WO2018179712A1 - Power conversion device, power conversion system - Google Patents

Power conversion device, power conversion system Download PDF

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Publication number
WO2018179712A1
WO2018179712A1 PCT/JP2018/001802 JP2018001802W WO2018179712A1 WO 2018179712 A1 WO2018179712 A1 WO 2018179712A1 JP 2018001802 W JP2018001802 W JP 2018001802W WO 2018179712 A1 WO2018179712 A1 WO 2018179712A1
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Prior art keywords
power
inverter
output
converter
bus
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PCT/JP2018/001802
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French (fr)
Japanese (ja)
Inventor
智規 伊藤
渉 堀尾
菊池　彰洋
藤井　裕之
賢治 花村
康太 前場
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パナソニックＩｐマネジメント株式会社
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Publication of WO2018179712A1 publication Critical patent/WO2018179712A1/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
    • 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
    • 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

Definitions

  • the present invention relates to a power conversion device and a power conversion system that convert DC power into AC power.
  • distributed power sources that are grid-connected include solar cells, fuel cells, stationary storage batteries, and in-vehicle storage batteries as power sources.
  • a typical configuration of a distributed power supply system connected to a system is a configuration in which a single distributed power supply is used to connect the system via a DC-DC converter, a DC bus and an inverter, and a plurality of distributed power supplies. Are connected to each other via each DC-DC converter, a common DC bus, and one inverter (see, for example, Patent Document 1).
  • the DC-DC converter and the inverter are physically installed in a single housing, the DC-DC converter and the inverter are controlled independently by separate control devices (for example, a microcomputer). Sometimes it is done. In such a distributed power supply system in which the DC-DC converter and the inverter are physically or controlly separated, it is necessary to make adjustments between the respective power conversion units.
  • the inverter discharge power in response to events such as system voltage rise, inverter component temperature rise, remote output command reception, and reverse power flow detection
  • a control method for suppressing the above is used.
  • the voltage of the DC bus rises immediately after starting the inverter output suppression.
  • the DC-DC converter determines from the rise in the voltage of the DC bus that the inverter is suppressing the output, and suppresses the discharge power to the DC bus so that the voltage of the DC bus does not rise above a predetermined voltage.
  • the inverter releases the output suppression when the above event is settled and a certain time has elapsed.
  • the combined power of the power stored in the DC bus and the discharge power of the DC-DC converter is input to the inverter, the output power of the inverter rises accordingly, the system voltage rises again, and again
  • a hunting phenomenon that the inverter output suppression function works will occur.
  • the hunting phenomenon leads to a lack of stability of the inverter output and also leads to a decrease in power conversion efficiency of the inverter.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a power conversion device and a power conversion system that suppress a hunting phenomenon when the output of an inverter is suppressed.
  • a power conversion device includes an inverter that converts DC power into AC power and supplies the AC power to a load or a power system, and a control circuit that controls the inverter.
  • the control circuit controls the second slope when increasing the output of the inverter by the disappearance of the output suppression reason more gently than the first slope when reducing the output of the inverter due to the occurrence of the output suppression reason. .
  • the hunting phenomenon when the output of the inverter is suppressed can be suppressed.
  • 2A and 2B are diagrams schematically illustrating the state of the voltage of the DC bus. It is a figure which shows an example of the current control at the time of the output suppression of an inverter. It is a figure which shows the application example of the current control at the time of the output suppression of an inverter.
  • FIG. 1 is a diagram for explaining a power conversion system 1 according to an embodiment of the present invention.
  • the power conversion system 1 includes a first power conversion device 10 and a second power conversion device 20.
  • the first power conversion device 10 is a power conditioner system for the solar cell 2
  • the second power conversion device 20 is a power conditioner system for the power storage unit 3.
  • FIG. 1 the example which retrofitted the power conditioner system for the electrical storage part 3 to the power conditioner system for the solar cells 2 is shown.
  • the solar cell 2 is a power generation device that directly converts light energy into electric power using the photovoltaic effect.
  • a silicon solar cell, a solar cell made of a compound semiconductor or the like, a dye-sensitized type (organic solar cell), or the like is used as the solar cell 2.
  • the solar cell 2 is connected to the first power conversion device 10 and outputs the generated power to the first power conversion device 10.
  • the first power converter 10 includes a DC-DC converter 11, a converter control circuit 12, an inverter 13, an inverter control circuit 14, and a system control circuit 15.
  • the system control circuit 15 includes a reverse flow power measurement unit 15a, a command value generation unit 15b, and a communication control unit 15c.
  • the DC-DC converter 11 and the inverter 13 are connected by a DC bus 40.
  • the converter control circuit 12 and the system control circuit 15 are connected by a communication line 41, and communication conforming to a predetermined serial communication standard (for example, RS-485 standard, TCP-IP standard) is performed between the two.
  • a predetermined serial communication standard for example, RS-485 standard, TCP-IP standard
  • the DC-DC converter 11 converts the DC power output from the solar cell 2 into DC power having a desired voltage value, and outputs the converted DC power to the DC bus 40.
  • the DC-DC converter 11 can be constituted by a step-up chopper, for example.
  • the converter control circuit 12 controls the DC-DC converter 11. As a basic control, the converter control circuit 12 performs MPPT (Maximum Power Point Tracking) control of the DC-DC converter 11 so that the output power of the solar cell 2 is maximized. Specifically, converter control circuit 12 measures the input voltage and input current of DC-DC converter 11, which are the output voltage and output current of solar cell 2, and estimates the generated power of solar cell 2. The converter control circuit 12 generates a command value for setting the generated power of the solar battery 2 to the maximum power point (optimum operating point) based on the measured output voltage of the solar battery 2 and the estimated generated power.
  • MPPT Maximum Power Point Tracking
  • the maximum power point is searched by changing the operating point voltage with a predetermined step width according to the hill-climbing method, and the command value is generated so as to maintain the maximum power point.
  • the DC-DC converter 11 performs a switching operation according to a drive signal based on the generated command value.
  • the inverter 13 is a bidirectional inverter that converts DC power input from the DC bus 40 into AC power and outputs the converted AC power to a distribution line 50 connected to a commercial power system (hereinafter simply referred to as system 4). To do. A load 5 is connected to the distribution line 50. Further, the inverter 13 converts AC power supplied from the system 4 into DC power, and outputs the converted DC power to the DC bus 40. A smoothing electrolytic capacitor (not shown) is connected to the DC bus 40.
  • the inverter control circuit 14 controls the inverter 13. As a basic control, the inverter control circuit 14 controls the inverter 13 so that the voltage of the DC bus 40 maintains the first threshold voltage. Specifically, the inverter control circuit 14 detects the voltage of the DC bus 40 and generates a command value for making the detected bus voltage coincide with the first threshold voltage. The inverter control circuit 14 generates a command value for increasing the duty ratio of the inverter 13 when the voltage of the DC bus 40 is higher than the first threshold voltage, and the inverter control circuit 14 when the voltage of the DC bus 40 is lower than the first threshold voltage. A command value for lowering the duty ratio of 13 is generated. The inverter 13 performs a switching operation according to a drive signal based on the generated command value.
  • the power storage unit 3 can charge and discharge electric power, and includes a lithium ion storage battery, a nickel hydride storage battery, a lead storage battery, an electric double layer capacitor, a lithium ion capacitor, and the like.
  • the power storage unit 3 is connected to the second power conversion device 20.
  • the second power conversion device 20 includes a DC-DC converter 21 and a converter control circuit 22.
  • the converter control circuit 22 and the system control circuit 15 of the first power conversion device 10 are connected by a communication line 42, and communication based on a predetermined serial communication standard is performed between them.
  • the DC-DC converter 21 is a bidirectional converter that is connected between the power storage unit 3 and the DC bus 40 and charges and discharges the power storage unit 3.
  • the converter control circuit 22 controls the DC-DC converter 21.
  • the converter control circuit 22 controls the DC-DC converter 21 based on the command value transmitted from the system control circuit 15 to control the power storage unit 3 at a constant current (CC) / constant voltage (CV).
  • CC constant current
  • CV constant voltage
  • Charge / discharge For example, the converter control circuit 22 receives a power command value from the system control circuit 15 at the time of discharging, and uses a value obtained by dividing the power command value by the voltage of the power storage unit 3 as a current command value. Discharge.
  • the operation display device 30 is a user interface of the first power conversion device 10 and is installed at a predetermined position in the room.
  • the operation display device 30 can be constituted by a touch panel display, for example, and provides predetermined information to the user and accepts an operation from the user.
  • the operation display device 30 and the system control circuit 15 are connected by a communication line 43, and communication based on a predetermined serial communication standard is performed between them.
  • the operation display device 30 and the system control circuit 15 may be connected wirelessly.
  • the output power of the inverter 13 needs to be suppressed.
  • the main output suppression reasons include the occurrence of reverse power flow from the inverter 13 to the grid 4, the rise of the grid voltage exceeding the set voltage, the reception of the remote output command, the temperature rise exceeding the set temperature of the components in the inverter 13, the inverter 13 An increase in power exceeding the rated power and an increase in current exceeding the rated current of the inverter 13 can be mentioned.
  • the system control circuit 15 receives an instruction related to the output power amount and output timing to the grid 4 from a grid operating organization such as a power company via an external network (for example, the Internet or a dedicated line).
  • a grid operating organization such as a power company
  • an external network for example, the Internet or a dedicated line
  • the reverse power flow measurement unit 15 a of the first power conversion device 10 detects the occurrence of reverse power flow based on the measurement value of a CT sensor (not shown) installed on the distribution line 50. .
  • the converter control circuit 22 of the second power conversion device 20 receives reverse flow detection information from the system control circuit 15 via the communication line 42.
  • the communication line 42 is often installed over the DC bus 40 that connects the first power conversion device 10 and the second power conversion device 20, and in this configuration, the communication line 42 is affected by noise from the DC bus 40. .
  • the shorter the unit period representing one bit the weaker it becomes to noise. Basically, the bit error is more likely to occur as the communication speed is increased.
  • the first power conversion device 10 detects reverse power flow, generates communication data instructing output suppression, and transmits the communication data to the second power conversion device 20 via the communication line 42, it is defined in the grid interconnection regulations.
  • the time limit 500 ms
  • the content of communication data may change during the process due to noise.
  • the inverter control circuit 14 controls the inverter 13 so that the voltage of the DC bus 40 maintains the first threshold voltage as basic control.
  • the inverter control circuit 14 executes output suppression control as priority control. Specifically, the inverter control circuit 14 controls the inverter 13 so that the output of the inverter 13 does not exceed the command value (specifically, the upper limit current value or the upper limit power value) generated by the command value generation unit 15b.
  • the bus voltage stabilization control for controlling the voltage of the DC bus 40 to be maintained at the first threshold voltage is stopped.
  • the converter control circuit 22 receives, as basic control, the amount of discharge from the power storage unit 3 to the DC-DC converter 21 or the amount of charge from the DC-DC converter 21 to the power storage unit 3 transmitted from the system control circuit 15.
  • the DC-DC converter 21 is controlled so that the command value comes.
  • the converter control circuit 22 controls the DC-DC converter 21 as priority control so that the voltage of the DC bus 40 does not exceed the second threshold voltage. This control has priority over the control for adjusting the output to the command value transmitted from the system control circuit 15.
  • the second threshold voltage is set to a value higher than the first threshold voltage.
  • the converter control circuit 12 performs MPPT control on the DC-DC converter 11 so that the output power of the solar cell 2 is maximized as basic control. Further, the converter control circuit 12 controls the DC-DC converter 11 as priority control so that the voltage of the DC bus 40 does not exceed the third threshold voltage. This control has priority over MPPT control.
  • the third threshold voltage is set to a value higher than the second threshold voltage.
  • the first threshold voltage is set to a steady voltage of the DC bus 40.
  • the first threshold voltage is set in the range of DC 280 V to 360 V, for example.
  • the second threshold voltage is set to 390V
  • the third threshold voltage is set to 410V, for example.
  • FIG. 2 (a) and 2 (b) are diagrams schematically illustrating the voltage state of the DC bus 40.
  • FIG. FIG. 2A shows the voltage state of the DC bus 40 in a steady state. The constant voltage of the DC bus 40 is maintained at the first threshold voltage by the inverter 13.
  • FIG. 2B shows the voltage state of the DC bus 40 when the output of the inverter 13 is suppressed. Normally, the voltage of the DC bus 40 during output suppression is maintained at the second threshold voltage by the DC-DC converter 21 of the power storage unit 3.
  • the inverter 13 When the output suppression of the inverter 13 is released from the state shown in FIG. 2B, the inverter 13 returns to the control for maintaining the voltage of the DC bus 40 at the first threshold voltage. Specifically, the limit value (upper limit value) of the output of the inverter 13 is returned to the rated output value of the inverter 13. In this state, unless an unexpected event occurs, the output of the inverter 13 does not reach the limit value, and only the voltage stabilization control of the DC bus 40 is activated.
  • the inverter 13 When the output suppression of the inverter 13 is released, the inverter 13 tries to discharge the electric charge accumulated in the electrolytic capacitor at the same time in order to reduce the voltage of the DC bus 40 from the second threshold voltage to the first threshold voltage. As a result, the output power of the inverter 13 increases, an output suppression event occurs again, and the voltage of the DC bus 40 increases again. Thereafter, when the reason for suppressing the output disappears, the inverter 13 again releases the electric charge accumulated in the electrolytic capacitor, and the output power of the inverter 13 increases. That is, a hunting phenomenon occurs.
  • the first inclination when the output of the inverter 13 is decreased due to the generation of the output suppression reason is controlled so as to become gentler.
  • FIG. 3 is a diagram illustrating an example of current control when the output of the inverter 13 is suppressed.
  • the limit value (upper limit value) of the suppression current of the inverter 13 is set to the rated output current value of the inverter 13 in a steady state. That is, even if the voltage of the DC bus 40 increases due to a sudden event during normal operation, the output current of the inverter 13 is set to stop increasing at the rated output current value.
  • the inverter control circuit 14 decreases the output of the inverter 13 with the first slope S1.
  • the first slope S1 is defined by a suppression amount [A / ms] per unit time.
  • the first slope S1 is set so that the time from when the inverter 13 starts suppression during discharge at the rated output value to when the suppression is completed falls within the standard value.
  • the power storage unit 3 discharges 2.0 kW, and the inverter 13 supplies 5.5 kW to the load 5.
  • the load 5 is disconnected from this state and the power consumption of the load 5 becomes 0.0 W, the 5.5 kW output power of the inverter 13 flows backward to the grid 4.
  • the reverse power flow is not stopped within 500 ms, the inverter 13 must be disconnected from the system 4, and the power generation of the solar cell 2 is stopped during the disconnection, resulting in an economic loss.
  • the grid interconnection regulations can be satisfied, and the inverter 13 need not be disconnected. .
  • the amount of suppression [A / ms] per unit time is calculated by dividing the difference between the rated output value of the inverter 13 and the target power value by the time for completing the suppression. For example, in the case of output suppression by a remote output command, the time to complete the suppression is on the order of seconds or minutes, and the first slope S1 becomes gentle compared to the case of output suppression due to the occurrence of reverse power flow.
  • the output of the inverter 13 may be suppressed by a current value or may be suppressed by a power value.
  • the current value it is possible to suppress overcurrent due to excessive output at the time of release of suppression.
  • the power value the output can be accurately suppressed even when the system voltage changes.
  • the system voltage may change according to output suppression such as suppression when the system voltage rises.
  • the output of the inverter 13 may be suppressed by both the current value and the power value.
  • the inverter control circuit 14 increases the output of the inverter 13 with the second slope S2.
  • the second slope S2 is defined by the suppression release amount [A / ms] per unit time.
  • the second slope S2 is set more gently than the first slope S1.
  • the second slope S2 is determined based on the rated output value of the inverter 13 and the rated output value of the DC-DC converter 21, for example.
  • the inverter 13 when the rated output power value of the inverter 13 is 5 kW and the rated output power value of the DC-DC converter 21 is 3 kW, only the DC-DC converter 21 is discharging at the rated output value (the inverter 13 is outputting at 3 kW).
  • the DC-DC converter 21 is discharged again at the rated output value, and the inverter 13 is connected to the DC bus 40 according to the discharge power of the DC-DC converter 21.
  • the electric charge accumulated in the electrolytic capacitor is discharged.
  • the inverter 13 discharges a maximum of 5 kW immediately after the suppression is released.
  • the output power of the inverter 13 becomes excessive with respect to the output power of the DC-DC converter 21.
  • the second slope S2 is set in consideration of this excessive electric energy. Specifically, the second slope S2 is set so that the suppression release time becomes longer as the excessive amount of power increases.
  • the suppression release time is the time from when the suppression release is started until the limiter value of the output current or output power of the inverter 13 is restored to the limiter value at the steady state. Thereby, the output power of the inverter 13 can be discharged so that the output suppression function is not activated again.
  • the second slope S2 may be determined in consideration of the difference between the first threshold voltage and the second threshold voltage and the capacitance of the electrolytic capacitor.
  • the second slope S2 may be determined based on the difference between the voltage of the DC bus 40 when the inverter 13 starts output suppression and the voltage of the DC bus 40 when the inverter 13 cancels output suppression. As the difference is larger, the second slope S2 is set more gently.
  • FIG. 4 is a diagram showing an application example of current control when the output of the inverter 13 is suppressed.
  • the first slope S1 and / or the second slope S2 shown in FIG. 3 may be variably designed (see S1, S1a, S1b, S2, S2a, S2b).
  • the suppression speed can be delayed or the suppression release speed can be increased according to the state of the system 4 or the load 5.
  • the suppression release speed can be increased for the system 4 having a larger capacity.
  • the suppression release speed can be increased as the power consumption of the load 5 increases. Conversely, when the capacity of the system 4 is small or when the power consumption of the load 5 is small, it is necessary to slow down the suppression release speed.
  • the first slope S1 and / or the second slope S2 may be changed according to the type of the output suppression reason. For example, when the reason for output suppression is temperature rise or system voltage rise, immediate output suppression and output suppression release are not required. On the other hand, as described above, when reverse power flow occurs, immediate output suppression is required. Further, when the output is suppressed due to the power failure of the grid 4, after the recovery from the power failure, the immediate output suppression release is requested according to the FRT (Fault Ride Through) requirement defined by the grid interconnection regulations. As described above, the required return time period differs depending on the cause of the suppression start. However, by making the first slope S1 and / or the second slope S2 variable, it is possible to cope flexibly.
  • FRT ault Ride Through
  • the output of the inverter 13 becomes excessive when the output suppression is canceled, and the hunting phenomenon is suppressed again. Can be suppressed.
  • the first slope S1 is set to a value that can suppress the rated output value of the inverter 13 to a predetermined power value within a predetermined time. Thereby, for example, when a remote output command is received, power suppression that satisfies the command can be quickly performed. In addition, even when a reverse power flow occurs due to the opening of the load 5 or the like, it is possible to suppress power within a time limit that complies with the grid connection regulations.
  • the second slope S2 is set based on the rated output value of the DC-DC converter 21.
  • the output current or output power of the DC-DC converter 21 is specified using communication. There is a need.
  • the output suppression of the inverter 13 is canceled, the output of the inverter 13 becomes excessive when the voltage of the DC bus 40 is greatly deviated upward from the target value (first threshold voltage). In other words, since the maximum voltage is discharged so that the voltage of the DC bus 40 becomes the target value, the output of the inverter 13 becomes excessive.
  • the second slope S2 is determined based on the difference between the voltage of the DC bus 40 when the inverter 13 starts suppressing the output and the voltage of the DC bus 40 when releasing the output suppression, the inverter 13 is connected to the DC bus 40. Even if there are a plurality of DC-DC converters or the DC-DC converter 21 is separated from the inverter 13, the power can be controlled independently on the inverter 13 side.
  • the inverter control circuit 14 and the system control circuit 15 are depicted separately, but each may be realized by a separate microcomputer or may be realized by a single microcomputer.
  • the example in which the first power conversion device 10 and the second power conversion device 20 are installed in different cases has been described.
  • a configuration example in which the system control circuit 15 and the converter control circuit 22 are connected by the communication line 42 while the first power conversion device 10 and the second power conversion device 20 are installed in one housing is also an example of the present invention. It is included in the embodiment.
  • the solar cell 2 is connected to the first power conversion device 10 .
  • another power generation device using renewable energy such as a wind power generation device or a micro hydraulic power generation device, may be connected.
  • the power converter (10) characterized by controlling the 2nd inclination at the time of making loose. According to this, it is possible to suppress a hunting phenomenon in which the output becomes excessive when the suppression of the inverter (13) is released and is suppressed again.
  • the DC side of the inverter (13) is connected via a DC bus (40) to a DC-DC converter (21) that controls the output of a predetermined DC power supply (3).
  • the power converter (10) according to item 1 or 2 wherein the second slope is determined based on a rated output of the DC-DC converter (21) and a rated output of the inverter (13). ).
  • the DC side of the inverter (13) is connected via a DC bus (40) to a DC-DC converter (21) that controls the output of a predetermined DC power supply (3).
  • the inverter (13) and the DC-DC converter (21) are installed in separate housings,
  • the second slope includes the voltage of the DC bus (40) when the inverter (13) starts output suppression and the voltage of the DC bus (40) when the inverter (13) ends output suppression.
  • control circuit (14, 15) changes at least one of the value of the first inclination and the value of the second inclination in accordance with the type of the output suppression reason.
  • Conversion device (10) According to this, flexible output suppression control according to the kind of output suppression reason is attained.
  • the present invention can be used for a distributed power supply system in which a solar battery and a stationary storage battery are combined.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

A power conversion device 10 in which an inverter 13 converts direct-current power to alternating-current power and supplies the alternating-current power to a load 5 or a system 4. Control circuits 14, 15 control the inverter 13. The control circuits 14, 15 more strictly control a first slope that is for decreasing the output of the inverter 13 because of a reason for output suppression than a second slope that is for increasing the output of the inverter 13 because of the expiration of a reason for output suppression.

Description

電力変換装置、電力変換システムPower conversion device, power conversion system
　本発明は、直流電力を交流電力に変換する電力変換装置、電力変換システムに関する。 The present invention relates to a power conversion device and a power conversion system that convert DC power into AC power.
　現在、系統連系される分散型電源には、電源ソースとして太陽電池、燃料電池、定置型蓄電池、車載蓄電池などがある。系統に連系する分散型電源システムの代表的な構成として、単一の分散型電源を使用してＤＣ－ＤＣコンバータ、直流バス及びインバータを介して系統連系する構成と、複数の分散型電源を使用してそれぞれのＤＣ－ＤＣコンバータ、共通の直流バス及び１つのインバータを介して系統連系する構成がある（例えば、特許文献１参照）。 Currently, distributed power sources that are grid-connected include solar cells, fuel cells, stationary storage batteries, and in-vehicle storage batteries as power sources. A typical configuration of a distributed power supply system connected to a system is a configuration in which a single distributed power supply is used to connect the system via a DC-DC converter, a DC bus and an inverter, and a plurality of distributed power supplies. Are connected to each other via each DC-DC converter, a common DC bus, and one inverter (see, for example, Patent Document 1).
　後者において、複数のＤＣ－ＤＣコンバータと１つのインバータが１つの筐体内に設置される構成と、少なくとも１つのＤＣ－ＤＣコンバータと１つのインバータが分離された筐体内に設置される構成がある。 In the latter, there are a configuration in which a plurality of DC-DC converters and one inverter are installed in one casing, and a configuration in which at least one DC-DC converter and one inverter are installed in a separate casing.
　また、物理的に１つの筐体内にＤＣ－ＤＣコンバータとインバータが設置される構成であっても、制御的にはＤＣ－ＤＣコンバータとインバータが別々の制御装置(例えば、マイコン)により独立に制御されることもある。このようなＤＣ－ＤＣコンバータとインバータが物理的もしくは制御的に分離された分散型電源システムでは、それぞれの電力変換部間の調整を行う必要がある。 Even if the DC-DC converter and the inverter are physically installed in a single housing, the DC-DC converter and the inverter are controlled independently by separate control devices (for example, a microcomputer). Sometimes it is done. In such a distributed power supply system in which the DC-DC converter and the inverter are physically or controlly separated, it is necessary to make adjustments between the respective power conversion units.
　例えば、太陽電池と定置型蓄電池を組み合わせた分散型電源システムにおいて、系統電圧の上昇、インバータ部品温度の上昇、遠隔出力指令の受信、逆潮流電力の検出などの事象に対して、インバータの放電電力を抑制する制御方式が用いられる場合がある。この制御方式では、インバータの出力抑制を開始した直後、直流バスの電圧が上昇する。ＤＣ－ＤＣコンバータは直流バスの電圧上昇から、インバータが出力抑制中であると判断し、直流バスの電圧が所定の電圧以上に上昇しないように、直流バスへの放電電力を抑制する。 For example, in a distributed power system that combines solar cells and stationary storage batteries, the inverter discharge power in response to events such as system voltage rise, inverter component temperature rise, remote output command reception, and reverse power flow detection In some cases, a control method for suppressing the above is used. In this control method, the voltage of the DC bus rises immediately after starting the inverter output suppression. The DC-DC converter determines from the rise in the voltage of the DC bus that the inverter is suppressing the output, and suppresses the discharge power to the DC bus so that the voltage of the DC bus does not rise above a predetermined voltage.
特開２０１５－１２２９０６号公報JP2015-122906A
　上記の制御方式では、上記事象が収まり一定時間が経過すると、インバータは出力抑制を解除する。しかしながら解除直後に、直流バスに蓄えられていた電力と、ＤＣ－ＤＣコンバータの放電電力の合成電力がインバータに入力され、それに応じてインバータの出力電力が上昇し、再び系統電圧が上昇し、再びインバータ出力の抑制機能が働くというハンチング現象が発生する可能性がある。ハンチング現象は、インバータ出力の安定性欠如に繋がり、インバータの電力変換効率の低下にも繋がる。 In the above control method, the inverter releases the output suppression when the above event is settled and a certain time has elapsed. However, immediately after the release, the combined power of the power stored in the DC bus and the discharge power of the DC-DC converter is input to the inverter, the output power of the inverter rises accordingly, the system voltage rises again, and again There is a possibility that a hunting phenomenon that the inverter output suppression function works will occur. The hunting phenomenon leads to a lack of stability of the inverter output and also leads to a decrease in power conversion efficiency of the inverter.
　本発明はこうした状況に鑑みなされたものであり、その目的は、インバータの出力抑制時のハンチング現象を抑制する電力変換装置、電力変換システムを提供することにある。 The present invention has been made in view of such circumstances, and an object thereof is to provide a power conversion device and a power conversion system that suppress a hunting phenomenon when the output of an inverter is suppressed.
　上記課題を解決するために、本発明のある態様の電力変換装置は、直流電力を交流電力に変換し、当該交流電力を負荷または電力系統へ供給するインバータと、前記インバータを制御する制御回路と、を備える。前記制御回路は、出力抑制事由の発生により前記インバータの出力を低下させる際の第１の傾きより、前記出力抑制事由の消滅により前記インバータの出力を上昇させる際の第２の傾きを緩く制御する。 In order to solve the above problem, a power conversion device according to an aspect of the present invention includes an inverter that converts DC power into AC power and supplies the AC power to a load or a power system, and a control circuit that controls the inverter. . The control circuit controls the second slope when increasing the output of the inverter by the disappearance of the output suppression reason more gently than the first slope when reducing the output of the inverter due to the occurrence of the output suppression reason. .
　本発明によれば、インバータの出力抑制時のハンチング現象を抑制することができる。 According to the present invention, the hunting phenomenon when the output of the inverter is suppressed can be suppressed.
本発明の実施の形態に係る電力変換システムを説明するための図である。It is a figure for demonstrating the power conversion system which concerns on embodiment of this invention. 図２（ａ）、（ｂ）は、直流バスの電圧の状態を模式的に描いた図である。2A and 2B are diagrams schematically illustrating the state of the voltage of the DC bus. インバータの出力抑制時の電流制御の一例を示す図である。It is a figure which shows an example of the current control at the time of the output suppression of an inverter. インバータの出力抑制時の電流制御の応用例を示す図である。It is a figure which shows the application example of the current control at the time of the output suppression of an inverter.
　図１は、本発明の実施の形態に係る電力変換システム１を説明するための図である。電力変換システム１は、第１電力変換装置１０及び第２電力変換装置２０を備える。第１電力変換装置１０は太陽電池２用のパワーコンディショナシステムであり、第２電力変換装置２０は蓄電部３用のパワーコンディショナシステムである。図１では、太陽電池２用のパワーコンディショナシステムに、蓄電部３用のパワーコンディショナシステムを後付けした例を示している。 FIG. 1 is a diagram for explaining a power conversion system 1 according to an embodiment of the present invention. The power conversion system 1 includes a first power conversion device 10 and a second power conversion device 20. The first power conversion device 10 is a power conditioner system for the solar cell 2, and the second power conversion device 20 is a power conditioner system for the power storage unit 3. In FIG. 1, the example which retrofitted the power conditioner system for the electrical storage part 3 to the power conditioner system for the solar cells 2 is shown.
　太陽電池２は、光起電力効果を利用し、光エネルギーを直接電力に変換する発電装置である。太陽電池２として、シリコン太陽電池、化合物半導体などを素材にした太陽電池、色素増感型（有機太陽電池）等が使用される。太陽電池２は第１電力変換装置１０と接続され、発電した電力を第１電力変換装置１０に出力する。 The solar cell 2 is a power generation device that directly converts light energy into electric power using the photovoltaic effect. As the solar cell 2, a silicon solar cell, a solar cell made of a compound semiconductor or the like, a dye-sensitized type (organic solar cell), or the like is used. The solar cell 2 is connected to the first power conversion device 10 and outputs the generated power to the first power conversion device 10.
　第１電力変換装置１０は、ＤＣ－ＤＣコンバータ１１、コンバータ制御回路１２、インバータ１３、インバータ制御回路１４、及びシステム制御回路１５を備える。システム制御回路１５は、逆潮流電力計測部１５ａ、指令値生成部１５ｂ、及び通信制御部１５ｃを含む。ＤＣ－ＤＣコンバータ１１とインバータ１３間は直流バス４０で接続される。コンバータ制御回路１２とシステム制御回路１５間は通信線４１で接続され、両者の間で所定のシリアル通信規格（例えば、例えばＲＳ－４８５規格、ＴＣＰ－ＩＰ規格）に準拠した通信が行われる。 The first power converter 10 includes a DC-DC converter 11, a converter control circuit 12, an inverter 13, an inverter control circuit 14, and a system control circuit 15. The system control circuit 15 includes a reverse flow power measurement unit 15a, a command value generation unit 15b, and a communication control unit 15c. The DC-DC converter 11 and the inverter 13 are connected by a DC bus 40. The converter control circuit 12 and the system control circuit 15 are connected by a communication line 41, and communication conforming to a predetermined serial communication standard (for example, RS-485 standard, TCP-IP standard) is performed between the two.
　ＤＣ－ＤＣコンバータ１１は、太陽電池２から出力される直流電力を、所望の電圧値の直流電力に変換し、変換した直流電力を直流バス４０に出力する。ＤＣ－ＤＣコンバータ１１は例えば、昇圧チョッパで構成することができる。 The DC-DC converter 11 converts the DC power output from the solar cell 2 into DC power having a desired voltage value, and outputs the converted DC power to the DC bus 40. The DC-DC converter 11 can be constituted by a step-up chopper, for example.
　コンバータ制御回路１２はＤＣ－ＤＣコンバータ１１を制御する。コンバータ制御回路１２は基本制御として、太陽電池２の出力電力が最大になるようＤＣ－ＤＣコンバータ１１をＭＰＰＴ(Maximum Power Point Tracking) 制御する。具体的にはコンバータ制御回路１２は、太陽電池２の出力電圧および出力電流である、ＤＣ－ＤＣコンバータ１１の入力電圧および入力電流を計測して太陽電池２の発電電力を推定する。コンバータ制御回路１２は、計測した太陽電池２の出力電圧と推定した発電電力をもとに、太陽電池２の発電電力を最大電力点（最適動作点）にするための指令値を生成する。例えば、山登り法に従い動作点電圧を所定のステップ幅で変化させて最大電力点を探索し、最大電力点を維持するように指令値を生成する。ＤＣ－ＤＣコンバータ１１は、生成された指令値に基づく駆動信号に応じてスイッチング動作する。 The converter control circuit 12 controls the DC-DC converter 11. As a basic control, the converter control circuit 12 performs MPPT (Maximum Power Point Tracking) control of the DC-DC converter 11 so that the output power of the solar cell 2 is maximized. Specifically, converter control circuit 12 measures the input voltage and input current of DC-DC converter 11, which are the output voltage and output current of solar cell 2, and estimates the generated power of solar cell 2. The converter control circuit 12 generates a command value for setting the generated power of the solar battery 2 to the maximum power point (optimum operating point) based on the measured output voltage of the solar battery 2 and the estimated generated power. For example, the maximum power point is searched by changing the operating point voltage with a predetermined step width according to the hill-climbing method, and the command value is generated so as to maintain the maximum power point. The DC-DC converter 11 performs a switching operation according to a drive signal based on the generated command value.
　インバータ１３は双方向インバータであり、直流バス４０から入力される直流電力を交流電力に変換し、変換した交流電力を商用電力系統（以下、単に系統４という）に接続された配電線５０に出力する。当該配電線５０には負荷５が接続される。またインバータ１３は、系統４から供給される交流電力を直流電力に変換し、変換した直流電力を直流バス４０に出力する。直流バス４０には、平滑用の電解コンデンサ（不図示）が接続されている。 The inverter 13 is a bidirectional inverter that converts DC power input from the DC bus 40 into AC power and outputs the converted AC power to a distribution line 50 connected to a commercial power system (hereinafter simply referred to as system 4). To do. A load 5 is connected to the distribution line 50. Further, the inverter 13 converts AC power supplied from the system 4 into DC power, and outputs the converted DC power to the DC bus 40. A smoothing electrolytic capacitor (not shown) is connected to the DC bus 40.
　インバータ制御回路１４はインバータ１３を制御する。インバータ制御回路１４は基本制御として、直流バス４０の電圧が第１閾値電圧を維持するようにインバータ１３を制御する。具体的にはインバータ制御回路１４は、直流バス４０の電圧を検出し、検出したバス電圧を第１閾値電圧に一致させるための指令値を生成する。インバータ制御回路１４は、直流バス４０の電圧が第１閾値電圧より高い場合はインバータ１３のデューティ比を上げるための指令値を生成し、直流バス４０の電圧が第１閾値電圧より低い場合はインバータ１３のデューティ比を下げるための指令値を生成する。インバータ１３は、生成された指令値に基づく駆動信号に応じてスイッチング動作する。 The inverter control circuit 14 controls the inverter 13. As a basic control, the inverter control circuit 14 controls the inverter 13 so that the voltage of the DC bus 40 maintains the first threshold voltage. Specifically, the inverter control circuit 14 detects the voltage of the DC bus 40 and generates a command value for making the detected bus voltage coincide with the first threshold voltage. The inverter control circuit 14 generates a command value for increasing the duty ratio of the inverter 13 when the voltage of the DC bus 40 is higher than the first threshold voltage, and the inverter control circuit 14 when the voltage of the DC bus 40 is lower than the first threshold voltage. A command value for lowering the duty ratio of 13 is generated. The inverter 13 performs a switching operation according to a drive signal based on the generated command value.
　蓄電部３は、電力を充放電可能であり、リチウムイオン蓄電池、ニッケル水素蓄電池、鉛蓄電池、電気二重層キャパシタ、リチウムイオンキャパシタ等を含む。蓄電部３は第２電力変換装置２０と接続される。 The power storage unit 3 can charge and discharge electric power, and includes a lithium ion storage battery, a nickel hydride storage battery, a lead storage battery, an electric double layer capacitor, a lithium ion capacitor, and the like. The power storage unit 3 is connected to the second power conversion device 20.
　第２電力変換装置２０は、ＤＣ－ＤＣコンバータ２１及びコンバータ制御回路２２を備える。コンバータ制御回路２２と、第１電力変換装置１０のシステム制御回路１５は通信線４２で接続され、両者の間で所定のシリアル通信規格に準拠した通信が行われる。 The second power conversion device 20 includes a DC-DC converter 21 and a converter control circuit 22. The converter control circuit 22 and the system control circuit 15 of the first power conversion device 10 are connected by a communication line 42, and communication based on a predetermined serial communication standard is performed between them.
　ＤＣ－ＤＣコンバータ２１は、蓄電部３と直流バス４０の間に接続され、蓄電部３を充放電する双方向コンバータである。コンバータ制御回路２２はＤＣ－ＤＣコンバータ２１を制御する。コンバータ制御回路２２は基本制御として、システム制御回路１５から送信されてくる指令値をもとにＤＣ－ＤＣコンバータ２１を制御して、蓄電部３を定電流（ＣＣ）／定電圧（ＣＶ）で充電／放電する。例えばコンバータ制御回路２２は、放電時においてシステム制御回路１５から電力指令値を受信し、当該電力指令値を蓄電部３の電圧で割った値を電流指令値として、ＤＣ－ＤＣコンバータ２１に定電流放電させる。 The DC-DC converter 21 is a bidirectional converter that is connected between the power storage unit 3 and the DC bus 40 and charges and discharges the power storage unit 3. The converter control circuit 22 controls the DC-DC converter 21. As a basic control, the converter control circuit 22 controls the DC-DC converter 21 based on the command value transmitted from the system control circuit 15 to control the power storage unit 3 at a constant current (CC) / constant voltage (CV). Charge / discharge. For example, the converter control circuit 22 receives a power command value from the system control circuit 15 at the time of discharging, and uses a value obtained by dividing the power command value by the voltage of the power storage unit 3 as a current command value. Discharge.
　操作表示装置３０は、第１電力変換装置１０のユーザインターフェイスであり、室内の所定の位置に設置される。操作表示装置３０は例えば、タッチパネルディスプレイで構成することができ、ユーザに所定の情報を提供すると共に、ユーザからの操作を受け付ける。操作表示装置３０とシステム制御回路１５は通信線４３で接続され、両者の間で所定のシリアル通信規格に準拠した通信が行われる。なお操作表示装置３０とシステム制御回路１５の間は無線で接続されてもよい。 The operation display device 30 is a user interface of the first power conversion device 10 and is installed at a predetermined position in the room. The operation display device 30 can be constituted by a touch panel display, for example, and provides predetermined information to the user and accepts an operation from the user. The operation display device 30 and the system control circuit 15 are connected by a communication line 43, and communication based on a predetermined serial communication standard is performed between them. The operation display device 30 and the system control circuit 15 may be connected wirelessly.
　以上の回路構成において、インバータ１３の出力電力を抑制する必要がある場合が発生する。主な出力抑制事由として、インバータ１３から系統４への逆潮流の発生、系統電圧の設定電圧を超える上昇、遠隔出力指令の受信、インバータ１３内の部品の設定温度を超える温度上昇、インバータ１３の定格電力を超える電力上昇、インバータ１３の定格電流を超える電流上昇が挙げられる。 In the above circuit configuration, the output power of the inverter 13 needs to be suppressed. The main output suppression reasons include the occurrence of reverse power flow from the inverter 13 to the grid 4, the rise of the grid voltage exceeding the set voltage, the reception of the remote output command, the temperature rise exceeding the set temperature of the components in the inverter 13, the inverter 13 An increase in power exceeding the rated power and an increase in current exceeding the rated current of the inverter 13 can be mentioned.
　蓄電部３からの放電中に、日射変動により太陽電池２の発電量が増加した場合、又は負荷５の消費電力が低下した場合、系統４への逆潮流電力が発生し、売電状態になることがある。日本では系統連系規程により蓄電システムから、蓄電池の定格容量の５％以上の電力を５００ｍｓを超えて系統４へ逆潮流することが禁止されている。従って、蓄電部３が接続された電力変換システム１において逆潮流が検出された場合、５００ｍｓ以内に逆潮流を抑える必要がある。 When the amount of power generated by the solar cell 2 increases due to fluctuations in solar radiation or when the power consumption of the load 5 decreases during discharge from the power storage unit 3, reverse power flow to the grid 4 is generated and the power is sold. Sometimes. In Japan, the grid connection regulations prohibit the reverse flow of power from the power storage system to the grid 4 for more than 5% of the rated capacity of the storage battery over 500 ms. Therefore, when a reverse power flow is detected in the power conversion system 1 to which the power storage unit 3 is connected, it is necessary to suppress the reverse power flow within 500 ms.
　また日本では２０１５年１月の再生可能エネルギー固定価格買取制度の改正により、新たに系統に連系する太陽光発電と風力発電の設備に遠隔出力制御システムの導入が義務付けられている。システム制御回路１５は、電力会社などの系統運用機関から外部ネットワーク（例えば、インターネット又は専用線）を介して、系統４への出力電力量と出力タイミングに関する指示を受信する。 In Japan, the revision of the renewable energy feed-in tariff system in January 2015 has made it mandatory to introduce a remote output control system for solar and wind power generation facilities that are newly connected to the grid. The system control circuit 15 receives an instruction related to the output power amount and output timing to the grid 4 from a grid operating organization such as a power company via an external network (for example, the Internet or a dedicated line).
　インバータ１３の出力電力を抑制する方法として、太陽電池２のＤＣ－ＤＣコンバータ１１の出力電力を抑制する方法、蓄電部３のＤＣ－ＤＣコンバータ２１の出力電力を抑制する方法、インバータ１３の出力電力を抑制する方法がある。太陽電池２のＤＣ－ＤＣコンバータ１１の出力電力を抑制する方法は、太陽電池２の発電量を無駄にすることに繋がる。従って太陽電池２のＤＣ－ＤＣコンバータ１１の出力抑制は最後に実行すべき制御である。 As a method of suppressing the output power of the inverter 13, a method of suppressing the output power of the DC-DC converter 11 of the solar cell 2, a method of suppressing the output power of the DC-DC converter 21 of the power storage unit 3, and the output power of the inverter 13 There is a way to suppress this. The method of suppressing the output power of the DC-DC converter 11 of the solar cell 2 leads to wasted power generation amount of the solar cell 2. Therefore, the output suppression of the DC-DC converter 11 of the solar cell 2 is the control to be executed last.
　逆潮流が検出された場合、蓄電部３からの放電を停止すればよいため、蓄電部３のＤＣ－ＤＣコンバータ２１の出力電力を抑制する方法が最も直截的な制御である。しかしながら、第２電力変換装置２０が第１電力変換装置１０から分離され、系統４から離れた位置に設置されている場合、逆潮流の検出から蓄電部３のＤＣ－ＤＣコンバータ２１の出力抑制までにタイムラグが発生しやすくなる。 When the reverse power flow is detected, it is only necessary to stop the discharge from the power storage unit 3, so the method for suppressing the output power of the DC-DC converter 21 of the power storage unit 3 is the most straightforward control. However, when the second power conversion device 20 is separated from the first power conversion device 10 and installed at a position away from the grid 4, from detection of reverse power flow to output suppression of the DC-DC converter 21 of the power storage unit 3. Time lag is likely to occur.
　図１に示した構成では、第１電力変換装置１０の逆潮流電力計測部１５ａが、配電線５０に設置されたＣＴセンサ（不図示）の計測値をもとに逆潮流の発生を検出する。第２電力変換装置２０のコンバータ制御回路２２は、システム制御回路１５から通信線４２を介して逆潮流の検出情報を受信する。通信線４２は、第１電力変換装置１０と第２電力変換装置２０を繋ぐ直流バス４０に這わせて設置されることが多く、この構成では通信線４２は直流バス４０からノイズの影響を受ける。また二値の電圧を使用したデジタル通信では、１ビットを表す単位期間を短くするほどノイズに弱くなる性質があり、基本的に通信速度を上げるほどビット誤りが発生しやすくなる。 In the configuration shown in FIG. 1, the reverse power flow measurement unit 15 a of the first power conversion device 10 detects the occurrence of reverse power flow based on the measurement value of a CT sensor (not shown) installed on the distribution line 50. . The converter control circuit 22 of the second power conversion device 20 receives reverse flow detection information from the system control circuit 15 via the communication line 42. The communication line 42 is often installed over the DC bus 40 that connects the first power conversion device 10 and the second power conversion device 20, and in this configuration, the communication line 42 is affected by noise from the DC bus 40. . In digital communication using a binary voltage, the shorter the unit period representing one bit, the weaker it becomes to noise. Basically, the bit error is more likely to occur as the communication speed is increased.
　従って第１電力変換装置１０が逆潮流を検出し、出力抑制を指示する通信データを生成し、通信線４２を介して第２電力変換装置２０に送信する方法では、系統連系規程に定められる時限（５００ｍｓ）を遵守できない可能性がある。またノイズにより通信データの内容が途中で変わってしまう可能性もある。 Therefore, in the method in which the first power conversion device 10 detects reverse power flow, generates communication data instructing output suppression, and transmits the communication data to the second power conversion device 20 via the communication line 42, it is defined in the grid interconnection regulations. There is a possibility that the time limit (500 ms) cannot be observed. In addition, the content of communication data may change during the process due to noise.
　そこで先にインバータ１３の出力電力を抑制し、後から蓄電部３のＤＣ－ＤＣコンバータ２１の出力電力を抑制する方法が考えられる。上述のようにインバータ制御回路１４は基本制御として、直流バス４０の電圧が第１閾値電圧を維持するようにインバータ１３を制御する。出力抑制をすべき場合は、インバータ制御回路１４は優先制御として、出力抑制制御を実行する。具体的にはインバータ制御回路１４は、インバータ１３の出力が指令値生成部１５ｂにより生成された指令値（具体的には上限電流値または上限電力値）を超えないようにインバータ１３を制御する。出力抑制中は、直流バス４０の電圧を第１閾値電圧に維持するように制御するバス電圧の安定化制御は停止する。 Therefore, a method is conceivable in which the output power of the inverter 13 is first suppressed and the output power of the DC-DC converter 21 of the power storage unit 3 is subsequently suppressed. As described above, the inverter control circuit 14 controls the inverter 13 so that the voltage of the DC bus 40 maintains the first threshold voltage as basic control. When output suppression is to be performed, the inverter control circuit 14 executes output suppression control as priority control. Specifically, the inverter control circuit 14 controls the inverter 13 so that the output of the inverter 13 does not exceed the command value (specifically, the upper limit current value or the upper limit power value) generated by the command value generation unit 15b. During the output suppression, the bus voltage stabilization control for controlling the voltage of the DC bus 40 to be maintained at the first threshold voltage is stopped.
　インバータ１３の出力抑制が開始した時点では、太陽電池２のＤＣ－ＤＣコンバータ１１及び／又は蓄電部３のＤＣ－ＤＣコンバータ２１の出力抑制は開始していない。従ってインバータ１３の出力電力に対してインバータ１３の入力電力が過多となり、直流バス４０の電圧が上昇する。より具体的には直流バス４０に接続された電解コンデンサに電荷が蓄積されていく。 At the time when output suppression of the inverter 13 is started, output suppression of the DC-DC converter 11 of the solar cell 2 and / or the DC-DC converter 21 of the power storage unit 3 is not started. Therefore, the input power of the inverter 13 becomes excessive with respect to the output power of the inverter 13, and the voltage of the DC bus 40 increases. More specifically, electric charges are accumulated in the electrolytic capacitor connected to the DC bus 40.
　上述のようにコンバータ制御回路２２は基本制御として、蓄電部３からＤＣ－ＤＣコンバータ２１への放電量またはＤＣ－ＤＣコンバータ２１から蓄電部３への充電量が、システム制御回路１５から送信されてくる指令値になるようにＤＣ－ＤＣコンバータ２１を制御する。さらにコンバータ制御回路２２は優先制御として、直流バス４０の電圧が第２閾値電圧を超えないようにＤＣ－ＤＣコンバータ２１を制御する。この制御は、システム制御回路１５から送信されてくる指令値に出力を合わせる制御に対して優先する。第２閾値電圧は第１閾値電圧より高い値に設定される。 As described above, the converter control circuit 22 receives, as basic control, the amount of discharge from the power storage unit 3 to the DC-DC converter 21 or the amount of charge from the DC-DC converter 21 to the power storage unit 3 transmitted from the system control circuit 15. The DC-DC converter 21 is controlled so that the command value comes. Furthermore, the converter control circuit 22 controls the DC-DC converter 21 as priority control so that the voltage of the DC bus 40 does not exceed the second threshold voltage. This control has priority over the control for adjusting the output to the command value transmitted from the system control circuit 15. The second threshold voltage is set to a value higher than the first threshold voltage.
　上述のようにコンバータ制御回路１２は基本制御として、太陽電池２の出力電力が最大になるようＤＣ－ＤＣコンバータ１１をＭＰＰＴ制御する。さらにコンバータ制御回路１２は優先制御として、直流バス４０の電圧が第３閾値電圧を超えないようにＤＣ－ＤＣコンバータ１１を制御する。この制御は、ＭＰＰＴ制御に対して優先する。第３閾値電圧は第２閾値電圧より高い値に設定される。 As described above, the converter control circuit 12 performs MPPT control on the DC-DC converter 11 so that the output power of the solar cell 2 is maximized as basic control. Further, the converter control circuit 12 controls the DC-DC converter 11 as priority control so that the voltage of the DC bus 40 does not exceed the third threshold voltage. This control has priority over MPPT control. The third threshold voltage is set to a value higher than the second threshold voltage.
　第１閾値電圧は、直流バス４０の定常時の電圧に設定される。系統電圧がＡＣ２００Ｖの場合、第１閾値電圧は例えば、ＤＣ２８０Ｖ～３６０Ｖの範囲に設定される。第２閾値電圧は例えば３９０Ｖ、第３閾値電圧は例えば４１０Ｖに設定される。インバータ１３の出力抑制により直流バス４０の電圧が上昇し、直流バス４０の電圧が第２閾値電圧に到達すると蓄電部３のＤＣ－ＤＣコンバータ２１によるバス電圧の上昇抑制制御が発動する。直流バス４０の電圧上昇のエネルギーが、蓄電部３のＤＣ－ＤＣコンバータ２１による上昇抑制エネルギーより大きい場合は、直流バス４０の電圧がさらに上昇する。直流バス４０の電圧が第３閾値電圧に到達すると太陽電池２のＤＣ－ＤＣコンバータ１１によるバス電圧の上昇抑制制御が発動する。 The first threshold voltage is set to a steady voltage of the DC bus 40. When the system voltage is 200 V AC, the first threshold voltage is set in the range of DC 280 V to 360 V, for example. For example, the second threshold voltage is set to 390V, and the third threshold voltage is set to 410V, for example. When the output of the inverter 13 is suppressed, the voltage of the DC bus 40 increases, and when the voltage of the DC bus 40 reaches the second threshold voltage, the bus voltage increase suppression control by the DC-DC converter 21 of the power storage unit 3 is activated. When the energy for increasing the voltage of the DC bus 40 is larger than the energy for suppressing the increase by the DC-DC converter 21 of the power storage unit 3, the voltage of the DC bus 40 further increases. When the voltage of the DC bus 40 reaches the third threshold voltage, the bus voltage rise suppression control by the DC-DC converter 11 of the solar cell 2 is activated.
　図２（ａ）、（ｂ）は、直流バス４０の電圧の状態を模式的に描いた図である。図２（ａ）は、定常時の直流バス４０の電圧の状態を示している。定常時の直流バス４０の電圧は、インバータ１３により第１閾値電圧に維持される。図２（ｂ）は、インバータ１３の出力抑制時の直流バス４０の電圧の状態を示している。通常、出力抑制中の直流バス４０の電圧は、蓄電部３のＤＣ－ＤＣコンバータ２１により第２閾値電圧に維持される。 2 (a) and 2 (b) are diagrams schematically illustrating the voltage state of the DC bus 40. FIG. FIG. 2A shows the voltage state of the DC bus 40 in a steady state. The constant voltage of the DC bus 40 is maintained at the first threshold voltage by the inverter 13. FIG. 2B shows the voltage state of the DC bus 40 when the output of the inverter 13 is suppressed. Normally, the voltage of the DC bus 40 during output suppression is maintained at the second threshold voltage by the DC-DC converter 21 of the power storage unit 3.
　図２（ｂ）に示す状態からインバータ１３の出力抑制が解除されると、インバータ１３は直流バス４０の電圧を第１閾値電圧に維持する制御に復帰する。具体的にはインバータ１３の出力のリミット値（上限値）が、インバータ１３の定格出力値に戻される。この状態では、突発的な事由が発生しない限り、インバータ１３の出力がリミット値に到達することはなく、直流バス４０の電圧安定化制御のみが働く状態になる。 When the output suppression of the inverter 13 is released from the state shown in FIG. 2B, the inverter 13 returns to the control for maintaining the voltage of the DC bus 40 at the first threshold voltage. Specifically, the limit value (upper limit value) of the output of the inverter 13 is returned to the rated output value of the inverter 13. In this state, unless an unexpected event occurs, the output of the inverter 13 does not reach the limit value, and only the voltage stabilization control of the DC bus 40 is activated.
　インバータ１３の出力抑制が解除されると、インバータ１３は直流バス４０の電圧を、第２閾値電圧から第１閾値電圧に低下させるために電解コンデンサに蓄積された電荷をいっきに放出しようとする。これにより、インバータ１３の出力電力が上昇し、再び出力抑制事由が発生し、再び直流バス４０の電圧が上昇する。その後、出力抑制事由が消滅すると、インバータ１３は再び電解コンデンサに蓄積された電荷をいっきに放出し、インバータ１３の出力電力が上昇する。即ち、ハンチング現象が発生する。 When the output suppression of the inverter 13 is released, the inverter 13 tries to discharge the electric charge accumulated in the electrolytic capacitor at the same time in order to reduce the voltage of the DC bus 40 from the second threshold voltage to the first threshold voltage. As a result, the output power of the inverter 13 increases, an output suppression event occurs again, and the voltage of the DC bus 40 increases again. Thereafter, when the reason for suppressing the output disappears, the inverter 13 again releases the electric charge accumulated in the electrolytic capacitor, and the output power of the inverter 13 increases. That is, a hunting phenomenon occurs.
　このハンチング現象を抑制するために本実施の形態では、出力抑制事由の発生によりインバータ１３の出力を低下させる際の第１の傾きより、当該出力抑制事由の消滅によりインバータ１３の出力を上昇させる際の第２の傾きの方が緩くなるように制御する。 In order to suppress the hunting phenomenon, in the present embodiment, when the output of the inverter 13 is increased by the disappearance of the output suppression reason, the first inclination when the output of the inverter 13 is decreased due to the generation of the output suppression reason. The second inclination is controlled so as to become gentler.
　図３は、インバータ１３の出力抑制時の電流制御の一例を示す図である。図３に示す例では、インバータ１３の抑制電流のリミット値（上限値）は定常時において、インバータ１３の定格出力電流値に設定されている。即ち、定常時に突発的な事由により直流バス４０の電圧が上昇しても、インバータ１３の出力電流は定格出力電流値で上昇が止まるように設定されている。 FIG. 3 is a diagram illustrating an example of current control when the output of the inverter 13 is suppressed. In the example shown in FIG. 3, the limit value (upper limit value) of the suppression current of the inverter 13 is set to the rated output current value of the inverter 13 in a steady state. That is, even if the voltage of the DC bus 40 increases due to a sudden event during normal operation, the output current of the inverter 13 is set to stop increasing at the rated output current value.
　出力抑制事由が発生すると、インバータ制御回路１４はインバータ１３の出力を第１の傾きＳ１で低下させる。第１の傾きＳ１は、単位時間あたりの抑制量［Ａ／ｍｓ］で規定される。第１の傾きＳ１は例えば、インバータ１３が定格出力値で放電中に抑制を開始してから抑制が完了するまでの時間が、規格値に収まるように設定される。 When an output suppression event occurs, the inverter control circuit 14 decreases the output of the inverter 13 with the first slope S1. The first slope S1 is defined by a suppression amount [A / ms] per unit time. For example, the first slope S1 is set so that the time from when the inverter 13 starts suppression during discharge at the rated output value to when the suppression is completed falls within the standard value.
　例えば、太陽電池２が３．５ｋＷを発電し、蓄電部３が２．０ｋＷを放電し、インバータ１３が５．５ｋＷを負荷５に供給している状態を考える。この状態から負荷５が解列され、負荷５の消費電力が０．０Ｗになった場合、インバータ１３の５．５ｋＷの出力電力が系統４に逆潮流される。この場合、５００ｍｓ以内に逆潮流を止めなければ、インバータ１３を系統４から解列しなければならず、解列中は太陽電池２の発電が停止するため経済的損失となる。この例において、第１の傾きＳ１を０．０１１（＝５．５／５００）［ｋＷ／ｍｓ］に設定すれば、系統連系規程を満たすことができ、インバータ１３を解列せずに済む。 For example, consider a state where the solar cell 2 generates 3.5 kW, the power storage unit 3 discharges 2.0 kW, and the inverter 13 supplies 5.5 kW to the load 5. When the load 5 is disconnected from this state and the power consumption of the load 5 becomes 0.0 W, the 5.5 kW output power of the inverter 13 flows backward to the grid 4. In this case, if the reverse power flow is not stopped within 500 ms, the inverter 13 must be disconnected from the system 4, and the power generation of the solar cell 2 is stopped during the disconnection, resulting in an economic loss. In this example, if the first slope S1 is set to 0.011 (= 5.5 / 500) [kW / ms], the grid interconnection regulations can be satisfied, and the inverter 13 need not be disconnected. .
　なお、逆潮流の発生以外の出力抑制事由の場合、必ずしも系統４への出力電力を０．０Ｗまで低下させる必要がない場合もある。その場合、インバータ１３の定格出力値と目標電力値との差分を、抑制を完了させる時間で割ることにより、単位時間あたりの抑制量［Ａ／ｍｓ］を算出する。例えば、遠隔出力指令による出力抑制の場合、抑制を完了させる時間は秒オーダ又は分オーダとなり、逆潮流発生による出力抑制の場合と比較して、第１の傾きＳ１は緩くなる。 In addition, in the case of an output suppression reason other than the occurrence of reverse power flow, it may not always be necessary to reduce the output power to the grid 4 to 0.0 W. In this case, the amount of suppression [A / ms] per unit time is calculated by dividing the difference between the rated output value of the inverter 13 and the target power value by the time for completing the suppression. For example, in the case of output suppression by a remote output command, the time to complete the suppression is on the order of seconds or minutes, and the first slope S1 becomes gentle compared to the case of output suppression due to the occurrence of reverse power flow.
　なお、インバータ１３の出力は電流値で抑制してもよいし、電力値で抑制してもよい。電流値を使用する場合、抑制解除時の出力過多による過電流を抑制することができる。電力値を使用する場合、系統電圧が変化した場合でも正確に出力抑制を行うことができる。例えば、系統電圧上昇時の抑制など、出力抑制に応じて系統電圧が変化してしまうことがある。なお、インバータ１３の出力を電流値と電力値の両方で抑制してもよい。 Note that the output of the inverter 13 may be suppressed by a current value or may be suppressed by a power value. When using the current value, it is possible to suppress overcurrent due to excessive output at the time of release of suppression. When the power value is used, the output can be accurately suppressed even when the system voltage changes. For example, the system voltage may change according to output suppression such as suppression when the system voltage rises. Note that the output of the inverter 13 may be suppressed by both the current value and the power value.
　出力抑制事由が消滅すると、インバータ制御回路１４はインバータ１３の出力を第２の傾きＳ２で上昇させる。第２の傾きＳ２は、単位時間あたりの抑制解除量［Ａ／ｍｓ］で規定される。第２の傾きＳ２は、第１の傾きＳ１より緩やかに設定される。第２の傾きＳ２は例えば、インバータ１３の定格出力値及びＤＣ－ＤＣコンバータ２１の定格出力値にもとづき決定される。 When the output suppression reason disappears, the inverter control circuit 14 increases the output of the inverter 13 with the second slope S2. The second slope S2 is defined by the suppression release amount [A / ms] per unit time. The second slope S2 is set more gently than the first slope S1. The second slope S2 is determined based on the rated output value of the inverter 13 and the rated output value of the DC-DC converter 21, for example.
　例えば、インバータ１３の定格出力電力値が５ｋＷ、ＤＣ－ＤＣコンバータ２１の定格出力電力値が３ｋＷの場合において、ＤＣ－ＤＣコンバータ２１のみが定格出力値で放電中（インバータ１３は３ｋＷで出力中）に抑制が開始された場合を考える。なお太陽電池２は発電を停止しているとする。この状態でインバータ１３の出力抑制が解除されると、ＤＣ－ＤＣコンバータ２１は再び定格出力値で放電し、インバータ１３はＤＣ－ＤＣコンバータ２１の放電電力に合わせて、直流バス４０に接続された電解コンデンサに蓄積された電荷を放電する。これにより、インバータ１３は抑制解除直後に最大５ｋＷを放電する。 For example, when the rated output power value of the inverter 13 is 5 kW and the rated output power value of the DC-DC converter 21 is 3 kW, only the DC-DC converter 21 is discharging at the rated output value (the inverter 13 is outputting at 3 kW). Let us consider a case where suppression is started. It is assumed that the solar cell 2 has stopped power generation. When the output suppression of the inverter 13 is released in this state, the DC-DC converter 21 is discharged again at the rated output value, and the inverter 13 is connected to the DC bus 40 according to the discharge power of the DC-DC converter 21. The electric charge accumulated in the electrolytic capacitor is discharged. Thus, the inverter 13 discharges a maximum of 5 kW immediately after the suppression is released.
　このように、インバータ１３の出力抑制解除の直後は、ＤＣ－ＤＣコンバータ２１の出力電力に対してインバータ１３の出力電力が過大になる。上記の例では２．０ｋＷ（＝５ｋＷ－３ｋＷ）過大になる。第２の傾きＳ２は、この過大となる電力量を考慮して設定される。具体的には第２の傾きＳ２は、過大となる電力量が大きいほど抑制解除時間が長くなるように設定される。抑制解除時間は抑制解除を開始してから、インバータ１３の出力電流または出力電力のリミッタ値を定常時のリミッタ値に復帰させるまでの時間である。これにより、インバータ１３の出力電力を、再び出力抑制機能が発動しないように放電することができる。 As described above, immediately after the output suppression of the inverter 13 is released, the output power of the inverter 13 becomes excessive with respect to the output power of the DC-DC converter 21. In the above example, 2.0 kW (= 5 kW-3 kW) is excessive. The second slope S2 is set in consideration of this excessive electric energy. Specifically, the second slope S2 is set so that the suppression release time becomes longer as the excessive amount of power increases. The suppression release time is the time from when the suppression release is started until the limiter value of the output current or output power of the inverter 13 is restored to the limiter value at the steady state. Thereby, the output power of the inverter 13 can be discharged so that the output suppression function is not activated again.
　なお、実際に過大となる電力量は、第１閾値電圧と第２閾値電圧の差分と電解コンデンサの容量に依存する。従って第２の傾きＳ２を、第１閾値電圧と第２閾値電圧の差分と電解コンデンサの容量を考慮して決定してもよい。また第２の傾きＳ２を、インバータ１３が出力抑制を開始する際の直流バス４０の電圧と、インバータ１３が出力抑制を解除する際の直流バス４０の電圧の差分に基づき決定してもよい。当該差分が大きいほど第２の傾きＳ２を緩く設定する。 Note that the amount of power that actually becomes excessive depends on the difference between the first threshold voltage and the second threshold voltage and the capacitance of the electrolytic capacitor. Therefore, the second slope S2 may be determined in consideration of the difference between the first threshold voltage and the second threshold voltage and the capacitance of the electrolytic capacitor. The second slope S2 may be determined based on the difference between the voltage of the DC bus 40 when the inverter 13 starts output suppression and the voltage of the DC bus 40 when the inverter 13 cancels output suppression. As the difference is larger, the second slope S2 is set more gently.
　図４は、インバータ１３の出力抑制時の電流制御の応用例を示す図である。図４に示すように、図３に示した第１の傾きＳ１及び／又は第２の傾きＳ２は可変に設計されてもよい（Ｓ１、Ｓ１ａ、Ｓ１ｂ、Ｓ２、Ｓ２ａ、Ｓ２ｂ参照）。第１の傾きＳ１及び／又は第２の傾きＳ２を可変とすることで、系統４または負荷５の状況に応じて抑制速度を遅めたり、抑制解除速度を速めたりすることができる。例えば、容量の大きい系統４ほど抑制解除速度を速めることができる。また負荷５の消費電力が大きいほど抑制解除速度を速めることができる。反対に系統４の容量が小さい場合、または負荷５の消費電力が小さい場合、抑制解除速度を遅くする必要がある。 FIG. 4 is a diagram showing an application example of current control when the output of the inverter 13 is suppressed. As shown in FIG. 4, the first slope S1 and / or the second slope S2 shown in FIG. 3 may be variably designed (see S1, S1a, S1b, S2, S2a, S2b). By making the first slope S1 and / or the second slope S2 variable, the suppression speed can be delayed or the suppression release speed can be increased according to the state of the system 4 or the load 5. For example, the suppression release speed can be increased for the system 4 having a larger capacity. Further, the suppression release speed can be increased as the power consumption of the load 5 increases. Conversely, when the capacity of the system 4 is small or when the power consumption of the load 5 is small, it is necessary to slow down the suppression release speed.
　また、出力抑制事由の種別に応じて、第１の傾きＳ１及び／又は第２の傾きＳ２を変えてもよい。例えば、出力抑制事由が温度上昇や系統電圧上昇の場合、即時的な出力抑制および出力抑制解除は要求されない。これに対して上述したように逆潮流発生の場合、即時的な出力抑制が要求される。また系統４の停電により出力抑制していた場合、停電復帰後は、系統連系規程により定められたＦＲＴ（Fault Ride Through）要件により、即時的な出力抑制解除が要求される。このように抑制開始の要因に対して要求復帰時限が異なるが、第１の傾きＳ１及び／又は第２の傾きＳ２を可変にすることにより、柔軟に対応することができる。 Further, the first slope S1 and / or the second slope S2 may be changed according to the type of the output suppression reason. For example, when the reason for output suppression is temperature rise or system voltage rise, immediate output suppression and output suppression release are not required. On the other hand, as described above, when reverse power flow occurs, immediate output suppression is required. Further, when the output is suppressed due to the power failure of the grid 4, after the recovery from the power failure, the immediate output suppression release is requested according to the FRT (Fault Ride Through) requirement defined by the grid interconnection regulations. As described above, the required return time period differs depending on the cause of the suppression start. However, by making the first slope S1 and / or the second slope S2 variable, it is possible to cope flexibly.
　以上説明したように本実施の形態によれば、第２の傾きＳ２を第１の傾きＳ１より緩く設定することにより、出力抑制解除時にインバータ１３の出力が過大となり、再度抑制されてしまうハンチング現象を抑えることができる。 As described above, according to the present embodiment, by setting the second slope S2 to be looser than the first slope S1, the output of the inverter 13 becomes excessive when the output suppression is canceled, and the hunting phenomenon is suppressed again. Can be suppressed.
　第１の傾きＳ１は、インバータ１３の定格出力値を、所定の時間内に所定の電力値まで抑制できる値に設定される。これにより、例えば遠隔出力指令を受信した際、速やかに指令を満足する電力抑制を行うことができる。また、負荷５の開放などにより逆潮流が発生した際にも、系統連系規程に適合する時限内に電力抑制を行うことができる。 The first slope S1 is set to a value that can suppress the rated output value of the inverter 13 to a predetermined power value within a predetermined time. Thereby, for example, when a remote output command is received, power suppression that satisfies the command can be quickly performed. In addition, even when a reverse power flow occurs due to the opening of the load 5 or the like, it is possible to suppress power within a time limit that complies with the grid connection regulations.
　第２の傾きＳ２は、ＤＣ－ＤＣコンバータ２１の定格出力値に基づいて設定される。ＤＣ－ＤＣコンバータ２１から直流バス４０に出力される電力が過大であるほど、抑制解除時に出力過多となる可能性が高くなる。従ってＤＣ－ＤＣコンバータ２１が出力する電力に応じて、インバータ１３は出力抑制を解除すればよい。 The second slope S2 is set based on the rated output value of the DC-DC converter 21. The more power that is output from the DC-DC converter 21 to the DC bus 40, the higher the possibility of excessive output at the time of release of suppression. Therefore, the inverter 13 may cancel the output suppression according to the power output from the DC-DC converter 21.
　本実施の形態のように第１電力変換装置１０と第２電力変換装置２０が別筐体に設置されている場合、ＤＣ－ＤＣコンバータ２１の出力電流または出力電力を、通信を用いて指定する必要がある。インバータ１３の出力抑制を解除する際にインバータ１３の出力が過大になるのは、直流バス４０の電圧が目標値（第１閾値電圧）に対して、大きく上方に乖離している場合である。言い換えると、直流バス４０の電圧が目標値となるように最大限放電してしまうため、インバータ１３の出力が過大になる。インバータ１３が出力抑制を開始する際の直流バス４０の電圧と、出力抑制を解除する際の直流バス４０の電圧との差分に基づき第２の傾きＳ２を決定すれば、直流バス４０に接続されるＤＣ－ＤＣコンバータが複数であったり、ＤＣ－ＤＣコンバータ２１がインバータ１３から分離されていても、インバータ１３側で独立して電力を制御することができる。 When the first power converter 10 and the second power converter 20 are installed in separate housings as in the present embodiment, the output current or output power of the DC-DC converter 21 is specified using communication. There is a need. When the output suppression of the inverter 13 is canceled, the output of the inverter 13 becomes excessive when the voltage of the DC bus 40 is greatly deviated upward from the target value (first threshold voltage). In other words, since the maximum voltage is discharged so that the voltage of the DC bus 40 becomes the target value, the output of the inverter 13 becomes excessive. If the second slope S2 is determined based on the difference between the voltage of the DC bus 40 when the inverter 13 starts suppressing the output and the voltage of the DC bus 40 when releasing the output suppression, the inverter 13 is connected to the DC bus 40. Even if there are a plurality of DC-DC converters or the DC-DC converter 21 is separated from the inverter 13, the power can be controlled independently on the inverter 13 side.
　以上、本発明を実施の形態をもとに説明した。実施の形態は例示であり、それらの各構成要素や各処理プロセスの組み合わせにいろいろな変形例が可能なこと、またそうした変形例も本発明の範囲にあることは当業者に理解されるところである。 The present invention has been described based on the embodiments. The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. .
　図１では、インバータ制御回路１４とシステム制御回路１５を分離して描いているが、それぞれが別のマイクロコンピュータで実現されてもよいし、１つのマイクロコンピュータで実現されてもよい。また上述の実施の形態では、第１電力変換装置１０と第２電力変換装置２０が別の筐体に設置される例を説明した。この点、第１電力変換装置１０と第２電力変換装置２０が１つの筐体に設置されつつ、システム制御回路１５とコンバータ制御回路２２が通信線４２で接続される構成例も本発明の一実施の形態に含まれる。 In FIG. 1, the inverter control circuit 14 and the system control circuit 15 are depicted separately, but each may be realized by a separate microcomputer or may be realized by a single microcomputer. Moreover, in the above-described embodiment, the example in which the first power conversion device 10 and the second power conversion device 20 are installed in different cases has been described. In this regard, a configuration example in which the system control circuit 15 and the converter control circuit 22 are connected by the communication line 42 while the first power conversion device 10 and the second power conversion device 20 are installed in one housing is also an example of the present invention. It is included in the embodiment.
　また上記実施の形態では、第１電力変換装置１０に太陽電池２が接続される例を説明した。この点、太陽電池２の代わりに、風力発電装置、マイクロ水力発電装置など、再生可能エネルギーを用いた他の発電装置が接続されてもよい。 In the above embodiment, an example in which the solar cell 2 is connected to the first power conversion device 10 has been described. In this respect, instead of the solar battery 2, another power generation device using renewable energy, such as a wind power generation device or a micro hydraulic power generation device, may be connected.
　なお、実施の形態は、以下の項目によって特定されてもよい。 Note that the embodiment may be specified by the following items.
［項目１］
　直流電力を交流電力に変換し、当該交流電力を負荷（５）または電力系統（４）へ供給するインバータ（１３）と、
　前記インバータ（１３）を制御する制御回路（１４、１５）と、を備え、
　前記制御回路（１４、１５）は、出力抑制事由の発生により前記インバータ（１３）の出力を低下させる際の第１の傾きより、前記出力抑制事由の消滅により前記インバータ（１３）の出力を上昇させる際の第２の傾きを緩く制御することを特徴とする電力変換装置（１０）。
　これによれば、インバータ（１３）の抑制解除時に出力が過大となり、再度抑制されてしまうハンチング現象を抑制することができる。
［項目２］
　前記第１の傾きは、前記インバータ（１３）の定格出力と、出力抑制を完了させるべき時限に基づき決定されることを特徴とする項目１に記載の電力変換装置（１０）。
　これによれば、系統連系規程により要求される規則を遵守することができる。
［項目３］
　前記インバータ（１３）の直流側は直流バス（４０）を介して、所定の直流電源（３）の出力を制御するＤＣ－ＤＣコンバータ（２１）に接続されており、
　前記第２の傾きは、前記ＤＣ－ＤＣコンバータ（２１）の定格出力と、前記インバータ（１３）の定格出力に基づき決定されることを特徴とする項目１または２の記載の電力変換装置（１０）。
　これによれば、インバータ（１３）の抑制解除時に出力が過大となり、再度抑制されてしまうことを防止することができる。
［項目４］
　前記インバータ（１３）の直流側は直流バス（４０）を介して、所定の直流電源（３）の出力を制御するＤＣ－ＤＣコンバータ（２１）に接続されており、
　前記インバータ（１３）と前記ＤＣ－ＤＣコンバータ（２１）は別々の筐体に設置されており、
　前記第２の傾きは、前記インバータ（１３）が出力抑制を開始する際の前記直流バス（４０）の電圧と、前記インバータ（１３）が出力抑制を終了する際の前記直流バス（４０）の電圧との差分に基づき決定されることを特徴とした項目１または２に記載の電力変換装置（１０）。
　これによれば、インバータ（１３）の抑制解除時に出力が過大となり、再度抑制されてしまうことを防止することができる。
［項目５］
　前記制御回路（１４、１５）は、出力抑制事由が発生したとき前記インバータ（１４）の出力電流または出力電力を抑制することを特徴とする項目１から４のいずれかに記載の電力変換装置（１０）。
　これによれば、過電流または過電力を防止することができる。
［項目６］
　前記制御回路（１４、１５）は、前記第１の傾きの値および前記第２の傾きの値の少なくとも一方を変更可能であることを特徴とする項目１から５のいずれかに記載の電力変換装置（１０）。
　これによれば、状況に応じて柔軟な出力抑制制御が可能となる。
［項目７］
　前記制御回路（１４、１５）は、出力抑制事由の種類に応じて、前記第１の傾きの値および前記第２の傾きの値の少なくとも一方を変えることを特徴とする項目６に記載の電力変換装置（１０）。
　これによれば、出力抑制事由の種類に応じた柔軟な出力抑制制御が可能となる。
［項目８］
　直流バス（４０）から供給される直流電力を交流電力に変換し、当該交流電力を負荷（５）または電力系統（４）へ供給するインバータ（１３）と、
　前記インバータ（１３）を制御する制御回路（１４、１５）と、
　所定の直流電源（３）の出力を制御し、当該出力を前記直流バス（４０）に供給するＤＣ－ＤＣコンバータ（２１）と、を備え、
　前記制御回路（１４、１５）は、出力抑制事由の発生により前記インバータ（１３）の出力を低下させる際の第１の傾きより、前記出力抑制事由の消滅により前記インバータ（１３）の出力を上昇させる際の第２の傾きを緩く制御することを特徴とする電力変換システム（１）。
　これによれば、インバータ（１３）の抑制解除時に出力が過大となり、再度抑制されてしまうハンチング現象を抑制することができる。 [Item 1]
An inverter (13) for converting DC power to AC power and supplying the AC power to the load (5) or the power system (4);
A control circuit (14, 15) for controlling the inverter (13),
The control circuit (14, 15) increases the output of the inverter (13) due to the disappearance of the output suppression reason from the first slope when the output of the inverter (13) is decreased due to the occurrence of the output suppression reason. The power converter (10) characterized by controlling the 2nd inclination at the time of making loose.
According to this, it is possible to suppress a hunting phenomenon in which the output becomes excessive when the suppression of the inverter (13) is released and is suppressed again.
[Item 2]
The power conversion device (10) according to item 1, wherein the first inclination is determined based on a rated output of the inverter (13) and a time limit for completing output suppression.
According to this, the rules required by the grid interconnection regulations can be observed.
[Item 3]
The DC side of the inverter (13) is connected via a DC bus (40) to a DC-DC converter (21) that controls the output of a predetermined DC power supply (3).
The power converter (10) according to item 1 or 2, wherein the second slope is determined based on a rated output of the DC-DC converter (21) and a rated output of the inverter (13). ).
According to this, it is possible to prevent the output from becoming excessive when the inverter (13) is released from being suppressed and being suppressed again.
[Item 4]
The DC side of the inverter (13) is connected via a DC bus (40) to a DC-DC converter (21) that controls the output of a predetermined DC power supply (3).
The inverter (13) and the DC-DC converter (21) are installed in separate housings,
The second slope includes the voltage of the DC bus (40) when the inverter (13) starts output suppression and the voltage of the DC bus (40) when the inverter (13) ends output suppression. 3. The power conversion device (10) according to item 1 or 2, wherein the power conversion device (10) is determined based on a difference from a voltage.
According to this, it is possible to prevent the output from becoming excessive when the inverter (13) is released from being suppressed and being suppressed again.
[Item 5]
5. The power conversion device according to claim 1, wherein the control circuit (14, 15) suppresses an output current or output power of the inverter (14) when an output suppression event occurs. 10).
According to this, overcurrent or overpower can be prevented.
[Item 6]
The power conversion according to any one of items 1 to 5, wherein the control circuit (14, 15) is capable of changing at least one of the value of the first inclination and the value of the second inclination. Device (10).
This makes it possible to perform flexible output suppression control according to the situation.
[Item 7]
Item 7. The power according to Item 6, wherein the control circuit (14, 15) changes at least one of the value of the first inclination and the value of the second inclination in accordance with the type of the output suppression reason. Conversion device (10).
According to this, flexible output suppression control according to the kind of output suppression reason is attained.
[Item 8]
An inverter (13) for converting DC power supplied from the DC bus (40) into AC power and supplying the AC power to the load (5) or the power system (4);
Control circuits (14, 15) for controlling the inverter (13);
A DC-DC converter (21) for controlling an output of a predetermined DC power source (3) and supplying the output to the DC bus (40),
The control circuit (14, 15) increases the output of the inverter (13) due to the disappearance of the output suppression reason from the first slope when the output of the inverter (13) is decreased due to the occurrence of the output suppression reason. A power conversion system (1) characterized in that the second inclination at the time of control is controlled loosely.
According to this, it is possible to suppress a hunting phenomenon in which the output becomes excessive when the suppression of the inverter (13) is released and is suppressed again.
　１　電力変換システム、　２　太陽電池、　３　蓄電部、　４　系統、　５　負荷、　１０　第１電力変換装置、　１１　ＤＣ－ＤＣコンバータ、　１２　コンバータ制御回路、　１３　インバータ、　１４　インバータ制御回路、　１５　システム制御回路、　１５ａ　逆潮流電力計測部、　１５ｂ　指令値生成部、　１５ｃ　通信制御部、　２０　第２電力変換装置、　２１　ＤＣ－ＤＣコンバータ、　２２　コンバータ制御回路、　３０　操作表示装置、　４０　直流バス、　４１，４２，４３　通信線、　５０　配電線。 DESCRIPTION OF SYMBOLS 1 Power conversion system, 2 Solar cell, 3 Power storage part, 4 system | strain, 5 load, 10 1st power converter, 11 DC-DC converter, 12 Converter control circuit, 13 inverter, 14 inverter control circuit, 15 system control circuit, 15a Reverse power flow measurement unit, 15b Command value generation unit, 15c Communication control unit, 20 Second power conversion device, 21 DC-DC converter, 22 Converter control circuit, 30 Operation display device, 40 DC bus, 41, 42, 43 Communication line, 50 distribution lines.
　本発明は、太陽電池と定置型蓄電池を組み合わせた分散型電源システムに利用可能である。 The present invention can be used for a distributed power supply system in which a solar battery and a stationary storage battery are combined.

Claims (8)

  1. 　直流電力を交流電力に変換し、当該交流電力を負荷または電力系統へ供給するインバータと、
    　前記インバータを制御する制御回路と、を備え、
    　前記制御回路は、出力抑制事由の発生により前記インバータの出力を低下させる際の第１の傾きより、前記出力抑制事由の消滅により前記インバータの出力を上昇させる際の第２の傾きを緩く制御することを特徴とする電力変換装置。     An inverter that converts DC power to AC power and supplies the AC power to a load or power system;
    A control circuit for controlling the inverter,
    The control circuit controls the second slope when increasing the output of the inverter by the disappearance of the output suppression reason more gently than the first slope when reducing the output of the inverter due to the occurrence of the output suppression reason. The power converter characterized by the above-mentioned.
  2. 　前記第１の傾きは、前記インバータの定格出力と、出力抑制を完了させるべき時限に基づき決定されることを特徴とする請求項１に記載の電力変換装置。 The power conversion device according to claim 1, wherein the first inclination is determined based on a rated output of the inverter and a time limit for completing output suppression.
  3. 　前記インバータの直流側は直流バスを介して、所定の直流電源の出力を制御するＤＣ－ＤＣコンバータに接続されており、
    　前記第２の傾きは、前記ＤＣ－ＤＣコンバータの定格出力と、前記インバータの定格出力に基づき決定されることを特徴とする請求項１または２の記載の電力変換装置。     The DC side of the inverter is connected via a DC bus to a DC-DC converter that controls the output of a predetermined DC power source,
    3. The power converter according to claim 1, wherein the second slope is determined based on a rated output of the DC-DC converter and a rated output of the inverter.
  4. 　前記インバータの直流側は直流バスを介して、所定の直流電源の出力を制御するＤＣ－ＤＣコンバータに接続されており、
    　前記インバータと前記ＤＣ－ＤＣコンバータは別々の筐体に設置されており、
    　前記第２の傾きは、前記インバータが出力抑制を開始する際の前記直流バスの電圧と、前記インバータが出力抑制を終了する際の前記直流バスの電圧との差分に基づき決定されることを特徴とした請求項１または２に記載の電力変換装置。     The DC side of the inverter is connected via a DC bus to a DC-DC converter that controls the output of a predetermined DC power source,
    The inverter and the DC-DC converter are installed in separate cases,
    The second slope is determined based on a difference between a voltage of the DC bus when the inverter starts output suppression and a voltage of the DC bus when the inverter ends output suppression. The power converter according to claim 1 or 2.
  5. 　前記制御回路は、出力抑制事由が発生したとき前記インバータの出力電流または出力電力を抑制することを特徴とする請求項１から４のいずれかに記載の電力変換装置。 The power conversion device according to any one of claims 1 to 4, wherein the control circuit suppresses an output current or output power of the inverter when an output suppression event occurs.
  6. 　前記制御回路は、前記第１の傾きの値および前記第２の傾きの値の少なくとも一方を変更可能であることを特徴とする請求項１から５のいずれかに記載の電力変換装置。 The power converter according to any one of claims 1 to 5, wherein the control circuit is capable of changing at least one of the first slope value and the second slope value.
  7. 　前記制御回路は、出力抑制事由の種類に応じて、前記第１の傾きの値および前記第２の傾きの値の少なくとも一方を変えることを特徴とする請求項６に記載の電力変換装置。 The power converter according to claim 6, wherein the control circuit changes at least one of the first slope value and the second slope value in accordance with a type of an output suppression reason.
  8. 　直流バスから供給される直流電力を交流電力に変換し、当該交流電力を負荷または電力系統へ供給するインバータと、
    　前記インバータを制御する制御回路と、
    　所定の直流電源の出力を制御し、当該出力を前記直流バスに供給するＤＣ－ＤＣコンバータと、を備え、
    　前記制御回路は、出力抑制事由の発生により前記インバータの出力を低下させる際の第１の傾きより、前記出力抑制事由の消滅により前記インバータの出力を上昇させる際の第２の傾きを緩く制御することを特徴とする電力変換システム。     An inverter that converts DC power supplied from a DC bus into AC power and supplies the AC power to a load or power system;
    A control circuit for controlling the inverter;
    A DC-DC converter that controls the output of a predetermined DC power source and supplies the output to the DC bus,
    The control circuit controls the second slope when increasing the output of the inverter by the disappearance of the output suppression reason more gently than the first slope when reducing the output of the inverter due to the occurrence of the output suppression reason. A power conversion system characterized by that.
PCT/JP2018/001802 2017-03-30 2018-01-22 Power conversion device, power conversion system WO2018179712A1 (en)

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Publication number Priority date Publication date Assignee Title
CN113965098A (en) * 2021-09-22 2022-01-21 江苏阿诗特能源科技有限公司 Single-phase inverter control method under nonlinear load and related device

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JPH08280136A (en) * 1995-04-05 1996-10-22 Fuji Electric Co Ltd Method for controlling distributed power supply linked with power system
JPH11206021A (en) * 1997-12-29 1999-07-30 Hitachi Ltd Distributed power generation system

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Publication number Priority date Publication date Assignee Title
JPH08280136A (en) * 1995-04-05 1996-10-22 Fuji Electric Co Ltd Method for controlling distributed power supply linked with power system
JPH11206021A (en) * 1997-12-29 1999-07-30 Hitachi Ltd Distributed power generation system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113965098A (en) * 2021-09-22 2022-01-21 江苏阿诗特能源科技有限公司 Single-phase inverter control method under nonlinear load and related device
CN113965098B (en) * 2021-09-22 2023-04-07 江苏阿诗特能源科技有限公司 Single-phase inverter control method under nonlinear load and related device

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