SURGE%20PROTECTION%20USING%20SUPERCONDUCTORS

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SURGE PROTECTION USING SUPERCONDUCTORS

• By
• J DAVID MANOHAR
• (08A31A0232)

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NECESSITY OF SUPERCONDUSTOR

• Damage from short circuit is constant threat in
  power systems
• All the power systems components must be designed
  to withstand over short circuit stresses
• If the higher fault currents are anticipated then
  higher equipment required . Hence maintenance
  cost increases

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PROPERTIES OF FAULT CURRENT LIMITER

• Having zero impedance under normal operation
• It provide larger impedance whenever any fault
  occur
• It provides immediate recovery after clearing the
  fault
• It has a capacity to addressing two faults within
  a period of 15 sec

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• In past we are limiting fault current by
  artificially raising the impedance
• Now such methods are inconsistence for todays
  demand of high power quality
• These drawbacks can be overcome by using fault
  current limiter

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SUPERCONDUCTORS

• Because of their sharp transition from zero
  resistance at normal operations to higher
  resistance in the fault condition
• Super conductors having critical temperature can
  be maintained by liquid nitrogen

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TYPES OF SCFCL

• RESISTIVE SCFCL
• In RESISTIVE SCFCL the super conductor is
  directly connected to line to be protected
• It was immersed in a coolant and it chilled by
  refrigerator
• Current leads are design to transfer heat from
  outside to coolant

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• SHIELDED CORE SCFCL
• The shielded core fault current limiter basically
  a shorted transformer
• Here the superconductor is connected to the line
  not directly but magnetically
• The primary coil is connected in series to the
  line to be protected and secondary side is
  superconducting and shorted

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FAULT CURRENT LIMITER

• Recently the distributed generators are
  introduced to the load system side
• The fault current will increase with installation
  of DGs
• Usually a limiting reactor is set in series with
  DGs
• If you use SCFCL in place of reactor it reduces
  fault current and transmit maximum power under
  steady state condition

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ADVANTAGES OF SCFCL OVER REACTOR

• It can be decided by conducting two tests
• Current limiting test
• Consider generator output and load are 3KW and
  1.5 KW respectively
• If the peak of the fault current is 120 amps
  without SCFCL , it is suppressed to 46.3 amps
• Without SCFCL the power to the load during the
  fault dropped almost zero KW on other hand it was
  kept to some level with SCFCL

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• STEADY STATE STABILITY TEST
• Consider a reactor whose impedance is same as
  SCFCL in current limiting mode
• The steady state stability test carry out through
  SCFCL or reactor
• The SCFCL reduce fault current without decreasing
  maximum power and stability margin

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RESULTS

• The SCFCL turns in to current limiting mode when
  fault current reached to triggering current
• The DG is successfully from over current at the
  fault condition
• Power supply to the load continuous to certain
  extent during the fault
• SCFCL reduce fault current without decreasing
  maximum power and stability margin

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SCFCL BENEFITS

• Safety, reliability and power quality
• Cost for circuit breaker and fuses can be reduced
• Reduce voltage drops
• Enhance grid stability

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CONCLUSION

• The purpose of this paper was the study of surge
  current protection using superconductors the
  SCFCL offers efficient advantages to power system
  and opens of major applications for
  superconducting material

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THANK YOU