JP2013005658A - Power conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conditioner which can operate a direct-current load efficiently and stably.SOLUTION: The power conditioner comprises: a bidirectional inverter 12 which selectively executes DC/AC conversion to convert a direct-current output based on power generation from a power generation facility 21 to an alternating current, or AC/DC conversion to convert an alternating current from a system 22 to a direct current; a system linked switch 13 which connects the bidirectional inverter 12 to the system 22; a rectifier unit 14 connected to the system side of the system linked switch 13, which rectifies an alternating current from the system 22; a DC output switch 16 which feeds one of the direct-current output based on power generation from the power generation facility 21, the direct-current output of the bidirectional inverter 12 and the rectified output of the rectifier unit 14 to a direct-current load; a storage unit 17 which stores operation modes therein in which mode power is fed to the direct-current load; and a control unit 18 which controls the system linked switch 13 and the DC output switch 16 according to an operation mode and also chooses which power, the direct-current output or the rectified output, to feed to the DC output switch 16.

Description

  The present invention relates to a power conditioner that links a power generation facility and a commercial power supply system (system).

  A power generation system including a power generation facility such as a solar panel includes a power conditioner for connecting the power generation facility and the system. As such a power conditioner, it is equipped with a direct current output unit for the storage battery, and the storage battery is charged by the power from the power generation equipment and the system, and when a system abnormality such as a power failure or a decrease in the system voltage occurs, the battery is discharged to What is maintained is known (for example, refer to Patent Document 1).

  FIG. 4 is a block diagram showing a configuration of a conventional power conditioner. The power conditioner 50 includes a DC input unit 51, a DC / DC converter 52, a bidirectional inverter 53, an AC input / output unit 54, a DC output unit 55, and a control unit 56 for controlling the whole. In FIG. 4, a direct current (DC) output from a power generation facility 61 such as a solar panel is input to a DC / DC converter 52 via a direct current input unit 51 and converted into a required direct current voltage.

  In the bidirectional inverter 53, DC / AC conversion or AC / DC conversion is controlled by the control unit 56 based on the power generation amount of the power generation facility 61. When the power generation amount of the power generation facility 61 satisfies a predetermined power generation amount, the direct current output of the DC / DC converter 52 is converted into alternating current (AC) by the bidirectional inverter 53 and output to the alternating current input / output unit 54. Is done. As a result, the AC output from the bidirectional inverter 53 is fed to the AC load 62 and reversely flows to the system 65 via the system interconnection switch 64. Further, the DC output of the DC / DC converter 52 is also output to the DC output unit 55. Thereby, the storage battery 63 connected to the DC output unit 55 is charged.

  On the other hand, when the power generation amount of the power generation facility 61 is less than the predetermined power generation amount, alternating current (AC) from the system 65 is fed to the AC load 62 via the system interconnection switch 64 and AC input / output Input to the unit 54. The alternating current input to the alternating current input / output unit 54 is converted into direct current by the bidirectional inverter 53 and output to the direct current output unit 55. Thereby, the storage battery 63 is charged. Therefore, the storage battery 63 is charged using the power generation facility 61 or the system 65 as a charging power source.

  Further, when detecting the occurrence of a system abnormality such as a power failure or a decrease in the system voltage, the control unit 56 turns off the system interconnection switch 64 and disconnects the power generation equipment 61 from the system 65. Then, the control unit 56 controls the AC load 62 to supply AC power using the power generation facility 61 or the storage battery 63 as a power source.

JP 2003-189477 A

  In the power conditioner as shown in FIG. 4, a DC load is connected to the DC output unit 55 instead of the storage battery 63, and the DC output obtained from the power generation facility 61 is boosted by the DC / DC converter 52, It is easily assumed that the load is operated. Moreover, in the configuration of FIG. 4, since the DC output can be obtained from the system 65 by the bidirectional inverter 53, the DC output can be obtained even at night even when the power generation facility 61 is a solar panel, for example. It becomes possible.

  However, in such a configuration, when a DC load is operated by the system 65, the AC of the system 65 is always AC / DC converted by the bidirectional inverter 53. For this reason, depending on the operating DC load, the power conversion efficiency may be a problem. In other words, the DC load can be used only with a DC voltage without pulsating current, and the type in which the use of the pulsating current voltage is prohibited, can be used only with a DC voltage without pulsating current, There are various types, such as a type that does not use pulsating current, and a type that can use both dc voltage and pulsating voltage. Therefore, in the case of a direct current load that can be used even with a pulsating voltage as in the latter two types, power loss due to AC / DC conversion may be a problem.

  Further, when the disconnection occurs, the power source of the DC load is only the power generation facility 61. Therefore, when the output fluctuation of the power generation facility 61 is large, sufficient power may not be supplied to the DC load. For example, in the case where the power generation facility 61 is a solar panel, a DC load cannot be operated because a direct-current output cannot be obtained if a parallel disconnection occurs at night.

  Accordingly, an object of the present invention made in view of such a point is to provide a power conditioner capable of operating a DC load efficiently and stably.

A power conditioner according to the present invention that achieves the above object is as follows.
A bidirectional inverter that selectively executes DC / AC conversion for AC conversion of DC output based on power generation from the power generation facility or AC / DC conversion for DC conversion of AC from a commercial power supply system;
A grid interconnection switch for connecting the bidirectional inverter to the commercial power supply system;
A rectifying unit connected to the commercial power system side of the grid interconnection switch to rectify alternating current from the commercial power system;
A DC output switch for supplying power to a DC load, either a DC output based on power generation from the power generation facility or a DC output of the bidirectional inverter and a rectified output of the rectifying unit;
A storage unit for storing an operation mode for supplying power to the DC load;
A control unit that controls the grid interconnection switch and the DC output switch according to the operation mode stored in the storage unit, and selects whether a DC output or a rectified output is supplied to the DC output switch; It is characterized by comprising.

The storage unit stores a plurality of operation modes,
The operation mode includes a state of selection of an output to supply power to the grid interconnection switch, the DC output switch, and the DC output switch according to a power generation state and a disconnection factor state of the power generation facility,
The control unit is based on an operation mode set according to the DC load from a plurality of operation modes stored in the storage unit, based on a power generation state of the power generation facility and a monitoring result of a disconnection factor. Controlling the selection of the power feed to the grid interconnection switch, the DC output switch, and the DC output switch;
It is characterized by this.

  According to the present invention, it is possible to operate a DC load efficiently and stably.

It is a block diagram which shows the structure of the principal part of the power conditioner which concerns on one embodiment of this invention. It is a figure which shows the example of the operation mode memorize | stored in the memory | storage part of FIG. 1, and the state of each switch. It is a figure which shows the relationship between the operation mode of FIG. 2, and a load type example. It is a block diagram which shows the structure of the conventional power conditioner.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a main part of a power conditioner according to an embodiment of the present invention. The power conditioner 10 includes a DC / DC converter 11, a bidirectional inverter 12, a grid interconnection switch 13, a rectifier unit 14, a selection switch 15, a DC output switch 16, a storage unit 17, and a control unit 18.

  The DC / DC converter 11 inputs direct current (DC) from a power generation facility 21 such as a solar panel, a wind power generator, a fuel cell, or a private power generator, and converts the input voltage into a required direct current voltage. The output of the DC / DC converter 11 is input to the bidirectional inverter 12 and supplied to one selection contact a of the selection switch 15.

  The bidirectional inverter 12 selectively DC / AC converts the DC input from the DC / DC converter 11 under the control of the control unit 18, and reversely flows to the commercial power supply system (system) 22 via the system interconnection switch 13. To do. In addition, the bidirectional inverter 12 selectively AC / DC converts alternating current (AC) input from the system 22 via the system interconnection switch 13 under the control of the control unit 18, and selects the selection contact a of the selection switch 15. To supply.

  The grid interconnection switch 13 is configured by a relay switch that is ON (closed) / OFF (open) controlled by the control unit 18. This grid connection switch 13 is a disconnection factor that must disconnect the grid connection when the voltage of the grid 22 falls below the threshold or when the internal temperature of the power conditioner 10 rises above the threshold. When this occurs, it is turned off. As a result, the power generation facility 21 is disconnected from the system 22.

  The rectification unit 14 rectifies alternating current from the system 22 into direct current, and includes, for example, a half-wave rectification circuit having one diode or a full-wave rectification circuit having a diode bridge. Here, the rectifier 14 is assumed to be a full-wave rectifier circuit. The rectified output of the pulsating flow output from the rectifying unit 14 is supplied to the other selection contact b of the selection switch 15.

  The selection switch 15 is composed of a relay switch having selection contacts a and b. The selection switch 15 is controlled by the control unit 18 to select one of the selection contacts a and b and supplies the selected DC output to the DC output switch 16. The DC output switch 16 includes a relay switch controlled by the control unit 18 and selectively supplies the supplied direct current to the connected direct current load 23.

  The storage unit 17 stores an operation mode for supplying power to the DC load 23. In the present embodiment, a plurality of operation modes are stored in order to cope with various load types (described later) of DC loads connectable to the power conditioner 10. Each operation mode includes the state of the grid connection switch 13, the selection switch 15, and the DC output switch 16 according to the power generation state of the power generation facility 21 and the disconnection factor state.

  For example, the control unit 18 monitors the input of the DC / DC converter 11 indicating the power generation state of the power generation facility 21, and uses the system voltage of the system 22 that is a disconnection factor of the power generation facility 21 or a temperature sensor (not shown). The internal temperature of the conditioner 10 is monitored. And the control part 18 is based on the operation mode set according to the DC load 23 from the several operation modes memorize | stored in the memory | storage part 17 based on the monitoring result of said electric power generation state and a disconnection factor. The grid connection switch 13, the selection switch 15, and the DC output switch 16 are controlled.

  FIG. 2 is a diagram illustrating an example of the operation mode and the state of each switch stored in the storage unit 17. In the present embodiment, assuming that the power generation facility 21 is a solar panel, three modes 1, mode 2, and mode 3 are stored as operation modes. In addition, “abnormality” in FIG. 2 indicates a state of occurrence of a disconnection factor such as when the voltage of the system 22 drops below a threshold or when the internal temperature of the power conditioner 10 rises above a threshold. .

  In Mode 1, if there is no abnormality, both the grid connection switch 13 and the DC output switch 16 are turned ON, and the selection switch 15 is connected to the selection contact a side. Thereby, the DC load 23 has no pulsating flow from the DC / DC converter 11 when the power generation amount exceeds a predetermined value required for the operation of the DC load 23 according to the power generation amount of the power generation facility 21. Direct current is supplied. On the other hand, when the power generation amount of the power generation facility 21 is less than a predetermined value, direct current without pulsating current based on the system power from the bidirectional inverter 12 is supplied. If an abnormality occurs, both the grid connection switch 13 and the DC output switch 16 are turned OFF, and the selection switch 15 remains in the immediately previous state. Thereby, the power supply to the DC load 23 is cut off.

  In mode 2, if there is no abnormality, both the grid connection switch 13 and the DC output switch 16 are turned on, and the selection switch 15 is connected to the selection contact a side. Thus, as described above, the direct current load 23 has a direct current with no pulsating current based on the generated power of the power generation facility 21 from the DC / DC converter 11 or a bidirectional inverter, depending on the power generation amount of the power generation facility 21. The direct current without the pulsating flow based on the grid power from 12 is supplied. If an abnormality occurs, the grid connection switch 13 is turned OFF, the selection switch 15 is set to the selection contact b side, and the DC output switch 16 is turned ON. As a result, the pulsating full-wave rectified output from the rectifying unit 14 is supplied to the DC load 23 at the time of abnormality.

  In mode 3, when there is no abnormality and the power generation amount of the power generation facility 21 exceeds a predetermined value, both the grid connection switch 13 and the DC output switch 16 are turned ON, and the selection switch 15 is connected to the selection contact a side. As a result, the direct current without pulsation based on the generated power of the power generation facility 21 from the DC / DC converter 11 is supplied to the direct current load 23. On the other hand, when an abnormality occurs or when there is no abnormality but the power generation amount of the power generation facility 21 does not satisfy a predetermined value, the grid interconnection switch 13 is turned OFF, the selection switch 15 is on the selection contact b side, and the DC output switch 16 is turned ON. Thereby, in these cases, the pulsating full-wave rectified output from the rectifying unit 14 is supplied to the DC load 23.

  FIG. 3 is a diagram illustrating a relationship between the operation mode of FIG. 2 and an example of a load type. In FIG. 3, three types of type A, type B, and type C are shown as load types of the connected DC load 23. Type A is a DC load that can be used only with a DC voltage without a pulsating current and forbids the use of the pulsating voltage. Type B is a DC load that can be used only with a DC voltage without a pulsating flow, but does not fail even with a pulsating voltage. Type C is a DC load that can be used with either a DC voltage without a pulsating current or a pulsating voltage. FIG. 3 also shows a DC output voltage waveform output from the DC output switch 16.

  As shown in FIG. 3, in mode 2 and mode 3, a type A DC load may be prohibited. Therefore, when using a type A DC load, it is necessary to select mode 1. However, in mode 1, since power is not supplied to the DC load when an abnormality occurs, the DC load cannot be operated, for example, when the temperature of the power conditioner 10 rises and the system is disconnected. . For this reason, if a type A DC load is not used, it is desirable to select mode 2 or mode 3.

  Type C DC loads operate in all states in both mode 2 and mode 3. Therefore, in type C, mode 2 or mode 3 may be used. However, in Mode 3, since the bidirectional inverter 12 is not used when the power generation amount is less than a predetermined value such as at night, the power conversion efficiency is high. Therefore, if only a type C DC load is used, mode 3 is desirable.

  Type B DC load may or may not operate in both mode 2 and mode 3. That is, mode 2 does not operate when an abnormality occurs, and mode 3 does not operate when the amount of power generation is less than a predetermined value in addition to the case where an abnormality occurs. Abnormal conditions do not occur frequently, but when the power generation facility 21 is a solar panel, there is always time during which no power is generated during the day. It is desirable to choose.

  In summary, when even one type A DC load is used, mode 1 is set, and when type B DC load and type C DC load are used together, type B When priority is given to night use, mode 2 is set, and when priority is given to power conversion efficiency, mode 3 is set.

  Here, for example, an operation input unit may be provided in the power conditioner 10 and set by the user from the operation unit, or the power conditioner 10 is connected to a HEMS (Home Energy Management System). May be set by the user via the operation input unit of the HEMS. Also, the control unit 18 receives the load type input by the user, or if the DC load itself has a load type information transmission function at the time of connection, the control unit 18 receives the information and performs control. The operation mode may be automatically set in the unit 18. When only a specific DC load 23 is connected, only the operation mode corresponding to the load type of the DC load 23 may be stored in the storage unit 17.

  As described above, in the present embodiment, the control unit 18 monitors the power generation state and disconnection factor of the power generation facility 21, and corresponds to the DC load 23 stored in the storage unit 17 based on the monitoring result. Since the grid interconnection switch 13, the selection switch 15, and the DC output switch 16 are controlled according to the operation mode to be performed, the DC load 23 can be operated efficiently and stably. In addition, since the rectified output of the rectifying unit 14 may be a pulsating flow output, it can be easily configured.

  In addition, this invention is not limited only to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in FIG. 1, when a required DC voltage is output from the power generation facility 21, the DC / DC converter 11 can be omitted. It is also possible to connect an AC load between the bidirectional inverter 12 and the grid interconnection switch 13 and supply power to the AC load by the power generation equipment 21 or the system 22.

Moreover, although the case where the selection switch 15 is provided has been described in the above embodiment, the control unit 18 performs control so as to select which one of the DC output and the rectified output is the output to be fed to the DC output switch 16. The selection switch 15 can be deleted. Specifically, even if the selection switch 15 is deleted by making the DC voltage generated by the bidirectional inverter 12 higher than the voltage peak from the system 22 (both a and b of the selection switch 15 are connected). Therefore, if the bidirectional inverter 12 is gate-blocked, the input voltage of the DC output switch 16 becomes an output of full-wave rectification, and PWM control is performed. DC voltage output.
When the selection switch 15 is deleted as described above, the control unit 18 does not store the selection contact of the selection switch 15 shown in FIG. What is necessary is just to memorize | store whether it selects as the output which supplies electric power to the switch 16, and to transmit to the control part 18.

DESCRIPTION OF SYMBOLS 10 Power conditioner 11 DC / DC converter 12 Bidirectional inverter 13 System interconnection switch 14 Rectification part 15 Selection switch 16 DC output switch 17 Memory | storage part 18 Control part 21 Power generation equipment 22 Commercial power supply system (system)
23 DC load

Claims (2)

A bidirectional inverter that selectively executes DC / AC conversion for AC conversion of DC output based on power generation from the power generation facility or AC / DC conversion for DC conversion of AC from a commercial power supply system;
A grid interconnection switch for connecting the bidirectional inverter to the commercial power supply system;
A rectifying unit connected to the commercial power system side of the grid interconnection switch to rectify alternating current from the commercial power system;
A DC output switch for supplying power to a DC load, either a DC output based on power generation from the power generation facility or a DC output of the bidirectional inverter and a rectified output of the rectifying unit;
A storage unit for storing an operation mode for supplying power to the DC load;
A control unit that controls the grid interconnection switch and the DC output switch according to the operation mode stored in the storage unit, and that selects whether a DC output or a rectified output is supplied to the DC output switch;
A power conditioner comprising: The storage unit stores a plurality of operation modes,
The operation mode includes a state of selection of an output to supply power to the grid interconnection switch, the DC output switch, and the DC output switch according to a power generation state and a disconnection factor state of the power generation facility,
The control unit is based on an operation mode set according to the DC load from a plurality of operation modes stored in the storage unit, based on a power generation state of the power generation facility and a monitoring result of a disconnection factor. Controlling the selection of the power feed to the grid interconnection switch, the DC output switch, and the DC output switch;
The power conditioner according to claim 1.

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