Proposed features/Transformer extension proposal

From OpenStreetMap Wiki
Jump to: navigation, search
Transformer extension proposal
Status: Proposed (under way)
Proposed by: fanfouer
Tagging: transformer=*
Applies to: Node Area
Definition: Propose to add extra details about power transformers devices functionalities and specifications
Drafted on: 2017-02-10
RFC start: 2017-07-31
Vote start: 2017-08

Rationale

Power transformers are static devices designed to adapt electricity voltage or intensity in an alternating power network.
The amount of flowing energy through the whole network depends of transformers transfer capabilities.
Gather and know functions and figures about transformers can be a concern for consumers involved in power grid operation or environmental design.
As advanced technical knowledge, mappers may look for a consistent and well described model to guide them when adding such information to OSM.
Currently, the wiki doesn't describe enough tags to know well how each transformer work. They are considered as black boxes with input and output voltages but reality can be more complex actually.
Finally this proposal will help to improve data quality and completeness inside OSM and allow consumers to get a better information on how power infrastructure actually works.

Here is a list of common definitions useful to have in mind :

  • Power Transformer (421-01-01) : A static device, with help of electrical induction between metallic windings, converts a given voltage and current to another voltage and current. The delivery is done at the same frequency.
  • Winding (421-03-01) : An assembly of metallic wire turns forming a circuit associated with one of the voltages of a transformer. Note on a polyphase transformer, a winding is the combination of phase windings. Interfaces are use to be called primary, secondary, tertiary and so on, which will be useful to adapt tagging scheme in this proposal. The number of windings, nor voltage levels aren't limited in theory.
  • Auxiliary transformer (605-02-46) : Transformer exclusively intended to supply the internal circuits of a power substation.
  • Bank (151-12-11) : Set of devices connected and acting together.

Proposal

It is proposed to add extra tags or values to get a better description of power transformer devices :


There is no point to replace or deprecate any reviewed key or value here.

Transformers have been tagged for years in OSM, most of the formal work regarding tags had already been done in the substation refinement proposal. This proposal only complete the existing stuff.
This proposal focus on tags to use if, and only if, data is available. It does not assume all data can be publicly known but provide a consistent model to add it to the map if possible, without any power grid operator help.

Where do I find such data ?

Power transformer datasheet.jpg

First of all, don't go inside power substations if you're not invited to do so please, it's dangerous and probably illegal.
Public information or aerial imagery will help to see outdoor transforming facilities safely.

On every transforming device found (not building, not fence), add a Node and put some tags described below like mandatory power=transformer.
Use location=* to give information about its position and transformer=* to let us know about its function.

High detailed information may be found on transformers themselves. A complete datasheet as exposed beside gives many figures on the machine capabilities and structure.
We basically need voltages, windings structure but manufacturer=* and start_date=* may also be completed.
Nevertheless, you may not be able to took picture of those plates and as a reminder : don't go inside restricted perimeters to get the one you couldn't. unless invited

Tagging

It may be good to complete the transformer=* definition with following value :

List of possible transformer=* values.
Key Value Comment
transformer auxiliary Auxiliary transformers intend to supply power to substation internal systems. They're not feeding any subscriber connected to power grid but act as a load on the substation architecture.

Voltage tagging

Transformers are designed to adapt voltage between their windings connected to interfaces. We use to call them primary, secondary and so on.
Each interface is defined with its own voltage and transformers won't have a global voltage value. This proposal aims to discourage the use of voltage=* without suffix on transformers.
It's proposed to use voltage:primary=*, voltage:secondary=* instead according to the interface's name.

Key Value Description
voltage:primary Primary interface's voltage The operating voltage of a given transformer's primary interface.
voltage:secondary Secondary interface's voltage The operating voltage of a given transformer's secondary interface.
voltage:tertiary Tertiary interface's voltage The operating voltage of a given transformer's tertiary interface.

Windings and interfaces description

Power transformer structural example

Transformers are often composed of simple windings facing each other linked to identical primary and secondary interfaces which is pretty nice to tag with a few keys.
And sometimes, you may find 3-phases single primary winding but two 3-phases secondary windings or whatever arrangement you can imagine.
Those complex situations need extended keys to be accurately described in OSM. phases=* and windings=* may be suffixed with :primary, :secondary, :tertiary... to give as specific values as it needs for a specific interface. If no suffix is used, the values will be considered as common to all interfaces of the transformer.
Even if several windings can compose a single interface, they should operate at the same voltage. If voltage is different, then it's not the same winding/interface.

Let's introduce windings=* also to give the number of windings composing each interface of the transformer.

To describe all interfaces with a single bunch of keys

Key Value Description
phases Phases number For polyphase systems, like national, regional and local power grids, this key gives the number of phases connected to the transformer.
windings Number of windings for the whole transformer This key gives the amount of windings for the whole transformer whatever it's for primary, secondary...
rating Global power rating The power rating going through the transformer, mainly from primary to every other interfaces.

To describe each interface separately, given with 3 interfaces but keys can be suffixed accordingly if more voltage levels needed :

Key Value Description
phases:primary Number of phases composing the primary winding -
phases:secondary Number of phases composing the secondary winding -
phases:tertiary Number of phases composing the tertiary winding -
windings:primary Number of primary windings Amount of polyphase windings connected to the primary interface of the transformer
windings:secondary Number of secondary windings Amount of polyphase windings connected to the secondary interface of the transformer
windings:tertiary Number of tertiary windings Amount of polyphase windings connected to the tertiary interface of the transformer
rating:primary Rating of primary winding Rating of the primary winding only
rating:secondary Rating of secondary winding Rating of the secondary winding only
rating:tertiary Rating of tertiary winding Rating of the tertiary winding only

Transformer sets

3 mono phase transformers on top of a wooden pole

In some situations and countries, polyphase transformers may not be contained in a single box. It's not unusual to find several mono phase transformers boxes assumed as an equivalent to a single polyphase transformer.
This proposal would introduce devices=*, defaults to 1, to indicate how many different boxes you see, sharing the same figures and functions.
It won't be useful to add a transformer: prefix since such a key can be used in many other situations far beyond power field of knowledge.

Such a key will factorise as many features as possible on a same node. Thus, all keys giving figures or functions will have to be valued for a single device.
More example are available below, here the principle : 2 similar three-phase 50Hz transformers may be factorised as this on the same node : devices=2 + phases=3 + frequency=50.

Please note that, according to IEC 151-12-11, such disposal of transformers can't be properly called a bank since transformers aren't connected together but each one connected to a different live cable (or even different power circuit). A set would be more appropriate.

Values to be replaced

Some pretty used tags should be carefully replaced like suggested below.
It's recommended to check the values of such tags and to not mass edit.

Obsolete tag Usage volumetry Used for ? New tag(s) to use
voltage=* ~10 500 on 2017-07-30 Give a list of used voltages on a Nodepower=transformer voltage:primary=* + voltage:secondary=* + ...
voltage-high=* 6 128 on 2017-07-30 Voltage used on a transformer's primary interface voltage:primary=*
voltage-low=* 3 996 on 2017-07-30 Voltage used on a transformer's secondary interface voltage:secondary=*

Examples

Transmission transformers

Photo Aerial view Tagging Note
6kV => 63kV elevation transformer
--

power=transformer
voltage:primary=63000
voltage:secondary=6000
windings=3
windings:primary=1
windings:secondary=2
phases=3
rating=20 MVA
location=outdoor

This transformer intends to stup up 6kV power output from a 2 units hydraulic power plant to the 63kV local power grid.


It has 2 windings as secondary side and a single winding on the primary grid side.

225kV => 63kV + 10kV
--

power=transformer
voltage:primary=225000
voltage:secondary=63000
voltage:tertiary=10000
windings=3
windings:primary=1
windings:secondary=1
windings:tertiary=1
phases=3
rating=70 MVA
location=outdoor

This transformer has 3 windings operating at 3 different voltages. 225kV side is on the foreground while 63kV is hidden at the back


Tertiary winding is dedicated to 10kV, certainly for auxiliary services including transformer cooling system

Distribution transformers

Photo Aerial view Tagging Note
Transformer on power pole
--

power=pole
transformer=distribution
voltage:primary=20000
voltage:secondary=400
windings=2
phases=3

Tranformers can directly be hosted on poles to save ground place and prevent complex infrastructure building when not needed.
Multiple mono phase transformers on a single pole
--

power=pole
transformer=distribution
voltage:primary=20000
voltage:secondary=400
windings=2
devices=3
phases=1

Multiple mono phase transformers used on a 3-phase network
63kV => 20kV
--

power=transformer
voltage:primary=63000
voltage:secondary=20000
windings=2
windings:primary=1
windings:secondary=1
phases=3
location=outdoor
rating=20 MVA

20kV => 15kV autotransformer
--

power=transformer
transformer=auto
voltage:primary=20000
voltage:secondary=15000
windings=2
windings:primary=1
windings:secondary=1
phases=3
location=outdoor

Such transformer are used in France to feed legacy 15kV distribution zones from current 20kV infrastructures.


Visible sign show us operational voltages of both sides and that the transformer works as an auto-transformer.

Traction transformers

Photo Aerial view Tagging Note
225kV => 25kV transformer
--

power=transformer
transformer=traction
voltage:primary=225000
voltage:secondary=25000
windings=2
windings:primary=1
windings:secondary=1
phases=2
location=outdoor

High speed rail lines are fed from transmission power grid with such biphase transformers.
-25kV feeder => 25kV catenary auto-transformers
--

On one of each transformer inside of the substation power=transformer
transformer=traction
voltage:primary=-25000
voltage:secondary=25000
windings=2
windings:primary=1
windings:secondary=1
phases=1
location=outdoor

Due to pretty long distances, high speed rail 25kV catenaries have to be regularly fed by auto-transformers which take power from a -25kV feeder line going along railways.

Auxiliary transformers

Voting

Instructions for voting
  • Log in to the wiki if you are not already logged in.
  • Scroll down to voting and click 'Edit source'. Copy and paste the appropriate code from this table on its own line at the bottom of the text area:
I approve this proposal yes {{vote|yes}} --~~~~
I oppose this proposal no {{vote|no}} reason --~~~~
Replace reason with your reason(s) for voting no.
I abstain from voting but have comments abstain {{vote|abstain}} comments --~~~~
If you want don't want to vote but have comments. Replace comments with your comments.

Note: The ~~~~ automatically inserts your name and the current date.

Voting has not started yet.

See also