2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 270 -
ISO is responsible for market management. Each DG
company is going to maximize its own payoffs in both
main electricity market and DRMM through its
uncertainties. On the other hand, ISO covers the network
reliability concerns by the DRMM. At first, each DG
company gives its offer in DRMM to the ISO. Then, ISO
informs the DRMM participants by a Market Interface
called: DRMI in cases such as opening/closing time of
DRMM, announcing acceptance or rejection of offers in
each time stage and incentive/disincentive notifications to
DRMM participants.
II. T
HE
M
AINTENANCE
S
CHEDULING
S
OLUTION
In this section, the new maintenance scheduling
method
for
distributed
generation
companies
(DGENCOs) that result to a competitive DRMM has
been fully explained
.
Generally, the main participants of
power market are DGENCOs, and ISO. Independent
system operator undertakes the reliability preservation of
system. In this new solution, all DGENCOs are going to
maximize their own payoffs through a dynamic game.
After finding the Nash Equilibrium, the best strategy of
DGENCOs has been offered to ISO. On the other hand,
ISO assesses the offered Nash strategy in system
reliability point of view by the MCS. ISO can accept the
offer or can present disincentives when reliability of
system is lower than desired level. Further on, the roles of
each market players have been discussed.
A. Distributed Generation Companies in DRMM
In managing systems such as power electricity
markets, main decision making variables are market
participants. For modeling the participants and their
behaviors in the power market, a dynamic game has been
applied. So, the strategy of each DGENCO has been
simulated through a dynamic tree-game based on market
time stages. Thus, if the Nash equilibrium exits in the
market, the market could be converged to this equilibrium
point through Backward Induction method. At this point,
all companies will not feel unsatisfied from their decision
in market. Thus, in this paper the strategy of each DG
company is relied on maximizing DG company's profits
considering both auction and DRMM besides the
decision of other DG companies. Herein, the objective
function of each DGENCO has been written by (1):
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
ice C P
M
Max
prob
pen
E
E
T
E
E
u u
ª
º
«
»
u
«
»
«
»
u
«
»
«
»
u u
¬
¼
¦¦ 3
(1)
Where,
Pr
w
ice
: Weekly Price of selling power to Retailers
for a strategy ($/MWh).
max,
g
P
: Power generated by units in stage t (MW).
g
C
: Cost Function of each DG unit.
,
g w
E
: Maintenance status of units in stage t (1 if
unit goes to maintenance and 0 otherwise).
,
g w
M
: Maintenance Cost of generation units ($).
,
g w
T
: Stability factor that is gained from inherit
stability characteristic of power distribution
network.
,
g week
prob
: Probability of maintenance time
prolongation (%).
,
g w
pen
: Penalty factor for non-on time maintenance
of DGs ($).
Therefore, each DG company solves its own problem
by considering game of other DG companies and
determines its best strategy in DRMM and main power
market. By considering all existing strategies, DG
companies announce ISO if they desire to participate in
DRMM in specific time stage or not. If ISO accepts the
offer of a DG company, the specified units of this
DGENCO will go to maintenance. Otherwise, ISO may
offer incentives/penalties for DG companies before
closing the annual DRMM.
In this situation, each DG company obtains the new
strategy by optimizing its objective function based on
determined incentives or disincentives. This process
continues until ISO announce closing the DRMM and
find the Nash equilibrium at the specific market stage.
B. ISO Roles in DRMM
As it is known, ISO is responsible for DRMM
supervision, protection and improvement of distribution
network reliability and security. For this reason, this
paper has applied the Monte-Carlo Simulation for
assessing comprehensive reliability indices of distribution
network and also determining accurate incentives or
penalties for DRMM. By using Monte-Carlo Simulation,
important reliability indices such as Loss of Energy
Expectation (LOEE) and Expected Energy Not Supplied
(EENS) have been obtained. .
The number of iterations has been considered about
100000.After calculation of these substantial indices by
MCS, the distribution reliability criterions such as:
AENS, ACCI and Interrupted Energy Assessment Rate
(IEAR) have been gained. These indices are shown
respectively by (2), (3) and (4) [9]
.
1
1
1
I
c
i
i
I
I
i
i
i
i
L d
EENS
AENS
N N
¦
¦ ¦
(2)
Where,
c
L
: Load Curtailed (KW).
d
: Duration of interruption (h).
i
N
: Customer-i .
i
EENS
: Expected Energy Not Supplied (MWh).
