28 March 2002Challenges in Power System Control Fernando Alvarado* Electrical and Computer...

28 March 2002 Challenges in Power System Control

Challenges in Power System ControlChallenges in Power System Control

Fernando Alvarado*Electrical and Computer Engineering

University of Wisconsin-Madison

PSERC

NSF/EPRI Workshop: EconomicsElectric Power and Adaptive SystemsArlington, VA, March 28, 2002

(*) Vice-chair, IEEE-USA Energy Policy CommitteeSenior Consultant, Christensen Associates

Slides to be available from http://www.pserc.wisc.edu© 2002 F. Alvarado


How I got hereHow 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

“Gee, power systems is an old areawhat are you going to do?”

anonymous sources paraphrased, National Science Foundation, circa 2002

“Everything that can be inventedhas been invented,” Charles H. Duell, commissioner, U.S. Patent Office, 1899


Themes of this talkThemes of this talk

Desirable power system attributes

Interdependencies and complexityChallenge: Eliminate perception of complexity

Market design challengesCan the system control the market?

Can the market control the system?

Control challengesMake the system fundamentally stable

Make the system infinitely responsive

Make the system heal itself

© 2001 F. Alvarado


Desirable system attributesDesirable system attributes

It depends on who you ask!End users

Investors/marketers

Regulators/legislators

Engineers/operators

Economists

Control engineers/researchers


End user attributesEnd user attributes

Attribute Importance

5

Always there 4

Pollution free, invisible 3

Glitchless, perfect waveform 1

Exact frequency 1

Free


Investor/marketer attributesInvestor/marketer attributes


5

Understandable rules 2

Contractually feasible 1

Profitable


Regulator/legislator attributesRegulator/legislator attributes


5

4

3

2

1

Cheap

Environmentally sound

Reliable

Fair to all

Simple


Engineer/operator attributesEngineer/operator attributes


5

4

Flexible 3

Economic 2

Clean 1

Reliable

Secure, robust


Economist attributesEconomist attributes


5

5

5

Fair 1

Simple 1

Efficient

Efficient

Efficient


Control viewpoint attributesControl viewpoint attributes


5

Robust, fault tolerant 4

Dispatchable 3

Nimble, flexible 2

Observable 1

Stable


Complexity can make the Complexity can make the system vulnerablesystem 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

© 2001 F. Alvarado


Is complexity increasing?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 untestedNew problems may still arise

© 2001 F. Alvarado

Challenge: create the illusion of simplicity


Impact of less centralizationImpact of less centralization

Less centralized planningplanning can lead to “harder to control” systems

No naturalnatural incentive to consider system-wide impact of individual actions

Less centralized operationoperation has pitfallsA complex system operating under stress

requires coordination of actions

Emergency actions may not be optimal under time and complexity pressures

© 2001 F. Alvarado


What do markets do?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 effectsAction by one party to gain small

additional profits can greatly increase cost to others

© 2001 F. Alvarado

“The gate of the transistor”, orcan one MVAR really be worth that many MW?


Some challengesSome 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 systemsystem behavior

Interactions among controlsFlow control devices can affect flows in remote

regions of a system

Further understanding of voltage collapse

Countermeasures to malicious actionsIncluding failure mitigation and restoration

© 2001 F. Alvarado


Complexity reduction Complexity reduction challengeschallenges

• 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

© 2001 F. Alvarado


Additional control challengesAdditional 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

© 2001 F. Alvarado


Research on structural and Research on structural and policy implications on securitypolicy 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 powerPower system market power has unique

features

Beneficial actions to one party can affect another party adversely

© 2001 F. Alvarado


Additional questionsAdditional 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

© 2001 F. Alvarado


Regulated cost

variabilityvolatility

Deregulated cost

variabilityvolatility

It is the nature of markets to resultin higher volatility.

Volatility is not, in and of itself, bad!

Location or time period


System 1 cost

System 2

cost

seam

System 1

cost

System 2

cost

seam

Regulated: easier to control seams Deregulated: watch

our for those seams

Seams:spatial

andtemporal


Concerns about Concerns about interdependenciesinterdependencies

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 effectundesirable 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

© 2001 F. Alvarado


Some specific activitiesSome 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

© 2001 F. Alvarado


Related challenge: fundingRelated challenge: funding

Attract smart people to power engineeringNSF funding crucialHigher salaries in industry keyIntellectual and practical excitement important!

New sensors, computing and communication create new control opportunities

Foster new practical ideas, reject unrealistic onesCoordinate academic research with industrial experience

Support quality research on a time scale of 10 yearsMany problems require years of studyIf academic power systems research continues to wither,

the technological leadership will move further abroad


Seven interesting examples of Seven interesting examples of research in the control arearesearch in the control area

“Thinking”


Example #1: WAMSExample #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


Example #2: Cascading outagesExample #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?


Example #3: Inherently stable Example #3: Inherently stable controlscontrols

Adding a new component to the system guarantees that the system if more stable than before the component is added

Yes, they do existOne such control strategy was

developed for FACTS devices by J. Gronquist

Can we generalize this type of control?

What do we give up?


Example #4: Break up the grid?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?


Example #5: Congestion, properly Example #5: Congestion, properly managed, stabilizes the system!managed, stabilizes the system!

Idea has been shown by yours trulyOthers have dismissed this as crazy!!!

Congestion is no good for economyCongested system is less efficient

But congestion decouples and adds rigidityMathematics: eigenvalue inclusion

theoryIs the converse also true?Will a larger single grid be LESS STABLE?

YES. But we CAN make it work!


Example #6: Control by price?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”


Example #7: ________________Example #7: ________________

Fill in your pet idea not yet mentioned

Box

Grand Mini challengesGrand Mini challenges

Develop self-healing stable market-drivenmarket-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 electricityScratch 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

28 March 2002Challenges in Power System Control Fernando Alvarado* Electrical and Computer...

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