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© 2002 F. Alvarado Slides to be available from http://www.pserc.wisc.edu Challenges in Power System Control Fernando Alvarado* Electrical and Computer Engineering University of Wisconsin-Madison (*) Vice-chair, IEEE-USA Energy Policy Committee Senior Consultant, Christensen Associates NSF/EPRI Workshop: Economics Electric Power and Adaptive Systems Arlington, VA, March 28, 2002 28 March 2002 Challenges in Power System Control PSERC How I got here Bruce: I want you to give a 30/45 minute talk on challenges in control of power systems Fernando: It is going to be difficult to prepare it Bruce: I want the big picture Fernando: Oh, the big picture is easy. I thought you wanted details 28 March 2002 Challenges in Power System Control “Everything that can be invented has been invented,” Charles H. Duell, commissioner, U.S. Patent Office, 1899 “Gee, power systems is an old area what are you going to do?” anonymous sources paraphrased, National Science Foundation, circa 2002 Themes of this talk Desirable power system attributes Interdependencies and complexity Challenge: Eliminate perception of complexity Market design challenges Can the system control the market? Can the market control the system? Control challenges Make the system fundamentally stable Make the system infinitely responsive Make the system heal itself 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Desirable system attributes It depends on who you ask! End users Investors/marketers Regulators/legislators Engineers/operators Economists Control engineers/researchers 28 March 2002 Challenges in Power System Control End user attributes Attribute Importance Free 5 Always there 4 Pollution free, invisible 3 Glitchless, perfect waveform 1 Exact frequency 1 28 March 2002 Challenges in Power System Control Investor/marketer attributes Attribute Importance 5 Profitable Understandable rules 2 Contractually feasible 1 28 March 2002 Challenges in Power System Control Regulator/legislator attributes Attribute Importance Cheap 5 Environmentally sound 4 Reliable 3 Fair to all 2 Simple 1 28 March 2002 Challenges in Power System Control Engineer/operator attributes Attribute Importance Reliable 5 Secure, robust 4 Flexible 3 Economic 2 Clean 1 28 March 2002 Challenges in Power System Control Economist attributes Attribute Importance Efficient 5 Efficient 5 Efficient 5 Fair 1 Simple 1 28 March 2002 Challenges in Power System Control Control viewpoint attributes Attribute Importance Stable 5 Robust, fault tolerant 4 Dispatchable 3 Nimble, flexible 2 Observable 1 28 March 2002 Challenges in Power System Control Complexity can make the system vulnerable The transmission system was designed area by area. Inter-area interconnections evolved in order to Perform economy exchanges Enable assistance during emergencies Design and operation presumes cooperation among grid participants Deregulation of the electric market leads to greater utilization of the grid 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Is complexity increasing? New patterns of grid utilization result in new flow and congestion patterns Less ability to control all aspects of the system introduces vulnerabilities “Humans in the loop” requires the development of intuition A larger interconnection is untested New problems may still arise Challenge: create the illusion of simplicity 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Impact of less centralization Less centralized planning can lead to “harder to control” systems No natural incentive to consider systemwide impact of individual actions Less centralized operation has pitfalls A complex system operating under stress requires coordination of actions Emergency actions may not be optimal under time and complexity pressures 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado What do markets do? Markets often align self-serving interests with society's interests Self-serving behavior can affect others adversely (even without market power) The grid magnifies adverse effects Action by one party to gain small additional profits can greatly increase cost to others “The gate of the transistor”, or can one MVAR really be worth that many MW? 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Some challenges Understanding stability when markets control significant aspects of the system The combination of economies of scale in supply and changing congestion patterns can lead to erratic and unstable system behavior Interactions among controls Flow control devices can affect flows in remote regions of a system Further understanding of voltage collapse Countermeasures to malicious actions Including failure mitigation and restoration 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Complexity reduction challenges • Study complexity-reduction technologies – Breakup the power grid by use of DC and/or FACTS technologies – Use dispersed technologies to mitigate the effect of failures – Build a grid that Wall Street can understand? • Methodologies for rapid understanding of a system under crisis conditions – The extremely large size of the grid has led to large computational challenges • Uncertainty and risk management tools for security management in the presence of large-scale system threats 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Additional control challenges Understand threats and failure modes that occur as a result of complexity Develop tools to mitigate the effects of complexity Mitigate the impact of complexity by ab-initio design Understand cascading failures 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Research on structural and policy implications on security Self interests can differ greatly from the common good Aligning the two by appropriate means can be difficult as a result of interdependencies complexities and vested interests A particular concern is market power Power system market power has unique features Beneficial actions to one party can affect another party adversely 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Additional questions Understanding impact of rules for markets, for ISOs and for end users Measure security taking into account uncertainties introduced by separate ownership of system assets Better understanding of conditions that hamper competition 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado It is the nature of markets to result in higher volatility. Volatility is not, in and of itself, bad! variability volatility Deregulated Location or time period 28 March 2002 Challenges in Power System Control cost cost Regulated variability volatility System 2 seam System 1 28 March 2002 Seams: spatial and temporal seam cost System 1 cost Deregulated: watch our for those seams Challenges in Power System Control cost System 2 cost Regulated: easier to control seams Concerns about interdependencies Dependency of the telecommunication and Web infrastructure on electric power Consider impact that energy conservation efforts can have on vulnerability Increased penetration of power electronic devices can have an undesirable effect on network security as a result of the removal of the "natural" voltage and frequency dependencies of loads Distributed generation can make systems less vulnerable 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Some specific activities Dynamic interaction between market and power system can induce instabilities Extended eigenanalysis including discrete effects We may have the first evidence of this in practice Interdependency of markets, policymaking and reliability can lead to system failure Unreliability: any involuntary curtailment of load Load as a resource 28 March 2002 Challenges in Power System Control © 2001 F. Alvarado Related challenge: funding Attract smart people to power engineering NSF funding crucial Higher salaries in industry key Intellectual and practical excitement important! New sensors, computing and communication create new control opportunities Foster new practical ideas, reject unrealistic ones Coordinate academic research with industrial experience Support quality research on a time scale of 10 years Many problems require years of study If academic power systems research continues to wither, the technological leadership will move further abroad 28 March 2002 Challenges in Power System Control Seven interesting examples of research in the control area “Thinking” 28 March 2002 Challenges in Power System Control Example #1: WAMS A global view of the status of the grid is essential Controls based in insufficient information are incapable of dealing with today’s complexities 28 March 2002 Challenges in Power System Control Example #2: Cascading outages Should we try to prevent them? Maybe they are inevitable! Work on self-organized criticality suggests this If so, would we not be better off by learning to cope with them? 28 March 2002 Challenges in Power System Control Example #3: Inherently stable controls Adding a new component to the system guarantees that the system if more stable than before the component is added Yes, they do exist One such control strategy was developed for FACTS devices by J. Gronquist Can we generalize this type of control? What do we give up? 28 March 2002 Challenges in Power System Control Example #4: Break up the grid? Would we be better off by splitting the grid into many Texas-sized grids connected solely by DC? Casazza, others have suggested it A phase shifter on every line??? Do phase shifters break up the grid? Really? How about even smaller grids? Micro-grids? 28 March 2002 Challenges in Power System Control Example #5: Congestion, properly managed, stabilizes the system! Idea has been shown by yours truly Others have dismissed this as crazy!!! Congestion is no good for economy Congested system is less efficient But congestion decouples and adds rigidity Mathematics: eigenvalue inclusion theory Is the converse also true? Will a larger single grid be LESS STABLE? YES. But we CAN make it work! 28 March 2002 Challenges in Power System Control Example #6: Control by price? And by price alone! Yes or no? YES! Shown by Glavitsch and yours truly But… Difficult to attain Linearity makes it difficult! (surprise here) Economies of scale make it hard Not everyone is “on their toes” 28 March 2002 Challenges in Power System Control Example #7: ________________ Fill in your pet idea not yet mentioned Box 28 March 2002 Challenges in Power System Control Grand Mini challenges Develop self-healing stable market-driven controls that adapt to changing conditions Provide effective control by market means alone to the extent possible Monitor and manage environmental externalities Develop new ways of delivering electricity Scratch that: develop new ways of meeting the user’s desire for electric energy in general Design controls with “humans in the loop” Make a single continental-sized grid work! Design for apparent simplicity! The bottom line: the needed work is multidisciplinary