Field of the Invention
The present invention relates to an electric power
supply system which performs power supply between a power
consumer having a distributed power source and a power
consumer without a distributed power source.
Background of the Invention
Japanese Patent Application Publication No. 2006-
191748 (JP2006-191748A) discloses a conventional electric
power supply system. In the conventional system, a group of
first power consumers each having a distributed power
source, such as a photovoltaic power generation system, and
a group of second power consumers without the distributed
power source are connected to a common electrical grid, and
accordingly, a surplus power generated in the distributed
power sources of the first power consumers are supplied to
the second power consumers via the common electrical grid as
well as balance of power supply between the first and second
power consumers is managed entirely by a power control
device.
In the conventional electric power supply system
described in JP2006-191748A, an electricity meter separately
measures the amounts of surplus powers supplied from the
first power consumers to the common electrical grid and the
amounts of required powers supplied from the common
electrical grid to the second power consumers, and the power
control device collects the measurement values. Then, the
power control device calculates a selling price of the
surplus power supplied from the first power consumers to the
common electrical grid and a purchase price of the required
power supplied from the common electrical grid to the second
power consumers on the basis of a predetermined trade price.
However, the conventional system determines the
purchase price and the selling price based on the
predetermined trade price regardless of the balance between
supply and demand of the surplus power and the required
power which change daily, and thus price advantages to the
first and second power consumers may decrease.
Summary of the Invention
In view of the above, the present invention provides
an electric power supply system capable of improving price
advantages in trading a surplus power between electric power
consumers.
In accordance with an embodiment of the present
invention, there is provided an electric power supply system
including: a distributed power source provided at one or
more first power consumers; a power line to supply a surplus
power generated by the distributed power source to one or
more second power consumers; and a management device to
manage a trade price of the surplus power supplied via the
power line. The management device determines the trade
price of the surplus power for one or more following days
based on a prediction value of a surplus power amount of the
first power consumer and a prediction value of a required
power amount of the second power consumer for the one or
more following days.
The management device may determine the trade price of
the surplus power for the one or more following days based
on a total prediction value of the surplus power amount of
the first power consumer having an intention to sell a power
and a total prediction value of the required power amount of
the second power consumer having an intention to purchase a
power.
The electric power supply system may further include
terminal units provided at the first power consumer and the
second power consumer, respectively, and conducting data
communications with the management device. The management
device preferably predicts a power generation amount of the
distributed power source and required power amounts of the
first power consumer and the second power consumer for the
one or more following days, calculates the prediction value
of the surplus power amount of the first power consumer for
the one or more following days based on the predicted
amounts, and notifies the terminal unit at the first power
consumer of the prediction value of the surplus power amount
through the data communications.
The terminal unit of the first power consumer
preferably offers the prediction value of the surplus power
amount from the management device to the first power
consumer and notifies the management device of confirmation
information on an intention of the first power consumer to
sell a power through the data communications.
The management device may calculate the total
prediction value of the surplus power amount of the first
power consumer having the intention to sell the power and
the total prediction value of the required power amount of
the second power consumer having the intention to purchase
the power based on the confirmation information from the
terminal unit of the first power consumer, determine the
trade price of the surplus power for the one or more
following days based on the total prediction value of the
surplus power amount and the total prediction value of the
required power amount, and notify the terminal units of the
first and second power consumers of the trade price through
the data communications.
The terminal units of the first and second power
consumers may offer the trade price transmitted from the
management device to the first and second power consumers
and notifies the management device of information on
decisions to sell and purchase the power by the first and
second power consumers through the data communications.
The distributed power source preferably includes a
power generation equipment of a photovoltaic power
generation system or a wind power generation system which
uses a natural energy.
The management device may adjust the trade price based
on a difference between the total prediction value of the
surplus power amount and a total required power amount
actually supplied to the second power consumer on the one or
more following days.
The terminal unit of the second power consumer may
offer a purchase price of a commercial power supplied from
an electricity company to the second power consumer and
notify the management device of seller determination
information presenting which one will be purchased among the
surplus power and the commercial power through the data
communications, and the management device may determine the
purchase price with respect to the second power consumer
based on the seller determination information.
The terminal unit of the first power consumer may
offer to the first power consumer a selling price when the
first power consumer sells the surplus power to an
electricity company and notify the management device of
purchaser determination information presenting where the
surplus power will be sold among the electricity company and
the second power consumer through the data communications,
and the management device may determine the selling price
with respect to the first power consumer based on the
purchaser determination information.
The management device may change the trade price based
on the information on the decisions from the terminal units
of the first and second power consumers and notifies the
terminal units at the first and second power consumers of
the changed trade price through the data communications, and
the terminal units may offer the changed trade price from
the management device to the first and second power
consumers and notify the management device of information on
decisions to sell and purchase the power made by the first
and second power consumer through the data communications.
The present invention improves price advantages in
trading surplus power between electric power consumers.
Brief Description of the Drawings
The objects and features of the present invention will
become apparent from the following description of preferred
embodiments given in conjunction with the accompanying
drawings, in which:
Fig 1 is a block diagram showing a schematic
configuration of an electric power supply system in
accordance with an embodiment of the present invention;
Fig. 2 is a block diagram showing a terminal unit in
accordance with the embodiment of the present invention; and
Fig 3 is a flowchart showing processes of an
operation processing unit of the management device in
accordance with the embodiment of the present invention.
Detailed Description of the Embodiments
Hereinafter, embodiments of the present invention will
be described with reference to the accompanying drawings
which form a part thereof. Throughout the drawings, like
reference numerals will be given to like parts, and
redundant description thereof will be omitted.
Fig 1 is a block diagram showing a schematic
configuration of an electric power supply system in
accordance with the embodiment of the present invention. A
commercial power, e.g., 10 0V/200V single-phase AC, is
supplied from a electrical grid AC of an electricity company
to electric power consumers via a power line Lp. Here,
among the electric power consumers, electric power consumers
having a distributed power source PV and selling an electric
power are referred to as first power consumers A1, A2, and
the like, and electric power consumers without the
distributed power source PV and purchasing an electric power
are referred to as second power consumers B1, B2 and the
like.
Here, each of the first power consumers A1, A2 and the
like is expressed as a first power consumer Ai (i=l/ 2, ...) ,
while each of the second power consumers B1, B2 and the like
are expressed as a second power consumer Bj (j=l, 2, ...) .
Further, all of the first power consumers A1, A2 and the
like is referred to as a first power consumer group Ai,
while all of the second power consumers B1, B2 and the like
are referred to as a second power consumer group Bj.
An electricity meter (EM) M, a distribution board PB,
loads L, a distributed power source PV and a terminal unit
TU are installed at each of the first power consumers Ai.
Further, although not shown, an electricity meter M, a
distribution board PB, loads L and a terminal unit TU are
installed at each of the second power consumers Bj except
for a distributed power source PV.
The electricity meter M measures the amount of power
flowing from the power line Lp to the distribution board PB
(hereinafter, referred to as a "downward power amount") and
the amount of power reversely flowing from the distributed
power source PV to the power line Lp (hereinafter, referred
to as a "upward power amount") separately and transmits the
measurement values to the terminal unit TU via a
transmission line Lx. The electricity meter M is generally
known in the art, and thus a detailed description and
illustration thereof are omitted herein.
The distribution board PB includes a main breaker (not
shown) and branch breakers (not shown) accommodated in a box
and divergingly distributes a power supplied from the
electrical grid AC or the distributed power source PV to the
loads L.
The distributed power source PV is formed of a
generally known grid-connected photovoltaic power generation
system including a solar cell, a power conditioner, a switch
or the like, and reverse flow of power (selling power) to
the power line Lp is executed/stopped by the power
conditioner. Further, the distributed power source PV may
be any power generation equipments using natural energy,
e.g., a wind power generation system, without being limited
to the photovoltaic power generation system.
As shown in Fig. 2, the terminal unit TU includes a
terminal controller 1, a data communications unit 2, an
input reception unit 3, a display unit 4 and an electricity
meter interface (I/F) unit 5. The data communications unit
2 conducts data communications with a management device SS
via a communications line Ls. The electricity meter I/F
unit 5 receives data of a measurement value transmitted from
the electricity meter M via the transmission line Lx and
outputs the data of the measurement value to the terminal
controller 1 in accordance with a general serial
communications interface (RS232C or RS458). The terminal
controller 1 is configured with a CPU, a memory and the like
and transmits the data of the measurement value received
from the electricity meter I/F unit 5 to the management
device SS via the data communications unit 2 and the
communications line Ls.
The display unit 4 includes a display device, e.g., an
LCD monitor, and a drive circuit of the display device to
display various types of information (to be mentioned later)
on the LCD monitor under control of the terminal controller
1. The input reception unit 3 includes a touch panel paired
with the display device of the display unit 4 and outputs an
input received through the touch panel to the terminal
controller 1. Here, the data communications unit 2, the
input reception unit 3, the display unit 4 and the
electricity I/F unit 5 are generally known in the art, and
thus detailed description and illustration thereof will be
omitted herein.
As shown in Fig. 1, the management device SS includes
a data communications unit 10, an operation processing unit
11 and a storage unit 12. The data communications unit 10
conducts data communications with the data communications
unit 2 of the terminal unit TU via the communications line
Ls. The storage unit 12 is formed with a high-capacity
storage device, such as a hard disk and stores a database to
manage information on all power consumers (the first power
consumers Ai and the second power consumers Bj) . In the
database, items (fields) including a prediction value of
required power amount, a prediction value of power
generation amount {only in the first power consumer group
Ai), a prediction value of surplus power amount (only in the
first power consumer group Ai), an intention of power sale
(only in the first power consumer group Ai), an intention of
power purchase (only in the second power consumer group Bj),
a result value of power sale amount {only in the first power
consumer group Ai) , and a result value of power purchase
amount {only in the second power consumer group Bj) are set
for each identification code (ID) allocated to each power
consumer.
The prediction value of required power amount is a
prediction value of the amount of power consumed by the
loads L of each power consumer for the following day. The
prediction value of power generation amount is a predication
value of the amount of a power generated by the distributed
power source PV of the first power consumer Ai for the
following day. Further, the prediction value of surplus
power amount is the amount of electric power obtained by
subtracting the prediction value of the required power
amount of the first power consumer Ai for the following day
from the prediction value of the power generation amount by
the first power consumer Ai for the following day.
The operation processing unit 11 of the management
device SS predicts the power generation amount for the
following day based on the estimated maximum temperature or
the estimated amount of solar radiation for the following
day obtained, through the Internet, from websites (e.g., the
homepage of the Meteorological Administration or a local
weather center) which provide meteorological information ,
such as a weather forecast or the like and the power
generation capacity of each distributed power source PV.
Further, the operation processing unit 11 predicts the
required power amount for the following day based on records
of previous power consumption by each of power consumers
(the first power consumers Ai and the second power consumers
Bj) and weather information. However, there are various
methods to predict the power generation amount or the
required power amount, without being limited to the
foregoing method.
Further, "the intention of power sale" is an intention
about whether or not to provide (sell) the surplus power to
the second power consumer group Bj when a prediction value
of the surplus power amount for a following day is greater
than zero and is selectively made base on an input through
the input reception unit 3 of the terminal unit TU installed
at the first power consumer group Ai. Likewise, "the
intention of power purchase" is an intention about whether
or not to receive (purchase) the surplus power from the
first power consumer group Ai when a prediction value of the
surplus power amount for the following day is greater than
zero and is selectively made based on an input through the
input reception unit 3 of the terminal unit TU installed at
the second power consumer group Bj.
In addition, "the result value of power sale amount"
is a measurement value by each electricity meter M installed
at the first power consumer group Ai (the upward power
amount) and is the amount of electric power provided (sold)
from the first power consumer group Ai to the second power
consumer group Bj . Likewise, "the result value of power
purchase amount" is a measurement value by each electricity
meter M installed at the second power consumer group Bj (the
downward power amount) and is the amount of electric power
received (purchased) by the second power consumer group Bj
from the first power consumer group Ai. The result value of
power sale amount and the result value of power purchase
amount are also calculated by the operation processing unit
11 of the management device SS based on measurement values
by the electricity meters M installed at the respective
power consumers Ai and Bj.
Hereinafter, processes of the operation processing
unit 11 of the management device SS in accordance with the
present embodiment will be described with reference to the
flowchart in Fig. 3.
First, the operation processing unit 11 of the
management device SS predicts the power generation amount
for the following day by the distributed power source PV
installed at the first power consumer Ai and the required
power amount for the following day by the loads L of each of
the first power consumer Ai and the second power consumer Bj
at a particular time (e.g., at 8 pm) every day in step SI.
Then, the operation processing unit 11 predicts the surplus
power amount of each first power consumer Ai for the
following day based on the prediction value of the power
generation amount of each first power consumer Ai and the
prediction value of the required power amount in step S2.
When the prediction value of the surplus power amount
of the first power consumer Ai for the following day is
greater than zero, the operation processing unit 11 of the
management device SS transmits the prediction value of the
surplus power amount and a confirmation request of an
intention to sell power to the terminal unit TU of the first
power consumer Ai through the data communications unit 10.
In addition, the operation processing unit 11 transmits the
prediction value of the required power amount by the second
power consumer Bj and a confirmation request of an intention
to purchase power to the terminal unit TU of the second
power consumer Bj through the data communications unit 10 in
step S3.
Further, in step S3, the display unit 4 of the
terminal unit TU in the first power consumer Ai displays the
prediction value of the surplus power amount for the
following day and the confirmation request of the intention
to sell power, which are received from the management device
SS. Meanwhile, the display unit 4 of the terminal unit TU
in the second power consumer Bj displays the prediction
value of the required power amount for the following day and
the confirmation request of the intention to purchase power,
which are received from the management device SS. When the
input reception units 3 of the terminal units TU in the
power consumers Ai and Bj receive the intention about
whether or not to sell power and the intention about whether
or not to purchase power, the information on the intention
to sell power and the information on the intention to
purchase power are transmitted from the data communications
units 2 of the terminal units TU of the power consumer Ai
and the power consumer Bj to the management device SS via
the communications line Ls, respectively.
The operation processing unit 11 of the management
device SS stores the information on the intention to sell
power and the information on the intention to purchase power
received by the data communications unit 10 in a field of
the intention of power sale and a field of the intention of
power purchase of the respective power consumers Ai and Bj
of the database. Then, the operation processing unit 11
calculates a total prediction value of surplus power amounts
of the first power consumers Ai which have intentions to
sell powers with reference to the database in step S4 and
also calculates a total prediction value of required power
amounts of the second power consumers Bj which have
intentions to purchase power in step S5.
Further, the operation processing unit 11 sets a
trade price for the following day based on the total
prediction value of the surplus power amounts and the total
prediction value of the required power amounts calculated at
step S5, in step S6 and transmits the set trade price to the
terminal units TU of the respective power consumers Ai and
Bj through the data communications unit 10 in step S7.
Herein, when the total prediction value of the surplus
power amounts of the first power consumers Ai having the
intentions to sell power is greater than the total
prediction value of the required power amounts of the second
power consumers Bj having the intentions to purchase power
(in excess of supply}, the operation processing unit 11 sets
the trade price to a relatively low level. On the contrary,
when the total prediction value of the surplus power amounts
is less than the total prediction value of the required
power amounts (in excess of demand) , the operation
processing unit 11 sets the trade price to a relatively high
level.
However, the respective power consumers Ai and Bj may
change the intention to sell power or the intention to
purchase power in view of the trade price which is received
from the management device SS and displayed on the display
units 4 of the terminal units TU. In this case, when the
input reception unit 3 of the terminal unit 3 of the power
consumer Ai or Bj receives a changed intention to sell power
or a changed intention to purchase power, information on the
intention to sell power or to purchase power is transmitted
from the data communications unit 2 of. the corresponding
terminal unit TU to the management device SS via the
communications line Ls in step S8.
The operation processing unit 11 of the management
device SS repeats steps S4 to S8 by the deadline (e.g., by
11 prn) for intention confirmation of step S9. Then, the
operation processing unit 11 determines the trade price for
the following day after the deadline and transmits the
determined trade price to the terminal units TU of the
respective power consumers Ai and Bj through the data
communications unit 10 in step S10.
As described above, in accordance with the present
embodiment, the management device SS predicts the surplus
power amount of the first power consumer group Ai having the
distributed power sources PV for the following day and the
required power amount of the second power consumer group Bj
without a distributed power source PV for the following day
and sets the trade price for the following day based on the
predictions values. Further, the trade price is adjusted
based on the intentions to sell power made by the first
power consumer group Ai and the intentions to purchase power
made by the second power consumer group Bj, the intentions
being made based on the trade price. Thus, as compared with
the conventional electric power supply system, the system of
the present invention is capable of improving price
advantages in trading a surplus power between the power
consumers Ai and Bj.
However, the total predication value of the surplus
power amount of the first power consumer group Ai (the total
predication value of the surplus power amount for a
particular day stored in the database) may not correspond to
the total required power amount (purchased power amount)
actually supplied to the second power consumer group Bj (the
total result value of power purchase amount for the
particular day).
Further, when an electric power is actually supplied,
the length of an electric circuit (the length of the power
line Lp) is not uniform. For example, when the first power
consumers A1 and A2 supply surplus powers to the second
power consumer B1, the length of the power line Lp from the
first power consumer A1 to the second power consumer Bl is
considerably longer than the length of the power line Lp
from the first power consumer A2 to the second power
consumer Bl. In this case, the first power consumer A1
having a longer length of the power line Lp to the second
power consumer Bl is placed in an unfavorable situation in
supplying an electric power as compared with the first power
consumer A2, because an electric circuit having a greater
length involves greater voltage drop in the power line Lp
due to electric resistance and needs to transmit a power at
a relatively high voltage.
Thus, when the total amount of power actually
purchased is less than the total prediction value of the
surplus power amount, the operation processing unit 11 of
the management device SS distributes a total trade price
obtained by multiplying the total purchased power amount by
the trade price (unit price) to the first power consumer
group Ai according to a ratio of the prediction value of
surplus power amount of each first power consumer Ai to the
total prediction value of the surplus power amount. On the
contrary, when the total prediction value of the surplus
power amount is less than the total amount of power actually
purchased, the operation processing unit 11 of the
management device SS distributes total trade price obtained
by multiplying the total amount of power actually sold by
the first power consumer group Ai stored in the database by
the trade price (unit price) to the second power consumer
group Bj according to a ratio of the predicted value of
required power amount of each second power consumer Bj to
the total prediction value of the required power amounts.
In this way, the first power consumer group Ai or the second
power consumer group Bj can get or pay the total trade price
fairly.
As described above, when a difference between the
total prediction value of the surplus power amount and the
total actually required power amount {the actually purchased
power amount) continues to occur for a long time (e.g., on
week), it is preferable that the operation processing unit
11 of the management device SS adjusts the trade price based
on a difference between the total prediction value of the
surplus power amount and the total actually required power
amount.
For example, as a difference obtained by subtracting
the total actually required power amount from the total
prediction value of the surplus power amount increases, the
operation processing unit 11 lowers the trade price.
Further, as the difference obtained by subtracting the total
prediction value of the surplus power amount from the total
actually required power amount increases, the operation
processing unit 11 raises the trade price. The trade price
is adjusted in this manner to increase the number of power
consumers (the first power consumer Ai or the second power
consumer Bj} having an intention to sell power or an
intention to purchase power, thus raising the surplus power
amount sold by the first power consumer group Ai to the
second power consumer group Bj or the required power amount
purchased by the second power consumer group Bj from the
first power consumer group Ai thereby reducing a power not
traded but wasted.
However, it is possible that the second power consumer
group Bj is supplied with a power (purchases a power) from
the electrical grid AC of the electricity company, instead
of being supplied with the surplus power from the first
power consumer group Ai. Here, the management device SS
notifies the terminal unit TU of the second power consumer
group Bj of the purchase price (electric charge) of the
power purchased from the electricity company, and the
display unit 4 of the terminal unit TU displays (offers) the
purchase price. When the input reception unit 3 of the
terminal unit TU in the second power consumer Bj receives a
determination on a seller selected among the first power
consumer Ai and the electricity company, the determination
on the seller is transmitted to the management device SS
from the data communications unit 2 of the terminal unit TU
via the communications line Ls.
The operation processing unit 11 of the management
device SS determines the trade price of the surplus power
based on the determination on the seller received through
the data communications unit 10. In detail, when second
power consumers Bj which selected the first power consumer
Ai as the seller are more than those which selected the
electricity company as the seller, the operation processing
unit 11 sets the trade price of the surplus power to a high
level. When second power consumers Bj which selected the
electricity company as the seller are more than those which
selected the first power consumer Ai as the seller, the
operation processing unit 11 sets the trade price of the
surplus power to a low level.
In this way, the trade price of the surplus power is
adjusted, thereby reducing electric power not traded but
wasted.
Further, it is possible that the first power consumer
group Ai allows a surplus power to reversely flow (sells a
surplus power} to the electrical grid AC of the electricity
company, instead of supplying the surplus power to the
second power consumer group Bj. Here, the management device
SS notifies the terminal unit TU of the first power consumer
group Ai of the selling price of the power sold to the
electricity company, and the display unit 4 of the terminal
unit TU displays (presents) the selling price. When the
input reception unit 3 of the terminal unit TU of the first
power consumer group Ai receives a determination on a
purchaser selected among the second power consumer group Bj
and the electricity company, the determination on the
purchaser is transmitted to the management device SS from
the data communications unit 2 of the terminal unit TU via
the communications line Ls.
The operation processing unit 11 of the management
device SS determines the trade price of the surplus power
based on the determination on the purchaser received through
the data communications unit 10. In detail, when first
power consumers Ai which selected the second power consumer
Bj as the purchaser are more than those which selected the
electricity company as the purchaser, the operation
processing unit 11 sets the trade price of the surplus power
to a relatively low level. When first power consumers Ai
which selected the electricity company as the purchaser are
more than those which selected the second power consumer Bj,
the operation processing unit 11 sets the trade price of the
surplus power to a relatively high level.
In this ways, the trade price of the surplus power is
adjusted, thereby reducing electric power not traded but
wasted. Although the operation processing unit 11 of the
management device SS predicts the surplus power amount and
the required power amount only for the following day in the
present embodiment, it can predict the surplus power amount
and the required power amount, e.g., for from the day after
tomorrow to up to the following one week based on weather
forecasts for the week in the same manner.
While the invention has been shown and described with
respect to the embodiments, it will be understood by those
skilled in the art that various changes and modification may
be made without departing from the scope of the invention as
defined in the following claims.
We Claim:
1. An electric power supply system comprising:
a distributed power source provided at one or more
first power consumers;
a power line to supply a surplus power generated by
the distributed power source to one or more second power
consumers; and
a management device to manage a trade price of the
surplus power supplied via the power line,
wherein the management device determines the trade
price of the surplus power for one or more following days
based on a prediction value of a surplus power amount of the
first power consumer and a prediction value of a required
power amount of the second power consumer for the one or
more following days.
2. The electric power supply system of claim 1, wherein
the management device determines the trade price of the
surplus power for the one or more following days based on a
total prediction value of the surplus power amount of the
first power consumer having an intention to sell a power and
a total prediction value of the required power amount of the
second power consumer having an intention to purchase a
power.
8 . The electric power supply system of claim 2, further
comprising terminal units provided at the first power
consumer and the second power consumer, respectively, and
conducting data communications with the management device,
wherein the management device predicts a power
generation amount of the distributed power source and
required power amounts of the first power consumer and the
second power consumer for the one or more following days,
calculates the prediction value of the surplus power amount
of the first power consumer for the one or more following
days based on the predicted amounts, and notifies the
terminal unit at the first power consumer of the prediction
value of the surplus power amount through the data
communications,
the terminal unit of the first power consumer offers
the prediction value of the surplus power amount from the
management device to the first power consumer and notifies
the management device of confirmation information on an
intention of the first power consumer to sell a power
through the data communications,
the management device calculates the total prediction
value of the surplus power amount of the first power
consumer having the intention to sell the power and the
total prediction value of the required power amount of the
second power consumer having the intention to purchase the
power based on the confirmation information from the
terminal unit of the first power consumer, determines the
trade price of the surplus power for the one or more
following days based on the total prediction value of the
surplus power amount and the total prediction value of the
required power amount, and notifies the terminal units of
the first and second power consumers of the trade price
through the data communications, and
the terminal units of the first and second power
consumers offer the trade price transmitted from the
management device to the first and second power consumers
and notifies the management device of information on
decisions to sell and purchase the power by the first and
second power consumers through the data communications.
4. The electric power supply system of claim 3, wherein
the distributed power source includes a power generation
equipment of a photovoltaic power generation system or a
wind power generation system which uses a natural energy.
5. The electric power supply system of claim 3 or 4,
wherein the management device adjusts the trade price based
on a difference between the total prediction value of the
surplus power amount and a total required power amount
actually supplied to the second power consumer on the one or
more following days.
6. The electric power supply system of any one of claims 3
to 5, wherein the terminal unit of the second power consumer
offers a purchase price of a commercial power supplied from
an electricity company to the second power consumer and
notifies the management device of seller determination
information presenting which one will be purchased among the
surplus power and the commercial power through the data
communications, and the management device determines the
purchase price with respect to the second power consumer
based on the seller determination information.
7. The electric power supply system of any one of claims 3
to 6, wherein the terminal unit of the first power consumer
offers to the first power consumer a selling price when the
first power consumer sells the surplus power to an
electricity company and notifies the management device of
purchaser determination information presenting where the
surplus power will be sold among the electricity company and
the second power consumer through the data communications,
and the management device determines the selling price with
respect to the first power consumer based on the purchaser
determination information.
8. The electric power supply system of any one of claims 3
to 7, wherein the management device changes the trade price
based on the information on the decisions from the terminal
units of the first and second power consumers and notifies
the terminal units at the first and second power consumers
of the changed trade price through the data communications,
and the terminal units offer the changed trade price from
the management device to the first and second power
consumers and notify the management device of information on
decisions to sell and purchase the power made by the first
and second power consumer through the data communications.