JP2013078231A - Current control system, current control device, and current control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current control system that reduces switching loss.SOLUTION: A current control system 100 includes a first electric apparatus 120 which outputs a first current to a power distribution network, a second electric apparatus 110 which outputs a second current to the power distribution network, and a current control device 200 which controls the first electric apparatus 120 and second electric apparatus 110. The first electric apparatus 120 serves as a current source which outputs the first current as a pulse-width modulated current to the power distribution network. The current control device 200 determines the currents output to the first electric apparatus 120 and second electric apparatus 110 respectively so that the first current has a rectangular waveform and the second current has a waveform obtained by subtracting the waveform of the first current from a predetermined current waveform, and reports a command value for outputting the determined currents to the first electric apparatus 120 and second electric apparatus 110.

Description

  The present invention relates to a current control system and the like. In particular, the present invention relates to a current control system that supplies current to a load device by controlling a current source.

  Conventionally, a power supply system in which a power generation device such as a solar power generation system or a fuel cell system is installed for each consumer has been developed. In such a system, when natural energy such as a photovoltaic power generation system is used for the power generation device, the amount of power generation varies depending on time and weather. In addition, there are variations in consumer power consumption during the day and at night. As a result, there may be excess or deficiency between the power supply from the power generation device and the power demand of the consumer.

  Therefore, a system in which a power storage device and a grid power network are connected to a power generator is used (for example, see Patent Document 1). In this case, the power storage device is used to store the power generated by the power generation device. And the electric power stored in the electrical storage apparatus is supplied to a consumer, when the electric power supply of an electric power generating device is insufficient with respect to the electric power demand of a consumer. Further, when there is a fluctuation in power demand exceeding the power storage capacity of the power storage device, the customer purchases power from the grid power network. The consumer can also sell the surplus power that has flowed backwards to the electric utility.

  Here, the power generator is connected to a one-way DC / AC inverter (so-called power conditioner) for converting the direct current output from the power generator into an alternating current having a predetermined characteristic. Specifically, the predetermined characteristic is determined by a harmonic suppression countermeasure guideline (see Non-Patent Document 1). According to this guideline, the power conditioner connected to the power generator must suppress the outflow of harmonic current from the customer side to the grid power network to 5% or less.

  In order to realize this, the power conditioner performs instantaneous current control. Therefore, the power conditioner linked to the grid power network operates as a current source that outputs a sine wave. The power storage device is connected to a bidirectional DC / AC inverter. That is, the power storage device and the unidirectional DC / AC inverter connected thereto operate as a voltage source for the current source.

Japanese Unexamined Patent Publication No. Sho 63-110922

“Guidelines for Harmonic Suppression for Consumers Receiving High Voltage or Extra High Voltage” [online], established in January 2004, NISA, [searched on August 15, 2009], Internet <URL: http://www.nisa.meti.go.jp/oshirase/2004/files/160131oshirase.pdf>, p. 7

  However, according to the prior art, there is a problem that the switching loss in the power conditioner is large.

  That is, as described above, the power conditioner converts the direct current supplied from the power generation device into an alternating current having a sine waveform and outputs the alternating current. In the prior art, pulse width modulation and pulse amplitude modulation are known as control methods used by the power conditioner. For example, a DC voltage is converted into an AC voltage by applying an LC filter to the voltage pulse subjected to pulse width modulation. In order to output a sine wave that satisfies the above-mentioned harmonic suppression guideline, the power conditioner in the prior art performs pulse control at a high switching frequency of about 10 kHz, for example.

  However, the higher the switching frequency, the greater the power loss. This is because power loss occurs during the transition every time the switching element is switched ON / OFF. Hereinafter, this power loss is referred to as switching loss. This is because the switching loss increases as the switching frequency increases. Therefore, in the prior art, there is a problem that the switching loss is large in the power conditioner.

  Accordingly, an object of the present invention is to provide a current control system that reduces switching loss.

  One aspect of the current control system according to the present invention includes a first electric device that outputs a first current to a power distribution network to which a load device is connected, and a second electric device that outputs a second current to the power distribution network; A current control system that supplies a current to the load device by controlling the first electric device and the second electric device, wherein the first electric device Is a current source that outputs the first current, which is a current obtained by subjecting the supplied direct current to pulse width modulation, to the distribution network, and the current control device is output from the first electrical device. The waveform of the first current is a rectangular wave, and the waveform of the second current output from the second electrical device is a waveform obtained by subtracting the waveform of the first current from a predetermined current waveform. The first electric device and the second electric device A determination unit that determines a current to be output to each of the devices, and a command value for causing the first electric device to output the determined first current is notified to the first electric device; A notification unit that notifies the second electric device of a command value for causing the second electric device to output the second current.

  According to this configuration, since the first electric device only needs to output a rectangular wave having the same frequency as the commercial power supply frequency, for example, the switching frequency when the supplied current is subjected to pulse control is significantly lower than the conventional one. can do. As a result, power loss due to switching can be greatly reduced. In addition, an LC filter that has been conventionally required for outputting a sine wave is not necessary, so that the circuit configuration of the first electric device can be simplified.

  The present invention can be realized not only as such a current control system but also as a current control method using characteristic means included in the current control system as steps, or executing such characteristic steps in a computer. It can also be realized as a program to be executed. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM (Compact Disc Read Only Memory) and a transmission medium such as the Internet.

  Furthermore, the present invention can be realized as a semiconductor integrated circuit (LSI) that realizes part or all of the functions of such a current control system, or can be realized as a current control device included in such a current control system. .

  As mentioned above, according to this invention, the current control system which reduces switching loss can be provided.

It is a figure which shows the structure of the current control system which concerns on the related technique of this invention. It is a figure which shows an example of the circuit structure of the voltage source with which the current control system shown by FIG. 1 is equipped, and a current source. In the related art of this invention, it is a conceptual diagram which shows the voltage source and electric current source which supply electric power to a load apparatus. _{I LOAD, i LOAD1} shown in Figure _3A, and _{i LOAD2} a diagram of a waveform having the. Shown in FIG. _3A, a diagram of a waveform having the _{i FC} and _{i SB.} It is a figure which shows the structure of the current control system which concerns on Embodiment 1 of this invention which operate | moves in self-sustained operation mode. It is a figure which shows an example of the circuit structure of the creation cooperation PC which the current control system shown by FIG. 4 has. It is a figure which shows the functional block of a current control apparatus. 5 is a flowchart showing a flow of overall processing performed by the current control device according to Embodiments 1 and 2 in the self-sustaining operation mode. 3 is a diagram illustrating an example of a functional block of a calculation unit included in the current control device according to Embodiments 1 and 2. FIG. 3 is a flowchart illustrating a flow of processing performed by a calculation unit included in the current control device according to the first and second embodiments. It is a flowchart which shows an example of the process in which a determination part notifies the command value of an electric current, when FC does not have the capability to change output electric power. It is a flowchart which shows an example of the process in which a determination part determines an electric current command value, when FC has the capability to change output electric power. In the current control system concerning Embodiment 1, it is a key map showing current supplied to a load device. It is a figure explaining the waveform of each current shown by FIG. It is a figure which shows the functional block of the current control system in Embodiment 2 of this invention. In the current control system concerning Embodiment 2, it is a key map showing the current supplied to a load device. FIG. 16 is a diagram illustrating waveforms of a first current, a second current, and a third current shown in FIG. It is a figure which shows the functional block of the current control system which concerns on Embodiment 1 of this invention which operate | moves in grid connection mode. It is a figure which shows the input / output of the current control apparatus which concerns on Embodiment 1 and 2. It is a conceptual diagram showing the mode switching process which the current control apparatus which concerns on Embodiment 1 and 2 performs. 3 is a diagram illustrating an example of functional blocks of a calculation unit according to Embodiment 1. FIG. It is a flowchart which shows the flow of the process which the current control apparatus which concerns on Embodiment 1 performs in grid connection mode. It is a conceptual diagram which shows SB and FC which supply electric power to a load apparatus in a grid connection mode. It is a figure for demonstrating the waveform of the electric current output from SB and FC in a grid connection mode. It is a block diagram which shows the hardware constitutions of the computer system which implement | achieves the current control apparatus etc. concerning Embodiment 1 and 2 of this invention.

  One aspect of the current control system according to the present invention includes a first electric device that outputs a first current to a power distribution network to which a load device is connected, and a second electric device that outputs a second current to the power distribution network; A current control system that supplies a current to the load device by controlling the first electric device and the second electric device, wherein the first electric device Is a current source that outputs the first current, which is a current obtained by subjecting the supplied direct current to pulse width modulation, to the distribution network, and the current control device is output from the first electrical device. The waveform of the first current is a rectangular wave, and the waveform of the second current output from the second electrical device is a waveform obtained by subtracting the waveform of the first current from a predetermined current waveform. The first electric device and the second electric device A determination unit that determines a current to be output to each of the devices, and a command value for causing the first electric device to output the determined first current is notified to the first electric device; A notification unit that notifies the second electric device of a command value for causing the second electric device to output the second current.

  According to this configuration, the first electric device can significantly reduce the switching frequency when performing pulse control on the supplied current as compared with the conventional one. As a result, power loss due to switching can be greatly reduced. In addition, an LC filter that has been conventionally required for outputting a sine wave is not necessary, so that the circuit configuration of the first electric device can be simplified.

  Specifically, each of the first electric device and the second electric device has a switching element for converting the waveform of the supplied current, and the switching that the first electric device has. The switching frequency, which is the switching frequency of the element, may be 100 Hz or 120 Hz, and the switching frequency of the switching element included in the second electric device may be 1 kHz to 100 kHz or less.

  According to this, the 1st electric equipment should just output the rectangular wave of the same frequency as commercial power supply frequency, for example. Therefore, the switching frequency can be greatly reduced. As a result, power loss due to switching can be reduced.

  The current control system is a mode changeover switch for switching between a grid connection mode in which the current control system operates in conjunction with a power system and a self-sustained operation mode in which the current control system operates by being disconnected from the power system. The current control device further includes an acquisition unit that acquires information related to a load current that is a current supplied to the load device, and in the self-sustained operation mode, the current control device includes the second electric device. The determination unit determines the second current to be a waveform obtained by subtracting the waveform of the first current from the waveform of the load current that is the predetermined current waveform, and the system In the interconnection mode, the current control device controls the second electric device as a current source, and the determination unit determines the second current as the predetermined current waveform. May be determined so that a waveform obtained by subtracting the waveform of the first current from a sine wave.

  According to this, the current control system can be controlled so that an appropriate current is supplied to the load according to each of the case where the current control system is connected to the grid and the case where the current control system operates independently from the grid.

  In addition, the current control system further switches between a grid connection mode in which the current control system operates in conjunction with a power system and a self-sustained operation mode in which the current control system operates by being disconnected from the power system. A changeover switch and a third electric device that is a current source that outputs a third current different from the first current and the second current, and the current control device is a current supplied to the load device. An acquisition unit that acquires information about a certain load current; in the self-sustained operation mode, the current control device controls the second electric device as a voltage source; and the determination unit determines the second current, A waveform obtained by subtracting the waveforms of the first current and the third current from the waveform of the load current which is a predetermined current waveform, and in the grid connection mode, The control device controls the second electric device as a current source, and the determination unit converts the second current from the sine waveform that is the predetermined current waveform to the waveforms of the first current and the third current. It may be determined so as to obtain a subtracted waveform.

  According to this, even when the current control system includes a plurality of power generators, the power output from each power generator can be supplied to the load more efficiently. Further, since the LC filter is not required in the current source connected to each power generation device, it is possible to realize cost saving and space saving of the device.

  Further, the determination unit further includes, in the self-sustained operation mode, the waveform of the first current so that a waveform obtained by adding the waveform of the first current and the waveform of the third current approximates the waveform of the load current. The waveform is determined, and in the grid connection mode, the waveform of the first current is determined so that a waveform obtained by adding the waveform of the first current and the waveform of the third current approximates the sine waveform. Also good.

  According to this, a current waveform obtained by synthesizing currents output from a plurality of current sources approximates a current waveform to be finally generated. Accordingly, when the current to be finally generated is generated by further combining the second current with the current obtained by combining the currents output from the plurality of current sources, the time change of the second current to be output is changed. It can be suppressed. As a result, for example, when the second current is output from the storage battery, deterioration of the storage battery can be suppressed.

  One aspect of the current control device according to the present invention includes: a first electric device that outputs a first current to a power distribution network to which a load device is connected; and a second electric device that outputs a second current to the power distribution network; The first electrical device is a current source that outputs the first current, which is a current obtained by subjecting the supplied direct current to pulse width modulation, to the distribution network. The waveform of the first current output from the first electrical device is a rectangular wave, and the waveform of the second current output from the second electrical device is changed from the predetermined current waveform to the first current. A determination unit that determines a current to be output to each of the first electric device and the second electric device so as to obtain a waveform obtained by subtracting the waveform, and the determined first current to the first electric device The command value for output is passed to the first electrical device. And comprises an instruction value for outputting the determined second current to said second electrical device, and a notification unit for notifying to the second electrical device.

  One aspect of the current control method according to the present invention includes: a first electric device that outputs a first current to a power distribution network to which a load device is connected; and a second electric device that outputs a second current to the power distribution network; A current source that outputs the first current, which is a current obtained by subjecting the supplied direct current to pulse width modulation, to the distribution network. The waveform of the first current output from the first electrical device is a rectangular wave, and the waveform of the second current output from the second electrical device is the first current from the predetermined current waveform. A determination step for determining a current to be output to each of the first electric device and the second electric device so as to obtain a waveform obtained by subtracting a waveform of a current, and the determined first current to the first electric device The command value for causing the device to output the first value Notify the care device, the command value for outputting the determined second current to said second electrical device, and a notification step of notifying to the second electrical device.

  Hereinafter, in order to clarify the problem and effect which this invention solves first, with reference to FIGS. 1-3C, the current control system which concerns on the related technique of this invention is demonstrated.

  FIG. 1 shows a configuration of a current control system 900 according to the related art. FIG. 2 shows an example of the circuit configuration of the voltage source 910 and the current source 920 included in the current control system 900 shown in FIG.

  As shown in FIG. 1, the current control system 900 supplies current supplied from an SB (Secondary Battery) 919 and an FC (Fuel Cell) 929 to a load 950A and a load 950B. Control. Further, the current control system 900 is also connected to the system 890. More specifically, the current control system 900 includes a voltage source 910, a current source 920, and a current controller 930.

The voltage source 910 outputs a nonlinear current i _SB based on the power supplied from the _SB 919. The current source 920 outputs a sine wave current i _FC based on the power supplied from the _FC 929. Here, the non-linear current is a current having a non-linear (that is, not a sine wave) waveform. The sine wave current is a current whose waveform has a sine wave shape.

The voltage source 910 transforms the direct current supplied from the SB 919 by the bidirectional DC / DC converter 911 that performs bidirectional DC / DC charge / discharge control. Further, the bidirectional voltage source inverter 912 performs pulse control on the transformed voltage. The pulse signal thus obtained is subjected to processing by the LC filter 913, thereby generating a desired nonlinear current _iSB .

The current source 920 transforms the direct current supplied from the FC 929 by the one-way DC / DC converter 921 that performs one-way DC / DC discharge control. Further, the one-way voltage source inverter 922 performs pulse control on the transformed voltage. The pulse signal thus obtained is processed by the LC filter 923 to generate a desired sine wave current i _FC .

  In order to generate a nonlinear current and a sine wave current, it is necessary to perform pulse control at a high switching frequency.

  Here, using a higher switching frequency in the voltage source 910 and the current source 920 further increases power loss due to switching. Hereinafter, power loss due to switching is referred to as switching loss. Since the switching loss increases as the switching frequency is higher, it is not preferable to use a very high switching frequency.

  However, the current control system 900 is connected to the grid 890. Thus, for example, in order to follow the harmonic suppression countermeasure guidelines, it is necessary to suppress the outflow of the harmonic current from the customer side to the grid power network to 5% or less. For this reason, the voltage source 910 and the current source 920 need to use a high switching frequency of, for example, 10 kHz or more and perform fine control of the output current waveform.

  Next, current waveforms output from the voltage source 910 and the current source 920 will be described in more detail with reference to FIGS. 3A to 3C.

  FIG. 3A is a conceptual diagram showing a voltage source 910 and a current source 920 that supply power to a load device in the related art of the present invention.

As shown in FIG. 3A, the voltage source 910 outputs a current i _SB and a voltage V _PCS . The current source 920 outputs a current i _FC .

The current output from the voltage source 910 and the current source 920 is supplied to the load device as i _LOAD . More specifically, i _LOAD1 is supplied to a load 950A that is a resistive load. Also, i _LOAD2 is supplied to a load 950B that is a rectifier load.

FIG. 3B shows waveforms that i _LOAD, i _LOAD1, and i _LOAD2 shown in FIG. 3A have. The vertical axis indicates the current magnitude [A], and the horizontal axis indicates the elapsed time [s].

As shown in FIG. 3B, the current i _LOAD2 supplied to the load 950B, which is a rectifier load, has a non-linear shape. As a result, the current i _LOAD supplied to the loads 950A and 950B also has a non-linear shape.

FIG. 3C shows waveforms of i _FC and i _SB shown in FIG. 3A. The vertical axis indicates the current magnitude [A], and the horizontal axis indicates the elapsed time [s].

As shown in FIG. 3C, the current i _FC output from the current source 920 according to the related art has a sine wave shape. On the other hand, the current i _SB output from the voltage source 910 has a non-linear shape.

As described above, in the current control system 900 according to the related art, the current source 920 is controlled to output a sine wave current as the current i _FC . As a result, a large switching loss occurs in the inverter.

  In the current control system according to the present invention described below, the switching loss can be reduced by solving this problem.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are examples. Therefore, the present invention is not limited by these embodiments. The invention is limited only by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are not necessarily required to achieve the object of the present invention. It will be described as constituting a preferred form.

(Embodiment 1)
First, with reference to FIG.4 and FIG.5, the structure of the current control system which concerns on embodiment of this invention is demonstrated.

  FIG. 4 shows a configuration of current control system 100 according to Embodiment 1 of the present invention. FIG. 5 shows an example of a circuit configuration of the creation cooperation PCS 202 included in the current control system 100 shown in FIG.

As shown in FIG. 4, the current control system 100 outputs the first electric current i _FC to the distribution network 880 to which the load 150 </ b> A that is a resistive load and the load 150 </ b> B that is a rectifier load are connected. Including device 120; In addition, it includes a second electrical device 110 that outputs i _SB as a second current to the power distribution network 880. Moreover, the current control apparatus 200 which supplies an electric current with respect to the load 150A and the load 150B by controlling the 1st electric equipment 120 and the 2nd electric equipment 110 is included. Here, the first electrical device 120 is a current source that outputs to the distribution network 880 a first current that is a current obtained by subjecting a direct current supplied from the FC to pulse width modulation. Therefore, the first electric device 120 is also referred to as a current source or a current source.

Hereinafter, the load 150A is also referred to as a first load device, and the load 150B is also referred to as a second load device. The current i _FC is also referred to as a first current, and the current i _SB is also referred to as a second current.

  Further, unless otherwise specified in the following description, as shown in FIG. 4, it is assumed that the current control system 100 operates separately from the system. In this case, the second electric device 110 operates as a voltage source. Therefore, the second electric device 110 is also called a voltage source.

The voltage source 110 outputs a current i _SB having a non-linear waveform. The i _SB cycle is preferably matched with the load 150A and the load 150B. For example, if the commercial power supply frequency is 60 Hz, the i _SB cycle is also 60 Hz.

  The voltage source 110 includes a bidirectional DC / DC converter 111, a bidirectional voltage source inverter 112, an LC filter 113, and a second control unit 114.

  The bidirectional DC / DC converter 111 is a converter between DC voltages. The bidirectional DC / DC converter 111 converts a voltage when the SB 119 is discharged or charged to the SB 119.

  The bidirectional voltage source inverter 112 performs pulse control on the voltage output from the bidirectional DC / DC converter 111 in order to convert a direct current into an alternating current when the SB 119 is discharged. Specifically, it is conceivable to perform pulse width modulation or pulse amplitude modulation on the voltage. Note that the switching frequency of the pulse control performed by the bidirectional voltage source inverter 112 is, for example, 10 kHz.

  The LC filter 113 converts the pulse voltage output from the bidirectional voltage source inverter 112 into a sine waveform.

  The second control unit 114 controls the bidirectional DC / DC converter 111 and the bidirectional voltage source inverter 112 according to the SB current command value that is the command value acquired from the current control device 200. Specifically, the current according to the command value is discharged to SB119 or charged to SB119.

The current source 120 outputs a current i _FC having a sinusoidal waveform. When the commercial power supply frequency is 60 Hz, the i _FC cycle is 60 Hz, similar to i _SB . The current source 120 includes a one-way DC / DC converter 121, a one-way current source inverter 122, and a first control unit 124. The current source 120 does not have an LC filter.

  The one-way DC / DC converter 121 is a converter between DC voltages. The one-way DC / DC converter 121 converts the voltage of the current supplied from the FC 129.

  The unidirectional current source inverter 122 performs pulse width modulation on the current output from the unidirectional DC / DC converter 121. Note that the switching frequency of the pulse width modulation performed by the unidirectional current source inverter 122 may be 120 Hz, for example, when the commercial power supply frequency is 60 Hz. This is for generating a pulse waveform having one peak and one valley in one period.

  That is, each of the first electric device 120 and the second electric device 110 includes a switching element for converting the waveform of the supplied current. Here, the switching frequency, which is the switching frequency of the switching elements included in the first electric device 120, is twice the commercial power supply frequency. Specifically, in Japan, it is 100 Hz or 120 Hz. The switching frequency of the switching element included in the second electric device is 1 kHz to 100 kHz or less.

  The first electric device 120 and the second electric device 110 are collectively referred to as a creation cooperation PCS (Power Conditioner).

  The current control device 200 determines a control method for the voltage source 110 and the current source 120 based on the main information acquired from the mode switch. Details of the current control device 200 will be described later.

  Furthermore, the current control system 100 includes a mode change switch 204 and a current sensor 870.

  The mode switch 204 is a switching device that switches the connection state between the current control system 100 and the system 890 to either ON or OFF. A state where the current control system 100 and the system 890 are connected by the mode switch 204 is referred to as a system interconnection mode. A state in which current control system 100 and system 890 are disconnected is referred to as a self-sustained operation mode. That is, the mode changeover switch 204 switches between a grid connection mode in which the current control system 100 operates in conjunction with the power system and a self-sustained operation mode in which the current control system 100 operates by being disconnected from the power system. As described above, when the current control system 100 is in the self-sustaining operation mode, the second electric device 110 operates as a voltage source. On the other hand, when the current control system 100 is in the grid connection mode, the grid 890 becomes a voltage source. Therefore, the second electrical device 110 may operate as a current source.

The current sensor 870 is a current sensor that measures the current supplied to the load 150A and the load 150B. The current sensor 870 is attached to, for example, a customer distribution network 880. The current sensor 870 outputs the measured current value to the current control device 200 via a wired or wireless communication network. Note that the current sensor may not be installed at the position indicated as the current sensor 870. In other words, it can be installed at any location as long as it can acquire the i _LOAD value.

  The FC 129 that outputs power to the current source 120 is an arbitrary type of fuel cell such as a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, or a solid oxide fuel cell. Can be used. The SB 119 that charges or discharges power with the voltage source 110 is an arbitrary type of storage battery such as a lithium ion battery, a lead storage battery, a sodium / sulfur battery, or a nickel cadmium battery.

  Next, FIG. 6 shows functional blocks of the current control device 200.

  As illustrated in FIG. 6, the current control device 200 includes an acquisition unit 210, a calculation unit 212, a determination unit 214, and a notification unit 216.

The acquisition unit 210 acquires information on a load current i _LOAD that is a current supplied to the load 150A and the load 150B from the current sensor 870. Specifically, at least one of the amplitude, phase, and frequency of the load current i _LOAD is acquired.

The calculation unit 212 performs calculation processing for determining the first current i _FC that the current source 120 should output to the power distribution network 880. Details will be described later.

The determination unit 214 determines the first current i _FC to be output from the first electric device 120 and the second current i _SB to be output from the second electric device 110.

More specifically, the determination unit 214 determines the waveform of the first current i _FC output from the first electric device 120 to be a rectangular wave. Further, the waveform of the second current i _SB output from the second electric device 110 is determined to be a waveform obtained by subtracting the waveform of the first current i _FC from the predetermined current waveform. Here, the predetermined current waveform is determined according to the operation mode of the current control system 100 selected by the mode switch 204.

  That is, in the self-sustaining operation mode, the current control device 200 controls the second electric device 110 as a voltage source. Further, the determination unit 214 determines the second current to be a waveform obtained by subtracting the waveform of the first current from the waveform of the load current that is a predetermined current waveform.

  On the other hand, in the grid connection mode, the current control device 200 controls the second electric device 110 as a current source. The determination unit 214 determines the second current to be a waveform obtained by subtracting the waveform of the first current from the sine waveform that is a predetermined current waveform. More details will be described later.

The notification unit 216 notifies the first electrical device 120 of a command value for causing the first electrical device 120 to output the first current i _FC determined by the determination unit 214. More specifically, the notification is sent to the first control unit 124 included in the first electric device 120. In addition, a command value for causing the second electric device 110 to output the second current i _SB is notified to the second electric device 110. More specifically, the second control unit 114 included in the second electric device 110 is notified.

As described above, the process of determining the first current i _FC and the second current i _SB by the determination unit 214 depends on whether the current control system 100 is operating in the self-sustaining operation mode or the grid connection mode. It depends on what you do.

  Therefore, first, the description will be made on the assumption that the current control system 100 is operating in the self-sustaining operation mode.

  FIG. 7 is a flowchart showing an overall processing flow performed by the current control device 200 according to the present embodiment in the self-sustaining operation mode.

  First, the acquisition unit 210 acquires a load current value. Further, the calculation unit 212 performs a calculation for calculating a waveform parameter necessary for determining the waveform of the first current. Furthermore, the determination unit 214 determines the waveform of the first current using the output of the calculation unit 212 (S100).

  Next, the determination unit 214 determines the waveform of the second current based on the waveform of the first current and the value of the load current (S200).

  Thereafter, the notification unit 216 notifies the second control unit 114 and the first control unit 124 of the current command value so as to output the current having the waveform determined by the determination unit 214 (S300).

  FIG. 8 shows functional blocks of the arithmetic unit 212 provided in the current control apparatus 200 according to the present embodiment.

  As shown in FIG. 8, the calculation unit 212 includes a rise time detection unit 302, a current on time calculation unit 304, and a current amplitude calculation unit 306.

The rise time detector 302 detects the rise time and fall time of the load current i _LOAD . Since rising and falling are in a relationship in which the polarity of the current is reversed, only the rising will be described as an example.

  The rise time detection unit 302 acquires the voltage phase information of the load current from the acquisition unit 210 and acquires the time when the voltage phase becomes zero. The time from this time to the time when the value of the load current becomes equal to or greater than a predetermined threshold is detected as the rise time of the load current.

Current on-time computing unit 304, unidirectional current source inverter _122, calculates the to time to the _{i FC} on. Details thereof will be described later.

Current amplitude calculation section 306 calculates the amplitude of the magnitude of the i _FC is a rectangular wave. Details thereof will be described later.

  Based on the parameters thus obtained by the calculation unit 212, the determination unit 214 determines a current command value to be notified to the current source 120.

  Further, the determination unit 214 determines the waveform of the second current so as to obtain a waveform obtained by subtracting the waveform of the first current from the waveform of the load current. Further, the current command value to be notified to the voltage source 110 is determined so that the voltage source 110 outputs the second current having the determined waveform.

  FIG. 9 is a flowchart showing a flow of processing performed by the arithmetic unit 212 included in the current control device 200 according to the present embodiment.

  First, the magnitude and phase of the load current are acquired from the acquisition unit 210 (S210).

Next, the rise time detection unit 302 detects the rise time of the load current (S212). Further, the current on time calculation unit 304 obtains the time for which i _FC should be turned on.

  Finally, the current amplitude calculator 306 obtains the magnitude of the first current amplitude. Thereby, all the information for determining the waveforms of the first current and the second current is obtained (S213).

  The current command value actually output from the current control device 200 to the voltage source 110 and the current source 120 includes more detailed control information depending on whether the FC 129 has the ability to change the output power. May be. This will be described with reference to FIGS.

  FIG. 10 is a flowchart illustrating an example of processing in which the determination unit 214 notifies the current command value when the FC 129 does not have the ability to change the output power.

  First, the determination unit 214 determines whether or not the load current is smaller than the rated current of the FC 129 (S230). Here, when it is determined that the load current is smaller than the rated current of the FC 129 (Yes in S230), the determination unit 214 notifies the second control unit 114 of a command value so that the change amount of the load current is supplied to the SB 119. (S232). Further, the command value is notified to the second control unit 114 so that the SB 119 is charged with the surplus of the output power of the FC 129 (S234).

  On the other hand, when it is determined that the load current is equal to or greater than the rated current of FC129 (No in S230), the determination unit 214 notifies the second control unit 114 of a command value so that the change amount of the load current is supplied to the SB119 ( S236). Further, the command value is notified so that the shortage of the power to be output by the FC 129 is supplied from the SB 119 (S238).

  In this way, by using the SB 119 as a buffer, the FC 129 having a constant output power can be used even when the load changes.

  FIG. 11 is a flowchart illustrating an example of processing in which the determination unit 214 determines the current command value when the FC 129 has the ability to change the output power.

  When the determination unit 214 determines that the load current is smaller than the rated current of the FC 129 (Yes in S230), the determination unit 214 notifies the second control unit 114 of a command value so that the change amount of the load current is supplied from the SB 119 (S232). ). Further, the command value is notified to the first control unit 124 so that the output of the FC 129 reaches the FC current command value at an arbitrary time constant (S235).

  On the other hand, when the determination unit 214 determines that the load current is equal to or greater than the rated current of the FC 129 (No in S230), the determination unit 214 notifies the second control unit 114 of a command value so that the change amount of the load current is supplied from the SB 119. (S236). Further, the command value is notified to the first control unit 124 so that the output of the FC 129 reaches the FC current command value at an arbitrary time constant (S237). Furthermore, the command value is notified to the second control unit 114 so that the power insufficient from the output of the FC 129 is supplied from the SB 119 (S238).

  The waveform of the current thus controlled by the current control device 200 will be described with reference to FIGS.

  FIG. 12 is a conceptual diagram showing the current supplied to the load device in the current control system 100 according to the present embodiment.

As shown in FIG. 12, the voltage source 110 outputs a current i _SB and a voltage V _PCS . The current source 120 outputs a current i _FC .

The current output from the voltage source 110 and the current source 120 is supplied to the load device as i _LOAD . More specifically, i _LOAD1 is supplied to the load 150A which is a resistive load. Further, i _LOAD2 is supplied to the load 150B which is a rectifier load.

FIG. 13 is a diagram for explaining the waveform of each current shown in FIG. More specifically, FIG. 13A shows waveforms of i _LOAD , i _LOAD1 , i _LOAD2 , and V _PCS . FIG. 13B shows the rise detection time and the fall detection time by the rise time detection unit 302. FIG. 13C shows the i _FC and i _SB waveforms determined by the current control device 200.

For example, the rise time detection unit 302 detects a time when the value of i _LOAD is equal to or greater than a predetermined threshold (this is set as t ₁ ). Thereafter, i _{FC is set} to 0 during the time T _OFF from the reference time t ₀ to t ₁ .

Then, the frequency of the alternating current to be supplied to the load (e.g., 60 Hz) when the reference frequency _{T B} and from time _{t 1,} during the time _{T ON = T B / 2-2t 1} , to ON _{i FC} . Here, turning on i _FC means changing the value of i _FC from Low to High. Specific value of i _FC when the ON is determined by the following equation as the maximum amplitude of the square wave (1).

Note that I _Rated is the rated current of FC129. In _{addition, P Rated} is the rated power of the FC129.

_Thereafter, a value between _{I FC} of _{T OFF} Low (e.g., 0). In this way, the waveform of a half period (mountain) of the rectangular wave is determined. Thereafter, the waveform of the valley of the rectangular wave can be determined by reversing the amplitude.

Rising time of the thus I _FC, fall time, and by determining the amplitude, waveform I _FC is a rectangular wave can be determined.

On the other hand, the i _SB waveform can also be determined by subtracting the value of I _FC thus determined from i _LOAD .

  As described above, according to the current control system 100 according to the present embodiment, since the current source 120 only needs to output a rectangular wave, the switching frequency when performing pulse width modulation on the supplied current is It can be made much lower than before. As a result, power loss due to switching can be greatly reduced. In addition, since the LC filter that is conventionally required for outputting a sine wave is not required in the current source 120, the circuit configuration of the current source 120 can be simplified.

(Embodiment 2)
Next, a current control system in the case where PV (Photovoltaics) is used together with FC129 as a current source will be described.

  FIG. 14 shows functional blocks of the current control system 100A in the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the component which is common in the current control system 100 shown in FIG. 4, and detailed description is abbreviate | omitted.

  As illustrated in FIG. 14, the current control system 100 </ b> A newly includes a PV 139 that is a solar power generation device and a third electric device 130 that receives power supply from the PV 139.

  Similar to the first electric device 120, the third electric device 130 is controlled as a current source that outputs a current obtained by subjecting the current to pulse width modulation. Therefore, the third electrical device 130 is also referred to as a current source or a current source. Further, as shown in FIG. 14, the description of the present embodiment also assumes that the current control system is disconnected from the system unless otherwise specified. Therefore, the second electric device 110 is also referred to as a voltage source.

  The current source 130 includes a unidirectional DC / DC converter 131, a unidirectional current source inverter 132, and a first control unit 134. The current source 130 does not have an LC filter.

  The one-way DC / DC converter 131 is a converter between DC voltages. The one-way DC / DC converter 131 converts the voltage of the current supplied from the PV 139.

  The unidirectional current source inverter 132 performs pulse width modulation on the current output from the unidirectional DC / DC converter 131. Note that the switching frequency of the pulse width modulation performed by the one-way current source inverter 132 is 120 Hz when the commercial power supply frequency is 60 Hz, for example, as in the current source 120. This is for generating a pulse waveform having one peak and one valley in one period.

That is, referring to FIG. 15, in current control system 100A, i _SB output from second electric device 110, i _FC output from first electric device 120, and output from third electric device 130 are output. current plus the _{i PV} that is, the load current _{i lOAD.}

Determining section current control device 200A of the current control system 100A according to the present embodiment comprises has (not shown), the second current _{i SB} the first current from the waveform of the load current _{i LOAD} is a predetermined current waveform i _The waveform is determined by subtracting the waveform of _FC and the third current i _PV . Hereinafter, the waveform of the current determined by the current control device 200A will be described more specifically with reference to FIG.

FIG. 16 is a diagram illustrating waveforms of the first current, the second current, and the third current shown in FIG. More specifically, FIG. 16A shows waveforms of i _LOAD , i _LOAD1 , i _LOAD2 , and V _PCS . Moreover, (b) of FIG. 16 shows the rising detection time and the falling detection time by the rising time detection unit (not shown) of the current control device 200A. Moreover, (c) of FIG. 16 shows the waveforms of i _FC , i _PV, and i _SB determined by the current control device 200A.

Referring to (a) to (c) of FIG. 16, the time when i _FC is turned on and the time when i _FC is turned off can be determined in the same manner as in current control device 200 according to the first embodiment, for example. That is, the current control device _200A, the _{time i LAOD} is greater than or equal _to the _threshold, turns ON the current value of _{i FC.} Further, it is turned off at other times. On the other hand, the period of the square wave i _PV is the value determined in advance. _{Specifically,} when the sum of the waveform of _{i FC} waveform and _{i PV,} so as to approximate to the load current _{i LOAD,} it is preferable to determine the period of the square wave _{i PV.} By burden SB119 which must output a nonlinear current _{i SB} is reduced, because that can suppress the deterioration of SB119.

  As described above, the current control system 100A according to the present embodiment includes the third electrical device 130 that outputs the third current different from the first current and the second current.

  In the self-sustained operation mode, the current control device 200A controls the second electric device 110 as a voltage source, and the determination unit included in the current control device 200A converts the second current into a load current having a predetermined current waveform. The waveform is determined by subtracting the waveforms of the first current and the third current from the waveform.

  In the grid connection mode, the current control device 200A controls the second electric device 110 as a current source, and the determination unit included in the current control device 200A converts the second current into a sine having a predetermined current waveform. It can be considered that the waveform is determined by subtracting the waveforms of the first current and the third current from the waveform.

  According to this, even when the current control system 100A includes a plurality of power generation devices, the power output from each power generation device can be supplied to the load more efficiently. In addition, since an LC filter is not required in the current source to which power is supplied from each power generation device, it is possible to reduce the cost and space of the device.

  In the self-sustained operation mode, it is preferable that the waveform of the first current is determined so that a waveform obtained by adding the waveform of the first current and the waveform of the third current approximates the waveform of the load current.

  In the grid connection mode, it is preferable to determine the waveform of the first current so that the waveform obtained by adding the waveform of the first current and the waveform of the third current approximates a sine waveform.

  According to this, a current waveform obtained by synthesizing currents output from a plurality of current sources approximates a current waveform to be finally generated. Accordingly, when the current to be finally generated is generated by further combining the second current with the current obtained by combining the currents output from the plurality of current sources, the time change of the second current to be output is changed. It can be suppressed. As a result, deterioration of SB119 that outputs the second current can be suppressed.

  In the description of the current control system according to the first and second embodiments of the present invention described above, the description has been mainly made on the assumption that the current control system operates as a self-sustained operation mode separated from the system.

  Therefore, in the following, a current control system that operates as a grid interconnection mode connected to the grid will be described. In order to simplify the description, the current control system 100 according to the first embodiment will be described as an example.

  FIG. 17 shows functional blocks of the current control system 100 that operates in the grid connection mode. As shown in FIG. 17, the system 890 and the power distribution network 880 are connected by closing the mode changeover switch 204. Further, the second electric device 110 operates as a voltage source. This is because the system 890 serves as a voltage source.

  Here, the above-described harmonic suppression guideline (Non-Patent Document 1) stipulates that the current output from the power generation cooperation PCS 202 to the power distribution network 880 must be a sine wave. Therefore, the determination unit 214 included in the current control device 200 determines the second current so as to have a waveform obtained by subtracting the waveform of the first current from the sine waveform that is a predetermined current waveform in the grid connection mode.

  FIG. 18A shows input / output of the current control device 200. As illustrated in FIG. 18A, the current control device 200 that has acquired the SB current, the FC current, the load current, and the main information outputs a command value to the second control unit 114 and the first control unit 124.

  FIG. 18B is a conceptual diagram illustrating mode switching processing performed by the current control device 200. When acquiring the main information, the current control device 200 determines one of the grid interconnection mode and the independent operation mode. Thereafter, a different command value for each determined mode is notified to the second control unit 114 and the first control unit 124.

  More specifically, in the self-sustained operation mode, the current control device 200 sends a command value to the first control unit 124 so that a stable rectangular wave is output from the first electric device 120. This is called current source control. In addition, the current control device 200 sends a command value to the second control unit 114 so as to output a non-linear voltage according to the command value from the second electric device 110. This is called command value voltage source control.

  On the other hand, in the grid connection mode, the current control device 200 can use the grid 890 as a voltage source. In addition, the current control device 200 is required to control the second electric device 110 and the first electric device 120 in accordance with the harmonic suppression countermeasure guideline. Therefore, the current control device 200 controls the second electric device 110 and the first electric device 120 so as to operate as both current sources. In the present embodiment, the first electric device 120 converts the current generated by the FC 129. Therefore, the current control device 200 sends a command value to the first control unit 124 so that a current having a constant amplitude is output from the first electric device 120. This is called fixed current source control. The second electric device 110 converts the voltage of the current discharged by the SB 119 or the voltage of the current to be charged in the SB 119. Therefore, the current control device 200 sends a command value to the second control unit 114 so that a current having a variable amplitude is output from the second electrical device 110. This is called variable current source control.

  Next, with reference to FIG. 19, the process of the calculating part 212 in a grid connection mode is demonstrated. FIG. 19 shows an example of functional blocks of the calculation unit 212. Note that the rise time detection unit 302, the current on time calculation unit 304, and the current amplitude calculation unit 306 illustrated in FIG. 8 are not used in the grid interconnection mode, and thus are not described.

I _FC + i _SB is input to the SB current command value determination unit 310 of the calculation unit 212 as a target value to be output by the creation cooperation PCS 202. This is called a created current command value. Further, the FC current command value that is the current command value notified to the first control unit 124 is also input to the SB current command value determining unit 310.

It should be noted _{that, i FC} is determined by the rating of the FC129. Further, i _SB is determined by the operation of the current control system 100. As the operation of the current control system 100, for example, a local production and local consumption operation such as a so-called microgrid, and a time shift operation in which power is purchased from the system at night and surplus power is sold in the daytime are assumed. In the local production for local consumption operation, the size of i _SB including positive and negative can be frequently changed so that the buying and selling of electric power becomes ± 0. On the other hand, in the time shift operation, i _SB may be determined to be negative (charge direction) mainly at night and to be positive (discharge direction) during the daytime.

  Thereafter, the SB current command value determination unit 310 outputs a difference obtained by subtracting the FC current command value from the created current command value to the determination unit 214. This difference is notified to the second control unit 114 by the notification unit 216 as an SB current command value that is a current command value for the second electrical device 110.

  FIG. 20 is a flowchart showing a flow of processing performed by the current control device 200 in the grid connection mode.

  First, the calculation unit 212 acquires a created current command value and an FC current command value (S240).

  Next, the SB current command value determination unit 310 subtracts the FC current command value from the created current command value. From the obtained difference, a current waveform to be output to the second electrical device 110 is determined (S242).

  Finally, the notification unit 216 notifies the second control unit 114 of a current command value corresponding to the determined current waveform (S244).

  The waveform of the current generated by the current command value determined as described above will be described with reference to FIGS. 21A and 21B.

  FIG. 21A is a conceptual diagram showing the SB 119 and the FC 129 that supply power to the load device in the grid connection mode. FIG. 21B is a diagram for explaining a waveform of a current output from the SB 119 and the FC 129. The vertical axis of FIG. 21B is current [A], and the horizontal axis is time [s].

As shown in FIG. 21A, system 890 outputs voltage V _GRID . Further, the voltage source 110 outputs a current i _SB . Further, the current source 120 outputs a current i _FC .

Here, the current control system 100 is connected to the grid 890. Therefore, i _SB + i _FC , which is the current output by the creation cooperation PCS 202, must be a sine wave whose phase and frequency match the system power. The amplitude of the sine wave is determined according to the total output power of SB119 and FC129. Therefore, the waveform of i _SB + i _FC is determined.

On the other hand, a square wave _{i FC} is amplitude Sadamari rated output of FC129, phase and period determined by the rising timing of _{i LOAD. Furthermore, i SB is} determined by subtracting the _{i FC} from _i SB ₊ i _FC. As a result, the shape of i _SB becomes a non-linear waveform as shown in FIG. 21B.

  According to the current control device 200 according to the present embodiment as described above, even when the connection state with the system 890 is changed by the mode switch 204, appropriate current control is performed according to the connection state. Can do.

  Heretofore, the current control system 100 according to Embodiments 1 and 2 of the present invention has been described in each of the independent operation mode and the grid connection mode. The present invention is not limited to this embodiment.

  For example, consider a case where the load connected to the grid is supplied with current by the current control system 100 is constant. At this time, the current control device 200 may not include the acquisition unit 210. The current control device 200 can know the load current without the acquisition unit 210. Therefore, even if it does not have the acquisition part 210, the electric current control apparatus 200 has the effect of the same invention. Further, the calculation result by the calculation unit 212 does not change. Therefore, even when the current control device 200 does not include the calculation unit 212, the same effect of the invention can be obtained.

  In the grid connection mode, the grid 890 is a voltage source. Therefore, the current control system 100 may not include the second electric device 110. By using the first electric device 120 as a current source and using the system 890 as a voltage source, the current control system 100 can supply power to the load.

  In the first and second embodiments, the first electric device 120 and the second electric device 110 do not include the SB 119 and the FC 129, respectively. However, a unit that combines an electric device that functions as a current source or a voltage source and a storage battery or a power generation device may be used. For example, the first electric device 120 may have the FC 129 therein. Similarly, the second electric device 110 may have the SB 119 therein.

  Each processing unit included in the current control devices according to the first and second embodiments is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

  The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out integration of processing units using that technology. Biotechnology can be applied.

  Moreover, you may combine at least one part among the functions of the current control system which concerns on the said Embodiment 1 or 2, a current control apparatus, and its modification.

  Further, various modifications in which the present embodiment is modified within the scope conceived by those skilled in the art are also included in the present invention without departing from the gist of the present invention.

  Moreover, all the numbers used above are illustrated for specifically explaining the present invention, and the present invention is not limited to the illustrated numbers. Furthermore, the logic levels represented by high / low or the switching states represented by on / off are illustrative for the purpose of illustrating the present invention, and different combinations of the illustrated logic levels or switching states. Therefore, it is possible to obtain an equivalent result. Furthermore, the configuration of the logic circuit shown above is exemplified for specifically explaining the present invention, and an equivalent input / output relationship can be realized by a logic circuit having a different configuration.

  Similarly, the current control method by the current control device is for illustrating the present invention in detail, and the current control method by the current control device according to the present invention includes all of the above steps. It is not always necessary to include it. In other words, the current control method according to the present invention needs to include only the minimum steps that can realize the effects of the present invention. In addition, the order in which the above steps are executed is for illustration in order to specifically describe the present invention, and may be in an order other than the above. Also, some of the above steps may be executed simultaneously (in parallel) with other steps.

  Note that part of the functions of the current control device 200, the current control device 200A, and the current control system 100 and the current control system 100A described in the first and second embodiments can be realized by a computer. Hereinafter, the current control device 200, the current control device 200A, and the functions of the current control system 100 and the current control system 100A that can be realized by a computer are referred to as a current control device or the like. FIG. 22 is a block diagram illustrating a hardware configuration of a computer system that implements a current control device and the like.

  The current control device or the like includes a computer 34, a keyboard 36 and a mouse 38 for giving instructions to the computer 34, a display 32 for presenting information such as a calculation result of the computer 34, and a program executed by the computer 34. A CD-ROM (Compact Disc-Read Only Memory) device 40 for reading and a communication modem (not shown) are included.

  A program that is a process performed by the current control device or the like is stored in a CD-ROM 42 that is a computer-readable medium, and is read by the CD-ROM device 40. Alternatively, the data is read by the communication modem 52 through a computer network.

  The computer 34 includes a CPU (Central Processing Unit) 44, a ROM (Read Only Memory) 46, a RAM (Random Access Memory) 48, a hard disk 50, a communication modem 52, and a bus 54.

  The CPU 44 executes a program read via the CD-ROM device 40 or the communication modem 52. The ROM 46 stores programs and data necessary for the operation of the computer 34. The RAM 48 stores data such as parameters at the time of program execution. The hard disk 50 stores programs and data. The communication modem 52 communicates with other computers via a computer network. The bus 54 connects the CPU 44, the ROM 46, the RAM 48, the hard disk 50, the communication modem 52, the display 32, the keyboard 36, the mouse 38, and the CD-ROM device 40 to each other.

  Furthermore, some or all of the constituent elements constituting each of the above-described devices may be configured by a single system LSI (Large Scale Integrated Circuit). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on a single chip, and specifically, a computer system including a microprocessor, ROM, RAM, and the like. . A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor operating according to the computer program.

  Furthermore, some or all of the constituent elements constituting each of the above-described devices may be configured from an IC card that can be attached to and detached from each device or a single module. The IC card or module is a computer system that includes a microprocessor, ROM, RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

  Further, the present invention may be the method described above. Moreover, it is good also as a computer program which implement | achieves these methods with a computer. Further, it may be a digital signal composed of a computer program.

  Furthermore, the present invention provides a computer-readable recording medium such as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray Disc). (Registered trademark)), a memory card such as a USB memory or an SD card, or a semiconductor memory. Further, the digital signal may be recorded on these recording media.

  Further, the present invention may transmit the computer program or the digital signal via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.

  The present invention may be a computer system including a microprocessor and a memory, wherein the memory stores the computer program, and the microprocessor operates according to the computer program.

  In addition, the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like and executed by another independent computer system. You may do that.

  Furthermore, the above embodiment and the above modification examples may be combined.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a current control system and the like. In particular, the present invention can be applied to a current control system that supplies current to a load device by controlling a current source.

32 Display 34 Computer 36 Keyboard 38 Mouse 40 CD-ROM device 42 CD-ROM
44 CPU
46 ROM
48 RAM
50 Hard disk 52 Communication modem 54 Bus 100, 100A, 900 Current control system 110 Second electrical equipment (voltage source, voltage source)
111 Bidirectional DC / DC converter 112, 912 Bidirectional voltage source inverter 113, 913, 923 LC filter 114 Second controller 119, 919 SB
120 First electrical device (current source, current source)
121, 131 One-way DC / DC converter 122, 132 One-way current source inverter 124, 134 First controller 129, 929 FC
130 Third electrical equipment (current source)
139 PV
150A, 150B Load 200, 200A Current control device 202, 202A Creation / Cooperation PCS
204 Mode changeover switch 210 Acquisition unit 212 Calculation unit 214 Determination unit 216 Notification unit 302 Rise time detection unit 304 Current on time calculation unit 306 Current amplitude calculation unit 310 SB current command value determination unit 870 Current sensor 880 Distribution network 890 System 910 Voltage source 911 Bidirectional DC / DC converter 920 Current source 921 Unidirectional DC / DC converter 922 Unidirectional voltage source inverter 930 Current control device 950A, 950B Load

Claims (7)

A first electrical device that outputs a first current to a distribution network to which the load device is connected;
A second electrical device that outputs a second current to the distribution network;
A current control system that supplies a current to the load device by controlling the first electric device and the second electric device;
The first electrical device is a current source that outputs the first current, which is a current obtained by subjecting a supplied direct current to pulse width modulation, to the distribution network,
The current controller is
The waveform of the first current output from the first electrical device is a rectangular wave, and the waveform of the second current output from the second electrical device is changed from a predetermined current waveform to the waveform of the first current. A determination unit for determining a current to be output to each of the first electric device and the second electric device so as to obtain a waveform obtained by subtracting
A command value for causing the first electrical device to output the determined first current is notified to the first electrical device, and the determined second current is output to the second electrical device. A notification unit that notifies the second electrical device of a command value for the current control system. Each of the first electric device and the second electric device has a switching element for converting the waveform of the supplied current,
The switching frequency, which is the switching frequency of the switching element of the first electrical device, is 100 Hz or 120 Hz,
The current control system according to claim 1, wherein a switching frequency of a switching element included in the second electric device is 1 kHz to 100 kHz or less. The current control system further includes a mode changeover switch that switches between a grid connection mode in which the current control system operates in conjunction with a power system and a self-sustained operation mode in which the current control system operates by being disconnected from the power system. Including
The current control device includes an acquisition unit that acquires information about a load current that is a current supplied to the load device,
In the autonomous operation mode,
The current control device controls the second electric device as a voltage source,
The determining unit determines the second current to be a waveform obtained by subtracting the waveform of the first current from the waveform of the load current that is the predetermined current waveform,
In the grid connection mode,
The current control device controls the second electric device as a current source,
The current control system according to claim 1, wherein the determining unit determines the second current to have a waveform obtained by subtracting the waveform of the first current from a sine waveform that is the predetermined current waveform. The current control system further includes a mode changeover switch for switching between a grid connection mode in which the current control system operates in conjunction with a power system and a self-sustained operation mode in which the current control system operates by being disconnected from the power system. When,
A third electrical device that is a current source that outputs a third current different from the first current and the second current;
The current control device includes an acquisition unit that acquires information about a load current that is a current supplied to the load device,
In the autonomous operation mode,
The current control device controls the second electric device as a voltage source,
The determining unit determines the second current to be a waveform obtained by subtracting the waveform of the first current and the third current from the waveform of the load current that is the predetermined current waveform,
In the grid connection mode,
The current control device controls the second electric device as a current source,
2. The current control according to claim 1, wherein the determination unit determines the second current to have a waveform obtained by subtracting the waveforms of the first current and the third current from a sine waveform that is the predetermined current waveform. system. The determining unit further determines the waveform of the first current so that a waveform obtained by adding the waveform of the first current and the waveform of the third current approximates the waveform of the load current in the independent operation mode. Decide
The waveform of the first current is determined so that a waveform obtained by adding the waveform of the first current and the waveform of the third current approximates the sine waveform in the grid connection mode. Current control system. A current control device that controls a first electrical device that outputs a first current to a distribution network to which a load device is connected, and a second electrical device that outputs a second current to the distribution network,
The first electrical device is a current source that outputs the first current, which is a current obtained by subjecting a supplied direct current to pulse width modulation, to the distribution network,
The waveform of the first current output from the first electrical device is a rectangular wave, and the waveform of the second current output from the second electrical device is changed from a predetermined current waveform to the waveform of the first current. A determination unit for determining a current to be output to each of the first electric device and the second electric device so as to obtain a waveform obtained by subtracting
A command value for causing the first electrical device to output the determined first current is notified to the first electrical device, and the determined second current is output to the second electrical device. A notification unit that notifies the second electrical device of a command value for the current control device. A current control method for controlling a first electrical device that outputs a first current to a distribution network to which a load device is connected, and a second electrical device that outputs a second current to the distribution network,
The first electrical device is a current source that outputs the first current, which is a current obtained by subjecting a supplied direct current to pulse width modulation, to the distribution network,
The waveform of the first current output from the first electrical device is a rectangular wave, and the waveform of the second current output from the second electrical device is changed from a predetermined current waveform to the waveform of the first current. Determining the current to be output to each of the first electric device and the second electric device so as to obtain a waveform obtained by subtracting
A command value for causing the first electrical device to output the determined first current is notified to the first electrical device, and the determined second current is output to the second electrical device. A notification step of notifying the second electrical device of a command value for the current control method.

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