Transmission planning in Vermont Past, present and future Docket 7081 workshop By Dean LaForest...

Transmission planning in Vermont

Past, present and futureDocket 7081 workshop

By Dean LaForest

9/19/05

9/19/05 Docket 7081 Workshop Dean LaForest

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What is transmission planning? Transmission planning examines the need for

changes to the transmission network as load and power sources change through time in an area The transmission network consists of all electric

transmission lines and substations, typically built and constructed at 115,000 volts or above Vermont has an underlying subtransmission network with

significant facilities built and operated at 34,500 and 46,000 volts that often parallel the transmission network

VELCO owns and operates the transmission grid in Vermont, while the Vermont distribution companies own and operate the subtransmission network


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What tools and key sets of data are needed and necessary for transmission planning? Need software to model the behavior and performance

of the power system Need accurate model of the power system to capture

existing system performance and predict future system performance Model needs input on network characteristics (t-lines /

transformers), reactive power sources (generators / caps / sync condensers / FACTs devices), real power sources (generators / HVDC), and loads

Model needs sets of this data for each condition examined (load level / generation dispatch, etc.

Need a set of reliability standards against which to measure the system performance and determine whether reinforcements are needed


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What are VELCO’s sources for these sets of tools / data?

VELCO uses a widely utilized power flow analysis software, allowing high productivity and data interrogation capabilities

VELCO provides modeling information for the power system network to ISO-NE, who collects information from the rest of New England and the eastern US / Canada

VELCO gets load information from the distribution companies and the DPS for VT, and from the database provided by ISO-NE for areas outside of VT


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What are the regional reliability standards? NERC (North American Electric Reliability Council)

Standards found on NERC website (http://www.nerc.com/~filez/standards/Reliability_Standards.html#Transmission_Planning)

These are the minimum level of standards the system must meet

NPCC (Northeast Power Coordinating Council) Standards found on NPCC website (

http://www.npcc.org/criteria.asp) New England by way of the ISO-NE reliability standards is

and must be compliant with these criteria, which are more specific than NERC’s criteria


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What are the regional (NPCC) reliability standards?


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What are the New England (ISO-NE) reliability standards? ISO-NE’s planning criteria are located at

http://www.iso-ne.com/rules_proceds/isone_plan/index.html

Planning Procedure #3 is the key document


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Reliability Standards Evolve

NERC’s Standards will be more stringent, become mandatory, and will include penalties

The FERC will put in place an ERO – and Energy Reliability Organization


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The type of system under study matters Vermont system characteristics

Importer of electrical power Two large sources relative to the load Minimal reserves Winter and Summer peaking Sparse transmission network Located at one end of the New England system


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Planning design example . . . the problem Question – feed 50 MW of load (Addison county)

from a 50 MW generator (McNeil) 40 miles away Choices

46 kV line (can look like a distribution circuit) Single conductor Double conductor

115 kV line (standard VELCO h-frame) The issues

Provide adequate voltage for customers (within 5% of nominal)

Provide coverage for expected outages


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The first test . . . Can 46 kV work?


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The first test . . . Can 46 kV REALLY work?


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The first test . . . Can 46 kV work with two conductors (or bundled conductors)?


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40 miles . . .


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The second test . . . Can 115 kV work over 40 miles?


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To meet a N-1 design standard (be able to suffer the loss of one element) . . .


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VELCO’s design standard for transmission planning . . . Conforms to NERC, NPCC and ISO-NE planning

standards We consider the unavailability of system elements that

have potential long duration outages (more than one load cycle) Highgate DC converter Underground (or underwater) cables Transformers Generators

After system adjustment following first outage, VELCO tests all other potential outages


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What has VELCO done in the past for long range transmission planning VELCO’s recently performed long range studies

include the “Twenty Year Plan” (1987), the “Long Range Transmission Plan” (1992), and “A Strategic Planning Study” (2001) Each considered, and included, distribution company

projects / plans and current regional system information Each effort used the latest tools and system models

available The earlier two efforts included examination of power

source location and its influence on transmission expansion Each effort built on the past using better tools, and utilized

a more thorough understanding of the transmission network (with less predictable performance as time went on).


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What VELCO projects included analysis of future system

performance? Those projects included the Essex STATCOM (filed June 1999 – docket 6252), the Rutland Region Reliability Project (filed March 2001 – docket 6479), the Northern Loop Project (filed December 2002 – docket 6792) and the Northwest Reliability Project (filed June 2003 – docket 6860)


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What peak loads did VELCO experience during these planning efforts? Vermont seasonal peaks

550

600

650

700

750

800

850

900

950

1000

1050

1100

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

1980 to 2005

VT

lo

ad max sum

max win


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What will VELCO provide to comply with Act 61? VELCO will perform a study examining system performance 10

years from the present (i.e. 2015). The analysis will likely consider: All facilities available, and with one facility out due to a long term

outage Stressed transfer conditions The continued availability of energy from Highgate and how it

might influence transmission system design A reduced load growth scenario and how that might influence the

timing of transmission system reinforcements Proposed in-state generation projects and how they may

influence transmission system design VELCO will provide a draft report early in 2006 and hold public

meetings to promote discussion and elicit comments before publishing a final report by July 1, 2006


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What activities will take place within the Long Range Planning process? Involve the Vermont distribution companies (via the Vermont

Utility Planning Group) in review of interim results and proposed solutions Make certain that distribution utility issues / projects are

considered and properly reflected in the analysis Involve ISO-NE through collaborative meetings to review results,

refine modeling of beyond Vermont conditions / assumptions and provide / seek input on the transmission system design necessary to address system deficiencies that do not meet design criteria

Propose a series of alternatives to any discovered system wide deficiency Provide planning grade cost estimates for the alternatives to

allow ranking


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Questions?

9/19/05 Docket 7081 Workshop Lawrence Kirby

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A probabilistic reliability guideline for subtransmission planning, based on the

equal slope criterion


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costs

be

ne

fits

Conceptual Cost-Benefit Map

Diminishing returns on investment

B

C

Figure 1

A


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costs

be

ne

fits

Conceptual Cost-Benefit Map

"Most for Less" Planning Philosophy

To

tal b

en

efit

sim

ilar

to o

ption

C

Total cost similar to option A

A

B

C

Figure 2

desired tradeoff occurs near "knee" of curve


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Equal Slope Criterion

Transmission planning in Vermont Past, present and future Docket 7081 workshop By Dean LaForest...

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