JP2024021718A - Power generation system control device, power generation system control method, and program - Google Patents

Abstract

The present invention provides a control device for a power generation system that can suppress the occurrence of reverse power flow while improving the utilization rate of renewable energy power generation. A control device for a power generation system including a power generation device and a power storage device includes a power measurement system that measures power at a power reception point between a power line to which the power generation device and the power storage device are connected and a power grid. a charging rate acquisition unit that acquires the charging rate of the power storage device, and a charge/discharge control unit that controls charging and discharging of the power storage device based on the power receiving point and the charging rate, When the power receiving point power is less than a predetermined first threshold and the charging rate is less than a control start threshold indicating a charging rate lower than a charging rate upper limit value of the power storage device, the control unit controls the power storage. Charging power to the device is increased, and when the charging rate is equal to or higher than the control start threshold, the charging power is limited to a charging limit value corresponding to the charging rate. [Selection diagram] Figure 2

Description

The present disclosure relates to a power generation system control device, a power generation system control method, and a program.

In recent years, the introduction of renewable energy power generation has progressed. Hereinafter, photovoltaics (also referred to as PV) will be described as an example of renewable energy power generation. When surplus power is generated from PV, output control such as stopping PV output is performed to avoid reverse power flow to the power grid. This avoids reverse power flow to the power grid, but reduces the PV utilization rate. Therefore, by installing a battery energy storage system (also referred to as BESS) using storage batteries, the excess power of PV is charged to BESS, and later discharged from BESS to the load. The idea is to improve the rate. For example, Patent Document 1 states that when the PV output (generated power) is larger than the power consumption of the load, the BESS state of charge (hereinafter also referred to as BESS-SOC or simply SOC) is the upper limit threshold. A method is described in which a storage battery is charged with PV surplus power if it is below, and PV output control is performed when BESS-SOC exceeds an upper limit threshold.

Patent No. 6746935

In the conventional technology, PV output control is performed after it is detected that the BESS-SOC has reached the upper limit value, that is, after the supply (charging) of PV surplus power to the BESS is stopped. In this case, there is a time lag between stopping the supply of PV surplus power to the BESS and executing PV output control, and there is a possibility that PV surplus power temporarily flows backward into the power grid during this period.

An object of the present disclosure is to provide a power generation system control device, a power generation system control method, and a program that can suppress the occurrence of reverse power flow while improving the utilization rate of renewable energy power generation.

According to one aspect of the present disclosure, a control device is a control device for a power generation system including a power generation device and a power storage device, and is located at a power reception point between a power line to which the power generation device and the power storage device are connected and a power system. a power measurement unit that measures power at a receiving point to be delivered; a charging rate acquisition unit that acquires a charging rate of the power storage device; and a charging unit that controls charging and discharging of the power storage device based on the power at the power receiving point and the charging rate. a discharge control unit, the charging and discharging control unit is configured to control a charging rate at which the charging rate is lower than a charging rate upper limit value of the power storage device when the power receiving point becomes less than a predetermined first threshold value. When the charging rate is less than a control start threshold indicating the charging rate, the charging power to the power storage device is increased, and when the charging rate is equal to or higher than the control starting threshold, the charging power is limited to a charging limit value corresponding to the charging rate.

According to one aspect of the present disclosure, a control method is a control method for a power generation system including a power generation device and a power storage device, the control method being at a power receiving point between a power line to which the power generation device and the power storage device are connected and a power system. The method includes the steps of: measuring received power at a receiving point; acquiring a charging rate of the power storage device; and controlling charging and discharging of the power storage device based on the power receiving point and the charging rate. , the step of controlling the charging and discharging includes setting a control start threshold in which the charging rate indicates a charging rate lower than a charging rate upper limit value of the power storage device when the power receiving point power becomes less than a predetermined first threshold value. When the charging rate is less than the charging rate, the charging power to the power storage device is increased, and when the charging rate is equal to or higher than the control start threshold, the charging power is limited to a charging limit value corresponding to the charging rate.

According to one aspect of the present disclosure, a program is delivered to a control device of a power generation system including a power generation device and a power storage device at a power reception point between a power line to which the power generation device and the power storage device are connected and a power system. A program for executing the following steps: measuring power at a power receiving point, acquiring a charging rate of the power storage device, and controlling charging and discharging of the power storage device based on the power at the power receiving point and the charging rate. The step of controlling the charging and discharging includes starting control in which the charging rate indicates a charging rate lower than an upper limit value of the charging rate of the power storage device when the power receiving point becomes less than a predetermined first threshold value. When the charging rate is less than a threshold value, charging power to the power storage device is increased, and when the charging rate is equal to or higher than the control start threshold value, the charging power is limited to a charging limit value corresponding to the charging rate.

According to the above aspect, it is possible to suppress the occurrence of reverse power flow while improving the utilization rate of renewable energy power generation.

1 is a schematic diagram showing the overall configuration of a power generation system according to an embodiment. FIG. 2 is a block diagram showing a functional configuration of a control device according to an embodiment. 3 is a flowchart illustrating an example of processing of a control device according to an embodiment. FIG. 2 is a diagram illustrating a first example of power receiving point power and SOC according to an embodiment. FIG. 3 is a diagram for explaining the function of a limiter according to an embodiment. FIG. 7 is a diagram illustrating a second example of receiving point power and SOC according to an embodiment. FIG. 3 is a first diagram for explaining the effect of reverse power flow suppression processing according to an embodiment. FIG. 7 is a second diagram for explaining the effect of reverse power flow suppression processing according to an embodiment.

(Overall configuration of power generation system)
Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration of a power generation system according to an embodiment.
As shown in FIG. 1, the power generation system 1 includes a control device 10, a PV 20, a BESS 30, and a load 40. PV20, BESS30, and load 40 are connected via power line L1. Power line L1 is connected to the power system via a transformer. Further, the control device 10, PV20, and BESS30 are communicably connected to each other via a communication line L2.

The PV 20 is one aspect of the power generation device (renewable energy power generation device) in this embodiment, and is a power generation device that utilizes photovoltaic power generation (PV). Note that in other embodiments, the power generation system 1 may include other renewable energy power generation devices such as a wind power generation device instead of the PV 20.

PV20 outputs generated power to power line L1 via PCS (Power Conditioning System; power conditioner) 22 and PCS controller 23.

Under the control of the PCS controller 23, the PCS 22 converts the DC power generated by the PV 20 into AC power and outputs the AC power to the power line L1.

The PCS controller 23 controls the power output from the PV 20 to the power line L1 according to an output command received from the control device 10 via the communication line L2.

The BESS 30 is a power storage device using a storage battery 31. The BESS 30 includes a storage battery 31, a PCS 32, a PCS controller 33, and a BMS (Battery Management System) 34. The power generation system 1 according to this embodiment is assumed to have a configuration including only one BESS 30 to make the explanation easier to understand. Note that in other embodiments, the power generation system 1 may include a plurality of BESSs 30.

The PCS 32 switches charging and discharging of the storage battery 31 under the control of the PCS controller 33. The PCS 32 converts AC power supplied via the power line L1 into DC power and inputs it to the storage battery 31 during charging, and converts the DC power discharged from the storage battery 31 into AC power and inputs it to the power line L1 during discharging. Output.

The PCS controller 33 controls the PCS 32 so that the storage battery 31 is charged with electric power according to the power command value received from the control device 10 via the communication line L2, or the storage battery 31 is discharged.

The BMS 34 monitors the SOC (State of Charge; charging rate [%]) of the storage battery 31 and transmits it to the control device 10 .

The load 40 is an electrical device owned by the facility where the PV 20 and the BESS 30 are installed. The load 40 is supplied with power purchased from the power system, generated power of the PV 20, or discharged power of the BESS 30 through the power line L1.

The control device 10 controls the output of the PV 20 and controls the charging and discharging of the BESS 30.

(Functional configuration of control device)
FIG. 2 is a block diagram showing the functional configuration of a control device according to an embodiment.
As shown in FIG. 2, the control device 10 includes a processor 11, a memory 12, a storage 13, and a communication interface 14.

The processor 11 functions as an instruction acquisition section 110, a power measurement section 111, a charging rate acquisition section 112, and a control section 113 by operating according to a predetermined program.

The instruction acquisition unit 110 acquires an output control instruction that instructs to limit the output of generated power to the power grid. The output control instruction is notified by the power company that manages the power system. When the control device 10 acquires the output control instruction, it executes a "reverse power flow suppression process" that suppresses the reverse flow of PV surplus power for a period specified by the output control instruction. Furthermore, during the period when output control is not instructed, the control device 10 sells surplus power of the PV 20 or purchases power supplied to the BESS 30 and the load 40 within the scope of the contract with the electric power company. ``Normal processing'' may be performed. Note that in this embodiment, details of the reverse power flow suppression process will be mainly described.

The power measurement unit 111 measures power at a power reception point (hereinafter also referred to as power reception point power) where power is transferred between the power line L1 and the power grid. As in the example of FIG. 1, a power meter 2 is provided at the power receiving point, and the power measuring unit 111 measures the power at the power receiving point through the power meter 2.

The charging rate acquisition unit 112 acquires the SOC of the BESS 30 (storage battery 31) from the BMS 34 of the BESS 30 via the communication line L2.

The control unit 113 controls the output of the PV 20 and the charging and discharging of the BESS 30. The control section 113 includes a charge/discharge control section 1131 and an output control section 1132.

The charging/discharging control unit 1131 controls charging/discharging of the BESS 30 (storage battery 31) based on the receiving point power and SOC. At this time, the charge/discharge control unit 1131 calculates a BESS power command value that instructs the charging power or discharging power of the BESS, and transmits it to the PCS controller 33 of the BESS 30. The PCS controller 33 controls charging and discharging of the storage battery 31 based on the BESS power command value.

The output control unit 1132 controls the output of the PV 20 based on the SOC and power receiving point. At this time, the output control unit 1132 sets the PV output upper limit value and transmits it to the PCS controller 23. The PCS controller 23 controls the output of the PV 20 to be equal to or less than the PV output upper limit value.

The memory 12 has a memory area necessary for the operation of the processor 11.

The storage 13 is a so-called auxiliary storage device, and is, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like.

The communication interface 14 is an interface for transmitting and receiving various information with external devices (PCS controllers 23, 33, BMS 34, etc.).

Note that a predetermined program executed by the processor 11 of the control device 10 is stored in a computer-readable recording medium. Further, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, and the like. Alternatively, this computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program. Furthermore, this program may be for realizing some of the functions described above. Furthermore, it may be a so-called difference file (difference program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

(Processing flow of control device)
FIG. 3 is a flowchart illustrating an example of processing of a control device according to an embodiment.
Hereinafter, the flow of the reverse power flow suppression process of the control device 10 will be described in detail with reference to FIG. 3.

First, the power measuring unit 111 measures the receiving point power PS. Furthermore, the charging rate acquisition unit 112 acquires the SOC of the BESS 30 (step S1).

FIG. 4 is a diagram illustrating a first example of power receiving point power and SOC according to an embodiment.
The graph shown in FIG. 4 represents an example of a time series of the receiving point power PS and the SOC of the BESS 30.

When the receiving point power PS is a positive value (PS>0), it indicates that power is being supplied from the power grid (power is being purchased), and when it is a negative value (PS<0), This indicates that a reverse power flow to the power grid is occurring.

Further, the SOC changes between the charging rate lower limit value V2 and the charging rate upper limit value V1. The BESS 30 stops charging when the SOC increases to the charging rate upper limit value V1, and stops discharging when the SOC decreases to the charging rate lower limit value V2. The charging rate upper limit value V1 may be 100%, and the charging rate lower limit value V2 may be 0%, or values with a margin for each (for example, charging rate upper limit value V1 = 95%, charging rate lower limit value V2 = 5%). ).

The control unit 113 determines whether there is a possibility of reverse power flow (a state where PS<0) based on the measured power receiving point power PS. Specifically, the control unit 113 determines whether the receiving point power PS is less than the first threshold E (step S2). The first threshold value E is preset to a value (0+XkW) larger than 0 by a predetermined margin X so that reverse power flow (PS<0) can be suppressed.

If the receiving point power PS is less than the first threshold E (step S2; YES), the control unit 113 further determines whether the SOC is less than the control start threshold V3 (step S3). The control start threshold V3 is used to determine whether it is possible to consume (charge) PV surplus power by BESS30 or whether output control (output suppression) of PV20 is necessary in order to suppress the reverse flow of PV surplus power. , and a value lower than the charging rate upper limit value V1 (for example, 90%) is set.

If the SOC is less than the control start threshold V3 (step S4; YES), the control unit 113 sets the mode No. 1 is executed (step S4). Mode No. 1 is a mode in which the PV surplus power is used to charge the BESS 30 to suppress reverse power flow, and the output of the PV 20 is not controlled (the PV output power is not limited). Mode No. The details of 1 will be described later.

Further, when the SOC becomes equal to or higher than the control start threshold value V3 (step S3; NO), the control unit 113 further determines whether the SOC is less than the charging rate upper limit value V1 (step S5).

When the SOC is less than the charging rate upper limit value V1 (step S5; YES), the control unit 113 sets the mode No. 2 is executed (step S6). Mode No. 2 is a mode in which output control of the PV 20 is started while gradually reducing the power charged to the BESS 30. Mode No. The details of 2 will be described later.

On the other hand, when the SOC becomes fully charged (SOC=charging rate upper limit value V1) (step S5; NO), the control unit 113 selects the mode No. 3 is executed (step S7). Mode No. Processing No. 3 is a mode in which only the output control of the PV 20 is performed because charging of the PV surplus power is stopped when the BESS 30 is fully charged. Mode No. The details of 3 will be described later.

Further, returning to step S2, if the receiving point power PS is greater than or equal to the first threshold value E (step S2; NO), the control unit 113 determines whether the receiving point power PS exceeds the second threshold value F (step S8). . The second threshold value F is a threshold value for determining whether the power at the receiving point is large enough to eliminate the risk of reverse power flow, and a value (X+YkW) that is larger than the first threshold value E (XkW) by a predetermined margin Y is set in advance. Set.

If the receiving point power does not exceed the second threshold F (step S8; NO), the control unit 113 continues the process in the current mode (step S9).

On the other hand, when the power receiving point power is equal to or higher than the second threshold F (step S8; YES), the control unit 113 further determines whether the PV output upper limit value is less than the rated output power of the PV 20 (step S10).

When the PV output upper limit value is less than the rated output power of the PV 20, that is, when the output of the PV 20 is suppressed (step S10; YES), the control unit 113 sets the mode No. 4 is executed (step S11). Mode No. Mode 4 is a mode that improves the utilization rate of the PV 20 because there is no risk of reverse power flow. Mode No. The details of 4 will be described later.

Further, when the PV output upper limit value is the rated output power of the PV 20 (step S10; NO), the control unit 113 determines whether the SOC exceeds the charging rate lower limit value V2 (step S12).

If the SOC exceeds the charging rate lower limit value V2 (step S12; YES), the control unit 113 sets the mode No. 5 is executed (step S13). Mode No. 5 is a mode in which power is supplied (discharged) from the BESS 30 to the load 40 by the amount that the PV generated power has decreased. Mode No. The details of 5 will be described later.

When the SOC is less than or equal to the charging rate lower limit value V2 (step S12; NO), the control unit 113 sets the mode No. 6 is executed (step S14). Mode No. 6 is a mode in which power supply (discharge) from the BESS 30 to the load 40 is stopped. Mode No. 6 will be described in detail later.

(For details on each mode)
Below, the above mode No. 1~No. 6 will be explained in detail.

(1) Mode No. 1
Mode No. 1 is a mode in which there is a possibility of reverse power flow, and the BESS 30 is charged with PV surplus power to increase the receiving point power PS, but the output control of the PV 20 is not performed.

For example, as shown in FIG. 4, it is assumed that the PV generated power increases during the day, and the receiving point power PS (purchased power) gradually decreases in conjunction. At time t1, the power receiving point becomes less than the first threshold E (step S2; YES), and the SOC at this time is less than the control start threshold V3 (step S3; YES). In this case, the control unit 113 controls the mode No. 1 is executed (step S4). Specifically, the charge/discharge control unit 1131 of the control unit 113 calculates a BESS power command value new [kW] that specifies the charge/discharge power of the BESS 30 using the following equation (1), and transmits the calculated value to the BESS 30.

BESS power command value new=BESS power command value old-β...(1)

The BESS power command value old [kW] is the previous command value. β [kW] is a preset value. When the BESS power command value is a negative value, it becomes a charge command value, and when it is a positive value, it becomes a discharge command value. Note that when the BESS power command value is 0, charging and discharging are not performed. That is, the charge/discharge control unit 1131 calculates a BESS power command value that increases the power to be charged to the BESS 30 using the above equation (1). At this time, the charge/discharge control unit 1131 adjusts the BESS power command value using a limiter (FIG. 5) described later so that the charge command value does not exceed the rated input power of the BESS 30.

The BESS 30 (PCS controller 33 and PCS 32) controls the storage battery 31 to be charged with power according to the BESS power command value new received from the control device 10.

Further, the output control unit 1132 does not perform PV output control at this time. That is, the PV output upper limit value remains at the initial value. The initial value is, for example, the rated output power of the PV 20.

By doing this, mode No. 1, by increasing the power supplied to the BESS 30, it is possible to maximize the utilization rate of the PV 20 and suppress reverse power flow.

For example, as shown in FIG. 4, it is assumed that the power receiving point power PS becomes less than the first threshold E again at time t2, and the SOC at this time is less than the control start threshold V3 (step S2; YES, step S3; YES). In this case, the control unit 113 again selects the mode No. 1 is executed (step S4). That is, the charge/discharge control unit 1131 further decreases the BESS power command value by βkW (increases the charging command value by βkW) using the above equation (1). By doing this, as shown in Figure 4, during periods when the power generated by PV20 gradually increases, such as during the day, the charging command value can be increased in stages as long as there is room in the SOC of BESS30. , PV surplus power can be consumed by charging the BESS 30, and reverse power flow can be suppressed.

(2) Mode No. 2
Mode No. 2 is a mode in which the charging power is gradually reduced because the BESS 30 approaches the charging rate upper limit value V1, and the output upper limit value of the PV 20 is lowered accordingly.

For example, after time t1 in FIG. Assume that although the power receiving point power PS temporarily increases by executing step 1, the PV generated power further increases (the power receiving point power PS decreases). In the example of FIG. 4, at time t3, the power receiving point power PS is less than the first threshold E (step S2; YES), the SOC is more than the control start threshold V3 (step S3; NO), and less than the charging rate upper limit V1 (step S5). ;YES). In this case, the control unit 113 controls the mode No. 2 is executed (step S6). Specifically, the charge/discharge control section 1131 and the output control section 1132 of the control section 113 each perform the processing described below.

First, the charging/discharging control unit 1131 calculates a BESS power command value new [kW] that specifies the charging/discharging power of the BESS 30 using the following equation (2), and transmits the calculated value to the BESS 30.

BESS power command value new = BESS power command value old... (2)

According to equation (2), the charge/discharge control unit 1131 maintains the BESS power command value as it is. However, the charging/discharging control unit 1131 inputs the calculated BESS power command value new and SOC into the limiter (FIG. 5), and sets the BESS power command value new so that the charging command value decreases in proportion to the increase in SOC. adjust.

FIG. 5 is a diagram for explaining the function of the limiter according to one embodiment.
As shown in FIG. 5, the limiter applies a restriction such that the larger the SOC is, the smaller the charging command value [kW] is. When the SOC is less than the control start threshold V3, the limiter sets the upper limit value of the charging command value (hereinafter also referred to as charging limit value) as the rated input power of the BESS. Further, the limiter gradually decreases the charging limit value so that the charging limit value becomes 0 [kW] when the SOC is at the charging rate upper limit value V1 in the range from the control start threshold value V3 to the charging rate upper limit value V1.

For example, assume that the BESS power command value new is -10kW. When the charge limit value corresponding to the SOC is −10 kW, the limiter outputs the BESS power command value new (−10 kW) as it is because the charge command value≦the charge limit value. On the other hand, when the charge limit value corresponding to the SOC is -8kW, the charge command value>the charge limit value, so the limiter outputs the BESS power command value new (-8kW) rewritten to the charge limit value.

Mode No. In No. 2, the charge/discharge control unit 1131 sequentially monitors the SOC and updates the BESS power command value using the limiter. As a result, during a period in which the SOC is equal to or higher than the control start threshold value V3 and less than the charging rate upper limit value V1, the electric power charged to the BESS 30 gradually decreases in proportion to the increase in the SOC.

Moreover, since the charging power of the BESS 30 gradually decreases, the receiving point power PS also decreases, albeit slowly. Accordingly, the output control unit 1132 performs PV output control to suppress reverse power flow.

PV output control is control that decreases the PV output upper limit value when the receiving point power PS becomes less than the first threshold value E, and increases the PV output upper limit value when the receiving point power PS exceeds the second threshold value F. It is. Note that in other embodiments, instead of the first threshold E and the second threshold F, different threshold values for PV output control may be set.

Mode No. In step 2, the output control unit 1132 lowers the PV output upper limit value because the receiving point power PS became less than the first threshold value E at time t3. As a result, the PV generated power decreases and the receiving point power PS increases.

(3) Mode No. 3
Mode No. Process No. 3 is a mode in which the BESS 30 is fully charged and cannot be charged, and the reverse power flow is suppressed by controlling the output of the PV 20.

For example, at time t4 in FIG. 4, the SOC of the BESS 30 reaches the charging rate upper limit value V1 (step S5; NO). In this case, the control unit 113 controls the mode No. 3 is executed (step S7).

Specifically, the charge/discharge control unit 1131 of the control unit 113 sets the BESS power command value new to “0”.

Further, the output control section 1132 of the control section 113 controls the mode No. The output control of PV20 is performed in the same manner as in step 2. That is, the output control unit 1132 further reduces the PV output upper limit value.

(4) Mode No. 4
Mode No. Process No. 4 is a mode in which the utilization rate of the PV 20 is improved because the receiving point power PS is increased and the risk of reverse power flow is eliminated.

FIG. 6 is a diagram illustrating a second example of power receiving point power and SOC according to an embodiment.
For example, as shown in FIG. 6, it is assumed that the receiving point power PS (power purchase) gradually increases due to a decrease in the power generated by the PV 20, an increase in the power consumption of the load 40, etc. At time t5, the receiving point power exceeds the second threshold F (step S8; YES), and the PV output upper limit value is less than the rated output power (step S10; YES). In this case, the control unit 113 controls the mode No. 4 is executed (step S11). Specifically, the output control unit 1132 of the control unit 113 increases the PV output upper limit value and releases the output control of the PV 20. At this time, the output control unit 1132 may increase the PV output upper limit stepwise by αkW each time the receiving point power PS exceeds the second threshold F, thereby relaxing the PV output control. Thereby, the utilization rate of the power generated by the PV 20 can be improved while suppressing reverse power flow.

Also, mode No. In step 4, the charging/discharging control unit 1131 of the control unit 113 leaves the BESS power command value at 0 (no charging/discharging).

(5) Mode No. 5
Mode No. 5 is a mode in which power is supplied (discharged) from the BESS 30 to the load 40 when the PV generated power decreases.

For example, at time t6 in FIG. 6, the receiving point power exceeds the second threshold F (step S8; YES), and the PV output upper limit value has already reached the rated output power (step S10; NO). Furthermore, when the SOC is larger than the charging rate lower limit value V2, the control unit 113 controls the mode No. 5 is executed (step S13). Specifically, the charge/discharge control unit 1131 of the control unit 113 calculates the BESS power command value new [kW] using the following equation (3) and transmits it to the BESS 30.

BESS power command value new=BESS power command value old+β...(3)

As described above, when the BESS power command value is a positive value, it becomes the discharge command value. The BESS 30 (PCS controller 33 and PCS 32) controls the storage battery 31 to discharge (supply to the load 40) power according to the BESS power command value new received from the control device 10.

For example, as shown in FIG. 6, it is assumed that the receiving point power PS exceeds the second threshold F again at time t7, and the SOC at this time is larger than the charging rate lower limit value V2 (step S8; YES, step S10 ;YES). In this case, the control unit 113 again selects the mode No. 5 is executed (step S13). That is, the charge/discharge control unit 1131 further increases the BESS power command value by βkW (increases the discharge command value by βkW) using the above equation (3). By doing this, as shown in Fig. 6, when the power consumption of the load 40 further increases, the amount of electricity purchased is reduced by increasing the discharge command value in stages as long as there is a margin in the SOC of the BESS 30. can do.

(6) Mode No. 6
Mode No. 6 is a mode in which power supply (discharge) from the BESS 30 to the load 40 is stopped because the BESS 30 is completely discharged.

For example, at time t8 in FIG. 6, the SOC of BESS reaches the charging rate lower limit value V2 (step S12; NO). Then, the control unit 113 selects the mode No. Execute process 6.

Specifically, the charge/discharge control unit 1131 of the control unit 113 sets the BESS power command value new to “0”. As a result, the discharge of the BESS 30 is stopped.

(About the action of the control device)
FIG. 7 is a first diagram for explaining the effect of reverse power flow suppression processing according to one embodiment.
FIG. 8 is a second diagram for explaining the effect of the reverse power flow suppression process according to one embodiment.
The operation of the reverse power flow suppression process performed by the control device 10 of this embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 shows changes in receiving point power PS [kW], BESS power PB [kW], PV output upper limit value UL [kW], and SOC [%] due to reverse power flow suppression processing in the conventional technology. FIG. 8 shows changes in power receiving point power PS [kW], BESS power PB [kW], PV output upper limit value UL [kW], and SOC [%] due to the reverse power flow suppression process of this embodiment. BESS power PB is power input and output to BESS 30 based on the BESS power command value, and a positive value represents discharge power and a negative value represents charging power.

First, an example of reverse power flow suppression processing in the prior art will be described. In the conventional technology, when the receiving point power PS becomes less than the first threshold value E at time t11 in FIG. 7, a charging command value is transmitted to charge the PV surplus power to the BESS. Then, BESS electric power PB according to the charging command value is supplied (charged) to BESS. Further, thereafter, each time the receiving point power PS falls below the first threshold value E, the charging command value is increased in stages. Further, until BESS is fully charged, PV output control is not performed and the PV output upper limit value UL is not changed.

Further, when the BESS becomes fully charged at time t12 in FIG. 7, the supply of PV surplus power to the BESS is stopped, and the BESS power PB (PB_s1) that was being supplied to the BESS until just before rapidly decreases to 0. Then, the power for PB_s1 that has been supplied to BESS becomes surplus, and the power receiving point power PS rapidly decreases by that amount.

Further, as shown in FIG. 7, in the conventional technology, until the BESS is fully charged, the receiving point power PS can be increased by charging the BESS, so PV output control is not performed. After that, at time t12, when BESS is fully charged and it is detected that the receiving point power PS has decreased below the first threshold value E, a process is performed to lower the PV output upper limit value UL. However, a time lag as shown in FIG. 7 occurs after the receiving point power PS falls to the first threshold E until the PV output control (lowering the PV output upper limit UL) is executed. In the conventional technology, due to such a time lag, the PV output control cannot be adjusted in time to the sudden change in the receiving point power PS, and there is a possibility that the occurrence of reverse power flow cannot be suppressed as in the example shown in Fig. 7. there were.

Next, an example of reverse power flow suppression processing according to this embodiment will be described with reference to FIG. 8. First, mode No. 1~No. The effect of No. 3 will be explained.

At time t22 in FIG. 8, when the receiving point power PS becomes less than the first threshold value E and the SOC becomes less than the control start threshold value V3, the control unit 113 selects the mode No. Execute process 1. That is, the charge/discharge control unit 1131 of the control unit 113 reduces the BESS power command value by βkW (increases the charging command value by βkW) and transmits it to the BESS 30. Thereby, BESS power PB according to the charging command value is supplied to the BESS 30 from time to time. Further, thereafter, the control unit 113 increases the charging command value in stages every time the receiving point power PS falls below the first threshold value E.

Further, at time t23 in FIG. 8, when the SOC becomes equal to or higher than the control start threshold V3, the control unit 113 selects the mode No. Execute process 2. That is, the charge/discharge control section 1131 of the control section 113 uses a limiter (FIG. 5) to decrease the charge command value in proportion to the increase in SOC. In other words, the BESS power PB gradually decreases as the SOC approaches the charging rate upper limit V1, so at the timing immediately before the SOC reaches the charging rate upper limit V1, the BESS power PB_s2 of the conventional technology is 7), it is a very small value. Therefore, when the BESS 30 becomes fully charged at time t25 in FIG. 8 and the supply of power to the BESS 30 is stopped, the impact (amount of decrease) on the receiving point power PS also becomes small. Therefore, unlike the prior art, when the BESS power PB becomes 0, it is possible to suppress the sudden decrease in the power receiving point power PS and the occurrence of reverse power flow.

Furthermore, as described above, in the conventional technology, PV output control was performed after the BESS was fully charged and after the receiving point power PS fell below the first threshold E, so the PV output control was not completed in time and reversed. There was a possibility that a current might occur. On the other hand, the control unit 113 according to the present embodiment controls mode No. In process 2, PV output control is started in parallel with charging the BESS 30 with PV surplus power. That is, before the BESS 30 is fully charged (in the example of FIG. 8, at the timing when it is detected that the receiving point power PS has fallen below the first threshold value E at time t24), the process of lowering the PV output upper limit value UL is performed. . Thereby, the control unit 113 can more reliably suppress reverse power flow without being affected by time lag or the like.

Further, after the BESS 30 is fully charged at time t25 in FIG. 8, the control unit 113 selects the mode No. Execute process 3. At this time, the output control unit 1132) of the control unit 113 reduces the PV output upper limit value UL in stages if the receiving point power PS becomes less than the first threshold value E.

Next, mode No. 4~No. The effect of No. 6 will be explained. At time t26 in FIG. 8, when the receiving point power PS exceeds the second threshold F, the control unit 113 selects the mode No. Execute process 4. At this time, since there is no risk of reverse power flow, the output control unit 1132 of the control unit 113 increases the PV output upper limit value UL and relaxes (or cancels) the PV output control. Thereby, the control unit 113 can improve the utilization rate of the PV 20 during a period where there is no risk of reverse power flow.

In addition, in the period up to time t21 in FIG. 8, the receiving point power PS exceeds the second threshold F and the SOC is larger than the charging rate lower limit value V2, so the control unit 113 selects the mode No. Execute the process in step 5. That is, the charge/discharge control unit 1131 of the control unit 113 increases the BESS power command value by βkW (increases the discharge command value by βkW) and transmits it to the BESS 30. Thereby, the BESS power PB according to the discharge command value is discharged from the BESS 30 every moment and is supplied to the load 40, so that the amount of purchased power can be reduced. In other words, the PV surplus power stored in the BESS 30 can be effectively used. Further, thereafter, the control unit 113 may increase the discharge command value in stages every time the receiving point power PS falls below the second threshold F.

Thereafter, at time t21 in FIG. 8, the SOC reaches the charging rate lower limit value V2. Then, the control unit 113 selects the mode No. Execute process 6. Here, the charge/discharge control unit 1131 of the control unit 113 sets the BESS power command value to zero. Thereby, discharge from the BESS 30 is stopped, and over-discharge can be suppressed.

(effect)
As described above, the control device 10 of the power generation system 1 according to the present embodiment includes a power measurement unit that measures the power receiving point power PS transferred at the power receiving point between the power line L1 to which the PV 20 and the BESS 30 are connected and the power grid. 111, a charging rate acquisition unit 112 that acquires the SOC of the BESS 30, and a charging/discharging control unit 1131 that controls charging and discharging of the BESS based on the receiving point power PS and SOC. The charge/discharge control unit 1131 increases the charging power to the BESS 30 when the SOC is less than the control start threshold V3 when the receiving point power PS becomes less than the first threshold E, and when the SOC becomes equal to or higher than the control start threshold V3. At this time, the charging power is limited to a charging limit value according to the SOC.

By doing so, the control device 10 can charge the BESS 30 with PV surplus power when there is sufficient margin in the SOC, thereby suppressing the occurrence of reverse power flow and a decrease in the utilization rate of the PV 20. In addition, when the SOC approaches the charging rate upper limit value V1, the control device 10 gradually decreases the charging power, so that when the BESS 30 is fully charged and charging is stopped, the receiving point power PS suddenly changes (decreases). ) to suppress the occurrence of reverse power flow.

Furthermore, the control device 10 further includes an output control unit 1132 that controls the output of the PV 20 based on the SOC and the receiving point power PS.

By doing so, if the power receiving point power PS still decreases even after charging the BESS 30 with PV surplus power, the control device 10 performs PV output control to suppress the occurrence of reverse power flow. Can be done.

Further, the output control unit 1132 decreases the PV output upper limit value UL when the SOC is equal to or higher than the control start threshold value V3 and the receiving point power PS is less than the first threshold value E.

By doing so, the control device 10 can reduce the output of the PV 20 before the BESS 30 becomes fully charged, and therefore can more reliably suppress the occurrence of reverse power flow. Further, since the control device 10 does not perform PV output control when the SOC is less than the control start threshold V3 (mode No. 1), the utilization rate of the PV 20 is maximized during the period when the BESS 30 can be sufficiently charged. be able to.

Moreover, the output control unit 1132 increases the PV output upper limit value when the power receiving point power PS exceeds the second threshold value F.

By doing so, the control device 10 can cancel (relax) the PV output control when the receiving point power PS increases due to an increase in the power consumption of the load 40, for example. Thereby, the control device 10 can improve the utilization rate of the PV 20.

Further, the charge/discharge control unit 1131 increases the discharge power from the BESS 30 when the receiving point power PS exceeds the second threshold F and the PV output upper limit reaches the rated output power of the PV 20.

By doing so, the control device 10 can perform discharging from the BESS 30 when the receiving point power PS increases due to an increase in the power consumption of the load 40 or a decrease in the generated power of the PV 20, for example. The amount of electricity can be reduced. Thereby, the control device 10 can effectively utilize the PV surplus power stored in the BESS 30.

Further, the charge/discharge control unit 1131 stops discharging from the BESS 30 when the SOC reaches the charging rate lower limit value V2.

By doing so, the control device 10 can suppress overdischarge of the BESS 30 and suppress deterioration of the BESS 30.

As described above, several embodiments according to the present disclosure have been described, but all these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

<Additional notes>
The power generation system control device, power generation system control method, and program described in the above-described embodiments can be understood, for example, as follows.

(1) According to the first aspect of the present disclosure, the control device 10 is the control device 10 of the power generation system 1 including the power generation device 20 and the power storage device 30, to which the power generation device 20 and the power storage device 30 are connected. A power measurement unit 111 that measures power receiving point power transferred between the power line L1 and the power grid, a charging rate acquisition unit 112 that acquires the charging rate of the power storage device 30, and a charging/discharging control unit 1131 that controls charging/discharging of the power storage device 30, and the charging/discharging control unit 1131 controls whether the charging rate When the charging rate is less than the control start threshold V3 indicating a charging rate lower than the charging rate upper limit V1 of 30, the charging power to the power storage device 30 is increased, and when the charging rate is equal to or higher than the control starting threshold V3, the charging power is increased to the charging rate. Limit the charge to below the corresponding charging limit value.

By doing so, the control device 10 can charge the BESS 30 with PV surplus power when there is sufficient margin in the SOC, thereby suppressing the occurrence of reverse power flow and a decrease in the utilization rate of the PV 20. In addition, when the SOC approaches the charging rate upper limit value V1, the control device 10 gradually decreases the charging power, so that when the BESS 30 is fully charged and charging is stopped, the receiving point power PS suddenly changes (decreases). ) to suppress the occurrence of reverse power flow.

(2) According to the second aspect of the present disclosure, the control device 10 according to the first aspect further includes an output control unit 1132 that controls the output of the power generation device 20 based on the charging rate and the power receiving point.

By doing so, if the power receiving point power PS still decreases even after charging the BESS 30 with PV surplus power, the control device 10 performs PV output control to suppress the occurrence of reverse power flow. Can be done.

(3) According to the third aspect of the present disclosure, in the control device 10 according to the second aspect, the output control unit 1132 is configured such that the charging rate is equal to or higher than the control start threshold V3, and the receiving point power is the first threshold E. If the value is less than 1, the output upper limit value of the power generation device 20 is decreased.

By doing so, the control device 10 can reduce the output of the PV 20 before the BESS 30 becomes fully charged, and therefore can more reliably suppress the occurrence of reverse power flow. Further, since the control device 10 does not perform PV output control when the SOC is less than the control start threshold V3, the utilization rate of the PV 20 can be maximized during a period when the BESS 30 can be sufficiently charged.

(4) According to the fourth aspect of the present disclosure, in the control device 10 according to the second or third aspect, the output control unit 1132 controls the power generation when the receiving point power exceeds the predetermined second threshold F. Increase the output upper limit of the device 20.

By doing so, the control device 10 can cancel (relax) the PV output control when the receiving point power PS increases due to an increase in the power consumption of the load 40, for example. Thereby, the control device 10 can improve the utilization rate of the PV 20.

(5) According to the fifth aspect of the present disclosure, in the control device 10 according to the third or fourth aspect, the charging/discharging control unit 1131 controls the power receiving point power to exceed a predetermined second threshold F, and When the output upper limit reaches the rated output power of the power generation device 20, the discharge power from the power storage device 30 is increased.

By doing so, the control device 10 can perform discharging from the BESS 30 when the receiving point power PS increases due to an increase in the power consumption of the load 40 or a decrease in the generated power of the PV 20, for example. The amount of electricity can be reduced. Thereby, the control device 10 can effectively utilize the PV surplus power stored in the BESS 30.

(6) According to the sixth aspect of the present disclosure, in the control device 10 according to the fifth aspect, the charging/discharging control unit 1131 controls the power storage device 30 to stop discharging.

By doing so, the control device 10 can suppress overdischarge of the BESS 30 and suppress deterioration of the BESS 30.

(7) According to the seventh aspect of the present disclosure, the control method is a method for controlling the power generation system 1 including the power generation device 20 and the power storage device 30, the power line L1 to which the power generation device 20 and the power storage device 30 are connected. , a step of measuring power receiving point power transferred at the power receiving point with the power grid, a step of obtaining a charging rate of the power storage device 30, and a step of controlling charging and discharging of the power storage device 30 based on the power receiving point power and the charging rate. The step of controlling charging and discharging includes the step of controlling charging and discharging when the charging point is lower than the charging rate upper limit value V1 of the power storage device 30 when the power receiving point becomes less than a predetermined first threshold value E. When the charging rate is less than the control start threshold V3 indicating the charging rate, the charging power to the power storage device 30 is increased, and when the charging rate is equal to or higher than the control starting threshold V3, the charging power is limited to below the charging limit value corresponding to the charging rate.

(8) According to the eighth aspect of the present disclosure, the program includes a power line L1 to which the power generation device 20 and the power storage device 30 are connected to the control device 10 of the power generation system 1 including the power generation device 20 and the power storage device 30; A step of measuring the power receiving point power transferred at the power receiving point with the power grid, a step of acquiring the charging rate of the power storage device 30, and a step of controlling charging and discharging of the power storage device 30 based on the power receiving point power and the charging rate. The program executes the following, and the step of controlling charging/discharging is such that when the power receiving point becomes less than a predetermined first threshold E, the charging rate is lower than the charging rate upper limit value V1 of the power storage device 30. When the charging rate is less than the control start threshold V3 indicating a low charging rate, the charging power to the power storage device 30 is increased, and when the charging rate is equal to or higher than the control starting threshold V3, the charging power is limited to a charging limit value corresponding to the charging rate or less. .

1 Power generation system 2 Wattmeter 10 Control device 11 Processor 110 Instruction acquisition section 111 Power measurement section 112 Charging rate acquisition section 113 Control section 1131 Charge/discharge control section 1132 Output control section 12 Memory 13 Storage 14 Communication interface 20 PV (power generation device)
23 PCS controller 30 BESS (power storage device)
31 Storage battery 33 PCS controller 40 Load

Claims (8)

A control device for a power generation system including a power generation device and a power storage device,
a power measurement unit that measures power received at a power receiving point between a power line to which the power generation device and the power storage device are connected, and a power system;
a charging rate acquisition unit that acquires the charging rate of the power storage device;
a charging and discharging control unit that controls charging and discharging of the power storage device based on the power receiving point power and the charging rate;
Equipped with
The charge/discharge control unit, when the power receiving point becomes less than a predetermined first threshold,
When the charging rate is less than a control start threshold indicating a charging rate lower than a charging rate upper limit value of the power storage device, increasing charging power to the power storage device;
When the charging rate is equal to or higher than the control start threshold, the charging power is limited to a charging limit value or less according to the charging rate.
Control device for power generation system. further comprising an output control unit that controls the output of the power generation device based on the charging rate and the power receiving point;
A control device for a power generation system according to claim 1. The output control unit reduces the output upper limit value of the power generation device when the charging rate is equal to or higher than the control start threshold and the power receiving point is less than the first threshold.
A control device for a power generation system according to claim 2. The output control unit increases an output upper limit value of the power generation device when the power reception point exceeds a predetermined second threshold.
A control device for a power generation system according to claim 2. The charge/discharge control unit increases the discharge power from the power storage device when the power receiving point exceeds a predetermined second threshold and the output upper limit reaches the rated output power of the power generation device. ,
A control device for a power generation system according to claim 3 or 4. The charge/discharge control unit stops discharging from the power storage device when the charging rate reaches a lower limit of charging rate.
A control device for a power generation system according to claim 5. A method for controlling a power generation system including a power generation device and a power storage device, the method comprising:
a step of measuring power receiving point power transferred at a power receiving point between a power line to which the power generation device and the power storage device are connected and a power system;
obtaining a charging rate of the power storage device;
controlling charging and discharging of the power storage device based on the power receiving point power and the charging rate;
has
In the step of controlling the charging and discharging, when the power receiving point becomes less than a predetermined first threshold,
When the charging rate is less than a control start threshold indicating a charging rate lower than a charging rate upper limit value of the power storage device, increasing charging power to the power storage device;
When the charging rate is equal to or higher than the control start threshold, the charging power is limited to a charging limit value or less according to the charging rate.
How to control a power generation system. A control device for a power generation system that includes a power generation device and a power storage device,
a step of measuring power receiving point power transferred at a power receiving point between a power line to which the power generation device and the power storage device are connected and a power system;
obtaining a charging rate of the power storage device;
controlling charging and discharging of the power storage device based on the power receiving point power and the charging rate;
A program that executes
In the step of controlling the charging and discharging, when the power receiving point becomes less than a predetermined first threshold,
When the charging rate is less than a control start threshold indicating a charging rate lower than a charging rate upper limit value of the power storage device, increasing charging power to the power storage device;
When the charging rate is equal to or higher than the control start threshold, the charging power is limited to a charging limit value or less according to the charging rate.
program.

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