220 kV AIS Switchyard

7/29/2019 220 kV AIS Switchyard

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Project By

Mohammed Mahmooduddin

Syed Abbas Noori

Syed Obaidur Rahman

Under guidance of

Mrs. Ajaz Fatima(internal)

Mr. M.A. Ahmed(external)


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PROJECT

To design the switchyard is to evacuate the power from 375 MWCombined Cycle Power Plant.

Purpose:

The substations are very much essential to Evacuate power from generating stations.

Transmit to the load centers.

Distribute to the utilities & ultimate consumers


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WHY SUBSTATIONS ? The Electrical power generation from Hydel, Thermal,

Nuclear and other generating stations has to beevacuated to load centers.

The generation voltage is limited to 15/18 KV due to thelimitation of the rotating machinery.

This bulk power has to be stepped up to higher voltages

depending on quantum of power generated anddistance to the load centers.

Again the power has to be stepped down to differentlower voltages for transmission and distribution


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TYPES OF SUBSTATIONS

The substations are classified as

a)Generating substations (Switchyard)

b) Grid substations

c) Switching stations

d) Secondary substations.


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Generating substations (Switchyard)

The generating substations are step up stations as thegeneration voltage needs to be stepped up to theprimary transmission voltage so that huge blocks ofpower can be transmitted over long distances to loadcenters


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grid substations The grid substations are created at suitable load

centers along the primary transmission lines


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Switching stationsSwitching stations are provided in between lengthy primarytransmission lines

To avoid switching surges.

For easy segregation of faulty zones. For providing effective protection to the system in the A.C.network.

The switching stations also required wherever the EHT lineare to be tapped and line to be extended to different load

centers without any step down facility at the switchingstations. The number of outgoing lines will be more than the

incoming lines, depending on the load points


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Secondary substations Secondary substations are located at actual load points

along the secondary transmission lines where thevoltage is further stepped down to sub transmission &primary distribution voltage.

Distribution substations are created where the sub-transmission voltage and primary distribution voltage

are stepped down to supplyvoltage and feed the actual consumers through a

network of distribution and service lines.


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TRANSMISSION SUBSTATION

DISTRIBUTION SUBSTATION

COLLECTOR SUBSTATION

CONVERSION SUBSATION

SWITCHING SUBSTATION

ADJUST THE ABOVE HERE


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SELECTIONOFSITE

Selection of site for construction of a Grid

Sub Station is the first and important activity.

This needs meticulous planning, fore-sight,skillful observation and handling so that the

selected site is technically, environmentally,

economically and socially optimal and is thebest suited to the requirements.


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SOCIALANDCOMMUNITY ENVIRONMENTAL

What are the predicted futureenergy requirements of the

community?

What is the land zoning of the

site and its proximity to

residents? What is the likely visual impact,

considering the direct line of

sight, substation height and

visual screening options?

Can the substation be locatedas to not disturb surrounding

residents and if not, can a

design solution be determined?

Are there any potential impactson declared rare flora or fauna,

priority flora or threatened

ecological communities?

Is the site likely to impact anunderground water protection

area or wetland system?

Is a design option likely to

impact on any knownIndigenous or European

heritage sites?


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TECHNICALREQUIREMENTS

Is the location close to the load area that it will service?

Is the substation located as close as possible to existingtransmission lines, from which it will draw its power?

Does the site allow for connection of in-coming transmission lines

and out-going underground distribution lines?

Is the site far enough away from underground copper cables (eg.telecommunications cables) and the steel pipelines used by gas and

water companies, so that earthing and voltage induction issues can

be avoided. Where this cannot be avoided, costs to mitigate are

extreme.

Could a standard design be accommodated on the site, or are therespecial design considerations?

Physical constraints such as slope, geology, water table and

flooding.

Engineering features such as vehicle access, earthworks and

services.


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ECONOMICREQUIREMENTS

As a regulated body, can we satisfy the

Economic Regulation Authority that the most

cost effective solution has been identified? What alternative solutions are available?

Can cost effective improvements to the design

reduce the visual impacts on the community?


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REQUIREMENT OF LAND/AREA

The site should have sufficient area to properly accommodate the Sub

Station buildings ,structures ,equipments, etc. and should have the

sufficient area for future extension of the buildings and / or switchyard.

The requirement of land for construction of Sub SUBSTATION1. 400 kV 20.0 Hectare

2. 220 kV 6.0 Hectare

3. 132 kV 3.5 Hectare

While preparing proposals for acquisition of private land and allotment

of Government.


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SYSTEMBUSES

The main criterias to be considered during selection of

one particular Bus Bar Arrangement Scheme among

others

i. Simplicity of system

(ii) Easy maintenance of different equipments.

(iii) Minimizing the outage during maintenance.(iv) Future provision of extension with growth of demand

(v) Optimizing the selection of bus bar arrangement

scheme so that it gives maximum return from the system.


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Types of system


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DOUBLE BUS SYSTEMWITH BYPASS

ISOLATORS This is combination of the double bus

system and main and transfer bussystem.

In Double Bus System with Bypass

Isolators either bus can act as main bus

and second bus as transfer bus.

It permits breaker maintenance withoutinterruption of power which is not

possible in double bus system but it

provides all the advantages of double

bus system.

It however requires one additionalisolator (bypass isolator) for each feeder

circuit and introduces slight complication

in system layout. Still this scheme is best

for optimum economy of system and it is

best optimum choice for 220KV system.


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EQUIPMENTSCOMMONLYFOUNDIN

SWITCHYARD Lightening arrestor

Current transformer

Voltage transformer Power transformers / I.C.T.

Bus bar and clamp fittings

Support structure Isolators

Circuit Breaker

Wave traps


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EQUIPMENTSINASUB-STATION

Transformers :

- Transforms the voltage levels from higher to lower level

or vice versa, keeping the power constant.

Instrument transformers :

- For stepping-down the electrical parameter (Voltage or Current) to

a lower and safe value for Metering and Protection logics.


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Earth switch :

- Used to connect the charged body to ground to discharge thetrapped charge to have a safe maintenance zone

Lightning arrestors :- Safe guards the equipment by discharging the high currents

due to Lightning.


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EQUIPEMENTSOverhead earth wire :

- Protects the O/H transmission line from Lightning strokes.

Wave Traps/Line traps :

- Used in PLCC circuits for Communication and Protection of

Transmission lines


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Reactive Power control devices :

- Controls the reactive power imbalance in the grid byswitching ON/OFF the Shunt Reactors, Shunt Capacitors etc.,

Current Limiting Reactors :

- Limits the Short circuit currents in case of faulty conditions


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EQUIPMENTINBUSCOUPLERBAY

Circuit breakers Makes or automatically breaks

the electrical circuits underLoaded condition

Interrupting short-circuit current

Reliable protection of motors

Protection of leads and itsoptimum utilisation

Protection of installations

Integration in the control circuit Switching under normal service

conditions

Disconnecting function


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Operates under off-load

conditions

Physically isolates the electric

circuit

Does not have any current

making & breaking capacity

Used in addition to C.B.

isolators

220 kV AIS Switchyard

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