classification of Electric Power Systems

[honglien]

Hi all of you!
I am living in a non native English speaker. In my country, English is used, as all over the world, spreadly. But, using English for thesaurus is so difficult. I have some problems when reading you comments on the forum, reading engineering books, to find the equivalent meaning words in our language, especially, in Electric Power Systems (EPS).
In our country, the classifcation of EPS is depend on the Voltage level. I dont know how to call the EPS in English for the voltage level:
- 500kV?
- 220kV?
- 110kV?
- from 6kV to 35kV?
- under 1000V?
I hope you could hepl me to definite the EPS which the Voltage level above.
Thank you in advance!

 

[slavag]

As I know:
500kV is HV, ultra high voltage.
220,110kV are HV, high voltage.
6-36kV are MV, medium voltage.
<1kV is low voltage.
I don't remember exactly ranges, but are something like to:
up to 50V is very low voltage.
from 50 up to 1000V is LV low voltage
from 1kV up to about 50kV is MV medium voltage.
from 50kV up to 800kV is HV high voltage.
from 800kV up to 1000kV EHV extra high voltage.
from 1000kV AC and 800V DC up to .. is UHV ultra high voltage
Best Regards.
Slava

 

[Zogzog]

For equipment ratings (Red book)

LV - <600V
MV - 601-69kV
HV - 69kV-230kV
EHV -230kV-800kV
UHV - >800kV

 

[QBplanner]

From Planning point of view

- 500kV? Bulk transmission system
- 220kV? Regional transmission system
- 110kV? Regional transmission system
- from 6kV to 35kV? Distribution system
- under 1000V? ??

 

[honglien]

Thank you alot for your replies. they are so heplful to me.
But I still wonder how to understand definitions on EPS from planning poit of view, as QBplanner commented. As reading books, i found some concepts: Transmission System, Sub-Transmission system,Distribution System, Supply Networks, Utility System(Network), Facility System(Network).
I would like you to hepl me:
"Is there any standards (or Recommendations)for above concepts?"
Thank you so much!

 

[waross]

Reactive voltage drop due to line reactance is often the limiting factor on the amount of power a line may transmit at a given distance. Higher power levels and greater distance translate to higher transmission voltages.
Can anyone suggest a rule of thumb?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[slavag]

Hmmm.
Isn't simple Q's.
For example: in my area not used term
sub-transmission. We have distibution system 13kV ( utilities) and facility network ( factory area ) 22kV and 33kV. I think it is also depend on country.
Very problematic Q.
According to Zogzog: LV is <600V and MV up to 69kV, for me it's new, but it's US standard.
I open now some document and see classification:
6-44kV MV distribution
44kV-132kV HV subtransmission
>132kV HV, EHV transmission, and
84-170kV both of them sub/-transmission.
Distance, too problem: I see 170kV lines for 3-5km distance and 20-30 km distance of 22kV.
Maybe parameter is transmission power.
something like to: up to 20-30MVA distribution system
from 30MVA up to ??? subtransmission, etc.
I'm sure: David, Jgrist, Marmite, QBplanner know exactly this ranges.
Best Regards.
Slava

 

[QBplanner]

In the text book you can often see "sub-transmission or UHV,EHV .."
In the company I work (Canada) we simply call what I mentioned above. I am not familiar with system below 12kV. So can not offer any helps.

And it is hard to define the system based on distance or transferred power.

We have a 25kV system supplying loads (5MW) 100km away from sub.

But normally,

25kV is better less than 30km (Distribution, small X/R ratio)
110kV is better less than 100km (Persection).SIL is 50MW
230kV is better less than 200km (Per section). SIL is 140-160MW.
500kV is better less than 300km (per section). SIL is 980-1200MW.

Beyond 300km you may consider DC or compensated AC system with heavy transfer.

Above are just "sound" systems. In reality, we once developed 500km system in 138kv Level. We got full of problems.

THere is a classic paper written by Mr. St. Clair. talking about transfer capability via different transmission system. Becareful of the assumptions he made.
Good luck

 

[honglien]

Thank all of you!
all informations are so useful.
Now, depending on the voltage level, I think the classifications of EPS are:
<= 1kV : Low voltage systems (may be facilities, internal of factories)
1-35kV : Distribution systems (may be utility or facility depending on ranges of use)
35-110kV : transmission systems
110-220kV : subtransmission systems
500kV : EHV transmission systems
But, I was very curious to know the facility networks, as SLAVAG commented, have the voltage levels are up to 22kV, 33kV, much higher than utility systems (12kV). Because in our country, the facilities have the voltage levels are lower than the utilities (up to 35kV).
Could you describe this more clearly?
Thanks alots!

 

[slavag]

Hi Honglien.
Small change:
35-110kV : sub-transmission systems
110-220kV : transmission systems.
According to my post.
In my region we have 3 voltage levels of distribution:
13kV, 22kV and 36kV, for example, in biggest city we have mix of all of them. Some factory have infeed of 170kV and internal transformation to 22kV and distribution in same area is 13kV.
Regards.
Slava