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Wednesday, October 09, 2013
Smart Grids: The Path Going Forward,
Dr. Sameh El Khatib, and Dr. Amro FaridEngineering Systems and Management Dept., Masdar Institute
3rdSMART GRIDS AND SMART METERS SUMMIT
2425 SEPTEMBER 2013, ABU DHABI, U.A.E.
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Introduction
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Making grids smarter is a required transformation fueled by
several drivers characterizing current factors & inclinations
Wednesday, October 09, 2013
Environmental & sustainability
concerns
Energy demand growth
Electrified transportation
Aging power systems infrastructures
Empowerment of demand-side
Operational challenges in terms of
requiring significantly higher levels of
regulation and ramping capacity
New flow patterns at the distribution
level which necessitate drasticchanges to the protection, distribution
automation, and voltage/VAR
management
Limited dispatchability and increasedintermittencies, which result in
increased ancillary services
Monitoring and automationdeficiencies leading to inadequacies
in meeting increased loads on
distribution networks
Need for Smarter GridsEffect on Power SystemsFactors &
Inclinations
Control has to rise to the occasionand counter a significant number of
these challenges
Advances required in sensing
technologies to make new
information available about various
aspects of the grid
Progress in communication
technologies needed to make datadynamically available at pertinent
locations within the grid
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A Smart grid is an end-to-end cyber-enabled electric power
system bringing control and automation to center stage
Wednesday, October 09, 2013
The Essence of Smart Grids is to
Enable integration of intermittent
renewable energy sources;
Help decarbonize power systems;
Allow reliable and secure two-way
power and information flows;
Promote energy efficiency;
Facilitate effective demand management
and customer choice;
Provide self-healing from power
disturbance events;
Allow power systems to operate
resiliently against physical and cyber
attacks
Smart Grids Facilitate
Decision making, in an automated manner,
from seconds to seasons, at desired, new,
and distributed locations
Opportunities for control:
Reducing consumption Exploiting renewable sources
Increasing reliability and
performance of the transmission
and distribution networks
Demand response thus allowing load to be
shaped rather than followed
The use of plug-in electrical vehicles as
dispatchable assets aiding distribution
system
The usage of energy storage technologies to
be used as alternatives to fossil fuel-based
spinning reserves.
Vision for Smart Grids
Closing loops in power systemswhere they have never been closed
before, across multiple temporal andspatial scales
Enable decision making underuncertainties, across broad temporal,geographical, and industry scales
Meet desired emission andsustainability targets whilemaintaining accepted levels ofreliability
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In this talk we will discuss the role of control systems in the
evolution of Smart Grids and touch upon the way going forward
Wednesday, October 09, 2013
A look into theFuture
Baseline
Going Forward
Introduction Presents an overview of Smart Grids and their role in current power systems
Discuss drivers for change that pave the way for a paradigm shift in the electric grid
Present different scenarios of Smart Grid evolution that might emerge in the future along with researchchallenges associated with such scenarios
Highlight practices in current control systems illustrating the roles of control in power systems such as
power balance, frequency regulation, and reactive power control
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Baseline
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The challenge of power systems is the requirement of interrelated
tools of dynamical systems analysis, control, and optimization
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Historical and current practices in power
grid control focus on four major topics:
Generation power set point selection
through market operations or economic
dispatch
Primary and secondary control for frequency
regulation and power balance
Reactive power control for regulation of
voltage magnitudes
Communication and sensing technologies to
support these control functions.
Challenging Characteristics of Power Systems
The transfer of power through long-distance, high-
voltage transmission induce dynamic
electromechanical coupling on a nearly continental
scale of power grids
The mix of near-speed of- light electrical phenomenawith mechanical response of generators and load
means that major disturbances can propagate over
long distances, at very high speeds
At slower timescales, the characteristics and cost of
grid operations depend heavily on the geographic
and cost mix of generation and load which implies
that considerable attention is devoted to periodicupdates of the set points of many thousands of
pieces of equipment throughout the network
Control for the grid is not only a problem of feedback
design to achieve regulation, desirable dynamic
response characteristics, or both, but also the
selection of the quasisteady state or steady-state
operating point as determined by the grids nonlinearpower flow equations of optimality and reliability
equilibrium
Control as interpreted in
power systems applications,
must be understood in a
very broad context
1
2
3
4
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Generation dispatch has a huge impact on cost of power
production inducing the use of periodic optimization to dispatch
Wednesday, October 09, 2013
1 Generation power set point selection through market operations or economic dispatch
Load treated as an uncontrolled,exogenous input, and electricutilities have been operated withan assumed obligation to serve
The sum of the power output levels ofgenerators must be regulated to matchthe total load plus losses on the grid
Evolution of complex electricitymarkets that are based on
power pools governed byindependent system operators
High dimensional regulation problem, inwhich a very large number of generatingunits are required to stably regulate tonew set points of desired megawatt (MW)
power output, while maintaining reliable
system operation
Situation Contro l Requirement
Historic
Cur
rent
Solut ion Method
Solved on a periodic basis,on timescales of minutes asan optimization problem, toselect desired set points for
generator output
Solved as a game where thepool receives offers to selland bids to buy electricity
Pool solves an optimization
problem that minimizesoffered generation costs andmaximizes buying bidssubject to generation,transmission and secur i ty-cont ingency con stra in ts
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Smart Grids assist in the control challenge of generating units
stabilizing to their set point while maintaining reliable operation
Wednesday, October 09, 2013
1 Generation power set point selection through market operations or economic dispatch
Control Challenge at this Level
Determination of system-wide stability properties is
heavily influenced by the nature of both continuously
acting and discrete control systems throughout the
network
The requirement of reliability adds a huge number ofscenario-based analyses (N1) secure
From a control analysis standpoint, this specification
is a large-scale robust stability requirement: stability
must be maintained for every member of a family of
systems, each representing a different discontinuous
structural change to the nominal system
A typical dynamic model for a power system is a
mixed system of nonlinear differential-algebraic
equations governing its dynamic response.
These requirements bring in much more complex,
large-scale system challenges inherent in operating
the power grid, as their satisfaction involves not only
the control systems of the individual generators, butalso of the transmission network, and of a wide range
of other grid equipment and load characteristics.
Smart Grids Will
Allow future power grids to greatly expand the
numbers and classes of equipment productivelycontributing to control through enhanced
communication and computation
Lead to more distributed control involving larger
numbers of contributors which carry great promise to
improve the stability, reliability, and economy, and to
reduce environmental impact of grid operation.
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Smart Grids also increase price elasticity of demand by facilitating
real-time engagement of retail consumption in periodic markets
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1 Generation power set point selection through market operations or economic dispatch
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Stably regulating frequency reflects the objective to reliably
maintain the instantaneous balance between generation and load
Wednesday, October 09, 2013
2 Primary and secondary control for frequency regulation and power balance
Power Systems Fact 1
At bus locations with generators attached, the inherent physics of
synchronous machines dictate that the electrical frequency of the
generator voltage and the mechanical rotational speed of the
generator are locked in fixed proportion to one another so that
variation of frequency at these locations directly reflects deviations
in rotational speed away from the desired steady state.
Power Systems Fact 2
The nature of alternating current (AC) power transmission is such
that a synchronous region is in exact equilibrium only if electrical
frequency is equal at every node in the network (i.e., all
interconnected generators rotating at the same nominal speed).
Underlying Grid Control Problem
The requirement for stable dynamic performance, such that any deviation of the independent
frequencies of generators converge to steady state in a stable fashion
The quasisteady state regulation requirement that the shared synchronous frequency (equal at all
nodes in equilibrium) be regulated to a tight band about its desired 60 Hz (hertz) value
Primary
Control
Secondary
Control
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Primary control is a corrective feedback while secondary control
acts on a slower timescale over a wider region
Wednesday, October 09, 2013
2 Primary and secondary control for frequency regulation and power balance
A corrective feedback (often just a proportional gain) that incrementally changes a generators
power output in response to locally measured frequency/speed error
Each time the generator receives an updated market command for a desired MW output, this
update is simply a new set point to the feedback control system. This feedback measures terminal
electrical power delivered and correspondingly adjusts the mechanical shaft power input
(typically through valves controlling gas, or steam, or water flow delivered to a turbine).
Acts on a slower timescale, over a wider region, by modifying a subset of generators power set
points in the region, with the objective of regulating a measured signal called the area control
error (ACE).
The ACE signal comprises a weighted sum of area frequency error and deviations from set point
(scheduled interchange) of powers on select transmission lines that carry major power flows
in/out of the region of interest (Automated Generation Control)
Primary
Control
Secondary
Control
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In addition to active power control/frequency regulation is the
control of reactive power for regulation of voltage magnitudes
Wednesday, October 09, 2013
3 Reactive power control for regulation of voltage magnitudes
Power Systems Facts
An important qualitative feature of power flow in a synchronous grid
can be observed when power balance equations are written in
sufficient detail to represent reactive power balance at buses and its
dependence on voltage magnitude variations
If reactive power drawn or injected into the network at a bus istreated as a control input, the coupling of this input to the response
of voltage magnitude at that bus is quite strong
The impact of reactive power injection at a specific bus on voltage
magnitudes at neighboring buses drops off quickly away from the
point of injection
The problem of regulating voltage tends to be a more localized
problem, with a controllable reactive source at a given bus being
responsible for regulating voltage magnitude to a desired set pointat that bus or at a nearby neighboring group of buses
Remarks
There is coupling between voltage magnitude
behavior to frequency and angle which can be
exploited to design stability-enhancing
supplementary controls
Some aspects of the voltage control problem can
be viewed as more localized, and therefore
perhaps less challenging than active
power/frequency control
However As new classes of customer equipment
become more widespread, the characteristics of
load response can change in ways that make
voltage stability problems more critical
Smart Grids promise to advance
reactive power regulation without
undesirable coupling with other
regulation mechanisms
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Key contributions anticipated from Smart Grids are enhanced high
bandwidth and wide-area communication for control functions
Wednesday, October 09, 2013
4 Communication and sensing technologies to support these control functions
Energy Management System (EMS): Describes a wide ranging suite of software and hardware that supports a regional
control center in managing the production, purchasing, transmission, distribution, and sale of electrical energyEMS
SCADA
PMU
RTU
PLC
Automated
Metering
DCS
Supervisory Control and Data Acquisition (SCADA) system: An umbrella term to describe the wide range of physical
measurement and communication systems supporting operator control of remote (or local) equipment, whether the
physical media be microwave link, f iber optics, or wire line, and whether the control operation is opening or closing anetwork circuit breaker or commanding a set point change to a generator.
Phasor Measurement Units (PMU): Synchronized PMUs provide measurements of the voltage and current
magnitudes and phase angles, precisely time synchronized across large geographic distances.
Remote Terminal Units (RTU): Special-purpose microprocessor-based computers that contain Analog-to-Digital
Converters (ADC) and Digital-to-Analog Converters (DAC), digital inputs for status, and digital output for control
Programmable logic Controllers (PLC) are used to implement relay and control systems in substations
Designed to upload residential and/or commercial gas and/or electric meter data.
Plant Distributed Control Systems: plant-wide control systems that are used for power plant automation and control
Description of High Level Critical Systems Forming the Architecture of Present Day Grid Control Operations
Power Systems use power line carrier (PLC), microwave, fiber-optic,
pilot wire and wireless as underlying communication layers
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Going Forward
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Global movement towards Smarter Grids is fuelled by four major
drivers
Wednesday, October 09, 2013
Driver Description
Environmental
Stewardship
Societys future energy choices will likely be dominated by environmental constraints and compliance with local,
national, and global initiatives
The global decarbonization of energy systems has been steadily advancing facilitated to an ever-greater degree by
electricity
Reliability in Responseto Growing Demand
Power systems infrastructure is vulnerable to increasing stress from the imbalance between growth in demand for power
and enhancement of the power delivery system to support this growth
The result is increasing power outages and power quality disturbances
Empowered
Consumers
Made possible through a combination of technological, social, and behavioral changes, all of which will allow loads
to be responsive to the grids needs
In several places across the globe, demand response might be the only available asset to cope with unprecedentedgrowth in the demand.
Electricity SectorRestructuring
In the past 15 years global electricity sectors have witnessed trends toward privatization, deregulation, restructur ing, and
reregulation
A new energy value chain is emerging as a result of new regulatory environments, new technologies, and new players that
encourage competitive markets.
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The challenges are formidable however such challenges place the
notion of smart grids at the core of the solution path
Wednesday, October 09, 2013
Driver Challenges
Environmental
Stewardship
In the context of renewables, limited dispatchability necessitates new solutions that do not lead to increased
ancillary services. Their intermittency introduces several operational challenges in terms of requiring significantly
higher levels of regulation and ramping capacity. They also introduce new flow patterns at the distribution level,
implying drastic changes to the protection, distribution automation, voltage management, and VAR management
Reliability in Responseto Growing Demand
Significant new loads on distribution networks, many of which are inadequate when it comes to monitoring and
automation, requiring a major overhaul of distribution systems across the globe
Large, distributed loads have to be coordinated with grid operation to manage highly complex interactions that arisefrom spatial and temporal imbalances between requirements versus what is available from the grid
Empowered
Consumers
Modeling of empowered consumers without violating privacy or security concerns. A stressed infrastructure implies
that with additional demand and intermittent generation, reliability is severely compromised. Innovative methods forachieving and ensuring power balance are needed
Electricity SectorRestructuring
With price-based mechanisms taking center stage for the transformation of demand into a flexible entity, the challenge that
emerges is how real-time price is to be determined, with changing grid conditions both in generation and in demand
Market power shifts and price abuse
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Policy, technological advances, standards, and interoperability are
key enabling factors facilitating movements toward Smart Grids
Wednesday, October 09, 2013
Technology
Policy
Interoperability
Enabling Factors in the Deployment of Smart Grids
Standards
Digital advances in information and
communication of varied aspects of the grid,
Innovations in power electronics that allow
bidirectional flow and advanced control of all
aspects of the grid
Blueprint for smart management (i.e., control)
of this information, enabling decision making at
all crucial spatio-temporal locations in the grid
It is important that components and subsystems
from different suppliers are based on open,
accessible interfaces and protocols
Without standards, the effort and expense of
product development and system integration are
increased
The importance of interoperable standards for
the Smart Grid is globally recognized
The Smart Grid is a systems of systems;
solutions are, and will increasingly be,
integrations of components, often from
different sources
The components in question are not just
physical products, but also communication
protocols, information and data models,
software implementations of algorithms, etc.
Recent policies in the U.S., China, India, E.U., U.K., and
other nations throughout the world, combined with
potential for technological innovations and business
opportunities, have attracted a high level of interest in
Smart Grids
Nations, that best implement new strategies and
infrastructure might reshuffle the world pecking order:
Emerging markets could leapfrog other nations
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A Look into the Future
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Smart Grid promises revolutionary changes to the generation,
delivery, storage, and use of electricity
Wednesday, October 09, 2013
Scenario Vision
Grid-scale real-time
endpoint-based control
Hundreds of millions of active endpoints: sensors, actuators, and communication devices are deployed at generators,
along transmission lines, at substations, in transformers, in distributed energy resources (DER) such as photovoltaics and
wind turbines, and in inverters, storage devices, electric vehicles, and microgrids
Millions of individual and institutional agents: stakeholders in the operation of the new power-ICT (information
communication technology) grid include industrial, commercial and residential customers, governmental and university
campuses, microgrids, utilities, power generators, energy services companies, and regulators
Dynamic pricing and
multiple-horizon power
markets
A radical market reform from the realization that both generation and demand are implicated in the need for reserves,
transmission line congestion, and voltage support, and thus both have a role in optimizing power system efficiency.
Full power market participation of both generation and loadsbe they large-scale centralized entities or small-scale
distributed entities. In other words, distributed loads and generation (e.g., rooftop PV, small wind turbines) have access to
high-voltage power markets on par with centralized generation and large wholesalers/load aggregators, while responding
to and affecting distribution network costs and power quality requirements.
Real-time, closed-loop,
demand response
Customer facilities integrate not just loads, but distributed generation and storage resources as well. All of these energy
assets are modeled with their dynamics and uncertainties formally captured and integrated with control and optimization
methodologies
Loads, storage, and generation resources, whether in homes, buildings, or industry, respond in real time to the state of the
grid, the variation of grid-level renewable generation, and other factors that traditionally were little more than disturbances
in old-style facility energy management
Renewable generation Active distribution systems and adaptive networks that differ from existing systems in four important aspects to be
discussed later
Smart meters, phasor measurement units,power electronics are the foundation on which
control can construct the future Smart Grid
1
2
3
4
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Understanding and modeling electricity user utility,in particular, the utility of new flexible loads suchas HVAC, EV battery charging, and other storage-like schedulable loads. This involves inter-
temporally sensitive dynamics because theservice rate at a particular time is a function of thepast consumption trajectory.
Distribution network costs and congestion willneed to be incorporated in prices available todistribution network-connected consumers andproducers
Modeling abstractions employed must capture thefollowing information:
o The market scenario characteristics,
o Power system physics,
o Critical smart grid-related technologies,
o Distributed loads and resources that mightenable significant social welfare gains.
Today, centralized generation is theprimary full market participant, engaged intwo-way communications with market
operators
Other generation and the consumer sectorcan provide information to the market butare generally not involved in bilateralmarket interactions
In the proposed dynamic pricing scenario we envision all players
being full market participants
Wednesday, October 09, 2013
2 Scenario: Dynamic pricing and multiple-horizon power markets
Market reform has occurred in the timescales onwhich markets operate. The cascadingtimescalesday-ahead, hour-ahead, minutes-
ahead, and seconds-ahead transactionhorizonswith separate, incomplete, and ofteninconsistent market mechanisms employed foreach, have given way to a broader and seamlessspectrum of market and reserve choices
The gap in timescales between market-basedreserve pricing and centrally coordinated reservemanagement has been bridged
Distributed coordination is now accomplishedwith dynamic models and optimization algorithmsacross a broad class of market- facing assets.
Buying and selling covers active as well asreactive power.
Scenario Detai ls Current Practice Challenges / Research Prospect s
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Electricity consumption and performance of a vastvariety of facility-based devices and systems mustbe modeled with specific attention to variousdynamical aspects.
Advanced forecasting methods for loads andweather
Including end-use sectors in Smart Gridengineering is the necessity of modeling peopleas consumers as well as facility operators andoccupantsas elements of control systems
Pricing structures, policies, algorithms, andconstraints to handle coupling of power flows andmarkets at timescales that have the potential to
cause instability
The consideration of real as well as reactivepower, bidirectional power flows, and multiple-timescale coordination, requiring fundamentaladvances in feedback/feedforward andregulatory/supervisory control strategies.
In comparison to the future vision, thestate of demand response today seemsantiquated
Implementing automated demandresponse today is complicated enoughthat only large facilities can directlyengage in program
The main challenge in scenario 3 comes from the lack of
appropriate equipment for automated demand response
Wednesday, October 09, 2013
3 Scenario: Real-time, closed-loop, demand response
Advanced control technologies ensuring thatfixed, schedulable, and curtailable loads arerecognized and modeled
Production from on-site renewable generationsources is forecast, incorporating dynamicuncertainty, and these forecasts inform thedemand-response strategy
Fast dynamic response enables facilities toprovide the full range of ancillary services,including spinning and nonspinning reserve,frequency regulation, and reactive power support
The sophistication of control technology hasreached a level that enables sites to be
dynamically aggregated and disaggregated forautomated demand-response (ADR) programs.
The development of plug-and-play energy assets.
Scenario Detai ls Current Practice Challenges / Research Prospect s
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Sensing, optimization, and control (SOC)algorithms must be designed in concert with anunderlying real-time communication andnetworking infrastructure
The actions of heterogeneous distribution systemsdevices with different response speeds need to becoordinated and adapted
An understanding of the spatio-temporal variationsand correlations in power flows on distributioncircuits resulting from massive spatially distributedgeneration capacity
Development of distributed control concepts suchas self-organization, cooperative control, and
virtual leader-follower architectures
Distributed state estimation methodologies canand should be developed, using the properties ofphysical distribution networks, cloud computing,and big data innovations to ensure safe islandingoperation and other requirements
At present, grids have a radial topology;their operation and protection schemesare simple and do not support directionaldiscrimination
There are very few intelligent devices(beyond radio- controlled relays andOLTCs)
Distribution network operations areplanned (open-loop) because changes indemand are relatively slow andstatistically predictable, and voltages arecoarsely regulated (the typical range is5%)
There is little measurement data available
in real-time to determine the operationalstate of distribution systems or theirequipment
Currently grids have radial topologies with simple operation and
protection schemes
Wednesday, October 09, 2013
4 Scenario: Renewable generation
Distribution systems will have massivepenetration of distributed generation integrated inboth medium-voltage (MV) and low-voltage (LV)grids. Distributed generation will be pooled asvirtual power plants, and their aggregated power
will be dispatched automatically
Microprocessor-based relays or intelligentelectronic devices (IEDs), will be installedthroughout distribution systems to integratemultiple functions (such as metering, protection,automation, control, and digital fault recording)
Smart distribution grids will have hierarchicalcommunication networks: wide-area networks(WAN), neighborhood-area networks (NAN), anduser-area networks (UAN).
Distributed systems will use distributed sensing,estimation, optimization, and control algorithms toallow massive penetration of distributedrenewables
Scenario Detai ls Current Practice Challenges / Research Prospect s
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Smart Grids Mean:
Massive penetration of renewable generation
Reliability of supply under all conditions
Consumer engagement and empowerment
Cost efficiencies for all stakeholders
The way forward span the full design space
The relevance and importance of control extends across bulk and distributed
generation, transmission and distribution networks, residential, commercial, and
industrial facilities, and power markets and regulators Novel control-related insights suggest that the architecture and partitioning of todays
power system can and should be radically rethought
The way forward is contingent upon targeted, intensive and collaborative research and
development in control science and engineering
In conclusion, control technologies can play a crucial role in
achieving the broad societal drivers for the Smart Grid
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More details regarding the presented scenarios can be found in the IEEE Control
Systems Society (CSS) document IEEE VISION FOR SMART GRID CONTROLS: 2030 AND
BEYOND
To get more details about this document and its authors please contact Dr. Amro Farid
The scenarios in this talk were based on the IEEE CSS document:
IEEE VISION FOR SMART GRID CONTROLS: 2030 AND BEYOND
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Thank You
Wednesday, October 09, 2013 Version 1
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