college of engineering and architecture using information to increase power reliability and reduce...
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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
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
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