Substation

Source: Lakervi & H Holmes

The substation

Olof Samuelsson

Outline

• The substation • Substation equipment • Overhead lines

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

Substation

2

From generator to customer

Generation | Transmission | Distribution | Consumption

Source: vattenfall.se

Östra mottagningsstationen, Lund At the city limit

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

Substation

3

Substation functions • Voltage transformation (reduction) – Power transformer • Connection point for local networks • Switchyard for network configuration – Bus bars, bars circuit breakers, breakers disconnectors • Monitoring point for control center – Potential and current transformers • Fuses and other protection

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

Substation

4

Substation equipment symbols ENGLISH Busbar Generator Two-wdg Two wdg transformer Line Circuit breaker Disconnector Surge arrester Current transformer Potential transformer

SVENSKA Samlingsskena g Transformator Ledning Effektbrytare Frånskiljare Ventilavledare Strömtransformator Spänningstransformator

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

Substation

5

Layout

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

Substation

6

Circuit breaker S d USA Sweden

Sourcee:ABB

Open Closed

• Interrupts large current – Several kA – Short-circuit current – Hidden contacts • Control – Protection systems – Manual remote • Design challenge – Speed and current

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

Substation

7

Disconnector / Isolator • Interrupts small current – Load current • Visible interruption • Manual control or motorized • Design challenge: Weather

Sweden USA Open Closed

Open p

Closed

Source: Nicklasson Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

Substation

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

Lindome 400 kV station Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

Substation

9

Current transformer

B Source:ABB

• Reduces current – Typically 1000/2 A • Current monitored – Control center – Protection equipment – P, Q transducers

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

Substation

10

Sou urce:ABB

Voltage/potential transformer

• Reduces voltage – Typically x kV/110 V • Voltage monitored – Control center – Protection equipment – P, Q transducers Al C voltage lt di id • Also divider

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

Substation

11

Surge / lightning arrester

• O Overvoltage lt trap t • Alternative to air gap • Nonlinear resistance • Short-circuits high voltages o tages to ground g ou d

Source: ABB Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

Substation

12

GIS - Gas Isolated Switchgear SF6

Air

Source: Lakervi

• SF6 gas g – Isolates much better than air - reduces size – Greenhouse gas Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

Substation

13

Source: Nicklasson

Transmission towers

400 kV

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

750 kV

Substation

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Insulator disks

Voltage level Source:Glover & Sarma

Flashover distance

Number of disks

Air humidity y Lund University / LTH / MIE / Industrial Electrical Engineering and Automation

Substation

15

Effects of short-circuit current • Vibration due to magnetic forces – Parallel conductors are attracted (F=B·i·l) • Arc – Compare with welding g from current and arc • Heating – Fire and explosion • See http://205.243.100.155/frames/longarc.htm

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

Substation

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