Power generation system, control method and program

Abstract

To prevent overcharge of a storage battery during an autonomous operation of a distributed power system comprising a power generation mechanism and a power storage mechanism.SOLUTION: A power converter comprises: a control unit; a first power conversion unit that converts a voltage of DC power generated by a power generation device on the basis of a control command related to maximum power point follow-up control from the control unit and supplies the voltage to a power bus; and a second power conversion unit that is connected with the power bus, converts the voltage of the DC power supplied to the power bus on the basis of a charge-discharge control command related to charge-discharge control from the control unit and charges a storage battery, or converts the voltage of the DC power discharged from the storage battery and supplies the voltage to the power bus. When a state of charge of the storage battery satisfies a predetermined condition during an autonomous operation, the control unit maintains a target value in the maximum power point follow-up control before the state of charge of the storage battery satisfies the predetermined condition, and performs a gate block instruction to stop the charge-discharge control as a charge-discharge control command to the second power conversion unit to block the DC power supplied from the power bus.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a distributed power supply system including a power generation mechanism such as a solar power generation system and a power storage mechanism such as a battery system, a control method, and a program. [Background technology]

[0002] In recent years, distributed power generation systems that include a power generation mechanism such as a solar power generation system and a power storage mechanism such as a battery system and that are operated in connection with a commercial power grid have become widespread (for example, Patent Document 1). Consumers can, for example, convert the power generated by solar power generation into alternating current and supply it to a load or the connected power grid, and store surplus power to use it during the daytime when power demand is tight, thereby enabling peak shifting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-125974 Summary of the Invention [Problem to be solved by the invention]

[0004] In a distributed power system, when a load is operated autonomously without using power supplied from a commercial power grid, if the power generated by a photovoltaic power generation system or the like exceeds the load power, the surplus power is charged into a storage battery provided in a storage battery system or the like. In a distributed power system, a power converter connected to a power generation mechanism and a power converter connected to a power storage mechanism are connected by a DC bus. When the storage battery is fully charged, the power converter on the storage battery side prevents the storage battery from being overcharged by suppressing 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 with a constant power (low power) continues, which could cause an overvoltage state of the storage battery.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a technology for preventing overcharging of a storage battery during independent operation of a distributed power generation system equipped with a power generation mechanism and a storage mechanism. [Means for solving the problem]

[0006] 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:

[0007] As a result, in the power supply system, when the state of charge of storage battery unit 23, which is a storage battery, satisfies a predetermined condition, with regard to the DC power supplied to DC bus 25, which is a power bus, bidirectional DC / DC converter 24, which is a second power conversion unit, can be controlled to cut off DC power supplied in the charging direction from DC bus 25. Then, DC / DC converter 22, which is a first power conversion unit, can be controlled so that DC power generated by photovoltaic power generation module 21, which is a power generation device, is supplied to DC bus 25, just as before the full charge state. Because the power supply system can cut off DC power supplied in the charging direction from DC bus 25, it is possible to reliably prevent overcharging of the storage battery due to minute power flowing in the charging direction through DC bus 25 during standalone operation. Then, because DC power generated by photovoltaic power generation module 21 can be supplied to DC bus 25, just as before the full charge state, standalone operation can be continued in which power is supplied to load 70, which is a load, based on the generated power.

[0008] In one embodiment of the disclosed technology, the control unit may detect a voltage drop of the DC power supplied to the power bus, and issue a charge / discharge control command to the second power conversion unit to cancel 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 cancel the gate block in response to a voltage drop of 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.

[0009] In addition, 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 lower than a first voltage value that is a target value of 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 supply of DC power based on the storage power charged in the storage battery to the power bus.

[0010] 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, on the condition 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 in a case where the load power cannot be supplied solely with the DC power generated by the photovoltaic power generation module 21 and a voltage drop occurs 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 accordance with fluctuations in the power consumed by the load 70 and fluctuations in the power generated by the photovoltaic power generation module 21, etc., and the amount of power can be supplemented based on the stored power.

[0011] 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.

[0012] Even in this configuration, when a predetermined condition of the storage battery unit 23, which is a storage battery, is satisfied, 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 fully charged 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 fully charged 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.

[0013] 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 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.

[0014] Even in this configuration, 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 a second power conversion unit, can be controlled 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. Then, the DC / DC converter 22, which is a first power conversion unit, can be controlled so that the DC power generated by the photovoltaic power generation module 21, which is a power generation device, is supplied to the DC bus 25 in the same way as before the full charge state. In the power supply system, the DC power supplied in the charging direction from the DC bus 25 can be cut off, which reliably prevents overcharging of the storage battery due to minute power flowing in the charging direction through the DC bus 25 during stand-alone operation. Furthermore, the DC power generated by the photovoltaic power generation module 21 can be supplied to the DC bus 25 in the same way as before the fully charged state, so stand-alone operation can be continued in which power is supplied to the load 70 based on the generated power. [Effects of the Invention]

[0015] According to the present invention, it is possible to prevent overcharging of a storage battery during stand-alone operation of a distributed power supply system including a power generation mechanism and a power storage mechanism. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a schematic configuration of a distributed power supply system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram illustrating the flow of power during independent operation in the first embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory diagram illustrating a control operation during independent operation in the first embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram illustrating overcharging of a storage battery unit due to minute power in the first embodiment of the present invention. [Figure 5] 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. [Figure 6] 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. [Figure 7] 4 is a time chart showing the progress of the control operation of the distributed power generation system in the first embodiment of the present invention. [Figure 8] 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. [Figure 9] 4 is a flowchart showing an example of an overcharge prevention process in the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] [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 shows an example of 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.

[0018] As shown in Fig. 1, a distributed power system 20 includes a photovoltaic 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 photovoltaic 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.

[0019] The control unit 11 of the PCS 10 includes 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 power sensor 28 (current sensor, voltage sensor) provided on the DC bus 25. The outputs of various sensors are input, including a power sensor 27 (current sensor, voltage sensor) installed in the power distribution board 82 and a power meter 81 installed on a power line 83 connecting the power distribution board 82 and the power grid 80. Based on the information detected through 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 photovoltaic power generation module 21 is maximized or at the optimum operating point. The control unit 11 performs control processing related to charging and discharging based on the load conditions detected through the various sensors and preset modes related to charging and discharging.

[0020] 2 and 3, in a distributed power system 20 according to an example application, when independent operation is performed, power generated by a photovoltaic power generation module 21 and the like is supplied to a DC bus 25 via a DC / DC converter 22. When the power generated by the photovoltaic power generation module 21 and the like exceeds load power, the surplus power exceeding the load power is charged to a storage battery unit 23 via a bidirectional DC / DC converter 24. Here, as shown in FIG. 4, when a certain amount of power (micro power) in the charging direction to the storage battery unit 23 occurs between a current command value (BATI limit command value) to the bidirectional DC / DC converter 24 and the actual current value (BATI), the micro power current flows into the storage battery unit 23, which may cause an overvoltage state of the storage battery.

[0021] 5 to 9 , in a distributed power system 20 according to an example application, when the state of charge of the storage battery unit 23 satisfies a predetermined condition, the bidirectional DC / DC converter 24 and the DC / DC converter 22 are controlled so that power generated by the photovoltaic power generation module 21 and the like is given priority and output 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 given priority and supplied to the load 70. In addition, a DC bus voltage command value in the discharging direction for the bidirectional DC / DC converter 24 is set lower than a DC bus voltage command value for the DC / DC converter 22. Here, the predetermined condition is a threshold value for the state of charge for determining the state of charge 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 the predetermined condition is a fully charged state of the storage battery unit 23. 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 power flowing in the charging direction through the DC bus 25 during stand-alone operation.

[0022] Example 1 Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0023] <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 board 82. Note that this embodiment will be described using a solar power generation system as a power generation mechanism, but 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.

[0024] The distributed power supply system 20 of this embodiment includes a photovoltaic 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 photovoltaic 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 supply system 20 of this embodiment, the PCS 10 and the photovoltaic power generation module 21 constitute a photovoltaic power generation system, and the PCS 10 and the storage battery unit 23 constitute a storage battery system. The distributed power supply system 20 of this embodiment corresponds to a "power supply system."

[0025] The DC / DC converter 22 and the bidirectional DC / DC converter 24 of the PCS 10 according to 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 the 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 photovoltaic 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 included in the power conditioner (PCS) 10 according to this embodiment corresponds to a "first power conversion unit," and the bidirectional DC / DC converter 24 corresponds to a "second power conversion unit." Moreover, the DC bus 25 to which the DC / DC converter 22 and the bidirectional DC / DC converter 24 according to this embodiment are connected corresponds to the "power bus."

[0026] The DC / DC converter 22 is a unit for boosting the DC power generated by the photovoltaic power generation module 21 and supplying it to the DC bus 25. The storage battery unit 23 is a storage battery that stores a predetermined capacity of power determined by its rating or the like, and the number of times it can be charged and discharged is limited by the rating or the like. 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, the storage battery unit 23, and the bidirectional DC / DC converter 24 each incorporate a microcomputer or the like that operates in response to a control command from the control unit 11.

[0027] The control unit 11 of the PCS 10 is a unit including a processor (such as a CPU), a memory, a gate driver, a communication interface circuit, etc. The outputs of various sensors are input to the control unit 11, 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 power meter 81 provided on a power line 83 connecting a distribution board 82 and a power grid 80. Based on 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 point (value of current x voltage) where the power output of the photovoltaic power generation module 21 is maximized or at the optimal operating point.

[0028] Furthermore, the control unit 11 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, a preset charging and discharging mode, etc. 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.

[0029] Furthermore, when the control unit 11 determines to perform charging based on the above mode, load conditions, the charging state of the storage battery unit 23, and the like, it controls the conversion of 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 charges the storage battery unit 23. Upon receiving a control command from the control unit 11 regarding the above power storage control process, the operations of the storage battery unit 23 and the bidirectional DC / DC converter 24 are controlled.

[0030] FIG. 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 photovoltaic 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 a control command from the control unit 11, converts the power generated by the photovoltaic power generation modules 21 and the like to a predetermined voltage value, and outputs the converted voltage 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 a control command from the control unit 11, and supplies the AC power to the load 70 (output voltage control (OUTV control) and output current control (OUTI control)). 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. 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.

[0031] FIG. 3 is an explanatory diagram illustrating control operations during isolated operation. FIG. 3 illustrates an example of control of the DC / DC converter 22 (also referred to as a unidirectional DD) with respect to the DC bus voltage detected via the power sensor 26 (current sensor, voltage sensor). As shown in FIG. 3, during isolated operation, 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 module 21, etc., to a predetermined voltage value, and outputs the boosted power to the DC bus 25. When the DC bus voltage detected via the power sensor 26 (current sensor, voltage sensor) exceeds a 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 is stabilized near the voltage value specified by the DC bus voltage command value.

[0032] As explained in 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 is charged when its own state of charge is fully charged (SOC (State of Charge) is 100%). The control unit 11 detects that the storage battery unit 23 is in a fully charged state 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". The bidirectional DC / DC converter 24 reduces the current value in the charging direction to the storage battery unit 23 to "0 A" based on the control command from the control unit 11.

[0033] 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 broken line. As shown in FIG. 4, there is a relationship between the current command value (BATI limit command value) to the bidirectional DC / DC converter 24 and the actual current value (BATI). When a certain amount of power (also referred to as micro-power) flows in the charging direction to the unit 23, the current of the micro-power flows into the storage battery unit 23 (several amperes in the example of FIG. 4). Examples of factors that cause such a certain amount of power include measurement errors of the various sensors and measuring instruments included in the distributed power system 20. That is, even if the bidirectional DC / DC converter 24 controls the current value (BATI) in the charging direction to "0 A" based on the current command value (BATI limit command value) from the control unit 11, the bidirectional DC / DC converter 24 continues to charge the storage battery unit 23 with micro-power. Even after the storage battery unit 23 is fully charged, it is gradually charged by the micro-power current flowing in the charging direction, which may cause an overvoltage state of the storage battery.

[0034] FIG. 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 and the like is given priority and output to the DC bus 25. Here, the predetermined condition refers to the charge rate for determining the charge state 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 fully charged state of the storage battery unit 23 (in this case, the threshold is preferably about 95% considering a margin). The following description will be given assuming the fully charged state of the storage battery unit 23 as the predetermined condition.

[0035] 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 full charge state. The bidirectional DC / DC converter 24 connected to the storage battery unit 23 stops the 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.

[0036] As indicated by an arrow A3 hatched with diagonal lines in Fig. 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 based on a control command from the control unit 11, and supplies the AC power to the load 70 (output voltage control (OUTV control) and output current control (OUTI control)). In the distributed power system 20 according to 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 can be given priority and supplied to the load 70. Therefore, in the distributed power system 20 according to this embodiment, it is possible to prevent overcharging of the storage battery due to weak power flowing in the charging direction through the DC bus 25.

[0037] Furthermore, in the distributed power supply system 20 according to this embodiment, an instruction to decrease the DC bus voltage command value in the discharge direction may be issued together with a gate block command as a control command to the bidirectional DC / DC converter 24. In the distributed power supply system 20 according to this embodiment, it becomes possible to release the gate block for the bidirectional DC / DC converter 24 and supply the power stored in the storage battery unit 23 to the DC bus 20 in accordance with fluctuations in the power generated by the photovoltaic power generation module 21 or the like and the load power supplied to the load 70.

[0038] 6 is an explanatory diagram illustrating the voltage value of the DC power supplied to the DC bus 25 in this embodiment. In FIG. 6, the DC / DC converter 22 and the dual-phase converter 23 are connected to each other before and after full charge. 6 illustrates the transition of the control commands (DC bus voltage command values) for the bidirectional DC / DC converters 24. In Fig. 6, the control commands represented by the dashed dotted line represent the DC bus voltage command values ​​for the bidirectional DC / DC converter 24 (also referred to as bidirectional DD), and the control commands represented by the solid line represent the DC bus voltage command values ​​for the DC / DC converter 22 (also referred to as unidirectional DD). Hereinafter, in order 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 the "bidirectional command value" and the latter will also be referred to as the "unidirectional command value."

[0039] 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 photovoltaic power generation module 21 and the like 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 to the bidirectional DD 24 and the unidirectional command value to the unidirectional DD 22.

[0040] When the storage battery unit 23 reaches a full charge state, the control unit 11 issues a gate block command to the bidirectional DC / DC converter 24 as a control command to multiply the voltage, and outputs a unidirectional command value in the discharge direction to the bidirectional DC / DC converter 24, the unidirectional command value being a voltage value relatively lower than the bidirectional command value before full charge. As indicated by dashed-dotted arrows A6 and A7, a bidirectional command value after full charge, lowered 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 arrow 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 the like is continuously supplied to the DC bus 25.

[0041] Fig. 7 is a time chart showing the transition of the control operation of the distributed power supply system 20 of this embodiment. Fig. 7 illustrates the transition of the control operation 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 Fig. 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.

[0042] 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 to cut off the power of the DC bus 25 in the charging direction. Then, the control unit 11 issues a DC bus voltage command value (bidirectional command value) to reduce the voltage value of the DC power in the discharging direction supplied from the bidirectional DD to the DC bus 25, as indicated by a DC bus voltage command value (bidirectional command value) B4.

[0043] 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 the power generated by the photovoltaic power generation module 21 or the like is supplied to the DC bus 25. The power conversion unit 12 in the distributed power supply system 20 outputs a control command to the DC bus 25 from the unidirectional DD. Based on the DC power supplied to the storage battery unit 23, power conversion is performed to supply power to the load 70, and independent operation continues. In the distributed operation system 20, even if the power generated by the photovoltaic power generation module 21 or the like exceeds the load power after the storage battery unit 23 is fully charged, the gate blocking process of the bidirectional DC / DC converter 24 blocks the power flowing in the charging direction through the DC bus 25, so the storage battery unit 23 will not be overcharged.

[0044] 7, it is assumed that the power to be supplied to the load 70 increases at timing t2, as indicated by load power B7. As indicated 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 indicated by DC bus voltage command value (bidirectional DD) B4, the control command issued before full charge (the DC bus voltage 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) is also maintained in the bidirectional DD.

[0045] 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 decreases, as indicated by the actual DC bus voltage B3. If the power consumed by the load 70 continues to increase, as indicated by the load power B7, the voltage value of the DC power supplied to the DC bus 25 further decreases and falls below the DC bus voltage command value for the discharge direction instructed to the bidirectional DD at the time of full charge. In the bidirectional DD, as indicated by 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 the time of full charge is released, and BATI control for discharging the power stored in the storage battery unit 23 is started. In the bidirectional DD, BATI control for the discharge direction is performed using the control command (bidirectional command value) instructed at the time of full charge as a target value, and DC power based on the power stored in the storage battery unit 23 is supplied to the DC bus 25.

[0046] As described above, 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 module 21 or the like, resulting in a voltage drop on the DC bus 25, BATI control in the discharge direction can be started 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 FIG. 7) as a control command for the bidirectional DD, it becomes 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 FIG. 7).

[0047] As shown in the load power B7 in FIG. 7, it is assumed that the amount of power consumed by the load 70 decreases at time t4. As shown in 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) given 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 MPPT control for the unidirectional DD as shown in the actual DC bus voltage B3, the control unit 11 issues a control command to the bidirectional DD. As shown in the DC bus voltage command value (bidirectional DD) B4, the voltage target value in the discharge direction of the BATI control, which was reduced at full charge, is reset to the voltage target value in the charge direction (bidirectional command value) before full charge. As shown in the bidirectional power B6 at time t6, the bidirectional DD starts BATI control in the charge direction based on the bidirectional command value from the control unit 11, and resumes charging 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 power storage unit 23 is in a fully charged state.

[0048] <Controller configuration> Fig. 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, 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 a hardware configuration substantially equivalent to that of the control unit 11.

[0049] 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, 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), a numerical calculation processor, or other hardware circuit.

[0050] 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., and operation setting information, etc. The auxiliary memory device 103 may be, for example, a hard-disk drive (HDD), a solid-state drive (SSD), an erasable programmable ROM (EPROM), a flash memory, a USB memory, or an SD (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 to be connected. 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 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, connected to the DC bus 25, are input to the control unit 11 via the input / output IF 15.

[0051] <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 in the charging direction 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 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.

[0052] After the process starts, the distributed power supply system 20 performs independent operation based on the power generated by the photovoltaic power generation module 21 or the like (step S101). The inverter 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 module 21 etc. to a predetermined voltage value, and outputs it to the DC bus 25. Furthermore, when the power generated by the photovoltaic power generation module 21 etc. 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 processing of step S101, the processing proceeds to step S102.

[0053] In step S102, it is determined whether the state of charge 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 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) It is determined whether the charge is between 95 percent and 100 percent. The control unit 11 determines the state of charge of the storage battery unit 23 based on a notification indicating the full charge state of the storage battery unit 23 acquired through the communication IF 104. In step S102, if the charge rate of the storage battery unit 23 satisfies a predetermined condition (if the state of charge is full charge) (step S102, "Yes"), the process proceeds to step S103; if not (step S102, "No"), the process returns to step S101. In step S103, when 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.

[0054] In step S104, a condition for releasing the gate block after full charge is 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 that is several volts lower than the DC bus voltage command value before full charge, is instructed as a control command. As described with reference to Figs. 6 and 7, even if the load power cannot be supplied only with the power generated by the photovoltaic power generation module 21 or the like, causing a voltage drop on the DC bus 25, the BATI control in the discharge direction can be started at the timing 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.

[0055] 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 a 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, if the voltage value of the DC bus 25 is lower than the DC bus voltage command value for the DC / DC converter 22 based on the acquired output value of the power sensor 26, a discharge current command value in the discharge direction may 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 in step S104, the process proceeds to step S105.

[0056] 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.

[0057] 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 (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 output of power generated by the photovoltaic power generation module 21 and the like with respect to DC power supplied to the DC bus 25. The control unit 11 of the PCS 10 constituting the distributed power system 20 can output a gate block command for the charge direction as a control command to the bidirectional DC / DC converter 24, triggered, for example, by a notification indicating a fully charged state from the storage battery unit 23. The bidirectional DC / DC converter 24 can stop BATI control based on the gate block command from the control unit 11, thereby cutting off DC power supplied from the DC bus 25 to the storage battery unit 23. The control unit 11 can also output a control command to the DC / DC converter 22 to maintain the DC bus voltage command value before full charge and to continue MPPT control based on the power generated by the photovoltaic power generation module 21 and the like. As a result, in the distributed power supply 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 supply 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.

[0058] 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 a target value for BATI control in the discharging 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 discharging direction output after full charge is lowered by several volts than the voltage value of the DC bus voltage command value in the charging 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 or the like, causing a voltage drop on the DC bus 25, the BATI control in the discharging direction can be started when the voltage value of the DC bus 25 falls below the DC bus voltage command value in the discharging 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 for the bidirectional DC / DC converter 24, it becomes 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 the power consumed by the load 70 and the power generated by the photovoltaic power generation module 21, etc.

[0059] (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, it 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.

[0060] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration that realizes each function can be flexibly changed.

[0061] <<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, by having the computer, etc. read and execute the program from this recording medium, the function can be provided.

[0062] 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, etc. Among such recording media, those that can be removed from a computer, etc. include, for example, flexible disks, magneto-optical disks, CD-ROMs, CD-R / Ws, DVDs, Blu-ray discs, DATs, 8mm tapes, memory cards such as flash memory, etc. Furthermore, recording media that are fixed to a computer, etc. include hard disks and ROMs, etc.

[0063] 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 load (70) of a consumer on the basis of 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) issues a control command to the first power conversion unit (22) to maintain a target value in the maximum power point tracking control before the state of charge of the storage battery (23) 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 (24), thereby cutting off the DC power supplied from the power bus (25); A power supply system (20). [Explanation of symbols]

[0064] 1. Power supply system 10 Power Conditioner (PCS) 11 Control section 12 Power conversion section 20 Distributed Power Systems (Power Systems) 21 Photovoltaic power generation module (power generation device) 22 DC / DC converter (first power conversion section) 23 Battery unit (battery) 24 Bidirectional DC / DC converter (second power conversion section) 25 DC bus (power bus) 26 Power Sensor 70 load 80 Power system 81 Power meter 101 processors 102 Main storage 103 Auxiliary storage device 104 Communication Interface 105 Input / Output Interface 106 connection bus

Claims

1. 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:

2. 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; Converting the voltage of the DC power generated by the power generation device based on a control command from the control unit a first power conversion unit that supplies the power 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.

3. 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.

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