Proposed features/Power routing proposal

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Power routing proposal
Status: Draft (under way)
Proposed by: Surly
Tagging: power=circuit
Applies to: Relation Routing context and unify tags for power circuits relations.
Definition: Determine the best tagging model to use to map power circuits all along power grids supported by power=line ways.
Drafted on: 2013-03-11

This proposal is designed to set up a good tagging model and best practices to allow routing on power grids mapped on OSM. It is based upon User icon 2.svg Bahnpirat (on osm, edits, contrib, heatmap)'s work and User icon 2.svg Surly (on osm, edits, contrib, heatmap) point of view published on Power_lines page.

Rationale

As described on many power grid operators' websites, power lines ways don't reflect the real power exchange path. Since OSM uses a relational model to link up path ways, it's possible to define a tagging model to design power circuits as relation between power lines ways on the map.

You may find a little description of how power circuits works on circuits=* page.

Power routing in OSM

Here are the two main point of view which had been expressed on OSM so far. The first one is in favor of type=route + route=power to map circuits since the power exchange is not so different of public transportation networks. The second aim to totally distinguish power routes and transport routes and gives a brand new tagging model.

Tagging similar to Transportation routes

Thus power lines span across the country and electricity always take the shortes way it's transportation behavior is similar to a passenger in a bus. He/She can only travel at the offered routes (physical cable) and it's only possible to change the bus line at bus stops (distribution faccilities). One difference is there are three passengers (phases) which only can travel together (3 cables = 1 electric system) but hate eachother so much, nothing work when they connect (short circuit). ;-) So if 2 systems share the same power tower (6 cables are 2 systems) they have to reach the next power station to meet physicaly. Relation Relations are a good way to show this in OSM. Put every Way way and Area power station connected with this system in one relation and tag as following example shows:

  • type=route
  • route=power
  • wires= (see wires=*)
  • voltage=220000 (no point or colon)
  • operator=XY Corp.
  • cables= (see cables=*, mostly 3 or 6)
  • frequency=50 (for 50 Hertz)

Simple example

Electric-grid-plan.png
Nodes and ways in OSM reflect the physic infrastructure. But is this near enough on reality? Like many lanes of a road are only represented by one Way way, many wires on a power tower are only represented by one Way way in database. But logic infrastructure is more complex. The picture on the left show the difference. A standard relation include all Way ways (lines or cables, may be planned) and Area areas (sub stations), which are directly connected to it.

Way 1, 2, 3

Way 4, 5

Relation blue (members: Way 1,2,3,5 as role line and Area Poldi, Puff, Horntail as role sub_station)

Relation green (members: Way 1,2,3,4 as role line and Area Poldi, Errol, Horntail as role sub_station)

Relation red (members: Way 4,5 as role line and Area Errol, Puff as role sub_station)

Picture and key:value Name in language describtion en Beschreibung de
Relation
type=route
route=power
The route of a system from start to end can be shown with a relation. Like a bus route use streets (highway=*) power systems (=3 cables) using ways (power=line). But changing the line is only possible at stops (power=station)! So it is not possible to change your direction during traveling along the line. To represent these physical fact on a logical map you can use relations. Include all power lines and stations (incl. generator) in the relation and tag it with voltage=*, operator=* etc. These informations are also on the way itself, so relations are only needed in case systems seperate during their journey. Der Verlauf eines Systems vom Start zum Ende kann mit relationen gezeigt werden. Genauso wir Busse die Straßen benutzen, benutzen Systeme die Hochspannungsleitungen. Jedoch kann man nur an Umspannwerken (power=station) umsteigen. Es ist nicht möglich während der Fahrt die Linie zu wechseln. Um diese physikalische tatsache auf einer logischen Karte zu repräsentieren kann man mit Relationen arbeiten. Füge alle Hochspannungsleitungen (ways) und Umspannwerke der Relation hinzu und tagge diese mit voltage=*, operator=* usw. Diese Informationen sind bereits auf der power=line vorhanden, sodass Relationen nur notwendig werden falls sich Systeme in ihrem Verlauf trennen.

Another point of view

Power line routes are not similar to transportation routes. Power lines have exactly two end point and have no "stops" in the middle. The beginning and the end (source and consumer of energy) of the line may exchange sometimes (e.g. in case of emergency switching). A power line may have T-shape connection to another one, but it is not an intermediate stop, it is a beginning of the other line. Also there are no travelling things like buses, passengers or travellers as in "common" routes. A travelling of electrons is rather physical abstraction, and it is not so simple as "small moving balls".

The relation for power circuits must be able, ideally, to tag splitting of phases to individual towers and gathering of them together; circuits T-welding; suppotring structures when part of wire does not transmit electricity but only acts as a holding device.

Among other issues, a special relation will help us not to confuse, when we make a map of transportation routes. Because a map of travelling routes and a map of power lines are different kinds of maps. In case of special relation for power lines a software will not have to analyse the values of route=* (is it equal to "power" or not?) but may rely on a type=route only.

So the structure of this relation is very different from structure of a route relation. That is why we should not tag power circuits with type=route + route=power. We should think about a special relation, and I suggest type=power + power=circuit for this purpose.

example

The folowing drawing illustrates a connection of the substation "H" with two other substations: "K" and "T".

At the substation "H" both of the circuits run on the same towers (line segment 1), then split (the segments 2 and 3). Then the phases of the circuit "H—T" split (4,5,6) and then gather together again (line 7).

Surly power transmission proposal.png

Tagging relations

Relation Relation's tags Relation's members, in the folowing order
Relation Relation for the splitting phases (optional) type=power
power=circuit_segment
Way Ways 4, 5, 6 (in any order)
Relation First circuit's relation type=power
power=circuit
cables=3
ref=H-K
Area polygon of the substation "H" (role substation);
Way ways 1, 2 (role line);
Area polygon of the substation "K" (role substation)
Relation Second circuit's relation type=power
power=circuit
cables=3
ref=H-T
Area polygon of the substation "H" (role substation);
Way way 1, 3 (role line);
Relation relation power=circuit_segment (role line) or, for those who prefer not to use circuit_segment relation: Way ways 4, 5, 6 in any order (role line);
Way way 7 (role line);
Area polygon of the substation "T" (role substation)

Tagging ways and polygons:

Way Area H Area K Area T Way 1 Way 2 Way 3 Way 4 Way 5 Way 6 Way 7
Tags power=substation
ref=H
power=substation
ref=K
power=substation
ref=T
cables=6
circuits=2
cables=3
circuits=1
cables=3
circuits=1
cables=1
circuits=1
phase=L1
cables=1
circuits=1
phase=L2
cables=1
circuits=1
phase=L3
cables=3
circuits=1

Branching

This part of the proposal describes tagging for power line branching. The purpose of this tagging model is to describe which branch circuit, where and to which trunk circuit connects.

Surly power branching proposal.png

The substations "H" and "K" are connected with two power circuits marked as "H-K.1" and "H-K.2". At the line segments 9 and 10 both of the circuits run on the same towers. Towers 1 and 2 are branch pylons where a brach circuits are connected; so trunk circuits at the line segments 3, 4, 5, and 6 run separately. The substation "T" connects to the trunk line with branch circuits marked as "Br.T.1" and "Br.T.2". The circuit "Br.T.1" (segment 7) is connected to the trunk circuit "H-K.1" at the pylon 1, and the circuit "Br.T.2" (segment 8) is connected to the trunk circuit "H-K.2" at the pylon 2. Then both of the branch circuits run on the same towers to the substation "T".

A relation is proposed to describe such branching.

Relation's tag Member Description
type=power Required The relation describes a power network feature
power=branch Required The relation describes a circuit branching
ref=* Optional If the branch is marked with ref number
*=* Optional Any tag that describes the connection itself
Member's role Count Member Description
Relation trunk_circuit One (or zero) Trunk circuit's relation Recommended. May be omitted if the trunk circuit is not mapped with a Relationpower=circuit relation, and Way trunk_line member is recommended in this case.
Relation branch_circuit One (or zero) Branch circuit's relation Recommended. May be omitted if the branch circuit is not mapped with a Relationpower=circuit relation, and Way branch_line member is recommended in this case.
Node via One (or zero) The point (tower) where circuits are connected Recommended. May be omitted if the connection point is unknown or unmapped.
Way trunk_line Zero or more Trunk circuit's line Optional. Recommended if the trunk circuit is not mapped with a Relationpower=circuit relation (because there is no other way to define the line when a relation is absent). May be omitted if the trunk circuit is mapped with a Relationpower=circuit relation (because a line is defined in the relation)
Way branch_line Zero or one Branch circuit's line Optional. Recommended if the branch circuit is not mapped with a Relationpower=circuit relation (because there is no other way to define the line when a relation is absent). May be omitted if the branch circuit is mapped with a Relationpower=circuit relation (because a line is defined in the relation).
example 1

Relation The relation for "H-K.1" circuit:

Tag or role Key Value or member
tag type power
tag power circuit
tag ref H-K.1
tag cables 3
role line Way Ways 9, 3, 5, 10

Relation The relation for "H-K.2" circuit:

Tag or role Key Value or member
tag type power
tag power circuit
tag ref H-K.2
tag cables 3
role line Way Ways 9, 4, 6, 10

Relation The relation for "Br.T.1" circuit:

Tag or role Key Value or member
tag type power
tag power circuit
tag ref Br.T.1
tag cables 3
role line Way Ways 7, 11

Relation The relation for "Br.T.2" circuit:

Tag or role Key Value or member
tag type power
tag power circuit
tag ref Br.T.2
tag cables 3
role line Way Ways 8, 11

Relation The relation for the first connection:

Tag or role Key Value or member
tag type power
tag power branch
role trunk_circuit Relation Relation with ref="H-K.1"
role branch_circuit Relation Relation with ref="Br.T.1"
role via power tower: Node node 1
role trunk_line power line: Way way 3
role trunk_line power line: Way way 5
role branch_line power line: Way way 7

Relation The relation for the second connection:

Tag or role Key Value or member
tag type power
tag power branch
role trunk_circuit Relation Relation with ref="H-K.2"
role branch_circuit Relation Relation with ref="Br.T.2"
role via power tower: Node node 2
role trunk_line power line: Way way 4
role trunk_line power line: Way way 6
role branch_line power line: Way way 8

Comments

Comments are welcome on the talk page :)
Feel free to comment each of schemes described above.

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