EE 456 Project:
Electric System Planning
Team Members:
Abrahem Al-afandi
Majed Al-ataishi
Thyab Al-hajeri
12-13-2013
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Table of Contents
Executive Summary …………………………………………………………………………………..…3
1. Base Case I (2013) ……………………………………………………………………………….…..4
1.1 Transformers …………………………………………………………………………………..……………………....4
1.2 Transmission Lines ………………………………………………………………………………………………….4
1.3 Generators …………………………………………………………………………………………………..…………..5
1.4 Violations of base case ……………………………………………………………………………..………………6
1.5 Power flow simulation of Base case 1 (2013) …………………………………………………………..7
2. Base Case II (2030) …...………………………………………………………………………………………………..7
2.1 Load Growth …………………………………………………………………………………………...………………..7
2.2 Total Generation Needed ……………………………………………………………………………………..…..7
2.3 Capacity Credit ………………………………………………………………………………………………………....8
2.3 Adding 2 transmission lines ……………………………………………………………………………….........9
2.4 Power Flow Simulation for Base Case II (2030) ……………………………………………………..…9-10
3. N-1 Contingency …………………………………………………………………………………….……………………11
3.1 N-1 contingency for 10% wind ……………………………………………………………………………..….11
3.1.1 Simulation of 10% wind ……………………………………………………………………………..…………11
3.1.2 Transmission lines …………………………………………………………………………………………..……11-12
3.1.3 Transformers ……………………………………………………………………………………………..…………12-13
3.1.4 Generators ……………………………………………………………………………………………………………13
3.2 N-1 contingency for 90% wind …………………………………………………………………………………14
3.2.1 Simulation of 90% wind …………………………………………………………………………..……………14
3.2.2 Transmission lines .…………………………………………………………………………..…………………..14-15
3.2.3 Transformers ………………………………………………………………………………………………………..15
3.2.4 Generators ……………………………………………………………………………………………………………16
4. Solution …………………………………………………………………………………………………………………………16
4.1 90% Wind Solution …………………………………………………………………………………………………16-17
4.2 10% Wind Solution …………………………………………………………….…………………………………..17
4.3 Diagram of the System after the Solution ……………………………………………………………..…17-18
5. Selling power to a costumer at bus 1 …………………………………….……………………………..19
6. Economic Analysis …………………………………………………………………………………..………………..20
6.1 Transmission Lines Cost ……………………………………………………………………………….………..20
6.2 Substations Cost ……………………………………………………………………………..………………………21
6.3 Circuit Breaker Cost ……………………………………………………………………………………………….21
6.4 Transformer cost …………………………………………………………………………….……………………..21
6.5 Capacitors cost …………………………………………………………………………………………….…………21
6.6 Natural gas cost ……………………………………………………………………………………………..……….22
6.7 Wind cost ………………………………………………………………………………………………….……………22
6.8 The Overall cost of the system ……………………………………………………………………..…………22
7. Conclusion ………………………………………………………………………………………………………………….22
References …………………………………………………………………………………………………….………………..23
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Executive Summary
Our electric system consisted of 17 buses, 3 of these buses are generator buses, and
bus 1 “OWL” is the swing bus. The system also had two transformers between buses 9-17, and 1516. In this system, the total load in 2013 is 585-MW, Generator 2, and 3 supplied all the power with
excess in generation coming from the swing bus. By reducing generation at buses 2, 3 from their
rated power 490 MW to 298.386 MW, 298.687 MW respectively, the swing bus as a result supplied 0
MW Power.
The current system with the previous information had to be upgraded to accommodate for a load
growth of 1.5% out to 2030. After calculating the load growth, the total load in 2030 is 753.4919 MW,
and the total generation needed including losses was 176.386 MW. To supply this new load demand,
we installed a wind farm 50 miles away from bus 3 with installed capacity of 352.753 MW and a
Natural gas plant with a capacity of 142.7 MW. As instructed in this project, 20% of the load growth
must be supplied from wind and 80% from Natural gas, the swing bus on the other hand has to
remain supplying 0 MW power.
NERC criteria with regards to voltage violations and thermal violations has to be strictly followed, so
under normal conditions, all voltages must be equal or bigger than 0.95, and all the lines must be
loaded within their thermal limits. The system also must stand (N-1) contingency, so in case of
loosing a component in the system, all voltages must be bigger than 0.93, and no thermal violations
in the transmission lines. In our case, we found some voltage violations at buses 10, 13, 4, 5, 6, 8.
As a result, we had to install 5 capacitor banks at buses 10, 13, 4, 5, 7, which boost up the voltage to
0.95 and bigger in the violating buses. After this step, we started the (N-1) contingency for 10%
wind and 90% wind. Some thermal and voltage violations were detected when removing
transmission lines (one line at a time), also by removing one of the transformers, the other
transformer experiences thermal and voltage violations. However, by removing one of the
generators, the swing bus makes up the lost power, so no thermal or voltage violations were noticed
in the system.
To make the system stand (N-1) contingency, we added a third transformer, a total of 6 transmission
lines, and 5 capacitor banks. We started solving for the 90% wind contingency and that fixes both
cases except for one line that had to be added for 10% case, all details of the solution would be
explained in this report. Finally, we calculated the total capital cost of the wind farm, natural gas
plant, and all components added to make the system stand (N-1) contingency, and we reached to a
total cost equals to $683,287,012.
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1. Base Case I (2013):
The first base case consisted of an existing transmission system that contains 161 kV and 69
kV transmission lines, which run through urban, and rural services territory (figure 1). The total
current load in 2013 amounts to 585 MW and 145 Mvar. The red arrows indicate generator
buses.
Figure 1
1.1 Transformers
There are two 69kV-161kV-60MVA transformers at the Siskin bus (9-17) and Crow (15-16)
buses. The transformers have leakage reactances of 34.56ohm. To insert this value into
PSSE, we divided it by Zbase (figure 2).
Figure 2
1.2 Transmission Lines:
Only three types of conductors used in the system, Drake-907A, Dove-726A, Hawk-726A.
Figure 3 shows the connection of each transmission line, and the thermal limit of each one.
Each line parameters were calculated as the following:
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
Per unit R,X =
(𝑅+𝑗𝑋)
𝑍𝑏𝑎𝑠𝑒
𝐵𝑀𝑣𝑎
B=.𝑆𝑏𝑎𝑠𝑒

Per unit

Rate A = 𝑆𝑞(3) ∗ 𝑉 2 ∗ 𝑎𝑚𝑝𝑎𝑐𝑖𝑡𝑦
Figure 3
1.3 Generators:
Each power source is rated 490 MW, with a minimum Volt-ampere reactive limit of 100 MVAr
and a maximum volt-ampere reactive limit of 250 MVAr. Figure 4 Shows generators after
adjusting generators 2, and 3, so the Swing bus supplies 0 MW power.
Figure 4
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1.4 Violations of base case:
After solving the power flow, several buses had voltage violation, which were
solved by installing 5 capacitor banks at buses 4, 5, 7, 10 and 13. (Table 1) shows each
violating bus before and after installing the capacitor banks.
Table 1
1.5 Power flow simulation of Base case 1 (2013):
Diagram of base case 1 after adding the capacitor banks, the diagram was also
double checked for any thermal violations figure 5.
Figure 5
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2. Base Case II (2030):
This base case was done after Adding a load growth of 1.5% out to 2030, adding a wind farm
50 miles away from bus 3, adding 2 transmission lines between the new bus 18 (wind farm) and
bus 3, and also after adding the Natural gas to bus 3.
2.1 Load Growth:
By using this equation 𝑁𝐿 = 𝐸𝐿(1 + 𝑖)𝑛 , we increased the load for each bus by 1.5% out to the
year 2030. (Table 2) Shows the load increased for each bus and the total difference (Total
Generation needed without losses).
Table 2
2.2 Total Generation Needed:
Total Generation needed with losses, which was calculated after solving the power flow is equal
to 176.386 MW. 20% must be supplied by wind and 80% by Natural gas (Table 3).
Table 3
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The Swing bus once again has to supply 0MW power, so after adding the Natural Gas and Wind
farm, we adjusted the swing bus (figure 6).
Figure 6
2.3 Capacity Credit:
Capacity Credit is a convenient and effective way to compare between wind power generation
and a traditional power generation. Since wind is not dispatchable, meaning we do not know
when the wind blow, but we can count on the capacity credit given. In this case, the capacity
credit is 10%, so we can figure out the installed capacity of wind by dividing the 35.2753
by 10%, which amounts to 352.753MW. The handling of capacity credit calculation for 10%
wind and 90% is described in the following sub-sections:
 2.3.1 10% wind:

By multiplying 10% by the installed capacity 352.753, we get the 10% wind, which is the
value we insert in Pgen in PSSE.

Qmax and Qmin can be obtained by dividing Pgen/2, Qmax=Pgen/2, while Qmin=Pgen/2 (figure 7).
Figure 7
 2.3.2 90% wind:

Same procedure as handling the 10% wind except multiplying by 90%. For Qmax
and Qmin, the calculation would be the same as the 10% case see (figure 8). We
reduced the NG to 0 as well as Generations at 2, and 3 so the swing bus
supplies no power.
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Figure 8
2.3 Adding 2 transmission lines:
After adding the wind farm, we added 2 transmission lines between bus 18 and 3. We
calculated the parameters by using these considerations:

For R, the resistance at 50 C temperature is 0.182 (for Dove).

For X, phase –Neutral reactance for 1ft spacing =0.42 ohm/mile, and by adding
this number with 0.2794 log 15.5. We get the total the reactance for the given
spacing which is 15.5 ft. and to get the per unit value, we just multiply the total Xd
by 50 and then divide it by Zbase. And this last step is for calculating R as well.

For B, the capacitive for 1 ft. spacing = 0.0965, and by adding with 0.06831 log
15.5 we get the total, finally by following the same procedure as well as checking
the unit, we can the per unit B.

For Rate A, calculation will be the same as previous lines (Table 4).
Note: When we added any additional lines later, we followed the same procedure.
Figure 9
2.4 Power Flow Simulation for Base Case II (2030):
After solving the power flow, no violations were found. All Voltages were equal or above 0.95
because at this point No (N-1) Contingency analysis was done. Finally, we checked that the
swing bus does not supply power (Figure 10, 11).
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No
violations
Figure 10
2 transmission lines
for wind farm
Figure 11
Note: After checking that in Normal condition the system is within the criteria limit, we are ready
to do the (N-1) contingency for 10% and 90% Wind.
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3. N-1 Contingency
This process can be done, by removing one Generator, one transformer, or one transmission
line at a time. After removing one component at a time, we check for any voltage or thermal
violations. We did this process twice, one when the wind is 10% of its installed capacity, and
one when the wind is 90% of its capacity.
3.1 N-1 contingency for 10% wind:
Done for Transmission lines, Transformers, and generators.
 3.1.1 Simulation of 10% wind: Same as figure 11.
 3.1.2 Transmission lines:
The following (Table 4) shows that by removing the listed T. lines (second row), we get thermal
violations (third row). In the third row, we specified the line that is over loaded with the
percentage of over loading. This table also shows that when removing any of the following lines,
we get some voltage violations in the specified buses. To better understand this table, consider
this example.1:

When we remove line (3-15), line 3-6 gets over loaded and the percentage of
overloading is 107%. Also we get voltage violations at buses 5, 7, 10, 13, 15, and 16.
Table 4
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Simulation of example.1 (figure 12):
Figure 12
 3.1.3 Transformers:
When we remove one of the transformers, the other one gets over loaded, and some
voltage violations are detected in the following buses (Tables 5, 6).
Table 5
Table 6
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Example.2: if removing transformer 1. (Figure 13):
Figure 13
 3.1.4 Generators:
When we remove one of the generators, the swing bus makes up the lost power, so no
voltage or thermal violations were noticed. The following (figure 14), shows an
example.3 if we remove Generator 2.
Swing bus
makes up the
power
Figure 14
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3.2 N-1 contingency for 90% wind:
Same procedure, the only difference this time is that the wind blowing, so we have free power
coming in to the system. After inserting the value for the 90% in the machine tab, and reducing
the natural gas to 0 as illustrated in figure 8, we can start the N-1 contingency for 90% wind.
 3.2.1 Simulation of 90% wind:
Figure 15
 3.2.2 Transmission lines:
We notice in the following table that the violations are more intense for the wind power
is at 90% of its installed capacity. For example, when removing line (3-15), we have 3
thermal violation and 8 voltage violations. By looking at the 2 lines from wind to bus 3,
we can notice that they cannot stand N-1 contingency. So when removing one of them,
the other one gets over loaded. Refer to section 3.1.2 for understanding (Table 7):
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Table 7
Note: Transmission lines in Table 7 were the only lines with voltage and thermal violations,
the other lines were not mentioned since they passed the N-1 Analysis.
 3.2.3 Transformers:
Same as the 10% case except for a slight different in the voltage violations values
(Table 8, 9). Refer to example.2 and figure 13 for illustration.
Table 8
Table 9
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 3.2.4 Generators:
No voltage or thermal violations are detected. Because the swing bus makes up the lost
power. See Figure 8 for understanding the 90% wind.
4. Solution
We started solving for the 90% wind since it had more violations than the 10% case. Once done
for the 90% solution, we checked the solution for the 10% case and it did solve most of the
violations except thermal violation in line 2-11, which we did solve for it later on. The overall
solution with the diagram is explained as follows:
 4.1 90% Wind Solution:
-
We started by adding a new 60 MVA transformer between bus 10, and a new bus
19 “transformer bus”, then connect bus 19 to bus 4, and this was done by adding a
new transmission line type “Dove” with the following parameters (table 10), the
routing chose for this transmission line was calculated by adding the distances
between 10-17, and 4-9.
Table 10
-
By looking at one the three line (3-6), (3-12), and (3-15), we can noticed that by
removing one of these three lines, system experiences the most thermal and voltage
violations. In order to fix this problems, we added a line between 3-5 that has the
routing of 3-6, 5-6, with the following parameters (table 11):
Table 11
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-
When looking at the two lines between the wind bus and bus 3, we can see that by
using Dove for the 90% case, the two lines cannot stand N-1 contingency, see
Figure 15. At first, we tried to use a line with higher ampacity but that did not work, it
may increase the thermal limit but it certainly cannot withstand N-1 contingency.
After all, we decided to add a three lines from bus 18 “wind” to bus 3 using the
cheapest conductor “Dove”, the parameters of each line are described in (Table 12):
Table 12
 4.2 10% Wind Solution:
-
The 90% solution fixed most of the violations in the 10% case except when we
remove either line (2-11), or (2-14) we used to have thermal violation in the
other one, so we added another line with the following parameters (Table 13)
and that conclude the whole solution for the system.
Table 13
 4.3 Diagram of the System After the Solution:
In the following diagram (Figure 16), any pink component is what we added to Base
case I diagram.
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New transmission
line between (2-11)
New transformer
between bus 10 and
19, and T. Line
between (4-19).
3 New T. Lines
from wind to bus 3
New line (3-5)
5 capacitor banks added at the
very beginning
Figure 16
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5. Selling power to a costumer at bus 1
When the wind is at 90% of its capacity and when using the natural gas, we can see in (Figure
17) the power is flowing throw the less resistance lines up to the North to bus 1, so we certainly
can sell power to a costumer at bus 1, and we can sell up to 253.2913 MW.
Figure 17
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6. Economic Analysis:
For the Cost, we have considered many factors while calculating the overall cost of
everything added to solve for the system. The factors considered are the following:

Capital cost which includes the capacity, constructions, labor, financing,
natural gas plants, and the air emissions control.

Government Incentives

Transmission line and capacitor cost

Fuel cost and the overall cost of electricity
 6.1 Transmission Lines Cost:
We have started by calculating the cost of the Transmission lines. For our system,
we have added a total of 6 transmission lines. Our calculations of the total cost of the
transmission lines are shown in (Table 14).
Table 14
 6.2 Substations Cost:
We added 2 busses to the system, we assumed that we have a total of 2 substations.
The cost of one substation is $300000. Calculations of the total price for both of the
two substations are shown in (Table 15).
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Table 15
 6.3 Circuit Breaker Cost:
Assuming each line has a circuit breaker at each end of it, the total circuit breakers for
each line is 2. Since we have a total of 6 transmission lines added to the system, we
have a total of 12 circuit breakers. The total cost of all the circuit breakers are shown
below:
Table 16
 6.4 Transformer cost:
We added to the system one 60MVA transformer. The total cost of the added
transformer is:
 6.5 Capacitors cost:
we added a total of 5 capacitors at the beggining of our solution to solve for the
base case. The capacitors were added to the busses 4,5,7,10,13. The cost of each
capacitor differs from the other since each capacitor has a different value. Below is
the total cost of all the capacitors (Table 17):
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Table 17
 6.6 Natural gas cost:
Calculating the cost of the added natural gas requires us to research for the
overnight cost of it. We did our research and found out that the overnight cost of
natural gas is 802000 $/MW. However, many factors can be considered for natural
gas such as, fuel cost, maintainance cost. So as an estimation, fuel and maintanence
would amounts to of 300,500 $/MW-yr
Natural gas cost = (Overnight cost of NG)*(Capacity of NG)
= (800,000$/MW)*(142.7062)
= $114,164,960+ (300,500)*17 = $119,273,460.
 6.7 Wind cost:
The cost to build a 352.772MW wind farm is calaculated by considering that a 1MW
wind turbine would cost 1.5 Millions. A simple math below gives us the total cost of
wind for our system:
➔
1 MW=1.5Millions
➔ 352.772MW= X
➔ (1.5Millions * 352.772MW)/1 MW = $529,158,000
 6.8 The Overall cost of the system:
Finally, to get the total cost of the system, we add up all the results above. By adding
a total cost of 6 transmission lines, two substations, twelve circuit breakers, one 60
MVA transformer, five capacitors, Natural gas, and wind; we come to a total value of
$688,110,260.
7. Conclusion:
After solving the system against any N-1 contingency, the system can withstand the load
growth and any failure of one compenet at a time. Overall, this project was benefical as it
made us understand the basics of system planning and what to consider when adding any
compnont to the system. It also made us understand how renwable energy is integrated to
an existing system, and the nature of these sources of energy.
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References
1. Ensslin, Milligan, Holttinen, O’Malley, Keane, “ Method to calculate Capacity Credit of
Wind power, IEA Collaboration”, IEEE. Web.2008,
2. Bergen, Vittal, “Power Systems Analysis”, Prentice-Hall, New jersey.2000.
3.
U.S Energy Information Administration, “U.S. Crude Oil, Natural Gas, and NG Liquids
Proved Reserves”, August 2012
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