Power System Analysis

[gokulkrish2]

Hello everyone,

I need your help on a project assigned to me. I am doing an internship in a Mining company. They have asked me to look into the one line diagram of the power system of the mine and give suggestions on where they have to place extra or additional circuit breakers and tie breakers so that they can make sure that they have minimum plant operation in case of faulted conditions and maintenance.

Now I am a Electrical Engineer with Power engineering as specialization. I know the basic stuff and hope can understand whatever you guys explain. I dont know on where to start with this project. Im kind of thinking wat to do. so thought you guys will be helpful

First of all i need to know wat all inputs i need.

I have got the one line diagram alone. (Also all the rating of all the equipments in the system)
what else do i need.

please suggest me something.

Any literature on this topic?

I would be very glad to learn on this topic.

awaiting your replies.

gokul

 

[ykee]

I'm not sure about literature that is available, but if you have the single line, that is a good start. Next, you need to find out how important it is that various pieces of equipment stay running, and what happens if there are brief power interruptions. You'll need to look at what sort of back-up power you have, and how this matches the loads that you want to run. You also need to consider failure modes: as in if breaker X trips, what does it bring down.

I think for you, the bottom line is that you need a thorough understanding of what equipment is used for, and what can and what can't be without power for a long time. Once you've figured this out, then you can figure out where to place tie breakers, what sort of transfer switches, if back-up power is sufficient etc.

You should also make sure that you've got a reasonable protection & coordination study of the existing installation.

 

[cflatters]

T do the job properly, you have to consider a whole number of issues - in fancy words FMEA (Failure Mode Effects Analysis) - but put more simply;

Look at the reslience of your network ?

Look at each load, presumably you have certain critical loads (eg fire pump, water drainage pumps, ventilation fans).
- What are / where are your critical loads ?
- What could cause the suuply to these to fail and what would the consequences be of a failure ?
- How much time do you have if one of your critical loads fails ?

If you have a critical load eg how can you mitigate against failure - can you feed duty and standby pumps from separate sources, or do you have different means of addressing issues (eg in NFPA20, it is common to have 1 diesel and 1 electric fire pump otherwise electric pumps must have duplicate supplies from separate sources).

Also what standby capacity do you have ?
Do you need to shed load if your main source fails (if so how much) ?

How effective is your protection system, is it properly graded & has it been regularly injection tested ?
Has your switchgear been maintained regularly ?

These are all questions that you need to evaluate (you may need to ask others for input.

Hope this helps a little

 

[lansford]

Get hold of the IEEE colored book series such as the Red and Buff Books and start there.
JIM

 

[cuky2000]

Consider the help ofr a consulting engineering firm specialized in this area.
Some of the related topics mah he: double breaker, breaker 11/2, redundant power sources, reliability, protection coordination, etc

 

[slavag]

Im with Cuky2000, but other gave you very good tips, what information you have prepare for consalting

 

[JustSumGuy]

It sounds like you have two scenarios; 1) A Fault Condtiton and 2) Maintenance.

The Fault Condition requires a coordination study to see under which conditions and in what order your breakers will trip. A coordination study is easier if you have software tools such as EasyPower or ETAP. Basically you will have to study the combined Time-Current Curves of the breakers involved.

The Maintenance Condition requires a review of the plant's distribution system to see where you might be able to employ tie-breakers, redundant feeders, generation, and ATS systems.

I'm not sure of your experience level, but these are not typically the kinds of studies a novice engineer should take on.

Good Luck.

 

[PUNGLU]

With your single line diagram you will of course have sensing/relaying points. You must have the:
i) muximum fault currents for faults at these points
ii)minimum fault currents for faults at these points
iii) muximum through fault currents at these points
These basics plus all that you alredy have from the above threads should help. The software tols will come in handy since the analysis may get messy...