Superconducting Magnetic Energy Storage

Presented by-Tanvir Ahmed

Toshon

Outline • Superconductivity• Introduction• History• Components• Operating Principle• Applications & Market

Superconductivity• Superconductivity is a phenomenon of exactly zero electrical

resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.

• Discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 in Leiden, South Holland.

• It is characterized by the  Meissner effect.• Typically two types:

Type I Type II

What is SMES?• 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.

• The conductor for carrying the current operates at cryogenic temperatures 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.

• In this state the current in a coil can flow for infinite time. This can also be seen from the time constant of a coil τ = L/R, where R goes to zero and τ then goes to infinity.

Historical Review of SMES

• 1969: First concept was proposed by Ferrierin in France.

• 1971: Research performed in University of Wisconsin in the US.

• This research led to construction of the first SMES device.

• High temperature superconductors (HTS) appeared commercially in late 90s.

• 1997: first significant size HTS-SMES was developed by American Superconductors. Then it was connected to a scaled grid in Germany.

Components of SMES system

• Superconducting coil with the magnet• The power conditioning system (PCS)• The cryogenic system• The control unit

Superconducting Coil• 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.

• The Size of the coil depends upon the energy storage requirement and coil geometry.• Typically 2 type:

LTS HTS

Power Conditioning System

• Interface between the superconducting magnet and AC power system.• Three configurations available:

Thyristor based PCS. Voltage source converter based PCS. Current source converter based PCS .

Cryogenic Unit• The superconducting SMES coil must be maintained at a temperature sufficiently low to

maintain a superconducting state in the wires.• Commercial SMES today this temperature is about 4.5 K (-269°C, or -452°F) (for LTS)• Reaching and maintaining this temperature is accomplished by a special cryogenic refrigerator

that uses helium as the coolant or liquid nitrogen in case of HTS.• The refrigerator consists of one or more compressors for gaseous helium and a vacuum

enclosure called a “cold-box”, which receives the compressed, ambient-temperature helium gas and produces liquid helium/nitrogen for cooling the coil .

• Since it affect the overall efficiency and cost of SMES system, the loss components such as cold to warm current leads, ac current, conduction and radiation etc. should be minimized to achieve a higher efficient and less costly SMES system.

Control system• Establishes a link between power demands from the grid and

power flow to and from the SMES coil.• 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.

SMES system grid connected configuration

ControllerCoil Protection

CryogenicSystem

VCoil

ICoil

DewarPower Conversion SystemCSI or

VSI + dc-dc chopper

Transformer BypassSwitch Coil

ACLine

Operating Principle• The operation of SMES is based on the fact the a current will continue

to flow in a superconductor even after the voltage across it has been removed.

• A superconducting coil that is cooled below its critical superconducting temperature has negligible (zero) resistance. Thus the current will continue to flow in it.

• The stored energy is inductive: • The coil carries a current at any state of charge• Charging Phase: Since the current flows only in one direction, the PCS

must produce a positive voltage across the coil to store energy. This increases the current.

• Discharging Phase: the PCS are adjusted to make the system look like a load across the coil by producing a negative voltage causing the coil to discharge.

Applications of SMES• System stability: SMES can reduce low

frequency oscillations to enhance transmission capacity and boost voltage stability.

• Power quality: SMES systems can offer energy for flexible AC transmission (FACTS).

Application of SMES• Paper industry• Motor vehicle assembly• Petrochemical Refineries• Chemical & pharmaceutical Companies

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 cycling

efficiency are some additional advantages• It can be deployed in places where other

technologies such as pumped hydro or compressed air are not feasible

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 (3.6 TJ) a SMES installation would need a loop of around 100 miles (160 km).

• Another problem is the infrastructure required for an installation. Until room temperature superconductors are found, the 100 mile (160 km) loop of wire would have to be contained within a vacuum flask of Helium/liquid nitrogen. This in turn would require stable support, most commonly envisioned by burying the installation.

Comparison with other Technologies

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 operation 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.• The cost of storage system is in the range of $85-125K per MJ while the

cost of power conversion system is in the range of $150-$250 per KW.

References• https://en.wikipedia.org/wiki/Superconductivity• http://www.climatetechwiki.org/technology/jiqweb-ee • http://www.library.utoronto.ca/iip/journal/MAIN4/cowles.htm • http://paginas.fe.up.pt/~ee04109/Documentos%20e%20imagens/36%2

0-%20An%20Overview%20of%20SMES%20Applications%20in%20Power.pdf

• http://www.superpower-inc.com/content/superconducting-magnetic-energy-storage-smes

• http://vtb.engr.sc.edu/vtbwebsite/downloads/publications/IEEE%20Sustainable%20energy-published%20paper.pdf

• http://www.slideshare.net/biswajitcet13/superconductivity-15348460?related=1

• https://www.chuden.co.jp/english/corporate/press2007/0615_1.html• http://

www.slideshare.net/GlobalIndustryAnalystsInc/superconducting-magnetic-energy-storage-smes-systems-a-global-strategic-business-report

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