ee392n lecture two: the power grid and grid communications · 2011. 4. 5. · – intelligent...

EE392NLecture Two:

The Power Grid and Grid Communications

April 4, 2011

Dan O’Neill

Seminar Course 392N ● Spring2011

ee392n - Spring 2011 Stanford University

1Intelligent Energy Systems

The Energy Grid

• Last time…• Intro to the grid

– Traditional grid– Change– Intelligent energy system

• Communications background– Grid communications today– Future requirements– Alternatives



Last Time:Intelligent Energy Systems

• Nearer term evolution of the grid leading to the Smart Grid

• Look at intelligent energy systems from a systems point of view

• Focus on information and management

Time



Traditional Grid

Intelligent Energy Systems

Smart Grid

Backup: Smart Grid

The essence of this vision is “a fully–automated power delivery network that can ensure a two-way flow of electricity and information between the power plants and appliances and all points in between”. The three key technological components of the Smart Grid are distributed intelligence, broadband communications, and automated control systems.



The Energy Grid






Traditional Grid

• Worlds Largest Machine!– 3300 utilities– 15,000 generators,

14,000 TX substations– 211,000 mi of HV

lines (>230kV)– SCADA control– Mostly unidirectional

• Capacity constrained graph



Interconnect



The Energy Grid

8

Distribution

Conventional Electric Grid

Generation

Transmission

Load

Data

Management and ControlCommIT



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Three Planes

• Electrical power– Supply(t)=Demand(t) – Real and reactive power

• Management and Control (MC)– Local protection systems– SCADA: Supervisory Control and Data Acquisition

• Data systems– Billing



Backup: Supervisory Control and Data Acquisition

• Collects, processes and displays system data– Coordinates resources– Displays problems

• Converging with standard– Communications– IT


Intelligent Energy Systems 10

• Incorporating renewables – supply(t)• Replacing old equipment, $1.5T

– Electrical efficiency – Reliability – Embedded smarts

• Reducing operating costs– Excess capacity: Reserves– Bottlenecks: Transmission

• Deregulating

The Traditional Grid is Changing



$850B - grid$650B - users

Nearer Term Initiatives

• Renewables• Demand Response• Grid optimization• All drive a need for IT and communication systems



Renewables

• System characteristics– Time varying – Inherent randomness!

• Issues– Centralized/uGrids?– Grid control and

stability– Communications– Supply(t) < Demand(t)



Renewables: The System Problem

National Renewable Energy Laboratory



15

Demand Response

• A method to reduce peak to average using variable pricing – Static - Look ahead– Dynamic pricing – Real time– Direct Load Control (DLC) – Utility directly reduces load– Interruptible tariffs – Large customers only

• Many issues– How communicate?– Consumer response?



Demand Response

Campus and Buildings Home

•AMI •EMS•Smart devices

Whirpool Corp. made a public commitment to ship in 2011 a

million dryers ready to plug into a smart electric grid , if

communication standards



Grid Optimization

• Adjusting – Supply(t)– Connectivity

• Transmission routing• Distribution Automation

– Aggregating DR users• Commercial buildings



The Energy Grid






MC and Data Flow

19

Generators

Transmission 275-400’s KV

Industrial Commercial Business Residential

Distribution 10-20KV

ISO

Substations

Fiber and uWave

Manual

Slow speed wired and wireless/ nothing

??????



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Grid Communications

•Separate systems•Reliable •Secure

•Integrated

•Not integrated with existing communications systems

•Not visible on the Internet



Intelligent Energy Network

21

Conventional Electric Grid

GenerationTransmission

DistributionLoad

Intelligent Energy Network

energy subnet

Conventional Internetee392n - Spring 2011 Stanford University


Cisco will talk about this…

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Intelligent Energy Systems Communications

• Near Future– Transmission Area

Network (TAN) – Field Area Network

(FAN) – Neighborhood Area

Network (NAN) – Home Area Network

(HAN)



Comm. Performance IssuesBandwidth Latency Reliability Comments

Field .5 /20Mbs 10us-1 sec 99.99 Control and SCADA

Neighborhood .1/5Mbps <50 msec 99.99 AMIHome 1-10Kbps >10 sec ? EMS

HAN•Separate energy net from home datanet?•Can use Internet?

Latency•Transmission•Queuing

Comments:



Alternative StandardsZigbee WiFi 4G/WiMax PLC comments

Field XNeighborhood MESH X Europe 3 vs 50Home MESH MESH Femto? XSmart Meter X X X X



Smart Grid Comm Overview

• Many competing ideas and standards

• Issues– Performance

(interference)– Latency– Security



ZigBee• ZigBee smart energy 2.0

standard (HAN)– ~100ft– ~250Kbs

• Many suppliers and very inexpensive

• Not compatible with PLC• Open upper layers - Flexible• IEEE 802.15.4 Physical and

Data link layers– Mesh– 900Mhz/2.4Ghz DS-Spread

Spectrum



IEEE/NIST interface and data standards: Converged USNAP and EPRI home standard

Power Line Communications• HomePlug Green Phy

– 10Mbs– IP

• Uses the AC lines– Historical use in Transmission– Distribution for AMI 500Kbs– Use in Europe is diff. than US

• HAN applications (Media) – 10-200Mbps, OFDM– Multiple standards

• Questions– Reliability (Not a mesh)– Interference– Privacy



WiFi

• DAN – Mesh– 802.11a backhaul– Upper layer routing

optimization and security• HAN - coexistence?

– Interference– Reliability– Security

• IEEE standard 802.11x– 2.4(g) /5Ghz (a), OFDM– Up to 200Mbs

Tropos



3G/WiMax/4G

• FAN (EPRI)• Issues

– Priority - latency– Reliability – dropped calls– Cell phone companies

• Roughly– 100Mbs downlink– 50Mbs uplink

• IEEE standards– OFDMA– MIMO



Communications Challenges

• The last “hop” and in the home• Distribution system network (transformers and EV’s)• Reliability and security• Hierarchical decomposition of functions and applications

=> grid management– IT structure– Communications systems

• Integration with Internet?



Next Week

• Dimitry will talk on Control and Monitoring Basics



ee392n lecture two: the power grid and grid communications · 2011. 4. 5. · – intelligent...

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