College of Engineering and Architecture

Using Informationto Increase

Power Reliability andReduce Vulnerability

Anjan BoseWashington State University

AAAS Annual MeetingSeattle, WA

February 12-16, 2004

College of Engineering and Architecture

North American Power Grid

College of Engineering and Architecture

College of Engineering and Architecture

West European Power Grid

                                                                                                                                                

College of Engineering and Architecture

Communication for Power System

Control Center

RTU RTU RTU

Third Party•Analog measurements•Digital states

College of Engineering and Architecture

Substation Automation

• Many substations have Data acquisition systems at faster rates Intelligent electronic devices (IED) Coordinated protection and control systems Remote setting capabilities

• Data can be time-stamped by satellite

College of Engineering and Architecture

Evolution of Communication System

Control Center

RTU RTU RTU

•Utilizing existing system•Building a new one

Networks

College of Engineering and Architecture

Monitoring the Power Grid

• Alarms Check for overloaded lines Check for out-of-limit voltages Loss of equipment (lines, generators, feeders) Loss of communication channels

• State estimator

• Security alerts Contingencies (loading, voltage, dynamic limits) Corrective or preventive actions

College of Engineering and Architecture

Control of the Power Grid• Load Following – Frequency Control

Area-wise Slow (secs)

• Voltage Control Local Slow to fast

• Protection Local (but remote tripping possible) Fast

• Stability Control Local machine stabilizers Remote special protection schemes Fast

College of Engineering and Architecture

• Must monitor and control over wide range of time scales for control decisions (hybrid control)• Slow response (10s of seconds): Transformer, shunt

switching, etc.• Medium response (seconds): load following, etc.• Fast response (milliseconds): protection, stabilizers, etc.

Generators

Gen

Gen

Gen

Load(customers)

Controller Controller

… …

College of Engineering and Architecture

Reliability of the Power Grid

• Generation Capacity must be greater than load• Transmission must not be overloaded• Voltages must be within limits• Must be able to withstand loss of generator• Must be able to withstand loss of transmission line• Must not lose stability during short-circuit• Must be able to withstand loss of communication

channel

College of Engineering and Architecture

Vulnerability of the Power Grid

• Acts of Nature - Equipment failures Probability low of contingencies outside design

criteria

• Acts of Man Simultaneous outages of power equipment

(sabotage, bombing, etc) - knowledge is key Simultaneous outages of communication

equipment Sabotage through communication system

College of Engineering and Architecture

Status Information & the Power Grid

• Deregulation is adding many more participants to the grid!

• Resulting changes in status monitoring requirements Many more devices More general topology and connectivity Much more heterogeneity involved Existing hardwired, hierarchical structure does not

suffice!• New services require more quantity, timeliness, …

Local extreme today: substations tracks all its devices Other extreme possible: adjacent grids track some of

neighbors’ internal status or derived (computed) values

College of Engineering and Architecture

Communication for Power System (proposed)

Networks

Substation

Substation

Substation

Control Center

Third Party

College of Engineering and Architecture

•Connected with network: data provider consumer•Peer to peer: publisher/subscriber•Benefits: Flexible, expandable, transparent to user, fault tolerance, resource sharing, etc.

Substation

network

Datacontrolcenter

Traders

PowerPlant

Substation

PowerPlant

Data

Data

Data

Data

Data

Network

Publishers Subscribers

substation

gen. plant

othercontrolcenter

ISO

traders

Othercontrolcenter

College of Engineering and Architecture

GridStat ArchitecturePublishers Subscribers

…Gen

Controller

QoS ManagerQoS Manager

S

S

S S

S

Controller

Load Following

…S Other Services

…

College of Engineering and Architecture

GridStat in a NutshellMiddleware≡ high-level software to make programming distributed computing systems easier: CORBA, .NET, Java RMI.

• Publish-subscribe architecture Simple, CORBA-compliant APIs for both

publishers and subscribers: interoperability Subscribers have transparent cache of latest

status value: ease of programming “Cloud” of internal servers managed for QoS:

resilience Optimizations for semantics of status items:

efficiency

College of Engineering and Architecture

GridStat Capabilities Today

• Quality of Service Provided: Timeliness and Redundancy

• Prototype capabilities today Hierarchy of QoS Managers performing the

allocations Publisher delivery rate and redundancy QoS

requirements satisfied Optional notification callback to subscriber of

QoS violated Rich GUI environment Configuration tools to set up different

configurations rapidly

College of Engineering and Architecture

Basic Functionality

Publisher 1

Publisher 2

Subscriber 1

Subscriber 2

QoS Management

QoSRequirements

QoSRequirements

QoSRequirements

QoSRequirements

Control

College of Engineering and Architecture

QoS Specification: Who Sets What?

Who sets what?

Publisher Subscriber QoS Manager

Fault Tolerance

Sometimes Yes

Timeliness Specifies rate of pub

Yes Yes

Priority Yes

Security Yes (ACL) ?? Maybe ??

Yes

College of Engineering and Architecture

GridStat Implementation

College of Engineering and Architecture

Some Observations

• Deregulation dependent on increased movement of data (markets, metering, billing, etc.)

• Operational reliability dependent on better monitoring and control

• More communication and computer systems

• Information security becomes more important while physical security remains an issue