WO2013125425A1

WO2013125425A1 - Power conversion device and direct-current system

Info

Publication number: WO2013125425A1
Application number: PCT/JP2013/053464
Authority: WO
Inventors: 亮二松井
Original assignee: シャープ株式会社
Priority date: 2012-02-22
Filing date: 2013-02-14
Publication date: 2013-08-29
Also published as: JP2013172600A

Abstract

In a direct-current system in which an electrical storage device (3) is directly coupled to a direct-current bus (1), a bidirectional DC/AC converter (40) is equipped with: a power conversion unit that converts power in a bidirectional manner between the direct-current bus (1) and system power (42); a local-path current detection unit that detects local-path current that passes through the power conversion unit; a charging/discharging current detection unit that detects charging/discharging current of the electrical storage device (3); and a control unit that controls the power conversion unit. The control unit includes: a power conversion control means for controlling power conversion in the power conversion unit in such a way that the local-path current assumes a control target value; and an adjustment means for adjusting the control target value during execution of the power conversion control means, in such a way that the detection value for the charging/discharging current stays within a predetermined current range.

Description

Power converter and DC system

The present invention relates to a power converter, and more particularly to power conversion control of a power converter applied to a DC system that supplies DC power.

In recent years, distributed power supply devices such as solar cells, wind power generators and fuel cells have begun to spread. At present, the DC power generated by the distributed power supply device is converted into AC power, and the AC power is converted into DC power and used in a device that consumes the power. Thus, since DC-AC conversion and AC-DC conversion are performed, a power loss occurs at each power conversion. Therefore, a DC system has been proposed that reduces conversion loss by transmitting DC power as it is and using it in equipment without converting the DC power generated by the distributed power supply into AC power.

As such a DC system, for example, in JP 2005-224209 A (Patent Document 1), each of a plurality of power supply units connected to a DC bus has a current control unit, and the current control unit A configuration having a function of autonomously changing a DC voltage command value or DC voltage controllability in accordance with a current input / output to / from a corresponding power supply unit is disclosed. The DC system described in Patent Document 1 allows a plurality of distributed power supplies to autonomously operate in a coordinated manner and easily add a power supply unit without depending on the device capacity.

Japanese Patent Publication “JP 2005-224209 A” Japanese Patent Publication “Japanese Patent Laid-Open No. 2003-339118”

However, in the DC system described in Patent Document 1 described above, a plurality of distributed power supplies can be autonomously operated in a coordinated manner. On the other hand, when the input / output current in each power supply unit changes, Since the control target value of the voltage of the DC bus is changed, there is a problem that the control of the entire system becomes complicated.

Further, since it is necessary to provide a power converter for each power supply unit, there is a problem that conversion loss in the power converter increases and the cost of the system increases.

In order to solve such a problem, the voltage of the DC bus is stabilized without control by directly connecting a voltage source having a high voltage stabilizing capability such as a storage battery to the DC bus without using a power converter. Is possible.

However, in the above-described configuration in which the storage battery is directly connected to the DC bus, power is directly exchanged between the DC bus and the storage battery, so that the power is exchanged between the distributed power source and / or the system power and the DC bus. Directly affected by fluctuations in power, the charge / discharge current input / output to / from the storage battery tends to fluctuate. Therefore, the charge / discharge current of the storage battery may deviate from a predetermined current range.

A storage battery normally has “allowable charging current” and “allowable discharge current” that can be passed through the storage battery according to its specifications. When a charge / discharge current exceeding the allowable charge current and the allowable discharge current flows to the storage battery, the storage battery is likely to deteriorate. Therefore, it is necessary to control the charging / discharging current of the storage battery so as not to exceed the allowable charging current and the allowable discharging current. Note that the allowable charging current and the allowable discharging current may be described as a rated current.

Furthermore, the influence of fluctuations in power transferred to and from the DC bus extends to a power conversion device that performs power conversion between the DC bus and the system power. If the power sent to or received from the DC bus fluctuates, the balance of power balance between the DC bus and the power converter may be disrupted, possibly resulting in power exceeding the rated output of the power converter. There is.

Therefore, the present invention has been made to solve such a problem, and an object thereof is to protect the power storage device in a DC system in which the power storage device is directly connected to the DC bus without using a power converter.

Another object of the present invention is to protect a power converter that converts power between the DC bus and system power in a DC system in which a power storage device is directly connected to the DC bus without a power converter.

In one aspect of the present invention, the power converter is connected to a DC bus disposed between the power storage device and the system power. The power conversion device includes a power conversion unit that converts power between a DC bus and system power, a self-path current detection unit that detects a self-path current flowing through the power conversion unit, and a charge / discharge that acquires a charge / discharge current of the power storage device A current acquisition unit and a control unit that controls the power conversion unit are provided. The control unit includes a power conversion control unit for controlling power conversion in the power conversion unit so that the self-path current becomes a control target value, and the acquired charge / discharge current is predetermined during execution of the power conversion control unit. Adjusting means for adjusting the control target value so as to be within the current range.

Preferably, the adjustment means responds to the charge / discharge current when the charge / discharge current when the power conversion control means is executed with the predetermined control target value set to an initial value exceeds a predetermined current range. During the execution of the changing means for changing the control target value and the power conversion control means using the changed control target value, the control target value is set to the initial value while controlling the charging / discharging current within a predetermined current range. And return means for returning to.

Preferably, the adjustment means responds to the charge / discharge current when the charge / discharge current when the power conversion control means is executed with the predetermined control target value set to an initial value exceeds a predetermined current range. During the execution of the change means for changing the control target value and the power conversion control means using the changed control target value, the charge / discharge current is in a state where the charge / discharge current is within a predetermined current range. Returning means for returning the control target value to the initial value when it has changed is included.

In another aspect of the present invention, the power converter is connected to a DC bus disposed between the power storage device and the system power. The power converter includes a power converter that converts power between the DC bus and the grid power, a self-path current detector that detects a self-path current that flows through the power converter, and a charge / discharge that acquires a charge / discharge current of the power storage device A current acquisition unit and a control unit that controls the power conversion unit are provided. The control unit includes a power conversion control unit for controlling power conversion in the power conversion unit so that the charge / discharge current becomes a control target value, and a detected value of the own path current is predetermined during execution of the power conversion control unit. Adjusting means for adjusting the control target value so as to be within the current range.

Preferably, the adjusting means sets the predetermined control target value as an initial value, and when the detected value of the self-path current when the power conversion control means is executed exceeds a predetermined current range, the self-path current During the execution of the change means for changing the control target value according to the detected value and the power conversion control means using the changed control target value, the detected value of the own path current is controlled within a predetermined current range. However, a return means for returning the control target value to the initial value is included.

Preferably, the adjusting means sets the predetermined control target value as an initial value, and when the detected value of the self-path current when the power conversion control means is executed exceeds a predetermined current range, the self-path current During the execution of the changing means for changing the control target value according to the detected value and the power conversion control means using the changed control target value, the detected value of the own path current falls within a predetermined current range. And a return means for returning the control target value to the initial value when the detected value of the self-path current changes.

According to another aspect of the present invention, a DC system includes a DC bus, a power storage device that outputs a power supply voltage to the DC bus, a power converter connected between the DC bus and the system power, and a power converter. A self-path current detection unit that detects a flowing self-path current and a charge / discharge current detection unit that detects a charge / discharge current of the power storage device. The power conversion device includes a power conversion unit that converts power between a DC bus and system power, and a control unit that controls the power conversion unit. The control unit includes a power conversion control unit for controlling power conversion in the power conversion unit so that the self-path current becomes a control target value, and a detection value of the charge / discharge current is predetermined during execution of the power conversion control unit. Adjusting means for adjusting the control target value so as to be within the current range.

According to another aspect of the present invention, a DC system includes a DC bus, a power storage device that outputs a power supply voltage to the DC bus, a power converter connected between the DC bus and the system power, and a power converter. A self-path current detection unit that detects a flowing self-path current and a charge / discharge current detection unit that detects a charge / discharge current of the power storage device. The power conversion device includes a power conversion unit that converts power between a DC bus and system power, and a control unit that controls the power conversion unit. The control unit includes a power conversion control unit for controlling power conversion in the power conversion unit so that the charge / discharge current becomes a control target value, and a detection value of the own path current is a predetermined value during execution of the power conversion control unit. Adjusting means for adjusting the control target value so as to be within the current range.

According to the present invention, the power storage device and the power conversion device can be protected in the DC system in which the power storage unit is directly connected to the DC bus without the power converter.

1 is a diagram schematically showing an overall configuration of a DC system to which a power conversion device according to an embodiment of the present invention is applied. FIG. It is a circuit diagram which shows the detailed structure of the bidirectional | two-way DC / AC converter in FIG. It is a figure which shows an example of the target value setting table | surface used by a bidirectional | two-way DC / AC converter. It is a figure for demonstrating the self-path current control in a bidirectional | two-way DC / AC converter. It is a figure for demonstrating the self-path current control in a bidirectional | two-way DC / AC converter. It is a figure which shows the control structure of the control part in FIG. It is the flowchart which showed the control processing procedure for implement | achieving the self-path current control of the power converter device by this Embodiment. It is a flowchart explaining the process of FIG.7 S200 and S300 further in detail. It is a flowchart explaining the example of a change of the process of step S200 and S300 of FIG. It is a figure explaining the adjustment operation of the battery current target value by a control part. It is the flowchart which showed the control processing procedure for implement | achieving battery current control of the power converter device by this Embodiment. 12 is a flowchart for explaining the processing of steps S500 and S600 of FIG. 11 in more detail. It is a flowchart explaining the example of a change of the process of step S500 and S600 of FIG. It is a figure which shows the other structural example of the direct current | flow system according to embodiment of this invention. It is a figure which shows the other structural example of the direct current | flow system according to embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

(Configuration of DC system)
FIG. 1 schematically shows an overall configuration of a DC system to which a power conversion device according to an embodiment of the present invention is applied.

Referring to FIG. 1, the DC system according to the present embodiment includes a DC bus 1, a photovoltaic power generation system 2, a power storage device 3, a grid power system 4, a DC load 5, and a battery monitoring unit 6. Prepare.

DC bus 1 supplies DC power to DC load 5. The DC load 5 is, for example, an electric device such as an air conditioner, a refrigerator, a washing machine, a television, a lighting device, or a personal computer used at home. Alternatively, it may be an electric device such as a computer, a copier or a facsimile used in an office, or an electric device such as a showcase or a lighting device used in a store. A solar power generation system 2, a power storage device 3, and a system power system 4 are connected to the DC bus 1.

In the DC system according to the present embodiment, a case will be described in which one DC bus 1, a photovoltaic power generation system 2, a power storage device 3, a grid power system 4, and one DC load 5 are provided. There is no limitation, and one or more may be used.

(Configuration of power storage device)
The power storage device 3 includes, for example, a secondary battery configured to be chargeable / dischargeable, such as a lithium ion secondary battery. The power storage device 3 is configured by connecting a plurality of battery cells in series. As an example, the power storage device 3 has a rated voltage of 400 V and a rated capacity of 4 kWh.

The power storage device 3 is “directly connected” to the DC bus 1, and exchanges DC power with the DC bus 1. Here, “directly connected” means that a power converter such as a DC / DC converter is not interposed between the DC bus 1 and the power storage device 3. Therefore, the voltage of DC bus 1 is substantially equal to the power supply voltage of power storage device 3. By adopting a configuration in which the power storage device 3 is directly connected to the DC bus 1 in this way, it is possible to suppress voltage fluctuations of the DC bus 1 due to sudden load fluctuations by utilizing the high voltage stabilization capability of the power storage device 3. It becomes.

Battery monitoring unit 6 detects the state value of power storage device 3 based on the outputs of current sensor 60, voltage sensor 62 and temperature sensor 64 provided in power storage device 3. Specifically, current sensor 60 detects charge / discharge current Ib that is inserted in DC bus 1 and input / output to / from power storage device 3, and outputs the detected value to battery monitoring unit 6. Voltage sensor 62 detects charge / discharge voltage Vb of power storage device 3 and outputs the detected value to battery monitoring unit 6. Temperature sensor 64 detects temperature Tb of power storage device 3 and outputs the detected value to battery monitoring unit 6. As described above, since a secondary battery is typically used as power storage device 3, current Ib, voltage Vb, and temperature Tb of power storage device 3 will be described below as battery current Ib, battery voltage Vb, and battery temperature Tb. Called.

Current sensor 60 detects charging current Ich to power storage device 3 as positive battery current Ib, and detects discharge current Idc from power storage device 3 as negative battery current Ib. The current sensor 60 corresponds to a “charge / discharge current detector”.

In the direct current system according to the present embodiment, power storage device 3 is directly connected to direct current bus 1, and bidirectional DC / AC converter 40 is configured by a full bridge inverter, as will be described later. By the power conversion operation of the AC converter 40, an AC component having a frequency corresponding to the frequency of the system power 42 is superimposed on the battery current Ib. The current sensor 60 detects the average value of the battery current Ib. Alternatively, the peak value of the battery current Ib may be detected.

Based on the detected value of the battery current Ib from the current sensor 60, the detected value of the battery voltage Vb from the voltage sensor 62, and the detected value of the battery temperature Tb from the temperature sensor 64, the battery monitoring unit 6 Estimate the remaining amount (SOC: State of Charge). The SOC is a percentage of the current remaining capacity with respect to the full charge capacity. For example, the battery monitoring unit 6 calculates the estimated SOC value based on the relationship between the open circuit voltage (OCV) of the power storage device 3 and the SOC. Alternatively, the estimated SOC value may be calculated sequentially based on the integrated value of the charge / discharge amount of power storage device 3. The integrated value of the charge / discharge amount can be obtained by temporally integrating the product (electric power) of the battery current Ib and the battery voltage Vb. Hereinafter, the battery current Ib, the battery voltage Vb, the battery temperature Tb, and the estimated SOC value are collectively referred to as “battery data”.

(Configuration of solar power generation system)
The solar power generation system 2 includes a solar cell 20 and a DC / DC converter 22. The solar cell 20 is composed of a crystalline solar cell, a polycrystalline solar cell, a thin film solar cell, or the like. The DC / DC converter 22 is disposed between the solar cell 20 and the DC bus 1, converts the DC power received from the solar cell 20 into a voltage, and supplies it to the DC bus 1.

The voltage conversion operation in the DC / DC converter 22 is performed by a control unit (not shown) according to the output voltage of the solar battery 20 and the voltage of the DC bus 1 (the line voltage between the positive bus PL and the negative bus NL). It is controlled according to the switching command. Specifically, when the voltage of DC bus 1 is lower than 420 V (corresponding to the power supply voltage of power storage device 3 when fully charged), DC / DC converter 22 causes solar cell 20 to follow the maximum power point ( MPPT) control. When the voltage of the DC bus 1 reaches 420V, the DC / DC converter 22 controls the solar battery 20 by switching from the maximum power point control to the control for maintaining the voltage of the DC bus 1 at 420V.

(System power system configuration)
In the configuration shown in FIG. 1, system power system 4 exchanges DC power with DC bus 1. The grid power system 4 includes a bidirectional DC / AC converter 40 and a grid power 42.

The grid power 42 is power received from an electric power company or the like (for example, AC 200V). The system power 42 is supplied from, for example, a single-phase three-phase commercial AC power system. In the single-phase three-wire commercial AC power system, the neutral wire is grounded via a resistor, and AC200V is supplied using two wires (R-phase wire RL and T-phase wire TL) other than the neutral wire. .

The bidirectional DC / AC converter 40 is connected between the DC bus 1 and the system power 42. Bidirectional DC / AC converter 40 converts the DC power received from DC bus 1 into AC power and supplies it to system power 42. Further, the bidirectional DC / AC converter 40 converts AC power received from the system power 42 into DC power and supplies it to the DC bus 1. In the DC system according to the present embodiment, system power is purchased from an electric power company or the like (power purchase) via bidirectional DC / AC converter 40, and surplus power is supplied via bidirectional DC / AC converter 40. It is configured to be able to sell (power sale) to companies.

In FIG. 1, for the current flowing through the bidirectional DC / AC converter 40 (hereinafter also referred to as “self-path current”) Iinv, the self-path current during power purchase is Ibuy, and the self-path current during power sale is Icell. Is written. Further, the current supplied to the DC load 5 is expressed as Iload, and the current supplied from the solar power generation system 2 to the DC bus 1 is expressed as Ipv. At the time of power purchase, a current obtained by subtracting the current Iload from the sum of the current Ipv and the current Ibuy becomes the charging current Ich of the power storage device 3. At the time of power sale, a current obtained by subtracting current Iload from the sum of current Ipv and discharge current Idc of power storage device 3 is current Icell. The values of the currents Isel and Ibuy can be freely set by the user or administrator of the DC system.

(Configuration of bidirectional DC / AC converter)
Next, with reference to the drawings, the configuration of bidirectional DC / AC converter 40 which is one form of the power conversion device according to the embodiment of the present invention will be described.

FIG. 2 is a circuit diagram showing a detailed configuration of the bidirectional DC / AC converter 40 in FIG.
Referring to FIG. 2, bidirectional DC / AC converter 40 includes a bidirectional inverter 400,

interconnection reactors

410 and 412, a current sensor 430, a voltage sensor 440, and a control unit 420.

The bidirectional inverter 400 converts the DC power received from the DC bus 1 into AC power and outputs it to the system power 42 in response to the switching control signals S1 to S4 from the control unit 420 at the time of power sale. Bidirectional inverter 400 converts AC power received from system power 42 into DC power and outputs it to DC bus 1 in accordance with switching control signals S 1 to S 4 from control unit 420 during power purchase.

Specifically, the bidirectional inverter 400 includes transistors Q1 to Q4, which are switching elements, and diodes D1 to D4. Transistors Q1 and Q2 are connected in series between positive bus PL and negative bus NL constituting DC bus 1. An intermediate point between transistors Q1 and Q2 is connected to R-phase line RL. Interconnection reactor 410 is connected to R-phase line RL.

Transistors Q3 and Q4 are connected in series between positive bus PL and negative bus NL. An intermediate point between transistors Q3 and Q4 is connected to T-phase line TL. Interconnected reactor 412 is connected to T-phase line TL. Between the collector and emitter of each of the transistors Q1 to Q4, diodes D1 to D4 that flow current from the emitter side to the collector side are respectively connected. Transistors Q1-Q4 and diodes D1-D4 constitute a full bridge circuit.

For example, IGBTs (Insulated Gate Bipolar Transistors) can be used as the transistors Q1 to Q4. Alternatively, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

Current sensor 430 is inserted in negative bus SL, detects a current value (own path current) Iinv of power exchanged between DC bus 1 and bidirectional inverter 400, and outputs the detection result to control unit 420. To do. The current sensor 430 corresponds to a “self-path current detection unit”.

Voltage sensor 440 is connected between positive bus PL and negative bus SL, detects voltage value Vdc of power transferred between bidirectional inverter 400 and system power 42, and outputs the detection result to control unit 420. Output. As described above, since the power storage device 3 is “directly connected” to the DC bus 1, the voltage Vdc of the DC bus 1 is equal to the battery voltage Vb. In reality, a slight voltage difference is generated between the voltage value Vd1 and the battery voltage Vb due to the wiring impedance, but it is assumed to be negligibly small in the present embodiment.

The control unit 420 includes the own path current Iinv received from the current sensor 430, the voltage Vdc received from the voltage sensor 44, the battery current Ib received from the current sensor 60, and battery data (battery voltage Vb from the battery monitoring unit 6). Based on the battery temperature Tb and the remaining battery charge SOC), the switching control signals S1 to S4 for controlling on / off of the transistors Q1 to Q4 are generated according to the control structure described later, and the bidirectional inverter 400 is controlled. To do.

Specifically, the control unit 420 sets a control target value in the bidirectional inverter 400. This control target value includes a current target value Inv * of the own path current Iinv and a current target value Ib * of the battery current Ib. In the following description, the current target value Iinv * of the own path current Iinv is also referred to as “own path current target value”, and the current target value Ib * of the battery current Ib is also referred to as “battery current target value”.

The control target values (the self-path current target value Iinv * and the battery current target value Ib *) are determined in advance so as to be different values depending on, for example, the date and time or the remaining battery level (SOC) of the power storage device 3, and are not illustrated. Can be stored in memory. FIG. 3 is a diagram illustrating an example of a target value setting table used by the bidirectional DC / AC converter 40. In the figure, as described above, the battery current is represented with the charging direction of the power storage device 3 as a positive direction and the discharge direction of the power storage device 3 as a negative direction. The self-path current Iinv is described with the power selling direction as the positive direction and the power purchase direction as the negative direction. Battery current target value Ib * includes current target value Ich * of charging current Ich and current target value Idc * of discharge current Idc. The own path current target value Iinv * includes a current target value Isel * of the own path current Isel at the time of power sale and a current target value Ibuy * of the own path current Ibuy at the time of power purchase.

Control unit 420 sets own path current target value Iinv * or battery current target value Ib * according to the date and time and the remaining battery level of power storage device 3 in accordance with the target value setting table shown in FIG. Or you may make it acquire the control target value set according to the target value setting table | surface of FIG. 3 by communicating between the control part 420 and the exterior of a DC system.

Referring to FIG. 3, for example, in the time zone from 7:00 to 17:00, when the remaining battery level (SOC) of power storage device 3 is 20% or more and less than 80%, solar power generation system 2 generates power. The self-path current target value Iinv * is set to 10 A so as to actively sell power. That is, the self-path current target value Isell * at the time of power sale is set to 10A. In this case, the control unit 420 controls the bidirectional inverter 400 by generating the switching control signals S1 to S4 so that the own path current Iinv becomes the own path current target value Iinv *.

On the other hand, in the time zone from 7:00 to 17:00, when the remaining battery level of the power storage device 3 is less than 20%, the power storage device 3 is charged with the power generated by the solar power generation system 2. The battery current target value Ib * is set to 8A. That is, current target value Ich * of charging current Ich of power storage device 3 is set to 8A. In this case, the control unit 420 controls the bidirectional inverter 400 by generating the switching control signals S1 to S4 so that the battery current Ib becomes the battery current target value Ib *.

In the following description, in order to distinguish each current control, the current control based on the own path current target value Iinv * is also referred to as “own path current control”, and the current control based on the battery current target value Ib * is “ Also referred to as “battery current control”.

(1) Self-path current control FIGS. 4 and 5 are diagrams for explaining self-path current control in bidirectional DC / AC converter 40 according to the embodiment of the present invention.

Referring to FIG. 4, it is assumed that the own path current target value Iinv * is set to −10 A according to the target value setting table shown in FIG. 3 (the current target value Ibuy * = 10 A).

In this case, the bidirectional DC / AC converter 40 performs a power conversion operation so as to purchase power with its own path current Iinv = −10 A (Ibuy = 10 A). Specifically, the bidirectional DC / AC converter 40 performs the switching operation in response to the switching control signals S1 to S4 generated according to the current deviation of the own path current Iinv with respect to the own path current target value Iinv *. The AC power received from the power 42 is converted into DC power and supplied to the DC bus 1.

Here, assuming that the output current Ipv = 5 A of the photovoltaic power generation system 2 and the current Iload = 3 A supplied to the DC load 5, the current Ipv and the current Ipv can be obtained by purchasing with the own path current Iinv = −10 A. The power storage device 3 is charged with a current obtained by subtracting the current Iload from the sum of the currents Iinv = 12 A (battery current Ib = 12 A).

On the other hand, in the power storage device 3, the range of current that can be passed through the power storage device 3 is determined due to its specifications. This current range is determined based on the rated capacity of power storage device 3, for example. In this embodiment, as an example, 1C = 10 A is set as the upper and lower limit values of the current range. That is, the battery current Ib needs to fall within the range of −10A to 10A.

However, in FIG. 4, the power storage device 3 is charged with the battery current Ib = 12 A, and a current exceeding the upper limit value 10 A of the current range flows to the power storage device 3. Thereby, there exists a possibility that the performance degradation of the electrical storage apparatus 3 may advance.

Therefore, in the present embodiment, when the battery current Ib deviates from a predetermined current range during execution of current control according to the self-path current target value Iinv *, the battery current Ib is within the current range. The own path current target value Iinv * is adjusted.

Specifically, as shown in FIG. 4, when the battery current Ib exceeds the upper limit value of the current range, the own path current target value Iinv * is changed so as to reduce the excess amount. Referring to FIG. 5, self-path current target value Iinv * in bidirectional DC / AC converter 40 is changed from −10A to −8A. That is, the current target value Ibuy * is changed from 10A to 8A. Thus, bidirectional DC / AC converter 40 performs a power conversion operation so as to purchase power with self-path current Iinv = −8 A (Ibuy = 8 A) in accordance with target path current target value Iinv * after the change. As a result, power storage device 3 is charged with current = 10 A obtained by subtracting current Iload from the sum of current Ipv and current Iinv (battery current Ib = 10 A), and battery current Ib is within the current range. Can be stored.

As shown in FIG. 4, in the DC system configured by connecting the photovoltaic power generation system 2 and the DC load 5 to the DC bus 1, the bidirectional DC / AC converter 40 sets the self-path current target value Iinv *. There is a possibility that the amount of generated power in the photovoltaic power generation system 2 or the amount of power consumed in the DC load 5 varies when the current control is executed. In such a situation, the electric power charged / discharged by the power storage device 3 fluctuates, so that the battery current Ib may be out of the current range of the power storage device 3. In the power conversion device according to the present embodiment, the self-path current target is set so that battery current Ib falls within the current range with self-path current target value Iinv * set based on the target value setting table of FIG. 3 as an initial value. Adjust the value Iinv *. Thereby, excess of battery current can be eliminated by self-path current control in the power converter. As a result, performance degradation of the power storage device 3 can be avoided.

Hereinafter, with reference to FIG. 6 to FIG. 9, the adjustment operation of the own path current target value Iinv * in the power conversion device according to the present embodiment will be described.

FIG. 6 is a diagram illustrating a control structure of the control unit 420 in FIG.
Referring to FIG. 6, control unit 420 includes a control target value generation unit 500, a switching element control signal generation unit 510, and a memory 520.

The control target value generation unit 500 generates the own path current target value Iinv ** as the control target value of the bidirectional DC / AC converter 40. As will be described later, the self-path current target value Iinv ** is set to the initial value of the self-path current target value Iinv * determined according to the target value setting table of FIG. 3, and the battery current Ib during execution of the self-path current control It corresponds to the self-path current target value after being adjusted according to.

When the switching element control signal generation unit 510 receives the own path current target value Iinv ** from the control target value generation unit 500, the switching element control signal generation unit 510 switches the switching control signals S1 to S1 so that the own path current Iinv becomes the own path current target value Iinv **. S4 is generated and the bidirectional DC / AC converter 40 is controlled.

Specifically, the switching element control signal generation unit 510 is configured to include at least a proportional element (P) and an integral element (I), and the self-path current with respect to the self-path current target value Iinv **. An operation signal is generated according to the deviation of Iinv. Then, switching element control signal generation unit 510 generates a duty command that defines the on-duty of transistors Q1 to Q4 of bidirectional inverter 400 (FIG. 2) based on this operation signal. Are generated, the switching control signals S1 to S4 are generated.

The memory 520 can read and write information, and is composed of, for example, a RAM (Random Access Memory). Memory 520 has a storage area for storing target value setting table (FIG. 3), a predetermined current range in power storage device 3, and battery data that is sequentially updated according to the specifications of power storage device 3. In this storage area, detection information of the battery current Ib transmitted from the current sensor 60 (battery current detection information) and detection information of the own path current Iinv transmitted from the current sensor 430 (own path current detection information) are further stored. Is done.

Control target value generation unit 500 receives self-path current Iinv from current sensor 430, battery current Ib from current sensor 60, and battery remaining amount (SOC) of power storage device 3 from battery monitoring unit 6. The control target value generation unit 500 generates the own path current target value Iinv ** based on the input information and the information stored in the memory 520.

6 shows an example in which the control target value generation unit 500 receives the remaining battery level of the power storage device 3 from the battery monitoring unit 6, but the control target value generation unit 500 itself detects the detection information of the battery current Ib and / or Or it is good also as a structure which estimates the battery remaining charge of the electrical storage apparatus 3 based on the detection information of the battery voltage Vb. For example, the estimated SOC value may be calculated by referring to the relationship between the OCV and the SOC of the power storage device 3 based on the detected value of the battery voltage Vb transmitted from the voltage sensor 62.

FIG. 7 is a flowchart showing a control processing procedure for realizing the self-path current control of the power conversion device according to the present embodiment. The control process according to the flowchart shown in FIG. 7 is executed by the control unit 420 at regular intervals. In addition, each step illustrated in FIG. 7 is realized by software processing and / or hardware processing by the control unit 420.

Referring to FIG. 7, control unit 420 sets current target value Iinv ** of self-path current Iinv in step S100. Specifically, control unit 420 refers to target value setting table (FIG. 3) stored in memory 520 to determine self-path current target value Iinv * based on the date and time and the remaining battery level of power storage device 3. Set. That is, the process of step S100 corresponds to the function of the control target value generation unit 500. Control unit 420 sets self-path current target value Iinv * determined according to the target value setting table (FIG. 3) as an initial value of self-path current target value Iinv **. That is, initial value Iinv * is a variable value that changes according to the date and time and the remaining battery level of power storage device 3.

Next, in step S200, control unit 420 generates switching control signals S1 to S4 so that self-path current Iinv becomes self-path current target value Iinv **, and controls bidirectional inverter 400 (current control). ).

Further, when the control unit 420 acquires the battery current Ib (battery current detection information) detected by the current sensor 60 during the power conversion operation in the bidirectional inverter 400 in step S300, the acquired battery current is acquired. Based on Ib, the self-path current target value Iinv ** is adjusted. Specifically, control unit 420 compares the current range of power storage device 3 stored in memory 520 with battery current Ib. Then, the control unit 420 adjusts the own path current target value Iinv ** based on the comparison result. The function of step S300 corresponds to the function of the control target value generation unit 500 shown in FIG.

FIG. 8 is a flowchart for explaining the processing in steps S200 and S300 in FIG. 7 in more detail.

Referring to FIG. 8, in step S01, control unit 420 compares self-path current Iinv detected by current sensor 430 with self-path current target value Iinv **. When the self-path current Iinv is smaller than the self-path current target value Iinv ** (when YES is determined in step S01), the control unit 420 performs the self-path current Iinv and the self-path current target value Iinv ** in step S02. The switching control signals S1 to S4 are generated based on the current deviation. By performing such control, the own path current Iinv changes in the positive direction (the power selling direction) (that is, the own path current Iinv increases).

On the other hand, when the self-path current Iinv is equal to or greater than the self-path current target value Iinv ** (when NO is determined in step S01), the control unit 420 performs the self-path current Iinv and the self-path current target value Iinv in step S03. Switching control signals S1 to S4 are generated based on the current deviation from **. By performing such control, the own path current Iinv changes in the negative direction (the power purchase direction) (that is, the own path current Iinv decreases). The processing in steps S01 to S03 corresponds to the processing in step S200 shown in FIG.

The control unit 420 acquires the battery current Ib (battery current detection information) from the current sensor 60 during the execution of the current control shown in S01 to S03. Then, control unit 420 determines whether or not battery current Ib is within the current range of power storage device 3. Specifically, in step S04, control unit 420 determines whether or not battery current Ib is greater than or equal to the lower limit value (eg, −10 A) of the current range. When the battery current Ib is smaller than the lower limit (when NO is determined in step S04), the control unit 420 decreases the own path current target value Iinv ** by a predetermined amount ΔI1 in step S05.

That is, when discharge current Idc is out of the current range of power storage device 3 (when NO is determined in step S04), control unit 420 causes self-path current target value Iinv to decrease self-path current target value Iinv **. Adjust **. In the bidirectional DC / AC converter 40, the power conversion operation is executed in accordance with the adjusted self-path current target value Iinv **, thereby reducing the self-path current Isel at the time of power sale while purchasing power. The self-path current Ibuy at increases. As described above, the self-path current target value Iinv ** is adjusted so that the electric power supplied from the power storage device 3 to the DC bus 1 is decreased at the time of both selling and buying power, thereby discharging the power storage device 3. The current Idc is within the current range.

On the other hand, when battery current Ib is equal to or greater than the lower limit value of the current range (when YES is determined in step S04), control unit 420 further determines that battery current Ib is the upper limit value (10A) of the current range in step S06. ) Determine whether or not: When battery current Ib is larger than the upper limit value (when NO is determined in step S06), control unit 420 increases own path current target value Iinv ** by a predetermined amount ΔI1 in step S07.

That is, when charging current Ich is out of the current range of power storage device 3 (NO determination in step S06), control unit 420 causes self-path current target value Iinv to increase self-path current target value Iinv **. Adjust **. In the bidirectional DC / AC converter 40, the power conversion operation is executed in accordance with the adjusted self-path current target value Iinv **, thereby increasing the self-path current Isel at the time of power sale while purchasing power. The self-path current Ibuy at is reduced. As described above, the self-path current target value Iinv ** is adjusted so that the power supplied from the DC bus 1 to the power storage device 3 is reduced at the time of selling and buying power, thereby charging the power storage device 3. The current Ich falls within the current range.

Thus, when the battery current Ib is out of the current range of the power storage device 3, the own path current target value Iinv ** is increased or decreased by a predetermined amount ΔI1 so that the battery current Ib is within the current range. . The predetermined amount ΔI1 is determined in consideration of the control speed of current control in the bidirectional DC / AC converter 40.

On the other hand, when the battery current Ib is equal to or lower than the upper limit value of the current range in step S06 (when YES is determined in step S06), that is, when the battery current Ib is within the current range of the power storage device 3, the control unit In step S08 to S11, 420 executes a return process for returning the own path current target value Iinv ** to the initial value Iinv *.

Specifically, the control unit 420 determines whether or not the own path current target value Iinv ** is larger than the initial value Iinv * in step S08. When own path current target value Iinv ** is larger than initial value Iinv * (when YES is determined in step S08), control unit 420 decreases own path current target value Iinv ** by a predetermined amount ΔI2 in step S09. Let

On the other hand, when the own path current target value Iinv ** is equal to or less than the initial value Iinv * (when NO is determined in step S08), the control unit 420 further performs step S10 to set the own path current target value Iinv ** to the initial value. It is determined whether it is smaller than Iinv *. When own path current target value Iinv ** is smaller than initial value Iinv * (when YES is determined in step S10), control unit 420 increases own path current target value Iinv ** by a predetermined amount ΔI2 in step S11. Let The predetermined amount ΔI2 is determined in consideration of the control speed of current control in the bidirectional DC / AC converter 40. On the other hand, when the own path current target value Iinv ** is equal to the initial value Iinv * (when NO is determined in step S10), the above-described return processing of the own path current target value Iinv ** is not performed.

The processing shown in the above steps S08 to S11 is processing for returning the own path current target value Iinv ** to the initial value Iinv * while controlling the battery current Ib within the current range. Further, the processes in steps S04 to S11 correspond to the process in step S300 shown in FIG.

As described above, control unit 420 adjusts self-path current target value Iinv ** so that battery current Ib is within the current range of power storage device 3 during execution of self-path current control. As a result, even when the electric power charged / discharged in the power storage device 3 changes due to fluctuations in the power generation amount of the solar power generation system 2 and / or the power consumption amount of the DC load 5, the current limitation in the power storage device 3 is limited. Electric power can be transferred to the DC bus 1 while complying.

(Example of change)
FIG. 9 is a flowchart for explaining a modified example of the processing in steps S200 and S300 in FIG.

Referring to FIG. 9, control unit 420 acquires battery current Ib (battery current detection information) from current sensor 60 in step S21. In step S22, control unit 420 compares the obtained battery current Ib with the battery current Ib # stored in memory 520. This battery current Ib # corresponds to the battery current Ib acquired after adjustment of the own path current target value Inv ** in step S24 described later.

When battery current Ib is equal to battery current Ib # (when YES is determined in step S22), control unit 420 performs steps S01 to S07 similar to FIG. 8 according to battery current Ib acquired from current sensor 60. The own path current target value Iinv ** is adjusted. Then, in step S24, control unit 420 obtains battery current Ib when current control is performed in accordance with adjusted self-path current target value Iinv ** and stores it in memory 520.

On the other hand, when battery current Ib is different from battery current Ib # (when NO is determined in step S22), control unit 420 changes own path current target value Iinv ** to initial value Iinv * in step S23. return. Then, control unit 420 adjusts own path current target value Iinv ** according to battery current Ib acquired from current sensor 60 through steps S01 to S07 similar to those in FIG. Further, in step S24, control unit 420 acquires battery current Ib when current control is performed in accordance with adjusted self-path current target value Iinv ** and stores it in memory 520.

In this modified example, when the current Ib charged / discharged to / from the power storage device 3 changes due to fluctuations in the power generation amount in the solar power generation system 2 and / or the power consumption amount in the DC load 5, the adjusted self-path The current target value Iinv ** is returned to the initial value Iinv * and the self-path current target value Iinv ** is adjusted again. That is, the self-path current target value Iinv ** is returned to the initial value Iinv *, triggered by a change in the battery current Ib due to an external factor different from the self-path current control.

The current range of power storage device 3 according to the present embodiment is not limited to the above example. That is, instead of the configuration in which the rated current (allowable charging / discharging current) of the power storage device 3 is set to the current range (−10A to 10A), 80% of the rated current is increased above the current range, for example, from the viewpoint of extending the battery life. You may set to a lower limit. Note that what percentage of the rated current is set to the upper and lower limit values can be arbitrarily selected according to the design concept considering the battery life.

Some power storage devices have different allowable charge currents and allowable discharge currents. Therefore, the upper limit value (for example, 3A) and the lower limit value (for example, −6A) are different depending on the specifications of the power storage device to be used. Even if it makes it, the same effect can be acquired.

(2) Battery Current Control Next, battery current control in the power conversion device according to the present embodiment will be described. The adjustment operation of the battery current target value Ib ** by the control unit 420 will be described in detail with reference to FIG.

Referring to FIG. 10, in battery current control, control target value generation unit 500 generates battery current target value Ib ** as a control target value of bidirectional DC / AC converter 40. As will be described later, the battery current target value Ib ** corresponds to the self-path current Iinv during execution of the battery current control, with the battery current target value Ib * determined according to the target value setting table of FIG. 3 as an initial value. This corresponds to the target battery current value after adjustment.

When switching element control signal generator 510 receives battery current target value Ib ** from control target value generator 500, switching element control signal generator 510 generates switching control signals S1 to S4 such that battery current Ib becomes battery current target value Ib **. Then, the bidirectional DC / AC converter 40 is controlled.

Specifically, the switching element control signal generation unit 510 generates an operation signal according to the deviation of the battery current Ib from the battery current target value Ib **, similarly to the self-path current control described above. Then, switching element control signal generation unit 510 generates a duty command that defines the on-duty of transistors Q1 to Q4 of bidirectional inverter 400 (FIG. 2) based on this operation signal. Are generated, the switching control signals S1 to S4 are generated.

In the storage area of the memory 520, a predetermined current range in the bidirectional DC / AC converter 40 is stored instead of the predetermined current range in the power storage device 3. This predetermined current range corresponds to the range of current that can be passed through the bidirectional DC / AC converter 40 due to its specifications. This current range is determined based on the rated output of the bidirectional DC / AC converter 40, for example. In the present embodiment, as an example, 15 A is set as the upper and lower limit values of the current range. That is, the self-path current Iinv needs to be within the range of −15A to 15A.

Control target value generation unit 500 receives self-path current Iinv from current sensor 430, battery current Ib from current sensor 60, and battery remaining amount (SOC) of power storage device 3 from battery monitoring unit 6. Control target value generation unit 500 generates battery current target value Ib ** based on these input information and information stored in memory 520.

FIG. 11 is a flowchart showing a control processing procedure for realizing battery current control of the power conversion device according to the present embodiment. The control process according to the flowchart shown in FIG. 11 is executed by the control unit 420 at regular intervals. Each step shown in FIG. 11 is realized by software processing and / or hardware processing by the control unit 420.

Referring to FIG. 11, control unit 420 sets current target value (battery current target value) Ib ** of battery current Ib in step S400. Specifically, control unit 420 refers to a target value setting table (FIG. 3) stored in memory 520 to set battery current target value Ib * based on the date and time and the remaining battery level of power storage device 3. To do. That is, the process of step S400 corresponds to the function of the control target value generation unit 500. Control unit 420 sets battery current target value Ib * determined according to this target value setting table (FIG. 3) as an initial value of battery current target value Ib **. That is, initial value Ib * is a variable value that changes according to the date and time and the remaining battery level of power storage device 3.

Next, in step S500, the control unit 420 generates switching control signals S1 to S4 so that the battery current Ib becomes the battery current target value Ib **, and controls the bidirectional inverter 400 (current control).

Furthermore, when the control unit 420 acquires the self-path current Iinv (self-path current detection information) detected by the current sensor 430 during execution of the power conversion operation in the bidirectional inverter 400 in step S600, the acquired The battery current target value Ib ** is adjusted based on the own path current Iinv. Specifically, the control unit 420 compares the current range of the bidirectional DC / AC converter 40 stored in the memory 520 with the own path current Iinv. Then, the battery current target value Ib ** is adjusted based on the comparison result. The function of step S600 corresponds to the function of the control target value generation unit 500 shown in FIG.

FIG. 12 is a flowchart for explaining the processing of steps S500 and S600 of FIG. 11 in more detail.

Referring to FIG. 12, in step S31, control unit 420 compares battery current Ib detected by current sensor 60 with battery current target value Ib **. When battery current Ib is smaller than battery current target value Ib ** (when YES is determined in step S31), control unit 420 performs current deviation between battery current Ib and battery current target value Ib ** in step S32. The switching control signals S1 to S4 based on the above are generated. By performing such control, the battery current Ib changes in the positive direction (charging direction) (that is, the battery current Ib increases).

On the other hand, when the battery current Ib is equal to or greater than the battery current target value Ib ** (when NO is determined in step S31), the control unit 420 determines whether the battery current Ib and the battery current target value Ib ** are set in step S33. Switching control signals S1 to S4 based on the current deviation are generated. By performing such control, the battery current Ib changes in the negative direction (discharge direction) (that is, the battery current Ib decreases). The processing in steps S31 to S33 corresponds to the processing in step S500 shown in FIG.

The control unit 420 acquires the own path current Iinv (own path current detection information) from the current sensor 430 during the execution of the current control shown in S31 to S33. Then, the control unit 420 determines whether or not the self-path current Iinv is within the current range of the bidirectional DC / AC converter 40. Specifically, in step S34, control unit 420 determines whether or not self-path current Iinv is greater than or equal to the lower limit value (eg, −15 A) of the current range. When the self-path current Iinv is smaller than the lower limit (when NO is determined in step S34), the control unit 420 decreases the battery current target value Ib ** by a predetermined amount ΔI3 in step S35.

In other words, when own path current Ibuy at the time of power purchase is out of the current range of bidirectional DC / AC converter 40 (NO in step S34), control unit 420 decreases battery current target value Ib **. The battery current target value Ib ** is adjusted so that Then, by executing the power conversion operation in bidirectional DC / AC converter 40 according to adjusted battery current target value Ib **, battery current (charging current) Ich at the time of charging is reduced in power storage device 3. On the other hand, the battery current (discharge current) Idc during discharge increases. Thus, the battery current target value Ib ** is such that the power supplied from the DC bus 1 to the power storage device 3 during charging decreases while the power supplied from the power storage device 3 to the DC bus 1 increases during discharging. Is adjusted so that the self-path current Iinv at the time of power purchase falls within the current range.

On the other hand, when the own path current Iinv is equal to or greater than the lower limit value of the current range (when YES is determined in step S34), the control unit 420 further causes the own path current Iinv to exceed the upper limit value of the current range in step S36. (15A) It is determined whether or not. When own path current Iinv is larger than the upper limit value (NO determination in step S36), control unit 420 increases battery current target value Ib ** by a predetermined amount ΔI3 in step S37.

That is, when self-path current Isel at the time of power sale is out of the current range of bidirectional DC / AC converter 40 (NO determination at step S36), control unit 420 increases battery current target value Ib **. The battery current target value Ib ** is adjusted so that Then, by executing the power conversion operation in bidirectional DC / AC converter 40 according to the adjusted battery current target value Ib **, battery current (charging current) Ich during charging increases in power storage device 3. On the other hand, the battery current (discharge current) Idc during discharge decreases. Thus, the battery current target value Ib ** is such that the power supplied from the DC bus 1 to the power storage device 3 during charging increases while the power supplied from the power storage device 3 to the DC bus 1 decreases during discharging. Is adjusted so that the self-path current Iinv at the time of power sale falls within the current range.

Thus, when the own path current Iinv is out of the current range of the bidirectional DC / AC converter 40, the battery current target value Ib ** is set to a predetermined amount so that the own path current Iinv is within the current range. Increase or decrease by ΔI3. The predetermined amount ΔI3 is determined in consideration of the control speed of current control in the bidirectional DC / AC converter 40.

On the other hand, when the own path current Iinv is equal to or lower than the upper limit value of the current range in step S36 (when YES is determined in step S36), that is, the own path current Iinv falls within the current range of the bidirectional DC / AC converter 30. If so, the control unit 420 executes a return process for returning the battery current target value Ib ** to the initial value Ib *.

Specifically, in step S38, control unit 420 determines whether or not battery current target value Ib ** is greater than initial value Ib *. When battery current target value Ib ** is larger than initial value Ib * (when YES is determined in step S38), control unit 420 decreases battery current target value Ib ** by a predetermined amount ΔI4 in step S39.

On the other hand, when battery current target value Ib ** is equal to or smaller than initial value Ib * (when NO is determined in step S38), control unit 420 further performs battery current target value Ib ** to initial value Ib * in step S40. It is determined whether it is smaller. When battery current target value Ib ** is smaller than initial value Ib * (when YES is determined in step S40), control unit 420 increases battery current target value Ib ** by a predetermined amount ΔI4 in step S41. The predetermined amount ΔI4 is determined in consideration of the control speed of current control in the bidirectional DC / AC converter 40. On the other hand, when battery current target value Ib ** is equal to initial value Ib * (when NO is determined in step S40), the above-described return processing of battery current target value Ib ** is not performed.

The processing shown in the above steps S38 to S41 is processing for returning the battery current target value Ib ** to the initial value Ib * while keeping the self-path current Iinv within the current range. Further, the processing in steps S34 to S41 corresponds to the processing in step S600 shown in FIG.

As described above, control unit 420 adjusts battery current target value Ib ** so that self-path current Iinv is within the current range of bidirectional DC / AC converter 40 during execution of battery current control. . As a result, the power exchanged between the DC bus 1 and the bidirectional DC / AC converter 40 fluctuates in response to fluctuations in the amount of power generated by the photovoltaic power generation system 2 and / or the amount of power consumed by the DC load 5. Even in this case, power can be transferred to the DC bus 1 while observing the current limitation of the bidirectional DC / AC converter 40.

(Example of change)
FIG. 13 is a flowchart for explaining a modified example of the processing of steps S500 and S600 of FIG.

Referring to FIG. 13, control unit 420 acquires own path current Iinv (own path current detection information) from current sensor 430 in step S51. Then, in step S52, control unit 420 compares acquired self path current Iinv with self path current Iinv # stored in memory 520. This own path current Iinv # corresponds to the own path current Iinv acquired after adjustment of the battery current target value Ib ** in step S54 described later.

When self-path current Iinv is equal to self-path current Iinv # (when YES is determined in step S52), control unit 420 performs self-path current Iinv acquired from current sensor 430 in steps S31 to S37 similar to FIG. The battery current target value Ib ** is adjusted according to the above. Then, in step S54, control unit 420 obtains self-path current Iinv when current control is performed according to the adjusted battery current target value Ib **, and stores it in memory 520.

In this modified example, when the current Iinv input to and output from the bidirectional DC / AC converter 40 changes due to fluctuations in the amount of power generated in the solar power generation system 2 and / or the amount of power consumed in the DC load 5, The battery current target value Ib ** after adjustment is returned to the initial value Ib *, and the battery current target value Ib ** is adjusted again. That is, the battery current target value Ib ** is returned to the initial value Ib * with the trigger that the self-path current Iinv has changed due to an external factor different from the battery current control.

Note that the current range of the bidirectional DC / AC converter 40 according to the present embodiment is not limited to the above example. That is, instead of the configuration in which the rated output of the bidirectional DC / AC converter 40 is set to the current range, for example, 80% of the rated output may be set to the upper and lower limit values of the current range. It should be noted that what percentage of the rated output is set as the upper and lower limit values can be arbitrarily selected according to the design concept in consideration of the component life. Further, the same effect can be obtained even if the upper limit value and the lower limit value are made different according to the specifications of the bidirectional DC / AC converter to be used.

(DC system configuration example)
In the above description, as an example of the DC system, the configuration in which the photovoltaic power generation system 2, the power storage device 3, the system power system 4, and the DC load 5 are connected to the DC bus 1 has been described. However, the application of the present invention is not limited to such a DC system. Specifically, the present invention can be applied as long as the power storage device 3 and the grid power system 4 are connected to at least the DC bus 1. Therefore, for example, as shown in FIG. 14, a DC system configured by connecting the photovoltaic power generation system 2, the power storage device 3, and the system power system 4 to the DC bus 1, or as shown in FIG. 15, The present invention is also applicable to a DC system configured by connecting the power storage device 3 and the system power system 4.

Further, although the solar power generation system has been described as an example of the distributed power supply device, a wind power generation device, a fuel cell, and the like may be used.

Furthermore, in the embodiment of the present invention, the bidirectional DC / AC converter that performs bidirectional power conversion between the DC bus and the system power has been described as an example of the power conversion device. DC / AC converter for converting AC power into AC power and supplying it to system power, and AC / DC converter for converting AC power received from system power into a DC bus and supplying it to the DC bus The present invention can also be applied to a conversion device.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 DC bus, 2 solar power generation system, 3 power storage device, 4 grid power system, 5 DC load, 6 battery monitoring unit, 20 solar battery, 22 DC / DC converter, 40 bidirectional DC / AC converter, 42 grid Power, 60,430 current sensor, 62,440 voltage sensor, 64 temperature sensor, 400 bidirectional inverter, 410,412 interconnection reactor, 420 control unit, 500 control target value generation unit, 510 switching element control signal generation unit, 520 memory.

Claims

A power conversion device connected to a DC bus disposed between a power storage device and system power,
A power converter that converts power between the DC bus and the grid power;
A self-path current detection unit for detecting a self-path current flowing through the power conversion unit;
A charge / discharge current acquisition unit for acquiring a charge / discharge current of the power storage device;
A control unit for controlling the power conversion unit,
The controller is
Power conversion control means for controlling power conversion in the power converter so that the self-path current becomes a control target value;
An adjustment device for adjusting the control target value so that the acquired charging / discharging current falls within a predetermined current range during execution of the power conversion control unit.
The adjusting means includes
When the power conversion control means is executed with a predetermined control target value set to an initial value, the control is performed according to the charge / discharge current when the charge / discharge current exceeds the predetermined current range. A change means for changing the target value;
A return means for returning the control target value to the initial value while controlling the charge / discharge current to the predetermined current range during execution of the power conversion control means using the control target value after the change; The power converter device of Claim 1 containing this.
The adjusting means includes
When the power conversion control means is executed with a predetermined control target value set to an initial value, the control is performed according to the charge / discharge current when the charge / discharge current exceeds the predetermined current range. A change means for changing the target value;
When the charge / discharge current is changed in a state where the charge / discharge current is within the predetermined current range during execution of the power conversion control means using the control target value after the change, the control target value The power conversion device according to claim 1, further comprising a return means for returning the value to the initial value.
A power conversion device connected to a DC bus disposed between a power storage device and system power,
A power converter that converts power between the DC bus and the grid power;
A self-path current detection unit for detecting a self-path current flowing through the power conversion unit;
A charge / discharge current acquisition unit for acquiring a charge / discharge current of the power storage device;
A control unit for controlling the power conversion unit,
The controller is
Power conversion control means for controlling power conversion in the power converter so that the charge / discharge current becomes a control target value;
An adjustment device for adjusting the control target value so that the detected value of the current path current falls within a predetermined current range during execution of the power conversion control means.
The adjusting means includes
When the detected value of the own path current when the predetermined value of the control target is set to the initial value and the power conversion control means is executed exceeds the predetermined current range, the detected value of the own path current Changing means for changing the control target value according to
In order to return the control target value to the initial value while controlling the detected value of the own path electric current to the predetermined current range during execution of the power conversion control means using the control target value after the change. The power conversion device according to claim 4, further comprising:
The adjusting means includes
When the detected value of the own path current when the predetermined value of the control target is set to the initial value and the power conversion control means is executed exceeds the predetermined current range, the detected value of the own path current Changing means for changing the control target value according to
During the execution of the power conversion control means using the control target value after the change, the detected value of the own path current has changed while the detected value of the own path current is within the predetermined current range. 5. The power conversion device according to claim 4, further comprising return means for returning the control target value to the initial value.
DC bus,
A power storage device that outputs a power supply voltage to the DC bus;
A power converter connected between the DC bus and system power;
A self-path current detector for detecting a self-path current flowing through the power converter;
A charge / discharge current detector for detecting a charge / discharge current of the power storage device;
The power converter is
A power converter that converts power between the DC bus and the grid power;
A control unit for controlling the power conversion unit,
The controller is
Power conversion control means for controlling power conversion in the power converter so that the self-path current becomes a control target value;
A DC system comprising: adjustment means for adjusting the control target value so that the detected value of the charge / discharge current falls within a predetermined current range during execution of the power conversion control means.
DC bus,
A power storage device that outputs a power supply voltage to the DC bus;
A power converter connected between the DC bus and system power;
A self-path current detector for detecting a self-path current flowing through the power converter;
A charge / discharge current detector for detecting a charge / discharge current of the power storage device;
The power converter is
A power converter that converts power between the DC bus and the grid power;
A control unit for controlling the power conversion unit,
The controller is
Power conversion control means for controlling power conversion in the power converter so that the charge / discharge current becomes a control target value;
A DC system comprising: adjustment means for adjusting the control target value so that the detected value of the self-path current falls within a predetermined current range during execution of the power conversion control means.