Control device, consideration calculation device, power system, and computer-readable medium having recorded thereon a program

In order to output sufficient reactive power for voltage stabilization of a utility grid, and calculate an appropriate consideration according to an amount of the output reactive power, is provided a control device for controlling a distributed power source connected to the utility grid, comprising: a range setting unit where an allowable range of reactive and active powers output at normal times is set; an output control unit for controlling the reactive and active powers supplied from the distributed power source to the utility grid within the allowable range set in the range setting unit; and a reception unit for receiving, from a command device in the utility grid, an excess output command indicating that the reactive power exceeding the allowable range should be output, wherein the output control unit is for outputting the reactive power out of the allowable range when the reception unit receives the excess output command.

BACKGROUND

1. Technical Field

The present invention relates to a control device, a consideration calculation device, a power system, and a computer-readable medium having recorded thereon a program.

Distributed power sources such as solar power generation devices have been widely used. Power generated by a distributed power source is converted into alternating current via a control device such as a power conditioner, to be supplied to a utility grid. Imparting a reactive power control function to the power conditioner suppresses voltage fluctuation of the utility grid caused by a fluctuation of the generated power. For example, a technique has been proposed for predicting and outputting controllable maximum reactive power from the present to a predetermined time later based on predicted maximum power and rated capacity of the power conditioner (see Patent Document 1, for example).

2. Related Art

It is desirable that control devices such as power conditioners can output sufficient reactive power for voltage stabilization of a utility grid. It is also desirable that an appropriate consideration be calculated according to an amount of the output reactive power.

SUMMARY

According to a first aspect of the present invention, a control device is provided. The control device may control a distributed power source connected to a utility grid. The control device may include a range setting unit. The range setting unit may be set with an allowable range of reactive and active powers output at normal times. The control device may include an output control unit. The output control unit may control the reactive and active powers supplied from the distributed power source to the utility grid within the allowable range set in the range setting unit. The control device may include a reception unit. The reception unit may receive, from a command device in the utility grid, an excess output command indicating that the reactive power exceeding the allowable range should be output. The output control unit may output reactive power out of the allowable range when the reception unit receives the excess output command.

The range setting unit may be set with a power factor range of the reactive and active powers as the allowable range. The output control unit may output the reactive power out of the power factor range when the reception unit receives the excess output command.

The output control unit may increase the reactive power supplied to the utility grid while maintaining the active power supplied to the utility grid, when the reception unit receives the excess output command.

The output control unit may decrease the active power to increase the reactive power, when apparent power in case of increasing the reactive power in response to the excess output command, exceeds maximum power that can be supplied to the utility grid.

The control device may further include a power conditioner. The power conditioner may receive power from the distributed power source, and output power to the utility grid. Maximum power that can be output by the power conditioner may be larger than maximum power that can be output by the distributed power source.

According to a second aspect of the present invention, a consideration calculation device is provided. The consideration calculation device may include a consideration calculation unit. The consideration calculation unit may calculate, based on a power amount of the reactive power supplied to the utility grid by the control device according to any of the above, a consideration paid to an administrator of the control device. The consideration calculation device may include a power detection unit. The power detection unit may detect the power amount of the reactive power supplied to the utility grid by the control device according to any of the above.

The consideration calculation unit may calculate the consideration based on an excess power amount of the reactive power output exceeding the allowable range.

The consideration calculation unit may calculate the consideration based on an increased power amount obtained by increasing power of the reactive power in response to the excess output command.

The consideration calculation unit may calculate, further based on a consideration paid for the active power, a consideration paid for the reactive power.

According to a third aspect of the present invention, a power system is provided. The power system may include a plurality of the control devices according to any of the above. The power system may include a notification device for notifying each of the control devices of the excess output command.

The notification device may set, based on the active power supplied to the utility grid by each distributed power source, the reactive power to cause each distributed power source to output.

The notification device may preferentially cause a distributed power source that can increase a larger amount of reactive power in a range where the active power supplied to the utility grid is not decreased, to increase the reactive power.

According to a fourth aspect of the present invention, is provided a computer-readable medium having recorded thereon a program that when executed by a computer, causes the computer to perform operations comprising calculating, based on a power amount of reactive power supplied to a utility grid by a control device, a consideration paid to an administrator of the control device. The control device may control a distributed power source connected to the utility grid. The control device may comprise a range setting unit. The range setting unit may be set with an allowable range of reactive and active powers output at normal times. The control device may include an output control unit. The output control unit may control the reactive and active powers supplied from the distributed power source to the utility grid within the allowable range set in the range setting unit. The control device may include a reception unit. The reception unit may receive, from a command device in the utility grid, an excess output command indicating that the reactive power exceeding the allowable range should be output. The output control unit may output the reactive power out of the allowable range when the reception unit receives the excess output command. The program, when executed by a computer, may cause the computer to perform operations comprising: detecting the power amount of the reactive power supplied to the utility grid by the control device. The program may be a program that causes the computer to function as the consideration calculation device according to any of the above.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the claimed invention. Moreover, not all combinations of features described in the embodiments are essential to solutions of the invention.

FIG.1shows a power system1according to one embodiment of the present invention. The power system1may include distributed power sources20-1and20-2(may be collectively referred to as a distributed power source20), control devices100-1and100-2(may be collectively referred to as a control device100), and consideration calculation devices200-1and200-2(may be collectively referred to as a consideration calculation device200). The number of each configuration is not limited to that shown inFIG.1.

The distributed power sources20-1and20-2may be respective power sources such as solar panel-based solar power generation device, wind power generation device, electric vehicle, and fuel cell power generation device. In this example, the distributed power sources20-1and20-2are solar power generation devices. The distributed power source20-1is electrically connected to a utility grid30via the control device100-1. Likewise, the distributed power source20-2is electrically connected to the utility grid30via the control device100-2. The output sides of the distributed power sources20-1and20-2are electrically connected at a linkage point32. The numbers and types of the distributed power sources20-1and20-2are not limited to those shown inFIG.1.

The control devices100-1and100-2respectively control the distributed power sources20-1and20-2. The control device100supplies power generated by the distributed power source20to the linkage point32. The input side of the control device100-1is connected to the distributed power source20-1. The control device100-1may be a power conversion device for converting the power generated by the distributed power source20-1into power corresponding to the utility grid30. The input side of the control device100-2is connected to the distributed power source20-2. The control device100-2may be a power conversion device for converting the power generated by the distributed power source20-2into power corresponding to the utility grid30. The control device100may include a device referred to as a power conditioner, a PCS (power conditioning system), or an inverter.

The output side of the control device100-1is connected to the utility grid30via the linkage point32. A transformer may be connected between the control device100-1and the linkage point32. The output side of the control device100-2may also be connected to the utility grid30via the linkage point32. The utility grid30includes a system power source34and a load36.

The control devices100-1and100-2are set with an allowable range of reactive and active powers output at normal times. The control devices100-1and100-2output the reactive power out of the allowable range, when an excess output command indicating that the reactive power exceeding the allowable range should be output, is received from a command device or the like of the power company in the utility grid30. The configuration of the control devices100-1and100-2will be described below.

The consideration calculation device200-1detects a power amount of the reactive power supplied to the utility grid30by the control device100-1. The consideration calculation device200-1calculates, based on the power amount of the reactive power, a consideration paid to an administrator of the control device100-1. Likewise, the consideration calculation device200-2detects a power amount of the reactive power supplied to the utility grid30by the control device100-2. The consideration calculation device200-2calculates, based on the power amount of the reactive power, a consideration paid to an administrator of the control device100-2. Note that the consideration calculation device200-1is not limited to this case. The consideration calculation device200-1may obtain, from an external device, the power amount of the reactive power supplied to the utility grid30by the control device100-1. Likewise, the consideration calculation device200-2may obtain, from an external device, the power amount of the reactive power supplied to the utility grid30by the control device100-2.

The consideration calculation device200-1may be provided inside the control device100-1, or may be communicatively connected with the control device100-1as a device different from the control device100-1. The consideration calculation device200-2may be provided inside the control device100-2, or may be communicatively connected with the control device100-2as a device different from the control device100-2. Moreover, the consideration calculation devices200-1and200-2may be devices provided in the utility grid30managed by the power company. The configuration of the consideration calculation devices200-1and200-2will be described below.

FIG.2shows a control device100according to one embodiment of the present invention. The control device100includes a power conditioner102, a setting unit110, an output control unit120, and a reception unit130. The power conditioner102receives power from the distributed power source20, and outputs power to the utility grid30. The power conditioner102is also referred to as an inverter.

The setting unit110is a range setting unit where an allowable range of the reactive and active powers output by the control device100at normal times is set. The output control unit120controls the reactive and active powers supplied from the distributed power source20to the utility grid30within the allowable range set in the setting unit110. The reception unit130receives, from the command device in the utility grid30, the excess output command indicating that the reactive power exceeding the allowable range should be output. The command device in the utility grid30may be a control device for controlling the utility grid30, or may be a terminal device of the administrator managing the utility grid. The reception unit130may directly receive the excess output command from the command device, or may receive the excess output command via other notification device or the like.

The output control unit120outputs the reactive power out of the allowable range when the reception unit130receives the excess output command. Specifically, the output control unit120controls the power conditioner to output the reactive power out of the allowable range when the reception unit130receives the excess output command.

In general, maximum output power of the distributed power source20such as a solar power generation device is set to be larger than maximum power (capacity) that can be output by the power conditioner102. In consideration of that a situation where the solar power generation device cannot generate the maximum output power due to weather or the like, continues for a long period of time, use of the solar power generation device around the maximum power of the power conditioner102can improve economic efficiency. However, in this embodiment, in order to secure power capacity of the reactive power output from the power conditioner102, maximum power that can be output by the power conditioner102may be larger than maximum power that can be output by the distributed power source20.

FIG.3shows an example of control contents of the reactive and active powers by the control device. A circle shown in theFIG.3shows maximum power of apparent power that can be supplied to the utility grid30by the control device100. The apparent power is represented by a vector sum of the active and reactive powers. The vertical axis inFIG.3indicates the reactive power Q (Var), and the horizontal axis therein indicates the active power P (W). The maximum power of the apparent power that can be supplied to the utility grid30by the control device100is determined by, for example, semiconductor switch capacity of the power conditioner102and the thickness of wiring.

The hatched area indicates an allowable range S of the reactive and active powers output by the control device100at normal times. As shown inFIG.3, a power factor range of the reactive and active powers may be set as the allowable range S. InFIG.3, the allowable range is determined to be in a range where the power factor is a or more and 1 or less. For example, α is a predetermined value. α may be 0.7 or more and 0.9 or less, or may be 0.8. The power factor is the ratio of the active power to the apparent power.

The output control unit120controls the reactive power Q and the active power P supplied from the distributed power source20to the utility grid within the allowable range S set in the setting unit110. InFIG.3, the reactive power is controlled to Q0as the current output. The output control unit120outputs the reactive power Qtout of the allowable range S, when the reception unit130receives, from the command device in the utility grid30, the excess output command indicating that the reactive power exceeding the allowable range S should be output.

In this example, the output control unit120outputs the reactive power Qtout of the power factor range when the reception unit130receives the excess output command. The reactive power is increased from Q0to Qt. Q0indicates the current reactive power before change, and Qtindicates the reactive power requested by the power company at the time t, that is, the reactive power instructed by the excess output command. The amount of the increased reactive power D1is |Qt−Q0|. In an example shown inFIG.3, the reactive power exceeds the allowable range S in a range of Q1or more. Excess power D2of the reactive power output exceeding the allowable range S is |Qt−Q1|.

The output control unit120increases the reactive power Q supplied to the utility grid while maintaining the active power P (referred to as Pt) supplied to the utility grid, when the reception unit130receives the excess output command. In this case, the reactive power Q1exceeding the allowable range S is expressed by the following mathematical formula. Ptis the active power maintained before and after change, and α is a power factor.

The consideration calculation device200shown inFIG.1may calculate a consideration based on a power amount (Var second) obtained by time integral (integration) of the amount of the increased reactive power D1, that is, an increased power amount (Var second) obtained by increasing power of the reactive power in response to the excess output command. When the reactive power is increased, a consumption degree of the control device100is increased accordingly. Therefore, calculation of the consideration based on the increased power amount (Var second) can compensate for the consumption of the control device100having output the reactive power.

Note that calculation of the consideration is not limited to this case. The consideration calculation device200may calculate the consideration based on a power amount (Var second) obtained by time integral (integration) of the excess power D2of the reactive power, that is, an excess power amount (Var second) of the reactive power output exceeding the allowable range in response to the excess output command. The configuration may be such that within the predetermined allowable range S, the distributed power source20(power generation device) contributes to system stabilization as its own responsibility range, while for an excess exceeding the responsibility range, the administrator of the distributed power source20receives payment of a consideration corresponding to the excess power amount (Var second).

FIG.4shows another example of control contents of the reactive and active powers by the control device. A circle shown in theFIG.4shows the maximum power of the apparent power that can be supplied to the utility grid30by the control device100. The vertical axis inFIG.4indicates the reactive power Q (Var), and the horizontal axis therein indicates the active power P (W). The hatched area indicates an allowable range S of the reactive and active powers output by the control device100at normal times. As shown inFIG.4, a power factor range of the reactive and active powers may be set as the allowable range S.

In the case shown inFIG.4, the output control unit120controls the reactive power Q0and the active power P0supplied from the distributed power source20to the utility grid30, at normal times within the allowable range S set in the setting unit110. In this example, the reception unit130receives the excess output command indicating that the reactive power exceeding the allowable range S should be output. The apparent power when the output control unit120increases the reactive power Q0to Qtin response to the excess output command (in case of the amount of the increased reactive power D1), exceeds maximum power that can be supplied to the utility grid30. The maximum power is determined by wiring capacity, output capacity of the control device (semiconductor switch capacity), and the like.

The output control unit120decreases the active power P from P0to Ptand increases the reactive power Q to Qt, when the apparent power in case of increasing the reactive power in response to the excess output command, exceeds the maximum power that can be supplied to the utility grid30. Specifically, when the excess output command commands supply of the reactive power Qt, the active power P is decreased to a value equal to or smaller than Ptwhere the straight line indicating the reactive power Qtintersects the circle indicating the maximum power of the apparent power. This allows the reactive power based on the excess output command to be supplied to the utility grid30within the maximum power of the apparent power. Therefore, voltage fluctuation of the utility grid30can be suppressed.

It should be noted that when there are a plurality of control devices100-1and100-2, as shown inFIG.3, the reactive power may be preferentially increased by the distributed power source20-1that can increase a larger amount of reactive power than the other distributed power source20-2in a range where the active power supplied to the utility grid30is not decreased.

FIG.5shows an example of an allowable range for the reactive and active powers.FIG.3andFIG.4shows the case in which a fan-shaped range where the apparent power is smaller than the maximum power value (meaning that it is inside the circle shown inFIG.3,FIG.4) and the power factor is a or more and 1 or less, is set as the allowable range S. However, the allowable range S is not limited to this case. InFIG.5, a triangle-shaped range where the power factor is a or more and 1 or less and the active power P is A or less (A is a constant predetermined to a value equal to or smaller than the maximum power of the apparent power), is set as the allowable range S.

FIG.6shows another example of an allowable range for the reactive and active powers. InFIG.6, a range (shown hatched inFIG.6) where the power factor is a or more and 1 or less, the active power P is B (note that B is a predetermined constant) or more, and the reactive power is −Qmor more and +Qm(note that Qmis a constant) or less, may be set as the allowable range S. The constant B is a constant predetermined to 0.01 or more times and 0.1 or less times the maximum power of the apparent power, for example, 0.05 times the maximum power of the apparent power. The constant Qmmay be 0.4 or more times and 0.5 or less times, for example, 0.44 times the maximum power of the apparent power. The threshold (absolute value) when the reactive power is negative may be determined to be smaller than the threshold (absolute value) when the reactive power is positive, such that −Qmis 0.25 times the maximum power of the apparent power and +Qmis 0.44 times the maximum power of the apparent power.

Even in the allowable ranges as shown inFIG.5andFIG.6, the output control unit120can increase the reactive power supplied to the utility grid30while maintaining the active power supplied to the utility grid30, when the reception unit receives the excess output command. Moreover, the output control unit120can also decrease the active power to increase the reactive power, when the apparent power in case of increasing the reactive power in response to the excess output command, exceeds the maximum power that can be supplied to the utility grid.

FIG.7shows a consideration calculation device according to one embodiment of the present invention. The consideration calculation device200may be provided in the control device100or may be provided outside the control device100. The consideration calculation device200includes a power detection unit210and a consideration calculation unit220. The power detection unit210detects a power amount of the reactive power (Var second) supplied to the utility grid30by the control device100. The power detection unit210may be a power management instrument (watthour meter). Various watthour meters can be employed as power management instruments. Note that the consideration calculation device200is not limited to this case. The consideration calculation device200may obtain from the external device the power amount of the reactive power supplied to the utility grid30by the control device100. In this case, the consideration calculation device200does not need to include the power detection unit210.

The consideration calculation unit220calculates, based on the power amount of the reactive power detected by the power detection unit210, a consideration paid to an administrator of the control device100. The consideration calculation device200may include a notification unit230. The notification unit230may notify at least one of a terminal device of a system administrator of the utility grid30and a terminal device of an administrator of the distributed power source, of the calculated consideration.

The consideration calculation unit220may obtain consideration information. The consideration calculation unit220may calculate, based on the power amount of the reactive power detected by the power detection unit210and the consideration information, the consideration paid to the administrator of the control device100. The consideration information is, for example, a price per unit of an amount of reactive power. The consideration information may be set in advance. For example, the consideration information may be determined by the power company or the like. Moreover, the consideration information may be derived by the consideration calculation unit220obtaining transaction information in a power transaction market of the active power, a power transaction market of the reactive power, or the like.

The consideration information may be set based on a consideration paid for the active power. In this case, the consideration calculation unit220calculates, further based on the consideration paid for the active power, a consideration paid for the reactive power. In an example, a unit price of the amount of reactive power may be set to be higher than a unit price of an amount of active power.

By setting the unit price of the amount of reactive power higher than the unit price of the amount of active power, the consideration paid to the administrator of the control device100is not decreased even if output of the active power is decreased in order to supply the reactive power

Moreover, a future increase in the number of the distributed power source20such as a solar power generation device will result in an increase in an amount of the active power to be supplied, and therefore there may be a surplus in the amount of active power over the amount of reactive power. It is possible to cope with such supply and demand relationship by setting the unit price of the amount of reactive power higher than the unit price of the amount of active power. Furthermore, the control device100and the distributed power source20having contributed to stabilization of the utility grid30can be highly evaluated.

The consideration calculation unit220may be provided in the utility grid30. In an example, the consideration calculation unit220may be a command device of the power company provided in the utility grid30. The power detection unit210is provided at each of the output end of the control device100-1and the output end of the control device100-2, and the consideration calculation unit220may be provided in the utility grid30. In this case, each power detection unit210and the consideration calculation unit220are communicatively connected. The consideration calculation unit220may receive a measurement result of the power amount of the reactive power from each power detection unit210.

FIG.8shows an example of a processing procedure in the power system. As shown inFIG.3toFIG.6, the setting unit110of the control device100is set with an allowable range of the reactive and active powers output at normal times. For example, the setting unit110is set with a power factor range of the reactive and active powers as the allowable range. At normal times, the output control unit120controls the reactive and active powers supplied from the distributed power source20to the utility grid30within the allowable range set in the setting unit110(step S101). When the reception unit130does not receive, from the command device in the utility grid30, the excess output command indicating that the reactive power exceeding the allowable range should be output (step S102: NO), the output control unit120continues to control the reactive and active powers within the allowable range set in the setting unit110(step S101).

When the reception unit130receives, from the command device in the utility grid30, the excess output command indicating that the reactive power exceeding the allowable range should be output (step S102: YES), the output control unit120outputs the reactive power out of the allowable range as shown inFIG.3(step S103). At this time, the output control unit120may increase the reactive power supplied to the utility grid30while maintaining the active power supplied to the utility grid30, when the reception unit130receives the excess output command. This can prevent a decrease in an acquisition consideration for the active power.

The power detection unit210in the consideration calculation device200obtains power information. The power detection unit210detects the power amount of the reactive power supplied to the utility grid30by the control device100. The consideration calculation unit220calculates, based on a detection result of the power amount from the power detection unit210, the excess power amount of the reactive power output exceeding the allowable range (step S104). The excess power amount is a power amount (Var second) obtained by time integral (integration) of the excess power D2(seeFIG.3) of the reactive power output exceeding the allowable range.

The consideration calculation unit220calculates, based on the excess power amount of the reactive power output exceeding the allowable range, a consideration paid to each administrator of the control devices100-1and100-2(step S105). The notification unit230notifies the power company of information on the calculated consideration (step S106). Specifically, the notification unit230may notify at least one of a terminal device of a system administrator of the utility grid30and a terminal device of an administrator of the distributed power source, of the calculated consideration. This allows a power producer to receive payment of a consideration from the power company (step S107). The power producer may be an administrator of the control device100.

In the processing ofFIG.8, the case is shown where the consideration is calculated, in steps S104and S105, based on the excess power amount obtained by integration of the excess power D2(seeFIG.3) of the reactive power output exceeding the allowable range S. Note that the consideration calculation unit220may calculate the consideration based on an increased power amount obtained by increasing power of the reactive power in response to the excess output command. The increased power amount is a power amount (Var second) obtained by time integral (integration) of the amount of the increased reactive power D1(seeFIG.3) obtained by increasing the reactive power in response to the excess output command.

When the reactive power is increased, a consumption degree of the control device100is increased accordingly. Therefore, calculation of the consideration based on the increased power amount (Var second) can compensate for the consumption of the control device100having output the reactive power.

FIG.9shows another example of a processing procedure in the power system. The processings of steps S201and S202are the same as processings of steps S101and S102inFIG.8. Therefore, a repeated description will be omitted.

The output control unit120determines whether the apparent power in case of increasing the reactive power in response to the excess output command, exceeds the maximum power that can be supplied to the utility grid30(step S203). When the apparent power in case of increasing the reactive power exceeds the maximum power that can be supplied to the utility grid30(step S203: YES), the active power is decreased to increase the reactive power (step S204). Specifically, as shown inFIG.4, when the excess output command commands supply of the reactive power Qt, the active power P is decreased to a value equal to or smaller than Ptwhere the straight line indicating the reactive power Qtintersects the circle indicating the maximum power of the apparent power. This allows the output control unit120to supply the reactive power based on the excess output command to the utility grid30within a range of the maximum power of the apparent power (step S205).

When the apparent power in case of increasing the reactive power does not exceed the maximum power that can be supplied to the utility grid30(step S203: NO), the output control unit120outputs the reactive power out of the allowable range (step S205). The processings of steps S205to S209are the same as processings of steps S103to S107inFIG.8. Therefore, a repeated description will be omitted.

According to the processings shown inFIG.9, the reactive power can be increased in response to the excess output command, even if the apparent power exceeds the maximum power when increasing an amount of the reactive power supplied while maintaining the active power. This can contribute to voltage stabilization of the utility grid30. In this case as well, a consideration for the amount of reactive power can be calculated based on the increased power amount (Var second) of the reactive power or the excess power amount (Var second) of the reactive power. This can compensate for the consumption of the control device100having output the reactive power, and give an incentive to the voltage stabilization of the utility grid30.

FIG.10shows another example of the power system. The power system2is added with a notification device300relative to the power system1shown inFIG.1. The power system2includes a plurality of control devices100-1and100-2, and the notification device300for notifying each of the control devices100-1and100-2of the excess output command. The number of the control devices100-1and100-2may be 3 or more.

The notification device300may be a command device, provided in the utility grid, for transmitting the excess output command indicating that the reactive power exceeding the allowable range should be output, or may be a device for totally managing a plurality of distributed power sources. For example, the notification device300may be a device of an aggregator who is an operator controlling balance between the power company and demanders, in demand response (DR) that controls an amount of demand of customers and keeps balance between demand and supply of power. When the notification device300is not the command device itself, the notification device300may receive the excess output command from the command device, and notify the control devices100-1and100-2of each of the distributed power sources20-1and20-2of the excess output command.

The notification device300may set, based on the active power supplied to the utility grid by each of the distributed power sources20-1and20-2, the reactive power to cause each of the distributed power sources20-1and20-2to output. For example, the notification device300preferentially causes the distributed power source20-1that can increase a larger amount of reactive power than the other distributed power source20-2within a range where the active power supplied to the utility grid30is not decreased, to increase the reactive power. Preferentially causing to increase the reactive power may include allocating, to the distributed power source20-1having a higher priority than the other distributed power source20-2, a larger amount of reactive power increased. A plurality of distributed power sources may be selected in a descending order of the priority to increase the reactive power such that the reactive power from each of the selected distributed power sources20is maximized (a state where the apparent power is the maximum power).

The notification device300may set the reactive power to cause each of the distributed power sources20-1and20-2to output, further based on the current reactive power. Moreover, the notification device300may set the reactive power to cause each of the distributed power sources20-1and20-2to output, further based on capacity determined by the thickness of wiring or the like. The notification device300may preferentially cause the distributed power source20with a power factor close to 1, to increase the reactive power. When the power factor is close to 1, the remaining power for increasing the reactive power is larger than when the power factor is close to 0. Alternatively, the notification device300may preferentially cause the distributed power source20-1with the current apparent power being smaller than that of the other distributed power source20-2, to increase the reactive power. Furthermore, the notification device300may preferentially cause the distributed power source20-1with a predicted value of output fluctuation caused by weather or the like being smaller than that of the other distributed power source20-2, to increase the reactive power.

The notification device300may preferentially cause the distributed power source20-1with capacity of connected electric wires being larger than that of the other distributed power source20-2, to increase the reactive power. This reduces the voltage fluctuation caused by fluctuation of the reactive power. The notification device300may preferentially cause the distributed power source20-1with the current voltage margin with respect to the voltage allowable range being larger than that of the other distributed power source20-2, to increase the reactive power.

When a plurality of distributed power sources20-1and20-2, and control devices100-1and100-2are included, it is possible to set the reactive power caused to be output from each of the distributed power sources20-1and20-2(the control devices100-1and100-2) to the utility grid30, based on the various viewpoints mentioned above.

FIG.11shows an example of computer2200where a plurality of aspects of the present invention may be entirely or partially embodied.FIG.11shows an example of hardware configuration of the computer2200that functions as the consideration calculation device200. Moreover, a plurality of computers may work together to function as the consideration calculation device200.

The computer2200according to this embodiment includes a CPU peripheral unit having a CPU2212, a RAM2214, a graphics controller2216, and a display device2218interconnected by a host controller2210; an input/output unit having a communication interface2222, a hard disk drive2224, and a DVD drive2226connected to the host controller2210by an input/output controller2220; and a legacy input/output unit having a ROM2230and an input/output chip2240connected to the input/output controller2220.

The host controller2210connects the RAM2214, and the CPU2212and the graphics controller2216that access the RAM2214at high transfer rates. The CPU2212operates based on a program stored on the ROM2230and the RAM2214, and controls each unit. The graphics controller2216obtains image data generated by the CPU2212or the like on a frame buffer provided in the RAM2214, and displays it on the display device2218. Instead, the graphics controller2216may include therein a frame buffer for storing the image data generated by the CPU2212or the like.

The input/output controller2220connects the host controller2210, and the communication interface2222, the hard disk drive2224and DVD drive2226that are relatively high speed input/output devices. The communication interface2222communicates with other devices via a network. The hard disk drive2224stores thereon a program and data to be used by the CPU2212within the computer2200. The DVD drive2226reads a program or data from a DVD-ROM2201, and provides the program or data to the hard disk drive2224via the RAM2214.

Moreover, relatively low speed input/output devices of the ROM2230and the input/output chip2240are connected to the input/output controller2220. The ROM2230stores thereon a boot-program to be executed by the computer2200at the time of start-up and/or a program dependent on the hardware of the computer2200, or the like. The input/output chip2240connects various types of input/output devices to the input/output controller2220via, for example, a parallel port, a serial port, a keyboard port for connecting a keyboard2242, a mouse port, or the like.

The program to be provided to the hard disk drive2224via the RAM2214is stored in a recording medium such as the the DVD-ROM2201or an IC card, and provided by a user. The program is read out from the recording medium, installed on the hard disk drive2224within the computer2200via the RAM2214, and executed in the CPU2212. The program is installed in the computer2200, and causes the computer2200to function as each configuration of the consideration calculation device200.

Information processing described in the program is read by the computer2200, to function as at least a part of the power detection unit210, the consideration calculation unit220, and the notification unit230which are specific means realized by cooperation between software and the various types of hardware resources, mentioned above. By realizing, with these specific means, operation or processing on information corresponding to an intended use of the computer2200in this embodiment, is constructed the consideration calculation device200that corresponds to the intended use and is specific.

As an example, if communication is performed between the computer2200and an external device or the like, the CPU2212executes a communication program loaded onto the RAM2214, and based on the processing contents described in the communication program, instructs the communication interface2222to perform communication processing. Under control of the CPU2212, the communication interface2222reads out send data memorized in a transmission buffer region or the like provided on a storage device such as the RAM2214, the hard disk drive2224, or the DVD-ROM2201to transmit the data to the network, or writes receive data received from the network into a reception buffer region or the like provided on the storage device. In this way, the communication interface2222may transfer send/receive data to/from the storage device in the DMA (direct memory access) scheme, or instead, the CPU2212may transfer send/receive data by reading out data from the storage device or the communication interface2222of a transfer source, and writing the data into the communication interface2222or the storage device of a transfer destination.

Moreover, the CPU2212causes all or necessary portions of files, databases, or the like stored in an external storage device such as the hard disk drive2224and the DVD drive2226(DVD-ROM2201) to be read into the RAM2214by the DMA transfer or the like, and performs various types of processings on the data on the RAM2214. The CPU2212writes the processed data back into the external storage device by the DMA transfer or the like. In such a processing, the RAM2214can be considered to temporarily hold contents of the external storage device, and therefore, the RAM2214, the external storage device, and the like are collectively referred to as a memory, a memory unit, a storage device, or the like in this embodiment. Various types of information such as various types of programs, data, tables, databases in this embodiment are stored on such a storage device, and are subjected to information processing. It should be noted that the CPU2212can also hold a part of the RAM2214on a cache memory, and perform read and write on the cache memory. In such configuration as well, the cache memory bears a part of function of the RAM2214, and therefore, the cache memory is also considered to be included in the RAM2214, a memory, and/or a storage device in this embodiment, unless shown distinguished.

Moreover, the CPU2212performs, on data read out from the RAM2214, various types of processings including various types of operations, information processing, conditional judgement, information search/replacement, or the like described in this embodiment that are specified in an instruction sequence of a program, and writes the data back into the RAM2214. For example, when performing conditional judgement, the CPU2212determines whether various types of variables shown in this embodiment meet condition of such as being larger than, smaller than, equal to or larger than, equal to or smaller than, or equal to other variables or constants, and when the condition is satisfied (or when it is not satisfied), branches to a different instruction sequence or invokes a subroutine.

Moreover, the CPU2212can search information stored in files, databases, or the like within a storage device. For example, when a plurality of entries in which attribute values of a second attribute are respectively associated with attribute values of a first attribute are stored in a storage device, the CPU2212can search, from among the plurality of entries stored in the storage device, an entry whose attribute value of the first attribute matches a specified condition, and read out the attribute value of the second attribute stored in the entry, thereby obtaining the attribute value of the second attribute associated with the first attribute that meets a predetermined condition.

The programs or modules shown above may be stored in an external recording medium. The recording medium to be used may be, in addition to the DVD-ROM2201, an optical recording medium such as DVD, Blu-ray (registered trademark) or CD, a magneto-optical recording medium such as MO, a tape medium, flexible disk, a semiconductor memory such as IC card, or the like. Moreover, a storage device such as a hard disk or a RAM provided to a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and a program may be provided to the computer2200via the network.

EXPLANATION OF REFERENCES