Reliability and Resiliency

51

What is Reliability?

Electricity delivered in the right amounts precisely when and where it is needed

– Three Components:• Power Supply• Transmission• Regional Coordination

Maintain area reliability, meet regulatory requirements, and support regional growth

TVA measures Reliability by:

– Load Not Served (LNS)

– Connection Point Interruptions (CPI)

We say we are reliable, but what does that really mean?

System reliability is maintained through continual work to repair/ replace/ upgrade

system elements

Reliability and Resiliency

52

KY

SC

AL

AR NC

GA

IL WV

TN

VAMO

MS

69 kV and below Lines

115, 138, 161 kV Lines

230, 345, 500 kV Lines

Hydro Plant

Combustion Turbine

Fossil Plant

Nuclear Plant

TVA Power Service Area

State BoundaryTVA Geographic Information & Engineering

TVA’s Integrated System

Reliability and Resiliency

53

TVA Transmission at a Glance

16,000+ circuit miles of line operated at 115-kV to 500-kV

500+ substations and switchyards (100-kV and above)

103,000+ transmission structures on 237,000 right-of-way acres

1,200+ customer connection points

2 fully-operational Control Centers

Reliability and Resiliency

54

TVA Generation Assets

Reliability and Resiliency

55

System Operations Center: Nerve center of TVA

24 x 7 operations

Real-Time monitoring of the TVA Transmission System

System Operations Center fully backed up by the Regional Operations Center

Critical systems can be executed independently

Continuous balancing of load and generation

System Operations: Keeping the Lights On

Reliability and Resiliency

56

TVA Reliability: Duration of Outages

For 14 years, the TVA system has been 99.999%

reliable

TVA’s current performance is within first quartile industry performance

99.999% reliability = 7.8 system minutes of Load Not Served (LNS)

Issues putting 99.999% at risk:

– Aging Assets

– Tightening Regulations

– Changing System Conditions

9.45

7.89

6.00

4.884.21

6.19

3.344.04

3.61 3.72

5.84

4.654.14 4.07 4.03

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

TVA’s Historical LNS

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TVA Reliability: Frequency of Outages

TVA’s current performance is within first quartile industry performance for Connection Point Interruption Frequency (CPIf)

Includes sustained and momentary interruptions

Top impacts to frequency of customer interruptions:

– Weather (Lightning and Wind)– Aging Assets– Foreign Objects (Birds, Animals, and Debris)

1.41 1.40

1.171.03

0.90 0.880.79 0.74 0.81 0.81 0.75

0.67 0.71 0.70 0.77

0

0.4

0.8

1.2

1.6

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Inte

rrup

tions

per

Con

nect

ion

Poin

t TVA’s Historical CPIf

Since 2004*, TVA has been a Top Quartile performer or better

*2004 was the first year of an Industry Benchmarking being available with all voltage

classes

Reliability and Resiliency

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TVA Reliability: Consistency of Voltage

110000

120000

130000

140000

150000

160000

0 0.05 0.10 0.15

Tranmission Voltage Sag

Electrotek/EPRI PQView®

Vol

tage

(V

)

Time (s)

Vab

Voltage sags can shut down sensitive production systems

– Downtime costs for 50MW sensitive industry >$100k in production losses

TVA’s PQ Program goal is reducing voltage sags associated with transmission system faults

Program targeted at top 100 largest industries in the Valley:

Food Production Textiles Paper Printing Chemicals Rubber

Power Quality program is focused on keeping the industry in the TN

Valley running smoothly

Plastics Glass Primary Metals Electronics Transportation

Reliability and Resiliency

Transmission Voltage Sag

59

TVA Reliability: Matching Generation to Load

Reliability and Resiliency

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Transmission: Connecting Generation to Load

Real-Time balancing of generation (supply) and load (demand)

– Generation includes native sources and purchases

– Diverse plant types ramp at different rates

– Changing generation mix can significantly impact ability to meet load requirements

Sufficient Reserves must be maintained at all times to recover from unexpected large generation losses

61

Planning for System Resiliency

Generation decisions cannot be made without Transmission support

– Projects must be in place to ensure power can still be delivered where needed

Robust Transmission system is needed to provide flexibility and respond to system events

– Localized storm damage does not impact the entire system

– Single generator loss can be balanced with power from another source

KY

SC

AL

AR NC

GA

IL WV

TN

VAMO

MS

69 kV and below Lines

115, 138, 161 kV Lines

230, 345, 500 kV Lines

Hydro Plant

Combustion Turbine

Fossil Plant

Nuclear Plant

TVA Power Service Area

State BoundaryTVA Geographic Information & Engineering

Reliability and Resiliency

62

Big Picture Reliability: Eastern Interconnection

TVA is one of 23 Planning Authorities in the Eastern Interconnection

TVA has 68 interconnections with 12 neighboring systems

Partner with other industry participants to,

– Prevent cascade of instabilities across neighboring systems (NE Blackout)

– Plan robust and flexible systems

– Guarantee resource adequacy

TVA partners with others to ensure the reliability of the Eastern Interconnection

and the U.S.

Reliability and Resiliency