JP2014130416A - System interconnection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system interconnection device capable of efficiently utilizing power generated by a solar cell module without changing the design of a power conditioner.SOLUTION: A booster circuit unit 13 is provided for each solar cell module 2 in a connection box 11. A system interconnection device is configured in such a manner that: when the amount of solar radiation is large and there is sufficient input power to a power conditioner 12, system interconnection is performed in a state where an output voltage of the booster circuit unit 13 corresponding to the solar cell module 2 whose output voltage is the highest is boosted to the voltage in which a converter circuit unit 16 of the power conditioner 12 stops an operation, and the operation of the converter circuit unit 16 is stopped; and when the input power to the power conditioner 12 is not sufficient, system interconnection is performed by stopping the booster circuit unit 13 corresponding to the solar cell module 2 whose output voltage is the highest, while performing a boosting action both at another booster circuit unit 13 and the converter circuit unit 16.

Description

  The present invention relates to a grid interconnection device, and more particularly to a grid interconnection device that links a plurality of solar cell modules to grid power such as a commercial power source.

  In a solar power generation system in which solar cell modules (solar cell circuits) having different open-circuit voltages are combined, a plurality of solar cells are provided between a power conditioner that links generated power to system power and each solar cell module. A junction box that combines the outputs of the modules is provided, and the junction box is configured to equalize the input voltage to the inverter.

  That is, this type of junction box is provided with a plurality of booster circuits corresponding to the connection of the solar cell modules, and using these booster circuits, the output voltage of the junction box (that is, to the power conditioner) The input voltage is configured to be equal to the voltage of the solar cell module having the highest output voltage (see, for example, Patent Document 1).

FIG. 1 of Japanese Patent No. 4468372 FIG. 1 of JP2003-134667A

  However, such a conventional configuration has the following problems, and improvements have been desired.

  That is, the power conditioner that links the power generated by the solar cell module to the system power includes a converter circuit unit that boosts the DC voltage input from the connection box, and the DC voltage boosted by the converter circuit unit. And an inverter circuit unit for converting into AC power. In the converter circuit unit, AC power (for example, single-phase AC 100V / 200V) to a voltage that can be generated.

  In other words, in this type of photovoltaic power generation system, the boosting operation is performed in each of the junction box and the power conditioner. In the entire system, the boosting function is duplicated in the junction box and the power conditioner. However, depending on the conditions, there is a problem that the efficiency of the entire system deteriorates.

  In this regard, for example, as shown in Patent Document 2, it is conceivable to omit the converter circuit unit of the power conditioner. However, such a configuration is a general configuration of a power conditioner (a converter circuit unit and a converter circuit unit). Therefore, in order to apply to an existing solar cell module, it is necessary to replace the power conditioner, which increases the introduction cost.

  Moreover, in such a configuration, when the amount of solar radiation is small and the generated power in the solar cell module is not sufficient (a sufficient voltage cannot be obtained), the voltage required by the inverter circuit section of the power conditioner is boosted. There was also a problem that the solar cell module could not be connected to the grid power because it could not be generated by the circuit unit.

  The present invention has been made in view of such problems, and the object of the present invention is to efficiently use the power generated by the solar cell module without changing the design of the power conditioner. It is to provide a grid interconnection device.

  In order to achieve the above object, a grid interconnection device according to claim 1 of the present invention links a connection box that combines outputs of a plurality of solar cell circuits into one, and links the output of the connection box to grid power. In the grid interconnection device configured with a power conditioner, the connection box includes a plurality of booster circuit units corresponding to a plurality of solar cell circuits, and a power detection unit that detects power input to the power conditioner. Each of the booster circuit units is provided with control means for controlling the boosting operation in cooperation with other booster circuit units, and the power conditioner is a converter that boosts DC power input from the connection box. A circuit unit, and an inverter circuit unit that converts the output of the converter circuit unit into AC power that can be linked to the system power. The boosting operation is configured to stop when the pressure exceeds a predetermined operation stop voltage, and each of the control means stops the boosting operation of one boosting circuit unit corresponding to the solar cell circuit having the highest output voltage, The other booster circuit unit has the first operation mode in which MPPT control is performed in accordance with the output voltage of the one booster circuit unit, and the output voltage of one booster circuit unit corresponding to the solar cell circuit having the highest output voltage is The boost operation is performed so that the operation stop voltage is exceeded, and the other boost circuit unit has a second operation mode in which MPPT control is performed in accordance with the output voltage of the one boost circuit unit. A control structure for switching between the first operation mode and the second operation mode in accordance with detected power is provided.

  That is, in the grid interconnection device according to claim 1 of the present invention, the booster circuit unit provided in the connection box is configured according to (1) output voltage in accordance with input power (output power of the connection box) to the power conditioner. A first operation mode in which the boosting operation of one boosting circuit unit corresponding to the highest solar cell circuit is stopped, and the other boosting circuit unit performs MPPT control in accordance with the output voltage of the one boosting circuit unit. (2) The step-up operation is performed so that the output voltage of one booster circuit unit corresponding to the solar cell circuit having the highest output voltage is equal to or higher than the operation stop voltage, and the other booster circuit unit is the one booster circuit unit. Therefore, for example, the solar cell circuit has a large amount of solar radiation (the solar cell circuit has a sufficient amount of generated power), so that the MPPT control can be performed in accordance with the output voltage of the solar cell circuit. Obtained When the second operation mode is used, the operation of the converter circuit unit of the power conditioner is stopped to connect to the grid power, while the amount of solar radiation to the solar cell circuit is not large (solar cell circuit If sufficient power generation cannot be obtained with the above-mentioned first operation mode, the boost operation is performed in both the step-up circuit unit of the junction box and the converter circuit unit of the power conditioner by using the first operation mode. It can be performed. In other words, when the amount of solar radiation is large and the generated power in the solar cell circuit is large, it is possible to perform a boosting operation only with the junction box, and the generated power can be efficiently linked to the system power.

  The grid interconnection device according to claim 2 of the present invention is the grid interconnection device according to claim 1, wherein each of the control means is configured such that the power detected by the power detection means is the second operation mode. Even when the power conditioner is implemented, the power conditioner is provided with a control configuration for switching from the first operation mode to the second operation mode when the rated output power is equal to or higher than a power value obtained.

  That is, in the grid interconnection device according to claim 2, the switching from the first operation mode to the second operation mode is performed even when the input power to the power conditioner stops the operation of the converter unit. Since this is performed when the rated output power is obtained, it is possible to prevent the rated output power from being obtained by switching to the second operation mode.

  According to the present invention, the grid interconnection device includes a boost circuit unit and a power conditioner provided in the connection box in accordance with input power from the connection box that combines the outputs of the plurality of solar cell circuits to the power conditioner. It is possible to switch between the first operation mode in which the boosting operation is performed in both of the converter circuit units and the second operation mode in which the boosting operation is performed only with the boosting circuit unit of the junction box. By using the second operation mode when the generated power is obtained, it is possible to perform interconnection with the system power in a state where the operation of the converter circuit unit of the power conditioner is stopped. Therefore, it is possible to efficiently link the power generated when the amount of solar radiation is large and the generated power is large to the grid power.

  Further, according to the present invention, the switching between the first operation mode and the second operation mode is performed by the control means of the booster circuit unit provided in the junction box, and by this switching, the converter circuit unit of the power conditioner Therefore, if the power conditioner has a converter circuit unit that stops operation when the input voltage exceeds a certain value, the present invention is applied without modifying the power conditioner. can do. Therefore, the present invention can be introduced at a low cost.

It is explanatory drawing which shows schematic structure of the solar energy power generation system using the grid connection apparatus which concerns on this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of a photovoltaic power generation system using a grid interconnection device according to the present invention. A grid interconnection apparatus 1 according to the present invention is an apparatus for linking DC power output from a plurality of solar cell modules 2 to grid power 3 such as a commercial power source as shown in FIG. The box 11 and the power conditioner 12 are mainly configured.

  Here, as is well known, the solar cell module 2 connected to the grid interconnection device 1 is configured such that a plurality of solar cells (cells) are connected in series and parallel to obtain necessary DC voltage and DC current. The solar cell module 2 is a module in which a circuit is formed in a panel shape, and the area of the panel, the number of constructions, and the like are appropriately set according to the structure of the installation location (for example, the roof). . For example, in a general dormitory roof, normally, about 3 to 4 circuits (in the illustrated example, 4 circuits 2a to 2d) of solar cell modules 2 are arranged.

  By the way, when a plurality of solar cell modules 2 are used, it is desirable that the open voltage of each solar cell module 2 is uniform, but in actuality, the area varies depending on the relationship with the installation space of the panel (open voltage). The solar cell modules 2 may be used in combination, and the solar power generation system shown in the present embodiment also shows a case where the solar cell modules 2 having different open voltages are combined.

  The connection box 11 is a device for collecting the outputs of the plurality of solar cell modules 2 into one. When solar cell modules 2 having different open-circuit voltages are connected, the connection box 11 is input from the solar cell modules 2a to 2d. The direct current voltages are arranged and input to the power conditioner 12.

  Specifically, the junction box 11 corresponds to the solar cell modules 2 to be connected, and includes at least as many booster circuit units 13 as the solar cell modules 2 to be connected (in the illustrated example, the same number of 4 as the solar cell modules 2). Individual booster circuit portions 13a to 13d) are provided.

  Each booster circuit unit 13 includes a DC-DC converter that boosts a DC voltage input from the corresponding solar cell module 2 to a predetermined voltage. Various sensor means 14 for detecting an input voltage from the battery module 2, an output current and an output voltage from the booster circuit section 13, and a control means 15 for controlling the operation of the booster circuit section 13 are provided.

  The control means 15 is composed of a microcomputer (not shown), and can monitor the output voltage of the other booster circuit section 13 by communication with the microcomputer of the other booster circuit section 13 or by the sensor means 14. The boosting operation of the boosting circuit unit 13 is controlled in cooperation with the other boosting circuit unit 13 based on the output voltage of the other boosting circuit unit 13 (details will be described later). Although not shown, the connection box 11 is also provided with sensors (power detection means) for detecting the output power from the connection box 11, and the control means 15 uses the power detection means to perform power conditioning. The input power to the N 12 is also monitored.

  The power conditioner 12 is a grid-connected inverter device for linking the DC voltage output from the connection box 11 to the grid power 3, and is a converter that boosts the DC voltage output from the connection box 11 to a predetermined voltage. The circuit unit 16 includes an inverter circuit unit 17 for converting the DC voltage boosted by the converter circuit unit 16 into predetermined AC power.

  For example, when the system power 3 is a single-phase AC 200V commercial power supply, the inverter circuit unit 17 is configured by an inverter circuit using the same single-phase AC 200V AC power as the commercial power source as the rated output power, and the converter circuit unit 16 The inverter circuit unit 17 is configured by a DC-DC converter that generates a DC voltage (necessary input voltage of the inverter unit 17) necessary for conversion to AC power of single-phase AC 200V. Note that the DC voltage (required input voltage) required to output the AC power of the single-phase AC 200V in the inverter circuit unit 17 is approximately DC 350V.

  The converter circuit unit 16 is configured to stop its operation when the input voltage from the connection box 11 exceeds the necessary input voltage and reaches a predetermined operation stop voltage Vinmax. That is, when the input voltage from the connection box 11 becomes equal to or higher than the operation stop voltage Vinmax, the converter circuit unit 16 stops the boost operation and supplies the DC voltage input from the connection box 11 to the inverter circuit unit 17 as it is. It has become.

  In FIG. 1, 18 is a grid contact relay contact for linking the power conditioner 12 and the grid power 3, and 19 is generated by the solar cell module 2 when the grid power 3 is blacked out. The relay contact for supplying the electric power to the outlet 20 for independent operation is shown.

Next, the operation of the grid interconnection device 1 configured as described above will be described.
In the grid interconnection device 1, when the power generated by the solar cell module 2 is linked to the grid power 3, the control means 15 of the booster circuit unit 13 provided in the connection box 11 performs the following control. It is configured as follows.

  That is, in this grid interconnection device 1, each control means 15 of the junction box 11 is (1) the solar cell module 2 with the highest output voltage (in the following description, in accordance with the input power to the power conditioner 12). The output voltage of the solar cell module 2a is assumed to be the highest.) The boosting operation of one booster circuit unit 13a corresponding to the above is stopped, and the other booster circuit units 13b to 13d are connected to the one booster circuit unit 13a. A first operation mode in which MPPT control (maximum power point tracking control) is performed in accordance with the output voltage; and (2) the output voltage of one booster circuit unit 13a corresponding to the solar cell module 2a having the highest output voltage is the converter. The boosting operation is performed so that the operation stop voltage Vinmax of the circuit unit 16 is reached, and the other boosting circuit units 13b to 13d are MP in accordance with the output voltage of the one boosting circuit unit 13a. And it is configured to switch the second operation mode performing the T control.

  Specifically, the control means 15 of each booster circuit unit 13 determines the input voltage from the solar cell module 2 from the communication with the microcomputer of the other booster circuit part 13 or the output voltage value detected by the sensor means 14. Is the highest booster circuit unit 13 or not.

  As a result of this determination, if it is determined that the booster circuit unit 13 has the highest input voltage from the solar cell module 2, the control means 15 (control means 15b to 15d in this embodiment) MPPT control is performed in accordance with the output voltage of the booster circuit unit 13 (in this embodiment, the booster circuit unit 13a) having the highest input voltage from the module 2.

  On the other hand, when it is determined that the input voltage from the solar cell module 2 is the highest, the control means 15 (control means 15a in the present embodiment) responds to the input power to the power conditioner 12 detected by the sensor means 14a. When the input power is equal to or higher than the predetermined power value Pa, the boosting operation by the boosting circuit unit 13a is performed so that the voltage input from the solar cell module 2a becomes the operation stop voltage Vinmax of the converter circuit unit 16. Increase the pressure. That is, at this time, the booster circuit unit 13a performs constant voltage control in accordance with the operation stop voltage Vinmax.

  Therefore, in this case, the operation stop voltage Vinmax is input to the converter circuit unit 16 of the power conditioner 12, and the boosting operation of the converter circuit unit 16 is stopped, and the boosting circuit unit 13 of the junction box 11 boosts the voltage. The voltage is supplied to the inverter circuit unit 17 as it is (without being boosted by the converter circuit unit 16). In the inverter circuit unit 17, AC power is generated from the DC power boosted in the connection box 11 in this way, and is connected to the system power 3. At this time, the booster circuit units 13b to 13d other than the booster circuit unit 13a perform MPPT control in accordance with the output voltage of the booster circuit unit 13a as described above.

  Here, for this control, in this embodiment, a configuration is used in which the operation stop voltage Vinmax of the converter circuit unit 16 is stored in advance in the microcomputer of each control means 15. For example, the connection box 11 and the power conditioner 12 are used. The control means 15 can also be configured to acquire the operation stop voltage Vinmax of the converter circuit unit 16 by communication with the power conditioner 12.

  On the other hand, when the input power to the power conditioner 12 is less than the predetermined power value Pa, the control unit 15 (control unit 15a in the present embodiment) stops the boosting operation of the boosting circuit unit 13a. That is, in this case, the voltage input to the booster circuit unit 13a is input to the converter circuit unit 16 of the power conditioner 12 as it is. At this time, the booster circuit units 13b to 13d other than the booster circuit unit 13a perform MPPT control in accordance with the output voltage of the booster circuit unit 13a as described above.

  Therefore, in this case, the voltage input from the solar cell module 2 to the junction box 11 is boosted by both the booster circuit units 13b to 13d and the converter circuit unit 16 of the power conditioner 12, and is supplied to the inverter circuit unit 17. The AC power supplied and converted in the inverter circuit unit 17 is linked to the grid power 3.

  As described above, in the grid interconnection device 1 according to the present invention, the control means 15 of each booster circuit unit 13 provided in the connection box 11 determines (1) the output voltage according to the input power to the power conditioner 12. An operation mode in which the boosting operation of one boosting circuit unit 13 corresponding to the solar cell module 2 having the highest is stopped and the other boosting circuit unit 13 performs MPPT control in accordance with the output voltage of the one boosting circuit unit 13 (First operation mode) and (2) boost operation is performed so that the output voltage of one boost circuit unit 13 corresponding to the solar cell circuit having the highest output voltage becomes the operation stop voltage Vinmax of the converter circuit unit 16 The other booster circuit unit switches between the operation mode (second operation mode) in which MPPT control is performed in accordance with the output voltage of the one booster circuit unit 13. When the solar cell module 2 has a large amount of solar radiation and sufficient generated power can be obtained (in other words, the boosting operation by the converter circuit unit 16 of the power conditioner 12 is stopped and the boosting is performed only by the connection box 11. When the rated output power can be output from the inverter circuit unit 17 even when the operation is performed), when the predetermined solar power Pa is set so as to operate in the second operation mode, there is a sufficient amount of solar radiation. The converter circuit unit 16 of the power conditioner 12 is stopped, and the boosting operation is performed only by the connection box 11.

  Here, the predetermined power value Pa, which is a reference for switching between the first operation mode and the second operation mode, is the boost circuit unit 13 provided in the connection box 11 or the converter circuit unit 16 of the power conditioner 12 and Although it is set as appropriate based on the specifications of the inverter circuit unit 17, the rated output power of the power conditioner 12 can be obtained from the inverter circuit unit 17 even when operated in the second operation mode. It is set to be equal to or greater than the power value.

  Thus, in the grid interconnection device 1 according to the present invention, the booster circuit unit 13 and the power conditioner 12 provided in the connection box 11 are provided according to the input power from the connection box 11 to the power conditioner 12. Since the first operation mode in which the boosting operation is performed in both of the converter circuit sections 16 and the second operation mode in which the boosting operation is performed only by the boosting circuit section 13 of the junction box 11 are switched, a solar cell circuit is sufficient. By using the second operation mode when the generated power is obtained, the power generated when the amount of solar radiation is large and the generated power is large can be efficiently linked to the system power 3.

  Further, in the grid interconnection device 1 according to the present invention, switching between the first operation mode and the second operation mode is performed by the control means of the booster circuit unit 13 provided in the connection box 11, and by this switching, Since the operation / stop of the converter circuit section 16 of the power conditioner 12 is controlled, the present invention can be applied without replacement of an existing power conditioner, and the apparatus according to the present invention is introduced at low cost. be able to.

  The above-described embodiments show preferred embodiments of the present invention, and the present invention is not limited to these, and various design changes can be made within the scope of the invention.

  For example, in the above-described embodiment, when the control means 15 of the booster circuit unit 13 to which the highest voltage is input from the solar cell module 2 determines that the input power to the power conditioner 12 is equal to or higher than a predetermined power value Pa. In the above example, the output voltage of the booster circuit unit 13 is boosted so as to be equal to the operation stop voltage Vinmax of the converter circuit unit 16. It is also possible to use a voltage value other than the operation stop voltage Vinmax.

  In the above-described embodiment, the connection box 11 is provided with four booster circuit units 13. However, a plurality of booster circuit units 13 are provided according to the number of solar cell modules 2 connected to the connection box 11. For example, a configuration including three circuits or four circuits or more as well as two circuits may be adopted.

1 Grid interconnection device 2 Solar cell module (solar cell circuit)
3 System power 11 Connection box 12 Power conditioner 13 Booster circuit unit 14 Sensor unit 15 Control unit 16 Converter circuit unit 17 Inverter circuit unit

Claims (2)

In a grid interconnection device composed of a connection box that combines outputs of a plurality of solar cell circuits into one, and a power conditioner that links the output of the connection box to grid power,
The junction box includes a plurality of booster circuit units corresponding to a plurality of solar cell circuits, and power detection means for detecting power input to the power conditioner, and each booster circuit unit includes another booster. A control means for controlling the boosting operation in cooperation with the circuit unit is provided,
The power conditioner includes a converter circuit unit that boosts DC power input from the connection box, and an inverter circuit unit that converts the output of the converter circuit unit into AC power that can be linked to the system power. The converter circuit unit is configured to stop the boost operation when the input voltage is equal to or higher than a predetermined operation stop voltage.
Each of the control means stops the boosting operation of one booster circuit unit corresponding to the solar cell circuit having the highest output voltage, and the other booster circuit unit performs MPPT control according to the output voltage of the one booster circuit unit. A first operation mode in which the output voltage of one booster circuit unit corresponding to the solar cell circuit having the highest output voltage is boosted so that the output voltage is equal to or higher than the operation stop voltage, and the other booster circuit units are A second operation mode in which MPPT control is performed in accordance with an output voltage of one booster circuit unit, and the first operation mode and the second operation mode according to the power detected by the power detection means A grid interconnection device comprising a control configuration for switching between the two.   Each of the control means is configured such that when the power detected by the power detection means is equal to or higher than a power value at which a rated output power can be obtained by the power conditioner even when the second operation mode is performed. The grid interconnection apparatus according to claim 1, further comprising a control configuration for switching from an operation mode to the second operation mode.

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