Substations Bus Arrangements

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substationBackground

A substation is a part of an electricalgeneration, transmission, anddistribution system. Substationstransform voltage from high to low,or the reverse, or perform any ofseveral other important functions.Electric power may flow throughseveral substations betweengenerating plant and consumer, andits voltage may change in severalsteps.
http://en.wikipedia.org/wiki/Electricity_generationhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electricity_generation


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Types of electric substations

There are four major types ofelectric substations

1-The first type is the switchyard at agenerating station.

2-the system substation.

3-the customer substation.4-the distribution station.


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System requirements including

Load growth

System stability

System reliability System capacity


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Customer requirements

including

Additional load

Power quality

Reliability Customer relations

Neighborhood impact


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Site Selection

the following site evaluation criteriacould be used

Economical evaluation

1-return on investment

2-initial capital cost

3-life cycle cost.


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Technical evaluation

1-Land: choose areas that minimize the

need for earth movement and soildisposal.

2-Water: avoid interference with the naturaldrainage network.

3-Vegetation: choose low productivityfarming areas or uncultivated land.

4-Protected areas: avoid any areas or spotslisted as protected areas.

5-Community planning: avoid urban areas,development land, or land held in reservefor future development


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6-Community involvement: engagecommunity in the approval process.

7-Soil: suitable for construction ofroads and foundations; low soilresistivity is desirable.

8-Access: easy access to and from the

site for transportation of largeequipment, operators, andmaintenance teams

9-Pollution: risk of equipment failureand maintenance costs increase withpollution level.


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Design, Construction, and

Commissioning Process

Design

Site Preparation

Drainage, earth work , roads ,access Foundations and concretedesign

StructuresMaterials (electrical , mechanical andchemical effects)


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Buildings

Control, metering, relaying, andannunciation buildings andswitchgear buildings

Mechanical Systems

1- HVAC2- Switchgear building ventilation

3- Fire fighting system


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Electrical Systems

1-Incoming(Transmission line cable )

2-Transformer

2-Ac/Dc room

3-Charger room

4-Battary room

5-General alarm and contol panels6-Protection panels

7-Switch gear and local control panels

8-Interface panels9-Transformer

10-Outgoing(transmission cable)


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Some factors takes into account in electricaldesign

1-insulators(types-rated voltage-switching impulse

level

factors affecting insulators)2-overvoltages(reasons: Atmospheric and switchingovervoltages protective element: surgearresters and skywires)

3- Grounding (Allowable limits of body current-

Allowable limits of step and touch voltages-Soilresistivity-type of earthing method)

4- Neutral Systems(grounded_ungrounded)

Communication system

1-Battery charger2-Battery

3-Communication panels


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Station Construction

With permits in hand and drawings

published, the construction of thestation can begin All the civil,electrical, and electronic systems are

installed at this time. Properattention should also be paid to sitesecurity during the construction

phase not only to safeguard thematerial and equipment, but also toprotect the public.


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Station Commissioning

Once construction is complete, testing of varioussystems can commence and all punch-list items

addressed. To avoid duplication of testing, it isrecommended to develop an inspection, testingand acceptance plan (ITAP). Elements of ITAPinclude

1-Factory acceptance tests (FAT)

2-Site delivery acceptance test (SDAT)3-Site acceptance tests (SAT)

Final tests of the completed substation in apartially energized environment to determine

acceptabilityand conformance to customer requirementsunder conditions as close as possible to normaloperation

conditions will finalize the in-service tests and

turn-over to operations.


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Types of substations according

to its configuration

Outdoor type with air insulatedequipment

Indoor type with air insulated

equipment Outdoor type with gas insulated

equipment

Indoor type with gas insulatedequipment

Mixed technology substations


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Switchgear components

Circuit Breaker

Current Transformers

Voltage Transformers

Disconnect Switches Ground Switches

Surge Arrester

Control System Power Cable Connections

Air Connection


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Bus bar arrangement

1- Single bus


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2- Double busdouble breaker


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3-Main and Transfer Bus

Arrangement


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4-Double bus single breaker


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5-Breaker-and-a-Half

Arrangement


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Thanks

Substations Bus Arrangements

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