SURGE PROTECTION USING SUPERCONDUCTORS

ByJ DAVID MANOHAR

(08A31A0232)

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

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

In past we are limiting fault current by artificially raising the impedance

Now such methods are inconsistence for today’s demand of high power quality

These drawbacks can be overcome by using fault current limiter

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

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

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

FAULT CURRENT LIMITER

Recently the distributed generators are introduced to the load system side

The fault current will increase with installation of DG’s

Usually a limiting reactor is set in series with DG’s

If you use SCFCL in place of reactor it reduces fault current and transmit maximum power under steady state condition

ADVANTAGES OF SCFCL OVER REACTOR

It can be decided by conducting two tests

I. 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

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

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

SCFCL BENEFITS

Safety, reliability and power quality

Cost for circuit breaker and fuses can be reduced

Reduce voltage drops

Enhance grid stability

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

THANK YOU