JP7789478B2 - Power generation system, control method and program - Google Patents

Description

The present invention relates to a distributed power supply system that includes a power generation mechanism such as a solar power generation system and a power storage mechanism such as a battery system, as well as a control method and program.

In recent years, distributed power generation systems that include power generation mechanisms such as solar power generation systems and power storage mechanisms such as battery systems and that are connected to commercial power grids have become increasingly common (see, for example, Patent Document 1). Consumers can, for example, convert the electricity generated by solar power generation into alternating current and supply it to loads or the connected power grid, and store surplus electricity to use during the daytime when power demand is tight, enabling peak shifting.

Japanese Patent Application Laid-Open No. 2018-125974

In a distributed power generation system, during stand-alone operation where a load operates without using power supplied from a commercial power grid, if the power generated by solar power generation or the like exceeds the load power, the surplus power is charged into a storage battery in a storage battery system or the like. In a distributed power generation system, the power converter connected to the power generation mechanism and the power converter connected to the storage mechanism are connected by a DC bus. Here, when the storage battery becomes fully charged, the power converter on the storage battery side prevents the storage battery from becoming overcharged by limiting the current flowing in the charging direction to 0 A. However, if there is current flowing in the charging direction through the DC bus, charging continues at a constant power (low power), which could cause the storage battery to become overvoltage.

The present invention was made in consideration of the above circumstances, and its purpose is to provide technology that prevents overcharging of a storage battery during stand-alone operation of a distributed power generation system equipped with a power generation mechanism and a power storage mechanism.

One aspect of the disclosed technology for solving the above problem is:
A power supply system including a power generation device, a storage battery, and a power converter capable of independent operation that supplies power to a load of a consumer based on DC power supplied to a power bus from at least one of the power generation device and the storage battery, the power supply system being operated in connection with a power grid of the consumer,
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command related to maximum power point tracking control from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
When the amount of power generated by the power generation device exceeds the amount of load power consumed by the load and the state of charge of the storage battery satisfies a predetermined condition during the independent operation, the control unit maintains a target value in the maximum power point tracking control before the state of charge of the storage battery satisfies the predetermined condition as a control command to the first power conversion unit, and
a gate block instruction for stopping the charge/discharge control as a charge/discharge control command to the second power conversion unit, and cutting off the DC power supplied from the power bus;
It is characterized by:

As a result, in the power supply system, when the state of charge of the storage battery unit 23, which is a storage battery, satisfies a predetermined condition, the bidirectional DC/DC converter 24, which is the second power conversion unit, can be controlled to cut off the DC power supplied in the charging direction from the DC bus 25, which is the power bus. The DC/DC converter 22, which is the first power conversion unit, can be controlled so that the DC bus 25 is supplied with DC power generated by the photovoltaic power generation module 21, which is the power generation device, just as before the full charge state. Because the power supply system can cut off the DC power supplied in the charging direction from the DC bus 25, it is possible to reliably prevent overcharging of the storage battery due to minute power flowing in the charging direction through the DC bus 25 during standalone operation. Because the DC bus 25 can be supplied with DC power generated by the photovoltaic power generation module 21 just as before the full charge state, standalone operation can be continued, in which power is supplied to the load 70 based on the generated power.

In one embodiment of the disclosed technology, the control unit may detect a voltage drop in the DC power supplied to the power bus and issue a charge/discharge control command to the second power conversion unit to release a gate block instruction that stops the charge/discharge control and supply the stored power charged in the storage battery to the power bus. This allows the control unit 11 to release the gate block in response to a voltage drop in the DC voltage supplied to the DC bus 25, and supply DC power based on the stored power stored in the storage battery unit 23 to the DC bus 25. This enables more precise power assistance based on stored power in response to fluctuations in the power consumed by the load 70 and fluctuations in the power generated by the solar cell module 21, etc.

Furthermore, in one form of the disclosed technology, the control unit may issue, as a charge/discharge control command to the second power conversion unit, a second voltage value that is lower than a first voltage value that is the target value for the maximum power point tracking control for the first power conversion unit, as a target voltage for canceling a gate block instruction that stops the charge/discharge control and starting the supply of DC power based on the stored power charged in the storage battery to the power bus.

As a result, the second voltage value in the discharge direction instructed to the bidirectional DC/DC converter 24 is lower than the first voltage value, which is the control target value of the DC/DC converter 22 that continues MPPT control. Therefore, provided that the voltage value of the power supplied to the DC bus 25 falls below the second voltage value, the gate block is released and the power stored in the power storage unit 23 can be discharged and supplied to the DC bus 25. Even if the load power cannot be supplied solely with the DC power generated by the solar power generation module 21, causing a voltage drop on the DC bus 25, the power supply system can start discharging control of the bidirectional DC/DC converter 24 when the voltage value of the DC bus 25 falls below the second voltage value. Therefore, the gate block of the bidirectional DC/DC converter 24 can be released in response to fluctuations in the power consumed by the load 70 and fluctuations in the power generated by the solar power generation module 21, etc., making it possible to supplement the amount of power using stored power.

Furthermore, another aspect of the disclosed technology is:
A control method executed by a power converter of a power supply system that includes a power generation device, a storage battery, and a power converter capable of independent operation that supplies power to a load of a consumer on the basis of DC power supplied to a power bus from at least one of the power generation device and the storage battery, the power converter being interconnected to a power grid of the consumer, the control method comprising:
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command related to maximum power point tracking control from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
When the amount of power generated by the power generation device exceeds the amount of load power consumed by the load and the state of charge of the storage battery satisfies a predetermined condition during the independent operation, the control unit maintains a target value in the maximum power point tracking control before the state of charge of the storage battery satisfies the predetermined condition as a control command to the first power conversion unit, and
a gate block instruction for stopping the charge/discharge control as a charge/discharge control command to the second power conversion unit, and cutting off the DC power supplied from the power bus;
Do this.

Even in this configuration, when a predetermined condition for the storage battery unit 23, which is a storage battery, is met, the power supply system can control the bidirectional DC/DC converter 24, which is the second power conversion unit, to cut off the DC power supplied to the DC bus 25, which is a power bus, in the charging direction from the DC bus 25. The DC/DC converter 22, which is the first power conversion unit, can be controlled so that the DC bus 25 is supplied with DC power generated by the photovoltaic power generation module 21, which is a power generation device, just as before the fully charged state. Because the power supply system can cut off the DC power supplied in the charging direction from the DC bus 25, it is possible to reliably prevent overcharging of the storage battery due to minute power flowing in the charging direction through the DC bus 25 during standalone operation. Because the DC bus 25 can be supplied with DC power generated by the photovoltaic power generation module 21 just as before the fully charged state, standalone operation can be continued, in which power is supplied to the load 70 based on the generated power.

Furthermore, another aspect of the disclosed technology is:
a power converter capable of independent operation that supplies power to a load of a consumer based on DC power supplied to a power bus from at least one of the power generation device and the storage battery; and a program to be executed by the power converter of a power supply system that is operated in connection with a power grid of the consumer, the program comprising:
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command related to maximum power point tracking control from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
When the amount of power generated by the power generation device exceeds the amount of load power consumed by the load and the state of charge of the storage battery satisfies a predetermined condition during the independent operation, the control unit maintains, as a control command to the first power conversion unit, a target value in the maximum power point tracking control that was set before the state of charge of the storage battery satisfied the predetermined condition; and
a gate block instruction for stopping the charge/discharge control as a charge/discharge control command to the second power conversion unit, and cutting off the DC power supplied from the power bus;
Make it happen.

Even in this configuration, when the state of charge of the storage battery unit 23, which is a storage battery, satisfies a predetermined condition, the power supply system can control the bidirectional DC/DC converter 24, which is a second power conversion unit, to cut off DC power supplied to the DC bus 25, which is a power bus, in the charging direction from the DC bus 25. The DC/DC converter 22, which is a first power conversion unit, can be controlled so that DC power generated by the photovoltaic power generation module 21, which is a power generation device, is supplied to the DC bus 25, just as it was before the full charge state. Because the power supply system can cut off DC power supplied in the charging direction from the DC bus 25, it is possible to reliably prevent overcharging of the storage battery due to minute power flowing in the charging direction through the DC bus 25 during stand-alone operation. Because DC power generated by the photovoltaic power generation module 21 can be supplied to the DC bus 25, just as it was before the full charge state, stand-alone operation can be continued, in which power is supplied to the load 70, which is a load, based on the generated power.

The present invention makes it possible to prevent overcharging of a storage battery during stand-alone operation of a distributed power generation system equipped with a power generation mechanism and a power storage mechanism.

1 is a block diagram showing a schematic configuration of a distributed power supply system according to a first embodiment of the present invention; FIG. 2 is an explanatory diagram illustrating the flow of power during independent operation in the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a control operation during independent operation in the first embodiment of the present invention. FIG. 4 is an explanatory diagram illustrating overcharging of the storage battery unit due to minute power in the first embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating a control operation of the distributed power generation system according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a voltage value of DC power supplied to a DC bus in the first embodiment of the present invention. 4 is a time chart showing the progress of the control operation of the distributed power generation system according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit according to the first embodiment of the present invention. 4 is a flowchart showing an example of an overcharge prevention process in the first embodiment of the present invention.

[Application example]
Hereinafter, application examples of the present invention will be described with reference to the drawings.
Fig. 1 is a block diagram showing a schematic configuration of a distributed power system 20 according to an application example of the present invention. Fig. 1 illustrates a distributed power system 20 that is interconnected with a commercial power grid 80 installed on a consumer's premises and supplies AC power to a load 70 and the interconnected power grid 80. The distributed power system 20 according to the application example of the present invention is a hybrid power system that includes a photovoltaic power generation system as a power generation mechanism and a storage battery system as a power storage mechanism.

As shown in FIG. 1, the distributed power system 20 includes a solar power generation module 21, a storage battery unit 23, and a power conditioner (hereinafter also referred to as "PCS") 10. The PCS 10 includes a power conversion unit 12, a control unit 11, a DC/DC converter 22, and a bidirectional DC/DC converter 24. The DC/DC converter 22 of the PCS 10 is connected to the solar power generation module 21. The bidirectional DC/DC converter 24 of the PCS 10 is connected to the storage battery unit 23. The DC/DC converter 22 and the bidirectional DC/DC converter 24 are connected by a DC bus 25. The power conversion unit 12 of the PCS 10 is connected to the DC bus 25 and converts DC power supplied through the DC bus into AC power synchronized with the power grid 80, and also converts AC power supplied from the power grid 80 into DC power and outputs it to the DC bus 25.

The control unit 11 of the PCS 10 receives outputs from various sensors, including a power sensor 26 (current sensor, voltage sensor) provided on the DC bus 25, a power sensor 27 (current sensor, voltage sensor) provided between the photovoltaic power generation module 21 and the DC/DC converter 22, and a wattmeter 81 provided on a power line 83 connecting the distribution board 82 and the power grid 80. Based on information detected by the various sensors, the control unit 11 performs maximum power point tracking (MPPT) control so that the DC/DC converter 22 operates at the maximum power (value of current x voltage) point where the power output of the photovoltaic power generation module 21 is maximized or at the optimal operating point. The control unit 11 performs charge/discharge control processing based on the load conditions detected by the various sensors and preset charge/discharge modes.

In the distributed power supply system 20 according to the application example, as shown in Figures 2 and 3, when autonomous operation is performed, power generated by the photovoltaic power generation modules 21 and the like is supplied to the DC bus 25 via the DC/DC converter 22. Furthermore, when the power generated by the photovoltaic power generation modules 21 and the like exceeds the load power, the surplus power exceeding the load power is charged to the storage battery unit 23 via the bidirectional DC/DC converter 24. Here, as shown in Figure 4, if a certain amount of power (micropower) in the direction of charging the storage battery unit 23 occurs between the current command value (BATI limit command value) to the bidirectional DC/DC converter 24 and the actual current value (BATI), this micropower current will flow into the storage battery unit 23, potentially causing an overvoltage state in the storage battery.

In the distributed power system 20 according to the application example, as shown in Figures 5 to 9, when the charge rate of the storage battery unit 23 satisfies a predetermined condition, the bidirectional DC/DC converter 24 and the DC/DC converter 22 are controlled to prioritize power generated by the photovoltaic power generation module 21 and other devices and output it to the DC bus 25. Specifically, the DC power in the charging direction supplied from the DC bus 25 to the storage battery unit 23 is blocked by gate block processing, and the DC power supplied from the photovoltaic power generation module 21 to the DC bus 25 is prioritized and supplied to the load 70. Furthermore, the DC bus voltage command value in the discharging direction for the bidirectional DC/DC converter 24 is set lower than the DC bus voltage command value for the DC/DC converter 22. Here, the predetermined condition is a threshold value for the charge rate used to determine the charge state of the storage battery unit 23, and is set in advance based on the size and configuration of the distributed power system 20, the storage capacity of the storage battery unit 23, the load power supplied to the load 70 during autonomous operation, etc. An example of a predetermined condition is when the storage battery unit 23 is fully charged. By performing such control processing, the distributed power system 20 according to the application example can prevent overcharging of the storage battery due to minute amounts of power flowing in the charging direction through the DC bus 25 during independent operation.

Example 1
Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

<System Configuration>
FIG. 1 is a block diagram showing a schematic configuration of a distributed power system 20 according to an embodiment of the present invention. The distributed power system 20 in this embodiment is a hybrid power system including a solar power generation system as a power generation mechanism and a battery system as a power storage mechanism. As shown in FIG. 1 , the distributed power system 20 constitutes a power supply system 1 that is interconnected with a commercial power grid 80 installed on a consumer's premises and supplies AC power to a load 70 and the interconnected power grid 80. The distributed power system 20 is connected to the commercial power grid 80 and the load 70 via a distribution panel 82. While this embodiment will be described using a solar power generation system as a power generation mechanism, the distributed power system 20 may employ other types of power generation systems besides a solar power generation system. Examples of other types of power generation systems include power generation systems that use natural energy, such as wind power or hydropower, and private power generation systems that use fuel.

The distributed power system 20 of this embodiment includes a solar power generation module 21, a storage battery unit 23, and a power conditioner (hereinafter also referred to as "PCS") 10. In this embodiment, the power conditioner 10 corresponds to an example of a "power converter." The PCS 10 includes a power conversion unit 12, a control unit 11, a DC/DC converter 22, and a bidirectional DC/DC converter 24. The DC/DC converter 22 of the PCS 10 is connected to the solar power generation module 21 that constitutes the power generation mechanism. The bidirectional DC/DC converter 24 of the PCS 10 is connected to the storage battery unit 23 that constitutes the power storage mechanism. In the distributed power system 20 of this embodiment, the PCS 10 and the solar power generation module 21 constitute a solar power generation system, and the PCS 10 and the storage battery unit 23 constitute a storage battery system. The distributed power system 20 of this embodiment corresponds to a "power supply system."

The DC/DC converter 22 and bidirectional DC/DC converter 24 of the PCS 10 in this embodiment are connected by a DC bus 25. The power conversion unit 12 of the PCS 10 is connected to the DC bus 25 and converts DC power supplied through the DC bus into AC power. The power conversion unit 12 includes a DC/AC converter that converts DC power supplied through the DC bus 25 into AC power synchronized with the power grid 80, and an AC/DC converter that converts AC power supplied from the power grid 80 into DC power and outputs it to the DC bus 25. In this embodiment, the solar power generation module 21 constituting the power generation mechanism is an example of a "power generation device," and the storage battery unit 23 constituting the power storage mechanism is an example of a "storage battery." The DC/DC converter 22 provided in the power conditioner (PCS) 10 in this embodiment corresponds to the "first power conversion unit," and the bidirectional DC/DC converter 24 corresponds to the "second power conversion unit." Furthermore, the DC bus 25 to which the DC/DC converter 22 and the bidirectional DC/DC converter 24 in this embodiment are connected corresponds to the "power bus."

The DC/DC converter 22 is a unit that boosts the DC power generated by the solar power generation module 21 and supplies it to the DC bus 25. The storage battery unit 23 is a storage battery that stores a predetermined amount of power determined by its rating, etc., and the number of times it can be charged and discharged is limited by this rating, etc. The bidirectional DC/DC converter 24 is a unit that bidirectionally converts the voltage of the power supplied via the DC bus 25 to charge the storage battery unit 23, and the voltage of the discharged power output from the storage battery unit 23 to the DC bus 25. The DC/DC converter 22, storage battery unit 23, and bidirectional DC/DC converter 24 each incorporate a microcomputer or the like that operates in response to control commands from the control unit 11.

The control unit 11 of the PCS 10 is a unit comprising a processor (e.g., CPU), memory, gate drivers, a communication interface circuit, etc. The control unit 11 receives outputs from various sensors, including a power sensor 26 (current sensor, voltage sensor) provided on the DC bus 25, a power sensor 27 (current sensor, voltage sensor) provided between the solar power generation module 21 and the DC/DC converter 22, and a power meter 81 provided on the power line 83 connecting the distribution board 82 and the power grid 80. Based on the information detected by the various sensors, the control unit 11 performs maximum power point tracking (MPPT) so that the DC/DC converter 22 operates at the maximum power (value of current x voltage) point where the power output of the solar power generation module 21 is at its maximum or optimal operating point.

The control unit 11 also performs control processing related to charging and discharging (also referred to as power storage control processing) based on the load conditions detected by the various sensors described above and preset charging and discharging modes. For example, when discharging, the control unit 11 controls the bidirectional DC/DC converter 24 to convert the power discharged from the storage battery unit 23 and supply it to the DC bus 25, and when discharging is to be stopped, the control unit 11 controls the storage battery unit 23 to stop discharging and stop the power being discharged to the DC bus 25.

Furthermore, when the control unit 11 determines that charging should be performed based on the above mode, load conditions, the charging state of the storage battery unit 23, etc., it converts the power of the photovoltaic power generation module 21 supplied to the DC bus 25 via the power grid 80 and the DC/DC converter 22 and controls the power to be charged to the storage battery unit 23. The operation of the storage battery unit 23 and the bidirectional DC/DC converter 24 is controlled in response to control commands related to the above power storage control process from the control unit 11.

Figure 2 is an explanatory diagram illustrating the flow of power during autonomous operation. In the distributed power system 20, during autonomous operation, as indicated by the diagonally hatched arrow A1, power generated by the solar power generation modules 21 and the like is supplied to the DC bus 25 via the DC/DC converter 22. The DC/DC converter 22 performs MPPT control based on control commands from the control unit 11, converts the power generated by the solar power generation modules 21 and the like to a predetermined voltage value, and outputs it to the DC bus 25. The power conversion unit 12 of the PCS 10 connected to the DC bus 25 converts the DC power supplied to the DC bus 25 to AC power synchronized with the power grid 80 based on control commands from the control unit 11, and supplies it to the load 70 (output voltage control (OUTV control), output current control (OUTI control)). Furthermore, if the power generated by the solar power generation modules 21 and the like exceeds the load power, the surplus power exceeding the load power is charged to the storage battery unit 23 via the bidirectional DC/DC converter 24. The bidirectional DC/DC converter 24 performs DC bus voltage control (BATI control) based on control commands from the control unit 11, converts the voltage of the DC power supplied to the DC bus 25, and charges the storage battery unit 23.

Figure 3 is an explanatory diagram illustrating control operations during autonomous operation. Figure 3 illustrates the control form of the DC/DC converter 22 (also called a unidirectional DD) in response to the DC bus voltage detected via the power sensor 26 (current sensor, voltage sensor). As shown in Figure 3, during autonomous operation, the DC/DC converter 22 performs MPPT control based on a control command (DC bus voltage command value) from the control unit 11, boosting the power generated by the photovoltaic power generation module 21, etc., to a predetermined voltage value and outputting it to the DC bus 25. When the DC bus voltage detected via the power sensor 26 (current sensor, voltage sensor) exceeds the predetermined value A2, the control unit 11 controls the DC/DC converter 22 to suppress an increase in the DC bus voltage. By suppressing the increase in the DC bus voltage, the voltage value of the DC power supplied from the DC/DC converter 22 to the DC bus 25 stabilizes near the voltage value specified by the DC bus voltage command value.

As described with reference to FIG. 2 , when the power generated by the photovoltaic power generation module 21 or the like exceeds the load power during stand-alone operation, the surplus power exceeding the load power is charged to the storage battery unit 23 via the bidirectional DC/DC converter 24. The storage battery unit 23 detects that its state of charge is fully charged (SOC (State of Charge) is 100%) and notifies the control unit 11. The control unit 11 receives the notification indicating the fully charged state from the storage battery unit 23 and performs DC bus voltage control on the bidirectional DC/DC converter 24 to suppress charging to the storage battery unit 23. Specifically, the control unit 11 outputs a current command value (BATI limit command value) as a DC bus voltage control command to the bidirectional DC/DC converter 24 so that the current value in the charging direction becomes "0 A." Based on the control command from the control unit 11, the bidirectional DC/DC converter 24 reduces the current value in the charging direction to the storage battery unit 23 to "0 A."

FIG. 4 is an explanatory diagram illustrating overcharging of the storage battery unit 23 due to a constant power flowing in the charging direction. FIG. 4 illustrates the relative magnitude relationship between the current command value (BATI limit command value) to the bidirectional DC/DC converter 24, represented by a solid line, and the actual current value (BATI), represented by a dashed line. As shown in FIG. 4 , if a constant power (also referred to as micropower) flowing in the charging direction of the storage battery unit 23 occurs between the current command value (BATI limit command value) to the bidirectional DC/DC converter 24 and the actual current value (BATI), the micropower current will flow into the storage battery unit 23 (several amperes in the example of FIG. 4 ). Examples of factors that can cause this constant power include measurement errors in the various sensors and measuring instruments included in the distributed power system 20. That is, in the bidirectional DC/DC converter 24, even if the current value (BATI) in the charging direction is controlled to "0 A" based on the current command value (BATI limit command value) from the control unit 11, the storage battery unit 23 continues to be charged by the minute current flowing in the charging direction even after the storage battery unit 23 has reached a fully charged state, which may cause an overvoltage state of the storage battery.

Figure 5 is an explanatory diagram illustrating the control operation of the distributed power system 20 according to this embodiment. When the charge rate of the storage battery unit 23 satisfies a predetermined condition during independent operation, the distributed power system 20 according to this embodiment controls the bidirectional DC/DC converter 24 and the DC/DC converter 22 so that power generated by the photovoltaic power generation module 21 or the like is given priority and output to the DC bus 25. Here, the predetermined condition refers to the charge rate for determining the state of charge of the storage battery unit 23 exceeding a predetermined threshold, which is set in advance based on the size and configuration of the distributed power system 20, the storage capacity of the storage battery unit 23, the load power supplied to the load 70 during independent operation, and the like. An example of the predetermined condition is the storage battery unit 23 being fully charged (in this case, the threshold is preferably about 95 percent, taking into account a margin). Below, the fully charged state of the storage battery unit 23 is described as the predetermined condition.

As shown in solid-line speech bubble A4 in Figure 5, the control unit 11 outputs a gate block command as a control command to the bidirectional DC/DC converter 24 in response to a notification from the storage battery unit 23 indicating a fully charged state. The bidirectional DC/DC converter 24 connected to the storage battery unit 23 stops BATI control based on the control command (gate block command) from the control unit 11, and cuts off the DC power in the charging direction supplied to the DC bus 25. Note that the DC/DC converter 22 connected to a power generation mechanism such as the solar power generation module 21 continues MPPT control, and DC power based on the power generated by the power generation mechanism is supplied to the DC bus 25.

As indicated by the diagonally hatched arrow A3 in Figure 5, the power conversion unit 12 of the PCS 10 converts the DC power supplied to the DC bus 25 into AC power synchronized with the power grid 80 and supplies it to the load 70 based on control commands from the control unit 11 (output voltage control (OUTV control), output current control (OUTI control)). In the distributed power system 20 of this embodiment, DC power supplied in the charging direction from the DC bus 25 to the power storage mechanism (storage battery unit 23) is cut off, and DC power supplied from the power generation mechanism (photovoltaic power generation module 21) to the DC bus 25 is given priority and supplied to the load 70. Therefore, in the distributed power system 20 of this embodiment, overcharging of the storage battery due to weak power flowing in the charging direction through the DC bus 25 can be prevented.

Furthermore, in the distributed power system 20 according to this embodiment, a control command to the bidirectional DC/DC converter 24 may be issued along with a gate block command to decrease the DC bus voltage command value in the discharge direction. In the distributed power system 20 according to this embodiment, the gate block for the bidirectional DC/DC converter 24 can be released in response to fluctuations in the power generated by the photovoltaic power generation module 21, etc., and the load power supplied to the load 70, and the power stored in the storage battery unit 23 can be supplied to the DC bus 20.

FIG. 6 is an explanatory diagram illustrating the voltage value of DC power supplied to the DC bus 25 in this embodiment. FIG. 6 illustrates the transition of control commands (DC bus voltage command values) for the DC/DC converter 22 and the bidirectional DC/DC converter 24 before and after full charge. In FIG. 6 , the control command represented by the dashed dotted line represents the DC bus voltage command value for the bidirectional DC/DC converter 24 (also referred to as a bidirectional DD), and the control command represented by the solid line represents the DC bus voltage command value for the DC/DC converter 22 (also referred to as a unidirectional DD). Hereinafter, to distinguish between the DC bus voltage command value for the bidirectional DC/DC converter 24 and the DC bus voltage command value for the DC/DC converter 22, the former will also be referred to as a "bidirectional command value" and the latter will also be referred to as a "unidirectional command value."

As shown in FIG. 6, until the storage battery unit 23 is fully charged (under normal circumstances), the DC/DC converter 22 performs MPPT control based on a control command (unidirectional command value) from the control unit 11, and the power generated by the solar power generation module 21, etc. is boosted to a predetermined voltage value and output to the DC bus 25. When the generated power exceeds the load power, the bidirectional DC/DC converter 24 performs BATI control in the charging direction based on the bidirectional command value, and the surplus power exceeding the load power is charged to the storage battery unit 23. Under normal circumstances, the same voltage value is specified for the bidirectional command value for the charging direction for the bidirectional DD 24 and the unidirectional command value for the unidirectional DD 22.

When the storage battery unit 23 reaches a fully charged state, the control unit 11 issues a gate block command to the bidirectional DC/DC converter 24 as a control command to double the voltage, and outputs a unidirectional command value in the discharge direction to the bidirectional DC/DC converter 24, which is a voltage value relatively lower than the bidirectional command value before full charge. As indicated by dashed-dotted bubbles A6 and A7, a bidirectional command value after full charge, which is lower by several volts from the bidirectional command value before full charge, is output to the bidirectional DC/DC converter 24. The amount of reduction in the bidirectional command value for the bidirectional DC/DC converter 24 is appropriately set depending on the configuration and scale of the distributed power system 20, the power consumption of the load 70 to which power is supplied during autonomous operation, and other factors. Then, as indicated by solid-line bubble A5, the control unit 11 outputs a control command (unidirectional command value) to the DC/DC converter 22 to continue MPPT control based on the DC bus voltage command value specified before full charge. DC power based on power generated by the photovoltaic power generation module 21 and other devices continues to be supplied to the DC bus 25.

Figure 7 is a time chart showing the progression of control operations of the distributed power supply system 20 of this embodiment. Figure 7 illustrates the progression of control operations of the DC/DC converter 22 (unidirectional DD) and the bidirectional DC/DC converter 24 (bidirectional DD) in response to load fluctuations and the like after full charge. The upper part of Figure 7 illustrates an SOC curve B1 that indicates the state of charge of the storage battery unit 23 during independent operation. During independent operation, the storage battery unit 23 reaches a fully charged state at timing t1.

As shown in FIG. 7, in the distributed operation system 20 of this embodiment, when the storage battery unit 23 is fully charged, the control unit 11 issues a gate block command as a control command to the bidirectional DD, cutting off power on the DC bus 25 in the charging direction. Then, the control unit 11 issues a DC bus voltage command value (bidirectional command value) that reduces the voltage value of the DC power in the discharging direction supplied from the bidirectional DD to the DC bus 25, as shown in DC bus voltage command value (bidirectional command value) B4.

Furthermore, the control unit 11 outputs a control command to the unidirectional DD to continue MPPT control based on the DC bus voltage command value specified before full charge, as indicated by the DC bus voltage command value (unidirectional command value) B2. In the distributed operation system 20 of this embodiment, the DC/DC converter 22 continues MPPT control based on the DC bus voltage command value specified before full charge, and DC power based on power generated by the photovoltaic power generation module 21 and the like is supplied to the DC bus 25. The power conversion unit 12 in the distributed power system 20 performs power conversion to supply power to the load 70 based on the DC power supplied from the unidirectional DD to the DC bus 25, thereby continuing independent operation. In the distributed operation system 20 after full charge, even if the power generated by the photovoltaic power generation module 21 and the like exceeds the load power, the gate block processing of the bidirectional DC/DC converter 24 blocks power flowing in the charging direction through the DC bus 25, preventing the storage battery unit 23 from being overcharged.

In the time chart of Figure 7, as shown by load power B7, it is assumed that the power to be supplied to load 70 increases at timing t2. As shown by DC bus voltage command value (unidirectional DD) B2, the control command (unidirectional command value) issued before full charge is maintained in the unidirectional DD. Similarly, as shown by DC bus voltage command value (bidirectional DD) B4, the control command issued at full charge (DC bus voltage command value that reduces the voltage value of the DC power in the discharge direction supplied from the bidirectional DD to the DC bus 25) is also maintained in the bidirectional DD.

In this state, if the power consumed by the load 70 increases, the voltage value of the DC power supplied to the DC bus 25 will decrease, as shown in the actual DC bus voltage B3. If the power consumed by the load 70 continues to increase, as shown in the load power B7, the voltage value of the DC power supplied to the DC bus 25 will further decrease and fall below the DC bus voltage command value for the discharge direction instructed to the bidirectional DD at full charge. In the bidirectional DD, as shown in the bidirectional DD power B6, at timing t3 when the voltage value of the DC bus 25 falls below the DC bus voltage command value for the discharge direction, the gate block instructed at full charge is released and BATI control for discharging the power stored in the storage battery unit 23 is initiated. In the bidirectional DD, BATI control for the discharge direction is performed using the control command (bidirectional command value) instructed at full charge as the target value, and DC power based on the power stored in the storage battery unit 23 is supplied to the DC bus 25.

As such, in the distributed power system 20 of this embodiment, even if the load power cannot be supplied solely by the power generated by the photovoltaic power generation modules 21, etc., resulting in a voltage drop on the DC bus 25, BATI control in the discharge direction can be initiated at timing t3 when the voltage value of the DC bus 25 falls below the bidirectional command value for the bidirectional DD. In this embodiment, by issuing a bidirectional command value ("A" in Figure 7) as a control command for the bidirectional DD, it is possible to supplement the power supplied from the unidirectional DD to the DC bus 25 in accordance with the amount of fluctuation in the power consumed by the load 70. Note that the command to release the gate block for the bidirectional DD may be, for example, a discharge current command value in the discharge direction for the bidirectional DD ("B" in Figure 7).

As shown in Figure 7, assume that the amount of power consumed by the load 70 decreases at time t4, as indicated by the load power B7. As indicated by the actual DC bus voltage B3, the voltage value of the DC bus 25 recovers in response to the decrease in the amount of power consumed by the load 70, and again exceeds the voltage value specified by the control command (bidirectional command value) issued to the bidirectional DD at full charge. Then, at time t5, when the voltage value of the DC bus 25 recovers to the target value (unidirectional command value) of the MPPT control for the unidirectional DD, as indicated by the actual DC bus voltage B3, the control unit 11 issues a control command to the bidirectional DD. As indicated by the DC bus voltage command value (bidirectional DD) B4, the voltage target value for the discharge direction of the BATI control, which was reduced at full charge, is reset to the voltage target value (bidirectional command value) for the charge direction before full charge. As shown at timing t6 for bidirectional power B6, the bidirectional DD starts BATI control in the charging direction based on the bidirectional command value from the control unit 11, and resumes charging of the energy storage unit 23 using surplus power. In the distributed operation system 20 according to this embodiment, the above-described control operation is repeated at timing t7, which indicates that the energy storage unit 23 is fully charged.

<Controller configuration>
8 is a diagram illustrating an example of the hardware configuration of the control unit 11 of the PCS 10 according to this embodiment. As shown in FIG. 8, the control unit 11 is a computer including, as components, a processor 101, a main memory device 102, an auxiliary memory device 103, a communication IF 104, and an input/output IF 105, all of which are interconnected by a connection bus 106. The main memory device 102 and the auxiliary memory device 103 are recording media readable by the control unit 11. Each of the above components may be provided in multiple units, or some of the components may not be provided. Note that the microcomputers provided in the storage battery unit 23, the bidirectional DC/DC converter 24, and the DC/DC converter 22 are realized by hardware configurations substantially equivalent to that of the control unit 11.

The processor 101 is a central processing unit that controls the entire control unit 11. The processor 101 is, for example, a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), or a DSP (Digital Signal Processor). The processor 101, for example, deploys a program stored in the auxiliary storage device 103 in an executable manner in a working area of the main storage device 102, and controls peripheral devices through the execution of the program, thereby providing functions that meet a predetermined purpose. However, it should be noted that some or all of the functions provided by the processor 101 may be implemented by an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), or the like.
) etc. Similarly, some or all of the functions may be realized by a dedicated LSI (large scale integration) such as an FPGA (Field-Programmable Gate Array) or a numerical calculation processor, or other hardware circuit.

The main memory device 102 and the auxiliary memory device 103 constitute the memory of the control unit 11. The main memory device 102 stores programs executed by the processor 101, data processed by the processor, etc. The main memory device 102 includes a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary memory device 103 is a storage medium that stores programs executed by the processor 101, etc., operation setting information, etc. The auxiliary memory device 103 is, for example, a hard-disk drive (HDD), a solid-state drive (SSD), an erasable programmable ROM (EPROM), a flash memory, a USB memory, an SD card, etc.
(Secure Digital) memory cards and the like. The communication IF 104 is a communication interface with the communication network. The communication IF 104 can have an appropriate configuration depending on the connection method with the communication network. In this embodiment, various control commands are communicated between the DC/DC converter 22, the storage battery unit 23, and the bidirectional DC/DC converter 24, which are connected via the communication IF 104. The input/output IF 15 is an interface for inputting and outputting data between the input and output devices of the PCS 10. Data is output via the input/output IF 15 to a display device such as an LCD or an output device such as a printer connected to the PCS 10. Operation instructions are also accepted via the input/output IF 15, and processing intended by the operator is performed based on the operation instructions. Furthermore, in this embodiment, output signals from various sensors, including a power sensor 26 (current sensor, voltage sensor), a power sensor 27, and a power meter 81, which are connected to the DC bus 25, are input to the control unit 11 via the input/output IF 15.

<Processing flow>
Fig. 9 is a flowchart showing an example of an overcharge prevention process provided by the control unit 11 according to this embodiment. In the flow of Fig. 9, a process is performed in which the DC power supplied from the DC bus 25 to the power storage mechanism side in the charging direction is cut off, and the DC power supplied from the power generation mechanism side to the DC bus 25 is given priority and supplied to the load 70. In the control unit 11 of the PCS 10 according to this embodiment, the overcharge prevention process is executed during independent operation.

After the process starts, the distributed power system 20 performs independent operation based on the power generated by the photovoltaic power generation modules 21 and the like (step S101). That is, the DC/DC converter 22 performs MPPT control based on a control command (DC bus voltage command value) from the control unit 11, boosts the power generated by the photovoltaic power generation modules 21 and the like to a predetermined voltage value, and outputs the boosted power to the DC bus 25. Furthermore, when the power generated by the photovoltaic power generation modules 21 and the like exceeds the load power, the bidirectional DC/DC converter 24 performs DC bus voltage control (BATI control) based on a control command from the control unit 11, converts the voltage of the DC power supplied to the DC bus 25, and charges the storage battery unit 23. After the process of step S101, the process proceeds to step S102.

In step S102, it is determined whether the charge rate of the storage battery unit 23 satisfies a predetermined condition. Such a determination condition is set in advance based on the scale and configuration of the distributed power supply system 20, the storage capacity of the storage battery unit 23, the load power supplied to the load 70 during independent operation, etc. A typical example of the determination condition is whether the state of charge of the storage battery unit 23 is fully charged (SOC (State of Charge)
In step S103, the control unit 11 determines whether the charge rate of the storage battery unit 23 is in a fully charged state (95 to 100 percent). The control unit 11 determines the charge state of the storage battery unit 23 based on the notification indicating the fully charged state of the storage battery unit 23 obtained through the communication IF 104. In step S102, if the charge rate of the storage battery unit 23 satisfies a predetermined condition (if the charge state is fully charged) (step S102, "Yes"), the process proceeds to step S103. If not (step S102, "No"), the process returns to step S101. In step S103, if a gate block command is output as a control command to the bidirectional DC/DC converter 24 connected to the storage battery unit 23, the process proceeds to step S104. The bidirectional DC/DC converter 24 stops the BATI control based on the control command (gate block command) from the control unit 11, and the DC power supplied to the storage battery unit 23 from the DC bus 25 in the charge direction is cut off.

In step S104, the conditions for releasing the gate block after full charge are output as a control command to the bidirectional DC/DC converter 24. That is, a DC bus voltage command value in the discharge direction, which is a voltage value several volts lower than the DC bus voltage command value before full charge, is specified as a control command. As explained using Figures 6 and 7, even if the load power cannot be supplied solely with the power generated by the photovoltaic power generation module 21, etc., causing a voltage drop on the DC bus 25, BATI control in the discharge direction can be started when the voltage value on the DC bus 25 falls below the DC bus voltage command value in the discharge direction for the bidirectional DC/DC converter 24.

The condition for releasing the gate block after full charge may be a discharge current command value in the discharge direction. The control unit 11 of the PCS 10 acquires the sensor output value of the power sensor 26 (current sensor, voltage sensor) provided on the DC bus 25 via the input/output IF 15. Then, based on the acquired output value of the power sensor 26, if the voltage value of the DC bus 25 is lower than the DC bus voltage command value for the DC/DC converter 22, the discharge current command value in the discharge direction can be output as a control command for the bidirectional DC/DC converter 24 after full charge. The bidirectional DC/DC converter 24 releases the gate block based on the control command from the control unit 11 and starts BATI control in the discharge direction. After processing step S104, processing proceeds to step S105.

In step S105, MPPT control based on the DC bus voltage command value for the DC/DC converter 22 before full charge is continued. That is, the control unit 11 outputs a control command to the DC/DC converter 22 to maintain the DC bus voltage command value for the DC/DC converter 22 before full charge. The DC/DC converter 22 maintains MPPT control with the DC bus voltage command value before full charge as a target value based on the control command from the control unit 11, and DC power obtained by converting the voltage value of power generated by the photovoltaic power generation module 21, etc. is supplied to the DC bus 25. The power conversion unit 12 of the distributed power system 20 controls the DC bus 25
The DC power supplied to the load 70 is converted into AC power synchronized with the power grid 80 and supplied to the load 70. After the process of step S105, this routine is temporarily ended.

As described above, in the distributed power system 20 according to this embodiment, when the charge rate of the storage battery unit 23 satisfies a predetermined condition (i.e., the storage battery unit 23 is fully charged), the bidirectional DC/DC converter 24 and the DC/DC converter 22 can be controlled to prioritize the output of power generated by the photovoltaic power generation module 21, etc., with respect to the DC power supplied to the DC bus 25. The control unit 11 of the PCS 10 constituting the distributed power system 20 can, for example, output a gate block command for the charge direction as a control command to the bidirectional DC/DC converter 24 in response to a notification from the storage battery unit 23 indicating a fully charged state. The bidirectional DC/DC converter 24 can stop BATI control based on the gate block command from the control unit 11, thereby cutting off the DC power supplied from the DC bus 25 to the storage battery unit 23. Furthermore, the control unit 11 can output a control command to the DC/DC converter 22 to maintain the DC bus voltage command value before full charge and continue MPPT control based on the power generated by the photovoltaic power generation module 21, etc. As a result, in the distributed power generation system 20 according to this embodiment, the DC power supplied from the DC bus 25 to the power storage mechanism side is cut off, and the DC power supplied from the power generation mechanism side to the DC bus 25 can be given priority and supplied to the load 70. The distributed power generation system 20 according to this embodiment can prevent overcharging of the storage battery due to minute power flowing in the charging direction through the DC bus 25 during independent operation.

In addition, in this embodiment, the control unit 11 of the PCS 10 constituting the distributed power system 20 can output a DC bus voltage command value (bidirectional command value), which is the target value for BATI control in the discharge direction, as a control command to the bidirectional DC/DC converter 24 when the charge rate from the storage battery unit 23 satisfies a predetermined condition. Here, the voltage value of the DC bus voltage command value in the discharge direction output after full charge is lowered by several volts than the voltage value of the DC bus voltage command value in the charge direction before full charge. Therefore, even if the load power cannot be supplied solely by the power generated by the photovoltaic power generation module 21, etc., resulting in a voltage drop on the DC bus 25, BATI control in the discharge direction can be initiated when the voltage value of the DC bus 25 falls below the DC bus voltage command value in the discharge direction for the bidirectional DC/DC converter 24. In this embodiment, by specifying a DC bus voltage command value in the discharge direction as a control command to the bidirectional DC/DC converter 24, it is possible to supplement the amount of power supplied to the DC bus 25 via the bidirectional DC/DC converter 24 in accordance with the amount of fluctuation in power consumed by the load 70 and the power generated by the solar power generation module 21, etc.

(others)
The above-described embodiment is merely an example, and the disclosure of the present embodiment may be modified as appropriate within the scope of the gist thereof. The processes and means described in this disclosure may be freely combined and implemented as long as no technical contradictions arise. For example, the embodiment disclosed in this embodiment may be applied to an electric vehicle (EV) equipped with a storage battery such as a battery and a power generation mechanism using regenerative energy. Furthermore, the embodiment may be applied to a solar car equipped with a solar power generation module as a power generation mechanism, or a fuel cell car equipped with a fuel cell. Even in such an embodiment, overcharging of the storage battery can be prevented when the charging rate of the storage battery unit 23 satisfies a predetermined condition.

Furthermore, processing described as being performed by one device may be shared and executed by multiple devices. Alternatively, processing described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration used to realize each function can be flexibly changed.

<<Computer-readable recording medium>>
A program that causes an information processing device or other machine or device (hereinafter referred to as a computer, etc.) to realize any of the above functions can be recorded on a computer-readable recording medium. Then, the computer, etc. can provide the function by reading and executing the program from the recording medium.

Here, a computer-readable recording medium refers to a recording medium that stores information such as data and programs electrically, magnetically, optically, mechanically, or chemically, and that can be read by a computer. Examples of such recording media that can be removed from a computer include flexible disks, magneto-optical disks, CD-ROMs, CD-R/Ws, DVDs, Blu-ray discs, DAT, 8mm tape, and memory cards such as flash memory. Additionally, examples of recording media that are fixed to a computer include hard disks and ROMs.

In the following, the constituent elements of the present invention will be described with reference to the reference numerals in the drawings in order to make it possible to compare the constituent elements of the present invention with the configurations of the embodiments.
<Invention 1>
A power supply system (20) including a power generation device (21), a storage battery (23), and a power converter (10) capable of independent operation that supplies power to a consumer load (70) based on DC power supplied to a power bus (25) from at least one of the power generation device (21) and the storage battery (23), the power supply system (20) being operated in connection with a power grid (80) of the consumer,
The power converter (10) includes a control unit (11) that controls DC power supplied to the power bus (25);
a first power conversion unit (22) that converts the voltage of DC power generated by the power generation device (21) based on a control command related to maximum power point tracking control from the control unit (11) and supplies the converted voltage to the power bus (25);
a second power conversion unit (24) connected to the power bus (25) and converting the voltage of DC power supplied to the power bus (25) based on a charge/discharge control command from the control unit (11) regarding charge/discharge control to charge the storage battery (23), or converting the voltage of DC power discharged from the storage battery (23) to supply the power bus (25),
When the amount of power generated by the power generation device (21) exceeds the amount of load power consumed by the load (70) and the state of charge of the storage battery (23) satisfies a predetermined condition during the independent operation, the control unit (11) maintains a target value in the maximum power point tracking control before the state of charge of the storage battery (23) satisfies the predetermined condition as a control command to the first power conversion unit (22), and
a gate block instruction for stopping the charge/discharge control as a charge/discharge control command to the second power conversion unit (24), and cutting off the DC power supplied from the power bus (25);
A power supply system (20).

1 Power supply system 10 Power conditioner (PCS)
11 Control unit 12 Power conversion unit 20 Distributed power supply system (power supply system)
21. Solar power generation module (power generation device)
22 DC/DC converter (first power conversion unit)
23 Battery unit (battery)
24 Bidirectional DC/DC converter (second power conversion unit)
25 DC bus (power bus)
26 Power sensor 70 Load 80 Power system 81 Power meter 101 Processor 102 Main memory device 103 Auxiliary memory device 104 Communication IF
105 Input/Output IF
106 Connection bus

Claims (3)

A power supply system including a power generation device, a storage battery, and a power converter capable of independent operation that supplies power to a consumer load based on DC power supplied to a power bus from at least one of the power generation device and the storage battery,
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
the control unit issues a gate block instruction to the second power conversion unit when, during the independent operation, the amount of power generated by the power generation device exceeds the amount of load power consumed by the load, and the storage battery is in a fully charged state or when the charging rate of the storage battery exceeds 95 percent;
the second power conversion unit stops voltage control of the power bus based on the gate block instruction and cuts off DC power in a charging direction supplied from the power bus to the storage battery ;
when the control unit detects a voltage drop of the DC power supplied to the power bus after issuing the gate block instruction, the control unit issues an instruction to the second power conversion unit to cancel the gate block instruction;
the second power conversion unit starts voltage control of the power bus based on an instruction to release the gate block instruction, and supplies the stored power charged in the storage battery to the power bus.
A power supply system characterized by: A control method executed by a power converter of a power supply system including a power generation device, a storage battery, and a power converter capable of independent operation that supplies power to a load of a consumer based on DC power supplied to a power bus from at least one of the power generation device and the storage battery, the method comprising:
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
the control unit issues a gate block instruction to the second power conversion unit when, during the independent operation, the amount of power generated by the power generation device exceeds the amount of load power consumed by the load, and the storage battery is in a fully charged state or when the charging rate of the storage battery exceeds 95 percent;
the second power conversion unit stops voltage control of the power bus based on the gate block instruction and cuts off DC power in a charging direction supplied from the power bus to the storage battery ;
when the control unit detects a voltage drop of the DC power supplied to the power bus after issuing the gate block instruction, the control unit issues an instruction to the second power conversion unit to cancel the gate block instruction;
the second power conversion unit starts voltage control of the power bus based on an instruction to release the gate block instruction, and supplies the stored power charged in the storage battery to the power bus.
A control method for performing this. A program to be executed by a power converter of a power supply system including a power generation device, a storage battery, and a power converter capable of independent operation that supplies power to a load of a consumer based on DC power supplied to a power bus from at least one of the power generation device and the storage battery,
The power converter includes a control unit that controls DC power supplied to the power bus;
a first power conversion unit that converts the voltage of DC power generated by the power generation device based on a control command from the control unit and supplies the converted voltage to the power bus;
a second power conversion unit connected to the power bus, which converts the voltage of DC power supplied to the power bus based on a charge/discharge control command from the control unit regarding charge/discharge control, and charges the storage battery, or converts the voltage of DC power discharged from the storage battery and supplies the power bus,
the control unit issues a gate block instruction to the second power conversion unit when, during the independent operation, the amount of power generated by the power generation device exceeds the amount of load power consumed by the load, and the storage battery is in a fully charged state or the charging rate of the storage battery exceeds 95 percent;
causing the second power conversion unit to stop voltage control of the power bus based on the gate block instruction and cut off DC power in a charging direction supplied from the power bus to the storage battery ;
the control unit instructs the second power conversion unit to cancel the gate block instruction when a voltage drop of the DC power supplied to the power bus is detected after the gate block instruction is issued;
starting voltage control of the power bus based on an instruction to the second power conversion unit to cancel the gate block instruction, and supplying the stored power charged in the storage battery to the power bus;
A program that executes the following.