Transcript A Comprehensive Framework for the Structure and Operation

Leader-Follower Framework For
Control of Energy Services
Ali Keyhani
Professor of Electrical and Computer
Engineering
The Ohio State University
[email protected]
614-292-4430
Problem Definition
• Profit motives by market players results in
– Economic efficiency when market is competitive
– Disaster when market power is present
• Casazza
points out that the operational time constant
for electric power is zero, and the planning time constant
for electric energy services is two to 10 years. Casazza
presents an excellent analysis of how free market planning
and operation of electric services have created many new
problems in security and reliability of electric energy
services in a paper entitled “ Electricity Choice: Pick your
Poison”
Logical Solution
• Monitor the market for competitiveness on
an ongoing basis
• Proactively influence market operation if
market power is detected
– Practically all existing market monitoring
functions work in a reactive mode
• Delays of up to several month when reacting to a
market power situation
Effective Solution - proposed
• Constantly monitor market operation and
proactively influence the market
– Address system reliability (source of market power) at
all times
– Market would function freely in the absence of market
power
• seasonal or geographical
– Allow rational profit for market players at all times
Effective Solution - proposed
• Key to this solution
– A Market Monitoring Board (MMB) :
• Uses historical market data, current balance of supply and
demand, underlying power system state, and prevailing
reliability requirements to identify market competitiveness
and send timely signal to participants
• Use the Leader Follower Market Structure, and
determine required spinning reserve energy
under the MMB control in order to ensure that
required security and reliability of the system are
attained.
MARKET MONITORING BOARD
(MMB): Ensures a competitive market in
light of system reliability/security
requirements and market power concerns.
ENERGY
MARKETPLACE:
Matches supply from power
plants and demand from
retailers.
State
Security
Reserves
Deman
d Bids
Supply
Bids
INDEPENDENT SYSTEM OPERATOR
(ISO): Operates the power system.
Suppliers/
Power
Brokers
Demand
customer/
Retailers
Market
Competitivenes
s Functions
Market
Price
Signals
Figure 1. Leader-Follower Market Frame Work for Control
of Energy Services
Market Monitoring Board
• MMB Calculates Market Competitiveness
Function (MCF) and send to all market players
– MCF will establish the foundation for bidding
behavior of the market players
– Conformance with MCFs will ensure that the
affected energy market will function both reliably
and competitively
Market Monitoring Board.. An
Active Player
•The MMB will estimate the cost of the load
being served, act as a player, and select a load
response program to supply the spinning
reserve requirements.
Develop intelligent Agent based algorithms for
computation of the value of the load loss
Market Competitiveness Function
• MCFs are computed based on the leader-follower
optimization algorithms of Stackelberg
• MCFs are based on rational profit motives of
market players and power system reliability
requirements
Market Competitiveness Function
• Address long term reliability and adequacy of
energy systems
– Require adequate capacity in the face of growing
energy demands with the right mix of fuel supply
– Require generators to have the right dynamic
responses if the system is to remain stable in the
event of an outage
– Coordinate between transmission systems,
generating systems and load centers to ensure
generators do not block each other
Solution Algorithm
• Forecast system requirements -- loads, reserves
• Forecast market players cost plus rational profit
• Run a production simulation or OPF model to
determine desired TARGET quantity and price for
each participating generator
• Formulate the global leader-follower optimization
problem and evaluate MCFs
Solution Algorithm
• Send MCFs to market participants and based on
market conditions
– If market is competitive (there are no reliability
concerns) all market players are allowed to ignore
MCF
– If market power is present all market players must
comply with MCFs when preparing their energy bid
Mathematical Formulation
•
•
Decision makers:: MMB is the leader and Players
Leader declares the constraints of participating in the
leader-proposed market opportunities and followers
who are interested in the market, but must satisfy the
leader’s constraints.
• MMB with the decision control variable vector x , and
the followers as market players with decision control
variable y.
• The constraints are defined as MCF. The market
players are optimizers who are interested in
maximizing their payoff function by knowing MCF.
That is for some x = Y, the leader objectives are
satisfied.
MMB convex objective
function can be defined
as:
•
Mathematical Formulation
• Designate the decision control variables for player “i”
p
• as in yi (k )
MW for the quantity of power
with superscript “p” and
yip (k )
•
yi
p
• In $/MWh to be the price offered to the auction market at
a bus ”n”.
•
• Designate
xip (k )
•
• in MW for the quantity of power with
superscript “p” and
p
i
x
(k )
• in $/MWh under the MMB controls at bus
“n”.

i
p
i
p
i
G (y , x , x , y ) 
n
p
i
mn p
m
n
p
2
p p
2
(
y
(
k
)
y
(
k
))

(
x
x
(
k
))
 i
 i i
i
i 1
i 1
• n=1,2,… N
(4)
• The above equation describes the cost of the
system operation at bus “n” from the perspective
of the MMB in $/hour. Note that since the MMB
has control over the load and/or system reserve,
the MMB is also a player in the market, and it can
influence the market players’ decision to make a
rational offer at bus ”n”. Note also,
yi (k )
•
The above equation describes the cost of the system operation at bus “n” from
the perspective of the MMB in $/hour. Note that since the MMB has control
over the load and/or system reserve, the MMB is also a player in the market,
and it can influence the market players’ decision to make a rational offer at bus
”n”. Note also,
p
i
yi (k )  y i (k ) y (k )
p
•
(5)
p
i
xi (k )  x i (k ) x (k )
p
•
•
where
is in $/hour price offer for generator “i” and
i
i
is $/hour for the cost of load response curtailment or the reserve provided
by
the MMB.
y (k )
x (k )
• . Let us consider the simple constraint that
the MMB will be interested in as expressed
by the scheduled power injections at each
system bus “n”.
mn
•
p
p
p
p
2
Cn ( yi , xi )   ( yi (k )  xi (k ))
i 1
• n=1,2, .. , N
(6)
• The MMB will perform the optimum power
flow (OPF) and determine the rational price
offer and the amount of the schedule for
each participating generator “i” at bus “n”
as target values to formulate the MCF
functions.
• Designate in Xi(k) $/hour by the MMB as its target cost for the
generator type i.
• Designate
and
as the desired MMB for
Yi p (k )
Yi p (k )
• the active power and price to be selected by the players.
• From the MMB’s perspective, the optimal operation of the system
can be achieved if the market players select the
and
Yi
p
(k )
p
Yi (k )
• such that the hourly cost of operation of generator “i” is equal to
Xi(k). To induce the players to select the MMB targets, the MMB
defines the MCFs as follows:
MCF Function
xi (k)  X i (k )   i (k )( y (k )  Yi (k ))
p
i
p
i
p
• (7)
i (k )( y (k )  Yi (k ))
p
Conclusions
• Market Forces can not plan the planning and
operation of Power System.
• A framework for planned operation is
presented where the state MMB will be an
active player in the market. This concept is the
same as “National Oil Reserve” Policy.
• A solution methodology to control energy
services within the restructured electricity
markets is presented.
• Planned operation of the system is essential to
ensure stable prices.
• Without planned operation, the electric energy
system will be subjected to a cycle of
deficiencies in energy production that will
eventually lead to a cycle of bottlenecks and
excessive generation.
• This cycle will repeat itself, if it is left to market
forces alone to plan the operation of the system.
This will result in substantial dislocation in the
economy.
• If you interested in more detail of this
presentation go to:
• http://eewww.eng.ohio-state.edu/ems
• And down load the paper A. Keyhani,
Leader-Follower Framework For Control of
Energy Services” IEEE Transaction on
Power Systems (in print) Paper Number ;
2001TR374