1

NWPUD Transmission Reinforcement

Planning

EE 456

Project 2 Final Report May 18th, 2015

Prepared by:

Yussuf Roble Bayu Halim Ki Hei Chan

2

Table of Contents Executive Summary ...................................................................................................................................... 3

Load Growth ................................................................................................................................................. 4

Design Consideration .................................................................................................................................... 5

1st design .................................................................................................................................................. 5

2nd design................................................................................................................................................... 8

Technical Feasibility ............................................................................................................................... 10

Line Reactance Calculation .......................................................................................................................... 5

Load Growth only System Upgrade............................................................................................................ 10

Wind Farm only System Upgrade ............................................................................................................... 11

Cost Allocation ........................................................................................................................................... 12

Standards ..................................................................................................................................................... 13

Impact of Global Warming on our Design ..................................................... Error! Bookmark not defined.

Conclusion .................................................................................................................................................. 13

Reference .................................................................................................................................................... 13

Appendix ..................................................................................................................................................... 14

3

Executive Summary

Figure 1

Recommended system upgrade

After analyzing different design options, we have decided to upgrade the system according to the

design shown in Figure 1. This design has a total construction cost of $37,230,142 with a total

annualized cost of $1,657,206/year. In comparison with other design upgrade options that we have

considered (different designs will be further analyzed in the later sections), this design is the

cheapest to build.

One of the most important factors in choosing the cheapest design in this project is minimizing the

number of poles and insulators that need to be rebuilt. The upgrade cost of any designs in this

project is highly dependent on the number of new poles and insulators that need to be installed

because the cost of poles and insulators are much more expensive compared to other equipment.

In our 1st design, the cost of poles and insulators is $25,520,000 while in our 2nd design, the cost

of poles and insulators is $32,870,000. Looking at just the cost of just poles and insulators, the 1st

design is much cheaper than the 2nd design. Therefore, the 1st design upgrade is the best alternative.

4

Load Growth

Figure 2

Load growth with linear trend

Figure 3

Load growth with logarithmic trend

We predicted the load growth in seven years using two different trends: linear and logarithmic

(Figure 2 and Figure 3 respectively). The R2 value, which represents how close the date points

are to the trend line, of the linear trend is slightly higher than the R2 value of the logarithmic

trend. Therefore, the linear trend is slightly more accurate, and we predicted the load growth in

seven years to be approximately 338 MW.

220 224 222 235 234 248 258 263 275 275 283 291

y = 6.9231x - 13660R² = 0.9746

0

50

100

150

200

250

300

350

2002 2004 2006 2008 2010 2012 2014 2016

Pe

ak L

oad

(M

W)

Year

Peak Load growth (linear)

220 224 222 235 234 248 258 263 275 275 283 291

y = 13911ln(x) - 105552R² = 0.9745

0

50

100

150

200

250

300

350

2002 2004 2006 2008 2010 2012 2014 2016

Pe

ak L

oad

(M

W)

Year

Peak load growth (logarithmic)

5

Line Reactance Calculation According to NESCode 233 regarding clearances between wires that ensure live-line worker safety,

115 kV conductors require 6 feet of spacing between a conductor and an insulator, which translates

to 12 feet spacing between conductors. Assuming spacing between conductors is a linear function

of voltage, a 69 kV conductors require approximately 6 feet of spacing.

7

312 23 31

2*10 ln( ) H/ m

where

,

eq

s

eq

xy

s

DL

D

D D D D

D spacing betweenconductors

x y

D GMR of conductor

Equation 1

Line reactance formula [1]

Equation 1 above is used to determine the reactance of a conductor. The inductance value, L, gets

multiplied by the length of the conductor (in m). This represents the line inductance. This value

gets further multiplied by 2π*frequency to determine the line reactance.

Design Consideration

1st design

Our 1st design connects the Mustang Wind Farm to bus 4. Bus 4 is located in a 115 kV transmission area

and also it’s close to major load centers. On top of that, the 115 kV transmission line conductors

have higher rating which enables them to handle the load growth and the addition of the wind farm.

Furthermore, bus 4 is the only bus that requires the least right of way compared to all other 115

kV buses. Alternatively, we could have connected to bus 28 which is closer to wind farm in terms

of right of way, but it overloads all lines in the 69 kV area.

As mentioned earlier, through the design priority and constraint analysis our group found it’s

beneficial to connect the Mustang Wind Farm to bus 4. We based our analysis on factors like

minimum right of way, generator outage, testing for four different cases, conductor upgrade, be

able to reuse poles and insulators, proximity to major load centers and we concluded that

connecting the Mustang Wind Farm to bus 4 will have the minimum cost compared to all the other

available options.

Even though this design calls for 8 circuit breakers, 2 transformers, 11 miles 50 foot right of way,

64.5 miles of conductors upgrade, 43 miles of new conductors, and 1179 new poles and insulators

it will roughly cost $7M less than Design 2. If cost is the primary deciding factor for NWPUD,

then this design is the best and our team highly recommends it.

Figure 4 below shows the system diagram from PowerViz. The two parallel red conductors on the

left side of the figure 1 are from the wind farm while the other two red lines are two new conductors

6

added to the system. The orange lines call for an upgrade of conductors, poles, and insulators

whereas the blue lines requires conductor upgrade but it will reuse the original poles and insulators.

Figure 4

1st design system diagram

Figure 5

1st design system upgrade

7

Line number

From Bus to

Bus Poles and insulator

Size

( Kcmils)

Length of conductor

(miles)

Line 6 2 to 5 single, 115 KV 636 20

Line 7 2 to 6 no replacement needed 266.8 20

Line 8 4 to 6 Double, 115 kV

397.5 10.5

New Line 4 to 6 336.4 10.5

Line 9 5 to 7 single, 115 KV 795 3.2

Line 10 7 to 6 single, 115 KV 874.5 2.88

Line 11 6 to 8 Double, 115 KV 4/0.

11.2

New Line 6 to 8 11.2

From wind farm WF to bus 4 Double, 115 KV 477 11

Table 1

Line reinforcement on 1st design

Figure 5 and Table 1 highlight the upgrade that is required for the 1st design. This design requires

upgrade of 64.5 miles of conductors and addition of 43 miles of new conductors. It also calls for

updating all the poles and insulators that their conductor is upgraded except line 7 where the new

conductor weight is not 30% more than the original conductor weight. There is an addition of two

new lines for the Wind farm and also two new lines to reroute power to another bus. Figure 5 and

Table 1 are color coded to show conductors’ sizes, conductor’s length, and poles and insulators

replacement on a particular line.

Table 2

1st design cost summary

Design one alternative is substantially less expensive than design 2 alternative. This is due to the

cost of right of way and the number of lines requiring conductor upgrade which also effects how

many poles and insulators that have to be purchased. On top of that, a transformer and 2 other lines

Item quantity Capital Cost ($) Anualized Cost ($)

Right of Way 11 miles, 50 foot $2,667,500 $115,402

Conductor 107.5 miles $2,898,642 $125,402

Circuit Breakers 8 $144,000 $6,229.80

Transformers 2 $6,000,000 $306,116

Poles and Insulators 994 $25,520,000 $1,104,056

TOTAL COST $37,230,142 $1,657,206

TOTAL COST

8

were overloading before adding a line between bus 4 to bus 6 and this significantly reduced the

cost of design one.

Note: Voltage profiles of different scenarios of the 1st design can be found in the appendix (Figure

9-Figure 12) and the cost breakdown of the 1st design can also be found in the appendix (Table 8-

Table 11).

2nd design

Our second design use three transmission conductor lines connected the Mustang Wind Farm. A

parallel lines connected to bus14 and a line connected to bus 27. Although using three conductors

need more material costs and right of way cost, we found this design can reduce too many lines

overload. Also, bus 14 and bus 27 is relatively close to the Wind Farm, and they both are 69KV.

Therefore, we try this design and use it for comparison.

In order to bear the load growth, N-0 and N-1 contingency stability study, we decided to add some

parallel conductor lines with parts of original lines which can decrease their total impedance and

reduce too much current flowing to the other parts and cause overvoltage.

Figure 6

2nd design system upgrade

9

Line number

From Bus to

Bus

Poles and

insulator

Size

( Kcmils)

Length of conductor

(miles)

Line 6 2 to 5 single, 115 KV 477 20

Line 8 4 to 6 single, 115 KV 266.8 10.5

Line 11 6 to 8 double, 115 kV

397.5 11.2

New Line 6 to 8 397.5 11.2

Line 15 12 to 14 Single, 115 KV 266.8 6.4

Line 18 14 to 15 single, 115 KV 266.8 3.5

From wind

farm WF to bus 14 Double, 69 KV 666.6

7.6

From wind

farm WF to bus 14

7.6

From wind

farm WF to bus 27 Single, 69 KV

336.4

12.4

Table 3

Line reinforcement on 2nd design

Figure 6 above shows where the nine lines are added and Table 3 indicates the details of these

lines we choose. Figure 6 and Table 3 are color coded to show conductors’ sizes, conductor’s

length, and poles and insulators replacement on a particular line.

Material Capital Cost Annualized Cost

Total cost for 3-phase conductor $ 1,973,712 $ 85,387

Total cost for transformer $ 6,000,000 $ 306,116

Total cost for eight circuit breaker $ 132,000 $ 5,711

Price of poles $ 32,870,000 $ 1,422,034

Right of Way $ 2,910,000 $ 125,894

Total Cost $43,885,712 $1,889,587 Table 4

2nd design cost summary

This alternative requires a little bit more materials for constructions. In addition to the cost of

conductors, we need: 20 miles, 30 feet right of way, six 69kV circuit breakers, two 115kV circuit

breaker, and two 60MVA step up transformer on the wind farm.

Note: Voltage profiles of different scenarios of the 1st design can be found in the appendix (Figure

13-Figure 16) and the cost breakdown of the 1st design can also be found in the appendix (Table

12-Table 15)

10

Technical Feasibility

The 1st design requires the acquisition of 11 miles of right-of-way, and must cross 2 buses and

three transmission lines depending on final line routing. Our team has also increased the cost

allocation of poles in order to accommodate the larger poles necessary for an 115kV line to cross

above a 69kV line between bus 15 and bus 12. There are significant overloads on the conductors

close to bus 4 due to the addition of the wind farm and load growth, this entire design must be

implemented by 2017.

Load Growth only System Upgrade

Figure 7

Load growth only system upgrade

11

Line number From Bus to Bus Poles and insulator Size (kcmils) Length of conductor(miles)

Line 6 2 to 5 single, 115 KV 397.5 20

Line 7 2 to 6 no replacement needed 300 20

Line 8 4 to 6 no replacement needed 397.5 10.5

Line 9 5 to 7 single, 115 KV 477 3.2

Line 10 6 to 7 no replacement needed 397.5 2.88

Line 11 6 to 8 single, 115 KV 300 11.2

Line 38 8 to 28 single, 115 KV 336.4 20.8

Line 39 6 to 28 single, 115 KV 266.8 20.8

Table 5

Line reinforcement on load growth only system upgrade

The total cost for load growth only system upgrade is $28,539,248 with an annualized cost of

$1,234,675. The upgrade includes replacing some of the poles and insulators and reinforcing

conductors. Figure 7 and Table 5 show the lines that require reinforcement and poles and insulators

that need to replace with its corresponding length and distances. Figure 7 and Table 5 are color

coded to show conductors’ sizes, conductor’s length, and poles and insulators replacement on a

particular line.

Wind Farm only System Upgrade

Figure 8

Wind farm only system upgrade

12

Line number From Bus to Bus Poles and insulator Size (kcmils) Length of conductor(miles

Line 6 2 to 5 single, 115 kV 605 20

Line 7 2 to 6 no replacement needed 300 20

Line 9 5 to 7 single, 115 kV 605 3.2

Line 10 6 to 7 single, 115 kV 795 2.88

Line 11 6 to 8 single, 115 kV 300 11.2

Line 31 24 to 25 no replacement needed 226.8 1.6

Line 38 8 to 28 single, 115 kV 266.8 20.8

From wind farm WF to bus 4 double, 115 kV 500 11

Table 6

Line changes on wind farm only system upgrade

The total cost for load growth only system upgrade is $36,213,875 with an annualized cost of

$1,563,210. The upgrade includes replacing some of the poles and insulators, reinforcing

conductors, and installing new lines to provide connection from the wind farm to bus 4. Figure 8

and Table 6 show the lines that require reinforcement and poles and insulators that need to replace

with its corresponding length and distances. Figure 8 and Table 6 are also color coded to show

conductors’ sizes, conductor’s length, and poles and insulators replacement on a particular line.

The wind farm only system upgrade requires an 11 miles, 50 feet right of way which costs

approximately $2,667,500. In addition, four 115 kV circuit breakers and two 60 MVA step up

transformer need to be purchased to complete the connection from the wind farm to bus 4.

Cost Allocation The cost allocation between the wind farm and the rate payers is governed by Equation 2 below.

wind farm only

windfarm combined

wind farm only load growth only

ratepayers combined windfarm

CC C

C C

C C C

Equation 2

cost allocation formula

13

Using the above formula, the cost allocation is determined as such

1st design wind farm pays $20,821,534 (55.9%)

rate payers pay $16,408,788 (44.1%)

2nd design wind farm pays $24,543,553 (55.9%)

rate payers pay $19,342,159 (44.1%) Table 7

cost allocation summary

Standards

Conclusion

Reference [1]J. Glover, M. Sarma and T. Overbye, Power system analysis and design, 5th ed. Stamford: Cengage

Learning, 2010.

14

Appendix

Figure 9

1st design n-1 contingency results during full load, full wind

Figure 10

1st design n-1 contingency results during light load, full wind

15

Figure 11

1st design n-1 contingency results during light load, light wind

Figure 12

1st design n-1 contingency results during full load, light wind

16

Table 8

1st design conductor cost breakdown

Table 9

1st design right of way cost

Table 10

1st design Poles and insulators cost breakdown

Item Quantity Voltage/MVA Bus Cost ($)

Circuit breaker 4 115 kV WF to bus 4 $72,000

Circuit breaker 2 115 kV Bus 4 to 6 $36,000

Circuit breaker 2 115 kV Bus 6 to 8 $36,000

Transformer 1 60 MVA WF to bus 4 3000000

Transformer 1 60 MVA WF to bus 4 3000000

Total cost $6,144,000 Table 11

1st design equipment cost breakdown

Line # From bus to bus New Cond. Size (Kcmils) Distance (miles) lbs/Mile Tot lbs of Cond.

Line 6 bus 2 bus 5 874.5 19 5940 112860

Line 7 bus 2 bus 6 300 19 2178 41382

Line 8 bus 4 bus 6 636 10.5 5213 54736.5

Line 9 bus 5 bus 7 900 3 6112 18336

Line 10 bus 7 bus 6 900 2.5 6112 15280

Line 11 bus 6 bus 8 636 10.5 5213 54736.5

WF WF bus 4 477 11 3462 38082

WF WF bus 4 477 11 3462 38082

NL46 bus 4 bus 6 397.5 10.5 2885 30292.5

NL68 bus 6 bus 8 336.4 10.5 2442 25641

Total cond. in lbs 429428.5

3 phase cond. lbs 1288285.5

Cost of cond. in $ $2,898,642.38

Line number From bus To bus Line voltage Distance (miles) Cost ($)

WF Lines WF 4 115 KV 11 $2,667,500

Right of way

Lines Single or double Distance in feet Span in (ft) # of poles Cost ($)

Line 6 Single, 115 KV 100320 300 334.4 6688000

Line 8 Double, 115 KV 55440 300 184.8 5544000

Line 9 Single, 115 KV 15840 300 52.8 1056000

Line 10 Single, 115 KV 13200 300 44 880000

Line 11 Double, 115 KV 55440 300 184.8 5544000

From WF to Bus 4 Double, 115 KV 58080 300 193.6 5808000

Total cost $25,520,000

POLES AND INSULTORS

17

Figure 13 2nd design n-1 contingency results during full load, full wind

Figure 14 2nd design n-1 contingency results during light load, full wind

18

Figure 15 2nd design n-1 contingency results during light load, light wind

Figure 16 2nd design n-1 contingency results during full load, light wind

19

Line number From Bus to Bus Distance (miles) Size ( kcmils) Total pounds

6 2 to 5 20.9 477 86187

8 4 to 6 9.8 266.8 17692

11 6 to 8 10.9 397.5 71498

New line 6 to 8 10.9 397.5

15 12 to 14 6.4 266.8 11467

18 14 to 15 3.45 266.8 6225

0 WF to bus 14 7.6 666.6 6914

43 WF to bus 14 7.6 666.6

44 WF to bus 27 12.4 336.4 30192

Total cond. In lbs 230175

3 phase cond. In lbs 690525

Total cost of cond. $1,973,712 Table 12

2nd design conductor cost breakdown

Line number From Bus to Bus Distance (miles) Feet Cost

0, 43 WF to bus 14 7.6 30 $ 1,105,800

44 WF to bus 27 12.4 30 $ 1,804,200 Table 13

2nd design right of way cost

Line number From Bus to Bus Distance (miles) Voltage (KV) # poles Cost

45 2 to 5 20.9 115 368 (double) $ 11040K

49 4 to 6 9.8 115 173 (double) $5190K

46 6 to 8 10.9 115 192 (double) $5760K

50 6 to 8 10.9 115

47 12 to 14 6.4 69 112 (double) $2688K

48 14 to 15 3.45 69 61 (double) $1464K

0 WF to bus 14 7.6 69 135 (double) $3240K

43 WF to bus 14 7.6 69

44 WF to bus 27 12.4 69 218 $3488K

Total cost $32,870,000 Table 14

2nd design cost poles and insulators cost breakdown

Item Quantity Voltage(MVA) Bus Cost

Circuit Breaker 6 69KV WF to 14

WF to 27

$ 96,000

Circuit Breaker 2 115KV Bus 6 to 8 $ 36,000

Transformer 2 60MVA WF to14

WF to 27

$ 6,000,000

Total cost $6,132,000 Table 15

2nd design equipment cost breakdown

20

Figure 17

Load growth only power flow results during normal condition

Figure 18

Load growth only n-1 contingency results during normal condition

21

Figure 19

Load growth only power flow results during light load

Figure 20

Load growth only n-1 contingency results during light load

22

Figure 21

Load growth only power flow results when Claytor is out

Figure 22

Load growth only n-1 contingency results when Claytor is out

23

Figure 23

Load growth only power flow results when one of the generating units in Glenlyn is out

Figure 24

Load growth only n-1 contingency results when one of the generating units in Glenlyn is out

24

Figure 25

Wind farm only power flow results during normal condition

Figure 26

Wind farm only n-1 contingency results during normal condition

25

Figure 27

Wind farm only power flow results during light load, full wind

Figure 28

Wind farm only n-1 contingency results during light load, full wind

26

Figure 29

Wind farm only power flow results during full load, light wind

Figure 30

Wind farm only n-1 contingency results during full load, light wind

27

Figure 31

Wind farm only power flow results when Claytor is out (assuming full wind)

Figure 32

Wind farm only n-1 contingency results when Claytor is out (assuming full wind)

28

Figure 33

Wind farm only power flow results when one of the generating units in Glenlyn is out (assuming full wind)

Figure 34

Wind farm only n-1 contingency results when one of the generating units in Glenlyn is out (assuming full wind)