JP2013207970A - Power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion system that enables an owner of the power conversion system and a user of a consumer to use electric power from a solar battery even when the owner of the power conversion system and the user of the consumer are different from each other.SOLUTION: An electric power generated at a generator 10 is distributed into a plurality of outputs by using first inverter circuits 42a-42d and a second inverter circuit 42e. The outputs of the first inverter circuits 42a-42d are supplied for self consumption in consumers 2a-2d, while the output of the second inverter circuit 42e is inversely flowed into a commercial power system G.

Description

The present invention relates to a power conversion system that converts power generated by a generator into AC power, and distributes and supplies this AC power to indoor wiring of a plurality of consumers.

Conventionally, a power conversion system that distributes generated power of a common generator (for example, a solar cell, a fuel cell, a wind power generator, etc.) to a plurality of consumers at a predetermined distribution ratio has been proposed (Patent Document 1). .

JP 2003-134673 A

Such a power conversion system is, for example, a distribution that is determined in advance according to the investment ratio or the like when it is desired to provide a common generator in an apartment house, or when a plurality of neighboring customers want to provide a common generator. The generator was used using the ratio.

This power conversion system includes a solar cell as a generator, and directly supplies the power generated by the solar cell to the power conversion device of each consumer. The generated power is generated by operating each power conversion device so that each consumer can take in a power having a predetermined distribution ratio.

However, if the generated power of all the solar cells is distributed to each consumer as in the conventional power conversion system, if the owner of the power conversion system and the person using the consumer are different, for example, each demand If the owner of the house is the owner of the power conversion system and a resident who has leased with the owner of the consumer (the person who uses the consumer) lives in the consumer, the owner of the power conversion system The person cannot use the generated power unless the customer is used.

This invention is an invention made in view of the above-mentioned problem, and even if the owner of the power conversion system and the user of the customer are different, the owner of the power conversion system and the customer use the generated power of the solar cell. It is an object of the present invention to provide a power conversion system in which a person who uses can use the power generated by a solar cell.

In order to achieve the above object, the power generated by the generator is distributed to a plurality of outputs using the first inverter circuit and the second inverter circuit, and the output of the first inverter circuit is self-contained within the consumer. The power is supplied for consumption, and the output of the second inverter circuit is caused to flow backward to the commercial power system.

According to the present invention, even if the owner of the power conversion system and the user of the customer are different, the power is supplied to the customer by the first inverter circuit. By using the second inverter circuit to flow backward to the commercial power system, the owner of the power conversion system can use the power generated by the solar cell in the form of selling power to the commercial power system. it can.

Further, in the above-described invention, the first inverter according to the conversion of the unit price obtained by the control circuit in the control circuit configured to be able to obtain information on the unit price of the power sold to flow backward to the commercial power system The ratio of the power distributed to the circuit and the second inverter circuit is changed.

In the above-mentioned invention, when the power supplied from the first inverter circuit is larger than the self-consumed power in the consumer, the power supply to the consumer is reduced and the power supplied from the second inverter circuit is reduced. It is characterized by increasing.

In the above-described invention, it is preferable that the second inverter circuit has a larger output power than the first inverter circuit.

According to the present invention, even if the owner of the power conversion system and the user of the consumer are different, the owner of the power conversion system and the person using the consumer use the generated power of the solar battery. A power conversion system capable of being supplied can be provided.

It is a schematic diagram which shows the Example of the installation state of a power conversion system. It is a figure which shows the electric power selling fee for every time slot | zone.

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an installation state of the power conversion system 1. As shown in this figure, each consumer 2a-
2d is supplied with AC power, and a common power conversion system 1 is provided to the consumers 2a to 2d.

The power conversion system 1 includes a solar cell 10 (generator) common to the consumers 2a to 2d,
The power converter 11 is provided. In the present embodiment, the consumers 2a to 2d constitute one apartment house (for example, an apartment or an apartment). The solar cell 10 is installed on the rooftop of this building, for example, and the power converter 11 is arrange | positioned beside this building. The generated power of the solar cell 10 is input to the power conversion device 11, and the power conversion device 11 uses the generated power to supply power to the indoor wirings 31a and 2b of the respective consumers 2a to 2d and the customer 2a. It distributes and supplies to the system G. In addition, the consumers 2a-2d may be comprised not only in an apartment house but in the neighboring detached house.

Each consumer 2a-2d is AC power supplied by the commercial power grid G and AC power supplied by the power converter 11 (AC power converted by inverter circuits 42a-42d described later).
And the AC power is superimposed and supplied to the loads in the consumers 2a to 2d.

Next, the power converter 11 will be described. The power converter 11 includes a booster circuit 41, a plurality of first inverter circuits 42a to 42d, a second inverter circuit 42e, grid interconnection relays 43a to 43d (switches), and a control circuit 44. Further, the booster circuit 41, the plurality of first inverter circuits 42a to 42d, the second inverter circuit 42e, the grid interconnection relays 43a to 43d, and the control circuit 44 are housed in a common housing, and this housing is arranged. It is put together in a common place.

The booster circuit 41 is connected between the solar cell 10 and the plurality of first inverter circuits 42 a to 42 d and boosts the voltage of the solar cell 10. The booster circuit 41 can be a reactor, IGBT or F
It consists of a switch element such as ET, a diode circuit, and a capacitor. Specifically, the reactor and the diode are connected in series to form a series circuit, and the reactor side of the series circuit is connected to the positive electrode side of the solar cell 10. Moreover, the connection point of a reactor and a diode and the negative electrode side of a solar cell are connected via the switch element. Moreover, the diode side of the series circuit and the negative electrode side of the solar cell are connected via a capacitor. The booster circuit 41 periodically conducts / cuts off the switch element. For example, the ratio of conducting the switch element every cycle (hereinafter referred to as O).
By setting the N ratio, the voltage of the solar cell is boosted at a desired boost ratio and output to both ends of the capacitor.

The power converter 11 converts the power generated by the solar cell 1 into the first inverter circuits 42a to 42a-4.
2d and the second inverter circuit 42e are used to distribute to a plurality of outputs.
The plurality of first inverter circuits 42 a to 42 d each convert the generated power of the common solar cell 10 input via the booster circuit 41 into AC power. First inverter circuit 42a
To 42d are connected to consumers 2a to 2d that receive supply of power from the commercial power grid G, respectively.
The outputs of the first inverter circuits 42a to 42d are respectively distributed for self-consumption within the consumers 2a to 2d.
The second inverter circuit 42e is connected to the commercial power system G and causes the output of the second inverter circuit to flow backward to the commercial power system G. In addition, the first inverter circuit 42a to 42d uses the second inverter circuit 42e having a larger power that can be output. For example, the first inverter circuit that outputs 2.7 kW is used, and the second inverter circuit is 1
Use one that outputs 0 kW.

Since the first inverter circuits 42a to 42d are respectively housed in the housing, the first inverter circuits 42a to 42d are supplied from the housing to the indoor wirings 31a and 31b and the commercial power system G through the AC wiring. Thereby, the plurality of first inverter circuits 42a to 42d supply the generated power of the common solar cell 10 to the indoor wirings 31a and 31b of the plurality of consumers 2a to 2d and the consumer 2a. Distribute to G respectively.

Each of the inverter circuits 42a to 42e has a bridge circuit including four switch elements such as IGBT and FET, and a filter circuit including two reactors and a capacitor. In the bridge circuits of the inverter circuits 42a to 42e, the DC side is connected to both ends of the capacitor of the booster circuit, and the AC side is connected to the filter circuit. The filter circuit is 2
One end of each of the reactors is connected to a capacitor, and the other end of each reactor is connected to the AC side of the bridge circuit. The inverter circuits 42a to 42e have a predetermined PWM (Pulse
Using the Width Modulation signal, the four switch elements are turned on / off to generate AC power having a waveform synchronized with the commercial power system at both ends of the capacitor of the filter circuit, and the indoor wiring 31a of the consumers 2a to 2d. , 31d and the commercial power system G.

The grid interconnection relays 43a to 43e are respectively provided on the output side of the inverter circuits 42a to 42e (between the first inverter circuits 43a to 43d and the consumers 2a to 2d and the second inverter circuit and commercial power). The first inverter circuits 42a to 42a-4)
2d and the consumers 2a to 2d, and the second inverter circuit 42e and the commercial power system G are short-circuited / opened. As a result, the grid interconnection relays 43a to 43b cut off the AC power output from the first inverter circuits 42a to 42d to the consumers 2a to 2d and from the second inverter circuit 42e to the commercial power grid G. Can do.

The control circuit 44 is composed of, for example, a microcomputer, and operates the booster circuit 41 and the inverter circuit 4.
The operation of 2a to 42e and the operation of the grid interconnection relays 43a to 43e are controlled.

The control circuit 44 controls the ON ratio of the booster circuit 41 so that the generated power of the solar cell 10 (input power to the booster circuit 41) is maximized. Specifically, the generated power of the solar cell 10 input to the booster circuit 41 is calculated from the input current and the input voltage obtained from the input current sensor 51 and the input voltage sensor 52. If the calculated generated power is greater than the previously calculated generated power, change the ON ratio to the same one that changed the previous ON ratio (lower the previous ON ratio, lower it again, and increase the previous ON ratio) If you do, increase it). Conversely, if the generated power is smaller than the previously calculated power, change the ON ratio to the opposite of the previous ON ratio change (the higher the previous ON ratio, the higher the previous ON ratio) If so, lower).

The control circuit 44 generates a PWM signal for conducting / cutting off the switch elements of the inverter circuits 42a to 42e. Specifically, when the voltage of the commercial power grid G supplied to each consumer is assumed to be the same, the explanation will be made easy, and the control circuit 44 will have the inverter circuits 42a to 42.
e output current command values Ita to Ite are calculated, and the inverter circuits 42a to 4e so that the output currents Ia to Ie of the inverter circuits 42a to 42e coincide with the output current command values Ita to Ite.
A PWM signal that outputs the output voltage 2e is generated. Output current command value Ita at this time
The ratio of ~ It is set to be the same as the ratio of power distributed to the inverter circuits 42a to 42e. In consideration of the AC voltage on the consumer side, the power output from the inverter circuit may be controlled according to the distribution ratio.

When the ratio (distribution ratio) of the electric power Pa to Pe that distributes the generated electric power Pi of the solar cell 10 to each of the consumers 2a to 2d and the commercial electric power system G is represented by ra to re, the inverter circuits 42a to 42a.
The output current command values Ita to Ite of 2e can be calculated as follows.

First, the relationship between the distributed power Pa to Pe, the distribution ratio ra to re, and the input power is P
n = rn × Pi (n = a, b, c, d, e). And the distributed power is Pn =
Since In × Vn (n = a, b, c, d, e), the current values (output current command values) Ita to Ite to be output to the inverter circuits 42a to 42e are Ia to Ie at this time. In summary, the output current command value is Itn = rn × Pi / Vn (n = a, b, d). still,
Although the values Va to Ve detected by the output voltage sensor can be used for Vn, since the voltage of the commercial power system G is determined in advance, the voltage may be used.

For example, the generated power Pi of the solar cell 10 is 4000 [W], and the voltage Vn (V
a = Vb = Vc = Vd = Ve) is 200 [V], and the ratio (ra: rb: rc: rd: re) of the distribution ratio to each consumer 2a to 2e is 1/8: 1/8: In the case of 1/8: 1/8: 4/8, the output current command values Ita to Itd are as follows.
Ita = ra × Pi / Va = 2.5 [A]
Itb = rb × Pi / Vb = 2.5 [A]
Itc = rc × Pi / Vc = 2.5 [A]
Itd = rd × Pi / Vd = 2.5 [A]
It = rb × Pi / Ve = 10 [A]

When the output current command values Ita to Ite are obtained, the control circuit 44 outputs the output current command values Ita to
A PWM signal is generated so that the inverter circuits 42a to 42e output voltages such that the difference between the Ite and the output currents Ia to Ie of the inverter circuits 42a to 42e becomes zero, and the PWM signals are generated in the switching elements of the inverter circuits 42a to 42e. Supply. Thus, each inverter circuit 42a
To 42e are supplied to each customer 2a to 2d and the commercial power system G with AC power distributed at a predetermined distribution ratio ra to re. Thus, each inverter circuit 42a-42.
The plurality of inverter circuits 42a to 42e are individually operated so that electric power based on the output currents Ia to Ie of e is supplied to the respective consumers 2a to 2e based on a predetermined distribution ratio ra to re.

The control circuit 44 (also serving as a transmission unit and a reception unit) is connected to the Internet (not shown), and information such as a power purchase fee or a power sale fee can be obtained from an electric power company or the like via this Internet. It is configured. The control circuit 44 changes the distribution ratio ra to re according to information that the communication circuit 45 obtains from the Internet.

In this embodiment, as this information, the communication circuit 45 receives a power selling fee for each time zone.
Then, the control circuit 44 generates power from the solar cell 1 that is distributed to the second inverter circuit 42e in the time zone in which the power sale fee is higher than the time zone in which the power sale fee is low. The distribution ratio re is set so that the power is increased.

For example, there is a possibility that the electricity bill is set high in a time zone when the power demand is high. FIG. 2 is a diagram showing a power selling fee for each time zone. (A) shows the summer season, and the power peak is around noon (13:00:00 to 16:00), so the unit price of the power selling fee for that time zone is set higher than other time zones (for example, , The unit price is 30 yen / k during the high power unit price
Wh, the unit time is set to 10 yen / kWh or the like in the low time zone). (B) shows the winter season, when the power peak is in the morning (6: 00 to 8:00) and in the evening (16: 00 to 18).
0:00), when the power selling unit price for that time zone is set higher than the other time zones (for example, when the power selling power unit price is high, the unit price is 30 yen / kWh, a low time The band is an example of setting the unit price to 10 yen / kWh).

When such information is received by the communication circuit 45, the control circuit 44, for example, sets the ratio of the distribution ratio in the time zone where the power selling power unit price is low (ra: rb: rc: rd: re) to 2/8: 2
/ 8: 2/8: 2/8: 0/8, and the ratio of the distribution ratio in the time zone when the power selling unit price is high (
(ra: rb: rc: rd: re) is set to 1/8: 1/8: 1/8: 1/8: 4/8. If it does in this way, the electric power (electric power sold directly) will be directly supplied from the second inverter circuit 43d to the commercial electric power system in the time zone when the electric power selling power unit price is high.

Further, the control circuit 44 uses the consumers 2a to 2d when the power supplied from the first inverter circuits 42a to 42d to the consumers 2a to 2d is larger than the self-consumed power in the consumers 2a to 2d.
The power supply to is reduced.

Specifically, the reverse power flow detectors 45a to 45 are provided on the commercial power system G side of the consumers 2a to 2d, and the reverse power flow (that is, supplied to the consumers 2a to 2d from the first inverter circuits 42a to 42d). The control circuit 44 is informed that the power to be consumed is greater than the power consumed by the consumers 2a to 2d). In response to this, the control circuit 44 may decrease the distribution ratio of the first inverter circuit in which the reverse power flow is detected, and increase the distribution ratio re of the second inverter circuit 42e by the decreased amount. Even if adjustment is not performed according to the distribution ratio, the current command values Ita to Itd of the first inverter circuit in which the reverse power flow is detected can be reduced, and the current command value Ite of the second inverter circuit 42e can be increased by the reduced amount. good.

As described above, according to the present embodiment, the owner of the power conversion system 1 and the consumers 2a to 2d.
Even if the users are different, since the first inverter circuits 42a to 42d supply power to the consumers, the users of the consumers 2a to 2d can use the generated power of the solar cell 10, By causing the inverter circuit 42e of 2 to reversely flow to the commercial power system G, the owner of the power conversion system 1 can use the generated power of the solar cell in the form of selling power to the commercial power system G.

Moreover, when the owner of the power conversion system 1 and the users of the consumers 2a to 2d are different, if the owner of the power conversion system 1 is the owner of the consumers 2a to 2d, the generated power of the solar cell 10 is obtained. It can appeal to consumers 2a-2d that it can be utilized.

Further, when the power supplied from the first inverter circuits 42a to 42d is larger than the self-consumed power in the consumers 2a to 2d, the power supply to the consumers 2a to 2d is reduced, and the second inverter circuit 42e. Therefore, more reverse power can be sold to the commercial power system G while supplying power to the consumers 2a to 2d.

In addition, since the second inverter circuit 42e employs a power that can be output more than the first inverter circuits 42a to 42d, the first inverter circuits 42a to 42d.
However, it is not necessary to reduce the output of the second inverter circuit 42e, and more power generated by the solar battery 10 can be sold to the commercial power system G.

Further, according to the present invention, the distribution ratios ra to re are changed so that more power can be output from the second inverter circuit 42e when the power selling fee is high (time zone). This
While the customer 2a uses the power generated by the solar cell 1, the power generated by the solar cell 1 can be sold at an average price as high as possible.

As mentioned above, although one Embodiment of this invention was described, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

For example, in the present embodiment, the solar cell 10 installed on the roof is used as a common generator. For example, a plurality of solar cells 1 are provided in different places, and the generated power of these solar cells 10 is collected. The generated power of the combined solar cell 10 is used as the first inverter circuits 42a to 42a-4.
When distributing in 2d, it can be seen that a common generator is used.

For example, in this embodiment, although the solar cell 10 was used as a generator, it is possible to use various generators, such as a fuel cell, a storage battery, a wind power generator, and an engine generator.

In addition, for example, when the power selling fee is high (time zone), the distribution ratio ra to re is changed so that more power can be output from the second inverter circuit 42e, but when the power selling fee is high (time zone) ) And a distribution ratio r so that more power can be output from the first inverter circuit 42e.
a to re may be changed.

In particular, if the customer is a residence, the time of the power peak in winter (Fig. 2
)), The customer needs electric power. Further, when the power selling fee is high, the power selling fee can be secured even with a small amount of power. Therefore, after securing a certain amount of electricity sales,
A large amount of necessary power can be provided to consumers.

DESCRIPTION OF SYMBOLS 1 Power conversion system 2 Consumer G Commercial power grid 10 Solar cell 11 Power converter 41 Booster circuit 42 Inverter circuit 43 System interconnection relay (switch)
44 Control circuit

Claims (4)

The electric power generated by the generator is distributed to a plurality of outputs using the first inverter circuit and the second inverter circuit, the output of the first inverter circuit is supplied for self-consumption within the consumer, and the second
A power conversion system characterized by causing the output of the inverter circuit to flow backward to the commercial power system. The first inverter circuit and the second inverter circuit according to the conversion of the unit price obtained by the control circuit in the control circuit configured to be able to obtain information on the unit price of power sold to flow backward to the commercial power system A power conversion system characterized by changing a ratio of power to be distributed to each other. When the power supplied from the first inverter circuit is larger than the self-consumed power in the consumer, the power supply to the consumer is reduced and the power supplied from the second inverter circuit is increased. The power conversion system according to claim 1 or claim 2. The power conversion system according to claim 3, wherein the second inverter circuit can output a larger amount of power than the first inverter circuit.

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