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Power blackout a case for critical condition management

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critical condition management CCM applications detect, monitor, and guide human operators through …

critical condition management CCM applications detect, monitor, and guide human operators through
periods of abnormal operation. These applications have become more accepted
in process manufacturing, especially in the chemical and
petrochemical industries. The properties of these abnormal periods have
much in common with the details that have been reported thus far concerning
the Eastern US blackout of August, 2003

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  • 1. THOUGHT LEADERS FOR MANUFACTURING & SUPPLY CHAIN ARC INSIGHTS By Harry Forbes INSIGHT# 2003-37MP&H SEPTEMBER 10, 2003 The US Blackout of 2003 is a classic example which illustrates the need for effective Critical Condition Management. Both the process and power industries have wrestled with this need, but independently. 2003 Blackout: A Case for Critical Condition Management Keywords US Blackout, Critical Condition Management (CCM), NERC Summary CCM applications detect, monitor, and guide human operators through periods of abnormal operation. These applications have become more ac- cepted in process manufacturing, especially in the chemical and petrochemical industries. The properties of these abnormal periods have much in common with the details that have been reported thus far concern- ing the Eastern US blackout of August, 2003. Yet applications for dealing with abnormal situa- tions have been developed independently in the process and power industries and without much awareness in either camp of the related work done by others. Most major automation suppliers have partnered with application specialists to deliver CCM solutions. In the future, US power system operations, operating policies, and practices will become much more harmonized among geographic regions. This har- monization will include more advanced online condition diagnostic tools such as those developed for critical applications both in the process and power industries. 0 10 20 30 01530456075 Number of Abnormal Events vs. Minutes Before Blackout
  • 2. ARC Insights, Page 2 ©2003 • ARC • 3 Allied Drive • Dedham, MA 02026 USA • 781-471-1000 • ARCweb.com Analysis The North American Electric Reliability Council (NERC) sets the highest level operating policies for the US and Canadian electric grid. NERC is a policy-making organization, not an agency responsible for the implementa- tion of policy. Policies of NERC are embodied in their operating manual, which governs the content of policies and procedures developed by operating organizations. Thus NERC pol- icy is implemented by a wide variety of organizations that exercise the operating responsibility for parts of the North American electric grid. These same organizations contribute time and personnel to NERC for the devel- opment and refinement of NERC policy. The NERC Control Area Concept Operation of grid assets is performed by numerous op- erating entities. Each entity has responsibility for a particular subset of the grid, referred to as its “control area”. The control area may include all types of assets (Generation, Trans- mission, and Distribution) or only some types, such as Distribution components. The North American grid is the aggregate of all these control areas, plus the interconnections between various control areas, over which energy can be transferred. In the traditional model of a vertically in- tegrated electric utility, control areas were highly autonomous and largely responsi- ble for both the operations and the reliability of service in their own area. In- terconnections served merely to enhance the overall system stability and reliability. During the 1990s the US government man- dated open access to the transmission system and utility companies restructured toward organizations which would operate in emerging wholesale electric markets. NERC Transmission Policy NERC has as its highest operating policy goal the prevention of cascading outages such as occurred on August 14th 2003. The preamble to the NERC Supplier Product Name Emergin WirelessOffice Gensym Optegrity Honeywell @sset.MAX Matrikon ProcessGuard Nexus Oz OSIsoft PI System PAS AMOplus Software Products Used for CCM Control Area 1 Area Power Distribution Area Power Generation Area Transmission Components interconnection Control Area 2 interconnection Control Area 3 Control Area 1 Area Power Distribution Area Power Generation Area Transmission Components Control Area 1 Area Power DistributionArea Power DistributionArea Power Distribution Area Power GenerationArea Power Generation Area Transmission Components Area Transmission Components interconnection interconnection Control Area 2Control Area 2 interconnection interconnection Control Area 3Control Area 3 Conceptual View of an Electrical Control Area
  • 3. ARC Insights, Page 3 ©2003 • ARC • 3 Allied Drive • Dedham, MA 02026 USA • 781-471-1000 • ARCweb.com operating manual states: “All control areas shall operate so that instability, un- controlled separation, or cascading outages will not occur as a result of the most severe single contingency." The term “most severe single contingency” refers to any potential failure that causes a disturbance within the control area. Any such event, no mat- ter how serious, cannot be allowed to destabilize the control area. At any time if any single such event would destabilize a control region and/or its interconnections, then that control regions is no longer operating within “single contingency coverage”. It is the responsibility of regional system operators to manage their power system configuration so that these abnor- mal conditions are avoided. If their operations move outside this boundary, the NERC operating poli- cies specifies that they may remain in this state for a maximum of 30 min- utes. Furthermore the NERC policies regarding emergency operations dic- tate that a control area experiencing or anticipating an operating emergency shall communicate its status to neighboring systems. These commu- nications are to include notification of conditions such as the lack of single contingency coverage. Events of the August 2003 Blackout The complete sequence of events that occurred on August 14th 2003 is be- ing investigated in detail by numerous agencies. Nevertheless, key events leading up to the blackout have been detailed by NERC, AEP, and ITC (which owns and operates transmission assets in Michigan). Some of these event chronologies are listed on the websites of these organizations. The sequence of abnormal events began at about 2 PM with a trip of a 550 MW generating unit. The sequence of events then follows a classic pattern as the both the number and severity of abnormal events continue to build during the next two hours and 11 minutes (see the Figure on Page 1). Dur- ing that time system operators had to deal with the continuing degradation of the power transmission system they were charged with operating. Shortly before to 4:11 PM the abnormal events arrived in a virtual ava- t=0 t=30 Control area can withstand a first contingency event. Time in Minutes Operating Security Limit Violation Occurs Control area CANNOT withstand a first contingency event. Must be < 30 minutes. Control area can withstand a first contingency event. t=0 t=30 Control area can withstand a first contingency event. Control area can withstand a first contingency event. Time in Minutes Operating Security Limit Violation Occurs Control area CANNOT withstand a first contingency event. Must be < 30 minutes. Control area can withstand a first contingency event. Control area can withstand a first contingency event. The NERC Single Contingency Coverage Criterion
  • 4. ARC Insights, Page 4 ©2003 • ARC • 3 Allied Drive • Dedham, MA 02026 USA • 781-471-1000 • ARCweb.com lanche. Plotting the cumulative number of abnormal events versus their time to before the blackout began shows that operators were confronted with a continuously changing power system configuration during the entire evolution of the sequence. Only two periods between major abnormal events were longer than 15 minutes. Key Questions Remaining To Be Answered The international investigation of the blackout is likely to fork into two dis- tinct areas of study. The first and simpler task is to assemble and reconstruct the physical events that transpired, including the transient loads on various equipment and the reasons for equipment responses. This will be a matter of weeks, not months. The second, and far more difficult task, will analyze both the communications between control centers and the actual operator actions in terms of their conformance to written operating procedures. The task force must also determine if the existing procedures, had they been scrupulously followed, could have prevented the events which eventually transpired. The answers to these questions will lead to concrete recommendations concerning future policy changes, but that sec- ond task will take months, not weeks. The US Congress is not likely to wait that long before making up its own mind and taking some action of its own. Recommendations • Both CCM systems and procedures for emergency operation must be periodically tested to insure their feasibility and effectiveness. • Human factors in abnormal operation are as critical as automation func- tions. Please help us improve our deliverables to you – take our survey linked to this transmittal e-mail or at www.arcweb.com/myarc in the Client Area. For further information, contact your account manager or the author at hforbes@arcweb.com. Recommended circulation: All MAS-P and H clients. ARC Insights are published and copyrighted by ARC Advisory Group. The information is proprietary to ARC and no part of it may be reproduced without prior permission from ARC.