the substation - · pdf filelund university/ lth / mie / industrial electrical engineering and...

The substation

Hol

mes

: Lak

ervi

& H

Sour

ce

Olof Samuelsson

Outline

• The substationThe substation• Substation equipment• Overhead lines

Lund University / LTH / MIE / Industrial Electrical Engineering and Automation 2Substation

From generator to customer

Generation|

TransmissionTransmission|

Distribution||

Consumption

Source: vattenfall.seÖstra mottagningsstationen, Lund

At the city limit

Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

At the city limit

3Substation

Substation functions

• Voltage transformation (reduction)– Power transformer

• Connection point for local networks• Switchyard for network configuration

Bus bars circuit breakers disconnectors– Bus bars, circuit breakers, disconnectors• Monitoring point for control center

– Potential and current transformers• Fuses and other protection


Substation equipment symbols

ENGLISHBusbar

SVENSKASamlingsskenaBusbar

GeneratorTwo-wdg transformer

g

TransformatorTwo wdg transformerLine

Circuit breakerLedningEffektbrytareCircuit breaker

DisconnectorSurge arrester

EffektbrytareFrånskiljareVentilavledareSurge arrester

Current transformerPotential transformer

VentilavledareStrömtransformatorSpänningstransformator


Potential transformer Spänningstransformator

5Substation

Layout


Circuit breakerS d USASweden USA

Open Closed• Interrupts large current

– Several kA

Open Closed

– Short-circuit current– Hidden contacts

• Control– Protection systems

e:A

BB

– Manual remote• Design challenge

Sour

ce


– Speed and current

7Substation

Disconnector / Isolator

• Interrupts small current– Load current

Sweden USA

• Visible interruption• Manual control or motorized

Open Closed

• Design challenge: Weather

Open Closedp


Source: Nicklasson

8Substation

Disconnecting circuit breaker• Combines breaker and disconnector• Combines breaker and disconnector• More reliable and compact


Lindome 400 kV station

Current transformer

• Reduces current– Typically 1000/2 ATypically 1000/2 A

• Current monitored– Control centerControl center– Protection equipment– P, Q transducers

BSo

urce

:AB

B


Voltage/potential transformer

• Reduces voltage– Typically x kV/110 V

urce

:AB

B

• Voltage monitored– Control center

Sou

– Protection equipment– P, Q transducers

Al C lt di id


• Also C voltage divider

11Substation

Surge / lightning arrester

O lt t• Overvoltage trap• Alternative to air gap• Nonlinear resistance• Nonlinear resistance

• Short-circuits high voltages to groundo tages to g ou d


Source: ABB

12Substation

GIS - Gas Isolated Switchgear

AirSF6

Source: Lakervi

• SF6 gasg– Isolates much better than air - reduces size– Greenhouse gas


Transmission towers

: Nic

klas

son

400 kV 750 kV

Sour

ce

400 kV 750 kV


Insulator disks

Voltage level

Flashover distance Number of disks

Source:Glover & Sarma

Air humidity


y

15Substation

Effects of short-circuit current• Vibration due to magnetic forcesVibration due to magnetic forces

– Parallel conductors are attracted (F=B·i·l)• ArcArc

– Compare with welding• Heating from current and arcg

– Fire and explosion• See http://205.243.100.155/frames/longarc.htm


the substation - · pdf filelund university/ lth / mie / industrial electrical engineering and...

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