JP5722075B2 - Power demand management system - Google Patents

Description

  The present invention relates to a power demand management system that is installed in equipment such as a factory or a building and predicts a power demand value in the equipment.

  For electricity use in factories, etc., the company of the factory negotiates the maximum amount of power used with the power company and concludes a discount contract for power charges. At that time, the maximum power consumption is generally set to a value that is as small as possible so that the discount rate in the discount contract increases.

  In the factory, a power demand management system is installed so that the maximum power consumption is not exceeded, and the demand value at the time of completion of the time period (for example, the time period is 30 minutes) is predicted every day. Then, in the power management system, when there is a risk of exceeding the contracted maximum power consumption based on the prediction of the demand value at the time of completion of the time limit, an alarm is issued and the power consumption to the load in the factory is controlled. .

  As a prior art related to demand management, for example, Patent Document 1 exists. Patent Document 1 discloses a prediction of a demand value at the time of completion of time limit based on the demand value at time of completion of time = the integrated value of current power consumption + (ΔP / Δt) × the remaining time until the completion of time limit. . Here, ΔP is the amount of change in the integrated value of the amount of power supplied from the power company during Δt at the time of prediction.

JP-A-8-63132

  By the way, in the current demand management system, the demand value at the time of completion of the time limit is predicted only based on the change amount of the integrated value of the electric energy supplied from the electric power company. That is, the demand value at the time of completion of the time limit is predicted based only on the change amount of the integrated value of the electric energy supplied from the wide area power system.

  On the other hand, in the future, from the viewpoint of energy saving, it is expected that the introduction of renewable energy power generation devices such as storage batteries and solar cells will proceed to factories. Here, it is predicted that the electric power generated by the renewable energy power generation apparatus and the electric power charged / discharged by the storage battery change rapidly.

  Therefore, in a situation where renewable energy power generation devices, storage batteries, etc. are introduced, the demand value at the time of completion of time limit is predicted based only on the amount of change in the integrated value of the amount of power supplied from the power company as in the past. In such a case, accurate prediction cannot be performed, and as a result, there is a high possibility that demand over will occur.

  Therefore, an object of the present invention is to provide a power demand management system capable of accurately predicting a demand value at the time of completion of a time period even when a renewable energy power generation device or a storage battery is introduced.

In order to achieve the above object, a power demand management system according to the present invention is a power demand management system that is installed in a facility where a load is used and performs power demand management in the facility. A power receiving unit that receives electric power and outputs the electric power to the load in the facility; a renewable energy power generation device that generates electric power to be supplied to the load in the facility using a natural phenomenon; and the monitoring and receiving status from the regional power grid and the power generation state in the renewable energy power generating apparatus, and a demand prediction unit for predicting a time period upon completion demand value, and wherein said Deman de prediction device, the Using the amount of change in the integrated value of the amount of power received by the power receiving unit and the amount of change in the integrated value of the amount of power generated by the regeneration energy power generation device, To predict the limit completion time demand value.

The power demand management system according to the present invention is a power demand management system that is installed in a facility where a load is used and performs power demand management in the facility. The power demand management system receives power from a wide-area power system, A power receiving unit that outputs power to the load in the facility, a storage battery that can charge power and can discharge power to the load, a power reception status from the wide-area power system in the power receiving unit, and the storage battery monitoring the charging and discharging conditions, and a demand prediction unit for predicting a time period upon completion demand value, and wherein said Deman de prediction apparatus, and the amount of change in the integrated value of the amount of power received at the power receiving portion, The demand value at the time of completion of the time limit is predicted using the amount of change in the integrated value of the amount of power charged / discharged by the storage battery.

The power demand management system according to the present invention is a power demand management system that is installed in a facility where a load is used and performs power demand management in the facility. The power demand management system receives power from a wide-area power system, A power receiving unit that outputs power to the load in the facility, a renewable energy power generation device that uses a natural phenomenon to generate power to be supplied to the load in the facility, and can be charged with power. Monitoring the storage battery that can discharge the power of the battery, the power reception status from the wide-area power system in the power receiving unit, the power generation status in the regenerative energy power generation device, and the charge / discharge status in the storage battery, and the completion of time limit a demand prediction unit for predicting a demand value time, and wherein said Deman de prediction device, varying the integrated value of the amount of power received at the power receiving portion With the amount, and the amount of change in the integrated value of the amount of power generated by the renewable energy power generating apparatus, and a change amount of the integrated value of the amount of power charged and discharged in the battery, predicts the timing at the completion demand value.

The power demand management system according to the present invention, Deman de prediction apparatus, and the amount of change in the integrated value of the amount of power received at the power receiving portion, the amount of change in the integrated value of the amount of power generated by the renewable energy power generating apparatus and / or The demand value at the time of completion of time limit is predicted using the amount of change in the integrated value of the amount of power charged and discharged by the storage battery.

  Therefore, even when a storage battery, a renewable energy power generation device, or the like is introduced, the power demand management system according to the present embodiment can accurately predict the demand value at the time of completion of time limit. Therefore, a situation where a demand over occurs can be avoided.

It is a figure which shows schematic structure of the electric power demand management system which concerns on embodiment of this invention. It is a figure which shows the structure by which the demand prediction apparatus 10, the power receiving part 2, the storage battery 4, and the renewable energy electric power generating apparatus 5 are connected so that communication is possible. It is a figure for demonstrating operation | movement of the power demand management system which concerns on embodiment of this invention.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

<Embodiment>
FIG. 1 is a schematic diagram showing a configuration of a power demand management system according to an embodiment of the present invention.

  The power demand management system is a factory or a building where a plurality of loads 3 that operate by receiving power supply are used (hereinafter, a place such as a factory or a building where the plurality of loads 3 are used is referred to as “equipment”. ) And manage the power demand of the equipment.

  As shown in FIG. 1, the power demand management system according to the present embodiment includes a demand prediction device 10, a power receiving unit 2, a load 3, a storage battery 4, and a renewable energy power generation device 5.

  The power receiving unit 2 receives power supplied from the wide-area power system 6 (that is, a power company) and outputs the power to the load 3 or the like in the facility. The power receiving unit 2 is a boundary between the wide-area power system 6 and the power system on the facility (in FIG. 1, illustrating a factory) side. Here, in FIG. 1, only one load 3 is shown for simplification of the drawing, but a plurality of loads 3 exist in a factory or the like. Examples of the load 3 include a production line device, a measurement device, a test device, an air conditioner, and a lighting device.

  The storage battery 4 is installed in the power system on the facility side. The storage battery 4 can charge the power output from the power receiving unit 2 or the power generated and output by the renewable energy power generation device 5. The storage battery 4 can also output the discharged power to the load 3 by discharging the power. In addition, the number of the storage batteries 4 installed on the facility side is not limited to one and may be plural.

  The renewable energy power generation device 5 is installed in a power system on the facility side. The renewable energy power generation device 5 is a power generation device that can generate power using a natural phenomenon, such as a solar cell power generation device. The electric power generated by the renewable energy power generation device 5 is output to the load 3 and may contribute to the charging of the storage battery 4. In addition, the number of the renewable energy power generation devices 5 installed on the facility side is not limited to one and may be plural.

  The demand prediction device 10 is installed on the facility side, and is connected to the power receiving unit 2, the storage battery 4, the renewable energy power generation device 5 and the like via a network communication network so as to be capable of bidirectional communication as shown in FIG. Yes. The demand prediction device 10 uses the network configuration shown in FIG. 2 to receive power from the wide-area power system 6 in the power receiving unit 2, power generation status in the regenerative energy power generation device 5, and charge / discharge status in the storage battery 4. Are monitored and managed. Note that the demand prediction apparatus 10 can also monitor and manage the power consumption of the load 3 through the monitoring and management. Then, the demand prediction device 10 predicts the demand value at the time of completion of time limit based on the monitoring / management.

  Next, a method for predicting a demand value at time limit completion in the demand prediction apparatus 10 will be described with reference to FIG.

  In this embodiment, the demand time period is assumed to be 30 minutes (in this case, the average power used every 30 minutes is determined as the contract power amount at the time of contract, and the actual time limit completion demand value in the factory is It is necessary not to exceed the contracted electric energy).

  In addition, the demand prediction apparatus 10 always predicts the demand value at time completion, but in the following description, as an example, a method for predicting the demand value at time completion at time t, which is the time when time is not completed, will be described. To do. That is, as shown in FIG. 3, the time t is the time from the start of the time limit to the measurement time.

  In addition, the continuous line part to time t of FIG. 3 has shown transition of the integrated value of the power consumption amount of the load 3 to time t. Also, the horizontal axis in FIG. 3 is time (minutes), while the vertical axis in FIG. 3 is the integrated value (KW) of the electric energy.

  Through the network shown in FIG. 2, the demand prediction device 10 is configured so that the power value of power received by the power receiving unit 2, the power value of power charged / discharged by the storage battery 4, and a renewable energy power generator The power value of the power generated at 5 is received, and each received value is monitored and managed. From the monitoring and management of these power values, the demand prediction value 10 can also grasp the integrated value of the power consumption of the load 3.

  At time t, the demand prediction device 10 is charged with the amount of change in the integrated value of the amount of power received by the power receiving unit 2, the amount of change in the integrated value of the amount of power generated by the renewable energy power generation device 5, and the storage battery 4. The demand value P ′ at the time of completion of time limit at time t is predicted using the change amount of the integrated value of the electric energy to be discharged.

  For example, first, the demand prediction apparatus 10 calculates the integrated value P of the power consumption amount of the load 3 at the time t which is the prediction time. The demand prediction device 10 always monitors and manages the power reception status of the power receiving unit 2, the charge / discharge status of the storage battery 4, and the power generation status of the renewable energy power generation device 5 in the calculation of the integrated value P of the power consumption. So it is possible. Here, the time t and the integrated value P of the power consumption at the time t are illustrated in FIG.

  In addition, the demand prediction device 10 calculates the change amount ΔP of the integrated value of the power consumption amount in the load 3 from the time t−Δt to the time t. Here, “Δt” is a minute time interval set in advance.

  Here, in the prediction method of the timed completion demand value P ′ according to the present invention, in the calculation of the change amount ΔP of the integrated value of the power consumption amount of the load 3, the change amount of the integrated value of the power amount received by the power receiving unit 2. In addition, the amount of change in the integrated value of the amount of power charged / discharged by the storage battery 4 and the amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device 5 are also used.

  For example, at time t, the demand prediction device 10 (change amount ΔPx of the integrated value of the amount of power received by the power receiving unit 2) + (regenerative energy power generation) between Δt {= (t) − (t−Δt)} at time t. The change amount ΔP (= ΔPx + ΔPy + ΔPz) is calculated from the change amount ΔPy of the integrated value of the electric power generated by the device 5 + (the change amount ΔPz of the integrated value of the electric energy charged / discharged by the storage battery 4).

Here, ΔPx is P2 _t −P2 _t−Δt . Note that P2 _t is an integrated value of the amount of power received by the power receiving unit 2 at time t, and P2 _t-Δt is an integrated value of the amount of power received by the power receiving unit 2 at time t−Δt.

ΔPy is P5 _t −P5 _t−Δt . P5 _t is an integrated value of the amount of power generated by the renewable energy power generation device 5 at time t, and P5 _t-Δt is an integrated value of the amount of power generated by the renewable energy power generation device 5 at time t-Δt. is there.

ΔPz is P4 _t −P4 _t−Δt . P4 _t is an integrated value of the amount of power charged / discharged by the storage battery 4 at time t, and P4 _t-Δt is an integrated value of the amount of power charged / discharged by the storage battery 4 at time t-Δt. Here, the discharge by the storage battery 4 is “plus”, and the charge by the storage battery 4 is “minus”.

  Here, FIG. 3 also shows the time Δt and the amount of change ΔP of the integrated value of the power consumption at time Δt at time t.

  Next, the demand prediction apparatus 10 calculates the remaining time until the completion of the time limit at the time t which is the prediction time. In the above description, the time period T from the time period start time to the time period completion time is 30 minutes. Therefore, the demand prediction apparatus 10 calculates (T−t), that is, (30−t).

  Then, the demand prediction apparatus 10 predicts the demand value P ′ at the time of completion of the time period at the time t, which is the measurement time, using P ′ = P + (ΔP / Δt) × (T−t). The value of each term on the right side of the calculation formula is calculated in advance by the demand prediction device 10 as described above.

  FIG. 3 shows the time limit completion demand value P ′ at time t. On the other hand, in FIG. 3, a target demand value is set in advance. The target demand value is a value determined by the contract power amount.

  Note that the demand prediction apparatus 10 is provided with a display unit and the like, and displays the timed completion demand value P ′, the value of each term of the calculation formula, the target demand value, and the like as the result of the calculation formula. Yes.

  When the timed completion demand value P ′ at time t exceeds the target demand value, the demand prediction device 10 issues an alarm and notifies the user of the matter. The user who has received the alarm can disconnect the load 3 and reduce the power used by the load 3.

  On the other hand, when the demand prediction device 10 displays that the time-completed demand value P ′ is a value with a margin with respect to the target demand value, the user can input the load 3 or the like. An increase in power consumption of the load 3 can be implemented.

  In addition, the above calculation is performed at any time during the time period (30 minutes), and when the time period (30 minutes) elapses, the next time period (30 minutes) is started, and at any time during the next time period (30 minutes). The above calculation is performed. Thus, the time is divided by the time period (the time period continues without a break), and the demand prediction value apparatus 10 calculates the time-completed demand value P ′ at any time in each time period. And the demand prediction apparatus 10 performs the comparison process with the said calculation result and a target demand value, and performs a predetermined | prescribed warning and a predetermined | prescribed display.

  In the above description, both the storage battery 4 and the renewable energy power generation device 5 are installed in the facility. However, the storage battery 4 is not installed in the facility and only the renewable energy power generation device 5 is installed (the former configuration), or the renewable energy power generation device 5 is not installed in the facility and only the storage battery 4 is installed. You may employ | adopt the structure (latter structure) installed.

  In the case of the former configuration, matters relating to the storage battery 4 (the term of the storage battery 4 in the above formula) are omitted in the above calculations. In other words, in the prediction of the demand value P ′ at the time of completion of the time limit, the amount of change in the integrated value of the electric energy due to charging / discharging in the storage battery 4 is always treated as zero. On the other hand, in the case of the latter configuration, matters relating to the renewable energy power generation device 5 (the term of the renewable energy power generation device 5 in the above formula) are omitted in each calculation. In other words, in the prediction of the demand value P ′ at the time of completion of the time limit, the amount of change in the integrated value of the electric energy due to the power generation by the renewable energy power generation device 5 is always treated as zero.

  As described above, in the power demand management system according to the present embodiment, the demand prediction device 10 is charged not only by the change in the integrated value of the electric energy at the power receiving unit 2 that receives power from the wide area power system 6 but also by the storage battery 4. Considering the amount of change in the integrated value of the electric energy to be discharged and / or the amount of change in the integrated value of the electric energy generated by the renewable energy power generation device 5, the demand value P ′ at the time of completion of the time limit is predicted Yes.

  Therefore, even when the storage battery 4 or the renewable energy power generation device 5 is introduced, the power demand management system according to the present embodiment can accurately predict the demand value P ′ at the time of completion of time limit. Therefore, a situation where a demand over occurs can be avoided.

  Note that the renewable energy power generation device 5 such as a solar battery is a power generation utilizing a natural phenomenon, and thus a sudden change in the power generation state occurs. In consideration of recent performance of the storage battery 4, the charge / discharge capability is improved, and a large amount of power can be charged / discharged in a short time. Therefore, the effect of the power demand management system according to the present embodiment is more effective in a situation where an abrupt power change amount in the renewable energy power generation device 5 and a sudden power change amount in the storage battery 4 are scheduled.

  In addition, an external system (not shown) for predicting the amount of power generated by the renewable energy power generation device 5 is provided, and the demand prediction device 10 determines the predicted power generation amount of the renewable energy power generation device 5 A configuration of receiving from an external system via a communication network is also conceivable.

  Moreover, the structure by which the charging / discharging amount of the storage battery 4 is planned beforehand from a production plan etc., and the planned charging / discharging electric energy of the said storage battery 4 is preset by the demand prediction apparatus 10 is also considered.

  In the case of each configuration as described above, the demand prediction device 10 predicts at the regenerative energy power generation device 5 between P ″ = P + (ΔP / Δt) × (T−t) − {(T−t). The time-completed demand value P ″ at time t, which is the measurement time, is predicted using the generated power amount} ± {planned charge / discharge power amount in the storage battery 4 between (T−t)}. That is, the demand prediction device 10 also takes into account the predicted power generation amount in the regenerative energy power generation device 5 in the remaining time until the time limit and the planned charge / discharge power amount in the storage battery 4 in the remaining time until the time limit. A demand value P ″ is predicted.

  Here, in “± {planned charge / discharge power amount in the storage battery 4 between (T−t)}” in the above formula, ± + is the case of charging the storage battery 4, and ± − is the storage battery 4. This is the case of discharge. Further, each term of “P + (ΔP / Δt) × (T−t)” in the above formula is the same as each term of the prediction formula of the timed completion demand value P ′.

  Moreover, although the demand prediction apparatus 10 has received the predicted generated power amount of the renewable energy power generation apparatus 5 from the external system, a configuration in which the planned charge / discharge power amount of the storage battery 4 is not set in the demand prediction apparatus 10 can be assumed. . In the case of such a configuration, the demand prediction apparatus 10 predicts the generated power generated by the renewable energy power generation apparatus 5 between P ″ = P + (ΔP / Δt) × (T−t) − {(T−t). Quantities} are used to predict the demand value P ″ at the time of completion of the time period at time t, which is the measurement time.

  In contrast, the planned charge / discharge power amount of the storage battery 4 is preset in the demand prediction device 10, but the demand prediction device 10 does not receive the predicted power generation amount of the renewable energy power generation device 5 from the external system. A configuration can also be assumed. In the case of such a configuration, the demand prediction device 10 is configured such that P ″ = P + (ΔP / Δt) × (T−t) ± {planned charge / discharge electric energy in the storage battery 4 between (T−t)}. Is used to predict the demand value P ″ at the time of completion of the time period at the time t, which is the measurement time.

2 Power receiving unit 3 Load 4 Storage battery 5 Renewable energy power generation device 6 Wide area power system 10 Demand prediction device P Integrated value of the amount of power supplied to the load at the time of prediction P ′, P ″ Prediction value of demand value at time of completion

Claims (9)

A power demand management system that is installed in a facility where a load is used and performs power demand management in the facility,
A power receiving unit that receives power from a wide-area power system and outputs the power to the load in the facility;
Renewable energy power generation device that performs power generation of power supplied to the load in the facility using a natural phenomenon;
A power prediction unit that monitors a power reception status from the wide-area power system in the power reception unit and a power generation status in the regenerative energy power generation device, and predicts a demand value at time completion,
The Deman de prediction apparatus,
Using the amount of change in the integrated value of the amount of power received by the power receiving unit and the amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device, predicting the demand value at the time of completion of the time limit,
A power demand management system characterized by that. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ′ = P + (ΔP / Δt) × (T−t),
here,
P ′ is a predicted value of the timed completion demand value,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device) between Δt.
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
The power demand management system according to claim 1. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ″ = P + (ΔP / Δt) × (T−t) − {predicted power generation amount in the renewable energy power generation apparatus between (T−t)},
here,
P ″ is a predicted value of the demand value at the time of completion of the time limit,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device) between Δt.
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
The power demand management system according to claim 1. A power demand management system that is installed in a facility where a load is used and performs power demand management in the facility,
A power receiving unit that receives power from a wide-area power system and outputs the power to the load in the facility;
A storage battery capable of charging power and discharging power to the load;
A power prediction unit that monitors a power reception status from the wide-area power system in the power reception unit and a charge / discharge status in the storage battery, and predicts a demand value at the time of completion of a time limit,
The Deman de prediction apparatus,
Using the amount of change in the integrated value of the amount of power received by the power receiving unit and the amount of change in the integrated value of the amount of power charged / discharged by the storage battery, predict the demand value at the time of completion of the time limit,
A power demand management system characterized by that. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ′ = P + (ΔP / Δt) × (T−t),
here,
P ′ is a predicted value of the timed completion demand value,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power charged / discharged by the storage battery) between Δt.
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
The power demand management system according to claim 4. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ″ = P + (ΔP / Δt) × (T−t) ± {planned charge / discharge electric energy in the storage battery between (T−t)},
here,
P ″ is a predicted value of the demand value at the time of completion of the time limit,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power charged / discharged by the storage battery) between Δt.
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
+ In ± is “charge”,
− In ± is “discharge”,
The power demand management system according to claim 4. A power demand management system that is installed in a facility where a load is used and performs power demand management in the facility,
A power receiving unit that receives power from a wide-area power system and outputs the power to the load in the facility;
Renewable energy power generation device that performs power generation of power supplied to the load in the facility using a natural phenomenon;
A storage battery capable of charging power and discharging power to the load; and
A demand prediction device for monitoring a power reception status from the wide-area power system in the power reception unit, a power generation status in the regenerative energy power generation device, and a charge / discharge status in the storage battery, and predicting a demand value at the time of completion of time limit Have
The Deman de prediction apparatus,
The amount of change in the integrated value of the amount of power received by the power receiving unit, the amount of change in the integrated value of the amount of power generated by the regeneration energy power generation device, and the amount of change in the integrated value of the amount of power charged / discharged by the storage battery Using the timed completion demand value to predict,
A power demand management system characterized by that. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ′ = P + (ΔP / Δt) × (T−t),
here,
P ′ is a predicted value of the timed completion demand value,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device) + (charge / discharge by the storage battery between Δt. The amount of change in the integrated amount of power)
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
The power demand management system according to claim 7. The demand prediction device includes:
Based on the following formula, predict the demand value at the time of completion of the time limit,
P ″ = P + (ΔP / Δt) × (T−t) − {predicted power generation amount in the regenerative energy power generation device between (T−t)} ± {(T−t) in the storage battery Planned charge / discharge energy},
here,
P ″ is a predicted value of the demand value at the time of completion of the time limit,
P is an integrated value of the amount of power supplied to the load at the time of prediction.
Δt is a preset time interval,
ΔP is (amount of change in the integrated value of the amount of power received by the power receiving unit) + (amount of change in the integrated value of the amount of power generated by the regenerative energy power generation device) + (charge / discharge by the storage battery between Δt. The amount of change in the integrated amount of power)
T is the time from the start of the time period to the time of completion of the time period,
t is the time from the start of the time limit to the prediction time,
+ In ± is “charge”,
− In ± is “discharge”,
The power demand management system according to claim 7.

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