RENEWABLE energy sources will have a key role in supplying energy in the future. There are several issues regarding large scale integration of new renewable into the power system. One of the problems is the security of supply. These energy sources will provide energy, or not provide, independent of the demand. The output power can also have relatively large variations within a short time span. A solution to this problem is the concept of energy storage, and there are several different concepts. There are devices which can store large amounts of energy, but do not react so fast. In the other end there are fast acting devices which store smaller amounts of energy.

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PRESENTED BY:
ROSHNI ABHISIKA
Regd.No :1241019016
EICE ‘A’

2. INTRODUCTION
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RENEWABLE energy sources will have a key role in supplying energy in the future.
There are several issues regarding large scale integration of new renewable into the
power system. One of the problems is the security of supply. These energy sources will
provide energy, or not provide, independent of the demand. The output power can also
have relatively large variations within a short time span. A solution to this problem is the
concept of energy storage, and there are several different concepts. There are devices
which can store large amounts of energy, but do not react so fast. In the other end there
are fast acting devices which store smaller amounts of energy. Superconducting
Magnetic Energy Storage (SMES) is placed in this group.

3. SMES SYSTEM
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• Superconducting Magnetic Energy Storage (SMES) is an energy storage
system that stores energy in the form of dc electricity by passing current
through the superconductor and stores the energy in the form of a dc magnetic
field. [2]
• The conductor for carrying the current operates at cryogenic temperature
where it becomes superconductor and thus has virtually no resistive losses as it
produces the magnetic field.
• The magnetic field is created by flow of direct current through the coil.
• SMES systems are highly efficient; the efficiency is greater than 98%.

4. Components of SMES system
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 Superconducting coil
with the magnet
 The power conditioning
system (PCS)
 The cryogenic system
 The control unit
FIG NO:1
Image courtesy: google
image

5. SMES SYSTEM
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FIG NO:2
Image courtesy: ref [3]

6. Superconducting Coil
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 Main part of a SMES system
 Most superconducting coils are wound using conductors which are comprised of many
fine filaments of a niobium-titanium (NbTi) alloy embedded in a copper matrix. [1]
 The Size of the coil depends
upon the energy storage require-
ment .
FIG NO:3
Image courtesy: google image

7. Power Conditioning System
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The power conditioning system uses an inverter/ rectifier to
transform alternating current (AC) power to direct current or
convert DC back to AC power.
An ac/dc PCS is used for two purposes:
• One is to convert electric energy from dc to ac.
• The other is to charge and discharge the coil.

8. Cryogenic Unit
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The SMES coil must be maintained at a temperature sufficiently low to maintain
a superconducting state. Commercial SMES temperature is about 4.5 K.
It uses helium as the coolant or liquid nitrogen.
The refrigerator consists of one or more compressors called a “cold-box”.
 It affect the overall
efficiency and cost of
SMES system.
FIG NO:4
Image courtesy : ref [2]

9. Control system
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 Establishes a link between power demands from the grid and power flow to
and from the SMES coil. [3]
 Receives dispatch signals from the power grid and status of the coil.
 Maintains system safety and sends system status information to the
operator.
 Modern systems are tied to the internet to provide remote observation and
control.

10. OPERATION OF SMES
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 There are three different modes of operations of the SMES coil :-
• Charging mode
• Stand-by/ freewheeling mode
• Discharging mode
ASSUMPTIONS
 GTO is in ON state means that the duty cycle of that GTO is 1.
 GTO is in OFF state means that the duty cycle of that GTO is 0

11. CHARGING MODE
 GTO2 is always in the ON state.
 In charging mode GTO1 is also in the
ON state.
 When SMES is charging,
Vsmes is the voltage across SMES coil
D is the duty cycle
V dc is the voltage across the dc link capacitor
It takes about 3 sec to charge the coil to its rated current capacity. The current
rises through the SMES coil and the voltage across the SMES is captured.
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Vsmes = D * VDC
FIG NO:5
Image courtesy:ref [1]

12. FREEWHEELING MODE
 This is the second mode of operation.
 Here the current circulates in a closed loop.
 In this mode, any one of the GTO’s is OFF.
 There is no significant amount of loss here,
as the current through the SMES coil is
circulating in a closed loop.
Hence, current remains fairly constant in this mode of operations
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FIG NO:6
Image courtesy: ref[1]

13. DISCHARGING MODE
 The current in the SMES coil discharges into the dc link capacitor in this
mode of operation.
 GTO2 is always OFF.
 Duty cycle of GTO1 can be varied as
per the discharge rates.
 The voltage relationship between
SMES coil and the dc link capacitor
during this mode is:-
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-Vsmes = (1-D) * VDC
FIG NO:7
Image courtesy: ref[1]

14. APPLICATIONS OF SMES
 Paper industry
 Motor vehicle assembly
 Petrochemical Refineries
 Chemical & pharmaceutical Companies
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FIG NO:8
Image courtesy: google image

15. Advantages of SMES
 SMES systems have the ability of fast response.
 They can switch from charge to discharge state (vice versa) within
seconds.
 The absence of moving parts and high efficiency are some additional
advantages.
 It can be deployed in places where other technologies such as battery
system or compressed air are not feasible.
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16. Common Challenges
 Main drawback of the SMES technology is the need of large amount power
to keep the coil at low temperature, combined with the high overall cost for
the employment of such unit.
 To achieve commercially useful levels of storage, around 1 GW.h a SMES
installation would need a loop of around 100 miles (160 km).
 Another problem is the infrastructure required for an installation.
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17. Market Analysis
 It has been estimated that, the total cost to the US businesses of the lost
productivity is a staggering $15-30 billion per year.
 It is estimated that, over 100 MW of SMES units are now operating in
worldwide.
 The global market for SMES is projected to reach US$64 million by 2020.
 At the larger scale, the projected development of a 100 MWh load leveling
system could be implemented during 2020-30.
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FIGNO:9
Imagecourtesy:ref[2]

18. CONCLUSION
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With the advancement in the science of superconductor technology , cost of
installation of the SMES system is eventually going to be comparable to that of
the existing storage technologies.
Hence, it will promote this system which is capable of discharging larger amount
of energy for short period of time thus helping with dynamic performance.

19. REFERENCES
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[1] D.S.Padimiti, B.H. Choudhury, “Super conducting magnetic energy
storage system for improved dynamic system performance,” IEEE Trans.
Power. del. Vol.25, no.3, pp.1816-1827, Jun.2010.
[2] Z. Wang, Z. Zou, Yang Zheng, “Design and control of a photovoltaic
energy and SMES hybrid with current source grid inverter,” IEEE Trans.
Appl. supercond. Vol.2, no.3, pp.254-253, Jun.2013.
[3] R.M. Vamsee, D.S. Bankar, “Control of system under normal grid
condition,” IEEE Trans. Power. electron. Vol.22, no.2, pp.587-594,
mar.2011.
[4] C.A. Luongo, “Superconducting storage systems: An overview,” IEEE
Transaction on magnetics, Vol.32, Issue4, Part 1,pp. 2214-2223, Jul.1996.

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