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Intelligent Distributed Autonomous Power Systems (IDAPS)

Saifur Rahman

Electrical Power Symposium 2006"From Tesla�’s AC Power System to Distributed Generation and Smart Grids"

November 10, 2006

Electrical Power Symposium 2006

Outline�• Complexity of Critical Infrastructures�• The IDAPS concept

�– Normal operating condition�– Outage condition

�• Enabling technologies�– Supply-driven-demand management�– Agent-based technology�– Web-based communication overlay architecture

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Complexity of Critical Infrastructures

Transportation

Government

Banks/Finance

Satellite

Electric Power

WALL ST.WALL ST.

Wall Street

Oil & Gas Production

and Storage

Water SupplyTelecom

Business

Emergency Services

Information


Critical Infrastructure Interdependency

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Problems

�• Nation�’s critical infrastructures have become very complex and interdependent.

�• Charles Perrow, in a Sept 2006 Spectrum article, suggests critical infrastructures can be made less of a target by design.

�• In other words, planners need to focus on distributed systems that are more resilient, thus easier to protect it against man-made and natural disasters.


DER technologies

�• Solar cells

�• Wind turbines

�• Fuel cells

�• Electric vehicles

�• Diesel gensets

�• Microturbines

�• Storage devices

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Enhancing resiliency of electric power supply with IDAPS

�“IDAPS�”IntelligentDistributedAutonomousPower Systems


Wholesale, Retail electricity markets vs the IDAPS Microgrid

G TWholesalemarkets D

Retailmarkets

G = GenerationT = TransmissionD = DistributionDER = Distributed Energy Resource

End-use customers

DERLoadLoadLoad

LoadLoad

DER

Agents

DERLoad

LoadLoad

DER

Agents

DERLoad

DER

LoadLoadLoad

DER

By design, the IDAPS is a specialized microgrid that is set up at the level of end-use customers to allow electricity trading among neighbors. �“Retail competition�”

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IDAPS cellular structure

Feeder line

Feeder line

agentsDistributionsubstation

High Voltage Power Line

IDAPS Cell

DER DER

DER

DER DER DER DER

DER DER DER DER

DER

agents

agentsDER

DERDER

DER


Two modes of IDAPS operation

�• Normal operating conditions

�• Outage conditions

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During normal operating conditions

�• The IDAPS structure is complementary to the main electricity grid.

�• Households or businesses can �– purchase electricity from the grid as usual �– purchase electricity from their neighbors

�• Customers can choose which of their deferrable demands will be serviced based on the real-time cost of electricity.


During outage conditions

�• An IDAPS cell will island itself from the grid and start to operate autonomously.

�• Critical loads will first be served by their internal sources, and any shortfall can be made up through open market purchases.

�• It is also possible to buy and sell electricity among different IDAPS microgrids.

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IDAPS operations characteristics

�• Supply-driven-demand management

�• Multi-agent technology

�• Web-based communication architecture


Managing demand-driven-supply Vs Supply-driven-demand

Demand-driven-supply in �“the Pool�”Offers from generators are based on the �“known�” demand.

Supply-driven-demand in �“IDAPS�”(deferrable) demand for electricity is met by available supplies.

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Supply-driven-demand management

�• An IDAPS cell will employ a bulletin board that represents an electricity marketplace for electricity buyers and sellers to transact business.

Bulletin BoardDG owners

Three-tier modelPrice

QuantityDuration

User console, which can be a computer or a panel on

the kitchen wall

DG ownersDG owners


IDAPS Agents

�• User agent

�• DER agent

�• Aggregation agent

�• Bulletin board agent

�• Database agent

�• Device agent

�• Control agent

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Multi-agent framework in IDAPS

DER

DER

DER

DER

DER

DER


Communication overlay architecture

�• The multi-agent framework calls for a messaging system capable of exchanging information and control data among various agents, DER devices and interfaces.

�• A web-based communication architecture such as web services will be used to ensure interoperability among equipment.

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Web services

�• Web services is a web-based and platform-independent protocol for exchanging structured information in a decentralized and distributed environment.

�• Web services utilize extensible mark-up language (XML) over HTTP.


Example of web service communications in the IDAPS environment

SOAP Response

<SOAP-ENV:Envelope><SOAP-ENV:Body>

<ns1:GetLineVoltagexmlns:ns1=�“http://www.idaps.org/DGMonitoring-

service�”<ns1:DGID>UNIT0012PV3kw</ns1:DGID>

</ns1:GetLineVoltage></SOAP-ENV:Body>

</SOAP-ENV:Envelope>

SOAP Request

DER Agents

<SOAP-ENV:Envelope><SOAP-ENV:Body>

<ns1:GetLineVoltageResponsexmlns:ns1=�“http://www.idaps.org/DGMonitoring-

service�”<return>117.3</return>

</ns1:GetLineVoltage></SOAP-ENV:Body>

</SOAP-ENV:Envelope>

- Clients Registry- Services Registry- Services Description- Public Interfaces

IP-based network

IP-based networkDER

Interface

DERInterface

*SOAP = Simple Object Access Protocol

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Communication medium required�• In order to utilize web services, at least one of the

following types of communication media must be available.

�– A wired local area network (LAN)

�– A wireless network based on 802.11 or 802.16


DER�’s must be IP addressable �• All DER units and electronic devices must have

communication interfaces and are addressable by IP addresses.

DERInterface

DERInterface

DERInterface

DERInterfaceDER

Interface

DERInterface

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IDAPS summary2 Layers: physical and cyber

User agent

Aggregationagent

DER agent

Control agent Bulletin board

Database agent

Device agent

DERInterface

DERInterface

DER agent

DERInterface

DERInterface


Case studies: an IDAPS microgrid in Blacksburg, Virginia

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Building an IDAPS microgrid from Scratch

In the simplest term, an IDAPS cell may consist of local generation sources and loads fed by one circuit from a substation transformer.

Data from a Virginia Tech Electric Service low voltage substation


Normal operating conditions

agents

DER

DER DER DER DER

Distributionsubstation


The IDAPS structure is complementary to the main electricity grid.

4pm-9pm1,500 kWh5-6 c/kWh

8pm-9pm3,000 kWh4-5 c/kWh

1pm-2pm400 kWh6-7 c/kWh

�…�…�…

8am-1pm2,000 kWh3-4 c/kWh

2pm�–4pm500 kWh2-3 c/kWhDurationQuantityPrice

Bulletin board

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Outage conditions

Distributionsubstation


An IDAPS cell will island itself from the grid and start to operate autonomously.

DER DER DER DER

DER

agents


Outage conditions

Once the fault is cleared, IDAPS will reconnect itself to the grid.

Now 1,500 kWh9-10 c/kWh


Now 400 kWh10-11 c/kWh

�…�…�…


Now500 kWh6-7 c/kWhDurationQuantityPrice

Bulletin board

Bidding process will start.DER DER DER DER

DER

agents

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IDAPS Contributions

�• The framework for harnessing �“customer-owned�”distributed generation units.

�• The novel �“supply-driven-demand�” management.�• The web-based communication architecture using

�“web services�” to ensure interoperability.�• IDAPS represents an autonomous reconfigurable

power system enabled by Cyberinfrastructure.


Contact Information

Name: Prof. Saifur RahmanAffiliation: Virginia Tech, USAPhone: (703) 528-5500Email: [email protected] site: www.ceage.vt.edu

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