JP2022154175A - Power supply system - Google Patents

Abstract

To provide a power supply system capable of suppressing excessive fluctuations in reverse flow power to a power system.SOLUTION: In a power supply system, in a reverse flow control process, when the most recent specific reverse flow power in the past is smaller than a representative value that increases as the remaining amount of charge increases, the control device 7 instructs a charging/discharging device 10 to operate in a discharge mode that discharges the insufficient power corresponding to the shortage, and when the most recent specific reverse flow power in the past is greater than the representative value, the control device instructs the charging/discharging device to operate in the charge mode that charges with excess power corresponding to the excess portion.SELECTED DRAWING: Figure 1

Description

The present invention includes a charging/discharging device that is connected to a power line connected to a power system and charges and discharges power to and from the power line, and a solar power generation device that is connected to the power line. Regarding the connected power system.

The solar output power of a solar power generation device may fluctuate rapidly in a short period of time, depending on the weather, for example. When the solar output power of the solar power generation device rapidly increases or decreases in a short period of time, there is a high possibility that the reverse power flow to the power system or the power received from the power system will rapidly increase or decrease in a short period of time.

However, if a charging/discharging device is installed together, the discharging power of the charging/discharging device is increased or the charging power is decreased according to the decrease in the solar power output of the solar power generation device, or the solar power of the solar power generation device By decreasing the discharge power or increasing the charge power of the charging/discharging device in accordance with the increase in the output power, there is a possibility that the fluctuation range of the reverse power flow power to the power system can be reduced.
Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-140182) describes a technique for smoothing fluctuations in photovoltaic power by using discharge power of a storage battery.

JP 2016-140182 A

However, if the photovoltaic power generated by the photovoltaic power generation device cannot be obtained in real time, for example, if it can be obtained only for each set period, the photovoltaic power will already fluctuate when the information about the photovoltaic power is obtained. There is a possibility that Therefore, in a system that cannot acquire the photovoltaic power generated by the photovoltaic power generation device in real time, there is a possibility that the fluctuation range of the reverse power flow power to the power system becomes too large. For example, if it is detected that the photovoltaic power generated by the photovoltaic power generation device is very small, and then the charging/discharging device discharges a large amount of power, the photovoltaic power generation of the photovoltaic power generation device becomes large at that point. If so, the reverse flow power, which is the sum of the photovoltaic power generated by the photovoltaic power generation device and the discharge power of the charge/discharge device, may become extremely large.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply system capable of suppressing excessive fluctuations in reverse power flow power to a power system.

A power supply system according to the present invention for achieving the above object is characterized by a charging/discharging device connected to a power line connected to a power system for charging/discharging power to/from the power line, and a charging/discharging device connected to the power line. A power supply system in which a power load device is connected to the power line,
Of the reverse flow power assumed to be supplied from the power line to the power system when it is assumed that there is no charging power and discharging power of the charging and discharging device, specific reverse flow power originating from the solar power generation device Information about the remaining charge of the charging/discharging device is obtained every second set period, and information about the specific reverse flow power and information about the remaining charge are obtained. , a control device that performs a reverse power flow control process that issues an operation command to the charging and discharging device,
The control device, in the reverse power flow control process,
When the most recent specific reverse flow power in the past is smaller than a representative value defined by a relationship that increases as the remaining amount of charge increases, the charging/discharging device discharges the insufficient power corresponding to the shortage. give an instruction to operate in the discharge mode to
When the most recent specific reverse flow power in the past is greater than the representative value, it is configured to issue an instruction to operate in a charging mode for charging excess power corresponding to the excess.

According to the above characteristic configuration, even if the specific reverse flow power originating from the photovoltaic power generation device increases or decreases, if the specific reverse flow power is smaller than the representative value, the charging/discharging device operates in the discharge mode, and the specified When the reverse flow power is greater than the representative value, the charging/discharging device operates in charging mode. As a result, the reverse flow power supplied from the charging/discharging device and the solar power generation device to the power system becomes a value close to the representative value, and an excessively large fluctuation range is suppressed.
Furthermore, the greater the remaining charge, the larger the representative value, and the lower the remaining charge, the smaller the representative value. As the remaining amount of charge decreases, the charging/discharging device tends not to decrease the remaining amount of charge. As a result, it is possible to prevent the remaining amount of charge of the charging/discharging device from becoming too large or too small.

Another characteristic configuration of the power supply system according to the present invention is that the representative value is an average value of the specific reverse flow power included in a predetermined calculation period in the most recent past, and the larger the remaining charge, the larger the representative value. The point is that the corrected value is determined as follows.

According to the above characteristic configuration, the representative value is determined using the average value of the specific reverse flow power included in the predetermined calculation period in the most recent past, so the representative value greatly deviates from the actual specific reverse flow power. not be the value

Still another characteristic configuration of the power supply system according to the present invention is that the representative value is set so that the larger the remaining charge, the larger the representative value, and the smaller the closer the time zone including sunset time, the smaller the representative value. It is in.
Here, the representative value is the average value of the specific reverse power flow power included in a predetermined calculation period in the most recent past, and the greater the remaining charge, the greater the time period including sunset time. may be determined as a value corrected so as to become smaller as it approaches .

According to the above characteristic configuration, the larger the remaining charge, the larger the representative value, and the smaller the remaining charge, the smaller the representative value. Therefore, the greater the remaining charge, the higher the possibility that the specific reverse flow power will be smaller than the representative value, and the higher the possibility that the charge/discharge device will operate in the discharge mode. In addition, the smaller the remaining amount of charge, the higher the possibility that the specific reverse flow power will be larger than the representative value. As a result, it is possible to prevent the remaining amount of charge of the charging/discharging device from becoming too large or too small.

Further, since the photovoltaic power generated by the photovoltaic power generation device becomes zero after sunset, it is preferable that the charge remaining amount of the charge/discharge device increases before the time period including the sunset time.
In this characteristic configuration, the closer the time zone including sunset time, the smaller the representative value. charging power will be larger. In other words, the closer to the time zone including sunset, the greater the remaining charge of the charging/discharging device, and it can be expected that the opportunities to utilize the remaining charge of the charging/discharging device after sunset will increase.
Furthermore, when the representative value is determined using the average value of the specific reverse flow power included in the predetermined calculation period in the most recent past, the representative value does not deviate greatly from the actual specific reverse flow power. .

It is a figure which shows the structure of a power supply system. It is a figure explaining the content of a reverse power flow control process. It is a figure explaining the content of a reverse power flow control process. 7 is a graph showing a correction value determined according to the remaining charge; It is a figure explaining the content of a reverse power flow control process. It is a figure explaining the content of a reverse power flow control process. 7 is a graph showing a simulation result of reverse power flow power supplied from a power line to a power system; 4 is a graph showing the transition of the remaining charge of the charging/discharging device. 4 is a graph showing correction values determined according to remaining charge and time.

<First embodiment>
A power supply system according to a first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing the configuration of a power supply system. As illustrated, the power supply system includes a charging/discharging device 10 , a solar power generation device 30 and a control device 7 . In addition, the power supply system of this embodiment also includes a fuel cell device 20 . In the example shown in FIG. 1, the charging/discharging device 10 is connected to the first connection point 4 of the power line 2 connected to the power system 1, and the solar power generation device 30 is connected to the second connection point 5 of the power line 2. , the fuel cell device 20 and the power load device 3 are connected to the third connection point 6 of the power line 2 .

The charging/discharging device 10 is connected to a power line 2 connected to the power system 1 and charges/discharges power to/from the power line 2 . Specifically, the charging/discharging device 10 includes a charging/discharging unit 12, a power conversion unit 11 that adjusts the charging power to the charging/discharging unit 12 and the discharging power from the charging/discharging unit 12, and the operation of the power conversion unit 11. A charge/discharge control unit 13 for control and a storage unit 14 for storing information handled by the charge/discharge device 10 are provided. The charge/discharge unit 12 includes, for example, a storage battery. The charge/discharge control unit 13 can adjust the discharge power and charge power to the power line 2 between predetermined upper limit discharge power and upper limit charge power.

Information about the power measured by the power measurement unit 8 is also transmitted to the charge/discharge device 10 . The power measured by the power measuring unit 8 is power received from the power system 1 or reverse power flow to the power system 1 .

The solar power generation device 30 includes a solar cell unit 32, a power conversion unit 31 that converts the power generated by the solar cell unit 32 into a predetermined voltage, frequency, and phase and supplies the power to the power line 2, and the operation of the power conversion unit 31. A solar power generation control unit 33 for control and a storage unit 34 for storing information handled by the solar power generation device 30 are provided. The solar power generation control unit 33 can adjust the solar power generation power supplied to the power line 2 by controlling the operation of the power conversion unit 31 . For example, the photovoltaic power generation control unit 33 can operate the power conversion unit 31 to perform maximum power follow-up control.

The fuel cell device 20 includes a fuel cell unit 22, a power conversion unit 21 that converts the power generated by the fuel cell unit 22 into a predetermined voltage, frequency, and phase and supplies the power to the power line 2, the fuel cell unit 22, and the power conversion unit. 21, and a storage unit 24 for storing information handled by the fuel cell device 20. FIG. The fuel cell device 20 may also include a fuel reformer that generates hydrogen, which is the fuel gas for the fuel cell section 22 .

The fuel cell control unit 23 can adjust the output power from the fuel cell device 20 to the power line 2 between a predetermined upper limit output power and a predetermined lower limit output power. For example, the fuel cell control unit 23 can keep the output power of the fuel cell device 20 at the upper limit output power and operate the fuel cell device 20 continuously.

Information about the power measured by the power measuring unit 9 is also transmitted to the fuel cell device 20 . The power measured by the power measuring unit 9 is the power obtained by subtracting the output power of the fuel cell device 20 from the load power of the power load device 3, which is a residential load such as lighting equipment and air conditioners. That is, when the load power is greater than the output power of the fuel cell device 20, the sign of the power measured by the power measurement unit 9 is positive, and when the load power is less than the output power of the fuel cell device 20 , the sign of the power measured by the power measuring unit 9 is negative, and if the load power is the same as the output power of the fuel cell device 20, the power measured by the power measuring unit 9 is zero. The fuel cell control unit 23 can also cause the output power of the fuel cell device 20 to follow the load power of the power load device 3 . For example, the fuel cell control unit 23 adjusts the output power of the fuel cell device 20 so that the power measured by the power measurement unit 9 (that is, the power supplied from the power system 1) becomes zero. An operation that follows the load power of the load device 3 can be performed.

The control device 7 can perform information communication with the charging/discharging device 10 , the solar power generation device 30 and the fuel cell device 20 . In the case of this embodiment, the control device 7 transmits information about the reverse flow power P1 measured by the power measuring unit 8 and information about the discharge power P2 output from the charging/discharging device 10 to the power line 2 from the charging/discharging device 10. information about the photovoltaic power P3 output from the photovoltaic power generation device 30 to the power line 2 is obtained from the photovoltaic power generation device 30; Acquired from device 20 .

The reverse flow power P1 is derived by subtracting the supply power P4 from the sum of the discharge power P2 and the photovoltaic power P3. That is, P1=P2+P3-P4. In this embodiment, the fuel cell device 20 is operated according to the load following operation, that is, the fuel cell device 20 is operated so that the power measured by the power measurement unit 9 (that is, the power supplied from the power system 1) becomes zero. P4=0 because the operation is performed to adjust the output power of the .

The control device 7 selects the reverse flow power that is assumed to be supplied from the power line 2 to the power system 1 when it is assumed that there is no charging power and discharging power of the charging/discharging device 10. Information about the specific reverse flow power to be used is acquired (that is, derived) every first set time (for example, every minute). In this embodiment, since the solar power generation device 30 and the fuel cell device 20 are connected to the power line 2, when it is assumed that there is no charging power and discharging power of the charging/discharging device 10, the electric power from the power line 2 to the power system 1 The reverse flow power assumed to be supplied is "P3-P4". Then, when P4 is a positive value, that is, when there is no reverse flow power originating from the fuel cell device 20, the specific reverse flow power originating from the photovoltaic power generation device 30 is "P3-P4". . On the other hand, when P4 is a negative value, that is, when there is reverse flow power originating from the fuel cell device 20, the specified reverse flow power originating from the photovoltaic power generation device 30 is "P3". . Then, the control device 7 acquires information about the remaining charge of the charging/discharging device 10 every second set period, refers to the information about the specific reverse flow power and the information about the remaining charge, and causes the charging/discharging device 10 to operate. Perform reverse power flow control processing to issue commands.

Specifically, in the reverse power flow control process, if the most recent specific reverse power flow power in the past is smaller than a representative value that increases as the remaining amount of charge increases, the control device 7 controls the charge/discharge device 10 is instructed to operate in a discharge mode that discharges the insufficient power corresponding to the shortage, and if the most recent specific reverse flow power in the past is greater than the representative value, the excess power corresponding to the excess is charged. Give an instruction to operate in the charging mode.

[Discharge mode]
2 and 3 are diagrams schematically showing the case where the charge/discharge device 10 operates in the discharge mode. As illustrated, the control device 7 determines and stores specific reverse flow power originating from the photovoltaic power generation device 30 every minute. In the drawing, the specified reverse flow power originating from the photovoltaic power generation device 30 is described as "solar power generation power". Since P4=0 in the present embodiment, the specific reverse flow power originating from the photovoltaic power generation device 30 is the photovoltaic power P3. Then, the control device 7 determines the representative value at the reverse power flow control processing timing for each of the second set periods. The control device 7 sets the representative value to a value obtained by correcting the average value of the specific reverse flow power included in a predetermined calculation period (for example, 60 minutes) in the most recent past so that the larger the remaining charge, the larger the value. to decide. In FIGS. 2 and 3, the bar graph temporally preceding the timing of the reverse power flow control process is the specific reverse power flow power originating from the photovoltaic power generation device 30, and the control device 7 The average value of the specific reverse power flow is derived from the values.

FIG. 4 is a graph showing correction values determined according to the remaining charge. The control device 7 derives the representative value by subtracting the correction value from the average value of the specific reverse flow power, that is, by the calculation formula "representative value=average value of the specific reverse flow power−correction value". As shown in the figure, the correction value is determined to decrease as the remaining charge amount: SOC (state of charge) increases. That is, the larger the remaining charge, the larger the representative value. For example, the average value of the specific reverse flow power shown in FIGS. 2 and 3 is the same value, but in the case of FIG. 2, the remaining charge is large, so the correction value is small. The correction value is large. Therefore, the representative value is larger in the example shown in FIG. 2 (that is, when the remaining charge is large) than in the example shown in FIG.

Then, since the most recent specific reverse flow power indicated at time t0 is smaller than the representative value, the control device 7 operates in a discharge mode in which the charging/discharging device 10 discharges the insufficient power corresponding to the shortage. give instructions to In the case shown in FIG. 2, since the remaining charge is large, the discharge power instructed to the charging/discharging device 10 is large. On the other hand, in the case shown in FIG. 3, since the remaining charge is small, the discharge power instructed to the charging/discharging device 10 is small.

[Charging mode]
5 and 6 are diagrams schematically illustrating the case where charging/discharging device 10 operates in the charging mode. The average values of the specific reverse flow power shown in FIGS. 5 and 6 are the same value, but in the case of FIG. is big. Therefore, the representative value is larger in the example shown in FIG. 5 (that is, when the remaining charge is large) than in the example shown in FIG.

Then, since the most recent specific reverse flow power indicated at time t0 is greater than the representative value, the control device 7 operates in a charging mode in which the charging/discharging device 10 is charged with excess power corresponding to the excess. give instructions to 5 and 6 show a state in which part of the photovoltaic power generation power (specific reverse power flow power) is charged with the charging power of the charging/discharging device 10 after the reverse power flow control processing timing. In the photovoltaic power generated after the timing of the reverse power flow control process, the portion indicated by the dashed line is the power charged by the charging/discharging device 10 . In the case shown in FIG. 5, since the remaining amount of charge is large, the charging power instructed to the charging/discharging device 10 is small. On the other hand, in the case shown in FIG. 6, since the remaining amount of charge is small, the charging power instructed to the charging/discharging device 10 becomes large.

FIG. 7 is a graph showing a simulation result of reverse flow power supplied from the power line 2 to the power system 1. In FIG. In addition, in the figure, the 5-minute moving average value is shown.
Example 1 is the reverse flow power when the photovoltaic power generation device 30 and the power load device 3 are installed without the charging/discharging device 10 and the fuel cell device 20 installed. That is, in Example 1, when the photovoltaic power generated by the photovoltaic power generation device 30 is greater than the load power of the power load device 3 , the surplus power is reversely flowed to the power system 1 .
Example 2 is reverse flow power when the solar power generation device 30, the charge/discharge device 10, and the power load device 3 are installed without the fuel cell device 20 installed. In addition, when the photovoltaic power generated by the photovoltaic power generation device 30 is greater than the load power of the power load device 3, the charge/discharge device 10 charges all the surplus power, and the photovoltaic power is applied to the load. It is set so that the charging/discharging device 10 discharges all the insufficient power when it is smaller than the electric power. It should be noted that when the remaining amount of charge in the charging/discharging device 10 reaches the upper limit value, the charging of the surplus power is stopped and the surplus power is reversely flowed to the power system 1 .
Example 3 is the reverse power flow power when the control device 7 performs the reverse power flow control process described above.

As can be seen from FIG. 7, in the case of Example 1 in which the charging/discharging device 10 is not installed, the reverse flow power rapidly increases and decreases. In addition, in the case of example 2, when the remaining amount of charge of charging/discharging device 10 reaches the upper limit value before time 11:00, charging/discharging device 10 stops charging, so the reverse flow power increases rapidly. In addition, after the remaining amount of charge of charging/discharging device 10 reaches the upper limit value, charging/discharging device 10 does not charge surplus power, so the reverse flow powers of Examples 1 and 2 show similar changes. In the case of Example 3, it is preferable in that the reverse flow power does not show abrupt fluctuations throughout the day. In other words, it is possible to suppress an increase in the fluctuation range of the reverse power flow power to the power system 1 .

FIG. 8 is a graph showing changes in the remaining charge of charging/discharging device 10 in Example 2 shown in FIG. 7 and changes in the remaining charge of charging/discharging device 10 in Example 3 shown in FIG. As shown in the figure, also in Example 3, the remaining charge is a sufficiently large value, and the power supply capability from the charging/discharging device 10 is sufficiently secured.

As described above, even if the specific reverse flow power originating from the photovoltaic power generation device 30 increases or decreases, if the specific reverse flow power is smaller than the representative value, the charging/discharging device 10 operates in the discharge mode and the specific When the reverse flow power is greater than the representative value, charging/discharging device 10 operates in the charging mode. As a result, the reverse flow power supplied from the charging/discharging device 10 and the photovoltaic power generation device 30 to the power system 1 becomes a value close to the representative value, and an excessively large fluctuation range is suppressed. Furthermore, the larger the remaining charge of the charging/discharging device 10, the larger the representative value, and the smaller the remaining charging amount, the smaller the representative value. The charging/discharging device 10 operates with a tendency that the smaller the remaining charge is, the less the charge remaining is reduced. As a result, it is possible to prevent the remaining amount of charge of the charging/discharging device 10 from becoming too large or too small.

<Second embodiment>
The power supply system of the second embodiment differs from the above embodiment in the method of determining the representative value. The power supply system of the second embodiment will be described below, but the description of the same configuration as that of the above embodiment will be omitted.

In the present embodiment as well, in the reverse power flow control process, the control device 7 controls the charging/discharging device 10 when the most recent specific reverse power flow power in the past is smaller than the representative value that is determined in a relationship that increases as the remaining amount of charge increases. is instructed to operate in a discharge mode that discharges the insufficient power corresponding to the shortage, and if the most recent specific reverse flow power in the past is greater than the representative value, the excess power corresponding to the excess is charged. Give an instruction to operate in the charging mode.

In the present embodiment, the representative value is determined in such a relationship that the larger the remaining charge, the larger the representative value, and the closer the time period including the sunset time, the smaller the representative value. Specifically, the control device 7 increases the representative value as the average value of the specific reverse flow power included in the most recent past predetermined calculation period, the greater the remaining charge, and the sunset time A corrected value is determined so that it becomes smaller as the time zone that includes The control device 7 preliminarily stores a time period including sunset time. In this embodiment, the sunset time itself is used as the "time period including the sunset time".

FIG. 9 is a graph showing correction values determined according to remaining charge and time. As shown in the figure, the correction value is set to increase as the SOC (state of charge) decreases and as the time of sunset approaches. Then, if the remaining charge is the same, the period from 13:00 to sunset, which is the closest to sunset, has the largest correction value, and the period from sunset to 24:00, which is the furthest from sunset, The correction value is the smallest in the period from 0:00 to 10:00. Then, the control device 7 subtracts the correction value from the average value of the specific reverse flow power, that is, derives the representative value by the formula of "representative value=average value of the specific reverse flow power−correction value". That is, the representative value increases as the remaining charge level increases, and the representative value decreases as the sunset time approaches.

As described above, the closer to the time zone including sunset time, the smaller the representative value. Therefore, when charging/discharging device 10 operates in the discharging mode, the discharge power is small, and when charging/discharging device 10 operates in the charging mode, the representative value decreases. charging power will be larger. That is, as the time period including sunset time approaches, the remaining charge of charging/discharging device 10 increases, and it can be expected that the opportunities to utilize the remaining charging amount of charging/discharging device 10 after sunset will increase.

<Another embodiment>
<1>
Although the configuration of the power supply system has been described with specific examples in the above embodiment, the configuration can be changed as appropriate.
For example, in the above embodiment, the power system includes the fuel cell device 20 , but the power system may not include the fuel cell device 20 .

<2>
Although some examples of correction values have been shown in the above embodiment, they are described for the purpose of illustration and can be changed as appropriate. For example, FIGS. 4 and 9 illustrate examples in which the correction value is continuously determined according to the remaining charge of the charging/discharging device 10. For example, when the remaining charge is 0% or more and less than 30%, Apply correction value A, apply correction value B when the remaining charge is 30% or more and less than 60%, apply correction value C when the remaining charge is 60% or more and less than 100%, and so on. The correction value may be determined stepwise according to the remaining charge of the device 10 .

<3>
The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments unless there is a contradiction, and the configurations disclosed in this specification The embodiments are exemplifications, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used for a power supply system capable of suppressing excessive fluctuations in reverse power flow power to a power system.

1 power system 2 power line 3 power load device 7 control device 10 charge/discharge device 30 solar power generation device

Claims (4)

A charging/discharging device that is connected to a power line connected to a power system and charges and discharges power to and from the power line, a solar power generation device that is connected to the power line, and a power load device that is connected to the power line. a power system comprising:
Of the reverse flow power assumed to be supplied from the power line to the power system when it is assumed that there is no charging power and discharging power of the charging and discharging device, specific reverse flow power originating from the solar power generation device Information about the remaining charge of the charging/discharging device is obtained every second set period, and information about the specific reverse flow power and information about the remaining charge are obtained. , a control device that performs a reverse power flow control process that issues an operation command to the charging and discharging device,
The control device, in the reverse power flow control process,
When the most recent specific reverse flow power in the past is smaller than a representative value defined by a relationship that increases as the remaining charge amount increases, the charging/discharging device discharges the insufficient power corresponding to the shortage. give an instruction to operate in the discharge mode to
A power supply system configured to issue an instruction to operate in a charge mode for charging excess power corresponding to the excess when the most recent specific reverse flow power in the past is greater than the representative value. The representative value is determined as a value obtained by correcting an average value of the specific reverse flow power included in a predetermined calculation period in the most recent past so that the larger the remaining charge is, the larger the average value is. Power system as described. 2. The power supply system according to claim 1, wherein the representative value increases as the remaining charge level increases and decreases as a time period including sunset time approaches. The representative value is an average value of the specific reverse power flow power included in a predetermined calculation period in the most recent past. 4. The power supply system according to claim 3, wherein the corrected value is determined so as to be as small as possible.

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