch from bus1
en.res_switches[["current1"]].transform([np.abs, ft.partial(np.angle, deg=True)])
# |                 |   ('current1', 'absolute') |   ('current1', 'angle') |
# |:----------------|---------------------------:|------------------------:|
# | ('switch', 'a') |                    22.7321 |                -17.7447 |
# | ('switch', 'b') |                    11.3661 |               -137.745  |
# | ('switch', 'c') |                     0      |                  0      |
# | ('switch', 'n') |                    19.6866 |                132.255  |

# The current flowing into the switch from bus2
en.res_switches[["current2"]].transform([np.abs, ft.partial(np.angle, deg=True)])
# |                 |   ('current2', 'absolute') |   ('current2', 'angle') |
# |:----------------|---------------------------:|------------------------:|
# | ('switch', 'a') |                    22.7321 |                162.255  |
# | ('switch', 'b') |                    11.3661 |                 42.2553 |
# | ('switch', 'c') |                     0      |                  0      |
# | ('switch', 'n') |                    19.6866 |                -47.7447 |

# The two currents are equal in magnitude and opposite in phase, as expected

# The two buses have the same voltages
en.res_buses_voltages[["voltage"]].transform([np.abs, ft.partial(np.angle, deg=True)])
# |                |   ('voltage', 'absolute') |   ('voltage', 'angle') |
# |:---------------|--------------------------:|-----------------------:|
# | ('bus1', 'an') |                    230.94 |                      0 |
# | ('bus1', 'bn') |                    230.94 |                   -120 |
# | ('bus1', 'cn') |                    230.94 |                    120 |
# | ('bus2', 'an') |                    230.94 |                      0 |
# | ('bus2', 'bn') |                    230.94 |                   -120 |
# | ('bus2', 'cn') |                    230.94 |                    120 |

API Reference

class Switch(id: Id, bus1: roseau.load_flow.models.buses.Bus, bus2: roseau.load_flow.models.buses.Bus, *, phases: str | None = None, geometry: shapely.geometry.base.BaseGeometry | None = None)

Bases: roseau.load_flow.models.branches.AbstractBranch[roseau.load_flow_engine.cy_engine.CySwitch]

A general purpose switch branch.

Switch constructor.

Parameters:

• id – A unique ID of the switch in the network switches.

• bus1 – Bus to connect to the switch.

• bus2 – Bus to connect to the switch.

• phases – The phases of the switch. A string like "abc" or "an" etc. The order of the phases is important. For a full list of supported phases, see the class attribute allowed_phases. All phases of the switch must be present in the phases of both connected buses. By default, the phases common to both buses are used.

• geometry – The geometry of the switch.

element_type: Final = 'switch'

allowed_phases: Final

The allowed phases for a switch are:

• P-P-P or P-P-P-N: "abc", "abcn"

• P-P or P-P-N: "ab", "bc", "ca", "abn", "bcn", "can"

• P or P-N: "a", "b", "c", "an", "bn", "cn"

• N: "n"

property phases: str

The phases of the switch. This is an alias for phases1 and phases2.