Control device for power converter and power converter

Abstract

A power conversion device control device comprising: an effective power calculation section that acquires an electric current value and a voltage value measured on an AC side of a power conversion device, and calculates an effective power value, which is a measurement value for the effective power output by the power conversion device, on the basis of the acquired electric current value and voltage value; an integration unit that acquires the effective power value from the effective power value calculation section and, only when the acquired effective power value is in a charging direction, integrates the effective power value to calculate a charging power; a gain unit that calculates a first control value obtained by multiplying the charging power integrated by the integration unit and a prescribed gain; a DC voltage determination section that acquires the first control value calculated by the gain unit, calculates a DC voltage value from the charging power on the basis of the acquired first control value, and determines whether the calculated DC voltage value is at or above a prescribed threshold value; and an addition unit that, when it is determined by the DC voltage determination section that the DC voltage value is at or above the prescribed threshold value, adds together a prescribed effective power command value and the first control value and implements P droop control.

Description

[Technical Field]

[0001] The present invention relates to a control device for a power converter and a power converter. [Background technology]

[0002] Conventionally, power converters have employed feedforward control based on grid voltage. However, conventional feedforward control has difficulty dealing with the steep and abnormal levels of output voltage increase that occur in abnormal situations, such as the sudden disconnection of the power grid from the power converter. In this regard, improved power converters are known that suppress abnormal increases in output voltage (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent No. 6973657 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Incidentally, in the power conversion device described above, for example, once operation starts, it is operated under the control of a DC-AVR (Direct Current-Automatic Voltage Regulator). When operation is performed under the control of a DC-AVR (hereinafter also simply referred to as "DC-AVR"), the DC voltage is controlled to be maintained at a predetermined value, and the DC voltage can be stabilized to a predetermined value.

[0005] However, with existing control systems, for example, if the active power command value is 0% during DC-AVR operation and there is a negative offset in the detection system, the power converter will perform charging operation, which can lead to unstable voltage control. In other words, in such cases, the DC-AVR control becomes unstable and can cause DC overvoltage, which was a problem.

[0006] Therefore, the purpose of this disclosure is to suppress voltage control instability by introducing P-droop control to the power converter. [Means for solving the problem]

[0007] A control device for a power converter according to one embodiment is characterized by comprising: an active power calculation unit that acquires current and voltage values ​​measured on the AC side of the power converter and calculates an active power value, which is a measured value of the active power output by the power converter, based on the acquired current and voltage values; an integrator that acquires the active power value from the active power calculation unit and calculates charging power by integrating the active power value only when the acquired active power value is in the charging direction; a gainer that calculates a first control value by multiplying the charging power integrated by the integrator by a predetermined gain; a DC voltage determination unit that acquires the first control value calculated by the gainer, calculates a DC voltage value from the charging power based on the acquired first control value, and determines whether the calculated DC voltage value is above a predetermined threshold; and an adder that, when the DC voltage determination unit determines that the DC voltage value is above a predetermined threshold, adds a predetermined active power command value and the first control value to execute P-droop control.

[0008] A power conversion device according to one embodiment is characterized by comprising an inverter that converts DC power to AC power, and the control device described above. [Effects of the Invention]

[0009] According to this disclosure, by introducing P-droop control to the power converter, it is possible to suppress the instability of voltage control that occurs when the active power command value takes a value of 0% and a negative offset is applied to the detection system. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of the configuration of a control device and a power converter according to one embodiment of the power converter. [Figure 2] This figure shows an example of the control configuration and processing of P-droop control performed in the power control unit of the control device shown in Figure 1. [Figure 3] This is a conceptual diagram showing an example of the hardware configuration of the processing circuit of the control device in the embodiment shown in Figures 1 and 2. [Modes for carrying out the invention]

[0011] The control device and embodiments of the power converter related to this disclosure will be described below with reference to the drawings.

[0012] <One Embodiment> Figure 1 is a diagram showing an example of the configuration of the control device 30 and the power converter 1 of a power converter 1 according to one embodiment. In Figure 1, the power converter 1 is connected to a DC power supply 4 via a DC bus 2 at one end (input side) on the left side of Figure 1, and to an AC power system 5 via an AC circuit 3 at the other end (output side) on the right side of Figure 1.

[0013] The power converter 1 converts, for example, the DC power supplied from the DC power source 4 (DC side) into AC power, and outputs the converted AC power to the AC power system 5 (AC side). The power converter is also called a "PCS (Power Conditioning System)" or "power conditioner".

[0014] In this embodiment, the power converter 1 is described as a photovoltaics-power conditioning system (PV-PCS) for photovoltaics power generation (PV). However, the power converter 1 may be, for example, a power converter for a binary power generation system.

[0015] As shown in Figure 1, the power converter 1 includes a DC switch 11, a DC capacitor 12, an inverter 13, an AC reactor 14, an AC capacitor 15, and an AC switch 16. The power converter 1 also includes a first current sensor 21, a first voltage sensor 22, a second current sensor 23, a second voltage sensor 24, a third current sensor 25, and a control device 30. Although the wiring is omitted in the figure, the control device 30 is electrically connected to each element of the power converter 1.

[0016] The DC bus 2 connects the DC power supply 4 to the DC terminal (input side) of the inverter 13 in the power converter 1. The DC bus 2 has a positive bus and a negative bus, and supplies DC power supplied from the DC power supply 4 to the inverter 13. For example, the DC bus 2 has a first current sensor 21, a DC switch 11, a first voltage sensor 22, and a DC capacitor 12 arranged in order from the DC power supply 4 to the DC terminal of the inverter 13.

[0017] The AC circuit 3 connects the AC terminal (output side) of the inverter 13 in the power conversion device 1 to the AC power system 5. The AC circuit 3 is a three-phase three-wire three-phase AC circuit that supplies three-phase AC power, which is a combination of three single-phase AC circuits with phases of current or voltage shifted from each other, using three wires, cables, or conductors. The AC circuit 3 supplies the AC power converted by the inverter 13 to the AC power system 5. The AC circuit 3 is arranged in the following order from the AC terminal of the inverter 13 toward the AC power system 5: a second current sensor 23, an AC reactor 14, an AC capacitor 15, an AC switch 16, a second voltage sensor 24, and a third current sensor 25.

[0018] The DC power supply 4 is connected to the DC terminal (input terminal) of the inverter 13 via the DC bus 2. In this embodiment, the DC power supply 4 is described as a solar panel (photovoltaic panel, PV panel), but it may be a binary power generator or the like. The DC power supply 4 supplies DC power (generated by, for example, the solar panel) to the inverter 13 via the DC bus 2.

[0019] The AC power system (system) 5 is connected to the AC terminal (output terminal) of the inverter 13 via the AC circuit 3. The AC power system 5 is connected to a transformer (not shown) and is an integrated system of power generation, transformation, transmission, and distribution for supplying AC power transformed by the transformer (not shown) to the power receiving equipment of consumers, and for example, an unspecified load is connected to it. Hereinafter in this specification and drawings, the AC power system 5 will also be simply referred to as "power system 5" or "system 5". The AC power system 5 may be a power system, for example, an electric motor, a generator, or other AC load.

[0020] The DC switch (DC circuit breaker) 11 is installed in series between the first current sensor 21 and the first voltage sensor 22 on the DC bus 2. The DC switch 11 switches the DC bus 2 between the DC power supply 4 and the inverter 13 on (connects) or off (disconnects) according to an on or off instruction from, for example, the control device 30 or an operator (not shown). When the DC switch 11 is opened, the DC power supplied from the DC power supply 4 to the inverter 13 is interrupted. Hereinafter, in this specification and drawings, the DC switch 11 is also referred to as the "DC (Direct Current) switch 11".

[0021] The DC capacitor 12 is installed in the DC bus 2 between the first voltage sensor 22 and the DC terminal of the inverter 13. The DC capacitor 12 is a smoothing capacitor that smooths the DC voltage output from the DC power supply 4. When the DC switch 11 is closed, for example, the DC capacitor 12 is charged by the DC power from the DC power supply 4 and its voltage rises, and when the DC switch 11 is open, it is discharged by, for example, a discharge circuit or discharge resistor (not shown) and its voltage falls. Hereinafter in this specification and drawings, the DC capacitor 12 will also be referred to as "DC capacitor 12".

[0022] The inverter (inverter circuit) 13 has one end, which is the DC end, connected to a DC capacitor 12 and a DC switch 11 via a DC bus 2, and the other end, which is the AC end, connected to an AC reactor 14 via an AC circuit 3. The inverter 13 is constructed of multiple switching elements, such as IGBTs (Insulated Gate Bipolar Transistors). The inverter 13 is controlled, for example, by a pulse width modulation (PWM) signal, which is the gate drive signal (gate signal G) of the switching elements generated by the pulse width modulation (PWM) control unit 58 described later.

[0023] The inverter 13 acquires DC power supplied from the DC power supply 4 from one end, converts the acquired DC power into AC power according to control by a pulse width modulation signal (gate signal G), and outputs it from the other end, which is the output end, to supply it to the grid 5. In this specification and the drawings, the inverter 13 will also be referred to as the "inverter circuit 13," and the pulse width modulation signal will also be referred to as the "PWM signal."

[0024] The AC reactor 14 is connected in series with the AC terminal of the inverter 13 in the AC circuit 3. The AC reactor 14 is a smoothing element that has effects such as reducing noise and suppressing surge voltage. The AC reactor 14, together with the AC capacitor 15 connected in an L-shape via the branch point 15a, for example, constitutes an LC filter circuit (filter circuit) that reduces ripple (vibration) generated when the switching elements (not shown) of the inverter 13 switch. Hereinafter, in this specification and drawings, the AC reactor 14 will also be referred to as the "AC (Alternating Current) reactor 14".

[0025] The AC capacitor 15 is an electronic component that stores or releases electricity (charge), and in the AC circuit 3, it is connected in an L-shape to the AC reactor 14 via a branch point 15a. The AC capacitor 15, for example, together with the L-shaped connected AC reactor 14, constitutes an LC filter circuit (filter circuit) that reduces the ripple generated when the switching elements (not shown) of the inverter 13 switch. By constituting a filter circuit together with the AC reactor 14, the AC capacitor 15 suppresses the outflow of harmonics (harmonic currents) to the system 5 side. Hereinafter, in this specification and drawings, the AC capacitor 15 will also be referred to as "AC capacitor 15".

[0026] The AC switch (AC circuit breaker) 16 is installed in series between the AC reactor and AC capacitor and the power system 5 in the AC circuit 3. The AC switch 16 switches the AC circuit 3 between the inverter 13 and the power system 5 on (connects) or off (disconnects) according to an on or off instruction from, for example, a control device 30 or an operator (not shown). When the AC switch 16 is opened, the AC power supplied from the inverter 13 to the power system 5 is cut off. Hereinafter, in this specification and drawings, the AC switch 16 will also be referred to as "AC switch 16".

[0027] The first current sensor 21 is, for example, a known DC ammeter or DC current sensor, and is placed between the DC power supply 4 and the DC switch 11, and receives the DC current I flowing from the DC power supply 4. DC The value of is detected. Note that the position where the first current sensor 21 is placed is not limited to the position shown in Figure 1, but rather the DC current I flowing from the DC power supply 4. DC Any location where the value of can be detected is acceptable. Hereafter, in this specification and the drawings, the DC current I DC The value of is the DC current value I DC ", or simply "DC current I DC It is also called the "first current sensor 21". The DC current I detected by the first current sensor 21 DC This is acquired by the control device 30.

[0028] The first voltage sensor 22 is, for example, a known DC voltmeter or DC voltage sensor, etc., and is arranged between the DC switch 11 and the DC capacitor 12 on the DC side, and the DC voltage V of the DC power supply 4 DC of is detected. Note that the position where the first voltage sensor 22 is arranged is not limited to the position shown in FIG. 1, and any position where the value of the DC voltage V of the DC power supply 4 DC can be detected is acceptable. Hereinafter, in this specification, drawings, etc., the value of the DC voltage V DC is also referred to as "DC voltage value V DC ", or simply "DC voltage V DC ". The DC voltage V detected by the first voltage sensor 22 DC is acquired by the control device 30.

[0029] The second current sensor 23 is, for example, a known AC ammeter or AC current sensor, etc., and is arranged between the inverter 13 and the AC reactor 14 on the AC side, and the inverter output current I of the three-phase AC current which is the output current of the inverter 13 AC of is detected. Note that the position where the second current sensor 23 is arranged is not limited to the position shown in FIG. 1, and any position where the value of the inverter output current I which is the output current of the inverter 13 AC can be detected is acceptable. Hereinafter, in this specification, drawings, etc., the value of the inverter output current I AC is also referred to as "inverter output current value I AC ", or simply "inverter output current I AC ". The inverter output current I detected by the second current sensor 23 AC is acquired by the control device 30.

[0030] The second voltage sensor 24 is, for example, a known AC voltmeter or AC voltage sensor, etc., and is arranged between the AC switch 16 and the system 5 on the AC side, and the system voltage V which is the three-phase AC voltage in the system 5 Grid of is detected. Note that the position where the second voltage sensor 24 is arranged is not limited to the position shown in FIG. 1, and any position where the value of the system voltage V in the system 5 Grid can be detected is acceptable. Hereinafter, in this specification, drawings, etc., the system voltage VGrid The value is "System voltage value V Grid " or simply "System voltage V Grid It is also called the "system voltage V detected by the second voltage sensor 24. Grid This is acquired by the control device 30.

[0031] The third current sensor 25 is, for example, a known AC ammeter or AC current sensor, and is placed between the AC switch 16 on the AC side and the system 5, and measures the system current I, which is the three-phase AC current flowing through the system 5. Grid The value of is detected. Note that the position where the third current sensor 25 is placed is not limited to the position shown in Figure 1, and the system current I flowing through system 5 is detected. Grid Any location where the value of can be detected is acceptable. Hereafter, in this specification and the drawings, the system current I Grid The value is "System current value I Grid ", or simply "System Current I Grid It is also called the "system current I detected by the third current sensor 25." Grid This is acquired by the control device 30.

[0032] The control device 30 is installed, for example, inside or outside the power converter 1. Although wiring and other details are omitted in the figure, it is connected to each component of the power converter 1, including the inverter 13, by wire or wireless means. The control device 30 may also be implemented as a function of an inverter control circuit, which is not shown.

[0033] The control device 30 includes a processor 91 (see Figure 3), such as a CPU (Central Processing Unit), which operates by executing a program. The control device 30 also includes a storage unit 60 and a memory 92 (see Figure 3), and for example, operates the processor 91 by executing a predetermined program stored in the storage unit 60 or the memory 92, thereby comprehensively controlling the operation of the power converter 1.

[0034] The control device 30 may also operate according to instructions from a higher-level device (not shown) or instructions from an operator via an operation unit (not shown). The higher-level device (not shown) is, for example, one that comprehensively monitors and controls multiple power converters 1, and is connected to each power converter 1 by wire or wireless. The higher-level device (not shown) is, for example, an MSC (Main Site Controller) or an EMS (Energy Management System).

[0035] As shown in Figure 1, the control device 30 has the following configuration or functions. Specifically, the control device 30 functions as a PLL (Phase Locked Loop) control unit 41, a first conversion unit 42, a second conversion unit 43, and a power control unit 44. The control device 30 also functions as an MPPT (Maximum Power Point Tracking) control unit 51, a first subtraction unit 52, and a DC voltage control unit 53. Furthermore, the control device 30 functions as a first adder unit 54, a third conversion unit 55, a second subtraction unit 56, a current control unit 57, and a PWM control unit 58.

[0036] Each of the above configurations or functions may be implemented by a program executed by the processor 91 (see Figure 3) in the processing circuit 90 (see Figure 3) of the control device 30, or by the hardware 93 (see Figure 3) described later. The control device 30 executes a predetermined program and performs the following processing using the functions of each of the above parts.

[0037] The PLL control unit 41 is connected to the second voltage sensor 24, the first conversion unit 42, and the second conversion unit 43. The PLL control unit 41 receives the system voltage V, which is the detected value (measured value) of the second voltage sensor 24. Grid The PLL control unit 41 obtains information on the system voltage V. Grid PLL control is performed based on the system voltage V Grid The system outputs information of the reference phase θ synchronized with the first conversion unit 42 and the second conversion unit 43.

[0038] The first conversion unit 42 is connected to the second voltage sensor 24, the PLL control unit 41, and the power control unit 44. The first conversion unit 42 receives the system voltage V, which is the detected value (measured value) of the second voltage sensor 24. Grid The first conversion unit 42 acquires information on the reference phase θ output from the PLL control unit 41. Based on the acquired reference phase θ, the first conversion unit 42 performs a three-phase to two-phase conversion (dq conversion) and converts the system voltage V Grid Convert the values ​​into d-axis voltage and q-axis voltage.

[0039] The second conversion unit 43 is connected to the second current sensor 23, the third current sensor 25, the PLL control unit 41, and the power control unit 44. The second conversion unit 43 receives the inverter output current I, which is the value detected by the second current sensor 23. AC The information and the system current I, which is the value detected by the third current sensor 25. Grid The second conversion unit 43 acquires information and reference phase θ information output from the PLL control unit 41. Based on the acquired reference phase θ, the second conversion unit 43 performs three-phase to two-phase conversion (dq conversion) and outputs inverter output current I AC and system current I Grid Convert the values ​​into d-axis current and q-axis current.

[0040] The power control unit 44 is connected to the first conversion unit 42, the second conversion unit 43, the first adder 54, and the third conversion unit 55. The power control unit 44 obtains information on the d-axis voltage value and the q-axis voltage value from the first conversion unit 42, and obtains information on the d-axis current value and the q-axis current value from the second conversion unit 43. That is, the power control unit 44 obtains the system voltage V from the first conversion unit 42. Grid The measured value information is obtained, and the inverter output current I is obtained from the second conversion unit 43. AC and system current I Grid Obtain the measurement information.

[0041] The power control unit 44 determines the d-axis current command value I based on the acquired information on the d-axis voltage, q-axis voltage, d-axis current, and q-axis current. * d And the q-axis current command value I * qThe power control unit 44 calculates the acquired system voltage V. Grid Information on the measured values ​​and inverter output current I AC and system current I Grid Based on the measured values, the d-axis current command value I * d And the q-axis current command value I * q The power control unit 44 determines the d-axis current command value I * d The information is output to the first adder 54, and the obtained q-axis current command value I * q The information is output to the third conversion unit 55.

[0042] In this embodiment, the power control unit 44 receives the acquired grid voltage V Grid Information on the measured values ​​and inverter output current I AC The measured values ​​and the active power command value P described below. * Based on the information, P-droop control is performed. Therefore, in this embodiment, the d-axis current command value I obtained by the power control unit 44 * d The value shown is the value at which P-droop control is performed. Details of the P-droop control by the power control unit 44 will be described later (see Figure 2, etc.).

[0043] The MPPT control unit (Maximum Power Point Tracking control unit) 51 is connected to the first current sensor 21, the first voltage sensor 22, and the first subtraction unit 52. The MPPT control unit 51 receives the DC current I detected by the first current sensor 21 (measured value). DC This information, along with the DC voltage V detected (measured value) from the first voltage sensor 22, is used to determine the value. DC The MPPT control unit 51 obtains the information of the acquired DC current I. DC Information and DC voltage V DC Based on this information, for example, MPPT control is performed based on a known hill climbing method, and the DC voltage command value V * DC The MPPT control unit 51 calculates the DC voltage command value V. The range of MPPT control by the MPPT control unit 51 is determined for each device, for example. The MPPT control unit 51 calculates the DC voltage command value V.* DC The information is output to the first subtraction unit 52.

[0044] The first subtraction unit 52 is connected to the first voltage sensor 22 and the MPPT control unit 51. The first subtraction unit 52 receives the DC voltage V, which is the detected value (measured value) of the first voltage sensor 22. DC The information and the DC voltage command value V output from the MPPT control unit 51 * DC The first subtraction unit 52 obtains the DC voltage command value V. * DC DC voltage V DC The first subtraction unit 52 calculates the value obtained by subtracting the value (difference). * DC DC voltage V DC The information of the value obtained by subtracting (difference) is output to the DC voltage control unit 53.

[0045] The DC voltage control unit 53 is connected to the first subtraction unit 52 and the first addition unit 54. The DC voltage control unit 53 receives the DC voltage command value V output from the first subtraction unit 52. * DC DC voltage V DC The DC voltage control unit 53 obtains information on the value obtained by subtracting (difference). The DC voltage control unit 53 controls the obtained information to calculate the d-axis current command value. The DC voltage control unit 53 outputs the calculated d-axis current command value information to the first adder unit 54.

[0046] The first adder 54 is connected to the power control unit 44, the DC voltage control unit 53, and the third conversion unit 55. The first adder 54 receives the d-axis current command value I output from the power control unit 44. * d The first adder 54 acquires the information of the d-axis current command value I that is output from the DC voltage control unit 53. * d The first adding unit 54 calculates a value by adding the calculated d-axis current command value I * d The information obtained by adding the d-axis current command value is output to the third conversion unit 55.

[0047] The third conversion unit 55 is connected to the power control unit 44, the first addition unit 54, and the second subtraction unit 56. The third conversion unit 55 receives the information of the q-axis current command value I output from the power control unit 44 and the information of the value obtained by adding the d-axis current command value I output from the first addition unit 54 and the d-axis current command value. The third conversion unit 55 performs two-phase to three-phase conversion (inverse dq conversion) on the acquired information to calculate the current command value I. The third conversion unit 55 outputs the information of the calculated current command value I to the second subtraction unit 56. * q from the power control unit 44 and the information of the value obtained by adding the d-axis current command value I output from the first addition unit 54 and the d-axis current command value. * d The third conversion unit 55 performs two-phase to three-phase conversion (inverse dq conversion) on the acquired information to calculate the current command value I. * AC The third conversion unit 55 outputs the information of the calculated current command value I to the second subtraction unit 56. * AC to the second subtraction unit 56.

[0048] The second subtraction unit 56 is connected to the second current sensor 23, the third conversion unit 55, and the current control unit 57. The second subtraction unit 56 receives the information of the inverter output current I which is the detected value (measured value) of the second current sensor 23 and the information of the current command value I output from the third conversion unit 55. The second subtraction unit 56 calculates the value (difference) obtained by subtracting the inverter output current I from the current command value I. The second subtraction unit 56 outputs the information of the value (difference) obtained by subtracting the inverter output current I from the current command value I to the current control unit 57. AC The second subtraction unit 56 receives the information of the inverter output current I which is the detected value (measured value) of the second current sensor 23 and the information of the current command value I output from the third conversion unit 55. * AC The second subtraction unit 56 calculates the value (difference) obtained by subtracting the inverter output current I from the current command value I. * AC from the current command value I. AC The second subtraction unit 56 calculates the value (difference) obtained by subtracting the inverter output current I from the current command value I. * AC from the current command value I. AC The second subtraction unit 56 outputs the information of the value (difference) obtained by subtracting the inverter output current I from the current command value I to the current control unit 57.

[0049] The current control unit 57 is connected to the second subtraction unit 56 and the PWM control unit 58. The current control unit 57 receives the information of the value (difference) obtained by subtracting the inverter output current I from the current command value I output from the second subtraction unit 56. The current control unit 57 controls the acquired information to calculate the voltage command value. The current control unit 57 outputs the calculated voltage command value to the PWM control unit 58. * AC The current control unit 57 receives the information of the value (difference) obtained by subtracting the inverter output current I from the current command value I output from the second subtraction unit 56. AC The current control unit 57 controls the acquired information to calculate the voltage command value. The current control unit 57 outputs the calculated voltage command value to the PWM control unit 58.

[0050] The PWM control unit (pulse width modulation control unit) 58 is connected to the inverter 13 and the current control unit 57. The PWM control unit 58 obtains a voltage command value from the current control unit 57. Based on the obtained voltage command value, the PWM control unit 58 performs PWM control and generates a gate signal G, which is a pulse width modulation signal (PWM signal). The PWM control unit 58 outputs the generated gate signal G to the inverter 13 and controls the switching elements (not shown) of the inverter 13 to comprehensively control the operation of the inverter 13.

[0051] The storage unit 60 is a volatile or non-volatile storage medium such as an HDD (Hard Disk Drive), SSD (Solid State Drive), DRAM (Dynamic Random Access Memory), or other semiconductor memory. The storage unit 60 is connected to various parts of the control device 30, for example, by a bus (system bus) not shown, so that various types of information can be input and output. The storage unit 60 stores programs necessary for the operation of various parts of the control device 30, and various types of information are written to and read from the storage unit 60 by various parts of the control device 30.

[0052] Furthermore, the storage unit 60 stores values ​​detected (measured) by various sensors, such as the first current sensor 21. The storage unit 60 also stores various calculation formulas, coefficients, thresholds, etc., used in calculations by various units such as the power control unit 44 and the MPPT control unit 51, as well as predetermined rated values, limiter values, etc. The storage unit 60 also stores calculation results, etc., by various units such as the power control unit 44 and the MPPT control unit 51. The storage unit 60 may also store various command values ​​and operation instructions obtained from higher-level devices (not shown) or operators (not shown).

[0053] The storage unit 60 may be located outside the control device 30 and connected to the control device 30 by wire or wireless connection. It may also be an external storage medium such as a memory card or DVD (Digital Versatile Disc), or it may be online storage. Furthermore, the storage unit 60 may be the same as the memory 92 (see Figure 3) described later.

[0054] Figure 2 shows an example of the control configuration and processing of P-droop control performed in the power control unit 44 of the control device 30 shown in Figure 1. As shown in Figure 2, the power control unit 44 functions as follows by executing a predetermined program stored in, for example, the storage unit 60 or the memory 92 (see Figure 3) described later.

[0055] The power control unit 44 functions as an active power calculation unit 71, an integrator 72, a gain unit 73, a limiter 74, a DC voltage determination unit 75, a function activation unit 76, a logical AND circuit 77, a selector 78, and an adder 79. The power control unit 44 also functions as a subtractor 81, a feedback control unit 82 (e.g., PI (Proportional-Integral)), a second limiter 83, a feedforward unit 84, and a second adder 85.

[0056] Each of the above functions may be implemented by a program executed by the processor 91 (see Figure 3) in the processing circuit 90 (see Figure 3) of the control device 30, or by the hardware 93 (see Figure 3) described later. Each of the above parts executes a predetermined program and performs the following processing.

[0057] The active power calculation unit 71 obtains information on the d-axis voltage value and the q-axis voltage value from the first conversion unit 42 (see Figure 1), and information on the d-axis current value and the q-axis current value from the second conversion unit 43 (see Figure 1). As a result, the active power calculation unit 71 obtains information on the system voltage V from the first conversion unit 42. Grid The measured value information is obtained, and the inverter output current I is obtained from the second conversion unit 43. AC The measured information will be obtained. The active power calculation unit 71 will obtain the system voltage V Grid Information on the measured values ​​and inverter output current I ACBased on the measured values, the power converter 1 (inverter 13) calculates the measured value of the active power P it outputs. Hereinafter, in this specification and the drawings, the measured value of the active power P will also be referred to as the "measured value of active power P", the "active power value P", or simply "active power P". The active power calculation unit 71 outputs the calculated measured value of active power (active power value) P to the integrator 72 and the subtractor 81.

[0058] The integrator 72 obtains the active power measurement value P from the active power calculation unit 71 and determines whether the obtained active power measurement value P is in the charging direction. If the integrator 72 determines that the obtained active power measurement value P is in the charging direction, it integrates the active power measurement value P to calculate the charging power (energy amount). The integrator 72 then outputs the calculated charging power to the gain unit 73. On the other hand, if the integrator 72 determines that the obtained active power measurement value P is not in the charging direction (it is in the discharge direction), it terminates processing without integrating the active power value P. As a result, the integrator 72 integrates the active power value P only when the active power measurement value P is in the charging direction, so the power control unit 44 can perform P-droop control only when the active power measurement value P is in the charging direction.

[0059] The gain unit 73 acquires charging power from the integrator 72 and also acquires a predetermined gain K. The predetermined gain K is obtained, for example, by executing P-droop control, from the active power command value P * The value may be set such that it is in the discharge direction rather than the charging direction. The predetermined gain K may be a value calculated for each charging power, a value stored in the memory unit 60 for each charging power, or a value obtained from a higher-level device (not shown) or an operator (not shown). The gain unit 73 multiplies the acquired charging power by the predetermined gain K to calculate the first control value for P-droop control. The gain unit 73 outputs the calculated first control value to the limiter 74 and the DC voltage determination unit 75. As a result, the gain unit 73 multiplies the acquired charging power by the predetermined gain K only when the active power measurement value P is in the charging direction, so the power control unit 44 can execute P-droop control only when the active power measurement value P is in the charging direction.

[0060] The limiter 74 obtains a first control value from the gainer 73 and limits the power so that the obtained first control value becomes a second control value which is a value within a predetermined range. For example, the limiter 74 uses P-droop control to obtain the active power command value P from the first control value obtained from the gainer 73. * The limiter 74 restricts the value so that it does not become a charging direction (negative value) but a discharging direction (positive value), and this restricted value is set as the second control value. The limiter 74 outputs the second control value, which is the value obtained by restricting the first control value, to the selector 78. By providing the limiter 74, the first control value that would perform P-droop control in the charging direction (negative direction) is restricted (stopped), and as a result, P-droop control can be performed only in the discharging direction (positive direction). Furthermore, by providing the limiter 74, the d-axis current command value I is controlled by P-droop control. * d It can also suppress fluctuations that exceed the range limited by the limiter 74.

[0061] For example, the limiter 74 may be a switch that toggles whether or not to output the first control value. Also, for example, the value of the gain K used in the above-mentioned gainer 73 may be the active power command value P due to the execution of P-droop control. * When the value is set to a direction that is discharge rather than charge, the function of the limiter 74 may be omitted. In this case, the first control value calculated by the gain unit 73 is output to the selector 78.

[0062] The DC voltage determination unit 75 acquires a first control value output from the gain unit 73 and calculates (inversely calculates) the DC voltage from the charging power based on the acquired first control value. The DC voltage determination unit 75 then determines whether the calculated DC voltage value is above a predetermined threshold. If the DC voltage determination unit 75 determines that the calculated DC voltage value is above the predetermined threshold, it outputs "1" (high level) to the AND circuit 77. On the other hand, if the DC voltage determination unit 75 determines that the calculated DC voltage value is not above the predetermined threshold, it outputs "0" (low level) to the AND circuit 77. This limits the P-droop control from being overly sensitive to minor fluctuations between the discharge direction and charging direction of the active power measurement value P, thereby stabilizing the operation of the inverter 13 (power converter 1). In other words, this allows the power control unit 44 to execute P-droop control only when a sufficiently large amount of charging voltage has accumulated, thereby stabilizing the operation of the inverter 13 (power converter 1).

[0063] The function activation unit 76 monitors the operating mode and determines whether MPPT control or DC-AVR is being performed in the control device 30. Based on this determination, it outputs information on whether to enable the P-droop control function. If the function activation unit 76 determines, after monitoring the operating mode of the control device 30, that DC-AVR is being performed, it outputs information "1" (high level) to the AND circuit 77 indicating that the P-droop control function is enabled. On the other hand, if the function activation unit 76 determines, after monitoring the operating mode of the control device 30, that MPPT control is being performed, it outputs information "0" (low level) to the AND circuit 77 indicating that the P-droop control function is not enabled (disabled).

[0064] For example, if the power converter 1 is a power converter 1 for solar power generation, the power converter 1 (control device 30) performs MPPT control during normal daytime operation by the MPPT control unit 51 (see Figure 1) based on a known hill-climbing method, etc. According to MPPT control based on a known hill-climbing method, etc., the DC voltage command value V is set so that the power is always at its maximum. *DC This is constantly being updated and constantly fluctuating. Therefore, when P-droop control is performed by the MPPT control unit 51 while MPPT control is being performed, there is a concern that the P-droop control may interfere with the MPPT control. On the other hand, when DC-AVR is being performed in the power converter 1 (control device 30), the DC voltage command value V * DC Since it is fixed, the risk of P-droop control interfering with DC-AVR control is low.

[0065] Furthermore, for example, if the power converter 1 is a power converter 1 for solar power generation, and MPPT control is not performed in the power converter 1 (control device 30) (for example, outside of daytime), DC-AVR is performed. Also, for example, if the power converter 1 is a power converter 1 for a binary power generation system or a storage battery, DC-AVR is constantly performed in the power converter 1 (control device 30) when the power converter 1 is in operation. Therefore, as described in paragraph

[0006] , P-droop control is necessary to stabilize voltage control and suppress DC overvoltage.

[0066] Therefore, when the function activation unit 76 determines that DC-AVR is being performed in the power converter 1 (control device 30), it sets the P-droop control function to be enabled and outputs "1" (high level) to the AND circuit 77. On the other hand, when the function activation unit 76 determines that MPPT control is being performed in the power converter 1 (control device 30), it sets the P-droop control function to be disabled and outputs "0" (low level) to the AND circuit 77.

[0067] This prevents the risk that P-droop control will interfere with MPPT control when MPPT control is not being performed by the MPPT control unit 51. Furthermore, this allows the power control unit 44 to perform P-droop control to suppress DC overvoltage only when the power converter 1 is in DC-AVR mode and the concerns described in paragraph

[0006] exist.

[0068] The AND gate 77 obtains information from the function activation unit 76 regarding whether the P-droop control function is enabled or not. The AND gate 77 also obtains information from the DC voltage determination unit 75 regarding whether the DC voltage value is above a predetermined threshold or not.

[0069] Then, when the AND gate 77 obtains the information "1" indicating that the P-droop control function is enabled, and also obtains the information "1" indicating that the DC voltage value is above a predetermined threshold, it outputs the information "1" (high level) to the selector 78 indicating that P-droop control should be started. In other words, the AND gate 77 outputs the information "1" (high level) to the selector 78 indicating that P-droop control should be started only when the information obtained from the function activation unit 76 and the information obtained from the DC voltage determination unit 75 are both "1" and "1".

[0070] On the other hand, when the AND circuit 77 obtains at least one of the following pieces of information: information that the P-droop control function is not enabled ("0") or information that the DC voltage value is not above a predetermined threshold ("0"), it outputs information "0" (low level) to the selector 78 indicating that the P-droop control will not be started. In other words, when at least one of the information obtained from the function activation unit 76 and the information obtained from the DC voltage determination unit 75 is "0", the AND circuit 77 outputs information "0" (low level) to the selector 78 indicating that the P-droop control will not be started.

[0071] This allows for limiting P-droop control to only minor fluctuations between the discharge and charge directions of the active power measurement value P, preventing it from being performed. Furthermore, this prevents P-droop control from interfering with MPPT control, and since the power converter 1 suppresses DC overvoltage during DC-AVR operation, the power control unit 44 can perform P-droop control.

[0072] The selector 78 obtains the second control value from the limiter 74. If the function of the limiter 74 is omitted from the power control unit 44, the selector 78 obtains the first control value from the gain unit 73. The selector 78 also obtains the value "0.0" (control value) from, for example, the memory unit 60. Furthermore, the selector 78 obtains information from the AND gate 77 regarding whether or not to start P-droop control.

[0073] When the selector 78 receives the information "1" from the AND circuit 77 indicating that P-droop control should be started, it selects the second control value obtained from the limiter 74 (or the first control value obtained from the gain unit 73) and outputs it to the adder 79. On the other hand, when the selector 78 receives the information "0" from the AND circuit 77 indicating that P-droop control should not be started, it selects the control value "0.0" obtained from, for example, the memory unit 60 and outputs it to the adder 79.

[0074] This ensures that, for example, when the P-droop control function is disabled, such as during MPPT control, a control value of "0.0" is selected and output to the adder 79, preventing the P-droop control from affecting subsequent control stages.

[0075] The adder 79 receives a predetermined active power command value P from a higher-level device (not shown), such as an MSC or EMS. * Obtain the predetermined active power command value P. * This could be, for example, a value obtained based on a predetermined calculation or a predetermined simulation result, a value stored in the memory unit 60, or a value received from an operator (not shown) via an operation unit (not shown). The adder 79 also acquires the second control value (or first control value) or the control value "0.0" output from the selector 78. The adder 79 then acquires the active power command value P from, for example, a higher-level device (not shown). *The adder 79 then adds the value obtained from selector 78 (second control value (or first control value), or control value of "0.0") to perform P-droop control. The adder 79 then outputs the P-droop control value, which is the value after P-droop control has been performed, to the subtractor 81 and the feedforward unit 84. The P-droop control performed by the adder 79 suppresses instability in voltage control.

[0076] Here, for example, there may be a difference between the current and voltage values ​​at the output terminals of multiple power converters 1 that are monitored by a higher-level device (not shown) and output to the power system 5, and the current and voltage values ​​at the output terminal of the power converter 1 that is monitored by its own sensor. In this case, for example, corrections may be made so that there is no difference between these values, for example, by offsetting. For example, the active power command value P may be set to operate at -0.1%. * When this is output, it may appear to a higher-level device (not shown) that it is operating at 0%. In this case, the higher-level device (not shown) adjusts the active power command value P to appear as if it is operating at 0% from its perspective, using an offset or similar method, so that it appears to be operating at -0.1% from its perspective. * This may sometimes be output.

[0077] At this time, for example, suppose that due to some disturbance, the measured value of the active power P takes a value less than 0%, such as -1% or -2%, and the DC capacitor 12 (see Figure 1) is unintentionally charged. In this case, the power converter 1 (control device 30) attempts to control the system to discharge by outputting a command value of 0% or greater, such as 1% or 2%, using a DC-AVR or the like. However, due to the above-mentioned offset, for example, the active power command value P from a higher-level device (not shown) may be affected. * For example, a value of 0% or a negative value less than 0% may be given. In this case, generally, the power converter 1 (control device 30) controls the active power command value P, which is a request from the unillustrated higher-level device, rather than the DC-AVR control. * To prioritize this process, discharge may not be possible, and the DC voltage may become overvoltage.

[0078] Therefore, in this embodiment, for example, when the DC capacitor 12 (see Figure 1) is overcharged, that is, when the DC voltage value calculated by the DC voltage determination unit 75 is determined to be above a predetermined threshold, the adder 79 performs P droop control. This allows, for example, the active power command value P requested from a higher-level device (not shown) to be controlled. * Even if the value is 0% or a negative value less than 0%, the active power command value P * A positive value is added to this, and the control device 30 can control the discharge direction using a DC-AVR or the like. This makes it possible to control the DC voltage to a constant value using a DC-AVR or the like, thus stabilizing the voltage control and suppressing DC overvoltage.

[0079] For example, if the power converter 1 is a power converter 1 for solar power generation, once the DC voltage is stabilized to a predetermined value by DC-AVR, the control device 30 can terminate DC-AVR and start MPPT control. As mentioned above, when MPPT control is started, the function activation unit 76 outputs information indicating that the P-droop control function is not enabled, and therefore P-droop control is not performed.

[0080] The subtractor 81 obtains the P-droop control value from the adder 79, which is the value obtained when P-droop control is performed by the adder 79. The subtractor 81 also obtains the active power measurement value P from the active power calculation unit 71. Then, the subtractor 81 subtracts the obtained active power measurement value P from the obtained P-droop control value (takes the difference) to calculate the active power control value. Finally, the subtractor 81 outputs the calculated active power control value to the feedback control unit 82.

[0081] The feedback control unit 82 obtains the active power control value calculated by the subtractor 81 from the subtractor 81, and performs feedback control on the obtained active power control value to obtain a feedback control value. The feedback control unit 82 outputs the obtained feedback control value to the second limiter 83.

[0082] The second limiter 83 obtains the feedback control value obtained by the feedback control unit 82 from the feedback control unit 82 and limits the obtained feedback control value to a second feedback control value which is a value that falls within a predetermined range. The second limiter 83 outputs the second feedback control value, which is the value of the feedback control value that has been limited, to the second adder 85. With the provision of the second limiter 83, the d-axis current command value I * d This can suppress fluctuations that exceed the range limited by the second limiter.

[0083] The feedforward unit 84 obtains the P-droop control value from the adder 79, which is the value obtained by the P-droop control performed by the adder 79, and performs feedforward control on the obtained P-droop control value to obtain a feedforward control value. The feedforward unit 84 outputs the obtained feedforward control value to the second adder 85. Note that the function of the feedforward unit 84 may be omitted, and only feedback control by the feedback control unit 82 may be performed on the P-droop control value.

[0084] The second adder 85 obtains a second feedback control value from the second limiter 83, which is the value to which the feedback control value is limited by the second limiter 83. The second adder 85 obtains a feedforward control value from the feedforward unit 84. Then, the second adder 85 adds the obtained second feedback control value and the obtained feedforward control value to obtain the d-axis current command value I * d The second adder 85 calculates the calculated d-axis current command value I. * d The information is output to the first adder 54 (see Figure 1). When the feedforward unit 84 is not functioning, the second adder 85 adds the second feedback control value obtained from the second limiter 83 and the P-droop control value obtained from the adder 79 to obtain the d-axis current command value I * d Calculate.

[0085] <Effects of one embodiment> As described above, according to one embodiment shown in Figures 1 and 2, by introducing P-droop control to the power converter, it is possible to suppress the instability of voltage control when the active power command value takes a value of 0% or less and a negative offset is applied.

[0086] Furthermore, according to one embodiment shown in Figures 1 and 2, the integrator 72 calculates the charging power (energy amount) by integrating the active power measurement value P only when it determines that the active power measurement value P is in the charging direction. In addition, the gain unit 73 multiplies the acquired charging power by a predetermined gain K only when the active power measurement value P is in the charging direction. As a result, the control device 30 (power control unit 44) can perform P-droop control only when the active power measurement value P is in the charging direction.

[0087] Furthermore, according to one embodiment shown in Figures 1 and 2, the limiter 74 limits the first control value that performs P-droop control in the charging direction (negative direction). As a result, the control device 30 (power control unit 44) can perform P-droop control only in the discharge direction (positive direction).

[0088] Furthermore, according to one embodiment shown in Figures 1 and 2, the DC voltage determination unit 75 outputs "1" (high level) to the AND circuit 77 only when it determines that the calculated DC voltage value is above a predetermined threshold. As a result, the control device 30 (power control unit 44) can perform P-droop control only when a sufficient amount of charging voltage has accumulated, preventing overly sensitive P-droop control.

[0089] Furthermore, according to one embodiment shown in Figures 1 and 2, the AND circuit 77 outputs information "1" (high level) to the selector 78 indicating that P-droop control should be started only when the information from the function activation unit 76 and the information from the DC voltage determination unit 75 are both "1" and "1". This prevents the control device 30 (power control unit 44) from performing P-droop control too sensitively and prevents P-droop control from interfering with MPPT control.

[0090] Furthermore, according to one embodiment shown in Figures 1 and 2, when the selector 78 receives the information "0" from the AND circuit 77 indicating that P-droop control should not be started, it selects a control value of "0.0" and outputs it to the adder 79. This allows the control device 30 (power control unit 44) to ensure that when the P-droop control function is disabled, the P-droop control does not affect the control of subsequent stages.

[0091] <Example Hardware Configuration> Figure 3 is a conceptual diagram showing an example of the hardware configuration of the processing circuit 90 in the control device 30 in the embodiments shown in Figures 1 and 2. Each of the functions described above is realized by the processing circuit 90. In one embodiment, the processing circuit 90 comprises at least one processor 91 and at least one memory 92. In another embodiment, the processing circuit 90 comprises at least one dedicated hardware 93.

[0092] If the processing circuit 90 includes at least one processor 91 and at least one memory 92, each function is realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the memory 92. The processor 91 realizes each function by reading and executing the program stored in the memory 92.

[0093] At least one processor 91 is, for example, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP, etc. At least one memory 92 is, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, etc., a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisc, a DVD, etc.

[0094] If the processing circuit 90 includes at least one dedicated hardware 93, the processing circuit 90 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. Each function of the control device 30 is realized by the processing circuit 90.

[0095] Each function of the control device 30 may be implemented in part or in whole by hardware, or as a program executed by a processor. In other words, the control device 30 can also be implemented by a computer and a program, and the program can be stored on a storage medium or provided via a network.

[0096] <Supplementary information on the embodiment> As described above, the embodiments shown in Figures 1 to 3 illustrate a power converter 1 for solar power generation as one aspect of the disclosure, but the disclosure is not limited to this. The disclosure can be applied to any power converter 1 that performs only charging, power generation, and discharging as its basic operation, such as a power converter for a binary power generation system or a power converter for a predetermined energy storage system (ESS).

[0097] Furthermore, while the embodiments shown in Figures 1 to 3 illustrate an example of a power conversion device 1 for solar power generation and a control device 30 therewith, the disclosure is not limited to this. The disclosure can also be implemented as a control method in which processing steps are performed in each part of the control device 30.

[0098] Furthermore, this disclosure can also be implemented as a control program that causes a computer to execute processing steps in each part of the control device 30.

[0099] Furthermore, this disclosure can also be implemented as a storage medium (non-temporary computer-readable storage medium) on which the control program is stored. The control program can be stored and distributed on removable media such as a CD (Compact Disc), DVD (Digital Versatile Disc), or USB (Universal Serial Bus) memory. The control program may also be uploaded to a network via a network interface (not shown) of the control device 30, or it may be downloaded from the network and stored in the storage unit 60, etc.

[0100] The features and advantages of the embodiments will become clear from the detailed description above. This is intended to be so as not to deviate from the spirit and scope of the claims, that the features and advantages of the embodiments described above are included. Furthermore, any improvement and modification should be readily conceivable to a person with ordinary skill in the art. Therefore, there is no intention to limit the scope of inventive embodiments to those described above, and it is also possible to rely on appropriate improvements and equivalents that fall within the scope disclosed in the embodiments. [Explanation of Symbols]

[0101] 1...Power converter; 2...DC busbar; 3...AC circuit; 4...DC power supply; 5...AC power system (power system, system); 11...DC switch (DC switch, DC circuit breaker); 12...DC capacitor (DC capacitor); 13...Inverter (inverter circuit); 14...AC reactor (AC reactor); 15...AC capacitor (AC capacitor); 15a...Branch point; 16...AC switch (AC switch, AC circuit breaker); 21...First current sensor; 22...First voltage sensor; 23...Second current sensor; 24...Second voltage sensor; 25...Third current sensor; 30...Control device; 41...PLL control unit; 42...First conversion unit; 43...Second conversion unit; 44...Power control unit; 51…MPPT control unit (Maximum Power Point Tracking control unit); 52…First subtraction unit; 53…DC voltage control unit; 54…First addition unit; 55…Third conversion unit; 56…Second subtraction unit; 57…Current control unit; 58…PWM control unit (Pulse Width Modulation control unit); 60…Memory unit; 71…Active power calculation unit; 72…Integrator; 73…Gain unit; 74…Limiter; 75…DC voltage determination unit; 76…Function activation unit; 77…Logic AND circuit; 78…Selector; 79…Adder; 81…Subtractor; 82…Feedback control unit; 83…Second limiter; 84…Feedforward unit; 85…Second adder; 90…Processing circuit; 91…Processor; 92…Memory; 93…Hardware; G…Gate signal; I * d ...d-axis current command value; I * q ...q-axis current command value; I * AC ...current command value; I AC ...Inverter output current value (inverter output current); I DC ...DC current value (DC current); I Grid ...System current value (system current); K...Gain; P...Active power measurement value (active power value, active power); P * ...Active power command value; V * DC ...DC voltage command value; V DC ...DC voltage value (DC voltage); V Grid ...System voltage value (system voltage); θ...reference phase

Claims

1. An active power calculation unit that acquires current and voltage values ​​measured on the AC side of a power converter, and calculates an active power value, which is a measured value of the active power output by the power converter, based on the acquired current and voltage values, An integrator that obtains the active power value from the active power calculation unit and calculates the charging power by integrating the active power value only when the obtained active power value is in the charging direction, A gainer calculates a first control value obtained by multiplying the charging power integrated by the integrator by a predetermined gain, A DC voltage determination unit that acquires the first control value calculated by the gainer, calculates a DC voltage value from the charging power based on the acquired first control value, and determines whether the calculated DC voltage value is above a predetermined threshold, When the DC voltage determination unit determines that the DC voltage value is equal to or greater than the predetermined threshold, an adder is used to add a predetermined active power command value and the first control value and execute P-droop control. A control device for a power conversion device, characterized by comprising:

2. In the control device according to claim 1, A function activation unit monitors the operating mode of the power converter and outputs information on whether the P-droop control function is enabled based on the operating mode. A logical AND circuit that, when it obtains information from the function activation unit indicating that the P-droop control function is enabled, and when it obtains information from the DC voltage determination unit indicating that the DC voltage value is determined to be above a predetermined threshold, outputs information indicating that the P-droop control should be started, A selector that outputs the first control value calculated by the gainer when the AND circuit outputs information indicating that the P-droop control should be started, and outputs a control value of 0.0 when the AND circuit does not output information indicating that the P-droop control should be started, Furthermore, The adder performs the P-droop control by adding the predetermined active power command value and the value output from the selector. A control device for a power conversion device, characterized by the following features.

3. In the control device according to claim 2, The function activation unit outputs information indicating that the P-droop control function is enabled when the power converter is in DC-AVR mode. A control device for a power conversion device, characterized by the following features.

4. In the control device according to claim 3, A limiter that acquires the first control value calculated by the gainer and limits the acquired first control value to a second control value which is a value that falls within a predetermined range, Furthermore, When the AND gate outputs information indicating that the P-droop control should be started, the selector outputs the second control value, which is the value of the first control value limited by the limiter. When the AND gate does not output information indicating that the P-droop control should be started, the selector outputs a control value of 0.

0. A control device for a power conversion device, characterized by the following features.

5. In the control device according to claim 4, A subtractor calculates an active power control value by subtracting the active power value from the P-droop control value, which is the value obtained by the P-droop control performed by the adder, A feedback control unit that performs feedback control on the active power control value calculated by the subtractor to obtain a feedback control value, A second adder calculates a d-axis current command value by adding the P-droop control value and the feedback control value obtained by the feedback control unit, A control device for a power conversion device, further characterized by comprising the following features.

6. In the control device according to claim 5, A feedforward unit that performs feedforward control on the P-droop control value to obtain a feedforward control value, Furthermore, The second adder calculates the d-axis current command value by adding the feedforward control value obtained by the feedforward unit and the feedback control value. A control device for a power conversion device, characterized by the following features.

7. In the control device according to claim 6, A second limiter acquires the feedback control value obtained by the feedback control unit and limits the acquired feedback control value to a second feedback control value which is a value that falls within a predetermined range. Furthermore, The second adder calculates the d-axis current command value by adding the feedforward control value and the second feedback control value, which is a value limited by the second limiter. A control device for a power conversion device, characterized by the following features.

8. An inverter that converts DC power to AC power, A control device according to any one of claims 1 to 7, A power conversion device characterized by comprising the following features.

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