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 System-users-3.svgBahnpirat (on osm, edits, contrib, heatmap)'s work and System-users-3.svgSurly (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

This method of tagging should be deprecated. To save the history the description of this method is moved to the special page.

Tagging power circuits with a relation

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; T-shaped circuits connections; 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.

Tagging: a simple case

Relation

A relation of this type collects power line ways that constitute the same power circuit, with the same electrical characteristics, name and reference mark.

Key Value Mandatory? Comment
type power Mandatory category of relations
power circuit Mandatory power circuit routing
ref * Recommended Reference number, name, signature or another naming of the circuit
name *
short_name *
voltage * Recommended Electrical characteristics of the circuit
frequency *
cables *
wires *

Members

Member's role Member's type Count Mandatory? Member Description
line Way one or more Recommended Power line An element of the power line
endpoint Node Way Area Relation 0, 1, 2 Recommended Terminal object A substation, a power tower, or another device where the circuit starts / ends

example (simple case)

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 First circuit's relation type=power
power=circuit
cables=3
ref=H-K
Area polygon of the substation "H" (role endpoint);
Way ways 1, 2 (role line);
Area polygon of the substation "K" (role endpoint)
Relation Second circuit's relation type=power
power=circuit
cables=3
ref=H-T
Area polygon of the substation "H" (role endpoint);
Way way 1, 3 (role line);
Way ways 4, 5, 6 in any order (role line);
Way way 7 (role line);
Area polygon of the substation "T" (role endpoint)

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

Advanced cases: splitting phases

We can explicitly designate where the phases of a circuit split and then gather together again.

This tagging is optional. It may help a software to understand that the cables run in parallel, not in a "shuttle-like" manner. If a software is clever enough to recognize such parallel lines, it will not need this hint.

Relation

Key Value Mandatory? Comment
type power Mandatory category of relations
power circuit_segment Mandatory parallel lines of a power circuit

Members

Member's role Member's type Count Mandadtory? Member Description
line (or empty) Way one or more Recommended Element of the power line One of the parallel elements of the power line

example (splitting phases case)

Consider the same power network as in the simple case.

Tagging relations

Relation Relation's tags Relation's members, in the folowing order
Relation Relation for the splitting phases 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 endpoint);
Way ways 1, 2 (role line);
Area polygon of the substation "K" (role endpoint)
Relation Second circuit's relation type=power
power=circuit
cables=3
ref=H-T
Area polygon of the substation "H" (role endpoint);
Way way 1, 3 (role line);
Relation relation power=circuit_segment (role line);
Way way 7 (role line);
Area polygon of the substation "T" (role endpoint)

Advanced cases: 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. A relation is proposed to describe such branching.

Relation

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

Members

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 (the way closest to the connection) 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 (the way closest to the connection) 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 (branching case)

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".

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
role endpoint Area Substation "H", Area Substation "K"

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
role endpoint Area Substation "H", Area Substation "K"

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
role endpoint Area Substation "T", Node Tower 1

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
role endpoint Area Substation "T", Node Tower 2

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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