Switch

Definition

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

Switch diagram

Equations

The associated equations are:

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

Example

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
un = 400 / np.sqrt(3)
voltages = un * np.exp([0, -2j * np.pi / 3, 2j * np.pi / 3])
vs = rlf.VoltageSource(id="source", bus=bus1, voltages=voltages)

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

# A 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 line from bus1
en.res_branches[["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 line from bus2
en.res_branches[["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: int | str, bus1: Bus, bus2: Bus, *, phases: str | None = None, geometry: BaseGeometry | None = None)

Bases: AbstractBranch

A general purpose switch branch.

Switch constructor.

Parameters:

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

  • 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.

allowed_phases: Final = frozenset({'a', 'ab', 'abc', 'abcn', 'abn', 'an', 'b', 'bc', 'bcn', 'bn', 'c', 'ca', 'can', 'cn', 'n'})

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.