Insight regarding Typical High Voltage Power Systems 1

[Wfg42438]

Hello,

I am recent graduate who has had some minor exposure to Power Engineering courses. I have been doing some research regarding Short circuit and Arc Flash studies performed for Power engineering systems. Using Jim Phillips "Guide for: Arc-Flash Hazard Calculations" i have learned some basics for SC/AF calculations and now wish to extend my knowledge using the ETAP software. I have been running some Short Circuit/AF studies using sample systems provided by the software however i know wish to build my own system. I was hoping i can have some feedback here in the forum from users who have field experience. I want to run some SC/AF studies for High Voltage Power systems however i don't know what the typical equipment & ratings one would expect in HV systems.

I want to this as a learning exercise so i can see what kind of HV systems are out in the field and realistic SC/AF results

Any help would be greatly appreciated, also if anyone could recommend good books to read that would much appreciated

 

[Mbrooke]

Here in the US typical substation breaker ratings are 10ka for 12.47kv distribution, 40ka for 115kv systems and 63ka for 345kv systems. 63ka is generally the highest rating, though there are some POCOs that use (and need) 80ka breakers at the 115kv and higher levels. These are selections made on the worst case fault current (or worst case X/R ratio), however in any typical system fault current will vary tremendously based on generation dispatch, conductor size, and where you are in the power system.


The following are very, very, very rough (average) values but generally one gets about 10,000amps in front of a 40MVA transformer feeding a 12kv distribution system, with fault current falling sharply as you go down the 12kv line to about 2000 amps and lower. Typical fault currents on the 115kv side of a bulk distribution station are 15,000 to 20,000amps; with 40,000 at a 115kv generating station. Typically one gets about 60,000+ on the 115kv bus of a bulk transmission substation (345kv stepped down to 115kv via 2 or 3 600MVA autotransfomers). Typical fault currents at the 345kv level are 50,000amps. I've heard of worst case scenarios with 220kv generating stations exceeding 78,000amps short circuit. But as I've said these are typical numbers, in reality they will vary.

ETAP software (or anything like Power World) is the right way to go. This is not meant to undermine mathematical geniuses, but typically in a major power system the variables become so great and so dynamic relative to one another that it is the only easy way to obtain good, solid short circuit values.


As for arc flash, it is generally not to much of a concern in open air outdoor bus work if you are standing at ground level, even at levels which would normally be dangerous in an enclosed area.


I am not good with books, but I know someone will recommend something good regarding those two.

 

[Wfg42438]

Mbrooke,

Thank you so much for the information you listed its helping put things in perspective.

Do you know if there's anyway I would be able to find a one line diagram of a typical substation?

So I could see the typical layout and equipment involved in a HV substation

This would really help build a realistic HV system to start simulating with ETAP

 

[jghrist]

Are you looking for industrial systems or utility systems? For industrial system, IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (Red Book) Std 141 is a good place to start. It has worked out calculation examples. Note - the IEEE color book series is being replaced by the P3001.x Power Systems Design series of standards, drawing from elements of the existing Gray, Red and White Books.

 

[Mbrooke]

Welcome

Typical substation- which kind? There are many different kinds out in the real world. However in a nut shell the majority of substations on earth boil down to these 9 basic layouts per voltage level:


1. Straight bus

2. Straight bus with one (or more) bus sensationalizing breakers

3. Main and transfer bus

4. Single breaker, double bus

5. Single breaker, double main bus with transfer bus

6. Ring Bus

7. Breaker and a Half

8. Double breaker double bus

9. Breaker and a quarter. This one is technically rare, but I see it popping up in new GIS designs.

You may find a few odd balls outside of these 9 like single breaker triple bus and folded (crossed/meshed) rings bus, but these are generally rare enough that they can be ignored when studying the basics.


Regarding Single line diagrams for beginners I highly recommend studying these:

http://www.bsptcl.in/SingleLineDiagram.aspx

Here is a nice one (220/132/33kv):

http://www.bsptcl.in/FINAL_SLD/SIPARA.pdf

A simpler one (132/33kv):

http://www.bsptcl.in/FINAL_SLD/SAMASTIPUR.pdf

This is only how one company does it. The majority are main and transfer bus, 132kv stepped down to 33kv. Some are of better quality than others, but none the less they give good interpretation, depiction and labeling of the individual parts.


This PDF has pictures of substation and comparison of the different parts:

http://sites.ieee.org/houston/files/2016/04/2012-10-02-HV-Substation-Application-Design-Oct-2-3.pdf

This might also be helpful starting on page 84 (actual number on the page)

http://www.energy.siemens.com/hq/po...e/71/05-Switchgear-and-Substations.pdf#page=8

This condenses an HV network down to a nut shell:

https://www.slideshare.net/atulpathak/insulation-16539878

Let me know if these help.

 

[Mbrooke]

Came across this vid where you can see things up close:

https://www.youtube.com/watch?v=ZnlUKAxqz5Y