Ac-DC power conversion device and power system

Abstract

An AC-DC power conversion device 100 includes: a first terminal 11 connected to a main wiring line; a second terminal 12 connected to a sub-wiring line; a third terminal 13 connected to a storage battery 110; an inverter 20 provided between the third terminal 13 and the first terminal 11 and between the third terminal 13 and the second terminal 12; a first current sensor 31 provided between the inverter 20 and the first terminal 11; and a second current sensor 32 provided between the inverter 20 and the second terminal 12. A current is controlled on the basis of a detection result by the first current sensor 31. A current is controlled on the basis of a detection result by the second current sensor 32.

Description

AC-DC power conversion device and power system

[0001] The present invention relates to an AC-DC power conversion device and a power system using the AC-DC power conversion device.

[0002] Conventionally, AC-DC power converters have been used to supply power to AC loads. For example, Japanese Patent Application Laid-Open No. 2003-111426 discloses an AC-DC power converter that uses an additional current fluctuation-containing signal generating means, a sine wave generator, and a power converter to compensate for the lack of response due to a response delay to load fluctuations in an engine generator, which has a slow response speed, using power from a storage battery.

[0003] In the conventional configuration, a delay circuit is provided to deal with the response delay of the AC power supply, and it is not possible to supply a current that perfectly matches the current consumption of the load.

[0004] The present invention provides an AC-DC power conversion device that can quickly follow fluctuations in current flowing through a load, even when such fluctuations occur, compared to conventional aspects, and a power system that uses the AC-DC power conversion device.

[0005] [Concept 1] An AC-DC power conversion device according to the present invention includes: a first terminal connected to a main distribution line; a second terminal connected to a sub-distribution line; a third terminal connected to a storage battery; inverters provided between the third terminal and the first terminal and between the third terminal and the second terminal; a first current sensor provided between the inverter and the first terminal; and a second current sensor provided between the inverter and the second terminal, and may control a current based on a detection result by the first current sensor, and may control a current based on a detection result by the second current sensor.

[0006] [Concept 2] An AC-DC power conversion device according to the present invention comprises: a first terminal connected to a main distribution line; a second terminal connected to a sub-distribution line; a third terminal connected to a storage battery; an inverter having a current detector, which is provided between the third terminal and the first terminal and between the third terminal and the second terminal; and a first current sensor provided between the inverter and the first terminal, wherein the AC-DC power conversion device controls a current based on a detection result by the first current sensor, and may control a current based on a difference between a current value detected by the current detector and a current value detected by the first current sensor.

[0007] [Concept 3] In the AC-DC power conversion device according to Concept 1 or 2, a first loop wiring connected to the inverter may be provided in a first wiring provided between the inverter and the first terminal, and a negative feedback loop circuit may be configured by the first wiring and wiring including the first loop wiring.

[0008] [Concept 4] In the AC-DC power conversion device according to any one of Concepts 1 to 3, a second loop wiring connected to the inverter may be provided in a second wiring provided between the inverter and the second terminal, and a positive feedback loop circuit may be configured by a wiring including the second wiring and the second loop wiring.

[0009] [Concept 5] In the AC-DC power conversion device according to any one of Concepts 1 to 4, a control current signal may be input to the inverter, and an AC instantaneous current value may be calculated based on the control current signal to control the current at the first terminal.

[0010] [Concept 6] In the AC-DC power conversion device according to any one of Concepts 1 to 5, a first wiring provided between the inverter and the first terminal may include a phase synchronization wiring connected to the inverter, and a phase synchronization circuit may be provided on the phase synchronization wiring.

[0011] [Concept 7] In the AC-DC power converter according to any one of Concepts 1 to 6, the main distribution line may be connected to a power distribution system, and the sub-distribution line may be connected to a consumer load or a generator.

[0012] [Concept 8] The AC-DC power conversion device according to any one of Concepts 1 to 7 may be used in a single-phase three-wire AC power distribution system, a three-phase three-wire AC power distribution system, or a three-phase four-wire AC power distribution system, and may balance the relative current values ​​at the first terminals by controlling the current based on a detection result by the second current sensor, or by controlling the current based on a difference between a current value detected by the current detector and a current value detected by the first current sensor.

[0013] [Concept 9] A power system according to the present invention includes a plurality of AC / DC power conversion devices, each of which is an AC / DC power conversion device according to any one of Concepts 1 to 7, and when actually supplying power from one AC / DC power conversion device to another AC / DC power conversion device, reservation information for the amount of power may be written in advance, and the actual amount of power supplied and the amount of power demanded and supplied may be written to the blockchain.

[0014] According to the present invention, it is possible to provide an AC-DC power conversion device that can quickly follow fluctuations in current flowing through a load, even when such fluctuations occur, as compared to conventional aspects, and a power system that uses the AC-DC power conversion device.

[0015] 1 is a schematic diagram showing an example of the configuration of an AC-DC power converter according to an embodiment of the present invention. It is a diagram showing the voltage (1) at the first terminal, the receiving current (2) in the first wiring, the load current (3), and the inverter current (4) of the AC-DC power converter according to an embodiment of the present invention. It is a schematic diagram showing the configuration of an AC-DC power converter according to a reference example in which the current flowing from the storage battery is not controlled based on the detection result by the second current sensor. It is a diagram for explaining that, in the reference example shown in FIG. 3, the current at the first terminal temporarily increases when the load is turned on and the current at the first terminal temporarily decreases when the load is turned off. It is a diagram showing the voltages at the first terminal and the second terminal when the current at the second terminal (load current) is suddenly changed as shown in FIG. 7 in the AC-DC power converter according to an embodiment of the present invention. It is a diagram showing the current at the first terminal when the current at the second terminal (load current) is suddenly changed as shown in FIG. 7 in the AC-DC power converter according to an embodiment of the present invention. It is a diagram showing the state in which the current at the second terminal (load current) is suddenly changed in the AC-DC power converter according to an embodiment of the present invention. 8 is a diagram showing an inverter current (storage current) when the current (load current) at the second terminal is suddenly changed as shown in FIG. 7 in an AC-DC power converter according to an embodiment of the present invention. A diagram showing an example of a power system using an AC-DC power converter according to an embodiment of the present invention. A schematic diagram showing another example of the configuration of an AC-DC power converter according to an embodiment of the present invention. A schematic diagram for explaining a case where a single-phase two-wire AC distribution system, a single-phase three-wire AC distribution system, or a three-phase three-wire AC distribution system is adopted in an AC-DC power converter according to an embodiment of the present invention.

[0016] In the present embodiment, "or" also means "and." For example, in the present embodiment, "A or B" means either "A, B, or A and B."

[0017] The AC-DC power conversion apparatus 100 of this embodiment has a first terminal 11 connected to a main distribution line, a second terminal 12 connected to a sub-distribution line, and a third terminal 13 connected to a storage battery 110. An inverter 20 is provided between the third terminal 13 and the first terminal 11 and between the third terminal 13 and the second terminal 12. A first current sensor 31 is provided between the inverter 20 and the first terminal 11. A second current sensor 32 is provided between the inverter 20 and the second terminal 12. The AC-DC power conversion apparatus 100 may control the current flowing from the storage battery 110 based on the detection result of the first current sensor 31. The AC-DC power conversion apparatus 100 may control the current flowing from the storage battery 110 based on the detection result of the second current sensor 32. The main distribution line connected to the first terminal 11 may be connected to a distribution system, and the sub-distribution line connected to the second terminal 12 may be connected to a load or a generator of a consumer (typically a home). Furthermore, the sub-distribution line connected to the second terminal 12 may be connected to a microgrid. The AC-DC power conversion apparatus 100 of this embodiment may be a bidirectional DC-AC power conversion apparatus. The inverter 20, the first current sensor 31, the second current sensor 32, etc. are housed in a housing 80. When the inverter 20 has a current detector 25 (see FIG. 10 ), the second current sensor 32 may not be provided or may be used in combination with the second current sensor 32, and the current flowing from the storage battery 110 may be controlled based on the difference between the current value detected by the current detector 25 and the current value detected by the first current sensor 31.

[0018] A first wiring 41 may be provided between the inverter 20 and the first terminal 11, and a second wiring 42 may be provided between the inverter 20 and the second terminal 12. A common wiring 45 may be provided between the first wiring 41 and the second wiring 42 and the inverter 20. A third wiring 43 may be provided between the inverter 20 and the third terminal 13.

[0019] The first wiring 41 may be provided with a phase synchronization wiring 46 connected to the inverter 20, and a phase locked loop (PLL) may be provided on the phase synchronization wiring 46. When such an embodiment is adopted, the voltage of the first terminal 11 is input to the phase locked loop (PLL), and a reference voltage waveform synchronized with the voltage is generated by the inverter 20 and output.

[0020] A control current signal may be input to inverter 20 from the outside via control current terminal 15, and an instantaneous AC current value, rather than an average value, may be calculated based on the control current signal, while controlling the current flowing from storage battery 110 so that the current value at first terminal 11 matches the current value determined by the control current signal. In this case, an AC current waveform serving as a control target value is generated in inverter 20 in accordance with the reference voltage waveform of the phase-locked loop. For example, if a control current signal is input to cause a 5 A current to flow from the main distribution line to first terminal 11, and a 10 A current flows from second terminal 12 to the sub-distribution line, the storage battery 110 will output a 5 A current, causing the current value received from the first terminal 11 to match the current value (5 A) determined by the control current signal ("10 A current flowing in the sub-distribution line" - "5 A current output from storage battery 110" = "5 A current flowing from the main distribution line to first terminal 11"). In this way, by controlling the current flowing through the first terminal 11 by the control current signal, the first terminal 11 can function as a constant current source (CC). A fourth wiring 44 may be provided between the inverter 20 and the control current terminal 15.

[0021] The first wiring 41 may be provided with a first loop wiring 51 connected to the inverter 20. In this case, a negative feedback loop circuit may be configured by wiring including the first wiring 41 and the first loop wiring 51. A current negative feedback loop may be formed by comparing the instantaneous current value read from the first current sensor 31 with an AC current waveform that is a control target value and instantaneously adjusting a control difference value. Feedback in which, when an increase (or decrease) in the output is reflected in the input, the fed-back signal shows an increase or decrease that is opposite to that of the input is called "negative feedback." For example, if the current received at the first terminal 11 from the main distribution line increases, the current flowing from the storage battery 110 is controlled to decrease accordingly.

[0022] The second wiring 42 may be provided with a second loop wiring 52 connected to the inverter 20. In this case, a positive feedback loop circuit may be configured by wiring including the second wiring 42 and the second loop wiring 52. A current positive feedback loop for the current negative feedback loop may be formed by comparing the instantaneous current value read from the second current sensor 32 with an AC current waveform that is a control target value and adding or subtracting the current. Feedback in which, when an increase (or decrease) in the output is reflected in the input, the fed-back signal shows the same increase or decrease as the input is called "positive feedback." For example, if the current flowing to the load via the second terminal 12 increases, the current flowing from the storage battery 110 is controlled to increase accordingly.

[0023] If such a current positive feedback loop is not formed, the current at the first terminal 11 may fluctuate due to a control current error at the first terminal 11. More specifically, the voltage and frequency at the first terminal 11 are generated by a large synchronous generator or the like connected to the main distribution line, so both voltage and frequency fluctuations are gradual and are externally controlled to stabilize them within the power grid. Therefore, a phase-locked loop based on this signal can also output a stable voltage waveform. On the other hand, current changes at the second terminal 12, which are added to the current negative feedback loop, become disturbances and result in unpredictable changes, causing the current at the first terminal 11 to fluctuate due to a control current error at the first terminal 11. In response to this, by positively feeding back the current value at the second terminal 12, which is a disturbance, based on the value detected by the second current sensor 32 and correcting the current change due to the disturbance in advance, the control current error can be minimized and the effect of current changes at the second terminal 12 on the current value at the first terminal 11 can be reduced.

[0024] The function of keeping the current at the first terminal 11 constant is realized by generating a voltage from the inverter 20 that is approximately equal to the voltage applied to the first terminal 11 and balancing the voltage. As a result, the voltage at the second terminal 12 follows the voltage at the first terminal 11.

[0025] Due to these functions, the first terminal 11 as seen from the main distribution line can be regarded as a constant current source (CC: Constant Current) as described above, and the second terminal 12 as seen from the sub-distribution line can be regarded as a constant voltage source (CV: Constant Voltage) that uses the voltage of the main distribution line as a reference.

[0026] FIG. 2 shows an example of voltage waveforms and current waveforms at various points. More specifically, it shows the voltage (1) at the first terminal 11 (shown as "main distribution voltage (1)" in FIG. 2), the received current (2) in the first wiring 41, and the load current (3) and inverter current (4) in the second wiring 42 synchronized with the main distribution voltage waveform. (1) to (4) in FIG. 2 correspond to (1) to (4) in FIG. 1. This also applies to FIGS. 5 to 8.

[0027] In Figure 2, the receiving current and the inverter current at the first terminal 11 are the same until near the center of the positive voltage cycle. However, when the load is turned on (see "Load ON" on the left side of Figure 2), the current (load current (3)) flowing to the load via the second terminal 12 increases, and the inverter current (4) decreases accordingly. In other words, the value of the receiving current (2) is set to a predetermined value by reducing the current (4) flowing to the inverter by the amount of the increase in the current (3) flowing to the sub-distribution line. Also, when the load is turned off near the center of the next positive voltage cycle (see "Load OFF" on the right side of Figure 2), the inverter current becomes equal to the current at the first terminal 11, is smoothed as the inverter current, and becomes the charging current for the storage battery 110. In other words, the value of the receiving current (2) is set to a predetermined value by increasing the current (4) flowing to the inverter by the amount of the decrease in the current (3) flowing to the sub-distribution line.

[0028] If the control current value of the first terminal 11 is set to 0 A, when the load is turned on or off, the current is entirely supplied from the storage battery 110 via the inverter 20 .

[0029] According to this embodiment, the voltage at the second terminal 12 is the same as the voltage at the first terminal 11, so the sub-distribution voltage can always be regarded as the same voltage source as the main distribution line voltage.

[0030] As a reference example, a configuration will be described in which the current flowing from the storage battery 110 is not controlled based on the difference between the detection result by the second current sensor 32 (see FIG. 1 ) or the current value detected by the current detector 25 (see FIG. 10 ) and the current value detected by the first current sensor 31. In the configuration shown in FIG. 3 , if there is a current fluctuation due to the load, the inverter circuit can follow the fluctuation slowly but not instantaneously. Therefore, as shown in the waveforms in FIG. 4 , when the load is turned on, the current flowing through the first terminal 11 temporarily increases to follow the load, while when the load is turned off, the current flowing through the first terminal 11 temporarily decreases as a result. When a microgrid is configured using only the inverter 20, such instantaneous current increases and phenomena hinder simultaneous balancing control.

[0031] In contrast, when the current flowing from the storage battery 110 is controlled based on the detection result by the second current sensor 32 or the difference between the current value detected by the current detector 25 and the current value detected by the first current sensor 31, the sinusoidal wave voltage at the second terminal 12 is equivalent to the sinusoidal wave voltage at the first terminal 11 as shown in Fig. 5, and even if the current (load current) at the second terminal 12 suddenly changes as shown in Fig. 7, the current (received current) at the first terminal 11 changes very little as shown in Fig. 6, and instead the inverter current (storage current) decreases as shown in Fig. 8. Conversely, when the current waveform at the first terminal 11 is reversed and the power is being transmitted, the inverter current waveform is also reversed and the inverter current increases by the amount of the load current.

[0032] Due to these effects, even if a nonlinear load such as a rectifier circuit or an inductance load and capacitance load such as a motor are connected to the second terminal 12 and there is waveform distortion or a current phase shift relative to the voltage, the current waveform at the first terminal 11 can be prevented from being disturbed by current supplementation from the inverter 20.

[0033] As described above, according to this embodiment, a method can be adopted in which the current at the first terminal 11 is controlled to a current command value regardless of load fluctuations, and load fluctuations are absorbed as current fluctuations in the inverter 20. According to this aspect, increases and decreases in the current at the second terminal 12 are compensated for by the storage battery 110 connected to the inverter 20, and the second terminal 12 and the first terminal 11 can be electrically separated while the current value of the first terminal 11 is maintained. This makes it possible to provide a microgrid (MG) function in which the storage battery 110 functions as a power reservoir. In other words, there is an advantage in that load fluctuations at consumers do not leak into the grid, making it easier to realize an MG that is always connected to the grid.

[0034] In an AC current negative feedback circuit, a certain time constant must be provided for the current response to ensure the stability of the synchronous voltage. Therefore, in a configuration in which the current flowing from the storage battery 110 is not controlled based on the detection result of the second current sensor 32, a response delay occurs to current changes within the negative feedback circuit. Due to this response delay, when a current fluctuation from the second terminal 12 is applied to the current negative feedback circuit, the circuit is unable to respond instantaneously, resulting in a corresponding fluctuation in the current value at the first terminal 11. In response to this problem, by controlling the current flowing from the storage battery 110 based on the detection result of the second current sensor 32 and compensating by positively feeding back the current value at the second terminal 12 to the power conversion circuit, such instantaneous fluctuations can be compensated for.

[0035] As shown in FIG. 9 , a blockchain 200 capable of communicating with multiple AC-DC power conversion devices 100 may be provided. The blockchain 200 may be configured to store information such as the amount of power, current value, and price actually supplied from one AC-DC power conversion device 100 to another. As an example, when one AC-DC power conversion device 100 actually supplies power to another AC-DC power conversion device 100, reservation information for the amount of power may be written in advance, and the actual amount of power supplied and the amount of power demanded and supplied may be written to the blockchain. FIG. 9 shows an example in which multiple AC-DC power conversion devices (GPI) 100 connected to storage batteries are connected to a power distribution system. The second terminal 12 of each AC-DC power conversion device 100 is connected to a consumer's load and is also connected to the blockchain on the Internet via a PC as an application (AP). According to the AC-DC power conversion device 100 of this embodiment, even if the load such as a household load changes instantaneously, the change can be quickly followed, and the current value at the first terminal 11 and the second terminal 12 can be maintained constant.

[0036] When a smart contract is established within the blockchain 200, the current transmission / reception start time and end time and current value included in the result of the contract are exchanged, and the AC / DC power conversion device 100 can start and end operation according to that time and current value. According to this embodiment, even if the load, such as a household load, changes instantaneously, the change can be quickly followed, and the accuracy of the current value exchanged between the AC / DC power conversion devices 100 can be improved.

[0037] An example of this flow is shown below. (a) Each consumer sends a power sale request and a power purchase request based on the amount of power stored in the storage battery 110 using a smart contract mechanism. (b) When a smart contract is concluded with AP1 selling power and AP3 receiving power in FIG. 9 , AP1 notifies AP3 of the start and end times. (c) AP1 starts the inverter 20 at the power interchange start time and transmits power at the specified current value. (d) AP3 starts the inverter 20 at the power interchange start time and receives power at the specified current value. (e) After the power interchange ends, AP1 writes the total transmitted power amount and AP3 writes the total received power amount to the blockchain 200. In a microgrid (MG) simultaneously connected to loads, PV generators, etc., providing an AC-DC power conversion device 100 capable of transmitting and receiving a specified amount of power for a specified period of time, as in this embodiment, enables advance purchase of power and facilitates power distribution management. This makes it possible to buy and sell power using smart contracts based on blockchain technology.

[0038] By adopting the AC-DC power conversion device 100 according to this embodiment, it is possible to prevent momentary deviations due to on / off of the load with respect to the current value transmitted in (c) above and the current value received in (d) above, which is beneficial in that it is possible to transmit and receive power with high accuracy. As a result, it is possible to prevent deviations of the actually used power, current, etc. written in the blockchain 200 from the reserved values.

[0039] A series of operation logs and a series of contract contents may be written to a block of the blockchain 200. Also, only the results of the agreed-upon contract contents may be written to a block of the blockchain 200, or the agreed-upon contract contents and the reasons for the agreement may be written to a block of the blockchain 200. As another example, the contract contents (plan contents) such as the electricity seller, electricity receiver, amount of electricity, price, and reason for the transaction may be written to a block of the blockchain 200. Furthermore, when electricity is actually sent, the actual contents (execution contents) such as the electricity seller, electricity receiver, and amount of electricity may be written to a block of the blockchain 200. Furthermore, the consideration for the electricity transaction may be used as a resource for circulation as local coins or points.

[0040] By using the blockchain 200, it is possible to prevent tampering and also make the contents of the contract and the actual content provided open to designated users.

[0041] Problems that arise when the embodiment described above is not adopted are described below. (A) A commonly used system combining a solar power generator, an inverter, and a storage battery switches between charging and discharging the storage battery independently, rather than charging the battery based on the difference between the received current and the consumed current, as in the present embodiment. Therefore, most of the load fluctuations depend on the grid break-in effect and the inertial force of the synchronous generator. Therefore, even if the utilization rate of the power company's synchronous generator drops, the inertial force cannot be reduced. (B) One possible method for absorbing load fluctuations and solar power generation fluctuations using an inverter and a storage battery is to temporarily store the generated power and then supply it to the load via an inverter. However, this requires two circuits, a storage circuit and an inverter circuit, which makes the control complex and expensive. (C) A power converter using a single inverter circuit may be an inverter that has both an AC power control terminal and a terminal that outputs from the power converter. However, since the power is calculated by averaging the product of the voltage and current values ​​over at least one cycle, the negative feedback current value is expected to be the average current value over several cycles, rather than the instantaneous current value. Therefore, there is a problem that the inverter cannot respond instantaneously to abrupt load fluctuations due to the voltage control terminal or disturbances due to fluctuations in the generator. In contrast, according to this embodiment, the above problems (A) to (C) can be solved.

[0042] The AC-DC power conversion device 100 of this embodiment can be used in a single-phase two-wire AC power distribution system, a single-phase three-wire AC power distribution system, a three-phase three-wire AC power distribution system, a three-phase four-wire AC power distribution system, and the like. While Figs. 1, 9, 10, and the like show the wiring collectively, as an example, the configurations shown in Fig. 11 are shown for a single-phase two-wire AC power distribution system, a single-phase three-wire AC power distribution system, and a three-phase three-wire AC power distribution system. In a single-phase two-wire AC power distribution system, two pairs of switching elements 130u, 130n, and 130v, each consisting of a pair of FETs or the like, shown in Fig. 11 are used. On the other hand, in a single-phase three-wire AC power distribution system and a three-phase three-wire AC power distribution system, all three pairs of switching elements 130u, 130n, and 130v shown in Fig. 11 are used.

[0043] In the embodiment shown in Figure 11, three sets of first current sensors 31u, 31n, 31v, three sets of second current sensors 32u, 32n, 32v, three sets of first wirings 41u, 41n, 41v, three sets of second wirings 42u, 42n, 42v, three sets of phase synchronization wirings 46u, 46n, 46v, three sets of first loop wirings 51u, 51n, 51v, three sets of second loop wirings 52u, 52n, 52v, and three sets of common wirings 45u, 45n, 45v are provided. That is, the first current sensor 31 has three sets of first current sensors 31u, 31n, and 31v, the second current sensor 32 has three sets of second current sensors 32u, 32n, and 32v, the first wiring 41 has three sets of first wirings 41u, 41n, and 41v, the second wiring 42 has three sets of second wirings 42u, 42n, and 42v, the phase synchronization wiring 46 has three sets of phase synchronization wirings 46u, 46n, and 46v, the first loop wiring 51 has three sets of first loop wirings 51u, 51n, and 51v, the second loop wiring 52 has three sets of second loop wirings 52u, 52n, and 52v, and the common wiring 45 has three sets of common wirings 45u, 45n, and 45v.

[0044] In a single-phase two-wire AC power distribution system, one wire is used as the "line" that supplies power, and the other is configured as the "neutral wire" or "ground wire." The wiring is simple and the installation costs are low, making it suitable for the small-scale power demands of an average household, and it is used for lighting, small home appliances, etc. In a single-phase two-wire AC power distribution system, a voltage of, for example, 100V is supplied to a load by connecting it to any two of the sub-distribution lines U2, N2, and V2.

[0045] A single-phase three-wire AC power distribution system consists of three wires. 200V is obtained between two phases (U-V phases) and 100V is obtained between each phase and the neutral wire (U-N phases, V-N phases). It has a high power supply capacity and can also handle large electrical appliances (air conditioners, heaters, etc.). It is used in ordinary households where 200V equipment is used, and in small commercial facilities. In a single-phase three-wire AC power distribution system, for example, by connecting a load to sub-distribution lines U2 and N2, or sub-distribution lines V2 and N2, a voltage of, for example, 100V is supplied to the load. On the other hand, by connecting a load to sub-distribution lines U2 and V2, a voltage of, for example, 200V is supplied to the load.

[0046] The three-phase, three-wire AC power distribution system also consists of three wires. The same voltage (200V or 400V) is used between each layer, and by using the three phases equally, power balance is maintained, making it efficient. Due to its high power supply capacity, it is used in factories and large facilities. While "single phase" consists of one waveform, "three phase" is a waveform made up of a combination of three "single phases," with each "single phase" shifted by 120 degrees.

[0047] The three-phase, four-wire AC power distribution system consists of three phase wires and one neutral wire (N), and can provide voltages such as 240V or 415V. It can supply both single-phase and three-phase loads simultaneously, and is used in large commercial facilities, factories, industrial facilities, etc.

[0048] In a single-phase three-wire AC distribution system, the current values ​​of the U2 phase and the V2 phase differ depending on the load connected to the sub-distribution line. However, by absorbing this current difference using the storage battery 110, the current value of the main distribution line can be controlled, and the current values ​​of the U1 phase and the V1 phase can be balanced while the current value of the N1 phase can be set to 0 A.

[0049] In the case of a three-phase three-wire AC power distribution system, three sets of switching elements are used, and the peak current values ​​of the U1 phase, V1 phase, and N1 phase can be balanced in the same way as in a single-phase three-wire AC power distribution system.

[0050] In the case of a three-phase four-wire AC power distribution system, four sets of switching elements are used, and the peak current values ​​of the U1 phase, V1 phase, and N1 phase can be balanced in the same way as in a single-phase three-wire AC power distribution system, while the current value of the N1 phase can be set to 0 A.

[0051] The above-mentioned description of each embodiment and the disclosure of the drawings are merely examples for explaining the invention described in the claims, and the above-mentioned description of the embodiment or the disclosure of the drawings does not limit the invention described in the claims.

[0052] REFERENCE SIGNS LIST 11 First terminal 12 Second terminal 13 Third terminal 20 Inverter 31 First current sensor 32 Second current sensor 41 First wiring 42 Second wiring 45 Common wiring 46 Phase synchronization wiring 51 First loop wiring 52 Second loop wiring 100 AC-DC power conversion device 110 Storage battery 200 Block chain

Claims

1. An AC-DC power conversion device comprising: a first terminal connected to a main distribution line; a second terminal connected to a sub-distribution line; a third terminal connected to a storage battery; an inverter provided between the third terminal and the first terminal and between the third terminal and the second terminal; a first current sensor provided between the inverter and the first terminal; and a second current sensor provided between the inverter and the second terminal, wherein the AC-DC power conversion device controls a current based on a detection result by the first current sensor, and controls a current based on a detection result by the second current sensor.

2. An AC-DC power conversion device according to the present invention comprises: a first terminal connected to a main distribution line; a second terminal connected to a sub-distribution line; a third terminal connected to a storage battery; an inverter having a current detector provided between the third terminal and the first terminal and between the third terminal and the second terminal; and a first current sensor provided between the inverter and the first terminal, wherein the AC-DC power conversion device controls current based on a detection result by the first current sensor, and controls current based on a difference between a current value detected by the current detector and a current value detected by the first current sensor.

3. The AC-DC power conversion device according to claim 1 or 2, wherein a first loop wiring connected to the inverter is provided in a first wiring provided between the inverter and the first terminal, and a negative feedback loop circuit is formed by the first wiring and wiring including the first loop wiring.

4. The AC-DC power conversion device according to claim 1 or 2, wherein a second loop wiring connected to the inverter is provided in a second wiring provided between the inverter and the second terminal, and a positive feedback loop circuit is formed by the second wiring and wiring including the second loop wiring.

5. An AC / DC power conversion device according to claim 1 or 2, wherein a control current signal is input to the inverter, and an AC instantaneous current value is calculated based on the control current signal to control the current at the first terminal.

6. The AC-DC power conversion device according to claim 1 or 2, wherein a first wiring provided between the inverter and the first terminal includes a phase synchronization wiring connected to the inverter, and a phase synchronization circuit is provided on the phase synchronization wiring.

7. An AC / DC power conversion device according to claim 1 or 2, wherein the main distribution line is connected to a power distribution system, and the sub-distribution line is connected to a consumer load or a generator.

8. The AC / DC power conversion device according to claim 1 or 2, which is used in a single-phase three-wire AC power distribution system, a three-phase three-wire AC power distribution system, or a three-phase four-wire AC power distribution system, and balances the relative current values ​​at the first terminals by controlling the current based on the detection result by the second current sensor, or by controlling the current based on the difference between the current value detected by the current detector and the current value detected by the first current sensor.

9. A power system comprising a plurality of AC / DC power conversion devices, each comprising the AC / DC power conversion device according to claim 1 or 2, wherein when power is actually transferred from one AC / DC power conversion device to another, reservation information for the amount of power is written in advance, and the actual amount of power supply and demand is written to the blockchain.

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