Transformer changing city

[Octavius]

Some time ago I decided that it would be a good idea to connect a city to the power grid. I supplied coal to the power plant, build two transformers and a short stretch of high voltage transmission line and the city, including a dairy and a slaughterhouse I was using at full capacity, received power. Now I could increase the transport of milk, cattle and meat.

But cities grow. In this case, a neighbouring city grew so large that it began to overlap and the transformer came within the limits of both cities. Now it appeared that the transformer suddenly belonged to the neighbouring city and only supplied power to that one. The dairy and slaughterhouse lost power. I could relocate the transformer to the other side of the city, but that's an ugly solution. Somewhere else on my map I have a transformer at the tip of a peninsula. If the neighbouring city grows just a little bit it will be impossible to supply electricity to the city on the peninsula. Although this wouldn't be too bad as all industries are also transferred to the other city and the engulfing city can take over city development.

What would be the best way to solve this problem? I see three logical options. The transformer could stay connected to the city it originally belonged too (but in that case, if you're late building transformers you may have to build awkward transmission lines), or it could be connected to the city with the nearest city hall (my favorite, as it doesn't suddenly double demand), or it could supply power to both cities (might be the most realistic, as in the real world their mid-voltage networks would be interconnected).

[DrSuperGood]

I think power nets as a whole need a revision. Overlapping cities should fuse their power network (representing distribution being installed throughout the entire area including several smaller transformers etc). If that is not desired then transforms inside multiple cities should appear connected to all the cities and power tunnels should have maintenance cost greatly lowered to allow more realistic inner city district distribution of power.

As it is you should avoid using them in multiplayer servers for the time being as they are not fully deterministic so will cause out of sync errors.

[jamespetts]

Overlapping cities are a particular issue that needs careful consideration. Neroden proposed city merging code at one point, and even begun to write it, but that is extremely difficult to do properly, as there are a very large numbers of pointers to cities in arbitrary places which would cause crashes if a city were deleted. The only way to achieve this would be to use a quickstone object instead of a pointer for cities, which would need some fundamental changes made to the code.

[Octavius]

Ah, so it's on the wish list already, but hard to code. I already saw some other power related problems. I've got a paper mill somewhere that draws 70MW, far more than I can deliver in 1915 from the nearby power plants, but by connecting the city the paper mill is automatically connected too, drawing so much power that other industries can't get what they need. And I don't even need to boost production at the paper mill. In the real world the paper mill would not be connected to the city's mid-voltage distribution grid, but would have a direct connection to the high voltage transmission grid.

According to this site (in dutch), 150kV AC transmission lines, which seem to be the ones we simulate in simutrans, are now usually made underground. In the Netherlands at least. They typically carry 300MW. Construction is considerably more expensive than above ground. They don't give any numbers, but say it strongly depends on ground use (build-up areas are expensive, farmland less so, berms are cheapest) and soil type (sand is cheaper than peat, not to mention solid rock, which doesn't exist here). Maintenance however is relatively cheap, as these cables require no maintenance for decades. Said differently, they require no maintenance until they have to be upgraded, meaning replaced. Unless something goes seriously wrong and you can't blame someone else for the damage...

[jamespetts]

Firstly, underground power cables are already implemented in the code ready for the next version (and are present in Standard, too).

Secondly, industries in Simutrans cover everything from corner shops to steel mills. We cannot easily differentiate which is which for electricity consumption purposes: obviously, a corner shop would use a city's electricity network. For simplicity (and because a city's network need not in principle be confined to the domestic and commercial mid-voltage supply in any event), all industries within a city's borders are connected to the grid when the city is connected.

As to there being insufficient production, (1) have you changed your electric_promille setting; and (2) have you supplied all the power stations on the map and connected them to your grid? There should always be enough (indeed, more than enough) electricity generating capacity for all cities and industries, as there is in reality.

[Octavius]

I haven't played standard for a while... I think I have occasionally used underground power cables there, but don't remember the details.

I was thinking of a treshold. If an industry demands more than so many megawatts, it can't be supplied from the city network but the industry needs its own transformer. But a decent treshold would be time dependent, being only a few MW around 1900 and about 70MW nowadays.

And I do have enough electricity, but I had to build an additional 40km of transmission lines including a 1km water crossing using an artificial island to connect a total of 10 power plants to this paper mill, plus 4 new canals (2 of which right through a city) and a new railway to supply coal to these power plants. Slightly inconvenient for a single paper mill that I don't need at full capacity, but part of the fun. Fortunately moving coal by ship is quite profitable. And it may come in handy later.

[Vladki]

I was thinking of a treshold. If an industry demands more than so many megawatts, it can't be supplied from the city network but the industry needs its own transformer. But a decent treshold would be time dependent, being only a few MW around 1900 and about 70MW nowadays.

That sounds reasonable - either a threshold or a dat file option that says - this industry does not use city power - it needs its own transformer. Or, provide a small boost by city power, and extra boost with own transformer - but only for big factories, not shops, those should always use city power.

[DrSuperGood]

A flag would be more meaningful that is set in the data.

"need transformer" (or "energy intensive" if you want something more obscure and less technical)

With the flag ticked the industry gets a 50% power use penalty unless it is connected with a transformer that is connected to the backbone. Additionally it will pay extra for energy used to accommodate the extra transmission costs.

Mechanically distribution transformers connected to an industry should could as connected to all cities that the factory is in and not where the transform is physically located. It should try and pull from the transformer first before from the rest of the city.

However for this to be viable power tunnels need a massive reduction in maintenance to be only 2-3 times more expensive than above ground lines. In real life high voltage under ground cables are not that expensive to maintain, just very expensive to build and also less flexible/easy to use than overhead lines.

[Aquin]

How about making transformers into station like buildings with a supply radius? Bigger cities have more than just one transformer station. So a transformer would not need to care about city limits, and merging and dissapearing cities are no problem.
And maybe there could be a limit on the capacity per transformer, which would allow for distinct types for different applications. Like low throuput, large area ones for the suburbs, 1 field radius infinite throuput ones for heavy industries,...

[jamespetts]

The idea in principle behind the current arrangement is that the city authorities take care of the distribution within cities. This simplifies things for the player: this is, after all, a game primarily about transport rather than electrical distribution. There would be a very great amount of work involved in making the supply of electricity more intricate, and it is doubtful that the opportunity cost in terms of not being able to spend that time developing other features is worth the benefit that it might bring.