A Smart Grid Architecture for Meeting Future by sdfwerte

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									            A Smart Grid Architecture for Supporting Open Access to Power Grids

                                                      H. W. Ngan
                                      The Hong Kong Polytechnic University

Abstract -- Smart Grid is the application of modern             under regulation. Not only that a new regulatory
information, communication, and electronics technology          paradigm for the grid is emerging, the way the grid
to the electricity delivery infrastructure. It has been shown   is designed and operated can no longer fulfill its new
that traditional grid design for securing reliability and       role such as to allow open access and allocated
trade-offs between lines and plants economically can no
                                                                available capacity for all generators in a non-
longer satisfy new role of power grid in competitive
market environment. Following deregulation of the               discriminatory manner. The new role of the grid has
electricity supply industry, the role of power grid has         extensive implications for its design, operation and
changed profoundly including a need to provide open             management.
access to all generators of large and small scale of which
the grid is simply not designed for. In the paper, some
key elements of smart grid and its architecture are
outlined so as to show how it allows for a multitude of
energy services to support open access to the grid in a
competitive power market environment.

Keywords: Smart Grid, Power Market, Open Access


                   I. INTRODUCTION
     Power Grid has long been regarded as the
backbone providing vital links between electricity
producers and consumers. In its traditional form, the
power grid by design is based on slow responding                            Figure 1 Smart Grid Application
mechanical switches and without sufficient                                        (Source from EPRI)
intelligence to monitor and control the substation
components fast enough to cope with the dynamic                     In this paper, the basic problem due to changes
changes ahead. Since the late 20th century, many                on the role of the grid and how smart grid helps to
technological innovations are emerging paving the               solve the problem will be discussed. Architecture of
ways to develop the power grids towards the end                 the smart grid and its strategic implementation are
that meets the future needs of different stake holders          outlined.
smartly. The interactions among all parties
concerned are infused into the power grids under the
smart grid vision underpinned by the bold                          II. NEW ROLE OF TNANSMISSION GRID
programme of research and development taken place
in the U.S. and Europe. Power grid is expected to be                Over the last 20 years, changes in the basic
transformed into one with "smarter" capabilities that           structure of the electricity sector have created
can integrate a multitude of distributed energy                 challenges to the traditional operation of power
resources, uses solid state electronics to manage and           systems. Changes in the technology of electricity
deliver power, and employs automated control                    generation have gradually led to the opening of
systems and so termed "smart grid" with typical                 electricity generation to more competition. Open
applications at all level as shown in Figure 1.                 access to the transmission grid for generation from
                                                                new technologies such as combined cycle
     In an open competitive environment, the                    combustion turbines, cogeneration and wind power
structure and regulation of the electricity industry            becomes more urging in need.
has changed profoundly. The core of change
involves allowing competition in the construction
                                                                    When the power system is in vertical integration
and operation of power generation and leaves the
                                                                mode, transmission system operators are primarily
transmission of that power over the grid remain
                                                                responsible for maintaining the delicate balance of
                                                                                                            1
supply, demand, and transmission capability, second                                                                                                                         A. Advanced Metering Infrastructure (AMI)
by second. Transmission system operations are                                                                                                                               AMI systems support two-way communications with
organized into "control areas", whose control area                                                                                                                          customers while supporting secure, encrypted, and
operators must continuously balance electricity                                                                                                                             reliable system wide communication for distribution
demands with electricity generation while keeping                                                                                                                           automation represent an enabling foundation for the
power flows over individual transmission lines                                                                                                                              smart grid. Increasingly, utilities will engage
within specific limits for system operating reliability.                                                                                                                    customers through two-way energy/information
Upon generator deregulation, the grid is required to                                                                                                                        portals and through other automated means. This
provide open access for all generators which are                                                                                                                            could, in the future, create a fully functioning
smaller in capacity but more efficient and distributed.                                                                                                                     marketplace with automated computer agents tied to
However, the grid is really not designed to receive                                                                                                                         home automation systems responding to price
power in small or large capacity at what the grid sees                                                                                                                      signals.
as the user end of the system. Also, the consumer
devices are almost passive for they take as much
power as they need from the grid and do not                                                                                                                                 B. Distribution Management System
otherwise communicate with or change in response                                                                                                                            The focus of achieving cost savings and improved
to grid conditions.                                                                                                                                                         customer service lies in distribution management
                                                                                                                                                                            systems (DMS) that provide real-time response to
                                                                                                                                                                            adverse or unstable conditions. In a smart grid,
                        III. SMART GRID ARCHITECTURE                                                                                                                        software programs must provide self-healing
                                                                                                                                                                            functionality in order to instantly detect and react to
   To cope with the changes, the smart grid vision                                                                                                                          power disturbances with minimal customer impact.
for the market has evolved in recent years through
the work of various consortiums and early adopter                                                                                                                           C. Distribution and Substation Automation
efforts at utilities. The essence of the smart grid lies
in digital control of the power delivery network and                                                                                                                        The smart grid will require functionality such as
two-way communication with customers and market                                                                                                                             control center supervision, area-wide solutions and
participants. The grid infrastructure as illustrated in                                                                                                                     visualization     with     centralized       modeling.
Figure 2 provides an overall view of the changes.                                                                                                                           Implementations      should      leverage     installed
                                                                                                                                                                            infrastructure and deploy a model-based, scalable
                                Today                                                     Smart Grid                                                                        approach to automation, providing a more practical
                                                                                                                                                                            and cost-effective solution that ensures that current
                                                                                                                                                  Energy Management
                                                                                                                                                                            hardware isolated and disconnected restorative grid
                        Customer                                                     Customer                                                          Systems,
                                                                                                                                                                            technology gives way to true reactive, software-
                                                            Little Data Exchange
                                      Passive Operation




                         Loads                                                        Loads                                                         Smart Meters,
                                                                                                                                                  Automated Demand
                                                                                                                                                      Response
                                                                                                                                                                            driven intelligence with central or distributed control.
                                                                                                                                                       Microgrids,
Grid Infrastructure




                          DER
                                                                                                                        Enhanced Data Exchange
                                                                                                  Distributed Control




                                                                                       DER                                                       Ancillary Services (e.g.
                      Distribution
                                                                                                                                                      VAR control)          D. Simulation and Optimization
                                                                                   Distribution
                                                                                                                                                                            Through advanced simulation and optimization
                       Substation                                                                                                                Distribution Automation    schemes, the utility of the future will reap cost
                                                            Basic Data Exchange




                                                                                                                                                                            savings and operational performance benefits not
                                      Centralised Control




                      Transmission                                                  Substation                                                   Substation Automation
                                                                                                                                                                            previously achievable. The ability to analyze
                                                                                   Transmission                                                  Wide Area Monitoring
                        Central                                                                                                                       Systems               automation and budget scenarios will drive smart
                       Generation
                                                                                     Central
                                                                                    Generation
                                                                                                                                                                            grid planning and performance even further.

                                                                                                                                                                            E. Enterprise Business Intelligence
                                     Figure 2 Changes on Power Grids                                                                                                        Overlaying these intelligent distribution system
                                                                                                                                                                            technologies is the enterprise business intelligence
The new infrastructure will allow for a multitude of                                                                                                                        derived from system data and analytics. This key
energy services, markets, integrated distributed                                                                                                                            piece of smart grid operations provides the high-
energy resource, and control functions. The basic                                                                                                                           level presentation and ability for interpretation of
structure of a smart grid architecture consists of the                                                                                                                      grid data and decision support through real-time
following elements:                                                                                                                                                         dashboards and historical analysis. Data is


                                                                                                                                                                                                                                  2
transformed into actionable information and a bridge    responsible to install communications, control and
is built between IT and operations.                     switching equipment on customer owned generators,
                                                        and provide maintenance and fuel. In return
   The key attributes of the smart grid can be          customers allow the utility to run generators up to
summarized as listed below:                             400 hours per year. The program aims to supply 100
                                                        megawatts of peaking capacity and now has 38 MW
 • The grid will be ‘self-healing’ in the sense that    on line or under construction.
   sophisticated grid monitors and controls will
   anticipate and instantly respond to system
   problems in order to avoid or mitigate power
   outages and power quality problems.
 • The grid will be more secure from physical and
   cyber threats. Deployment of new technology
   will allow better identification and response to
   manmade or natural disruptions.
 • The grid will support widespread use of
   distributed generation. Standardized power and
   communications interfaces will allow customers
   to interconnect fuel cells, renewable generation,
   and other distributed generation on a simple
   "plug and play" basis.
 • The grid will enable customers to better control        Figure 3 Architecture Enables the Smart Grid
   the appliances and equipment in their homes and                     (Source: from EPRI)
   businesses. The grid will interconnect with
   energy management systems in smart buildings            Real-time monitoring – Sensors are embedded
   to enable customers to manage their energy use       throughout the grid from generators and power lines
   and reduce their energy costs.                       through substations and feeders. The real time
                                                        information stream enables a multiplicity of
                                                        functions including rapid diagnosis and correction of
    IV. CASES ON POWER MARKET SUPPORT                   grid problems, and measurements of transmission
                                                        lines to determine when they are reaching capacity –
                                                        Lack of such information means transmission
   In an open competitive power market, existing        operators must under-use wires to make sure they do
power plants are allowed to change their output level   not overload. Real-time readings will allow fuller
in a time frame of 10 minutes interval, often           utilization of transmission lines, improving grid
dramatically altering the direction of power flows      reliability and economics. For instant, Bonneville
over the course of hours. Power traders can agree to    Power Administration (BPA) has pioneered the
sell power from a plant to a load far away. We have     Wide-Area Measurement System (WAMS) a
to create a grid which has high interoperability with   network of sensors located at substations which
rich support of information technology. It allows       provide real-time updates on the Bonneville grid 30
multiple networks, systems, devices, applications or    times per second. Updates are coordinated through
components to exchange information and to use that      global positioning satellites and sent to a central
information effectively for action with little or no    computer that analyzes disturbances, provides
human intervention. Figure 3 illustrates the            operators with solutions and monitors the results.
architecture of the power grid for supporting           WAMS systems now operate throughout the western
applications at all levels, essentially a high          U.S. Similar monitoring networks are being installed
throughput of electricity, money and information as     in the Northeast in order to avoid a repeat of the
required in a competitive market.                       August 2003 blackout.
  One example of illustration can be referred to the       Demand Response – Two-way communications
Portland General Electric’s Dispatchable Standby        between power providers and customers opens the
Program in which it networks on-site backup             way to flexibly adjust power to grid conditions. This
generators in sites such as office buildings and        “demand response” contrasts with the traditional
public facilities and make them as standby capacity     utility system in which supply adjusts to meet all
to meet peak power demands. The utility is
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demands. Customers receive financial incentives for
cutting power demand at times the grid is under
pressure. They can do this by dropping consumption                      VI. REFERENCES
or replacing grid power with distributed generation.
Demand response holds power bills in check by            [1] Moore D. and McDonnel D. "Smart Grid Vision
reducing the need for peak power generation and              Meets Distribution Utility Reality", Report of
wires infrastructure, the most costly pieces of the          McDonnel Group, March 2007.
power grid because they are used the fewest hours. It    [2] Fox-Penner, P., "Rethinking the Grid: Avoiding
could also be employed to help prevent blackouts             More Blackouts and Modernizing the Power
and brownouts. For example, BPA operates a                   Grid will be Harder than You Think", The
Demand Exchange system which uses wireless and               Electricity Journal, 205, pp. 28-42
web technologies to alert participating customers        [3] Ngan, HW "Smart Grid Technology for Power
when the power system is expected to be under                Market Development", Proceedings of the 6th
stress, for example, when arrival of a cold front is         Annual Power Symposium 2007", Power and
forecast. Customers respond with bids for demand             Energy Section of the IET Hong Kong, June
reductions and receive financial compensation in             2007, Invited Paper No. 1, pages 1-5.
return. Demand Exchange is being employed on the         [4] Potocnik, J., "European SmartGrids Technology
Olympic Peninsula to shave peaks in an effort to             Platform, - Vision and Strategy for European’s
defer the need for expanded transmission capacity.           Electricity Networks of the Future" EUR 22040,
BPA is also signing up local backup generators to            2006
offset peak demands.                                     [5] Mazza, P., "Powering up the Smart Grid: a
                                                             Northwest Initiative for Job Creation, Energy
   Smart meters – Smart meters record power usage            Security and clean, Affordable Electricity," July
digitally by time of day and report it by                    2005.
telecommunications. This enables pricing that varies     [6] Hakvoort, R., "Technology and Restructuring
between high and low demand periods, providing               the     Electricity     Market",    International
economic incentives to shift power use out of peaks.         Conference on Electric Utility Deregulation and
Northwest utilities including Puget Sound Energy             Restructuring and Power Technologies, 2000, 4-
and Avista have made large smart meter                       7 April, 2000, pp. 390-395
deployments. Following the 2000-2001 West Coast
power crisis California instituted a Dynamic Pricing
Pilot to test the effects of time-based pricing on                       VII. BIOGRAPHIES
peaks. Starting in July 2003 smart meters were
installed at 2,500 customer locations and several rate
                                                                   H.W. Ngan received his M.Sc in 1979,
structures were tested. Peak reductions on hot                     MBA in 1985 and PhD in 1993 from the
summer days when the grid was most stressed                        University of Aston, University of Hong
reached 13%. With a large majority of participants                 Kong and University of Strathclyde
expressing a desire to continue, the program remains     respectively. He has been elected as Fellow of the
ongoing.                                                 Institution of Engineering and Technology (FIET),
                                                         and Senior Member of the Institute of Electrical and
                                                         Electronic Engineers (SrMIEEE). He served as
                V. CONCLUSION                            Chairman of the IEEE Hong Kong Section in 2003
                                                         and 2004. He is now the Associate Professor in the
   The smart grid, as outlined in this paper, is         Department of Electrical Engineering, the Hong
developed towards the architecture with high             Kong Polytechnic University. His current research
interoperability based on application of digital         interests include Power Market Reform and
information, communication and power electronic          Simulation, Smart Grid Modeling and Control,
                                                         Sustainable Energy Development and Energy Policy
technologies. It assumes the new role of fulfilling
                                                         Planning.
the power flow requirement by allowing open access
and facilitating competitive market activities to be
carried out effectively. Applications of the smart
grid infrastructure to meet the needs of the future
power market and to support its development are
presented in the paper as well.
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