Case Study
Case Study
For the distribution system shown in Figure 1, the main section has a failure rate of
0.2 fails per km per year and is divided into three sections as shown. The average time
to restoration of the main section is 5 hours. The feeders have failure rates of 0.3 fails
per km per year and average time to restoration of 3 hours. There are
eakers on all
sections and feeders so that any failure can be isolated by its nearest upstream
eaker.
L1
L2 L3
2 km 2 km 3 km
1 km 1 km
Section 1 Section 2 Section 3
Feeder 2 Feeder 3Main Supply
Figure 1: Load feeder section
The load SCDFs and average sizes can be seen in Figure 2. An embedded generator is
to be installed in a back-up configuration on this line. The supplied generator’s cost
data is shown in Table 1.
Table 1: Generator cost data
Lifetime 25 yrs
Capital € 10,000 per MW
O&M 20 c per MWh
Figure 2: SCDFs for loads L1, L2 and L3
a) Calculate the expected inte
uption costs for each section of this system:
Table 2: Expected inte
uption costs (EICs) for each section
section r ??1??1 ??2??2 ??3??3 ∑???? EIC
1
2
3
feeder
2
3
fails hours Total EIC: €______
) Confirm this by calculating the EIC for each load:
Table 3: Expected inte
uption costs (EICs) for each load
load L ????1 ????2 ????3 ????2 ????3 EIC
1
2
3
MW Total EIC: €______
XXXXXXXXXX
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
time [hours]
c
o
s
t
[€
M
W
]
Load L1 (1 MW)
Load L2 (1 MW)
Load L3 (5 MW)
c) Calculate the levelised costs of installation of the generator at each bus, assuming
it provides for all downstream loads (losses excluded).
Table 4: Generator levelized installation cost
Bus 1 Bus 2 Bus 3 L2 L3
Capacity
Capital
O&M
Total: € _____ € _____ € _____ € _____ € _____
d) Calculate the profit/loss associated with each potential installation and find the
optimum installation point for best economic performance of this generator.
Table 5: Profit/loss analysis*
Bus 1 Bus 2 Bus 3 L2 L3
Retrieved EIC
Cost
Total:
* assume each placement only backs up one section or load
e) The generator is to be replaced with a generator with the same capital cost per
MW but different operation and maintenance costs. What is the maximum cost
per MWh in order to maintain a profit (round to the nearest cent per MWh)?