College of Engineering and Architecture Using Information to Increase Power Reliability and Reduce Vulnerability Anjan Bose Washington State University AAAS Annual Meeting Seattle, WA February 12-16, 2004

College of Engineering and Architecture North American Power Grid

College of Engineering and Architecture

West European Power Grid

College of Engineering and Architecture Communication for Power System Control Center 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 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 Load (customers) 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 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 Data control center Traders Power Plant Substation Power Plant Data Network PublishersSubscribers substation gen. plant other control center ISO traders Other control center

College of Engineering and Architecture GridStat Architecture Publishers Subscribers … Gen Controller QoS Manager S S S S S Controller Load Following … S Other Services …

College of Engineering and Architecture GridStat in a Nutshell Middleware≡ 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

College of Engineering and Architecture QoS Specification: Who Sets What? Who sets what? PublisherSubscriberQoS Manager Fault Tolerance SometimesYes TimelinessSpecifies rate of pub Yes PriorityYes SecurityYes (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