2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 271 -
The main privilege of using this method is considering
forced outage rates (FORs) uncertainties in reliability
assessment.
52
1
1
w
w
I
f
i
EENS
ACCI
N
¦
¦
(3)
Where,
w
EENS
: Expected Energy Not Supplied at each week.
f
N
: Number of affected Customers.
52
1
52
1
(
)
w w
w
total
w
w
EENS C
IEAR
EENS
u
¦
¦
(4)
Where,
w
C
: Customer Interruption Cost ($)
For estimating the weekly FOR of each DG unit, the
paper has obtained the Capacity Credit (CC) of each DG
unit. In the wind power plant, the speed of wind leads to
primary resource uncertainty that has been modeled
through evaluating annual wind regime. In Photo-Voltaic
(PV) plant, the angle of solar radiation affects the power
generation. So, the paper has appraised the solar radiation
by annual radiation curve of mentioned PV plant. For
other DG resources, the paper has assessed their capacity
credit by considering uncertainty in fuel delivery to the
plants. After estimating weekly FOR of DG units, ISO
calculates the reliability at each time stage initially. ISO
studies the reliability indices with considering offers of
DG companies. If the offers are feasible, closure of the
DRMM will be announced by ISO. Otherwise, ISO starts
the assessment if it can present a public
incentive/disincentive in specific time stage to DRMM
participants. The important advantage of this method is
that incentives or penalties have been made according to
a cost that ISO should pay for preserving reliability in
satisfactory level. (5), (6) and (7) represent determination
of incentives/disincentives by ISO in DRMM.
,
,
(
)
ISO w
Offer w
w
ISO w
AENS
AENS
AENS
D
½
°
°
®
¾
°
°
¯
¿
(5)
Where,
w
D
: Incentive/penalty factor.
,
ISO w
AENS
: Desirable AENS for the ISO.
Offer w
AENS
: Offered AENS to ISO by DGENCOs.
52
52
52
,
1
1
1
(
)
w
total
w
w
n m
w
w
w
w
IEAR
D
K
K
D
ª
º
«
»
«
» u
«
»
«
»
¬
¼
¦ ¦
¦
(6)
Where,
total
K
: Total incentive (if +) /penalty (if -).
w
K
: Weekly incentive/penalty.
,
n m
: Impact factors (incentive=n, penalty=m).
1
1
( )
( )
G
g g
g
GENCO g
total
I
i
i
i
P
P
E
K
K
E
u
¦
¦
(7)
Where,
g
P
: Capacity of units in DGENCO-g.
g
E
: Maintenance status of units of DGENCO-g
Therefore, ISO initially obtains the desirable reliability
of distribution network at each time stage. Then, ISO
calculates the reliability indices with considering offers of
DGENCOs. If the offer is feasible, maintenance solution
will be gained. So, DGENCOs recalculate their strategies
based on presented incentives/penalties for attaining a
new Nash strategy by (8).
max,
,
,
,
,
,
,
,
,
,
,
((Pr
)
(1 ))
(
(
))
(
(1 ))
(
(
)
) (
)
w g
g
g w
week G
G week
g w g w
g w w g
g w
g w
g week
g w
g w
Genco g
ice C P
M
Max
prob
pen
E
E
T
E
E
K
u u
ª
º
«
»
u
«
»
«
»
u
«
»
«
»
u u
¬
¼
¦¦ 3
(8)
This process continues until reliability considerations
of system have been respected. Therefore, the final
strategy of DRMM assures the satisfactory level of
reliability and stability of distribution network
adequately. On the other hand, ISO checks the stability of
distribution network by getting power flows in every time
stages (weeks). Getting power flow gives the network
conditions to ISO, especially in maintenance weeks that
ISO can estimate the amount of generation that the
mentioned local distribution network should get from
neighbor areas.
C. Roy Billinton Test System Case Study Results
The RBTS generation system [10] consists of two
DGENCO, with overall 11 large scale distributed
generating units (gas engines). The annual peak load for
RBTS is 185 MW. The load uncertainty is considered 5%
with normal distribution situation for both RBTS and
IEEE RTS. Table I, presents the uncertainty factors of
RBTS. Table II, III and IV show the generation data, the
demand and the price data of RBTS, respectively.
Additional information about single line diagram of
RBTS and the annual load duration curve is mentioned in
[10]. Fig. 2 depicts RBTS linear schema.
