JP5738219B2 - Output smoothing device, output smoothing method, and program - Google Patents

Description

  The present invention relates to an output smoothing device, an output smoothing method, and a program for smoothing power generated by a power generation device and outputting the smoothed power to an electric power system.

  In recent years, power generation technology using natural energy such as sunlight and wind power has advanced. Along with this, the amount of renewable energy power generation facilities such as mega solar and wind farms is increasing year by year.

  However, since natural energy fluctuates from moment to moment depending on the weather, season, etc., its power generation output (active power) also fluctuates every moment. When natural energy power generation facilities are introduced in large quantities, there are concerns that the frequency and voltage of the power system may become unstable due to fluctuations in the output of natural energy. Therefore, a technology has been developed in which a natural energy power generation facility is equipped with a power storage system composed of lithium secondary batteries, etc., and absorbs (smooths) the output fluctuation of natural energy and transmits it to the power system (for example, (See Patent Document 1). Thereby, it is expected that the power system is stably operated.

JP 2008-259357 A

By the way, in order to smooth the power output to the power system, it is necessary to provide a power conversion device that converts DC power and AC power between the secondary battery, the power generation device, and the power system. Therefore, in smoothing, it is desired to minimize the loss of power conversion by the power conversion device when charging / discharging the secondary battery.
In addition, when the method described in Patent Document 1 is used, it is possible to satisfy the demand from the power system side for the suppression of output fluctuations and reduce the charge / discharge loss, but the efficiency of the power converter is considered. Absent.

  The objective of this invention is providing the output smoothing apparatus, the output smoothing method, and program which solve the subject mentioned above.

The present invention has been made to solve the above problem, and is an output smoothing device that smoothes the power generated by the power generation device and outputs it to the power system, and measures the power generated by the power generation device. A smoothing for calculating power to be charged / discharged to a secondary battery connected to the power generation device and the power system via a power conversion device for smoothing the power generated by the generated power measurement unit and the power generation device A power calculation unit and a load factor when the power conversion device converts the power calculated by the smoothed power calculation unit is equal to or greater than a predetermined load factor threshold , and the power measured by the generated power measurement unit and the past When the amount of change from the power output to the power system is greater than or equal to a predetermined change threshold, the secondary battery is charged and discharged with the power calculated by the smoothed power calculator, and the load factor is a predetermined threshold. less than a is, and before If the amount of change between the generated power measurement unit is output to the power system in the past and the power measured power is below a predetermined change amount threshold, and a discharge control unit for stopping charging and discharging of the secondary battery It is characterized by providing.

  Further, in the present invention, when the charge / discharge control unit stops the charge / discharge of the secondary battery, the power measured by the generated power measurement unit and the power output to the power system in the past It is preferable to charge / discharge the secondary battery with the power calculated by the smoothed power calculation unit when the change amount is equal to or greater than the charge / discharge restart threshold value, which is a change amount larger than the change amount threshold value.

  In the present invention, the change amount threshold is a value less than an upper limit value of the change amount of power allowed by the power system, and the charge / discharge control unit is configured to store the power measured by the generated power measurement unit and the past. When the amount of change from the power output to the power system is equal to or greater than a predetermined change amount threshold value and less than the upper limit value, the power calculated by the smoothed power calculation unit is multiplied by a gain value less than 1. It is preferable to charge and discharge the secondary battery.

The present invention also relates to an output smoothing method for smoothing the power generated by the power generation device and outputting it to the power system, the step of measuring the power generated by the power generation device, and the power generated by the power generation device. For smoothing, calculating power to be charged / discharged to a secondary battery connected to the power generation device and a power system via a power converter, and converting the power to be charged / discharged by the power converter When the load factor at the time is equal to or greater than a predetermined load factor threshold , and when the amount of change between the power generated by the power generator and the power output to the power system in the past is equal to or greater than a predetermined threshold value , The secondary battery is charged / discharged with the power to be charged / discharged, the load factor is less than a predetermined threshold , and the amount of change between the power generated by the power generator and the power output to the power system in the past is predetermined. Change amount threshold not yet If to be characterized by having a step of stopping the charging and discharging of the secondary battery.

Further, the present invention provides an output smoothing device that smoothes the power generated by the power generation device and outputs it to the power system, a generated power measuring unit that measures the power generated by the power generation device, and the power generated by the power generation device. For smoothing, a smoothed power calculation unit that calculates power to be charged / discharged to a secondary battery connected to the power generation device and a power system via a power conversion device, power calculated by the smoothed power calculation unit When the load factor when converting the power by the power converter is equal to or greater than a predetermined load factor threshold , and the amount of change between the power measured by the generated power measurement unit and the power output to the power system in the past is a predetermined amount When the amount of change is equal to or greater than the threshold value, the secondary battery is charged and discharged with the power calculated by the smoothed power calculation unit, the load factor is less than a predetermined threshold value , and the power measured by the generated power measurement unit In the past the power system If the amount of change in power output to the falls below a predetermined change amount threshold is a program for functioning as a charge and discharge control unit for stopping charging and discharging of the secondary battery.

  According to this invention, when the load factor of the power converter device by the electric power which should be charged / discharged to a secondary battery for smoothing is more than a load factor threshold value, charging / discharging of a secondary battery is performed. The “load factor” is the ratio of the actual output [W] to the rated output [W] of the power converter. In general, the power conversion device has higher power conversion efficiency as the load factor is larger. Therefore, according to the present invention, when the power conversion efficiency is high, the secondary battery is smoothed by charging and discharging, and when the power conversion efficiency is low, the generated power is directly output to the power system without charging and discharging. Also, the low power conversion efficiency means that the power to be smoothed is small, that is, the amount of change from the power output to the power system in the past is small, so even if it is output to the power system without smoothing. The power fluctuation of the power system can be kept small.

It is a schematic block diagram which shows the structure of an electric power generation system provided with the output smoothing apparatus by the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the charging / discharging control apparatus by the 1st Embodiment of this invention. It is a figure which shows the relationship between the load factor of a power converter device, and power conversion efficiency.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram showing a configuration of a power generation system including an output smoothing device 100 according to the first embodiment of the present invention.
The power generation system includes an output smoothing device 100 and a power generation device 110.

The output smoothing device 100 receives the generated power and outputs the power to the power system in order to smooth the power generated by the power generation device 110.
The power generation device 110 generates power using natural energy such as mega solar and wind farm. The power generation device 110 is connected to the power system and the power conversion device 120 and supplies the generated power to the power system and the power conversion device 120.

The output smoothing device 100 includes a power conversion device 120, a secondary battery 130, and a charge / discharge control device 140.
The power conversion device 120 is connected to the power generation device 110 and the power system, converts AC power of the power system into DC power, and converts power output from the secondary battery 130 into AC power.
The secondary battery 130 charges the power converted by the power conversion device 120 into DC power, and outputs the stored power to the power conversion device 120.
The charge / discharge control device 140 controls the charge / discharge of the secondary battery 130 based on the generated power of the power generation device 110, the power conversion efficiency of the power conversion device 120, and the amount of change in the power output to the power system. Smooths the power output to the grid.

Next, the configuration of the charge / discharge control device 140 will be described.
The charge / discharge control device 140 includes an output power measurement unit 141, an output power storage unit 142, a generated power measurement unit 143, a smoothed power calculation unit 144, an efficiency information storage unit 145, a change amount calculation unit 146, a charge / discharge control unit 147, A generated power storage unit 148 is provided.
The output power measurement unit 141 measures the power output to the power system.
The output power storage unit 142 stores the output power measured by the output power measurement unit 141 for each time.
The generated power measuring unit 143 measures the power generated by the power generation device 110.
The smoothed power calculation unit 144 calculates the power to be charged / discharged from the secondary battery 130 for smoothing the generated power based on the past generated power stored in the generated power storage unit 148.
The efficiency information storage unit 145 stores the relationship between the load factor of the power conversion device 120 and the power conversion efficiency.
The change amount calculation unit 146 uses the past output power stored in the output power storage unit 142 and the power measured by the generated power measurement unit 143 to output power when charging / discharging by the charge / discharge control unit 147 is not performed. The amount of change is calculated.
The charge / discharge control unit 147 determines whether or not to charge / discharge the secondary battery 130 based on the relationship stored in the efficiency information storage unit 145 and the change amount calculated by the change amount calculation unit 146.
The generated power storage unit 148 stores the output power measured by the generated power measurement unit 143 for each time.

Next, the operation of the charge / discharge control device 140 according to the present embodiment will be described.
FIG. 2 is a flowchart showing the operation of the charge / discharge control apparatus 140 according to the first embodiment of the present invention.
First, the generated power measurement unit 143 of the charge / discharge control device 140 measures the power generated by the power generation device 110 (step S1). At this time, the generated power measurement unit 143 records the measured power in the generated power storage unit 148. Next, the smoothed power calculation unit 144 reads the past generated power stored in the generated power storage unit 148, and calculates the power to be charged / discharged in the secondary battery 130 in order to smooth the generated power (step). S2). The smoothed power calculation unit 144 calculates the power to be output by calculating the first order lag and the moving average of the past generated power, and calculates the difference between the power and the power measured by the generated power measurement unit 143. By calculating, the electric power which should charge / discharge the secondary battery 130 is calculated.

FIG. 3 is a diagram illustrating a relationship between the load factor of the power conversion device 120 and the power conversion efficiency.
Next, the charge / discharge control unit 147 calculates the load factor of the power conversion device 120 when charging / discharging the secondary battery 130 with the power calculated by the smoothed power calculation unit 144 (step S3). Note that the charge / discharge control unit 147 calculates the load factor based on the power to be charged / discharged to the secondary battery 130 calculated by the smoothed power calculation unit 144.

FIG. 3 is a diagram illustrating a relationship between the load factor of the power conversion device 120 and the power conversion efficiency.
Next, the charge / discharge control unit 147 reads the power conversion efficiency corresponding to the calculated load factor from the efficiency information storage unit 145, and whether or not the power conversion efficiency is equal to or higher than a predetermined efficiency threshold (for example, 95%). Is determined (step S4). When the charge / discharge control unit 147 determines that the power conversion efficiency is equal to or higher than the efficiency threshold (step S4: YES), the charge / discharge control unit 147 charges and discharges the secondary battery 130 with the power calculated by the smoothed power calculation unit 144 (step S5). .

  As shown in FIG. 3, the charge / discharge control unit 147 determines whether or not the power conversion efficiency corresponding to the load factor of the power conversion device 120 is equal to or higher than the efficiency threshold. This is equivalent to determining whether the rate is equal to or higher than the load rate (load rate threshold) corresponding to the power conversion efficiency indicated by the efficiency threshold.

  On the other hand, when the charge / discharge control unit 147 determines that the power conversion efficiency is less than the efficiency threshold (step S4: NO), the change amount calculation unit 146 stores the past output power stored in the output power storage unit 142, The generated power measurement unit 143 reads out the measured power and calculates the amount of change in the output power when the secondary battery 130 is not charged / discharged based on the read power (step S6).

  The charge / discharge control unit 147 has a target change amount (change amount threshold value: for example, the change amount calculated by the change amount calculation unit 146 is lower than the upper limit value (for example, 5 megawatts / minute) of the output change amount allowed by the power system. It is determined whether it is 3 megawatts / minute) or more (step S7). When the charge / discharge control unit 147 determines that the change amount calculated by the change amount calculation unit 146 is equal to or greater than the target change amount (step S7: NO), the secondary battery 130 uses the power calculated by the smoothed power calculation unit 144. Is charged and discharged (step S5).

On the other hand, when it is determined that the change amount calculated by the change amount calculation unit 146 is less than the target change amount (step S7: NO), the charge / discharge control unit 147 stops charging / discharging of the secondary battery 130 (step S8). ).
And after charging / discharging the secondary battery 130 in step S5 or after stopping charging / discharging of the secondary battery 130 in step S8, the output power measurement part 141 measures the electric power output to the electric power system, The value is recorded in the output power storage unit 142 (step S9).
Thereafter, the above-described processing is executed every operation cycle of the charge / discharge control device 140.

  As described above, according to the present embodiment, the charge / discharge control device 140 has the load factor of the power conversion device 120 by the power to be charged / discharged to the secondary battery 130 for smoothing is equal to or greater than the predetermined load factor threshold. In such a case, the secondary battery 130 is charged and discharged. Thereby, the charge / discharge control device 140 performs smoothing by charging / discharging of the secondary battery 130 when the power conversion efficiency is high, and directly converts the power generated without charging / discharging to the power system when the power conversion efficiency is low. Can be output. Also, the low power conversion efficiency means that the power to be smoothed is small, that is, the amount of change from the power output to the power system in the past is small, so even if it is output to the power system without smoothing. The power fluctuation of the power system can be kept small.

Further, according to the present embodiment, the charge / discharge control device 140 charges the secondary battery 130 when the amount of change between the generated power of the power generation device 110 and the power output to the power system in the past is less than the target change amount. Stop discharging.
As a result, the secondary battery 130 is not unnecessarily charged / discharged when the upper limit value of the output variation allowed by the power system is sufficiently satisfied without smoothing. Loss can be prevented.

  In this embodiment, even if the output change amount when smoothing is not performed is less than the upper limit value of the output change amount allowed by the power system, the output change amount is equal to or greater than the target change amount, and the power When the load factor of the converter 120 is equal to or greater than the load factor threshold, the secondary battery 130 is charged / discharged. Thereby, even when the generated power suddenly rises or falls immediately after the charge / discharge is stopped, the change amount of the output power can be prevented from deviating from the upper limit value of the output change amount allowed by the power system.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to
For example, in this embodiment, although the case where the electric power which should charge / discharge the secondary battery 130 based on the generated electric power of the electric power generating apparatus 110 was demonstrated, it is not restricted to this. For example, when a load is connected in parallel to the power generation device 110, it is preferable to determine the power to be charged / discharged to the secondary battery 130 based on the power obtained by subtracting the power consumption of the load from the power generated by the power generation device 110.

  Further, in the present embodiment, the operation of the charge / discharge control device 140 in the case where one condition is given as the target change amount has been described. However, in the case where a plurality of conditions are given as the target change amount, the charge / discharge control device 140 is also charged. The discharge control device 140 operates in the same manner. Specifically, the smoothed power calculation unit 144 has a plurality of conditions (for example, a condition that the amount of change per past minute is 5 megawatts / minute, a condition that the amount of change per past 10 minutes is 4 megawatts / minute, etc.) ) Is calculated based on the past generated power for the time corresponding to (). In addition, the change amount calculation unit 146 calculates the change amount corresponding to each condition based on the past generated power for the time according to the plurality of conditions. And charge / discharge control part 147 stops charge / discharge, when a plurality of change amounts are all less than a target change amount.

  In the present embodiment, the case where the same value is used as the load factor threshold value at the time of charging and discharging has been described. However, the present invention is not limited to this, and the load factor threshold value may be different between charging and discharging. In particular, by setting the charging-side load factor threshold to be lower than the discharging-side load factor threshold, it is possible to increase the chances of charging the secondary battery 130 from the viewpoint of the operating region of the power conversion device 120. As the secondary battery 130 repeats charging and discharging, the charging rate of the secondary battery 130 gradually decreases due to the power conversion loss of the power conversion device 120. Therefore, as described above, the charge rate of the secondary battery 130 can be held at a predetermined value by performing charge / discharge control offset to the charge side.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described.
In the first embodiment, the charge / discharge control unit 147 performs charge / discharge when the change amount calculated by the change amount calculation unit 146 is equal to or greater than the target change amount, and charge / discharge when the change amount is less than the target change amount. The case where it is determined to stop is described. In the charge / discharge control device 140 according to the second embodiment, when the charge / discharge of the secondary battery 130 is stopped, the change amount calculated by the change amount calculation unit 146 is a change amount that is larger than the change amount threshold. The charging / discharging of the secondary battery 130 is restarted when the discharge restart threshold (for example, 4 megawatts / minute) or more is reached.

That is, in the determination of step S7 described above, when the secondary battery 130 is charged / discharged, the charge / discharge control unit 147 determines that the change amount calculated by the change amount calculation unit 146 is the output change amount allowed by the power system. It is determined whether or not the target change amount is lower than the upper limit value. If the target change amount is less than the target change amount, charging / discharging of the secondary battery 130 is stopped. On the other hand, when charging / discharging of the secondary battery 130 is stopped, the charge / discharge control unit 147 determines whether or not the change amount calculated by the change amount calculation unit 146 is greater than or equal to the charge / discharge restart threshold value that is larger than the target change amount. Is determined, and when it is less than the charge / discharge restart threshold, the charge / discharge of the secondary battery 130 is restarted.
Thereby, it is possible to prevent frequent switching between stop and restart of charge / discharge of the secondary battery 130.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described.
In the first embodiment, when the change amount calculated by the change amount calculation unit 146 is greater than or equal to the target change amount, the charge / discharge control unit 147 uses the power calculated by the smoothed power calculation unit 144 to The case where charging / discharging was performed was demonstrated. When the change amount calculated by the change amount calculation unit 146 is equal to or greater than the target change amount, the charge / discharge control device 140 according to the third embodiment uses the power to charge / discharge according to the difference between the change amount and the target change amount. Change.

Specifically, the charge / discharge control unit 147 specifies a gain to be multiplied by the power calculated by the smoothed power calculation unit 144 in step S5 described above. The gain is 0 when the change amount calculated by the change amount calculation unit 146 is equal to the target change amount, and when the change amount calculated by the change amount calculation unit 146 is equal to the upper limit value of the output change amount allowed by the power system. It is a value that simply increases in accordance with the change amount calculated by the change amount calculation unit 146. Then, the charge / discharge control unit 147 performs charge / discharge of the secondary battery 130 with power obtained by multiplying the power calculated by the smoothed power calculation unit 144 by the gain.
Thereby, it can control so that charging / discharging when the load factor of the power converter device 120 is low and power conversion efficiency is low can be performed as much as possible, and the further improvement of charging / discharging efficiency can be aimed at.

  The above-described charge / discharge control device 140 has a computer system therein. The operation of each processing unit described above is stored in a computer-readable recording medium in the form of a program, and the above processing is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  DESCRIPTION OF SYMBOLS 110 ... Power generation device 120 ... Power converter 130 ... Secondary battery 140 ... Charge / discharge control device 141 ... Output power measurement part 142 ... Output power storage part 143 ... Generated power measurement part 144 ... Smoothing power calculation part 145 ... Efficiency information storage Unit 146 ... change amount calculation unit 147 ... charge / discharge control unit 148 ... generated power storage unit

Claims (5)

An output smoothing device that smoothes the power generated by the power generation device and outputs it to the power system,
A generated power measuring unit for measuring the power generated by the power generation device;
A smoothing power calculation unit that calculates power to be charged and discharged to a secondary battery connected to the power generation device and a power system via a power conversion device for smoothing the power generated by the power generation device;
When the load factor when the power calculated by the smoothed power calculation unit is converted by the power converter is equal to or greater than a predetermined load factor threshold , and the power measured by the generated power measurement unit and the power system in the past When the amount of change from the output power is greater than or equal to a predetermined change amount threshold, the secondary battery is charged and discharged with the power calculated by the smoothed power calculation unit, the load factor is less than the predetermined threshold , and A charge / discharge control unit that stops charging / discharging of the secondary battery when the amount of change between the power measured by the generated power measurement unit and the power output to the power system in the past is less than a predetermined change amount threshold ; An output smoothing device comprising: When the charging / discharging control unit stops charging / discharging of the secondary battery, the amount of change between the power measured by the generated power measuring unit and the power output to the power system in the past is the amount of change. 2. The output smoothing according to claim 1 , wherein the secondary battery is charged and discharged with the power calculated by the smoothed power calculation unit when the charge and discharge restart threshold value, which is a change amount larger than the threshold value, is reached. Device. The change amount threshold is a value less than the upper limit value of the change amount of power allowed by the power system,
The charge / discharge control unit is configured to perform smoothing when a change amount between the power measured by the generated power measurement unit and the power output to the power system in the past is equal to or greater than a predetermined change amount threshold value and less than the upper limit value. The output smoothing device according to claim 1 or 2, wherein the secondary battery is charged and discharged with power obtained by multiplying the power calculated by the power calculation unit by a gain value less than 1 . An output smoothing method for smoothing the power generated by the power generation device and outputting it to the power system,
Measuring the power generated by the power generation device;
Calculating the power to be charged / discharged to a secondary battery connected to the power generation device and a power system via a power conversion device for smoothing the power generated by the power generation device;
When the load factor when converting the power to be charged / discharged by the power converter is a predetermined load factor threshold or more, and the change between the power generated by the power generator and the power output to the power system in the past When the amount is greater than or equal to a predetermined change amount threshold, the secondary battery is charged and discharged with the power to be charged and discharged, the load factor is less than the predetermined threshold , and the power generated by the power generation device And a step of stopping charging / discharging of the secondary battery when the amount of change from the power output to the power system is less than a predetermined change amount threshold . An output smoothing device that smoothes the power generated by the power generation device and outputs it to the power system,
A generated power measuring unit that measures the power generated by the power generator,
A smoothed power calculation unit that calculates power to be charged and discharged to a secondary battery connected to the power generation device and a power system via a power conversion device in order to smooth the power generated by the power generation device.
When the load factor when the power calculated by the smoothed power calculation unit is converted by the power converter is equal to or greater than a predetermined load factor threshold , and the power measured by the generated power measurement unit and the power system in the past When the amount of change from the output power is greater than or equal to a predetermined change amount threshold, the secondary battery is charged and discharged with the power calculated by the smoothed power calculation unit, the load factor is less than the predetermined threshold , and When the amount of change between the power measured by the generated power measurement unit and the power output to the power system in the past is less than a predetermined change amount threshold , the charge / discharge control unit stops charging / discharging of the secondary battery A program to make it work.

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