JP3208284B2 - Solar power generation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic power generation system for connecting a solar cell to a commercial power system via an inverter, and more particularly, to stopping the operation of the commercial power system due to an accident. The present invention relates to a photovoltaic power generation system capable of self-sustained operation of supplying generated power of a photovoltaic cell only to a domestic load.

[0002]

2. Description of the Related Art In recent years, a solar cell power generation system in which a solar cell is installed in each home, factory, or area and connected to a commercial power system of a power company, and surplus power of the solar cell flows backward to the commercial power system has been developed. Has been put to practical use.

In a solar cell power generation system, a solar cell is connected to a commercial power system via an inverter, and a domestic load is connected to an output terminal of the inverter. Thereby, the output of the solar cell is converted from DC to AC, and the AC power is supplied to the commercial power system and the domestic load.

In a conventional solar cell power generation system, when a power failure occurs in a commercial power system due to a disaster or lightning strike, the operation of the inverter is stopped. In order to supply and effectively use the power generated by the solar cell, the operation of the inverter to operate independently and supply the power from the solar cell to the home load while the interconnection to the commercial power system is disconnected has been studied. I have.

[0005] In addition, in order to cover the required power at night when a power failure occurs, a power storage means including a charger and a storage battery is interposed between the solar cell and the inverter. Supply to the load,
A method of charging the storage battery with the surplus power, discharging the storage battery at night, and supplying the power to a load is being studied.

[0006]

However, in a conventional solar cell power generation system having a storage battery, a charger is interposed between the solar cell and the inverter. Power generation efficiency was low.

In a solar cell power generation system, control for tracking the maximum power point is performed. In a configuration in which a storage battery is connected to the output terminal of the solar cell, the output voltage of the solar cell is regulated by the output voltage of the storage battery. There was a problem that operation at the maximum power point was hindered. In particular, when the voltage of the storage battery is reduced by discharging, the voltage greatly deviates from the maximum power point.

[0008] Further, in a state where a power failure occurs in a commercial power system due to a disaster, there is a possibility that the domestic wiring may be damaged. The same voltage as in the interconnection operation, for example, 200 V, is output, and the storage battery is charged by this high voltage, which is dangerous especially when the coating on the home wiring is peeled off.

[0009] It is an object of the present invention to improve the power generation efficiency of the entire system and enable operation at the maximum power point in a solar cell power generation system provided with power storage means. Another object of the present invention is to make it possible to charge the power storage means with a sufficiently low voltage in a solar cell power generation system provided with the power storage means, and to achieve safety in the self-sustaining operation mode.

[0010]

The solar cell power generation system according to the present invention is capable of simultaneously supplying the output of a solar cell (1) to a load (4) and a commercial power system (3) via an inverter (2). A grid connection operation mode, and a night mode in which the inverter (2) is stopped to supply power of the commercial power system (3) to the load (4);
Switching operation can be performed between three modes of an independent operation mode in which the output of the solar cell (1) is supplied to the load (4) while the inverter (2) is disconnected from the commercial power system (3).

Here, the characteristic structure of the solar cell power generation system of the present invention is that a charge and discharge connected between the solar cell (1) and the commercial power system (3) in parallel with the inverter (2). Power storage means capable of performing the above operation, disconnecting the parallel connection of the power storage means in the interconnected operation mode, supplying power from the commercial power system (3) to the power storage means in the night mode, and providing the power storage means in the independent operation mode. That is, disconnection / connection means for supplying the output of the storage means to the inverter (2) is provided. The disconnecting / connecting means includes, for example, a solar cell (1), an inverter (2), a commercial power system (3), and a load.
(4) The relay can be easily configured by interposing relays that can be opened and closed at the connection points of the power storage means and by controlling these relays according to the mode.

In another solar cell power generation system according to the present invention, the solar cell (11) is configured by arranging a plurality of modules (12). In the characteristic configuration, a power storage means is connected between the solar cell (11) and the commercial power system (3) in parallel with the inverter (2), and the power storage means is connected to the solar cell ( Charging and discharging can be performed at a voltage corresponding to the output voltage of one module (12) of (11).
In addition, it comprises disconnection / connection means and voltage conversion means, and the disconnection / connection means connects a plurality of modules (12) of the solar cell (11) in series with each other in the interconnection operation mode,
Disconnects the parallel connection of the power storage means, supplies power from the commercial power system (3) to the power storage means in the night mode, and a plurality of modules (12) of the solar cell (11) in the independent operation mode.
Are connected in parallel with each other, and the output of the power storage means is supplied to the inverter (2). The voltage conversion means reduces the voltage to the input voltage of the power storage means when supplying power from the commercial power system (3) to the power storage means in the night mode, and in the independent operation mode,
It boosts the output voltage of the inverter (2) to the system voltage. The disconnecting / connecting means can likewise be easily constituted by a plurality of relays whose opening and closing can be controlled.

[0013]

In the solar cell power generation system according to the present invention, in the interconnection operation mode, the power storage means is disconnected, and the output of the solar cell (1) is converted into AC through the inverter (2), and then the load is changed. (4) and the commercial power system (3). Here, the power storage means does not intervene in the power supply path from the solar cell (1), and thus no loss occurs due to the operation of the power storage means. Also, the output voltage of the solar cell (1) is not affected by the voltage of the power storage means, and therefore, operation at the maximum power point is possible.

In the night mode in which the inverter (2) is stopped, the power line from the commercial power system (3) to the power storage means is connected to supply power from the commercial power system (3) to the power storage means. And charge it. In addition, electric power from the commercial power system (3) is supplied to the load (4) to cover the necessary power at night.

Further, in the self-sustained operation mode, the output of the solar cell (1) is inputted to the inverter (2), and the electric power from the electric power storage means charged at night is inputted to the inverter (2). Thus, the AC power output from the inverter (2) is supplied to the load (4). When the power demand of the load (4) is low, the surplus power of the solar cell (1) is supplied to the power storage means, and the power storage means is charged.

In another solar cell power generation system according to the present invention, in the interconnected operation mode, a plurality of modules (12) constituting the solar cell (11) are connected in series with each other, and the high efficiency of the inverter (2) is improved. A sufficiently high voltage required for operation is input to the inverter (2). Here, solar cell (1)
Since no power storage means is interposed in the power supply path from, there is no loss associated with the operation of the power storage means, and operation at the maximum power point is possible.

In the night mode, electric power from the commercial electric power system (3) is supplied to the electric power storage means and charged. At this time, the power obtained from the commercial power system (3)
(100 V) is reduced to the input voltage (for example, 24 V) of the power storage means and is input to the power storage means. In addition, electric power from the commercial power system (3) is supplied to the load (4) to cover the necessary power at night.

In the self-sustaining operation mode, a plurality of modules (12) constituting a solar cell (11) are connected in parallel with each other,
The low voltage corresponding to the voltage of the power storage means
Input to (2). Also, low-voltage power from the power storage means charged at night is input to the inverter (2). As a result, the AC power obtained from the inverter (2) is boosted to the system voltage by the
It is supplied to (4). The surplus power of the solar cell (11) is charged to the power storage means.

[0019]

According to the photovoltaic power generation system of the present invention, the power loss in the interconnection operation mode is suppressed.
The power generation efficiency of the entire system is improved, and operation at the maximum power point becomes possible. Further, according to another solar cell power generation system according to the present invention, in the interconnected operation mode, a high voltage is supplied to the inverter, so that the operation efficiency of the inverter is high. Of course, in the self-sustaining operation mode, the power storage means is charged with a sufficiently low voltage corresponding to the output voltage of one module (12) of the solar cell (11). Safe even if damaged.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of the present invention will be described below in detail with reference to the drawings. First Embodiment As shown in FIG. 1, a solar cell capable of outputting 200 V DC
(1) is connected to a commercial power system (3) via an inverter (2), and a load (4) is connected to an output terminal of the inverter (2). Transformer (7) is interposed between 3).

A charger (5) is connected in parallel to the inverter (2) and the load (4).
A 200 V storage battery (6) is connected. The charger (5)
Can charge the storage battery (6) by receiving 200V DC output from the solar battery (1), and
The storage battery (6) can be charged by receiving AC100V power supplied from (3) via the transformer (7).

Further, a first relay RY1 (81), a primary winding of a transformer (7) and a charger are connected between the inverter (2) and the load (4).
The second relay RY2 (82) between the (5), the third relay RY3 (83) and the transformer (7) between the solar cell (1) and the charger (5).
A fourth relay RY4 (84) between the next winding and the commercial power system (3)
The opening and closing of these relays are controlled by a control circuit (not shown).

FIG. 2 shows the operation of the solar cell power generation system. First, in step S1, the commercial power system
It is determined whether the voltage of (3) exceeds 80 V, and Y
In the case of ES, the process proceeds to step S2, and further the solar cell
It is determined whether or not the output voltage of (1) exceeds 140V. The voltages of the solar cell (1) and the commercial power system (3) can be detected by a well-known voltage detecting means such as PT.

When YES is determined in the step S2, the second relay RY2 (82) and the third relay RY3 (83) are turned off in a step S3, and the first relay RY1 (81) in a step S4. ) And the fourth relay RY4 (84)
After setting N, the process proceeds to the interconnection operation mode in step S5.

In the interconnection operation mode, after the DC output of the solar cell (1) is converted to AC by the inverter (2), the first
While being supplied to the load (4) via the relay RY1 (81),
Further, through the transformer (7) and the fourth relay RY4 (84),
It is supplied to the commercial power system (3). Where the inverter
In (2), the well-known maximum power point tracking control is performed, and the apparatus always operates at the maximum power point.

If NO is determined in step S2, the first relay RY1 (81) and the third relay RY3 (83) are turned off in step S6, and the second relay RY2 (82) is turned on in step S7. ) And the fourth relay RY4 (84)
After setting N, in step S8 the charging mode (night mode)
Move to

In the charging mode, electric power is supplied from the commercial power system (3) to the load (4) through the fourth relay RY4 (84) and the transformer (7), and from the primary winding of the transformer (7). The obtained AC power of 100 V is supplied to the charger (5) via the second relay RY2 (82). As a result, the storage battery (6) is charged at low cost by the nighttime power.

If NO is determined in the step S1, the second relay RY2 (82) and the fourth relay RY4 (84) are turned off in a step S9, and a step S10 is executed.
After turning on the first relay RY1 (81) and the third relay RY3 (83) in step S11, the operation shifts to the independent operation mode in step S11.

In the self-sustaining operation mode, the DC output of the solar cell (1) is supplied to the inverter (2) and the storage battery (6)
Is supplied to the inverter (2) via the third relay RY3 (83). As a result, AC 100 V obtained from the inverter (2) is supplied to the load (4) via the first relay RY1 (81). When the power consumption of the load (4) is lower than the power generated by the solar cell (1), the surplus power of the solar cell (1) is input to the charger (5) through the third relay RY3 (83), The storage battery (6) is charged. In the independent operation mode, the second relay RY2 (82) is turned on and the inverter
The output power from (2) is supplied to the charger (5), and the storage battery (6)
A method of charging is also possible.

In the above-mentioned solar cell power generation system, when the commercial power system (3) is out of power, that is, in the self-sustaining operation mode, both the solar cell (1) and the storage battery (6) cover the required power of the load (4). As a result, energy can be effectively used.

Second Embodiment As shown in FIG. 3, a solar cell (11) is constituted by arranging a plurality of (9) modules (12), and one module (12) is
Output of C24V is possible. The solar cell (11) is connected to a commercial power system (3) via an inverter (2),
A load (4) is connected to the output terminal of the inverter (2), and a transformer (71) is interposed between the connection point and the commercial power system (3).

A charger (51) is connected in parallel to the inverter (2) and the load (4).
A 24 V storage battery (61) is connected. The charger (51)
Can charge the storage battery (61) by receiving 24V DC output from the solar battery (11),
The storage battery (61) can be charged by receiving 24V AC power obtained from the next auxiliary winding (74).

Further, a first voltage is applied between the inverter (2) and the load (4).
Relay RY1 (91), second relay RY2 (92) between primary auxiliary winding (74) of transformer (71) and charger (51), solar cell (11)
The third relay RY3 (93) and the transformer (7)
A fourth relay RY4 (94) is interposed between the secondary winding (73) of 1) and the commercial power system (3). Furthermore, the solar cell (11) has
Fifth relay RY5 (95) and sixth relay R of contact switching type
Y6 (96) is connected so that nine modules (12) can be connected to each other in series or in parallel. Furthermore, the output terminal of the inverter (2) and the transformer (71)
Between the first auxiliary winding (74) and the seventh relay RY7 (97).
Is interposed. Opening / closing or switching of these relays is controlled by a control circuit (not shown).

FIG. 4 shows the operation of the solar cell power generation system. First, in step S21, it is determined whether the voltage of the commercial power system (3) exceeds 80V,
In the case of YES, the process proceeds to step S22, in which the fifth relay RY5 (95) and the sixth relay RY6 (96) are switched to the a contact, and in step S23, the output voltage of the solar cell (11) exceeds 140V. Determine if it is.

If YES is determined in the step S23, the second relay RY2 (92) and the third relay RY2 (92) are determined in a step S24.
The relay RY3 (93) and the seventh relay RY7 (97) are turned off, and the first relay RY1 (91) is set in step S25.
And after turning on the fourth relay RY4 (94), step S
At 26, the mode shifts to the interconnection operation mode.

In the interconnected operation mode, the modules (12) of the solar cell (11) are connected in series with each other, and
216V DC output obtained from the first relay RY1 (9) is converted to 100V AC through the inverter (2).
1) to the load (4), and further to the transformer (7
1) and through the fourth relay RY4 (94), the commercial power system (3)
Supplied to Here, the inverter (2) is always operated at the maximum power point by performing the well-known maximum power point tracking control.

If NO is determined in the step S23, the first relay RY1 (91), the third relay RY3 (93), and the seventh relay RY7 (97) are turned off in a step S27, and in a step S28. After turning on the second relay RY2 (92) and the fourth relay RY4 (94) in step S2,
At 9, the mode shifts to the charging mode (night mode).

In the charging mode, the commercial power system (3) passes through the fourth relay RY4 (94), the secondary winding (73) of the transformer (71) and the primary main winding (72) to the load (4). The power is supplied and the AC obtained from the primary auxiliary winding (74) of the transformer (71) is supplied.
The 24V power is supplied to the charger (51) via the second relay RY2 (92).
Supplied to As a result, the storage battery (61) is charged at low cost by nighttime power.

If NO is determined in the step S21, the fifth relay RY5 (95) and the sixth relay RY5 (95) are determined in a step S30.
By switching the relay RY6 (96) to the contact b, the solar cell (11)
Are connected in parallel with each other. Then, in step S31, the first relay RY1 (91), the second relay RY2 (92), and the fourth relay RY4 (94) are turned off, and in step S32, the third relay RY3 (93) and the seventh relay RY3 (93) are turned off. After turning on RY7 (97), step S3
At 3, the mode shifts to the independent operation mode.

In the self-sustaining operation mode, a 24 V DC output obtained from the solar cell (11) is supplied to the inverter (2), and a 24 V DC power from the storage battery (61) is supplied to the third relay RY3 (93). After that, it is supplied to the inverter (2). As a result, AC24V obtained from inverter (2)
Via the relay RY7 (97), the primary auxiliary winding (7) of the transformer (71)
4), whereby the primary main winding of the transformer (71)
100V AC obtained from (72) is supplied to the load (4). When the power consumption of the load (4) is lower than the power generated by the solar cell (11), the surplus power of the solar cell (11) is input to the charger (51) via the third relay RY3 (93), The storage battery (61) is charged.

According to the above solar cell power generation system, the solar cell (11) and the storage battery (61) are used at 24 V in the independent operation mode. Safer than when used at 200V. Also, even if some modules (12) of the solar cell (11) are damaged and cannot generate power, since the plurality of modules (12) are connected in parallel, other normal modules (12) Can generate electricity.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a solar cell power generation system according to a first embodiment.

FIG. 2 is a flowchart showing an operation of the solar cell power generation system.

FIG. 3 is a block diagram illustrating a configuration of a solar cell power generation system according to a second embodiment.

FIG. 4 is a flowchart showing the operation of the solar cell power generation system.

[Explanation of symbols]

 (1) Solar cell (2) Inverter (3) Commercial power system (4) Load (5) Charger (6) Storage battery (81) First relay RY1 (82) Second relay RY2 (83) Third relay RY3 ( 84) Fourth relay RY4

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02J 1/00 304 H02J 3/38 H02J 7/35

Claims (2)

(57) [Claims] 1. A solar cell (1) is connected to a commercial power system (3) via an inverter (2), and the inverter (2)
A load (4) is connected between the power supply (3) and the commercial power system (3), and is capable of simultaneously supplying the output of the solar cell (1) to the load (4) and the commercial power system (3) via the inverter (2). System operation mode,
A night mode in which the inverter (2) is stopped and power from the commercial power system (3) is supplied to the load (4);
Is disconnected from the commercial power system (3) and the solar cell (1)
In a solar cell power generation system capable of switching operation between three modes of a self-sustained operation mode for supplying the output of the solar cell to a load (4), an inverter is provided between the solar cell (1) and the commercial power system (3).
The power storage means capable of charging and discharging connected in parallel to (2) and the parallel connection of the power storage means in the interconnected operation mode are disconnected, and the power from the commercial power system (3) is used in the night mode. A photovoltaic power generation system, comprising: disconnection / connection means for supplying power to the storage means and supplying the output of the power storage means to the inverter (2) in the independent operation mode. 2. A solar cell (11) is connected to a commercial power system (3) via an inverter (2), and the solar cell (11) is connected to the inverter (2).
A load (4) is connected between the power supply (3) and the commercial power system (3), and is capable of simultaneously supplying the output of the solar cell (11) to the load (4) and the commercial power system (3) via the inverter (2). System operation mode,
A night mode in which the inverter (2) is stopped and power from the commercial power system (3) is supplied to the load (4);
Is disconnected from the commercial power system (3) and the solar cell (11)
In a solar cell power generation system capable of switching operation between three modes of a self-sustaining operation mode for supplying an output of the solar cell to a load (4), a solar cell (11) is configured by arranging a plurality of modules (12); Inverter between battery (11) and commercial power system (3)
Power storage means connected in parallel to (2) and capable of charging and discharging at a voltage corresponding to the output voltage of one module (12) of the solar cell (11); Multiple modules of (11) (1
2) are connected in series with each other, and the parallel connection of the power storage means is disconnected. In the night mode, power from the commercial power system (3) is supplied to the power storage means. And a disconnecting / connecting means for supplying the output of the power storage means to the inverter (2), and power supply from the commercial power system (3) in the night mode. And a voltage conversion means for stepping down the voltage to the input voltage of the power storage means when supplying the voltage to the storage means and boosting the output voltage of the inverter (2) to the system voltage in the independent operation mode. Solar cell power generation system.