trends in electrical transmission

8/4/2019 Trends in Electrical Transmission

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C. L. DeMarco, Transmission & Distribution Technology, Feb 2006 -C. L. DeMarco, Transmission & Distribution Technology, Feb 2006 -11 PSERC

Trends in Electrical Transmission

and Distribution Technology

Professor Chris DeMarco

Power Systems Engineering Research Center(PSERC)

Department of Electrical & Computer Engineering

University of Wisconsin-Madison, USA

[email protected]


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Main Points for Todays Talk

Self-Promotion: past & continuing role of UW-Madison

and other Universities in basic research that fed grid

technologies & developments.

Context: policy developments in the energy industry;

most recently, 2005 Energy Policy Act.

Hardware: highlight some technologies poised for wider

application power electronics & FACTS devices;

advanced conductor materials and superconductors;wide-area grid monitoring & visualization.


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Part I: Self-Promotion (of course)

UW-Madison has long history of achievement in

Electrical Power Systems education, outreach and

research. Much is coordinated through three groups:

(i) Power Systems Engineering Research

CenterPSERC;

www.pserc.wisc.edu

(ii) Wisconsin Electric Machines & Power

Electronics ConsortiumWEMPEC;

www.wempec.wisc.edu

(iii) Center for Power Electronic SystemsCPES

www.cpes.vt.edu


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What is PSERC?

In bureaucratic terms,PSERC is a National

Science Foundation Industrial/University

Collaborative Research Center.

In practical terms, it is a group of U.S.

universities sharing federal private funding to

conduct educational and research programs

in collaboration with industry members and

governmental agencies (e.g., DOE).


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What is PSERC?

PSERC Mission: engineer the future

electric power infrastructure by conducting research on challenges in providing

customers with reliable, economical, andenvironmentally-acceptable electric energy;

using collaboration among universities, industry, and

government;

informing policy-makers through research and

education;

educating the next generation of engineers.


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PSERC Collaborating Universities

Arizona State University- Gerald Heydt

University of California at Berkeley-Shmuel Oren

Carnegie Mellon University-Sarosh Talukdar

Colorado School of Mines- P.K. Sen

Cornell University-Robert J. Thomas

Georgia Institute of Technology

-Sakis Meliopoulos

Howard University- James Momoh

University of Illinois at Urbana-Peter Sauer

Iowa State University-Jim McCalley

Texas A&M University- Mladen Kezunovic

Washington State University-Anjan Bose

University of Wisconsin-Madison-Chris DeMarco

Wichita State University- Ward Jewell


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PSERC Industry MembersMidAmerican Energy Co

Midwest ISO

National Grid USA

National Rural Elec. Coop. Asn.

New York ISO

New York Power Authority

NxtPhase

Pacific Gas and Electric

PJM Interconnection

PowerWorld Corp.

RTE French TSO

Salt River Project

Siemens, EMA

Southern Company

Steel Tube Institute

TVA

Tri-State G&T

TXU Electric Delivery

U.S. DOE

Western Area Power Admin.

ABB

American Electric Power

American Transmission Co.

AREVA T&D

Arizona Public Service

Baltimore Gas & Electric

British Columbia Trans. Co.

California ISO

CenterPoint Energy

Duke Energy

Entergy

EPRI

Exelon

GE Energy

FirstEnergy

Institut de recherche dHydro-Qubec(IREQ)

ISO New England

Korea Elec. Power Res. Inst.

Michigan Electric Transmission Co.


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Selected PSERC Successes

Advanced power system visualization tools

(including commercialization of PowerWorld

software)

Institutional concept of testing power market

designs and policies before they are

implemented

Power system reliability Expertise for national grid reliability studies

Joint formation of the Consortium for Electric Reliability

Technology Solutions

Blackout of 2003 investigation and information resources


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PSERC Role in Consortium forElectric Technology Solutions

CERTS created in 1999 to research, develop, anddisseminate electric reliability technology solutions

Goal: to protect and enhance the reliability of the U.S. electricpower system under the emerging competitive electricitymarket structure

Funding: DOE EERE/Transmission Reliability program andCalifornia Energy Commission Public Interest EnergyResearch program

Performers: 4 National Labs (LBNL, ORNL, PNNL, SNL);PSERC; and Electric Power Group

PSERC provided researchers who participated in the DOENational Transmission Grid Study (2001/2), Power OutageStudy Team (1999/2000), advisors to 03 Blackout study


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Part II: Policy & Utility IndustryContext

To understand trends in transmission &distribution technologies, important tounderstand environment in which

technology investments may (or may not)occur.

Restructuring of U.S. power industrydramatically shook up responsibilities and

roles for who owned, planned for, andinvested in components of the grid.


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Policy & Utility Industry Context

Not surprisingly, uncertainty in who would own

and/or be responsible for what grid hardware

exacerbated long-standing downward trend in

U.S. grid infrastructure investment.

Following graph from E. Hirst, U.S.Transmission Capacity: Present Status andFuture Prospects, June 2004, has gotten wide

press www.electricity.doe.gov/documents/transmission_capacity.pdf


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Significant that this provocative graphs hard

data ends at 2000.

Trend it captures was very real, but growingevidence that trend is beginning to reverse

pretty dramatically.

Even preceding Energy Policy Act of 2005,

pretty strong evidence that U.S. transmission &distribution investment rebounding post-2000.


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Contributors to reversal of long decline in grid

technology investment:

August 2003 Eastern U.S. Blackout






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Perhaps proceeding slide oversimplifies slightly.

But it is no over-simplificiation to say 2003 Blackout

brought national focus to transmission grid technology &infrastructure, reflected in many parts of 2005 Energy

Policy Act (H.R. 6).

No legislation is ideal. But 2005 EPA makes effort to

facilitate new grid technology adoption throughmandatory reliability and interconnection standards, and

gives Federal Energy Regulatory Commission new

powers as backstop in transmission siting disputes.


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Part III: The Hardware (finally)

Power Electronics & Flexible AC Transmission

More quietly than information processingrevolution, advanced semi-conductors have

brought a parallel revolution in powerprocessing in silicon.

First hints of future came as semi-conductorthyristors to replaced mercury-arc values in highvoltage dc (HVDC) transmission (1967).


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The Hardware


But much of the advanced technology ready forgrid application today got its start as means to

provide flexible speed and torque control inelectric motors (beginning early 80s).

Much of the pioneering work carried out atUW-Madison, in previously mentionedWEMPEC consortium.


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The Hardware Advanced Grid

Technologies


One key new building-block technology is what

is known as the Voltage Source Converter

(VSC).

Roughly, the VSC a very versatile configuration

of high speed, low loss semiconductor switches,

able to convert power extracted from one

connection point in grid, and inject it at anotherpoint as a voltage source with fully

controllable magnitude & phase.


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The Hardware FACTS

Technologies

Why is a fully controllable voltagesource important? What need is being

addressed by these new technologies?

Key element of reliable transmission anddistribution operation is maintaining voltage tocustomer as close as possible to 60 Hzsinusoidal waveform at the rated magnitude

(e.g., at your wall outlet, you want 120 Voltsrms, with a clean, harmonic free waveform).


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The Hardware FACTS

Technologies

In the high voltage transmission grid, one big role forFACTS technologies is in reactive power supply andvoltage support.

Reactive power (Vars) is a much misunderstoodconcept in power engineering. It is an inherentconsequence of Teslas (rightful) victory over ThomasEdison the historic choice to build the worlds powergrid using sinusoidally varying voltages and currents.

To understand why we might want new FACTS devices,we have to understand a little about Vars.


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The Hardware FACTS

Technologies

So, what is this Reactive Power (Volt-Amperes-Reactive=Vars)? Just to confound the lawyers, weengineers also call this Imaginary Power.

WARNING: ELECTRICAL ENGINEERING LESSON TOFOLLOW!!! Ill try not to make it too painful.

Stay awake, and youll know soon enough aboutreactive power to confound the lawyers too.


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Background FACTS Technologies

for Reactive Power Support

Thanks to Mr. Tesla, voltages and currents shipped

down a transmission/distribution line are sinusoidally

varying with time, WITH ZERO AVERAGE VALUE!

(i.e., voltage & current oscillate back and forth, swinging

equally positive and negative, 60 times per second).

ButPOWER(=voltageXcurrent) shipped down a

transmission line, while also sinusoidally varying,

DOES NOT HAVE ZERO AVERAGE VALUE. Power

swings to large positive peak in the direction of delivery,

but can have smaller negative peakagainstdirection ofdelivery so 120 times per second, the load can send

some power back to the source!


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Typical Voltage & Current vs. time

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035-200

-150

-100

-50

0

50

100

150

200


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Superimpose graph of power vs.

time: note +/ swings

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035-400

-200

0

200

400

600

800

1000


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Power vs. time: more reactive

power, larger negative swing

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035-400

-200

0

200

400

600

800

1000


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The Hardware Advanced Grid

Technologies

As of last few years, technology vendors are

now poised to deliver a number of transmission-

level devices that offer very flexible control of

power, newest (and perhaps most promisingones) based on underlying VSC technology.

Following slides show some of these

technologies, and photos of installations.


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The Hardware FACTS

Technologies

Academics should avoid plugging any one

vendors hardware, but relatively small number

of players. Range of current technology on

market from Seimens, GE, Mitsubishi, ABB. Credits: FACTS hardware slides to follow

excerpted from Mike Bahrman, ABB,

presentation for NSF Workshop on Teaching for

Power Systems, Orlando FL, Feb. 05.

http://www.ece.umn.edu/groups/power/workshop_feb05/

Bahrman_Role_of_HVDC_&_FACTS.pdf


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The Hardware Advanced

Conductor Technologies

Challenge to transmission planning today is

often that of getting maximum benefit with

minimal footprint get the most out of existing

rights of way.

Therefore, Key Question: at high voltage

transmission level, what limits how much power

can be pushed down a line?


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Answer(s): a number of factors may place a

power or current limit on a line: thermal/sag,

steady state voltage problems, voltage stability

problems, or angular stability problems.

On shorter distance lines (very roughly - up to

150 miles), thermal issues/line sag often limiting

issue.


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Following scenario repeated too many timetimes in blackouts of 1996 and 2003: carry morecurrent on line line heats up due to I2R losses conductors expand line looses sufficient

clearance to trees/structures arcs overbreakers remove line from service remaining lines on system forced to carry morecurrent???

Low tech aside: doesnt help if utility had beeneconomizing on its vegetation control (treetrimming) budget.


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Possible higher tech solutions (without fullupgrade of voltage level or #of circuits): newconductor materials that stand more heat withless thermal expansion.

Again, a couple of vendors have currentproducts with these characteristics; I will unfairlyhighlight that one that makes pretty photosavailable on the web: 3M

www.3m.com/market/industrial/mcc/accr


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The Hardware Superconducting

Technologies

Return to some UW-Madison bolsterism - long

history of research effort in both high

temperature superconducting materials, and in

utility applications of superconducting magneticenergy storage.

(Truth in advertising some key breakthroughs

in practically processing & manufacturing

superconducting wire belong to buddies at MIT)


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Technologies

Again, relatively small number of players in thisfield. One of the key ones is company foundedby MIT folks, but whose power systemsexpertise is firmly housed in Wisconsin:

American Superconductor.

Keys to useful power systems applications arecoupling of practical high (in relative terms)temperature superconducting wire, with powerelectronics such as Voltage Source Inverter toget flexible delivery to distribution &transmission grid.


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Technologies

One proven application: tractor trailer sizedsuperconducting coils, with power electronics todeliver very fast acting, fully controllable reactivepower, and optionally some short term active

power.


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Technologies

Experience with installations here in WI includeDistributed Superconducting Magnetic EnergyStorage (D-SMES) systems in Rhinelander.

Entergy and several other utilities activelypromoting need for dynamic reactive supportto get maximum utilization of their transmissionsystem, including American Superconductorsreactive product, the D-VAR


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The Software Visualization,

Situational Awareness

Utilities have long recognized the need foraccurate real-time view of whats going on intheir distribution & transmission systems.Successful history of SCADA, state-estimation

and various control center functions in manyutilities.

But these systems broke down badly in 2003Blackout prompting blackout report to call forimproved situational awareness.


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Editorial comment: not clear that situationalawareness failure in 2003 was primarilytechnological (i.e. probably not fair to blame thesoftware designers if somebody forgets to turn it

back on after lunch).

But significant advances are taking place insoftware to make it easier to wade through hugemasses of data modern SCADA systems canprovide.


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Here I unapologetically hawk one vendorsproduct, as firms founder is my former graduatestudent, and PSERC researcher, Prof. TomOverbye.

Overbye and his coworkers createdPowerworld software package, with originalgoal of making power systems computationsmore easily understandable to policy makers.www.powerworld.com


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Powerworld is adapting advanced 3-D imaginingtechnologies that these days are driven bycomputer gaming community.

Bring these technologies and careful humanfactors studies to bear on putting information tooperators in quickly and intuitivelyunderstandable form.


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Examples include geographic profiles of voltagesupport throughout a system.


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The Hardware Situational

Awareness

Operators will need advanced tools, because the floodof useful data being measured and collected on thesystem grows.

Advent of very accurate, geographically distributed timesynchronization via GPS opened the doors years backto cost-effective phasor measurement units.

Remember those sinusoidal waveforms we nowcontinuously measure their relative phase in time, fromlocations 10s, 100s even 1000s of miles apart.


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The Hardware Situational

Awareness

Western U.S.s WSCC system has more than ten yearsof experience installing phasor measurement units,collectively termed Wide Area Measurement Systems

WAMS.

On-going project to get wide penetration in east: EasternInterconnect Phasor Project (EIPP).

But getting real value from all these measurements willdepend on creatively getting data to system operators ina meaningful form.


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Conclusions, in a nutshell

Lots of relatively new technology has reachedreasonable maturity over past decade, whileinvestments waited for resolution of policyuncertainties. These technologies are now

waiting in the wings to offer greater capability tomore fully utilize grid resources, whilemonitoring and maintaining reliability.

Last university pitch please dont forget to

keep priming the pump for students and newresearch to keep these advances coming infuture decades.

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