JP5903592B2 - Power conversion system - Google Patents

Description

  The present invention relates to a power conversion system that converts power generated by a generator into AC power and supplies the AC power to 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 2003-134672 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 converts the generated power of the solar cell into AC power by an inverter circuit. The converted AC power is distributed to each consumer using a branch wiring that branches from the output side of the inverter circuit. Each branch line connected to each consumer is provided with a power controller, and when distributing power, the power controller controls on / off of the power flowing through the branch line to each customer. The power of the above-described distribution ratio is distributed. Thus, when distributing electric power to each consumer using a branch wiring, since an inverter circuit can also be shared, an apparatus can be comprised cheaply.

  However, when power is distributed to each consumer using a branch wiring that branches from the output side of the inverter circuit as in a conventional power conversion system, even if the load used by the consumer varies slightly. Since the electric power supplied to the consumer fluctuates, it is difficult to distribute the electric power to the consumer at a predetermined distribution ratio, and there is a possibility that unfairness may occur in the electric power distribution.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a power conversion system that can suppress unfairness caused by power distribution while configuring the system at a low cost.

  In order to achieve the above object, a power conversion system of the present invention includes an inverter circuit that converts DC power into AC power, and converts the AC power output from the inverter circuit to a plurality of consumers. In the system, a plurality of branch wirings having one end connected to the output side of the inverter circuit and the other end connected to the plurality of consumers, and connection / opening of the lines of the branch wiring respectively interposed in the branch wirings And a switch connected to the plurality of consumers in order by connecting / releasing the plurality of switches in a predetermined order and connected to the connected switches. When the amount of the AC power supplied to the power supply reaches a predetermined value, the connected switch is opened and the next switch is connected.

  According to the present invention, power is distributed to each consumer using the branch wiring, and AC power is sequentially supplied to a plurality of consumers using an inexpensive configuration that shares the inverter circuit. In addition, when the amount of AC power supplied to a consumer reaches a predetermined value, the switch in the connected state connected to this consumer is opened and the next sequential switch is connected. . As a result, AC power can be supplied to each consumer at a predetermined distribution ratio of power, so that unfairness due to power distribution can be suppressed while the system is configured at low cost.

  In the above-described invention, the predetermined value is determined for each consumer.

  In the above-mentioned invention, the customer is notified of the time when the switch connected to the customer is closed and the AC power is supplied.

In the above-mentioned invention, the branch wiring is connected to a commercial power system that supplies power to the consumer,
A reverse flow detector for detecting reverse flow from the consumer to the commercial power system, and when detecting reverse flow by the reverse flow detector, connecting at least one open switch; It is characterized by.

  In the above-mentioned invention, the switch connected when the reverse power flow is detected is a switch in the following order.

The power distributor of the present invention is connected to an inverter circuit that converts DC power into AC power, and in the power distributor that supplies the AC power to a plurality of consumers, one end is connected to the output side of the inverter circuit A plurality of branch wirings each having the other end connected to the plurality of consumers,
A switch for connecting / opening a line of the branch wiring interposed between the branch wirings,
The AC power is supplied to the plurality of consumers in order by connecting / releasing the plurality of switches in a predetermined order, and the AC power supplied to the consumers connected to the connected switch When the amount of electric power reaches a predetermined value, the connected switch is opened and the next sequential switch is connected.

  The power conversion system of the present invention has an inverter circuit that converts DC power into AC power, and in the power conversion system that supplies AC power output from the inverter circuit to a plurality of consumers, one end of the inverter circuit A plurality of branch wirings connected to the output side of the power supply and connected to the plurality of consumers at the other end, and a selector for selecting a consumer that supplies AC power through the branch wiring. When the AC power supplied to the house satisfies a predetermined condition, the consumer supplying the AC power is changed.

  Moreover, in the above-mentioned invention, the predetermined condition is the accumulation of the AC power supplied to the consumer or the time during which the AC power is supplied to the consumer.

Moreover, in the above-mentioned invention, the selector is configured to be able to select a plurality of consumers.

  An object of the present invention is to provide a power conversion system that can suppress unfairness due to power distribution while configuring the system at low cost.

It is a schematic diagram which shows the Example of a power conversion system. It is an electric circuit diagram which shows the Example of a power conversion system. It is a figure which shows the operation | movement flowchart at the time of connecting / releasing a some relay for connection.

  Hereinafter, embodiments 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, 2b is supplied with AC power from the commercial power system 4, and a common power conversion system 1 is provided for these consumers 2a, 2b.

  The power conversion system 1 receives supply of direct-current power from a common solar cell 3 (generator) to consumers 2a and 2b. In the present embodiment, the consumers 2a and 2b are constituted by detached houses, and the consumers 2a and 2b are neighboring houses, respectively. The solar cell 3 is installed on the roof of the consumer 2a, and the power conversion system 1 is arranged beside the first floor (customer 2a) of this building. The generated power of the solar cell 3 is input to the power conversion system 1, and the power conversion system 1 distributes and supplies this generated power to each consumer 2a, 2b. Note that the consumers 2a to 2c are not limited to neighboring single-family houses, and may be constituted by, for example, an apartment house such as an apartment or an apartment. Moreover, although the solar cell 3 is installed on the roof of the consumer 2a, you may make it install in the vicinity of the consumer 2a, 2b.

  Each consumer 2a, 2b has distribution boards 21a, 21b. The distribution boards 21a and 21b receive the AC power supplied from the commercial power system 3 and the AC power supplied from the power converter, and superimpose these AC powers and supply them to the loads 25 of the consumers 2a and 2b. To do.

  In addition, reverse power flow detectors 22a and 22b, power meters 23a and 23b, and power meters 24a and 24b are respectively provided on the side of the commercial power system 3 of the distribution boards 21a and 21b of the consumers 2a and 2b. Yes. The electricity purchase meters 23a and 23b detect the electric power supplied from the commercial power system 3 to the consumers 2a and 2b. The detected power is used to calculate a purchased power charge. The electricity sales meters 24a and 24b detect the electric power supplied to the commercial power system 3 from the consumers 2a and 2b. The detected power is used to calculate a power selling power charge.

  Thus, each consumer 2a, 2b is individually provided with a power purchase meter 23a, 23b and a power purchase meter 24a, 24b, and is configured to be able to individually buy and sell power with a power company. Has been.

  The reverse power flow detectors 22 a and 22 b detect the power flowing backward from the consumers 2 a and 2 b to the commercial power system 4 and notify the power conversion system 1. The power conversion system 1 controls the operation of the power conversion system 1 based on this notification. Details of the control will be described later.

  The consumers 2a and 2b are provided with display monitors 26a and 26b, respectively, so that the usage status of the power of the consumers 2a and 2b can be displayed.

  Next, the power conversion system 1 will be described in detail with reference to the drawings. FIG. 2 is an electric circuit diagram of the power conversion system. As shown in this figure, the power conversion system 1 includes a booster circuit 11, an inverter circuit 12, interconnection relays 13a and 13b (switches), a control circuit 14, an input current sensor 51, an input voltage sensor 52, and an output current sensor. 53a, 53b and output voltage sensors 54a, 54b. Further, the booster circuit 11, the inverter 12c, the grid interconnection relays 13a and 13b, the control circuit 14, the input current sensor 51, the input voltage sensor 52, the output current sensors 53a and 53b, and the output voltage sensors 54a and 54b are a common casing. Are arranged in a common place (here, the side of the customer 2c).

  The booster circuit 11 is connected between the solar cell 3 and the inverter circuit 12 and boosts the voltage of the solar cell 3. The booster circuit 11 includes a reactor, a switching element such as IGBT or FET, 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 3. 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 11 periodically conducts / cuts off the switch element, and sets the ratio of conducting the switch element for each period (hereinafter referred to as the ON ratio), for example, thereby setting the voltage of the solar cell at a desired boost ratio. Boost and output to both ends of the capacitor.

  The inverter circuit 12 converts the power generated by the common solar cell 3 input via the booster circuit 11 into AC power. In addition, one end of a plurality of branch lines La and Lb is connected to the output side of the inverter circuit 12, and the other end of the branch lines La and Lb is connected to a plurality of consumers, respectively. As a result, the AC power converted by the inverter circuit 12 is supplied to the consumers 2a and 2b via the branch lines La and Lb.

  The inverter circuit 12 has a bridge circuit composed of four switch elements such as IGBT and FET, and a filter circuit composed of two reactors and a capacitor. In the bridge circuit of the inverter circuit 12, 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. In the filter circuit, one end of each of the two reactors is connected by a capacitor, and the other end of each of the reactors is connected to the AC side of the bridge circuit. The inverter circuit 12 generates alternating-current power having a waveform synchronized with the commercial power system by conducting / cutting off the four switch elements using a predetermined PWM (Pulse Width Modulation) signal, to the consumers 2a and 2b. Supply.

  The interconnection relays 13a and 13b are interposed in the branch lines La and Lb, respectively, and connect / release the lines of the branch lines La and Lb. As a result, the AC power output from the inverter circuit 12 is supplied to the consumers 2a and 2b connected to the connected relays 13a and 13b and connected to the open connected relays 13a and 13b. AC power output from the inverter circuit 12 is cut off to the consumers 2a and 2b.

  The selector relays 13a and 13b operate to operate a selector that selects consumers who connect / open the branch lines La and Lb to supply AC power. However, the present invention is not limited to this, and a consumer may be selected using a rotary changeover switch configured to switch between a common contact and a contact connected to each consumer. A plurality of consumers may be selected at the same time.

  The input current sensor 51 is provided on the input side of the booster circuit 11 and detects a DC input current Ii input from the solar cell 3 to the booster circuit 11. The input voltage sensor 51 is provided on the input side of the booster circuit 11 and detects a DC input voltage input from the solar cell 3 to the booster circuit 11. Further, the branch wirings La and Lb are provided with output current sensors 53a and 53b, respectively, which detect instantaneous output currents Ioa and Iob of the branch wirings La and Lb. Further, output voltage sensors 54 a and 54 b are provided on the output side of the inverter circuit 12 to detect instantaneous output voltages Voa and Vob of the respective inverter circuits 12.

The detected input current Ii and input voltage Vi are input to the control circuit. The output currents Ioa and Iob and the output voltages Voa and Vob are input to the control circuit and executed in the control circuit 14 by using the output currents Ioa and Iob and the output voltages Voa and Vob input in the past. The value (or average value) is calculated. Hereinafter, the effective values of the output currents Ioa and Iob are set as output currents Ia and Ib, and the effective values of the output voltages Voa and Vob are set as Va and Vb. The input current Ii, the input voltage Vi, the output currents Ia and Ib, and the output voltages Va and Vb are used for controlling the operation of the power conversion system 11.

  The control circuit 14 is composed of, for example, a microcomputer, and controls the operation of the booster circuit 11, the operation of the inverter circuit 12, and the operation of the interconnection relays 13a and 13b.

The control circuit 14 controls the ON ratio of the booster circuit 11 so that the generated power of the solar cell 3 (input power to the booster circuit 11) is maximized. Specifically, the generated power of the solar cell 3 input to the booster circuit 11 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 14 generates a PWM signal for turning on / off the switch element of the inverter circuit 12. Specifically, the control circuit 14 calculates the output current command value It of the inverter circuit 12 and simplifies the description by assuming that the commercial system voltage supplied to each consumer is the same, and detects the detected output current ( A PWM signal that outputs the output voltage of the inverter circuit 12 is generated so that Ia + Ib) matches the output current command value.

  The control circuit 14 generates a signal for connecting / releasing the interconnection relays 13a and 13b and controls the interconnection relays 13a and 13b to be in a desired state (connection state or open state). At this time, the control circuit 14 connects / releases the plurality of interconnection relays 13a, 13b in a predetermined order, thereby supplying the AC power output from the inverter circuit 13 to the plurality of consumers 2a, 2b in order. . At this time, the control circuit 14 opens the connected switch when the amount of AC power supplied to the consumer connected to the connected relays 13a and 13b reaches a predetermined value. Then, connect the next switch in the connected state. The selected consumer is not limited to the amount of AC power, but may be configured to change over time.

  FIG. 3 shows an operation flowchart when connecting / releasing a plurality of interconnection relays. In this flowchart, for convenience sake, a numerical value (1, 2,... N) is used for i. When the control circuit 14 starts control to connect / release the interconnection relays 13a and 13b in order, 1 is input to i (step S11), and the i-th interconnection relay is brought into a connected state (step S12). .

  Next, the control circuit 14 detects the current I [i] of the branch wiring in which the i-th interconnection relay is interposed (step S13), and the electric power P supplied to the customer connected to this branch wiring. [i] is calculated (step S14). Since the electric energy P [i] is an integrated value of electric power, it can be obtained by P [i] = P [i] + I [i] × V × T. Here, V represents the voltage of the commercial power system, and T represents the sampling time of the current I [i]. However, instead of V, the voltage V [i] of the branch wiring in which the i-th interconnection relay is interposed can also be used.

  The calculated power amount P [i] is compared with a predetermined value Pth [i], and it is determined whether or not the power amount P [i] is larger than the predetermined value Pth [i] (step S15). If P [i] is not larger than the predetermined value Pth [i], the process proceeds to step S13, and steps S13 to S15 are repeated until P [i] becomes larger than the predetermined value Pth [i]. When P [i] is larger than the predetermined value Pth [i], the i-th interconnection relay is opened (step S16), the electric energy P [i] is reset to zero (step S17), and i is set to 1. Is added (step S18).

  After step S18, the control circuit 14 determines whether i is larger than n (step S19). When i is larger than n, the power is supplied to n consumers. Therefore, the process returns to step S11 to reset i to 1. And power can be sequentially supplied again from the 1st consumer by performing Step S12 and after. When i is not larger than n, the control circuit 14 does not supply power to all n consumers, and therefore the control circuit 14 returns to step S12 and outputs the alternating current output from the inverter circuit 12 to the next consumer. Supply power.

  In the present embodiment, since there are two interconnection relays 13a and 13b, n = 2, and when the code [1] is represented by the code a and the code [2] is represented by the code b, the interconnection relay 13a is first. The relay 13 [1] to be connected and the relay 13b to be connected second can be viewed as the relay 13 [2] to be second connected. Similarly, the current, voltage, power amount, etc. can be read by replacing the signs. In this way, the control circuit 14 supplies the AC power output from the inverter circuit 12 to the consumers 2a and 2b in order. At this time, since the ratio of the predetermined value Pth [i] is the ratio of the amount of electric power to be distributed, it may be determined based on the investment ratio of the consumers 2a and 2b. Thereby, electric power can be distributed fairly to each consumer.

  The control circuit 14 has a function as a communication circuit that communicates with the display monitors 26a and 26b of the consumers 2a and 2b. This communication can be performed by using an Internet line, a serial communication line, or the like.

  Moreover, the control circuit 14 uses this communication function, and when the interconnection relays 13a and 13b connected to the consumer are in an open state with respect to the consumers 2a and 2b, the interconnection is next performed. The relays 13a and 13b are closed and the AC power output from the inverter circuit 12 is notified. This time is, for example, how many times the supply of AC power output from the inverter circuit 12 is started, how long the supply of AC power output from the inverter circuit 12 is started, etc. is there.

  As shown in the description of the flowchart above, the control circuit 14 supplies power to which number of consumers as to which supply of the AC power output from the inverter circuit 12 is started. I can remember it, so I can find it based on this.

  In addition, regarding how long the supply of the AC power output from the inverter circuit 12 is started, the time when the power amount P [i] reaches Pth [i] in each consumer in the past, This can be determined by considering whether the current amount of power has been supplied in a certain amount of time.

  In this way, the control circuit 14 transfers (notifies) the obtained time when the AC power output from the inverter circuit 12 is supplied to the display monitors 26a and 26b provided in the respective consumers 2a and 2b. Display).

  The control circuit 14 is configured to be able to receive a signal indicating that a reverse power flow has been detected from the reverse power flow detectors 22a and 22b of the consumers 2a and 2c. Upon receiving this signal, the control circuit 14 connects at least one currently released interconnection relay to the connected state, and uses the AC power output from the inverter circuit 12 in the plurality of consumers 2a and 2b as much as possible. It is configured to be able to. As a result, when the cost of selling the generated power in-house is lower, such as when the power sale fee of the commercial power system 4 is larger than the power purchase fee of the commercial power system 4, a plurality of as many as possible Low-cost electric power (generated electric power of the solar cell 1) can be used in the consumers 2a and 2b. In this embodiment, there are two customers, but the same applies to the case of three or more customers.

  Further, the interconnection relay to be connected when a reverse power flow is detected may be the next interconnection relay. And the control circuit 14 memorize | stores the electric energy of the alternating current power supplied from the inverter circuit 12 to the consumer connected to the relay for interconnection | linkage connected at this time, and this inverter is connected to this consumer next in order. When AC power is to be supplied from the circuit 12, the detection of the power amount may be restarted from the stored power amount. By doing in this way, the alternating current power which the inverter circuit 12 outputs can be supplied to consumers 2a and 2b in order, considering the electric power supplied when the reverse power flow is detected (regular).

  As described above, according to the embodiment of the present invention, power is distributed to the consumers 2a and 2c using the branch wirings La and Lb, and a plurality of components are sequentially used by using an inexpensive configuration that shares the inverter circuit 12. AC power was supplied to the consumers 2a and 2b. Further, when the amount of AC power supplied to the consumers 2a and 2b reaches a predetermined value, the connected relay connected to the consumer is opened to use the next sequential interconnection. The relay was connected. As a result, AC power can be supplied to each consumer 2a, 2c at a predetermined distribution ratio of electric energy, so that unfairness due to power distribution can be suppressed while the system is configured at low cost. Can do.

  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 this embodiment, the electric energy P [i] is compared with a predetermined value Pth [i], and the AC power output from the inverter circuit is supplied to the next consumer. In any case, it can be said that even if an equivalent is used, the electric energy P [i] is used. For example, as equivalent to the electric energy P [i], the integrated value of the current I [i], the integrated value of the current I [i] × T, the integrated value of the current I [i] × V, etc. Can be used.

  Further, for example, in the present embodiment, an example of the power supply system 1 including the branch wirings La and Lb and the interconnection relays 13a and 13b is given. However, the branch wirings La and Lb and the interconnection relays 13a and 13b are given. Can be configured as a power distributor by simply attaching the power distributor to the output side of the existing power conditioner, thereby easily configuring the power supply system 1 described in the present embodiment. it can.

  Further, for example, in this embodiment, when a reverse power flow is detected in a consumer who receives the supply of power generated by the solar battery, the next relay relay is closed to supply power to other consumers. However, a storage battery may be provided for each consumer, and when a reverse power flow is detected, the storage battery may be charged with electric power. The electric power charged in the storage battery may be used after the connected relay for connection is closed. Even in this case, when the cost of selling the generated power in-house is lower, such as when the power selling fee of the commercial power system 4 becomes larger than the power purchase fee of the commercial power system 4, It is possible to use low-cost power (generated power of the solar cell 1) in the plurality of consumers 2a and 2b as much as possible.

In this case, the power distributor is connected to an inverter circuit of a power conditioner that converts DC power into AC power, and supplies the AC power to a plurality of consumers. In addition, the power distributor includes a plurality of branch lines each having one end connected to the output side of the inverter circuit and the other ends connected to the plurality of consumers, and a line of the branch lines respectively interposed in the branch lines. And a switch for performing connection / release. The power distributor supplies the AC power output from the inverter circuit to the plurality of consumers in order by connecting / releasing the plurality of switches in a predetermined order, and is connected to the connected switch. When the amount of AC power supplied to the customer reaches a predetermined value, the connected switch is opened and the next sequential switch is connected.

DESCRIPTION OF SYMBOLS 1 Power conversion system 2 Consumer 3 Solar cell 4 Commercial power system 11 Booster circuit 12 Inverter circuit 13 Relay for connection (switch)
14 Control circuit 21 Distribution board 22 Reverse power flow detector 23 Power meter 24 Power meter 25 Load 51 Input current sensor 52 Input voltage sensor 53 Output current sensor 54 Output voltage sensor

Claims (8)

In a power conversion system that has an inverter circuit that converts DC power into AC power, and supplies the AC power output from the inverter circuit to a plurality of consumers,
A plurality of branch wirings connected at one end to the output side of the inverter circuit and connected at the other end to the plurality of consumers, respectively;
A switch for connecting / opening a line of the branch wiring interposed between the branch wirings,
The AC power is supplied to the plurality of consumers in order by connecting / releasing the plurality of switches in a predetermined order, and the AC power supplied to the consumers connected to the connected switch A power conversion system comprising: opening a connected switch and connecting a next sequential switch when the amount of power reaches a predetermined value. The power conversion system according to claim 1, wherein the predetermined value is determined for each consumer. 3. The power conversion system according to claim 1, wherein a time when the switch connected to the consumer is closed and the supply of the AC power is performed is notified to the consumer. 4. . The branch wiring is connected to a commercial power system that supplies power to the consumer,
A reverse flow detector for detecting the reverse flow of power from the consumer to the commercial power system,
The power conversion system according to any one of claims 1 to 3, wherein when the reverse power flow is detected by the reverse power flow detector, at least one open / closed switch is connected. 5. The power conversion system according to claim 4, wherein the switch connected when the reverse power flow is detected is a switch in the following order. In a power distributor that is connected to an inverter circuit that converts DC power to AC power and supplies the AC power to a plurality of consumers,
A plurality of branch wirings, one end of which is connected to the output side of the inverter circuit and the other end of which is connected to each of the plurality of consumers;
A switch for connecting / opening a line of the branch wiring interposed between the branch wirings,
The AC power is supplied to the plurality of consumers in order by connecting / releasing the plurality of switches in a predetermined order, and the AC power supplied to the consumers connected to the connected switch A power distributor comprising: opening a connected switch and connecting a next sequential switch when the amount of power reaches a predetermined value. In a power conversion system that has an inverter circuit that converts DC power into AC power, and supplies the AC power output from the inverter circuit to a plurality of consumers,
A selector that selects one of the plurality of branch wires connected at one end to the output side of the inverter circuit and the other end connected to the plurality of consumers, and the customer that supplies the AC power through the branch wires. And comprising
The power conversion system according to claim 1, wherein the selector changes the consumer supplying the AC power when the amount of the AC power supplied to the consumer reaches a predetermined value . The power conversion system according to claim 7 , wherein the selector is configured to be able to select a plurality of consumers.

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