CN113615028A - Control device, system, control method, and program - Google Patents

Control device, system, control method, and program Download PDF

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Publication number
CN113615028A
CN113615028A CN202080023071.7A CN202080023071A CN113615028A CN 113615028 A CN113615028 A CN 113615028A CN 202080023071 A CN202080023071 A CN 202080023071A CN 113615028 A CN113615028 A CN 113615028A
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China
Prior art keywords
voltage
bus
power
converters
control
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CN202080023071.7A
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Chinese (zh)
Inventor
丸山宏二
藤田悟
长野刚
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Fuji Electric Co Ltd
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Fuji Electric Co Ltd
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Publication of CN113615028A publication Critical patent/CN113615028A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/102—Parallel operation of dc sources being switching converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

In the related art, an overvoltage may be generated between the DC/DC converter and the inverter due to a problem of a system or the like. The present invention provides a control device, including: a first control unit that controls at least one of a plurality of DC/DC converters provided between a DC bus maintained at a reference voltage by power exchange with an inverter and a plurality of DC power sources that supply DC power to the DC bus, respectively; and a voltage measurement unit that measures a voltage of the DC bus, wherein the first control unit reduces output power of only a part of the plurality of DC/DC converters when the voltage of the DC bus exceeds a threshold voltage higher than a reference voltage.

Description

Control device, system, control method, and program
Technical Field
The invention relates to a control device, a control system, a control method, and a program.
Background
Conventionally, various control methods have been proposed for a power system in which power is exchanged between a DC/DC converter connected to a DC power supply such as a solar power generator and an inverter (see, for example, patent document 1).
Patent document 1: japanese patent laid-open No. 2014-171359
Patent document 2: japanese patent laid-open No. 2016 & 158434
Patent document 3: japanese patent laid-open publication No. 2016-220480
Technical problem to be solved by the invention
However, in the conventional technique, an overvoltage may occur between the DC/DC converter and the inverter due to a problem of a system or the like.
Disclosure of Invention
In order to solve the above problem, a first aspect of the present invention provides a control device. The control device may include a first control portion that controls at least one of a plurality of DC/DC converters provided respectively between a direct-current bus maintained at a reference voltage by power exchange with the inverter and a plurality of direct-current power supplies that supply direct current to the direct-current bus. The control device may include a voltage measuring unit that measures a voltage of the dc bus. The first control unit may decrease the output power of only a part of the plurality of DC/DC converters when the voltage of the DC bus exceeds a threshold voltage higher than the reference voltage.
The first control unit may control any corresponding one of the plurality of DC/DC converters.
The control device may further include a changing unit that changes the threshold voltage with time.
When the duration in which the voltage of the DC bus exceeds the threshold voltage exceeds the upper limit time, the first control unit may decrease the output power of the corresponding DC/DC converter. The control device may further include a changing unit that changes the upper limit time with time.
In a second aspect of the invention, a system is provided. The system may include an inverter that maintains the dc bus at a reference voltage through power exchange with the dc bus. The system may include a plurality of DC/DC converters respectively disposed between the DC bus and a plurality of DC power sources that provide DC power to the DC bus. The system may include a plurality of control devices of the first mode that respectively control any corresponding one of the plurality of DC/DC converters.
In the case where the voltage of the direct current bus exceeds the threshold voltage, the plurality of control devices may set a time difference between the plurality of DC/DC converters so as to reduce the output power of each DC/DC converter.
The system may further include other control devices having a second control section that controls the inverter. The second control unit may decrease the output power output from the inverter in response to receiving the command signal for output limitation.
In the control device of the first aspect, the first control portion may control each of the plurality of DC/DC converters.
The first control portion may set a time difference between the plurality of DC/DC converters so as to reduce the output power of each of the DC/DC converters when the voltage of the direct current bus exceeds the threshold voltage.
When the voltage of the DC bus exceeds the threshold voltage, the first controller may increase the number of DC/DC converters that reduce the output power among the plurality of DC/DC converters in a stepwise manner.
The first control portion may decrease the output power of each DC/DC converter in an order corresponding to the maximum output power of each DC power supply connected to each DC/DC converter when the voltage of the DC bus exceeds the threshold voltage.
The control device may further include a storage section that stores inherent threshold voltages that are different from each other above the threshold voltage and that are associated with each of the plurality of DC/DC converters. The first control section may decrease the output power of the DC/DC converter corresponding to any intrinsic threshold voltage when the voltage of the DC bus exceeds the intrinsic threshold voltage.
The control device may further include a storage section that stores inherent upper limit times that are associated with each of the plurality of DC/DC converters and are different from each other. When the duration in which the voltage of the DC bus exceeds the threshold voltage exceeds any inherent upper limit time, the first control unit may decrease the output power of the DC/DC converter corresponding to the inherent upper limit time.
The first control unit may decrease the output power of each DC/DC converter in a random order when the voltage of the DC bus exceeds the threshold voltage.
In a third aspect of the invention, a system is provided. The system may include an inverter that maintains the dc bus at a reference voltage through power exchange with the dc bus. The system may include a plurality of DC/DC converters respectively disposed between the DC bus and a plurality of DC power sources that provide DC power to the DC bus. The system may include a control device of a first manner of controlling each of the plurality of DC/DC converters.
The control device may further include a second control portion that controls the inverter. The second control unit may decrease the output power output from the inverter in response to receiving the command signal for output limitation.
In the system according to the second or third aspect, the second control unit may determine the amount of current flowing through the inverter based on the target output power included in the command signal and the voltage of the dc bus.
The inverter may have a plurality of DC/DC converter circuits connected in parallel to the DC bus in each phase of the output. The inverter may have a plurality of single-phase inverter circuits that are connected in series with each other on the output side in each phase of the output and receive power supply from the respective corresponding DC/DC converters.
Each of the plurality of DC/DC converters may be detachably connected to at least one of the direct current power supply and the direct current bus.
At least a portion of the plurality of dc power sources may be solar power generation devices. The first control unit that controls a DC/DC converter connected to a solar power generation device can further control the solar power generation device, and can perform MPPT control so that maximum power is supplied from the solar power generation device when the voltage of a DC bus is at least one of a threshold voltage or less and a case where the output power of the DC/DC converter is not reduced.
When the output power of some of the DC/DC converters is reduced, the first control unit may control the output power to a target value determined in accordance with the voltage of the DC bus.
When the output power of a part of the DC/DC converters is to be reduced, the first control unit may cancel the control for reducing the output power in accordance with a case where the target value is equal to or greater than at least one of the reference output power of the DC/DC converter and the reference output power of the DC power supply connected to the DC/DC converter.
In a fourth aspect, the present invention provides a control method. The control method may include a control phase in which at least one of a plurality of DC/DC converters respectively provided between a direct current bus maintained at a reference voltage by power exchange with the inverter and a plurality of direct current power supplies that supply direct current to the direct current bus is controlled. The control method may comprise a voltage measurement phase of measuring the voltage of the dc bus. In the control phase, when the voltage of the direct current bus exceeds a threshold voltage higher than the reference voltage, the output power of only a part of the plurality of DC/DC converters can be reduced.
A fifth aspect of the present invention provides a program. The program may cause the computer to realize a first control section that controls at least one of a plurality of DC/DC converters provided respectively between a DC bus maintained at a reference voltage by power exchange with the inverter and a plurality of DC power sources that supply DC power to the DC bus. The program may cause the computer to implement a voltage measuring unit that measures the voltage of the dc bus. The first control unit may decrease the output power of only a part of the plurality of DC/DC converters when the voltage of the DC bus exceeds a threshold voltage higher than the reference voltage.
In addition, the above summary of the invention does not list all the necessary features of the present invention. In addition, sub-combinations of these feature groups may also constitute the invention.
Drawings
Fig. 1 shows a power system 1 according to the present embodiment.
Fig. 2 shows the DC/DC converter 3.
Fig. 3 shows a further DC/DC converter 3.
Fig. 4 shows the unit 25.
Fig. 5 shows the operation of the three-phase inverter 2.
Fig. 6 shows the operation of the control device 5.
Fig. 7 shows a power system 1A according to a first modification.
Fig. 8 shows the control device 7.
Fig. 9 shows the operation of the control device 7.
Fig. 10 shows an operation of the control device 5A.
Fig. 11 shows a state transition diagram of the power system 1A.
Fig. 12 shows a power system 1A according to a second modification.
Fig. 13 shows the operation of the control device 5B.
FIG. 14 illustrates an example of a computer 2200 that can embody the various aspects of the invention in whole or in part.
Detailed Description
The present invention will be described below with reference to embodiments thereof, but the following embodiments are not intended to limit the invention according to the claims. In addition, the combination of the features described in the embodiments is not all necessary for the technical means to solve the technical problems of the present invention.
[1. Power System 1]
Fig. 1 shows a power system 1 according to the present embodiment. The power system 1 includes a three-phase inverter 2 and a plurality of DC/DC converters 3 connected to a DC bus 10, a DC power supply 4 connected to the DC/DC converters 3, and a plurality of control devices 5. A load, not shown, may also be connected to the dc bus 10. Capacitors, not shown, may be provided between the DC bus 10 and at least one of the DC/DC converter 3, the three-phase inverter 2A, and the load.
[1.1. three-phase inverter 2]
The three-phase inverter 2 is an example of an inverter, and performs power conversion between direct current power and alternating current power (three-phase alternating current power in the present embodiment). The three-phase inverter 2 maintains the dc bus 10 at a reference voltage by exchanging power with the dc bus 10. For example, the three-phase inverter 2 may be a PCS (Power conditioning System), may DC/AC convert direct current supplied from the direct current bus 10 and output from the alternating current wiring 15, and AC/DC convert alternating current supplied from the alternating current wiring 15 and supply to the direct current bus 10. The three-phase inverter 2 can maintain the dc bus 10 at the reference voltage by changing the control conditions for power conversion. As an example, a 3.3kV or 6.6kV power system may be connected to the ac wiring 15.
The three-phase inverter 2 may have a voltage measuring section 20, a second control section 21, and a single-phase inverter 22 for each output phase of the U-phase, the V-phase, and the W-phase.
The voltage measuring unit 20 measures the voltage of the dc bus 10. The voltage measuring unit 20 can supply the measured voltage to the second control unit 21.
The second control part 21 passes the control signal Ctrl_DC/ACEach single-phase inverter 22 is controlled. For example, the second control unit 21 may change the control conditions of the individual single-phase inverters 22 based on the measured voltage obtained by the voltage measuring unit 20, and maintain the voltage of the dc bus 10 at the reference voltage.
Each single-phase inverter 22 may be an inverter of a so-called SST (Solid-State Transformer) type. For example, the single-phase inverter 22 may have three DC/DC converter circuits 23 and three single-phase inverter circuits 24. However, the number of the DC/DC converter circuits 23 and the number of the single-phase inverter circuits 24 may be two, four or more, the same number, or different numbers.
In the present embodiment, as an example, three DC/DC converter circuits 23 are connected in parallel with the direct-current bus 10, DC/DC convert the direct-current voltage from the direct-current bus 10, respectively, and supply the converted voltage to the single-phase inverter circuit 24. The three single-phase inverter circuits 24 are connected to the DC/DC converter 3 on the input side, receive power supply from the DC/DC converter 3, and are connected to each other in series on the output side. Thereby, the single-phase inverter 22 adds and outputs the output voltages from the three single-phase inverter circuits 24.
In addition, in the present embodiment, as one example, the DC/DC converter circuits 23 and the single-phase inverter circuits 24 may be in one-to-one correspondence, and each corresponding pair of the DC/DC converter circuit 23 and the single-phase inverter circuit 24 may form the unit 25. The U-phase, V-phase, and W-phase single-phase inverters 22 are connected to each other by star connection (also referred to as Y connection), but may be connected to each other by delta connection (also referred to as Δ connection). Further, the three-phase inverter 2 and the direct current bus 10 may be housed in a single case to form a PCS (Power Conditioning System) device 11. Such a PCS device 11 may be formed as a rack mount type that can be disposed so as to house a plurality of DC/DC converters 3.
[1.2.DC/DC CONVERTER 3]
The plurality of DC/DC converters 3 are respectively provided between the DC bus 10 and the plurality of DC power supplies 4, and DC/DC convert the DC power from the DC power supplies 4 and supply the DC power to the DC bus 10. In the present embodiment, three DC/DC converters 3 (also referred to as DC/DC converters 3a to 3c) are provided in the power system 1 as an example, but the number of DC/DC converters 3 may be two, or four or more. Each DC/DC converter 3 may be detachably connected to at least one of the direct-current power supply 4 and the direct-current bus 10. Each DC/DC converter 3 may be connected to the direct current bus 10 by being housed in a rack-mounted PCS device 11.
[1.3. DC Power supply 4]
A plurality of dc power supplies 4 provide dc power to a dc bus 10. In the present embodiment, as an example, the power system 1 includes three direct-current power supplies 4 (also referred to as direct-current power supplies 4a to 4c) having the same number as the number of DC/DC converters 3, and each direct-current power supply 4 supplies a direct-current power to the direct-current bus 10 via a corresponding single DC/DC converter 3. Each of the dc power supplies 4 may be a distributed power supply, and at least a part of the plurality of dc power supplies 4 may be a household solar power generation apparatus that outputs several kW of electric power or a commercial solar power generation apparatus that outputs several MW of electric power. In the present embodiment, the dc power supplies 4a and 4b are solar power generators, and the dc power supply 4c is a battery, as an example.
[1.4. control device 5]
The plurality of control devices 5 control the plurality of DC/DC converters 3. Each control device 5 includes a voltage measuring unit 50, a first control unit 51, and a changing unit 52.
The voltage measuring unit 50 measures the voltage of the dc bus 10. The voltage measuring unit 50 can supply the measured voltage to the first control unit 51.
The first control unit 51 controls the signal Ctrl u via the control signal CtrlDC/DCTo control at least one DC/DC converter 3 among the plurality of DC/DC converters 3, and in the present embodiment, any one of the corresponding DC/DC converters 3 is controlled as an exampleA DC/DC converter 3. When the voltage of the DC bus 10 exceeds the threshold voltage, the first control unit 51 reduces the output power of only some of the plurality of DC/DC converters 3. For example, the first control unit 51 may reduce the output power of the corresponding DC/DC converter 3.
The threshold voltage may be a voltage higher than a reference voltage maintained by the three-phase inverter 2 and lower than an absolute maximum rated voltage. In the case where a problem occurs in the power system 1 or the amount of power supplied from the dc power supplies 4a and 4b as the solar power generation devices is larger than the capacity of the load connected to the dc bus 10 or the dc power supply 4c as the storage battery, the voltage of the dc bus 10 may become higher than the reference voltage. The threshold voltage may be different between the plurality of control devices 5.
In this case, when the voltage of the direct current bus 10 exceeds the threshold voltage of each control device 5, the plurality of control devices 5 decrease the output power of each DC/DC converter 3 by setting a time difference between the plurality of DC/DC converters 3. When the voltage of the DC bus 10 exceeds the threshold voltage of each of the control devices 5, the plurality of control devices 5 increase the number of DC/DC converters that reduce the output power among the plurality of DC/DC converters 3 in a stepwise manner. In addition, the first control portion 51 may stop the DC/DC converter 3 when the voltage of the direct current bus 10 exceeds the absolute maximum rated voltage.
The changing unit 52 changes the threshold voltage of the first control unit 41 with time. Thus, the order of the threshold voltages changes with time between the plurality of control devices 5. Even when the default threshold voltages are equal among the plurality of control devices 5, the threshold voltages are different among the plurality of control devices 5.
The changing unit 52 maintains the threshold voltage higher than the reference voltage. The changing unit 52 may change the threshold voltage randomly or periodically.
According to the above power system 1, when the voltage of the direct current bus 10 exceeds the threshold voltage, the output power of some of the plurality of DC/DC converters 3 decreases. Therefore, even when a problem occurs in the power system 1 or when the amount of power supplied from the dc power supplies 4a and 4b as the solar power generation devices exceeds the capacity of the load of the dc bus 10 or the dc power supply 4c as the battery, the voltage of the dc bus 10 can be suppressed to be equal to or lower than the threshold voltage, thereby preventing overvoltage and damage to the device. Further, since the voltage of the DC bus 10 is maintained at the reference voltage by the power exchange with the three-phase inverter 2, and when the voltage exceeds the threshold voltage, the output power of a part of the DC/DC converter 3 is reduced to be lower than the threshold voltage, and thus the control of the voltage of the DC bus 10 can be dispersed between the control of the three-phase inverter 2 and the control of the DC/DC converter 3, unlike the case where the voltage of the DC bus 10 is controlled to be lower than the threshold voltage only by the control of the three-phase inverter 2, thereby simplifying the control. Further, since the control of the voltage of the DC bus 10 can be distributed between the control of the three-phase inverter 2 and the control of the DC/DC converter 3, the degree of freedom in the number of the DC/DC converters 3 or the DC power supplies 4 of the power system 1 can be increased, and the number of the DC/DC converters 3 or the DC power supplies 4 can be increased or decreased without changing the control configuration of the three-phase inverter 2. Further, when the voltage of the DC bus 10 exceeds the threshold voltage, the output power of only a part of the DC/DC converters 3 is reduced, and thus the entire power system 1 can be continuously operated.
Since each of the first control units 51 controls one of the corresponding DC/DC converters 3, the corresponding DC/DC converter 3 can be controlled regardless of how many other DC/DC converters 3 are provided in the power system 1. Therefore, the number of DC/DC converters 3 can be arbitrarily increased or decreased.
Further, since the threshold voltage of the first control unit 51 changes with time by the changing unit 52 of each control device 5, even when the default threshold voltages are equal among the plurality of control devices 5 provided in the power system 1, the threshold voltage can be made different from those of the other control devices 5. Therefore, since the plurality of DC/DC converters 3 can be controlled based on the individual threshold voltages, when the voltage of the DC bus 10 rises, the output power of all the DC/DC converters 3 can be prevented from being reduced, and the operation of the entire power system 1 can be reliably continued. Further, since the order of the threshold voltages can be changed with the passage of time between the plurality of control devices 5, when the voltage of the DC bus 10 exceeds the threshold voltage repeatedly occurs, the DC/DC converters 3 to be the target of the output power reduction can be prevented from being relatively concentrated.
Further, when the voltage of the DC bus 10 exceeds the threshold voltage, the plurality of control devices 5 reduce the output power of each of the DC/DC converters 3 by providing a time difference between the plurality of DC/DC converters 3, and thereby, when the voltage of the DC bus 10 rises, it is possible to prevent the output power of all the DC/DC converters 3 from being reduced and reliably continue the operation of the entire power system 1.
Further, at least a part of the plurality of direct current power supplies 4 is a solar power generation device, and therefore, the DC/DC converter 3 can be stopped when the amount of power generation obtained by solar power generation increases and the voltage of the direct current bus 10 exceeds a threshold voltage.
Further, since each DC/DC converter 3 is detachably connected to at least one of the DC power supply 4 and the DC bus 10, the number of the DC power supplies 4 connected to the DC bus 10 can be easily increased or decreased.
Further, since the three-phase inverter 2 includes the plurality of DC/DC converter circuits 23 connected in parallel to the DC bus 10 and the single-phase inverter circuit 24 connected in series to each other on the output side, the output power can be increased as compared with the case where only a single-phase inverter circuit 24 is provided.
[2.DC/DC converter 3]
Fig. 2 shows the DC/DC converter 3. The DC/DC converters 3a and 3b connected to the DC power supplies 4a and 4b serving as the solar power generation devices may be step-up choppers for stepping up voltages supplied from the DC power supplies 4a and 4 b. The DC/DC converter 3 includes a first positive-side terminal 31a and a first negative-side terminal 31b connected to the direct-current power supply 4, a second positive-side terminal 32a and a second negative-side terminal 32b connected to the direct-current bus 10, a diode 33 and a switching element 34 connected in series between the second positive-side terminal 32a and the second negative-side terminal 32b, a filter capacitor 36 provided between the second positive-side terminal 32a and the second negative-side terminal 32b, and an inductor 37 provided between the first positive-side terminal 31a and the diode 33 and the switching element 34. The first negative terminal 31b is connectable to the second negative terminal 32 b.
Fig. 3 shows a further DC/DC converter 3. The DC/DC converter 3 connected to the direct-current power supply 4c as a storage battery may be a bidirectional DC/DC converter that boosts the voltage supplied from the direct-current power supply 4c and supplies it to the direct-current bus 10, and that drops the voltage supplied from the direct-current bus 10 and supplies it to the direct-current power supply 4 c. The DC/DC converter 3 may have a structure in which the diode 33 in the DC/DC converter 3 shown in fig. 2 is replaced with the switching element 35.
[3. Unit 25 of Single-phase inverter 22 ]
Fig. 4 shows the unit 25. The unit 25 has a positive side terminal 251a and a negative side terminal 251b connected to the direct current bus 10, alternating current output terminals 252, 252 connected in series with other units 25, a DC/DC converter circuit 23, and a single-phase inverter circuit 24.
The DC/DC converter circuit 23 may be an insulation type converter, and in the present embodiment, as one example, the DC/DC converter circuit 23 is a full-bridge type bidirectional DC/DC converter. The DC/DC converter circuit 23 includes a transformer 230, a filter capacitor 231 and a full bridge circuit 232 provided between a positive side terminal 251a and a negative side terminal 251b on the primary side of the transformer 230, and a full bridge circuit 234 provided between a positive side wiring 233a and a negative side wiring 233b on the secondary side of the transformer 230. The full-bridge circuit 232 may have switching elements 2321, 2322 and switching elements 2323, 2324 connected in series between the positive-side terminal 251a and the negative-side terminal 251b, and the full-bridge circuit 234 may have switching elements 2341, 2342 and switching elements 2343, 2344 connected in series between the positive-side wiring 233a and the negative-side wiring 233 b. The primary winding 2301 of the transformer 230 may be connected to the midpoints of the switching elements 2321, 2322 and the switching elements 2323, 2324, and the secondary winding 2302 may be connected to the midpoints of the switching elements 2341, 2342 and the switching elements 2343, 2344. The transformer 230 may operate at a high frequency of several tens of kHz (for example, 10kHz to 90kHz), and may be smaller than a transformer for commercial power of 50kHz or 60 kHz.
The single-phase inverter circuit 24 includes a filter capacitor 240 and a full-bridge circuit 241, which are provided in parallel between the positive-side wiring 233a and the negative-side wiring 233 b. The full-bridge circuit 241 may have switching elements 2411 and 2412 and switching elements 2413 and 2414 connected in series between the positive-side wiring 233a and the negative-side wiring 233 b. Midpoints of the switching elements 2411, 2412 and the switching elements 2413, 2414 may be connected to the ac output terminals 252, 252.
When the ac output terminals 252 and 252 of the cell 25 are connected in series with the ac output terminals 252 and 252 of the other cells 25 as described above, the voltage of the smoothing capacitor 240 needs to be kept constant between the connected cells 25. In the power system 1 according to the present embodiment, as described above, the voltage of the DC bus 10 is maintained at the reference voltage by the three-phase inverter 2, and when the voltage of the DC bus 10 exceeds the threshold voltage, the voltage of the smoothing capacitor 240 can be reliably maintained constant because the DC bus 10 is controlled to be equal to or lower than the threshold voltage by the control of some of the DC/DC converters 3.
[4. action ]
[4.1. operation of three-phase inverter 2]
Fig. 5 shows the operation of the three-phase inverter 2. The three-phase inverter 2 maintains the voltage of the dc bus 10 at the reference voltage by performing the processing of steps S11 to S15. When this operation is started, the second control unit 21 of the three-phase inverter 2 can continue to control the single-phase inverters 22.
In step S11, the voltage measuring unit 20 measures the voltage of the dc bus 10. The voltage measuring unit 20 may measure the voltage between the input terminals of the DC/DC converter circuit 23 of the single-phase inverter 22 as long as the voltage of the DC bus 10 is measured.
In step S13, the second control unit 21 determines whether or not the measured voltage is the reference voltage. The reference voltage may be a single voltage value or may be a range of voltage values shown by an upper limit value and a lower limit value. When it is determined that the measured voltage is the reference voltage (step S13; y), the process proceeds to step S11, and when it is determined that the measured voltage is not the reference voltage (step S13; n), the process proceeds to step S15.
Then, in step S15, the second control unit 21 changes the control conditions of the individual single-phase inverters 22 to try to maintain the voltage of the dc bus 10 at the reference voltage. For example, the second control section 21 may change the control conditions such that the output of each single-phase inverter 22 is increased when the measured voltage is higher than the reference voltage, and the output of each single-phase inverter 22 is decreased when the measured voltage is lower than the reference voltage. After the process of step S15, the three-phase inverter 2 may shift the process to step S11.
[4.2 actions of the control device 5]
Fig. 6 shows the operation of the control device 5. The control device 5 performs the processing of steps S21 to S25 to maintain the voltage of the dc bus 10 at or below the threshold voltage.
When this operation is started, the first control unit 51 of the control device 5 can continue to control the corresponding DC/DC converter 3. As an example, the control device 5 of the DC/DC converters 3a, 3b connected to the direct-current Power supplies 4a, 4b as the solar Power generation devices may perform MPPT (Maximum Power Point Tracking) control between itself and the direct-current Power supplies 4a, 4b to supply Maximum Power from the direct-current Power supplies 4a, 4 b. Thereby, the DC/DC converters 3a and 3b can DC/DC convert the direct currents from the direct current power supplies 4a and 4b and supply the converted direct currents to the direct current bus 10. The control device 5 of the DC/DC converter 3c connected to the DC power supply 4c as the battery can charge the DC power supply 4c when an excessive amount of the power supplied from the DC power supplies 4a and 4b as the solar power generation devices occurs, and can discharge the DC power supply 4c when an insufficient amount of the power is generated, in accordance with the voltage variation of the DC bus 10.
Further, in the present embodiment, as an example, the three-phase inverter 2 may perform the processes of steps S11 to S15 while the control device 5 performs the processes of steps S21 to S25. However, the three-phase inverter 2 may also be stopped.
In step S21, the voltage measuring unit 50 measures the voltage of the dc bus 10. The voltage measuring unit 50 may measure the voltage between the output terminals of the DC/DC converter 3 as long as the voltage of the DC bus 10 is measured.
In step S23, the first control unit 51 determines whether or not the measured voltage is equal to or less than a threshold voltage. The threshold voltage may be a single voltage value. When it is determined that the measured voltage is equal to or lower than the threshold voltage (step S23; y), the process proceeds to step S21, and when it is determined that the measured voltage exceeds the reference voltage (step S13; n), the process proceeds to step S25.
In step S25, the first control unit 51 decreases the output power of the corresponding DC/DC converter 3. The output power may be reduced by setting the output power to zero or to a power smaller than the output power at the present time.
Here, in the present embodiment, as an example, the threshold voltage is different among the plurality of control devices 5. Therefore, only some of the plurality of control devices 5 perform the processing of step S25, and as a result, the output power is reduced in only some of the DC/DC converters 3.
The power system 1 is provided with a plurality of control devices 5, and the processing of steps S21 to S25 is performed independently. Therefore, when the threshold voltage is randomly changed by the changing section 52, the output powers of the respective DC/DC converters 3 can be decreased in a random order as the voltage of the direct current bus 10 rises.
In the present embodiment, as an example, the operation of the control device 5 may be completed in step S25. Alternatively, the process may also shift to step S21 after step S25. In this case, when it is determined in the process of step S23 that the measured voltage exceeds the threshold voltage (step S23; n), the first control portion 51 may further reduce the output power of the corresponding DC/DC converter 3 in the process of step S25. As an example, the first control unit 51 may decrease the output power of the DC/DC converter 3 by a predetermined power for each processing of step S25. When the first control unit 51 has set the output power of the DC/DC converter 3 to zero, the first control unit 51 may maintain the output power of the DC/DC converter 3 at zero in the processing of step S25. When the DC power supply 4c as a battery is connected to the DC/DC converter 3, the first control unit 51 may charge the DC power supply 4c with negative output power of the DC/DC converter 3 (power current supplied from the DC bus 10 to the DC/DC converter 3). If it is determined in the process of step S23 that the measured voltage is equal to or lower than the threshold voltage (step S23; "yes"), the first controller 51 may restore the output power of the DC/DC converter 3. The threshold voltage in the case of reducing the output power and the threshold voltage in the case of recovering the output power may be the same voltage, or may be voltages different from each other so as to have a hysteresis characteristic.
In the above-described embodiment, the control device 5 has been described as a device separate from the corresponding DC/DC converter 3, but the control device 5 and the corresponding DC/DC converter 3 may be provided integrally.
Although the DC power supply 4 and the DC/DC converter 3 are described as being equal in number, the number may not be equal. For example, the number of the DC power supplies 4 may be smaller than the number of the DC/DC converters 3, and each of the DC power supplies 4 may be connected to a corresponding one of the plurality of DC/DC converters, or the number of the DC power supplies 4 may be larger than the number of the DC/DC converters 3, and the corresponding one of the plurality of DC power supplies 4 may be connected to each of the plurality of DC/DC converters 3.
Although the control device 5 has been described as having the changing unit 52, the changing unit 52 may not be provided when the fixed threshold voltages are different between the plurality of control devices 5.
Further, although it is described that the first control portion 51 lowers the output power of the DC/DC converter 3 corresponding to the first control portion 51 when the voltage of the direct current bus 10 exceeds the threshold voltage, the output power of the DC/DC converter 3 corresponding to the first control portion 51 may be lowered when the duration in which the voltage of the direct current bus 10 exceeds the threshold voltage exceeds the upper limit time. In this case, the control device 5 may further include a changing unit that changes the upper limit time with time. This makes it possible to make the upper limit time different from the other control devices 5 provided in the power system 1, and thus, the plurality of DC/DC converters 3 can be controlled based on the individual upper limit time. Therefore, when the voltage of the DC bus 10 rises, it is possible to reliably continue the operation of the entire power system 1 while preventing the output powers of all the DC/DC converters 3 from decreasing.
[ 5] modification example 1]
[5.1. Power System 1A ]
Fig. 7 shows a power system 1A according to a first modification. Power system 1A may include a three-phase inverter 2A, a control device 5A, and a control device 7.
The three-phase inverter 2A is externally connected to the control device 7. The three-phase inverter 2A is controlled by a control signal Ctrl supplied from the control device 7_DC/ACAnd (5) controlling.
The control device 5A has a first control unit 51A.
The first control unit 51A controls the DC/DC converter 3a connected to the DC power supply 4a as the solar power generation device. The first control unit 51A may further control the dc power supply 4 a. When the voltage of dc bus 10 is equal to or lower than the threshold voltage, first controller 51A may perform MPPT control so that the maximum power is supplied from dc power supply 4 a.
Further, when the voltage of the DC bus 10 exceeds the threshold voltage and the output power of some of the plurality of DC/DC converters 3 (corresponding DC/DC converters 3a in the present modification) is reduced, the first control unit 51A may control the output power to a target value determined based on the voltage of the DC bus 10. In addition, regarding the target value, details are described later.
The control device 7 includes a voltage measuring unit 70 and a second control unit 71.
The voltage measuring unit 70 measures the voltage of the dc bus 10. The voltage measuring unit 70 may supply the measured voltage to the second control unit 71.
The second control part 71 passes the control signal Ctrl_DC/ACAt least one single-phase inverter 22 is controlled. In the present modification, as an example, the second control portion 71 may control each single-phase inverter 22. The second control unit 71 may change the control conditions of the individual single-phase inverters 22 based on the measured voltage obtained by the voltage measuring unit 70 so as to maintain the voltage of the dc bus 10 at the reference voltage. Further, the second control portion 71 may be based on receiving the output limitThe condition of the command signal is to decrease the output power output from the single-phase inverter 22. When the output power from the three-phase inverter 2A is larger than the output limit power, a command signal of the output limit may be continuously provided from an operator or an external device. The output limit power may be a rated power of the three-phase inverter 2A, or may be an upper limit value of a power output from the three-phase inverter 2A to the ac wiring 15. In addition, when power consumption generated by a load connected to the dc bus 10 increases, an instruction signal of output limitation may be supplied to the second control section 71.
According to the above power system 1A, since the DC power supply 4a as the solar power generation device is MPPT-controlled when the voltage of the DC bus 10 is equal to or lower than the threshold voltage, the output of the solar power generation device and hence the output of the DC/DC converter 3a can be maximized when it is not necessary to reduce the output of the DC/DC converter 3 a.
Further, when the output power of the DC/DC converter 3 decreases, the output power of the DC/DC converter 3 decreases based on a target value determined based on the voltage of the DC bus 10, and therefore the voltage of the DC bus 10 can be reliably maintained at the reference voltage.
Further, since the output power output from the single-phase inverter 22 is reduced in response to the reception of the command signal for the output limitation by the second control unit 71, it is possible to prevent the output power from the single-phase inverter 22 from being maintained in spite of the command for the output limitation. Further, the output power from the single-phase inverter 22 is reduced, whereby the voltage of the dc bus 10 can be prevented from being reduced by a corresponding amount. As described above, the voltage of DC bus 10 can be increased by maintaining the output of DC/DC converter 3 at a high level by MPPT control or the like, and the voltage of DC bus 10 can be maintained by decreasing the output of DC/DC converter 3. Therefore, the voltage of the dc bus 10 can be reliably maintained at the reference voltage without communication between the control device 7 and the control device 5A.
[5.2. control device 7]
Fig. 8 shows the control device 7. The second control section 71 of the control device 7 has a voltage control section 710, an output limit current calculation section 711, an adjustment section 712, and a switching section 713.
As in the second control unit 21 in the above-described embodiment, the voltage control unit 710 controls each single-phase inverter 22. For example, the voltage control unit 710 may change the control conditions of the individual single-phase inverters 22 based on the measured voltage obtained by the voltage measurement unit 70 so as to maintain the voltage of the dc bus 10 at the reference voltage. The voltage control part 710 may provide the control signal Ctrl to each single-phase inverter 22 via the switching part 713_DC/AC。
The output limiting current calculation unit 711 determines the current flowing through each single-phase inverter 22 when limiting the output power of the single-phase inverter 22. The output-limited-current calculation unit 711 may determine a command value of the amount of current flowing through the single-phase inverter 22 based on the target output power included in the command signal and the voltage of the dc bus 10, in response to the reception of the command signal for output limitation. For example, the output limit current calculation unit 711 may calculate the command value of the current amount (I) by dividing the target output power (W) by the measurement voltage obtained by the voltage measurement unit 70, that is, by the voltage (V) of the dc bus 10. The output limit current calculation part 711 may supply the instruction value of the calculated current amount to the adjustment part 712.
The adjustment unit 712 corrects the command value of the amount of current supplied from the output limiting current calculation unit 711 based on the shortage of the voltage of the dc bus 10 (in the present modification, the measured voltage obtained by the voltage measurement unit 70) with respect to the reference voltage, and controls the adjustment unit 712 to generate the control signal Ctrl for each single-phase inverter 22_DC/ACSo that a current corresponding to the corrected command value flows through the single-phase inverter 22, and the control signal Ctrl may be passed through the switching section 713_DC/ACTo each single-phase inverter 22.
The switching unit 713 outputs the control signal Ctrl output from either the voltage control unit 710 or the adjustment unit 712_DC/ACTo each single-phase inverter 22. When receiving the instruction signal of the output limit, the switching part 713 may adjust the control signal Ctrl from the adjusting part 712_DC/ACIs provided to each single-phase inverter 22, and when no command signal is received, the switching section 713 mayThe control signal Ctrl from the voltage control section 710_DC/ACTo each single-phase inverter 22.
According to the above control device 7, since the amount of current flowing through the single-phase inverter 22 is determined based on the target output power included in the command signal for output limitation and the voltage of the dc bus 10, the target output power can be reliably output from the single-phase inverter 22.
[5.3. actions ]
[5.3(1). operation of the control device 7]
Fig. 9 shows the operation of the control device 7. The control device 7 performs the processing of steps S51 to S67 to control the output voltage of the single-phase inverter 22 and the voltage of the dc bus 10. When this operation is started, the control device 7 can continue to control the single-phase inverters 22.
In step S51, voltage measuring unit 70 measures the voltage of dc bus 10, similarly to step S11 described above.
In step S53, the switching unit 713 determines whether or not the command signal for output restriction has been received. When the output power from the three-phase inverter 2A is larger than the output limit power, a command signal of the output limit may be supplied to the control device 7. If it is determined in step S53 that the command signal for output limitation has not been received (step S53; n), the process proceeds to step S55. If it is determined in step S53 that the command signal for output limitation has been received (step S53; y), the process proceeds to step S61.
In step S55, the switching section 713 selects the voltage control section 710 as the control signal Ctrl_DC/ACThe output source of (1). In step S55, the switching section 713 may enable the voltage control section 710 and disable the adjusting section 712 instead.
In step S57, the voltage measuring unit 710 determines whether or not the measured voltage is the reference voltage, similarly to step S13 described above. When it is determined that the measured voltage is the reference voltage (step S57; y), the process proceeds to step S51, and when it is determined that the measured voltage is not the reference voltage (step S13; n), the process proceeds to step S59.
Then, in step S59, voltage control unit 710 attempts to maintain the voltage of dc bus 10 at the reference voltage by changing the control conditions of each single-phase inverter 22, similarly to step S15 described above. After the process of step S59, the process may shift to step S51.
In the present modification, since the control is performed so that the voltage of the dc bus 10 is maintained through the processing in steps S55 to S59, the state of the control device 7 when the processing in steps S55 to S59 is executed is also referred to as a state in which the dc bus voltage is maintained.
In step S61, the switching section 713 selects the adjustment section 710 as the control signal Ctrl_DC/ACThe output source of (1). In step S61, the switching section 713 may enable the voltage control section 710 and disable the adjusting section 712 instead.
In step S63, the output-limited-current calculation unit 711 determines a command value for the amount of current flowing through the single-phase inverter 22 based on the target output power included in the command signal and the measured voltage of the dc bus 10. The amount of current flowing through the single-phase inverter 22 may be the amount of dc current flowing through the single-phase inverter 22 from the dc bus 10, or may be the amount of ac current output from the single-phase inverter 22 (for example, an effective value).
In step S65, the adjustment unit 712 corrects the command value for the current amount based on the shortage of the measured voltage with respect to the reference voltage. For example, the adjustment unit 712 may decrease the command value of the current amount from the original value as the voltage of the shortage increases. Thus, compared to the case where the specified value of the amount of current is not reduced, the output from the single-phase inverter 22 is reduced, and the voltage drop of the dc bus 10 can be suppressed. The adjustment unit 712 may perform PI control on the command value of the current amount. Thereby, the command value of the current amount is corrected so that the current flowing through the single-phase inverter 22 does not oscillate. In the case where there is no insufficient voltage, that is, in the case where the measured voltage is equal to or higher than the reference voltage, the adjustment unit 712 may not correct the command value of the amount of current.
In step S67, the adjustment unit 712 changes the control conditions of the individual single-phase inverters 22 based on the corrected command value, thereby limiting the current flowing through the individual single-phase inverters 22 to the corrected command value and limiting the output from the individual single-phase inverters 22. As a result, the power output from single-phase inverter 22 decreases, and further, the power output from three-phase inverter 2A decreases, so that the voltage drop of DC bus 10 is alleviated, and the voltage of DC bus 10 increases in accordance with the power supply from DC/DC converter 3. The output power from the three-phase inverter 2A may be smaller than the output limit power. After the process of step S67, the process may shift to step S51.
In the present modification, since the ac output from the three-phase inverter 2A is limited by the processing in steps S61 to S67, the state of the control device 7 when performing the processing in steps S61 to S67 is also referred to as the ac output limited state.
[5.3(2) operation of control device 5A ]
Fig. 10 shows an operation of the control device 5A. The control device 5A performs the processing of steps S71 to S87 to control the output power of the DC/DC converter 3 and the voltage of the DC bus 10. When this operation is started, the first control unit 51A of the control device 5A can continue to control the corresponding DC/DC converter 3 a. Further, in the present modification, as an example, the control device 7 may perform the processing of steps S51 to S67 while the control device 5A performs the processing of steps S71 to S87. However, the control device 7 may also be stopped.
In step S71, voltage measuring unit 50 measures the voltage of dc bus 10, similarly to step S21 described above.
In step S73, the first controller 51A determines whether or not the measured voltage is equal to or less than the reference voltage, similarly to step S23 described above. When it is determined that the measured voltage is equal to or lower than the threshold voltage (step S73; y), the process proceeds to step S75, and when it is determined that the measured voltage exceeds the reference voltage (step S75; n), the process proceeds to step S81.
In step S75, the first control unit 51A performs MPPT control such that the DC power supply 4a serving as the solar power generation device supplies the maximum power to the DC/DC converter 3a and further to the DC bus 10. This increases the voltage of the dc bus 10. After the process of step S75, the process may shift to step S71.
In the present modification, since MPPT control is performed on the dc power supply 4a by the processing in steps S71 to S75, the state of the controller 5A when the processing in steps S71 to S75 is performed is also referred to as the state of MPPT.
In step S81, first control unit 51A controls the output power of DC/DC converter 3a to a target value determined based on the measured voltage of DC bus 10. The target value can be determined based on the measured voltage of the dc bus 10 and the reference voltage used by the second control unit 71.
For example, when the measured voltage is greater than the reference voltage, the target value may be determined to be a value smaller than the target value determined in step S81, and when the measured voltage is less than the reference voltage, the target value may be determined to be a value larger than the target value determined in step S81. The target value may be varied in a range proportional to the magnitude of the difference between the measurement voltage and the reference voltage or may be constant regardless of the magnitude of the difference each time the process of step S81 is performed.
The target value at the time of starting the processing of step S81, that is, the initial value of the target value may be smaller than the output power at the time of MPPT control. Thereby, the output power of the DC/DC converter 3a is reduced from the output power obtained by the processing of step S75. Similarly, each target value when the process of step S81 is repeatedly performed may be smaller than the output power when MPPT control is performed.
When the measured voltage is equal to the reference voltage, the target value may be the same as in step S81. Further, when the amount of solar radiation temporarily decreases and the amount of power generation of the DC power supply 4a, that is, the solar power generator decreases, the output power of the DC/DC converter 3a may be lower than the target value.
The target value may be calculated by the first control unit 51A. Alternatively, the target value may also be provided to the first control portion 51A from outside the control device 5A. The target value may not necessarily be determined based on the reference voltage used by the second control unit 71 and the measured voltage of the dc bus 10. For example, the target value may be determined based on the threshold voltage and the measured voltage used by the first control unit 51A in the processing of step S73, or may be determined based on a voltage and a measured voltage different from each of the reference voltage and the threshold voltage.
In step S83, voltage measuring unit 50 measures the voltage of dc bus 10, similarly to step S21 described above.
In step S85, first control unit 51A determines whether or not the target value is equal to or greater than the reference output power of DC/DC converter 3 a. In the present modification, as an example, the reference output power of the DC/DC converter 3a is the rated output power at which the DC/DC converter 3a can be stably used in design, but may be the maximum output power which the DC/DC converter 3a can temporarily output. If it is determined in step S85 that the target value is not equal to or greater than the reference output power (step S85; n), the process proceeds to step S87. If it is determined in step S85 that the target value is equal to or higher than the reference output power (step S85; y), the process proceeds to step S71. Thereby, the control for reducing the output power of the DC/DC converter 3a by the processing of step S81 is released.
In step S87, the first control unit 51A determines whether or not the target value is equal to or greater than the reference output power of the DC power supply 4a connected to the DC/DC converter 3 a. In the present modification, as an example, the reference output power of the dc power supply 4a is a rated output power at which the dc power supply 4a can be stably used in design, but may be a maximum output power which the dc power supply 4a can temporarily output. After the process of step S87, the process may shift to step S81. If it is determined in step S87 that the target value is not equal to or greater than the reference output power (step S87; n), the process proceeds to step S87. If it is determined in step S87 that the target value is equal to or higher than the reference output power (step S85; y), the process proceeds to step S71. Thereby, the control for reducing the output power of the DC/DC converter 3a by the processing of step S81 is released.
In addition, only one of the processes of steps S85 and S87 may be performed.
In the present modification, since the output power from the DC/DC converter 3a is limited by the processing in steps S81 to S87, the state of the control device 5A when the processing in steps S81 to S87 is performed is also referred to as a state of DC output limitation.
According to the above operation, when the output power of the DC/DC converter 3a is reduced by the processing of step S81, as a result of the voltage of the DC bus 10 being increased by the processing of steps S51 to S67 and the like by the second control unit 71, when the target value of the output power of the DC/DC converter 3a determined based on the voltage of the DC bus 10 is equal to or higher than at least one of the reference output power of the DC/DC converter 3a and the reference output power of the DC power supply 4a connected thereto, the control for reducing the output power is cancelled. Therefore, the control can be switched appropriately without lowering the output power.
Further, when the measured voltage of dc bus 10 exceeds the threshold voltage and control device 5A is in the dc output limitation state, control device 5A is in the MPPT state based on the target value of the output power determined by the measured voltage, and therefore, the state transition of control device 5A can be interlocked with the voltage control of dc bus 10 by control device 7, and communication between control device 5A and control device 7 is not necessary. Further, since the control device 5A is in the MPPT state not based on the measured voltage itself but based on the target value of the output power determined by the measured voltage, it is possible to prevent the state of the control device 5A from being frequently switched.
[5.3(3). State transition Table of Power System 1A ]
Fig. 11 shows a state transition diagram of the power system 1A.
When the signal of the output limit command is provided in the state where the controller 5A is the MPPT and the controller 7 is maintained for the dc bus voltage (S0), that is, when the ac output from the three-phase inverter 2A exceeds the output limit power, the power system 1A is in the state where the controller 5A is the MPPT and the controller 7 is the ac output limit (S1).
When the measured voltage of the dc bus voltage becomes greater than the threshold voltage in the state where the controller 5A is MPPT and the controller 7 is ac output limited (S1), the power system 1A enters a state where the controller 5A is dc output limited and the controller 7 is ac output limited (S2).
When the target value of the DC output power from the DC/DC converter 3a becomes equal to or higher than the reference output power in the state where the controller 5A is the DC output limitation and the controller 7 is the ac output limitation (S2), the power system 1A becomes the state where the controller 5A is the MPPT and the controller 7 is the ac output limitation (S3).
When the command signal for output limitation is not provided in the state where the controller 5A is the MPPT and the controller 7 is the ac output limitation (S3), that is, when the ac output from the three-phase inverter 2A is equal to or less than the output limitation power, the power system 1A is in a state where the controller 5A is the MPPT and the controller 7 is maintained for the dc bus voltage (S0).
Here, in the above state (S0 to S3), in the state where the controller 5A is MPPT and the controller 7 is ac output limitation (S1, S3), the controller 5A and the controller 7 do not perform voltage control of the dc bus 10. Therefore, in this state, when the power supplied from the DC/DC converter 3a to the direct-current bus 10 is lower than the power supplied from the direct-current bus 10 to the three-phase inverter 2A, the voltage of the direct-current bus 10 may be lowered. In this case, the control device 5A cannot increase the supply power from the DC/DC converter 3a, whereas the control device 7 can decrease the supply power to the three-phase inverter 2 a. Therefore, in the present modification, as an example, in step S63, the control device 7 may decrease the command value of the amount of current flowing through the single-phase inverter 22 as the measured voltage of the dc bus 10 decreases. Thereby, the voltage drop of the dc bus 10 is prevented.
In the first modification, the control device 5A has been described as performing the processing of steps S71 to 75 and the processing of steps S81 to S87, respectively, but only either one of the processing may be performed.
In the case where the target value is equal to or higher than the reference output power of the DC/DC converter 3a (step S85; "yes"), or the target value is equal to or higher than the reference output power of the DC power supply 4a connected to the DC/DC converter 3a (step S87; "yes"), the first controller 51A performs the MPPT control when the measured voltage of the DC bus 10 is equal to or lower than the threshold voltage (step S75; "yes"), but the MPPT control may be performed without determining whether the measured voltage is equal to or lower than the threshold voltage. As an example, in the case where the determination result of step S85 or step S87 is yes, the first control portion 51A may shift to the process of step S73 after the MPPT control is performed.
Although the description has been given of the case where the control device 5A controls the DC/DC converter 3a connected to the DC power supply 4a as the solar power generation device, the control device 5A may control the DC/DC converter 3c connected to the DC power supply 4c as the battery. In the process of step S81, control device 5A connected to DC/DC converter 3c may set the target value of the output power of DC/DC converter 3c to positive and negative power in accordance with the voltage variation of DC bus 10. With respect to the positive and negative powers described herein, the power flow when the power is supplied from the dc power supply 4c as a storage battery to the dc bus 10 may be positive, and the power flow when the power is supplied from the dc bus 10 to the dc power supply 4c as a storage battery may be negative. Thus, the dc power supply 4c is appropriately charged and discharged according to the voltage of the dc bus 10.
[6 ] modification example 2]
[6.1. Power System 1B ]
Fig. 12 shows a power system 1B according to a second modification. The power system 1B may include a three-phase inverter 2B, and the three-phase inverter 2B may have a control device 5B. The control device 5B may further include a storage unit 55 and a first control unit 51B in addition to the voltage measuring unit 20 and the second control unit 21.
The storage section 55 stores unique threshold voltages different from each other, which are associated with each of the plurality of DC/DC converters 3 and are equal to or higher than the threshold voltage. The intrinsic threshold voltage may be a voltage which is lower than the absolute maximum rated voltage, respectively.
The first control section 51B controls each of the plurality of DC/DC converters 3 by the control signal Ctrl _ DC/DC. When the voltage of the direct current bus 10 exceeds the threshold voltage, the first control portion 51b may reduce the output power of only a part of the plurality of DC/DC converters 3. When the voltage of the direct current bus 10 exceeds the threshold voltage, the first control portion 51B may set a time difference between the plurality of DC/DC converters 3 to decrease the output power of each DC/DC converter 3. Further, when the voltage of the DC bus 10 exceeds the threshold voltage, the first controller 51B may increase the number of DC/DC converters 3 whose output power is to be reduced, among the plurality of DC/DC converters 3, in a stepwise manner. For example, when the voltage of the direct current bus 10 exceeds any intrinsic threshold voltage, the first control section 51B may decrease the output power of the DC/DC converter 3 corresponding to the intrinsic threshold voltage. The first control portion 51B may stop each DC/DC converter 3 when the voltage of the direct current bus 10 exceeds the absolute maximum rated voltage.
According to the above power system 1B, since the first control unit 51B controls each of the plurality of DC/DC converters 3, unlike the case of the above-described embodiment in which the first control unit 51 controls only a part of the plurality of DC/DC converters 3, it is possible to perform control while adjusting the output power among the plurality of DC/DC converters 3.
Further, when the voltage of the DC bus 10 exceeds the threshold voltage, the number of DC/DC converters 3, among the plurality of DC/DC converters 3, whose output power is reduced increases stepwise, and therefore, the voltage of the DC bus 10 can be reliably suppressed to be equal to or lower than the threshold voltage.
Further, since the time difference is provided between the plurality of DC/DC converters 3 to reduce the output power of each DC/DC converter 3 when the voltage of the DC bus 10 exceeds the threshold voltage, it is possible to reliably continue the operation of the entire power system 1B while preventing the output power of all the DC/DC converters 3 from being reduced when the voltage of the DC bus 10 rises.
Further, when different inherent threshold voltages associated with each of the plurality of DC/DC converters 3 are stored, and the voltage of the direct current bus 10 exceeds any inherent threshold voltage, the output power of the DC/DC converter 3 corresponding to the inherent threshold voltage is reduced, and therefore, when the voltage of the direct current bus 10 rises, it is possible to prevent the output power of all the DC/DC converters 3 from being reduced, and reliably continue the operation of the entire power system 1B.
[6.2. actions ]
Fig. 13 shows the operation of the control device 5B. The control device 5B maintains the voltage of the dc bus 10 at the reference voltage by performing the processing of steps S31 to S41. When this operation is started, the second control unit 21 can continue to control the single-phase inverters 22. The first control unit 51B may continue to control the corresponding DC/DC converter 3. As one example, the first control portion 51B may perform MPPT (Maximum Power Point Tracking) control between the dc Power supplies 4a, 4B as the solar Power generation devices to supply the Maximum Power from the dc Power supplies 4a, 4B. The first control unit 51B may be configured to charge the dc power supply 4c as a storage battery when an excessive amount of the power supplied from the dc power supplies 4a and 4B as the solar power generation devices occurs, and to discharge the dc power supply 4c when an insufficient amount of the power is generated, in accordance with the voltage variation of the dc bus 10.
In step S31, the voltage measuring unit 20 measures the voltage of the dc bus 10.
In step S33, the second controller 21 determines whether or not the measured voltage is the reference voltage, similarly to step S13 described above. When it is determined that the measured voltage is the reference voltage (step S13; y), the process proceeds to step S31, and when it is determined that the measured voltage is not the reference voltage (step S33; n), the process proceeds to step S35.
Then, in step S35, the second controller 21 attempts to maintain the voltage of the dc bus 10 at the reference voltage by changing the control conditions of the individual single-phase inverters 22, similarly to step S15 described above.
In step S37, the voltage measuring unit 20 measures the voltage of the dc bus 10.
In step S39, the first control unit 51B determines whether or not the measured voltage exceeds any intrinsic threshold voltage. When it is determined that the measured voltage exceeds any intrinsic threshold voltage (step S39; y), the process proceeds to step S41, and when it is determined that the measured voltage does not exceed the intrinsic threshold voltage (step S39; n), the process proceeds to step S31.
Each intrinsic threshold voltage may be a single voltage value. Here, in the present embodiment, as an example, the inherent threshold voltage of the DC/DC converter 3 is set according to the maximum output power of the direct-current power supply 4 connected to the DC/DC converter 3, and for example, the inherent threshold voltage of the DC/DC converter 3 is set to be larger (or smaller) in descending order of the maximum output power of the connected direct-current power supply 4.
In step S41, the first control unit 51B reduces the output power of the DC/DC converter 3 corresponding to the specific threshold voltage lower than the measured voltage. For example, the first control unit 51B may set the output power to a power smaller than the current time. Thereby, the output power of only a part of the plurality of DC/DC converters 3 is reduced. If the process of step S41 is complete, the process may move to step S31.
Here, in the present embodiment, as an example, the specific threshold voltage of the DC/DC converter 3 is set in the order of the maximum output power of the connected direct-current power supply 4. Therefore, when the processing of steps S39 to S41 is repeated, the output power of each DC/DC converter is reduced in the order corresponding to the maximum output power of each DC power supply 4 connected to each DC/DC converter 3.
According to the above operation, when the voltage of the DC bus 10 exceeds the threshold voltage, the output powers of the DC/DC converters 3 decrease in the order corresponding to the maximum output powers of the DC power supplies 4 connected thereto. Therefore, when the output power of each DC/DC converter 3 is reduced in descending order of the maximum output power of the DC power supply 4, the amount of power supplied from the plurality of DC/DC converters 3 to the DC bus 10 can be immediately reduced significantly, and therefore, the voltage of the DC bus can be reliably suppressed to the threshold voltage or less, and safety can be improved. Further, when the output power of each DC/DC converter 3 is reduced in ascending order of the maximum output power of the DC power supply 4, the amount of power supplied from the plurality of DC/DC converters 3 to the DC bus 10 can be gradually reduced to a large extent, and therefore, the output power of the entire power system 1 can be maintained at a high level.
In the second modification, it has been described that the storage unit 55 stores unique threshold voltages different from each other in association with each of the plurality of DC/DC converters 3, and when the voltage of the DC bus 10 exceeds the unique threshold voltage, the first control unit 51B reduces the output power of the DC/DC converter 3 corresponding to the unique threshold voltage. Alternatively, it is also possible that inherent upper limit times associated with each of the plurality of DC/DC converters 3 and different from each other are stored in the storage section 55, and the first control section 51B reduces the output power of the DC/DC converter 3 corresponding to any inherent upper limit time when the duration in which the voltage of the direct current bus 10 exceeds the threshold voltage exceeds the inherent upper limit time. This makes it possible to make the upper limit time different from the other control devices 5 provided in the power system 1, and thus, the plurality of DC/DC converters 3 can be controlled based on the individual upper limit time. Therefore, when the voltage of the DC bus 10 rises, it is possible to reliably continue the operation of the entire power system 1 while preventing the output powers of all the DC/DC converters 3 from decreasing. For example, the inherent upper limit time of each DC/DC converter 3 may be set in accordance with the order corresponding to the maximum output power of the connected DC power supply 4.
Further, although it has been described that the first control unit 51B lowers the output power of each DC/DC converter 3 in the order corresponding to the maximum output power of the DC power supply 4 when the voltage of the DC bus 10 exceeds the threshold voltage, the output power of each DC/DC converter 3 may be lowered in a random order, or a history of lowering the output power of each DC/DC converter 3 may be stored, and a DC/DC converter 3 whose output power is lowered a small number of times may be preferentially set as a target of lowering. Even in these cases, when the voltage of the DC bus 10 rises, it is possible to reliably continue the operation of the entire power system 1 while preventing the output powers of all the DC/DC converters 3 from decreasing.
Further, although the case where the control device 5B includes the second control unit 21 and the storage unit 55 has been described, at least one of them may not be included. When the control device 5B does not have the second control unit 21, the second control unit 21 may be provided outside the control device 5B. In the case where the control device 5B does not have the storage unit 55, the control device 5B may reduce the output power of each DC/DC converter 3 in a random order as described above, or may reduce the output power of each DC/DC converter 3 in an order corresponding to the connection position of each DC/DC converter 3 to the rack-mounted PCS device 11.
Further, although the case where the control device 5B includes the second control unit 21 has been described, the second control unit 71 in the first modification may be included. In this case, the control device 5B may execute the processing of steps S71 to S87 instead of the processing of steps S31 to S35. Further, although the case where the control device 5B includes the first control unit 51B has been described, the first control unit 51A in the first modification may be included. In this case, when it is determined in step S39 that the measured voltage does not exceed any intrinsic threshold voltage (step S39; n), control device 5B may perform MPPT control on DC/DC converters 3a, 3B corresponding to intrinsic threshold voltages greater than the measured voltage. Further, when it is determined in step S39 that the measured voltage exceeds any intrinsic threshold voltage (step S39; y), control device 5B may perform the processing of steps S81 to S87 for DC/DC converter 3 corresponding to an intrinsic threshold voltage lower than the measured voltage.
[ 7] other modifications
In the above-described embodiment and modification, the power systems 1A and 1B have been described as including the three-phase inverter 2 having the single-phase inverter 22 for each of the U-phase, the V-phase, and the W-phase, but may include only the single-phase inverter 22, only the DC/DC converter circuit 23, and only the single-phase inverter circuit 24. Further, although the three-phase inverter 2 is described as having a single-phase inverter 22 for each phase, it is also possible to have a plurality of single-phase inverters 22 connected in series or in parallel.
Although the single-phase inverter 22 has been described as a full-bridge inverter circuit having the full-bridge circuit 241, it may be a half-bridge inverter circuit having a half-bridge circuit.
Further, although the power systems 1, 1A, 1B are described as including the dc power supply 4, the power systems 1, 1A, 1B may be externally connected to the dc power supply 4 without including the dc power supply 4.
Various embodiments of the present invention may be described with reference to flowcharts and block diagrams, where a block may indicate (1) a stage of a process of performing an operation or (2) a part of an apparatus having a function of performing an operation. Certain stages and portions may be implemented using dedicated circuitry, programmable circuitry provided in conjunction with computer-readable instructions stored on a computer-readable medium, and/or a processor provided in conjunction with computer-readable instructions stored on a computer-readable medium. The dedicated circuitry may comprise digital and/or analog hardware circuitry, and may comprise Integrated Circuits (ICs) and/or discrete circuitry. The programmable circuit may comprise a reconfigurable hardware circuit comprising memory elements such as logical AND, logical OR, logical XOR, logical NAND, logical NOR, AND other logical operations, flip-flops, registers, Field Programmable Gate Arrays (FPGAs), Programmable Logic Arrays (PLAs), AND the like.
The computer-readable medium may comprise any tangible device capable of storing instructions for execution by a suitable device, and as a result, the computer-readable medium having the instructions stored therein comprises a product including instructions which are executable to generate a means for performing operations specified in the flowchart or block diagram block or blocks. Examples of the computer readable medium include an electronic storage medium, a magnetic storage medium, an optical storage medium, an electromagnetic storage medium, a semiconductor storage medium, and the like. Other examples of the computer-readable medium include a flexible disk (registered trademark) magnetic disk, a flexible disk, a hard disk, a Random Access Memory (RAM), a Read Only Memory (ROM), an erasable programmable read only memory (EPROM or flash memory), an Electrically Erasable Programmable Read Only Memory (EEPROM), a Static Random Access Memory (SRAM), a compact disc read only memory (CD-ROM), a Digital Versatile Disk (DVD), a blu-Ray (RTM) optical disk, a memory stick, an integrated circuit card, and the like.
The computer-readable commands may comprise any one of assembly commands, Instruction Set Architecture (ISA) commands, machine dependent commands, microcode, firmware commands, state setting data, or source or object code described in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, JAVA (registered trademark), C + +, or the like, and existing program programming languages, including the "C" programming language or the same.
The computer-readable instructions are provided to a processor or programmable circuitry of a general purpose computer, special purpose computer, or other programmable data processing apparatus via a Wide Area Network (WAN), such as a local or Local Area Network (LAN), the internet, or the like, and are executed to produce a means for performing the operations specified in the flowchart or block diagram block or blocks. Examples of processors include computer processors, processing units, microprocessors, digital signal processors, controllers, microcontrollers, and the like.
FIG. 14 is an illustration of a computer 2200 that can embody various aspects of the invention in whole or in part. The program installed in the computer 2200 can function as or can execute one or more portions of an operation related to an apparatus related to an embodiment of the present invention in the computer 2200, and/or can execute a program related to an embodiment of the present invention in the computer 2200 or a stage of executing the program. Such a program can be executed by the CPU2212 by executing a part or all of the blocks in the flowcharts and block diagrams described in this specification to correspond to specific operations in the computer 2200.
The computer 2200 of the present embodiment includes a CPU2212, a RAM2214, a graphic controller 2216, and a display device 2218, which are connected to each other through a main controller 2210. The computer 2200 also includes an input/output unit such as a communication interface 2222, hard disk drive 2224, DVD-ROM drive 2226, and IC card drive, which are connected to the main controller 2210 via an input/output controller 2220. The computer also includes a legacy input/output unit such as a ROM2230 and a keyboard 2242, which is connected to the output/output controller 2220 via an input/output chip 2240.
The CPU2212 operates in accordance with programs stored in the ROM2230 and the RAM2214, thereby controlling the respective units. The graphic controller 2216 acquires the image data generated by the CPU2212 in a frame buffer or the like provided in the RAM2214 or itself, and displays the image data on the display device 2218.
Communication interface 2222 communicates with other electronic devices via a network. Hard disk drive 2224 stores programs and data used by CPU2212 within computer 2200. The DVD-ROM drive 2226 reads the program or data from the DVD-ROM2201, and supplies the program or data to the hard disk drive 2224 via the RAM 2214. The IC card driver reads and/or writes programs and data from/to the IC card.
A boot program or the like executed by the computer 2200 at the time of activation and/or a program dependent on the hardware of the computer 2200 is stored in the ROM 2230. The input/output chip 2240 may also connect various input/output units with the input/output controller 2220 via a parallel port, a serial port, a keyboard port, a mouse port, etc.
The program is provided by a computer-readable medium such as a DVD-ROM2201 or an IC card. The program is read from a computer-readable medium, which is installed in, for example, the hard disk drive 2224, the RAM2214, or the ROM2230, and executed by the CPU 2212. The information processing described in these programs is read into the computer 2200, and the programs and the various types of hardware resources described above are linked. The apparatus or method may also be configured to perform operations or processes on information in accordance with the use of the computer 2200.
For example, in the case of performing communication between the computer 2200 and an external device, the CPU2212 executes a communication program loaded into the RAM2214, and instructs the communication interface 2222 to perform communication processing based on processing described in the communication program. The communication interface 2222 reads transmission data stored in a transmission buffer processing area provided in a storage medium such as the RAM2214, the hard disk drive 2224, the DVD-ROM201, or the IC card, and transmits the read transmission data to the network, or writes reception data received by the network into a reception buffer processing area provided in the storage medium, or the like, under the control of the CPU 2212.
The CPU2212 may read all or a necessary part of a file or a database stored in an external storage medium such as the hard disk drive 2224, the DVD-ROM drive 2226(DVD-ROM2201), an IC card, or the like into the RAM2214, and perform various types of processing on data on the RAM 2214. Next, the CPU2212 writes the processed data back to the external storage medium.
Various types of information such as various types of programs, data, tables, and databases can be stored in the storage medium and subjected to information processing. The CPU2212 can perform various types of processing as follows with respect to the data read out from the RAM 2214: that is, various types of operations, information processing, condition determination, conditional branching, unconditional branching, retrieval/replacement of information, and the like, as described throughout the present disclosure, specified by a command sequence of a program, and write the result back to the RAM 2214. The CPU2212 can retrieve information of a file, a database, and the like in the storage medium. For example, in the case where the attribute values each having the first attribute associated with the attribute value of the second attribute are stored in the storage medium, the CPU2212 retrieves, from the plurality of entries, an entry in which the condition for specifying the attribute value of the first attribute coincides, reads the attribute value of the second attribute stored in the entry, and thereby acquires the attribute value of the second attribute associated with the first attribute that satisfies the preset condition.
The programs or software modules described above may be stored on computer 2200 or in a computer-readable medium near computer 2200. In addition, a storage medium such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the internet can be used as a computer-readable medium to provide the program to the computer 2200 via the network.
The present invention has been described above with reference to the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made in the above embodiments. The embodiments in which the above-described various changes and modifications are made are also included in the technical scope of the present invention, as apparent from the description of the claims.
Note that the execution order of each process such as the operation, the process, the step, and the stage in the apparatus, the system, the program, and the method shown in the claims, the description, and the drawings can be realized in any order unless "before", and the like are explicitly indicated and an output of a previous process is not used in a subsequent process. In the operational flow in the claims, the specification, and the drawings, the description is made using "first", "second", and the like for convenience of description, but the description does not necessarily mean that the operations are performed in this order.
Description of the reference symbols
1 power system, 2 three-phase inverter, 3DC/DC converter, 4 DC power supply, 5 control device, 10 DC bus, 11 device, 20 voltage measuring part, 21 second control part, 22 single-phase inverter, 23DC/DC converter circuit, 24 single-phase inverter circuit, 25 unit, 31 first positive terminal, 32 second positive terminal, 33 diode, 34 switching element, 35 switching element, 36 filter capacitor, 37 inductor, 50 voltage measuring part, 51 first control part, 52 changing part, 55 storage part, 230 transformer, 231 filter capacitor, 232 full bridge circuit, 233 positive wiring, 234 full bridge circuit, 240 filter capacitor, 241 full bridge circuit, 251 positive terminal 2200, 252 ac output terminal, 2210 computer, 2201DVD-ROM, main controller, 2212CPU, 2214RAM, graphic controller, 2218 display device, 2210 input/output controller, 2222 communication interface, 2224 hard disk drive, 2226DVD-ROM drive, 2230ROM, 2240 input/output chip, 2242 keyboard, 2301 primary coil, 2302 secondary coil, 2321 switch element, 2322 switch element, 2323 switch element, 2324 switch element, 2341 switch element, 2342 switch element, 2343 switch element, 2344 switch element, 2411 switch element, 2412 switch element, 2413 switch element, 2414 switch element.

Claims (20)

1. A control device, comprising:
a first control unit that controls at least one of a plurality of DC/DC converters provided between a DC bus maintained at a reference voltage by power exchange with an inverter and a plurality of DC power supplies that supply DC power to the DC bus, respectively; and
a voltage measuring unit for measuring the voltage of the DC bus,
the first control unit may reduce the output power of only a part of the plurality of DC/DC converters when the voltage of the DC bus exceeds a threshold voltage higher than the reference voltage.
2. The control device of claim 1,
further comprising a changing unit that changes the threshold voltage with time,
the first control unit controls any corresponding one of the plurality of DC/DC converters.
3. The control device of claim 1,
the first control unit controls any corresponding one of the plurality of DC/DC converters and reduces the output power of the corresponding DC/DC converter when the duration in which the voltage of the DC bus exceeds the threshold voltage exceeds an upper limit time,
the control device further includes a changing unit that changes the upper limit time with time.
4. A system, comprising:
an inverter that maintains a dc bus at a reference voltage through power exchange with the dc bus;
a plurality of DC/DC converters respectively provided between the direct current bus and a plurality of direct current power supplies that supply direct current to the direct current bus; and
a plurality of control devices according to any one of claims 1 to 3, which respectively control any corresponding one of the plurality of DC/DC converters.
5. The system of claim 4,
the plurality of control devices set a time difference between the plurality of DC/DC converters so as to reduce the output power of each DC/DC converter when the voltage of the direct current bus exceeds the threshold voltage.
6. The system of claim 4 or 5,
further comprising another control device having a second control unit for controlling the inverter,
the second control unit reduces the output power output from the inverter in response to receiving the command signal for limiting the output.
7. The control device of claim 1,
the first control section controls each of the plurality of DC/DC converters, and in a case where the voltage of the direct current bus exceeds the threshold voltage, the first control section sets a time difference between the plurality of DC/DC converters so as to reduce the output power of each DC/DC converter.
8. The control device according to claim 1 or 7,
the first controller controls each of the plurality of DC/DC converters, and when the voltage of the DC bus exceeds the threshold voltage, the first controller increases the number of DC/DC converters whose output power is to be reduced among the plurality of DC/DC converters in a stepwise manner.
9. The control device according to claim 7 or 8,
the first control unit decreases the output power of each DC/DC converter in an order corresponding to the maximum output power of each DC power supply connected to each DC/DC converter when the voltage of the DC bus exceeds the threshold voltage.
10. The control device according to any one of claims 7 to 9,
further comprising a storage section that stores inherent threshold voltages different from each other in association with each of the plurality of DC/DC converters and above the threshold voltage,
when the voltage of the DC bus exceeds any of the intrinsic threshold voltages, the first control unit reduces the output power of the DC/DC converter corresponding to the intrinsic threshold voltage.
11. The control device according to claim 7 or 8,
further comprising a storage section that stores inherent upper limit times associated with each of the plurality of DC/DC converters and different from each other,
when the duration in which the voltage of the direct-current bus exceeds the threshold voltage exceeds any of the inherent upper limit times, the first control unit decreases the output power of the DC/DC converter corresponding to the inherent upper limit time.
12. The control device according to claim 7 or 8,
when the voltage of the DC bus exceeds the threshold voltage, the first control unit reduces the output power of each DC/DC converter in a random order.
13. A system, comprising:
an inverter that maintains a dc bus at a reference voltage through power exchange with the dc bus;
a plurality of DC/DC converters respectively provided between the DC bus and a plurality of DC power supplies that supply DC outputs to the DC bus; and
the control device according to any one of claims 7 to 12, which controls each of the plurality of DC/DC converters.
14. The system of claim 13,
the control device further has a second control unit that controls the inverter,
the second control unit reduces the output power output from the inverter in response to receiving the command signal for limiting the output.
15. The system of claim 6 or 14,
the second control unit determines the amount of current flowing through the inverter based on a target output power included in the command signal and the voltage of the dc bus.
16. The system of any one of claims 4 to 6, 14 and 15,
at least a portion of the plurality of dc power sources is a solar power generation device,
the first control unit that controls the DC/DC converter connected to the solar power generation device may further control the solar power generation device, and the first control unit may perform MPPT control such that a maximum power is supplied from the solar power generation device when at least one of a case where the voltage of the DC bus is equal to or lower than the threshold voltage and a case where the output power of the DC/DC converter is not reduced.
17. The system according to any one of claims 4 to 6, 14 to 16,
when the output power of the part of the DC/DC inverters is reduced, the first control unit controls the output power to a target value determined in accordance with the voltage of the DC bus.
18. The system of claim 17,
when the output power of the one of the DC/DC converters is to be reduced, the first control unit cancels the control for reducing the output power, in accordance with a case where the target value is equal to or greater than at least one of the reference output power of the DC/DC converter and the reference output power of the DC power supply connected to the DC/DC converter.
19. A control method, comprising:
a control phase in which at least one of a plurality of DC/DC converters respectively provided between a direct-current bus maintained at a reference voltage by power exchange with an inverter and a plurality of direct-current power supplies that supply direct current to the direct-current bus is controlled; and
a voltage measurement step of measuring a voltage of the DC bus,
in the control phase, when the voltage of the direct current bus exceeds a threshold voltage higher than the reference voltage, the output power of only a part of the plurality of DC/DC converters is reduced.
20. A program, characterized in that,
causing a computer to:
a first control unit that controls at least one of a plurality of DC/DC converters provided between a DC bus maintained at a reference voltage by power exchange with an inverter and a plurality of DC power supplies that supply DC power to the DC bus, respectively; and
a voltage measuring unit for measuring the voltage of the DC bus,
the first control unit may reduce the output power of only a part of the plurality of DC/DC converters when the voltage of the DC bus exceeds a threshold voltage higher than the reference voltage.
CN202080023071.7A 2019-09-20 2020-08-27 Control device, system, control method, and program Pending CN113615028A (en)

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Publication number Priority date Publication date Assignee Title
CN117811398A (en) * 2024-02-27 2024-04-02 深圳通业科技股份有限公司 High-frequency auxiliary converter and control method

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JP2003339118A (en) * 2002-05-22 2003-11-28 My Way Giken Kk Distributed power supply system
JP4167215B2 (en) * 2004-10-27 2008-10-15 株式会社日立製作所 DC power distribution system control device and converter control device
JP6731607B2 (en) * 2016-03-25 2020-07-29 パナソニックＩｐマネジメント株式会社 Power conversion system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117811398A (en) * 2024-02-27 2024-04-02 深圳通业科技股份有限公司 High-frequency auxiliary converter and control method
CN117811398B (en) * 2024-02-27 2024-05-17 深圳通业科技股份有限公司 Control method of high-frequency auxiliary converter

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