layout and sld.pptx

7/28/2019 layout and sld.pptx

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Single Line &Layout of

HV Substation

M. M. Meraat

Spring 1392


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Table of content

Busbar arrangement(scheme) selectionBasic Insulation Level

Equipment arrangement


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Busbar arrangement(scheme) selection

Type of busbar arrangement:

Simple/single busbar scheme

Single sectionalized busbar scheme

Single Sectionalized busbar with U configuration

scheme

Main and transfer busbar scheme

Double busbar scheme(with one CB)

Double busbar scheme(with two CB)

Ring bus scheme

Double busbar with bypass disconnector scheme

One and half circuit breaker (conventional)scheme

One and half circuit breaker (Inverted) scheme


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Simple/single busbar scheme Advantage:

One CB for each feeder Simple protection scheme Low space Cost of a single bus arrangement is

relatively low,

Line connections to a single busarrangement are normally straight forward,

since all lines are connected to the same main bus.

Therefore, lines can be connected on themain bus in areas

closest to the direction of the departingline, thus mitigating lines crossing outsidethe substation.

Disadvantage: for a bus outage the entire facility must be

de-energized. There is no alternative way for feeding a

feeder after CB outage Low reliability For any extension , all feeder shall be turn

off

Conclusion: Its suitable for small S/S with less important load


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Single sectionalized busbar scheme Bus section is normally closed

Advantage: If a fault happen in each section

just this section will be disconnect More reliability related to single

busbar For extension its not necessary that

all of the feeder go out

Simple protection scheme Low space

Disadvantage: Any fault at busbar or any problem

for each CB will be lead to fulloutage of its section

There is no alternative way forfeeding a feeder after CB outage For any extension , all feeders of

each section shall be turn off

Conclusion: Its very common in 63 kV substation


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Single Sectionalized busbar with U configuration

scheme

The length of substation will be limited (related toprevious) but its width will be more than previous

scheme

Each feeder (Incoming or outgoing) without relation

to its location can be connected to bus section oneor two


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Main and Transfer Bus System One main busbar In normal operation all feeders will be connected to main busbar

The transfer busbar will be disconnected (off) In maintenance or supervisory of each CB, the related feeder can be fed

through the coupler and disconnector This scheme is appropriate for feeder with less importance which short

outage wont make any disturb The cost of the main and transfer bus arrangement is more than the single

bus arrangement because of the added transfer bus and switchingdevices. In addition, if a low-profile configuration is used, landrequirements are substantially more.

Application of this type of configuration should be limited to low reliabilityrequirement situations.


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Double busbar scheme(with one CB)

Two busbar

Feeders can be connected to busbar one or two With fault in each feeder , this feeder will be disconnected just for a few

moment and will be connected again through the coupler

For a fault in each busbar all of the feeder can be moved to second one.

More reliability but more apace and more cost

It can be implemented back to back either ( for different design)

Relay protection for this arrangement will be complex with the flexibility of

transferring each circuit to either bus. Operating procedures would need to bedetailed to allow for various operating arrangements, with checks to ensure thein-service arrangements are correct. A bus tie breaker failure will cause anoutage of the entire station.


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With two breakers and two buses per circuit, a single bus failure

can be isolated without interrupting any circuits or loads.Furthermore, a circuit failure of one circuit will not interrupt othercircuits or buses. Therefore, reliability of this arrangement isextremely high.

Maintenance of switching devices in this arrangement is very easy,since switching devices can be taken out-of-service as needed

and circuits can continue to operate with partial line relayprotection and some line switching devices in-service, i.e., one ofthe two circuit breakers.

Obviously, with double the amount of switching devices andbuses, cost will be substantially increased relative to other moresimple bus configurations. In addition, relaying is morecomplicated and more land is required, especially for low-profilesubstation configurations.

External line connections to a double breakerdouble bussubstation normally do not cause conflicts with each other, butmay require substantial land area adjacent to the facility as thistype of station expands.


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This arrangement allows for operational flexibility; certain lines

could be fed from one bus section by switching existing devices.


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Ring bus scheme this arrangement affords increased reliability to

the circuits, since with properly operating relayprotection, a fault on one bus section will onlyinterrupt the circuit on that bus section and a

fault on a circuit will not affect any other device. Protective relaying for a ring bus will involve

more complicated design and, potentially, morerelays to protect a single circuit.

Keep in mind that bus and switching devices in aring bus must all have the same ampacity, sincecurrent flow will change depending on theswitching devices operating position.

From a maintenance point of view, the ring busprovides good flexibility. A breaker can bemaintained without transferring or droppingload, since one of the two breakers can remainin-service and provide line protection while theother is being maintained.

The ring bus arrangement is applicable to loads

where reliability and availability of the circuit is ahigh priority.

Disadvantage:a stuck breaker event couldcause an outage of the entire substationdepending on the number of breakers in thering, (b) expansion of the ring bus configurationcan be limited due to the number of circuits thatare physically feasible in this arrangement


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Double busbar with bypass disconnector scheme


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One and half circuit breaker (conventional)scheme In many cases, this is the next development stage of

a ring bus arrangement. Similar to the ring bus, this configuration provides

good reliability; with proper operating relayprotection,

a single circuit failure will not interrupt any othercircuits.

Furthermore, a bus section fault, unlike the ring bus,will not interrupt any circuit loads.

Maintenance as well is facilitated by thisarrangement, since an entire bus and adjacent

breakers can be maintained without transferring ordropping loads.

Relay protection is similar to the ring bus, and due tothe additional devices, is more complex and costlythan most of the previously reviewed arrangements.

The breaker-and-a-half arrangement can beexpanded as needed.

Cost of this configuration is commensurate with the

number of circuits, but based on the good reliability,operating flexibility, and ease of maintenance,

the price can be justified. Obviously, the area required for this type of

arrangement is significant, and the higher the voltage, the more

clearances required and area needed.


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One and half circuit breaker (inverted)scheme


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Basic Insulation Level

The statistical BSL is the crest value of a standardswitching/Lightning impulse for which the insulationexhibits a 90% probability of withstand, a 10%probability of failure.

The conventional BSL is the crest value of astandard switching impulse forwhich the insulationdoes not exhibit disruptive discharge whensubjected to a specific number of applications ofthis impulse.


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Basic Insulation Level For 245kV and Below


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Basic Insulation Level For 300kV and above


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Electrical clearances


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Electrical clearances


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H Scheme


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Double busbar


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Double busbar


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Double busbar


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Double busbar


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Double busbar with bypass DS


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Double busbar with bypass DS


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One and half CB(Conventional)


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One and half CB( Inverted )


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Special design

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