MICROGRID CONCEPTS
AND ENERGY STORAGE
SYSTEMS
ABIN BABY,
13112602,
S7 EEE.
COLLEGE OF ENGINEERING MUNNAR

OUTLINE
• Introduction to Microgrid.
• The Need of Microgrids.
• Components of Microgrids.
• Microgrid Operating Modes.
• Need for ESSs in Microgrids.
• Energy storage technologies.
• Advantages & Disadvantages of Microgrid.
• On going Microgrid activities.
• Future Directions on Microgrid Research.
• References.
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INTRODUCTION TO MICROGRID
•What is Microgrid?
•A group of interconnected loads and
distributed energy resources within clearly
defined electrical boundaries that acts as a
single controllable entity with respect to the
grid.
•Enables local power generation for local loads.
•Comprises of various small power generating
sources that makes it highly flexible and
efficient.3 COLLEGE OF ENGINEERING MUNNAR

INTRODUCTION TO MICROGRID
•What is Microgrid?
•It is connected to both the local generating
units and the utility grid thus preventing
power outages.
•Excess power can be sold to the utility grid.
•Size of the Microgrid may range from
housing estate to municipal regions.
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KEY ATTRIBUTES OF MICROGRID
•Grouping of interconnected loads and
distributed energy resources
•Can operate in island mode or grid-connected
if desired
•Acts as a single controllable entity to the grid
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THE NEED OF MICROGRID
• Microgrid could be the answer to our energy crisis.
• Transmission losses gets highly reduced.
• Microgrid results in substantial savings and cuts
emissions without major changes to lifestyles.
• Provide high quality and reliable energy supply to
critical loads
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COMPONENTS OF MICROGRID
•Distributed Generation
•Loads
•Energy storage systems
•Static disconnect switch
•Controller
•Mode switching device
•Point of Common Coupling
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Hybrid AC/DC
Microgrids
Main
Utility Grid
PCC
Household appliances and electronics
DC Coupled Subsystem
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THE NEED OF MICROGRID
• Microgrid could be the answer to our energy crisis.
• Transmission losses gets highly reduced.
• Microgrid results in substantial savings and cuts
emissions without major changes to lifestyles.
• Provide high quality and reliable energy supply to
critical loads
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MICROGRID OPERATING MODES
• Grid Connected Mode:
• Utility grid is active.
• Static switch is closed
• All the feeders are being
supplied by utility grid.
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Main
Utility Grid
PCC
Household appliances and
electronics
DC Coupled
Subsystem
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MICROGRID OPERATING MODES
• Island Mode:
• Utility grid is not supplying power
• Static switch is open.
• Feeder A, B, C are being supplied
by Microsources.
• Feeder D (not sensitive )
is dead.
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Household appliances and
electronics
DC Coupled
Subsystem
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NEEDS OF ESS IN MICROGRIDS
• Crucial element in the integration of DG into
Microgrid.
• Critical role in stabilising the voltage and
frequency.
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ENERGY STORAGE IN MICROGRID
High Performance:
• Avoid costly downtime and battery replacements
• Very high cycle life
• Extremely abuse tolerant
• Ability to stand at partial state of charge
• High efficiency
• Self-balancing
• Wide operating temperature range
• Minimal degradation
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 Safe:
• Inherently safe chemistry
• Not flammable, explosive, or corrosive
• No dangerous or toxic components
 Sustainable:
• Simple, abundant, nontoxic materials
• Environmentally benign materials
• No corrosive acids or noxious fumes
• Suitable for deployment globally
Excellent Economics:
• Industry-leading total cost of ownership
• Low acquisition costs ($/kWh)
• Better value than lead acid or lithium ion
• No regular maintenance
• No thermal management
• No active management required
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ENERGY STORAGE SYSTEM
 ESS include electrochemical battery, super capacitor,
compressed air energy storage, super conducting energy
storage, flywheel energy storage etc. .
 Lithium ion is commonly used because best energy to weight
ratio and slow loss of charge when not in use.
 ESS store energy at the time of surplus and redispatch it
when needed.
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 ESS plays an important role in microgrid.
 Sizing of ESS to be considered first when considering ESS in
Microgrid.
 ESS increase the reliability of power system.
 The cost of ESS includes one time ESS cost and the annual
maintenance cost.
 The battery storage system made up of small battery blocks.
ENERGY STORAGE SYSTEM
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ESS IN ISLANDED MICROGRID
 Sizing of a suitable battery bank in terms of power and
energy help in shaving the peak demand.
 Stores excess renewable energy and supply load when
renewable energy is low.
 When ESS discharges its energy to power grid, its generating
positive real power
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ESS IN GRID CONNECTED MICROGRID
 The upstream grid can be treated as bidirectional generator
which generate positive power when power is transferred
from the MG and generate negative power when the power
transferred from the Microgrid to upstream grid.
 The output of bidirectional generator is limited by the
capacity of transmission line between the Microgrid and
upstream grid.
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ENERGY STORAGE TECHNOLOGIES
• Ultracapacitors.
• Superconducting magnetic ESS.
• Compressed air.
• Pumped hydro.
• Fuel cells.
• Fly wheels.
• Batteries.
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TYPES OF BATTERIES
•Nickel Cadmium.
•Lead Acid.
•Li-ion.
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ON GOING MICROGRID ACTIVITIES
•CERTS
*Demonstrated in Santa Rita jail, in California
*Main objective-
Reduce Microgrid system cost
Increase reliability
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•Fort Sill
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•SPIDERS program
•Illinois Institute of Technologies perfect power system
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CONVENTIONAL GRID VS. MICROGRID
•Efficiency of conventional grid is very low as compared
to Microgrid.
•Large amount of energy in the form of heat is wasted
in conventional grid.
•Power sources in case of Microgrid (often referred to
as Microsources) are small and are located in close
proximity to load.
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ADVANTAGES & DISADVANTAGES
• Microgrid Advantages
• A major advantage of a Microgrid, is its ability,
during a utility grid disturbance, to separate and
isolate itself from the utility seamlessly with little
or no disruption to the loads within the Microgrid.
• In peak load periods it prevents utility grid failure
by reducing the load on the grid.
• Significant environmental benefits made possible
by the use of low or zero emission generators.
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ADVANTAGES & DISADVANTAGES
• Microgrid Advantages
• The use of both electricity and heat permitted by
the close proximity of the generator to the user,
thereby increasing the overall energy efficiency.
• Microgrid can act to mitigate the electricity costs
to its users by generating some or all of its
electricity needs.
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ADVANTAGES & DISADVANTAGES
• Microgrid Disadvantages
• Voltage, frequency and power quality are three
main parameters that must be considered and
controlled to acceptable standards whilst the
power and energy balance is maintained.
• Electrical energy needs to be stored in battery
banks thus requiring more space and
maintenance.
• Resynchronization with the utility grid is difficult.
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ADVANTAGES & DISADVANTAGES
• Microgrid Disadvantages
• Microgrid protection is one of the most important
challenges facing the implementation of
Microgrids.
• Issues such as standby charges and net metering
may pose obstacles for Microgrid.
• Interconnection standards needs to be developed
to ensure consistency. IEEE P1547, a standard
proposed by Institute of Electrical and Electronics
Engineers may end up filling the void.33 COLLEGE OF ENGINEERING MUNNAR

FUTURE DIRECTIONS ON MICROGRID
RESEARCH
• To investigate full-scale development, field demonstration,
experimental performance evaluation of frequency and voltage control
methods under various operation modes.
• Transition between grid connected and islanded modes on interaction
phenomena between distribution generation and high penetration of
distributed generation.
• Transformation of Microgrid system today into the intelligent, robust
energy delivery system in the future by providing significant reliability
and security benefits.
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FUTURE SCOPE
• In the near future when cost of Microgrid system will be
affordable then Microgrids will become more popular and
conventional grid will be replaced by Micro grid.
• Research are going such as to increase stability and reliability
of the Microgrid for effecttive working.
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CONCLUSION
• Micro-Grid gives impetus to the
use of Renewable sources of
energy.
• Reliability is achieved due to
decentralization of supply.
• In an event of Power Grid
failure Micro-Grid is one of the
best alternatives.
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REFERENCES
• [1] H. Rongxian , L. Zhiwen , C. Yaoming , W. Fu and R. Guoguang "DC
micro-grid simulation test platform", Proc. 9thTaiwan Power Electron. Conf.,
pp.1361 -1366 2010
• [2] S. Morozumi "Micro-grid demonstration projects in Japan", Proc. IEEE
Power Convers. Conf., pp.635 -642 Apr. 2007
• [3] YUAN Vue, LI Zhenjie, FENG Yu. "Development Purposes, Orientations
and prospects of microgrid in China". Automation of Electric Power Systems
(in Chinese), voU, pp.59-64., Apr. 2010.
• [4] LU Zongxiang, WANG Caixia, MIN Y ong. "Overview on microgrid
research". Automation of Electric Power Systemsvo1.l9, pp.lOO-l06, Apr.
2007.
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