Download Substation Overview

Presentation
by
ABS Ennin, George Coleman, David Dadson &
Anthony Ansah
Introduction
Modern day users of electricity demand a constant and unvarying voltage
and frequency to operate new sophisticated equipment. Customers also
expect electric power 24 hours a day, seven days a week.
Many unpredictable incidents can interrupt the continuous operation of a
power system. Overhead lines may be struck by lightning; untrimmed
trees can fall or blow into a line; strong winds can cause lines to fall or
make contact with each other; ice can accumulate resulting in overstressed
conductors; cars can hit utility poles during an accident; electrical
equipment can fail due to poor maintenance; contractors can dig into an
underground cable; operating personnel can make switching errors. Yet,
customers still expect electric power, on demand. Substations play a
significant role in meeting these requirements.
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OBJECTIVES
Upon completion of this module the participant should be able to:
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Describe the purpose of a substation.
List the types of substations.
State the advantages of various switching configurations.
List the basic components of a substation.
List methods of voltage control in a substation.
Describe the function of metering in a substation.
Describe the function of relaying in a substation
Describe the function of equipment in the control room.
List and describe the function of equipment at the switchyard.
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Purpose of a Substation
Substations play an important role in a power system. Basically, a substation
has three main functions; switching, transform the voltage, and control the
voltage.
An electrical power system is designed so that service will continue despite
any damage or impairment to other components of the system by natural
disaster or other phenomena. When a single element of the system is out of
operation for a period of time, be it a few seconds or several days, the power
system shall be capable of meeting the usual needs of the customer.
Substations represent an important role in providing this reliability.
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Purpose of a Substation
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One important function of substations is switching. Whether it is
switching normal load currents or fault currents, switching protects the
power system and equipment in the event of trouble. Normally, the
switching is done automatically with relaying and circuit breakers or
switches. However, non-automatic switching of circuits can be done if it
becomes necessary to improve reliability or security of the system.
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Purpose of a Substation
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Secondly, substations function to transform the voltage. For economic
reasons, different voltages are used in various parts of the system, ranging
from 11.5kV or lower in distribution systems, up to 330kV in bulk
transmission systems. High voltages are desirable when the amount of
power is great or the distance of transmission is very long. Lower voltages
are advantageous where the amount of power is small or transmission
distances are short. When a substation uses transformers, it represents a
division between sections of the power system with different voltages.
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Purpose of a Substation
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Substations also function to control the system voltage. Various types of
equipment are used to accomplish this. Voltage regulators and load-tap
changers (LTCs) modify the voltage directly; whereas synchronous
condensers, capacitor banks, static voltage compensator (svc) and shunt
reactors control system voltage by modifying the reactive power flow.
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Substation
 Design Stage
 Construction Stage
A substation can be describe into two areas as:
 Switchyard
 Controlroom
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Switchyard
A Switchyard comprises of:
 A Line Gantry
 Incoming Line
 Outgoing Line
 Bus Configuration
 Transformer Bank
 Feeder Structure
 Earthing
 Voltage Control
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Switchyard Equipment
Lines
• Incoming Line Gantry
• Outgoing Line Gantry
• Shield Wire Network
• Line Insulators/Arcing Horns
• Wave Traps
• Line CVTs
• Line Lightning Arrestors/Shaded Rings
• Skywire or Shieldwire
• Line Disconnecting Switches
• By-pass Switches
• Line Breakers – Dead and Live Tanks
• Line Ground Switch
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Switchyard Equipment
- Line Gantry
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Switchyard Equipment
- Line Gantry
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Switchyard Equipment - Line Insulator/Wave Trap/Arcing Horns
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Switchyard Equipment
Arcing Horns
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Switchyard Equipment
Free Standing CTs for SF6 Breaker
“Live Tank”
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Switchyard Equipment
Lightning Arrestor
with Shaded Ring
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Switchyard Equipment
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Lightning Arrestor with Shaded Ring
Surge arresters act to discharge any power surge (transient currents) high
enough to cause serious damage. During normal operating conditions, surge
arresters appear in the system as open circuits. When a disturbance occurs,
such as from a lightning strike or switching surge, surge arresters discharge
transient voltages that can cause serious equipment damage to ground.
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Switchyard Equipment
Free Standing CTs for SF6 Breaker
“Live Tank”
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Switchyard Equipment
Live Tank SF6 Circuit
Breaker
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Switchyard Equipment
Live Tank SF6 Breaker
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Switchyard Equipment
Dead Tank SF6 Breaker
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Switchyard Equipment
Dead Tank
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Switchyard Equipment
SF6 Circuit Breaker
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Switchyard Equipment
SF6 Circuit Breaker
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Switchyard Equipment
Disconnect
Switch
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Switchyard Equipment
Lightning Arrestor
with Shaded Ring
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Switchyard Equipment
CVT with WAVETRAP
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Switchyard Equipment
CVT with Carrier Mounting Device
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Switchyard Equipment
Busbar
 Conductors
 Hollow Bus
 Busbar Insulator Support
 Bus PTs
 Bus CVT/CTs
 Bus Ground Switch
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Substation Bus Configuration
Single Bus
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Substation Bus Configuration
Transfer Bus
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Substation Bus Configuration
Double Bus
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Substation Bus Configuration
Reserve Bus
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Substation Bus Configuration
Ring Bus
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Substation Bus Configuration
Breaker and Halve (Mesh) Bus
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Switchyard Equipment BUS PT
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Switchyard Equipment
Transformer Bank
 Transformer Breakers
 Breaker CTs
 Isolating Switches
 Motorized Disconnect Switch (MOD)
 Transformers
 Free Standing CTs
 Lightning Arrestors /Shaded Rings
 CVTs
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Reactors
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Switchyard Equipment
Feeder Structure
 Feeder Breakers
 Feeder CTs
 Feeder PTs
 Station Service Transformer
 Fused Switches
 Grounding Transformer
 Customer Connections
 Capacitor Banks
 Capacitor Bank Breaker
 Capacitor Bank Ground Switches
 Capacitor Bank Disconnect Switches
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Switchyard Equipment
Current Transformer
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Switchyard Equipment
Voltage Transformer
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Switchyard
Substation Earthing
System Earthing Alternatives
 There are three basic alternatives, isolated systems with no
intentional connection to earth,
 impedance earthed systems with connection through a reactor or
resistor and directly earthed
 systems where transformer neutrals are connected directly to
earth.
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Substation Earthing
Earthing of fences
 Fences around the substation are might be energised through induced
currents from overhead lines passing above. They should always be
connected to encircling earth wires. The best is to put the earth wires
outside the fence, but risks for theft often makes more practical to put
them inside the fence.
 The most common practice is to connect the fence at corners and every
50m along straight stretches. Gateposts shall always be connected. Fences
inside the substation area must also be connected to the earth grid in the
same way. However, for straight stretches, connect at every 10m.
NOTE: if the fence surrounds an air-core reactor group, the fence must be
connected to earth at one place only, and that should be by one gatepost (if
there is a gate). If the fence is connected at more than one place, the magnetic
field surrounding the reactors will drive very
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Switchyard
Voltage Control
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Capacitor Banks
Transformers
SVC Static Voltage Compensators
Reactors
Synchronous Condenser
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Controlroom Equipment
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Annunciator Panel
Relay Panel
Protective Relays
Control Panel
Indicating Lamps
AC 400v Station Service Panel
DC 125V Rectifier
DC 48V Rectifier
125v Battery Banks
48v Battery Bank
DC/DC Converters
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Controlroom Equipment
Annunciator Panel
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Controlroom Equipment
Annunciator Panel
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Controlroom Equipment
Relay Panels
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Controlroom Equipment
Relay Panel
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AC Station Service Panel
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Controlroom Equipment
DC 125V Rectifier
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Controlroom Equipment
DC 125V Panel
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Controlroom Equipment
DC 125V Rectifier
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Controlroom Equipment
DC 48V Rectifier
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Controlroom Equipment
125v DC battery Bank
48v DC battery Bank
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