JP6699320B2 - Power conditioner - Google Patents

Description

  The present invention relates to a power conditioner that systematically connects electric power supplied from a photovoltaic power generation panel or the like.

In recent years, there is an electric power supply system configured to connect electric power generated by a photovoltaic power generation panel to a commercial AC electric power system (commercial power supply) by a power conditioner and supply electric power to a load device in a customer. .
In such a system, when the power generated by the photovoltaic power generation panel is smaller than the power consumption of the load device, the power generation power of the photovoltaic power generation panel and the power from the commercial power source bear the power consumption of the load device. Further, when the power generated by the photovoltaic power generation panel is larger than the power consumption of the load device, the surplus power is reversely flowed and supplied to the grid.

In addition, in the above system, there is also a system including a storage battery as a power source other than the photovoltaic power generation panel, configured to store electric power from the commercial power source and discharge the electric power when necessary.
In this case, the electric power discharged from the storage battery is system-interconnected through the power conditioner and supplied to the load device.

  Here, in general, it is not permitted to reversely flow the power output from the storage battery and supply it to the system side.

In the system including the storage battery, the electric power generated by the solar power generation panel and the electric power of the storage battery may be supplied together to the load device. At this time, for example, when the electric power generated by the solar power generation panel and the electric power of the storage battery is larger than the electric power consumption of the load device, the surplus electric power flows backward and is supplied to the commercial power source side. .. At this time, there is a possibility that the surplus power supplied to the grid by the reverse power flow includes the power of the storage battery in which the reverse power flow is not allowed.
Therefore, it is necessary to suppress the reverse power flow of the power of the power supply for which the reverse power flow is not allowed.

  In Patent Document 1, when a power supply that allows output reverse power flow and a power supply that does not allow output reverse power flow coexist, the power from the power supply that does not allow output reverse power flow is reversed. Techniques have been proposed for suppressing the tide.

  In the said patent document 1, the 1st DC/DC converter which converts the electric power supplied from a solar cell, the 2nd DC/DC converter which converts the electric power supplied from a fuel cell or a storage battery, and a 1st DC/DC converter. And a power conditioner including a DC/AC converter that converts the electric power converted by the second DC/DC converter so as to be grid-interconnectable and supplies the converted power to the load device, and a controller that controls the second DC/DC converter Is used. The solar cell that supplies power to the first DC/DC converter is a power supply that allows reverse power flow, and the fuel cell that supplies power to the second DC/DC converter is a power supply that does not allow reverse power flow. ..

  The control device controls each unit so as to suppress reverse power flow of the output of the second DC/DC converter based on the power consumed by the load device and the outputs of both the DC/DC converters. This suppresses the reverse power flow of the power of the power supply for which the reverse power flow is not allowed.

Japanese Patent No. 5452422

  In the above-mentioned conventional technique, in order to suppress the reverse flow of the output of the second DC/DC converter, control is performed using the electric power consumed by the load device. Therefore, it is necessary to detect the power consumed by the load device.

In order to detect the power consumed by the load device, for example, if the load device is composed of a plurality of devices, a sensor for detecting the power must be provided for each of the plurality of devices. .
When a large number of sensors are used to detect the power consumed by the load device, it is conceivable that an error factor increases, such as an error of each sensor being included in the detection result, and the detection accuracy thereof decreases. If the detection accuracy of the value required to suppress the reverse power flow decreases as described above, it may be impossible to appropriately suppress the reverse power flow of the power of the power supply that does not allow the reverse power flow.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power conditioner that can appropriately suppress reverse power flow of a power supply that does not allow reverse power flow. ..

  A power conditioner, which is an embodiment, is a power conditioner that supplies power to a load device in a customer by connecting it to a commercial power source, and allows reverse power flow to the commercial power source side. A first DC/DC converter for converting electric power supplied from a power source, a second DC/DC converter for converting electric power supplied from a second power source in which reverse power flow to the commercial power source is not permitted, and the commercial A power converter that is connected to a power supply and supplies the power converted by the first DC/DC converter and the second DC/DC converter to the load device; power at a power receiving point of the commercial power supply; A control unit that controls the charge/discharge power of the second power supply based on the power supplied from the first power supply to the first DC/DC converter.

  The characteristic processing performed by the power conditioner according to the above embodiment can be realized not only as a power conditioner but also as a program for causing a computer to execute the processing by each unit.

  According to the present invention, it is possible to appropriately suppress reverse power flow of power from a power supply for which reverse power flow is not allowed.

It is a block diagram which shows the structure of the solar power generation system provided with the power conditioner which concerns on 1st Embodiment. It is a block diagram which shows the principal part structure of the solar power generation system provided with the power conditioner which concerns on 2nd Embodiment. It is a flow chart which shows an example of control processing of electric power which a storage battery charges and discharges which a control part of a 2nd embodiment performs. It is the figure which showed an example of the simulation result of discharge power control of the storage battery by the power conditioner which concerns on 2nd Embodiment. It is the figure which showed the other example of the simulation result of discharge power control of the storage battery by the power conditioner which concerns on 2nd Embodiment.

[Description of Embodiments of the Present Invention]
First, the contents of the embodiment will be listed and described.
(1) A power conditioner, which is an embodiment, is a power conditioner that supplies power to a load device in a customer by connecting it to a commercial power source, and allows reverse power flow to the commercial power source side. A first DC/DC converter that converts the power supplied from the first power supply, and a second DC/DC converter that converts the power supplied from the second power supply that does not allow reverse power flow to the commercial power supply side. , A power converter that is connected to the commercial power supply and supplies the power converted by the first DC/DC converter and the second DC/DC converter to the load device, and power at a power receiving point of the commercial power supply And a control unit that controls the charging/discharging power of the second power source based on the power supplied from the first power source to the first DC/DC converter.

According to the power conditioner having the above configuration, the power supplied from the first power supply to the first DC/DC converter and the power for charging/discharging by the second power supply are controlled using the power at the power receiving point. ing. For this reason, in the case where the power discharged from the second power supply is prevented from flowing backward, even if a large number of load devices are configured, if the power at the power receiving point is detected, charging/discharging by the second power supply is performed. It is possible to control the electric power, and unlike the above-described conventional example, it is not necessary to provide a large number of sensors for each load device in order to detect the value required to suppress the reverse power flow. As a result, it is possible to accurately detect the value required for controlling the reverse power flow, and it is possible to appropriately suppress the reverse power flow of the power of the second power supply in which the reverse power flow is not allowed. That is, according to the power conditioner configured as described above, even if the load device is composed of a large number of devices, it is not necessary to detect the power of each of the plurality of load devices, and the power of the power receiving point where the commercial power source is drawn is detected. This can be done, and more direct control becomes possible. As a result, it is possible to properly suppress reverse power flow of the power of the second power supply, which is not allowed to flow backward.
Further, according to the power conditioner configured as described above, the reverse power flow can be controlled by detecting the power supplied to the first DC/DC converter from the first power source in addition to the power at the power receiving point. It is not necessary to provide a sensor or the like for detecting the power that the DC converter gives to the power converter. As a result, with a simple configuration, it is possible to appropriately suppress the reverse power flow of the power of the second power supply, which is not allowed the reverse power flow.

(2) In the above power conditioner, when the control unit sets the power at the power receiving point as Pg_s and the power supplied from the first power source to the first DC/DC converter as Ppv_s, the following formula (1) is obtained. It is preferable to control the value on the left side of the equation (1) so as to satisfy the condition, and control the charging/discharging power by the second power supply.
Pg_s−Ppv_s<k×Pbat_s_max (1)
However, Ppv_s≠Ppv_s_max and Ppv_s_max are the rated power of the photovoltaic power generation panel 2, k is a constant, and Pbat_s_max is the rated power of the second power supply. Further, Pg_s is positive in the reverse flow direction, and Ppv_s is positive in the direction in which power is supplied from the first power supply to the first DC/DC converter.

(3) Further, it is preferable that the control unit further controls the charge/discharge power of the second power supply so as to satisfy the following expression (2).
−m≦Pg_s−Ppv_s (2)
However, m is a constant

  In this case, if the above expressions (1) and (2) are not satisfied, the control unit can determine that the electric power supplied from the second power source is reversely flowing, and the power of the second power source is reversely flowing. Can be suppressed more appropriately.

(4) Moreover, when the power conditioner further includes a switch device that opens and closes an electric path between the second power source and the second DC/DC converter, the control unit sets the control unit to the expression (1). The switch device may be configured to be opened when a state in which the above condition is not satisfied continues for a predetermined period.
In this case, if the control unit determines that the electric power discharged from the second power supply is flowing backward due to not satisfying the above equation (1), it may open the switch device to disconnect the second power supply. Therefore, it is possible to reliably suppress reverse power flow of the second power source.

(5) In the power conditioner, the control unit may be configured to control the second DC/DC converter to control the charge/discharge power of the second power supply. In this case The controller controls the output of the second DC/DC converter based on the power at the power receiving point and the power supplied from the first power source to the first DC/DC converter, and the power of the second power source is reverse flow. Can be appropriately suppressed.

[Details of Embodiment of Present Invention]
Hereinafter, preferred embodiments will be described with reference to the drawings.
Note that at least a part of the embodiments described below may be arbitrarily combined.
[Regarding the first embodiment]
FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system including a power conditioner according to the first embodiment. The solar power generation system 1 includes a solar power generation panel 2, a storage battery 3, and a power conditioner 4 to which the solar power generation panel 2 and the storage battery 3 are connected.

The photovoltaic power generation panel 2 is installed, for example, in a fixed state on the roof surface of a building or the like, and receives sunlight to generate power. The photovoltaic power generation panel 2 outputs the generated DC power to the power conditioner 4 (hereinafter, also referred to as PCS4).
Storage battery 3 outputs the stored DC power to PCS 4. In addition, the storage battery 3 can store electric power supplied from the AC power supply 5 or the photovoltaic power generation panel 2 via the PCS 4.

  The PCS 4 is connected to the AC power source 5, which is a commercial power source. The PCS 4 has a function of connecting the solar power generation panel 2 and the storage battery 3 to a commercial power source and outputting the electric power supplied from the solar power generation panel 2 and the storage battery 3.

The AC power supply 5 and the PCS 4 are connected via the electric line 10. A distribution board 11 and a load device 13 inside the customer, which is connected to a branch path 12 branched from the distribution board 11 by the distribution board 11, are connected to the distribution path 10.
Further, a first power sensor 21 as a power receiving point of the commercial power source is connected between the distribution board 11 and the AC power source 5.

The load device 13 is connected to the AC power supply 5 via the electric path 10 and the branch path 12. The load device 13 is composed of a plurality of devices that consume power.
The distribution board 11 guides the AC power from the AC power supply 5 to the load device 13, and also guides the power generated by the photovoltaic power generation panel 2 output from the PCS 4 and the power discharged by the storage battery 3 to the load device 13. ..
The PCS 4 is grid-connected to a commercial power supply and supplies power to the load device 13 to which power is supplied from the AC power supply 5.
Further, the PCS 4 also has a function of supplying AC power from the AC power supply 5 to the storage battery 3.

  The PCS 4 includes a first DC/DC converter 15 that converts the voltage of the DC power output by the photovoltaic power generation panel 2 into a predetermined voltage, and a first DC/DC converter 15 that converts the voltage of the DC power output by the storage battery 3 by discharging to a predetermined voltage. The two DC/DC converters 16 and an inverter (power converter) 17 for converting the DC power output from the DC/DC converters 15 and 16 to the DC bus 14 into AC power. The inverter 17 and the second DC/DC converter 16 are both bidirectional and can also perform inverse conversion.

  The PCS 4 converts the DC power from the photovoltaic power generation panel 2 and the storage battery 3 into AC power by the DC/DC converters 15 and 16 and the inverter 17, and supplies the AC power to the load device 13 via the electric path 10. . In this way, the PCS 4 can connect the photovoltaic power generation panel 2 and the storage battery 3 to the commercial power source of the AC power source 5.

  The PCS 4 includes a control unit 20 having a function of controlling each unit of the PCS 4. The control unit 20 includes a processor and a microcomputer including a storage unit such as a ROM and a RAM. The storage unit stores various computer programs for realizing the functions of the control unit 20. By executing these computer programs, the control unit 20 realizes a function of executing processing described below.

  The control unit 20 controls the DC/DC converters 15 and 16 and the inverter 17 according to the power of the AC power supply 5, the power generation status of the photovoltaic power generation panel 2, and the power supply status of the storage battery 3, and controls the load device 13. Electric power is supplied and electric power is supplied to the storage battery 3.

When the power generated by the photovoltaic power generation panel 2 output from the first DC/DC converter 15 is smaller than the power consumption of the load device 13, the control unit 20 controls the power generated by the photovoltaic power generation panel 2 and the power generated by the AC power supply 5. And control each unit so as to bear the power consumption of the load device 13.
Further, when the power generated by the photovoltaic power generation panel 2 is larger than the power consumption of the load device 13, the control unit 20 controls the excess power to flow backward and supply the excess power to the grid side.
Further, the control unit 20 supplies the electric power of the AC power supply 5 to the storage battery 3 during a time period such as night when the photovoltaic power generation panel 2 does not generate power, and during a time period when the power consumption of the load device 13 during the daytime increases. In the above, it is possible to control so that the electric power stored in the storage battery 3 is discharged and the electric power is supplied to the load device 13.

By the way, if the electric power stored in the storage battery 3 is the electric power supplied from the AC power supply 5, it may not be preferable to reverse-flow and supply the electric power to the commercial power supply side. That is, the electric power once purchased from the electric power company is sold again to the same electric power company, which may cause an unfavorable situation in the preset relationship between the selling price and the purchase price of the electric power. Therefore, in general, reverse power flow is allowed for the power generated by the photovoltaic power generation panel 2, but reverse power flow is not allowed for the power discharged by the storage battery 3.
That is, in the present embodiment, reverse power flow is allowed for the generated power (output) of the photovoltaic power generation panel 2, and reverse power flow is not allowed for the power (output) of the storage battery 3.

The control unit 20 may supply the load device 13 with electric power generated by the photovoltaic power generation panel 2 and electric power generated by discharging the storage battery 3. At this time, if the total power of the power generated by the photovoltaic power generation panel 2 and the power generated by the discharge of the storage battery 3 becomes larger than the power consumption of the load device 13, the surplus power at that time flows backward and the commercial power source side Will be supplied to.
In this case, the surplus electric power that flows backward and is supplied to the commercial power source side includes electric power generated by discharging the storage battery 3.

  For this reason, the control unit 20 has a function of controlling electric power due to charging and discharging of the storage battery 3 and suppressing reverse flow of the electric power discharged by the storage battery 3 to the commercial power source side.

  The control unit 20 controls the charge/discharge power of the storage battery 3 based on the power at the power receiving point of the commercial power supply and the power supplied from the solar power generation panel 2 to the first DC/DC converter 15, and the storage battery 3 Prevents the discharged power from flowing backward.

The control unit 20 acquires the power at the power receiving point of the commercial power source from the first power sensor 21 connected to the electric path 10.
The first power sensor 21 is connected to the control unit 20 so that the detection result can be given to the control unit 20.

Further, the control unit 20 supplies the electric power supplied from the solar power generation panel 2 to the first DC/DC converter 15 to the second power connected between the solar power generation panel 2 and the first DC/DC converter 15. It is acquired from the sensor 22.
The second power sensor 22 detects the power input from the photovoltaic power generation panel 2 to the first DC/DC converter 15. The second power sensor 22 is connected to the control unit 20 so that the detection result can be given to the control unit 20.

In addition, the control unit 20 supplies the power supplied from the storage battery 3 to the second DC/DC converter 16 or the power in the opposite direction to the third power connected between the storage battery 3 and the second DC/DC converter 16. It is acquired from the sensor 23.
The third power sensor 23 detects the power transferred between the storage battery 3 and the second DC/DC converter 16. The third power sensor 23 is connected to the control unit 20 so that the detection result can be given to the control unit 20.

The control unit 20 controls the charging/discharging power of the storage battery 3 based on the detection results provided from the sensors 21, 22, and 23.
In FIG. 1, arrow K indicates the positive direction of the current between the photovoltaic power generation panel 2 and the second power sensor 22. The arrow L indicates the positive direction of the current between the storage battery 3 and the third power sensor 23. The arrow M indicates the positive direction of the current between the first power sensor 21 and the load device 13. The arrow N indicates the positive direction of the current between the first power sensor 21 and the commercial power supply.

  Hereinafter, the control of the charge/discharge power by the storage battery 3, which is executed by the control unit 20, will be described.

In the present embodiment, when the total power of the power at the power receiving point and the power consumed by the load device 13 is equal to the power supplied by the PCS 4, the following expression (A) is established.
Pbat_s + Ppv_s = Pg_s + PL_s (A)

Note that Pbat_s is electric power (output of the third electric power sensor 23, which is a control value) detected between the storage battery 3 and the second DC/DC converter 16, and is positively charged in the discharging direction of the storage battery 3. The direction is negative. Ppv_s is the electric power detected between the photovoltaic power generation panel 2 and the first DC/DC converter 15 (the output of the second power sensor 22 and the measured value), and is the photovoltaic power generation panel 2 and the first DC/DC conversion. The direction in which power is supplied to the device 15 is positive. Pg_s is the power at the power receiving point (the output of the first power sensor 21, which is a measured value), and the direction in which the current flows to the commercial power source (the direction in which the current flows backward) is positive, and the opposite is negative. PL_s is the power consumed by the load device 13.
Further, Ppv_s≠Ppv_s_max and Ppv_s_max are the rated power of the photovoltaic power generation panel 2.

Further, when the total power of the commercial power and the power consumed by the load device 13 is equal to the power supplied by the PCS 4, the discharged power of the storage battery 3 is prevented from exceeding the power consumed by the load device 13. Since it is necessary, the relationship between Pbat_s and PL_s needs to satisfy the following expression (B) in addition to the above expression (A).
Pbat_s−PL_s≦k×Pbat_s_max (B)

  Note that k is a constant, and according to the regulations, the constant k is set to, for example, 0.05. It is preferable that the constant k is set to a value smaller than the maximum value, with the maximum value being a value determined by regulation. Pbat_s_max is the rated power of the storage battery 3. Therefore, k×Pbat_s_max is a fixed value.

Further, by substituting the above equation (A) into the above equation (B), the following equation (1) is obtained.
Pg_s−Ppv_s<k×Pbat_s_max (1)

If the control unit 20 controls the charge/discharge power of the storage battery 3 so as to satisfy the above formula (1), the PCS 4 prevents the discharge power of the storage battery 3 from exceeding the power consumed by the load device 13. It is possible to perform control between the power supplied and the power consumed by the load device 13.
That is, the control unit 20 can determine that the discharge power of the storage battery 3 is flowing backward when the above expression (1) is not satisfied.
As a result, the control unit 20 suppresses the discharge power of the storage battery 3 from flowing backward to the commercial power source side based on the determination result.

The control by the control unit 20 is performed by controlling the electric power charged and discharged by the storage battery 3.
The control unit 20 is independent of the control of the charging/discharging power of the storage battery 3, and the first DC/DC converter based on the detection result of the power generated by the photovoltaic power generation panel 2 and the detection result of the power flowing through each unit, the setting from the outside, and the like. 15 and the inverter 17 are controlled to control the flow of power generated by the photovoltaic power generation panel 2 and the power output as the PCS 4.

  The control unit 20 controls the second DC/DC converter 16 according to the value on the left side of the above expression (1) to control the charge/discharge power of the storage battery 3 so as to satisfy the above expression (1). ..

For example, when the value on the left side of the above formula (1) is smaller than the value on the right side, the control unit 20 controls the second DC/DC converter 16 to discharge the storage battery 3.
On the contrary, when the value on the left side of the above formula (1) is larger than the value on the right side, the control unit 20 controls the second DC/DC converter 16 so that the storage battery 3 stores electricity.
By controlling the second DC/DC converter 16 as described above, the control unit 20 controls the electric power for charging/discharging by the storage battery 3 so as to satisfy the above formula (1).

  As described above, the PCS 4 according to the present embodiment is based on the equation (1), Pg_s (output of the first power sensor 21) which is the power at the power receiving point of the commercial power source, the solar power generation panel 2, and the first DC/DC. Using Ppv_s (output of the second power sensor 22) which is the power flowing between the DC converter 15 and the charging/discharging power of the storage battery 3, the power discharged by the storage battery 3 is prevented from flowing backward. Is configured to. Therefore, if the electric power at the power receiving point is detected, the electric power for charging/discharging by the storage battery 3 can be controlled, and as in the above-mentioned conventional example, in order to detect the value required to suppress the reverse flow, the load It is not necessary to provide a large number of sensors for each of the plurality of devices making up the device 13. As a result, it is possible to accurately detect the value required for controlling the reverse flow, and it is possible to appropriately suppress the reverse flow of the electric power of the storage battery 3 in which the reverse flow is not allowed.

That is, according to the PCS 4 of the present embodiment, even if the load devices 13 are composed of a large number, it is not necessary to detect the power of each of the load devices 13, and the power of the power receiving point that is pulling in the commercial power supply is not detected. It suffices to detect it, and more direct control becomes possible. As a result, it is possible to appropriately suppress the reverse flow of the electric power of the storage battery 3 in which the reverse flow is not permitted.
Furthermore, according to the PCS 4 of the present embodiment, in addition to the power at the power receiving point (the output of the first power sensor 21), the power supplied from the photovoltaic power generation panel 2 to the first DC/DC converter 15 (the second power sensor). The reverse power flow can be controlled by detecting (output of 22), and it is not necessary to provide a sensor or the like for detecting the electric power that the first DC/DC converter 15 gives to the inverter 17. As a result, with a simple configuration, it is possible to appropriately suppress the reverse flow of the electric power of the storage battery 3, which does not allow the reverse flow.

  Further, when the above expression (1) is not satisfied, the control unit 20 of the present embodiment can determine that the power supplied from the storage battery 3 is reversely flowing, so the power of the storage battery 3 is reversely flowing. Can be suppressed more appropriately.

  Further, the control unit 20 is configured to control the second DC/DC converter 16 to control the flow of the electric power supplied from the storage battery 3 so as to satisfy the above expression (1). The output of the second DC/DC converter 16 is controlled based on the electric power at the point and the electric power supplied from the photovoltaic power generation panel 2 to the first DC/DC converter 15, so that the electric power of the storage battery 3 reversely flows. It can be suppressed appropriately.

In the above formula (1), the value on the left side is ideally preferably "0" or more, but for example, the charge/discharge power of the storage battery 3 is controlled so as to satisfy the following formula (2). You may.
−m≦Pg_s−Ppv_s (2)

However, m is a constant and indicates an allowable value when the difference between Pg_s and Ppv_s takes a negative value.
As described above, the difference between Pg_s and Ppv_s is performed by controlling the charging/discharging power of the storage battery 3, but it is not directly controlled, and therefore some errors and delays occur. The m is set to a value that can mitigate such errors and delays.

[Second Embodiment]
FIG. 2 is a block diagram showing a main configuration of a photovoltaic power generation system including a power conditioner according to the second embodiment.
In the present embodiment, the switch device 30 is connected between the storage battery 3 and the third power sensor 23, and the control unit 20 controls the switch device 30 to control the charge/discharge power of the storage battery 3. The point is different from the first embodiment.

  The switch device 30 has a function of opening and closing between the storage battery 3 and the second DC/DC converter 16 by performing an on/off operation. The switch device 30 includes a first switch 30a, a second switch 30b connected in parallel to the first switch 30a, and a resistance element 30c connected in series to the second switch 30b.

The first switch 30a is configured by connecting a pair of semiconductor switch elements 30a3 and 30a4 to which parallel diodes 30a1 and 30a2 are connected in series in mutually opposite directions. The semiconductor switch elements 30a3 and 30a4 are, for example, IGBTs (Insulated Gate Bipolar Transistors), and parallel diodes 30a1 and 30a2 are connected in reverse polarity.
The second switch 30b is also similar to the first switch 30a, and is configured by serially connecting a pair of semiconductor switch elements 30b3 and 30b4 to which the parallel diodes 30b1 and 30b2 are connected in opposite directions.

  The semiconductor switch elements 30a3, 30a4, 30b3, 30b4 are controlled by a control signal supplied from the control unit 20. As a result, the first switch 30a and the second switch 30b are turned on/off based on the control signal from the control unit 20.

  When the switch device 30 receives a control signal for connecting the storage battery 3 and the second DC/DC converter 16 in a state where the storage battery 3 and the second DC/DC converter 16 are opened, Of the first switch 30a and the second switch 30b that are both off, only the second switch 30b is turned on. A resistance element 30c is connected in series to the second switch 30b, and a rush current flows in the electric path connected to the second switch 30b, but the electric current is limited so as not to flow above a certain current.

After that, the switch device 30 connects the storage battery 3 and the second DC/DC converter 16 by turning on the first switch 30a.
Since the switch device 30 connects the storage battery 3 and the second DC/DC converter 16 as described above, the current flowing between the storage battery 3 and the second DC/DC converter 16 is increased stepwise. Therefore, a large inrush current can be prevented from flowing in the circuit.

FIG. 3 is a flowchart showing an example of a control process of the electric power charged and discharged by the storage battery 3, which is executed by the control unit 20 of the present embodiment.
First, as an initial state, the control unit 20 closes the switch device 30 and sets Pg_s, Ppv_s, and Pbat_s so as to satisfy the following equations (3) and (4) (step S1).
Pg_s−Ppv_s<k1×Pbat_s_max (3)
Pbat_s=0 (4)
In addition, in Formula (3), k1 has shown the value of the above-mentioned constant k. The value k1 is set to a value smaller than the value defined by the regulation as the constant k.

  Next, the control unit 20 controls the power Pg_s of the commercial power supplied from the first power sensor 21, and the power Ppv_s flowing between the solar power generation panel 2 and the first DC/DC converter 15 supplied from the second power sensor 22. Is acquired (step S2).

The control unit 20 determines whether or not the following expression (5) is satisfied based on the acquired electric powers Pg_s and Ppv_s (step S3).
-M <Pg_s-Ppv_s
<k1×Pbat_s_max (5)
In the formula (5), m is the constant described in the formula (2).

The control unit 20 determines whether or not the power of the storage battery 3 is reversely flowing, depending on whether or not the above expression (5) is satisfied.
When determining that the above expression (5) is satisfied, the control unit 20 returns to step S2 again and repeats steps S2 and S3. That is, when determining that the above expression (5) is satisfied, the control unit 20 determines that the power of the storage battery 3 is not reversely flowing, and maintains the current state.

On the other hand, when determining that the above expression (5) is not satisfied, the control unit 20 proceeds to step S4 and determines whether or not the following expression (6) is satisfied based on the acquired electric powers Pg_s and Ppv_s. Yes (step S4).
-M <Pg_s-Ppv_s
<k2×Pbat_s_max (6)
However, k2> k1

When determining that the above expression (6) is satisfied, the control unit 20 proceeds to step S5 to control the second DC/DC converter 16 so that the charging/discharging power of the storage battery 3 is obtained by the above expression (5). The value is set to satisfy the above condition (step S5), the process returns to step S2, and the same process as above is repeated. As a result, the control unit 20 controls the second DC/DC converter 16 to prevent reverse power flow of the power of the storage battery 3.
Here, in Expression (6), k2 represents the value of the above-mentioned constant k. The value k2 is set to a value defined by regulation as the constant k.
That is, when the equation (5) is not satisfied, the control unit 20 controls the second DC/DC converter 16 to charge and discharge the storage battery 3 if the constant k satisfies the equation (6) with the value k2. Adjust the power.

  As described above, the determination using the expression including the constant k is performed stepwise using the expressions having different values of the constant k (k1 or k2) to determine whether the power of the storage battery 3 is reversely flowing. The judgment is set in a direction in which the reverse flow of the electric power of the storage battery 3 does not occur as much as possible, and the judgment of whether to adjust the charging/discharging electric power of the storage battery 3 can be set to a wide allowable range. The degree of freedom can be increased.

  On the other hand, when determining that the above equation (6) is not satisfied, the control unit 20 proceeds to step S6, and repeats the period T (or the number of repetitions) when it is determined that the equation (6) is not satisfied in step S4. ) Is timed (counted), and it is determined whether or not the period T (the number of repetitions) exceeds a predetermined time (whether or not it exceeds the predetermined number) (step S6).

  When it is determined in step S6 that the period T has not exceeded the predetermined time and the condition repeatedly determined that the equation (6) is not satisfied in step S4 does not continue for the predetermined time, the control unit 20 determines that Returning to step S2, steps S2 to S6 are executed again.

  When it is determined in step S6 that the period T exceeds the predetermined time and the condition repeatedly determined that the equation (6) is not satisfied in step S4 continues for the predetermined time, the control unit 20 proceeds to step S7. Then, the switch device 30 is opened (step S7).

  As described above, when the control unit 20 determines that the formula (6) is not satisfied in step S4, the control unit 20 determines that the electric power discharged from the storage battery 3 is flowing backward beyond the controllable range, and the step S4 is performed. Then, the switch device 30 is opened after waiting for a predetermined time to continue the state in which it is repeatedly determined that the formula (6) is not satisfied.

  Accordingly, the control unit 20 opens the switch device 30 when it is determined that the electric power discharged from the storage battery 3 is reversely flowing for a predetermined period because the above expression (6) is not satisfied. Since the storage battery 3 is disengaged in the above manner, it is possible to reliably prevent the power of the storage battery 3 from flowing backward.

FIG. 4 is a diagram showing an example of a simulation result of discharge power control of the storage battery 3 by the power conditioner according to the second embodiment.
In FIG. 4, the control when the power of the photovoltaic power generation panel 2 is 0 kW, the discharge power (current) from the storage battery 3 is 1 kW, and the power consumption of the load device 13 is changed from 1 kW to 0.5 kW The change of the discharge electric power (current) from the storage battery 3 which the part 20 controls is shown.

  In FIG. 4, the current value of the commercial power source, the value of the tidal current, the current value of the load device 13 (load current), and the discharge current from the storage battery 3 are shown in order from the top. The horizontal axis represents time, and the timings are shown so that the values correspond to each other.

In FIG. 4, the load current fluctuation start point indicates when the power consumption of the load device 13 is changed from the state of 1 kW to 0.5 kW. In FIG. 4, the load current has a smaller amplitude after the load current fluctuation start point, which means that the load current fluctuates in the decreasing direction.
Further, in FIG. 4, it is understood that the tidal current is in a reverse phase with respect to the commercial power source in the square mark H1 which is the timing after the load current fluctuation start point, and the reverse tidal current is generated.
The reverse flow in this case is generated to the extent that the control unit 20 determines that the equation (5) is not satisfied but the equation (6) is satisfied.

  In FIG. 4, the peak value of the discharge current from the storage battery 3 decreases from the broken line P1 to the alternate long and short dash line P2 in the square mark H2 which is the timing after the square mark H1.

  As described above, when the control unit 20 of the PCS 4 of the present embodiment determines that the discharge power from the storage battery 3 is reversely flowing (step S3 in FIG. 3), if the above expression (6) is satisfied (FIG. 3, step S4) controls the second DC/DC converter 16 to adjust the charging/discharging power (current) of the storage battery 3 so as to satisfy the above equation (5) (step S5 in FIG. 3).

FIG. 5: is the figure which showed the other example of the simulation result of the discharge power control of the storage battery 3 by the power conditioner which concerns on 2nd Embodiment.
Also in FIG. 5, when the power of the photovoltaic panel 2 is 0 kW, the discharge power (current) from the storage battery 3 is 1 kW, and the power consumption of the load device 13 is changed from the state of 1 kW to 0.5 kW, The change of the discharge electric power (current) from the storage battery 3 which the control part 20 controls is shown.

In FIG. 5 as well, the load current has a smaller amplitude after the load current fluctuation start point, and it is shown that the load current fluctuates in the decreasing direction.
Further, it can be seen that the tidal current is in a reverse phase with respect to the commercial power source after the load current fluctuation start point, and a reverse tidal current is generated.
The reverse flow in this case occurs to the extent that the control unit 20 determines that the above equations (5) and (6) are not satisfied.

In FIG. 5, the peak value of the discharge current from the storage battery 3 decreases from a constant value to 0 within the square mark H3.
Further, the period between the timing when the discharge current is 0 and the load current fluctuation start point is the period T when it is repeatedly determined that the equation (6) is not satisfied in step S4 in FIG. In the case of FIG. 5, it is set to 240 ms, for example.

  As described above, the control unit 20 of the PCS 4 according to the present exemplary embodiment determines that the state in which it is repeatedly determined that the equation (6) is not satisfied in step S4 is continued for the predetermined time (step in FIG. 3). S6), the switch device 30 is opened (step S7), and the reverse flow of the electric power of the storage battery 3 is suppressed.

  From the above simulation result, it can be confirmed that the control unit 20 of the PCS 4 of the present embodiment can appropriately suppress the reverse flow of the power of the storage battery 3 for which the reverse flow is not allowed.

[Other]
It should be understood that the embodiments disclosed this time are exemplifications in all points and not restrictive.

In each of the above-mentioned embodiments, the case where the photovoltaic power generation panel 2 constitutes the first power source in which the reverse power flow of the output is permitted and the storage battery 3 constitutes the second power source in which the reverse power flow of the output is not permitted. Although illustrated, it is not limited thereto.
For example, a power supply that generates power using renewable energy can be adopted as a power supply that allows output reverse flow. As a power source for generating power using renewable energy, in addition to the solar power generation panel shown in each of the above-described embodiments, a power source for generating power using wind power generation, wave power, tidal power, running water, geothermal power, etc. can be considered. .
In addition to the storage battery, a fuel cell or the like is conceivable as the power source in which the reverse flow of the output is not allowed.

  The scope of the present invention is defined by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1 Solar power generation system 2 Solar power generation panel 3 Storage battery 4 Power conditioner 5 AC power supply 10 Electric line 11 Distribution board 12 Branching line 13 Load device 14 DC bus 15 First DC/DC converter 16 Second DC/DC converter 17 Inverter 20 control part 21 1st power sensor (power receiving point) 22 2nd power sensor 23 3rd power sensor 30 switch device 30a 1st switch 30a1 parallel diode 30a2 parallel diode 30a3 semiconductor switch element 30a4 semiconductor switch element 30b 2nd switch 30b1 parallel diode 30b2 Parallel diode 30b3 Semiconductor switching element 30b4 Semiconductor switching element 30c Resistance element

Claims (6)

A power conditioner that supplies power to a load device in a customer by connecting it to a commercial power source,
A first DC/DC converter that converts electric power supplied from a first power source that allows reverse power flow to a commercial power source side;
A second DC/DC converter for converting the electric power supplied from the second power source whose reverse power flow to the commercial power source side is not allowed to exceed a predetermined reference value ;
A switch device for opening and closing an electric path between the second power source and the second DC/DC converter;
Said commercial power source to and interconnection, a power converter for supplying electric power the first 1D C / DC converter and the second 2DC / DC converter is converted to the load device,
It includes a power receiving point of the commercial power supply, on the basis of the electric power supplied from the first power source to the first 1 DC / DC converter, and a control unit for controlling the power of charging and discharging by the second power supply ,
The control unit opens the switch device when the state in which the reverse flow caused by the electric power supplied from the second power source is equal to or higher than the reference value continues for a predetermined period . When the power of the power receiving point is Pg_s and the power supplied from the first power source to the first DC/DC converter is Ppv_s, the control unit satisfies the following formula (1) so as to satisfy the following formula (1). The power conditioner according to claim 1, wherein the value of the left side of the power conditioner is controlled to control the charge/discharge power of the second power supply.
Pg_s−Ppv_s<k×Pbat_s_max (1)
However, Ppv_s≠Ppv_s_max and Ppv_s_max are the rated power of the photovoltaic power generation panel 2, k is a constant, and Pbat_s_max is the rated power of the second power supply. Further, Pg_s is positive in the reverse flow direction, and Ppv_s is positive in the direction in which power is supplied from the first power supply to the first DC/DC converter. The power conditioner according to claim 2, wherein the control unit further controls the charge/discharge power of the second power supply so as to satisfy the following expression (2).
−m≦Pg_s−Ppv_s (2)
However, m is a constant Prior Symbol controller, the state does not satisfy the above formula (1) is continued for a predetermined period of time, the power conditioner according to claim 2, open the switch device.   The power conditioner according to any one of claims 1 to 4, wherein the control unit controls the second DC/DC converter to control the power for charging/discharging by the second power supply.   The control unit is
    When the reference value is the first reference value, the reverse flow due to the electric power supplied from the second power source is below the second reference value which is a reference value smaller than the first reference value. Controls the charging/discharging power from two power sources,
    When the reverse power flow due to the electric power supplied from the second power source is equal to or higher than the second reference value, the reverse flow may be lower than the second reference value depending on whether the reverse flow is equal to or higher than the first reference value. The process of controlling the charging/discharging power of the second power source and the process of opening the switch device when a state of being equal to or higher than the first reference value continues for a predetermined period are selectively executed. Indicated power conditioner.