This document discusses the use of vacuum circuit breakers (VCBs) in flexible AC transmission systems (FACTS). It explains that FACTS devices use power electronics to control parameters like voltage, impedance, and phase angle to enhance power grid stability and transfer capacity. VCBs are replacing power semiconductors in some FACTS applications due to lower cost. Specifically, VCBs can be used in mechanically switched series reactors to help damp power oscillations along with thyristor-controlled series compensators. VCBs can also stabilize voltages by connecting capacitors and reactors to load nodes in mechanically switched devices. This allows VCBs to support FACTS technologies in improving power system performance.

1. VACUUM CIRCUIT BREAKERS
IN FLEXIBLE AC TRANSMISSION
SYSTEMS
GUIDED BY, PRESENTED BY,
MRS.ABIDA .C.A VANI.S
ASST. PROF ROLL NO.30
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2. What is a CIRCUIT BREAKER ?
• A circuit breaker is a piece of equipment which can
 Make or break a circuit either manually or by remote
control under normal conditions
 Break a circuit automatically under fault conditions
 Make a circuit either manually or by remote control
under fault conditions
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3. CIRCUIT BREAKER
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4. OPERATING PRINCIPLE
• A circuit breaker consists of a fixed and
moving contacts called , electrodes.
• Under normal operating conditions these
contacts remain closed .
• It will not remain open automatically until and
unless the system becomes faulty .
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5. • When a fault occurs on any part of system ,
the trip coils of the CB get energized .
• The moving contacts are pulled apart by some
mechanism , thus opening the circuit .
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6. CIRCUIT BREAKER TYPES
 Oil Circuit Breakers
 Air Blast Circuit Breakers
 Sulphur Hexafluroide Circuit Breakers
 VACUUM CIRCUIT BREAKERS
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7. LOW VOLTAGE
• Fuse
• MCB
• ELCB
• MCB
• MCCB
• SFU
• ISOLATOR
• CHANGE OVER
• CONTACTOR
MEDIUM ,HIGH VOLTAGE
• ACB
• OLCB
• VCB
• SFC BREAKER
• HT FUSE
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8. FACTS
Alternating current
transmission system
incorporating power
electronics based and
other static controllers to
enhance controllability
and increase power
transfer capability.
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9. • Thyristor or high power transistor is the basic
element of FACTS
• The design of the different schemes and
configurations of FACTS devices is based on
the combination of traditional power system
components (such as transformers, reactors,
switches, and capacitors) with power
electronics elements (such as various types of
transistors and thyristors).
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10. • Thyristor or high power transistor is the basic
element of FACTS
• The design of the different schemes and
configurations of FACTS devices is based on
the combination of traditional power system
components (such as transformers, reactors,
switches, and capacitors) with power
electronics elements (such as various types of
transistors and thyristors).
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11. USES OF FACTS
Devices are used for dynamic control of
voltage,impedance &phase angle of HV ac
lines
Advantages such as
• Ability to damp oscillations
• Improve system stability and enhance power
transfer capability of transmission network.
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12. FACTS IN CIRCUIT BREAKERS
• FACTS are used to increase the transmission
capacity and stability of transmission
networks.
• Stabilize the voltage at load nodes.
• VCB’S are replacing power semiconductors
due to economical reasons.
• VCB’s are most cost efficient.
• available in medium voltage range
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13. APPLICATION OF VCBs IN FACTS
Mechanically Switched Series Reactor (MSSR)
is series connected to a Thyristor- Controlled
Series Compensator(TCSC).
Reactor can be periodically shortcircuited by
VCB’s .
This combination used for power oscillation
damping.
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14. A Mechanically Switched Device (MSD)
consisting of capacitors and a reactor can be
connected to a load node in order to stabilize
the voltage.
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15. REDUCTION IN POWER OSCILLATIONS
• Occurs in electrical power systems
• Such as line faults or substation blackouts
• TCSC used for Power Oscillation Damping
(POD) in TRANSMISSION SYSTEMS
• While damping TCSC runs mainly in Capacitive
Range
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16. OPERATION
• Immediately after a fault , maximum value of
Power Oscillation is reached
• MSSR inserted into the line & Capacitive
Reactance of TCSC has to be minimized
• At minimum PO MSSR has to be removed
• Capacitive reactance of TCSC has to be
increased repeatedly until the PO is damped
sufficiently.
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17. • In steady state operation of the power system
it remains short circuited.
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18. MSSR and TCSC Configuration
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19. Switching status of the VCB
configuration.
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20. VCB IN STABILIZATION OF VOLTAGE
• SVC used to stabilize the voltage at a load
node in power system .
• Improves the Power factor of the connected
load.
• Mechanically Switched Capacitor (MSC) &
Mechanically Switched Reactor(MSR)
connected to HV system by Transformer.
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21. Cont’d
• MSC can avoid voltage instability when load
consists several machines.
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22. CONCLUSION
 The utilization of VCBs in FACTS is promising in
applications- the MSSR & MSD.
 Regarding MSSR
 MSSR can support TCSC to maintain better
performance for Power Oscillation Damping.
 The Time delays of VCBs donot have a negative
influence on POD
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23.  Regarding MSD,
 Can stabilize the voltage at a load node
 It can avoid voltage collapse although VCBs
have time delay
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24. REFERENCE
L. Aengquist, “Synchronous voltage reversal
control of thyristorcontrolled series capacitor,”
• “text book of Electric power generation,
distribution and transmission “by S.N.SINGH
• WIKIPEDIA
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25. ANY QUESTIONS??...
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26. THANK YOU
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27. BREAKER PARTS
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