Technical Fesability of Underground AC Transmission Cable Grid 3

[Mbrooke]

Cost aside, would it be technically possible to operate an underground transmission grid consisting of solid dielectric cables? Burying all transmission lines 500kv and below on the east coast, west coast, UK or European Union as a discussion reference.

Would shunt reactors at each substation be enough to compensate the immense amount of reactive power? Would switching transients and risks of generator pole slipping make it simply physically impractical?

Somehow I have a feeling there are way more theoretical limitations than I am imagining atm. However, the idea of an entire system 120 volts to 500kv being placed underground with brick GIS substations has an allure to me.

 

[waross]

BC Hydro’s Cathedral Square Park in downtown Vancouver was the first underground substation built in North America, and it has been operating since 1984.

I worked on an expansion of Cathedral in about 1986 or '87.
It is about six stories underground.
As I remember the outgoing voltage was around 13 kV. (Subject to correction)

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

Cathedral Square. A major 230/12 kV urban underground substation. Part 1: Civil and mechanical design features

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Mbrooke]

I will look into this, neat!

I've heard in Canada that substations are disguised as homes.

As much as I like power lines, I have to admit that if everything went underground it would kind of look better- at least I think to the average person who does not care about the look of bushings.

 

[waross]

I've heard in Canada that substations are disguised as homes.

I was not aware of that. Please share any new information.
Back to buried transmission:
Here is a screen shot of a video taken about 70 years ago.
You may see multiple transmission circuits as well as some local distribution along the interurban right-of-way.
Vancouver B.C, First Ave and Slocan street, looking east. Circa 1950

Vancouver B.C, First Ave and Slocan street, Google Maps.

In the next block is the start of a local distribution circuit coming in from the south.
The multiple transmission circuits are now buried under the original ROW.
Here is a link to the video from which the screen shot was taken at 4:37 :[url=https://youtu.be/ZrMEQbeviwo]Link[/url]
Here is a link to Google Maps:Link

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Mbrooke]

To be honest its what I've been told, so its second hand hearsay.

I can't thank you enough for the vid! Wow! Its crazy beautiful hypnotic to see all those circuits and catenary lines on a single pole. That really is something, reminds of modern day California where you have double circuits subtransmission with distro under build.

Any idea if these two videos are related?

https://www.youtube.com/watch?v=y_r1Jh9qrcE

System single line starting at 5:09:

https://www.youtube.com/watch?v=I6XZ-Co4ENk

Anyway, I have to admit that in some ways things look better with everything buried.

 

[waross]

The first video of the Sumas Substation is on the same system as the video that I linked.
Early in the linked video there is a comment that a Chilliwack train could be seen passing. That train would probably have passed the Sumas Substation on the way to Chilliwack.
This was the old B.C.Electric system.
The Greenwood sub is 405 km east in Greenwood B.C.
Greenwood was for many years included in the West Kootenay Power and Light Company system.
However, the substation may have been related to early mining and smelting in the area.
I have no idea if the Greenwood sub was ever used by the West Kootenay Power and Light Company. (Now part of the Fortis Chain.)

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Mbrooke]

Thats so neat!

Any idea of the voltage involved? Was the system interconnected to the main grid? Do you have a map or single line of the old B.C. Electrical system and/or the West Kootenay Power and Light Company? Where the BC and West Kootenay system interconnected in any way?

 

[crshears]

I've heard in Canada that substations are disguised as homes.

True; telephone central offices in urban / suburban areas here [ and occasionally even rural ones ] may be found blended in to the scenery in the same way.

Here's a typical one:

Link >

https://www.google.com/maps/@43.704...4!1sAvV3RdwGugn5J7uH8r15BA!2e0!7i16384!8i8192

Here's a distro station in a residential neighborhood; not quite disguised as a house, but not a typical DS, either:

Link >

https://www.google.com/maps/@42.824...4!1sETzYqD5IXHhz1BH6o4hTUQ!2e0!7i13312!8i6656

I find this to be one of the more aesthetically pleasing transformer station / substation buildings I've seen:

Link >

https://www.google.com/maps/@43.719...4!1s9zU86SM36NtnIyv0pvYHKw!2e0!7i16384!8i8192

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[Mbrooke]

I must admit, those look nice none the less. Mott Haven Substation is a good example:

https://pcims-projects.interactivet...t-profiles-pcims-pc/&pctemplate=one_column_pc

People have mistaken the substation for actual condos.

 

[Mbrooke]

If curious, here is a rough sketch of the system I envision:

Credit sticky:

GIS housed in a brick building, grates for transformer vents, metal doors for equipment replacement.

 

[electricuwe]

The problem is not to build in-door substations, the problem is more the vast amount of capacitive apparent power needed for the high and medium voltage cables. Therefore the length of these cables has to be limited.

The usual approach in Europe is to use HV cable only for radial feeders reaching into the city center from the periphery. These feeders are supplied from a ring of overhead lines in the outer quarters.

This approach combines the benefits of both ways of lines in an optimum way and avoids unnecessary invest (doing all with cable) as well as unacceptable congestion and reliability issues by overhead lines in densely populated areas.

This concept is proven for decades and expect that its use will pertain although some researchers a promoting DC-distribution as alternative.

 

[Mbrooke]

Would reactors at each substation be enough to mitigate this?