JP2023141962A - Electric power system and power converter - Google Patents

Abstract

To perform prompt optimization of control even in a case of configuration change in a DC grid.SOLUTION: An electric power system provides a plurality of power converters which includes: a power conversion part connected to a DC bus, for converting and outputting inputted power; a signal output part for outputting an investigation signal to the bus in response to an output command; a measurement part for measuring an electric characteristic value of the bus; a characteristic measurement part for measuring a transfer characteristic of the bus to the investigation signal in response to a measurement command, and transmitting transfer characteristic information indicating the measured transfer characteristic to a central control device; and an output control part for controlling output of the power conversion part based on the measured electric characteristic value and a control parameter transmitted from the central control device, and provides a central control device which includes: the bus; a command part for transmitting an output command to a selected power converter and transmitting a measurement command to a power converter other than the transmission destination of the output command; and a setting part for transmitting a control parameter, set based on the transfer characteristic information transmitted from the power converter, to the power converter.SELECTED DRAWING: Figure 2

Description

The present invention relates to power systems and power converters.

Electricity networks that use locally produced electricity for local consumption are attracting attention as an alternative to large-scale electricity networks that rely on fossil or nuclear energy. Electric power networks that use locally produced and consumed electricity include photovoltaic (PV) power generation devices that generate electricity using renewable energy, stationary power storage devices, electric vehicles (EV), etc. A wide variety of devices are connected to the DC bus via DC/DC converters. Since these devices are direct current power sources, studies are underway to optimize direct current (DC) power networks (DC grids).

Examples of methods for optimizing control of the DC grid include methods disclosed in Non-Patent Documents 1 and 2. These methods derive the equivalent circuit of a DC grid, and are stability determination methods using a root locus-based parameter design approach and a Nyquist diagram. /Conducts control design for DC converters.

Santiago Sanchez, Marta Molinas, Marco Degano, Pericle Zanchetta, “Stability evaluation of a DC micro-grid and future interconnection to an AC system”, Renewable Energy, February 2014, Volume 62, P.649-656 Sheng Liu, Peng Su, Lanyong Zhang, "A Virtual Negative Inductor Stabilizing Strategy for DC Microgrid With Constant Power Loads", IEEE Access, October 2018, Volume 6, P.59728-59741

In a DC grid, the number of DC/DC converters connected to a DC bus may change due to addition or removal, and the configuration may change. When the configuration of the DC grid changes in this way, the methods described in Non-Patent Documents 1 and 2 derive a new equivalent circuit according to the change in configuration, and control the DC/DC converter using the derived equivalent circuit. Since it is necessary to design the control, it takes time to design the control, making it difficult to respond quickly to optimization of the control of the DC/DC converter.

The present invention has been made in view of the above, and an object of the present invention is to provide a technology that allows quick optimization of control even if there is a change in the configuration of a DC grid.

In order to solve the above-mentioned problems and achieve the objectives, a power system according to one aspect of the present invention includes a DC power converter connected to a DC bus and converting and outputting input power, and a central a signal output unit that outputs a survey signal to the bus in response to an output command transmitted from a control device; a measurement unit that measures electrical characteristic values of the bus; and a central control unit that controls transfer characteristics of the bus in response to the survey signal. a characteristic measuring unit that measures in response to a measurement command transmitted from the device and transmits transfer characteristic information indicating the measured transfer characteristic to the central control unit; and a storage unit that stores control parameters transmitted from the central control unit. and an output control unit that controls the output of the power conversion unit based on the electrical characteristic value measured by the measurement unit and the control parameter stored in the storage unit. , a bus to which the plurality of power converters are connected; a command unit that transmits an output command to the selected power converter and transmits a measurement command to the power converter other than the destination of the output command; a characteristic acquisition unit that acquires transfer characteristic information transmitted from the power converter that has received the command; and a characteristic acquisition unit that sets the control parameter based on the transfer characteristic information and transmits the set control parameter to the power converter. and a central control device having a setting section.

In the power system according to one aspect of the present invention, the central control device may detect an abnormality in the bus based on the transfer characteristic information.

In the power system according to one aspect of the present invention, the setting unit selects a power converter to which power is to be accommodated based on the transfer characteristic information, and adjusts the power so that power is accommodated from the selected power converter. Control parameters of the transducer may also be set.

A power converter according to one aspect of the present invention includes a DC power conversion unit that is connected to a DC bus and converts and outputs input power, and a DC power conversion unit that converts input power and outputs the converted power, and a DC power conversion unit that converts input power and outputs the converted power. a signal output unit that outputs a survey signal to the bus; a measurement unit that measures the electrical characteristic value of the bus; and a measurement unit that measures the transfer characteristic of the bus in response to the survey signal in response to a measurement command transmitted from the central controller; a characteristic measuring section that transmits transfer characteristic information indicating a measured transfer characteristic to the central control device; a storage section that stores control parameters transmitted from the central control device; and the electrical characteristic value measured by the measuring section. and an output control section that controls the output of the power conversion section based on the control parameters stored in the storage section.

According to the present invention, even if there is a change in the configuration of the DC grid, control can be quickly optimized.

FIG. 1 is a diagram showing the configuration of a power system according to an embodiment. FIG. 2 is a diagram showing the configuration of the control section shown in FIG. 1. FIG. 3 is a diagram showing the configuration of the power converter shown in FIG. 1. FIG. 4 is a diagram showing the configuration of the control section shown in FIG. 3. FIG. 5 is a diagram showing the configuration of the power conversion section shown in FIG. 3. FIG. 6 is a flowchart showing the flow of processing performed by EMS.

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments described below. Furthermore, in the description of the drawings, the same parts are given the same reference numerals as appropriate.

[Embodiment]
<Power system configuration>
FIG. 1 is a diagram showing the configuration of a power system according to an embodiment. The power system 1 includes power converters 11 to 14, power elements 21 to 24, and a bus 30. It is possible to add a power converter and a power element to the power system 1, and in FIG. 1, a power converter 15 and a power element 25 are shown as an example of a newly added power converter and a power element. Illustrated. Furthermore, the power system 1 includes an EMS (Energy Management System) 40. EMS 40 is an example of a central control device.

Power converters 11 to 13 and 15 are DC/DC converters that convert DC voltage. The power converter 14 is an AC/DC converter that converts between DC voltage and AC voltage. The power converters 11 to 15 have a function of communicating information by wire or wirelessly. The configurations and functions of the power converters 11 to 15 will be described in detail later.

Bus 30 is a DC bus in power system 1, and power converters 11 to 14 are connected to bus 30. A new power converter 15 can be connected to the bus 30. The power system 1 includes a power network including a DC grid including a bus 30, power converters 11-14, and power elements 21-24.

The power element 21 is, for example, a stationary power storage device capable of charging and discharging electric power, and is connected to the power converter 11. A stationary power storage device is an example of a permanently installed in-facility power storage device. The power converter 11 converts the voltage of the DC power supplied by the power element 21 and outputs it to the bus 30, and also converts the voltage of the DC power supplied from the bus 30 and outputs it to the power element 21 for charging. Has a function.

The power element 22 is, for example, a solar power generation device capable of generating and supplying electric power, and is connected to the power converter 12. A solar power generation device is an example of a power generation device that generates electricity using renewable energy. The power converter 12 has a function of converting the voltage of the DC power supplied by the power element 22 and outputting it to the bus 30.

The power element 23 is, for example, an on-vehicle power storage device capable of supplying, consuming, and charging electric power, and is connected to the power converter 13. The on-vehicle power storage device is installed in an electric vehicle EV, and is an example of a moving, non-stationary power storage device. The power converter 13 converts the voltage of the DC power supplied by the power element 23 and outputs it to the bus 30, and also converts the voltage of the DC power supplied from the bus 30 and outputs it to the power element 23 for charging. Has a function. The power converter 13 is provided, for example, in a charging station or a residential charging facility, but may also be installed in an electric vehicle EV.

The power element 24 is, for example, a commercial power system, and is connected to the power converter 14. The power converter 14 converts the AC power supplied by the power element 24 into DC power and outputs it to the bus 30 , and also converts the DC power supplied from the bus 30 into AC power and outputs it to the power element 24 . The output of power from bus 30 to power element 24 is also referred to as reverse power flow.

The power element 25 is, for example, a ZEH (Net Zero Energy House) capable of supplying, consuming, and charging electric power, and is connected to the power converter 15. The ZEH includes, for example, a solar power generation device, a storage battery, and electric appliances such as an air conditioner and a refrigerator that are power loads. The power converter 15 converts the voltage of the DC power supplied by the power element 25 and outputs it to the bus 30, converts the voltage of the DC power supplied from the bus 30 and outputs it to the power element 25, and converts the voltage of the DC power supplied from the bus 30 and outputs it to the power element 25. It has the function of charging and operating power loads.

The EMS 40 has a function of managing the power system 1 in an integrated manner. The EMS 40 includes a control section 41, a storage section 42, and a communication section 43.

The control unit 41 performs various calculation processes to realize the functions of the EMS 40, and includes, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a DSP (Digital It is configured to include processors such as Signal Processor) and GPU (Graphics Processing Unit). The functions of the control section 41 are realized as a functional section by the control section 41 reading various programs from the storage section 42 and executing them.

The storage unit 42 includes, for example, a ROM (Read Only Memory) in which various programs and data used by the control unit 41 to perform calculation processing are stored. The storage unit 42 also includes, for example, a RAM (Random Access Memory), which is used for storing a work space when the control unit 41 performs arithmetic processing, the results of the arithmetic processing by the control unit 41, and the like. There is. The storage unit 42 may include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

The communication unit 43 includes a communication module that performs wired or wireless information communication. The communication unit 43 performs information communication with the power converters 11, 12, 13, and 14 via a network NW composed of an Internet line network, a mobile phone line network, and the like. Note that the communication unit 43 also performs information communication with the power converter 15 when the power converter 15 is newly connected to the bus 30.

FIG. 2 is a diagram mainly showing the configuration of the functions of the control section 41 according to the present invention. The control unit 41 includes a command unit 41a, a characteristic acquisition unit 41b, and a setting unit 41c, which are functional units implemented in software by executing a program. The command unit 41a transmits an output command to the selected power converter, and transmits a measurement command to a power converter other than the destination of the output command. The characteristic acquisition unit 41b acquires transfer characteristic information transmitted from the power converter that has received the measurement command. The setting unit 41c sets control parameters based on the acquired transfer characteristic information, and transmits the set control parameters to the power converter.

<Configuration of power converter>
Next, a specific configuration of the power converter 11 will be explained. FIG. 3 is a diagram showing the configuration of the power converter 11. The power converter 11 includes a power conversion section 100a, a sensor 100b, a control section 100c, and a communication section 100d.

The power conversion unit 100a performs DC/DC conversion to convert the voltage of DC power input from the discharging power element 21 and output it to the bus 30. The power conversion unit 100a can also convert the voltage of the DC power input from the bus 30 and output it to the power element 21 to charge the power element 21. The power converter 100a is configured of an electric circuit including, for example, a coil, a capacitor, a diode, a switching element, and the like. The switching element is, for example, a field effect transistor or an insulated gate bipolar transistor. The power conversion unit 100a can control power conversion characteristics by, for example, PWM (Pulse Width Modulation) control.

The sensor 100b measures the electrical characteristic value of the power on the bus 30 side of the power converter 100a. Therefore, the sensor 100b measures the electrical characteristic value of the power input to or output from the power converter 11. The sensor 100b can measure current values, voltage values, power values, and the like. The sensor 100b is an example of a measuring section. The sensor 100b outputs the measured value of the electrical characteristic value to the control unit 100c.

The communication unit 100d includes a communication module that performs wired or wireless information communication, and a communication control unit that controls the operation of the communication module. The communication unit 100d communicates information with the EMS 40 via the network NW. The communication unit 100d receives information and commands from the EMS 40, for example, and outputs them to the control unit 100c. Further, the communication unit 100d transmits to the EMS 40, for example, information input from the control unit 100c and information required for connection of communication with the EMS 40.

The control unit 100c is configured to include a processor and a storage unit that perform processing for communicating with the EMS 40 and various arithmetic processing for controlling the operation of the power conversion unit 100a. As the processor and the storage section, the configurations illustrated as the configurations of the control section 41 and the storage section 42 can be used, respectively. The functions of the control unit 100c are realized as a functional unit by the processor reading various programs from the storage unit and executing them.

FIG. 4 is a diagram showing functional units according to the present invention realized in the control unit 100c. The control unit 100c includes a manipulated variable setting unit 100ca, which is a functional unit implemented in software by executing a program, a storage unit 100cb, a signal output unit 100cc, and a characteristic measurement unit 100cd.

In response to the command sent from the EMS 40, the signal output unit 100cc outputs a command to output an investigation signal for learning the transfer characteristics of the bus 30 to the power conversion unit 100a, and causes the power conversion unit 100a to output the investigation signal.

The manipulated variable setting unit 100ca, which is an example of an output control unit, sets the manipulated variable (for example, duty ratio) for PWM control so that the difference between the measurement result by the sensor 100b and the target value is within a predetermined range. Performs feedback control. The target value is, for example, a voltage value or a power value. The operation amount setting section 100ca outputs information on the set operation amount to the power conversion section 100a, and controls the power conversion section 100a. The feedback control performed by the manipulated variable setting unit 100ca uses a known method such as PID control, which is executed by reading control parameters such as proportional gain, integral time, and differential time stored in the storage unit 100cb from the storage unit 100cb. It can be executed by

The characteristic measurement unit 100cd acquires from the sensor 100b changes in the measured values of the voltage and current of the bus 30 in response to the investigation signals output from other power converters, and measures them as transfer characteristics in accordance with the measurement command sent from the EMS 40. do. The characteristic measurement unit 100cd transmits information indicating the measured transfer characteristic to the EMS 40.

FIG. 5 is a block diagram showing the configuration of the power conversion section 100a. The power conversion unit 100a includes firmware 100aa, a PWM unit 100ab, and a switching unit 100ac. The firmware 100aa, the PWM section 100ab, and the switching section 100ac are examples of a signal output section. The firmware 100aa acquires the manipulated variable sent from the control section 100c, and outputs duty ratio information corresponding to the acquired manipulated variable to the PWM section 100ab. PWM section 100ab outputs a PWM signal with a duty ratio output from firmware 100aa to switching section 100ac. The switching unit 100ac performs a switching operation according to the PWM signal output from the PWM unit 100ab, and performs an output according to the operation amount. Further, the firmware 100aa acquires the output command sent from the control unit 100c, and sets the duty ratio and cycle of the PWM signal output from the PWM unit 100ab so that the investigation signal is output to the bus 30. The investigation signal output from the switching unit 100ac is, for example, a step signal. Note that the investigation signal is not limited to a step signal, and may be an impulse signal, a sweep signal, or a spread code.

Note that the other power converters 12, 13, 14, and 15 may have the same configuration as the power converter 11. However, the power converter 100a of the power converter 14 performs an AC/DC conversion that converts the AC power supplied from the power element 24 into DC power and outputs it to the bus 30, and converts the DC power supplied from the bus 30 into AC power. DC/AC conversion is performed to convert it into electric power and output it to the power element 24.

<Operation example>
Next, an example of the operation according to the present invention will be described. When the power converter 15 is newly connected to the bus 30, for example, the power converter 15 is set to enable communication with the EMS 40, and communication with the EMS 40 becomes possible. The EMS 40 registers the power converter 15 that is newly capable of communication as a power converter included in the DC grid.

The EMS 40 performs a process of acquiring the transfer characteristics of the bus 30 at predetermined intervals. FIG. 6 is a flowchart showing the flow of processing for acquiring transfer characteristics. Specifically, the EMS 40 starts the process shown in FIG. 6 on the power converters connected to the bus 30, selects one power converter that has not yet output the investigation signal, and conducts the investigation on the selected power converter. A signal output command is transmitted (step S101). For example, the EMS 40 first selects the power converter 11 and transmits an output command. Next, the EMS 40 transmits a transfer characteristic measurement command to a power converter other than the destination of the output command (step S102). For example, when the EMS 40 transmits an output command to the power converter 11 in step S101, it transmits a measurement command to the power converters 12 to 15.

In the power converter that has received the output command, the signal output section 100cc outputs the output command to the power conversion section 100a. Power converter 100a outputs a survey signal to bus 30 in response to the output command. The power converter that has received the measurement command sends the output command to the characteristic measuring section 100cd. The characteristic measuring unit 100cd to which the output command has been sent measures changes in the measured values of the voltage and current of the bus 30 in response to the investigation signal measured by the sensor 100b as a transfer characteristic. Note that the output of the investigation signal in the power converter that has received the output command and the measurement of the transfer characteristic in the power converter that has received the measurement command are performed in synchronization, for example, by time synchronization. The power converter that has measured the transfer characteristic transmits transfer characteristic information indicating the transfer characteristic to the EMS 40. The transfer characteristic information includes information indicating the power converter that has transmitted the transfer characteristic information in order to identify the power converter that has transmitted the transfer characteristic information.

For example, when power converter 11 receives an output command and power converters 12 to 15 receive a measurement command, power converter 11 outputs a survey signal and power converters 12 to 15 measure the transfer characteristics. and transmits the transfer characteristic information to the EMS 40.

The EMS 40 receives transfer characteristic information transmitted from the power converter to which the measurement command is transmitted (step S103). The EMS 40 stores the received transfer characteristic information in association with the destination of the output command (step S104). The EMS 40, which has received the transfer characteristic information from all the power converters to which the measurement command has been transmitted, determines whether the output command has been transmitted to all the power converters connected to the bus 30 (step S105). If there is a power converter that has not been selected in step S101 and the output command has not been sent to all the power converters (No in step S105), the EMS 40 returns the process flow to step S101, and steps S101 to S105 Repeat the process.

For example, by repeating this, the EMS 40 transmits an output command in the order of power converter 12, power converter 13, power converter 14, and power converter 15, and sends a measurement command to the power converter other than the destination of the output command. Send. Every time the EMS 40 transmits an output command, it stores the received transfer characteristic information in association with the destination of the output command.

When the EMS 40 finishes transmitting the output command to all power converters (YES in step S105), it sets control parameters for PID control in the power converters 11 to 15 based on the stored transfer characteristics (step S106). . For example, regarding the transfer characteristic information stored in association with the destination of the output command, if the transfer characteristic indicated by the transfer characteristic information is the same or within a predetermined range even if the destination of the output command is different, the EMS 40 Control parameters for proportional control, differential control, and integral control in PID control of power converters 11 to 15 are set so as to achieve target transfer characteristics. Furthermore, regarding the transfer characteristic information stored in association with the destination of the output command, if the transfer characteristic indicated by the transfer characteristic information differs depending on the destination of the output command, the EMS 40 sets control parameters that emphasize the stability of the bus 30. Set. Note that when an impulse signal, a sweep signal, or a spreading code is output as the investigation signal, control parameters are set according to the measurement results of the transfer characteristics corresponding to each signal.

After setting the control parameters for PID control, the EMS 40 transmits the set control parameters to the power converters 11 to 15 (step S107). The power converters 11 to 15 store the transmitted control parameters in the storage section 100cb, and the manipulated variable setting section 100ca outputs the manipulated variable according to the stored control parameter to the power converter 100a. The power conversion unit 100a performs feedback control according to the manipulated variable output from the manipulated variable setting unit 100ca.

Next, the EMS 40 checks whether there is any abnormality in the bus 30 based on the transfer characteristic information stored in step S104 (step S108). For example, the EMS 40 stores transfer characteristic information when there is an abnormality regarding multiple types of abnormalities in the bus 30, and if the stored transfer characteristic information matches the transfer characteristic information when there is an abnormality, the abnormality is detected. Notify the system administrator of something. Examples of the types of abnormality include a poor connection of the power converter to the bus 30, a disconnection of the bus 30, and an increase in the resistance value of the bus 30 due to aging.

According to this embodiment, even if a power converter 15 is newly connected to the bus 30 and the configuration of the DC grid changes, PID control is performed in each of the power converters 11 to 15 connected to the bus 30. Since the parameters are updated and PID control is performed according to the changed transfer characteristics of the DC grid, each of the power converters 11 to 15 can perform optimal control on the bus 30. In the power system 1, the power converters 11 to 15 perform optimal control, thereby suppressing the occurrence of control failures and control failures and improving the safety of the entire system. Further, according to the present embodiment, an abnormality in the bus 30 can be detected by measuring the transfer characteristics, so that the safety of the entire system can be improved.

Note that the EMS 40 may charge and discharge the power elements 21 to 25 in the power system 1 based on the measured transfer characteristics. For example, when charging the power element 25, the transfer characteristic measured by the power converter 15 when the investigation signal is output from the power converter 11, and the transfer characteristic measured by the power converter 15 when the investigation signal is output from the power converter 13, If the transmission loss from the power converter 11 to the power converter 15 is larger than the transmission loss from the power converter 13 to the power converter 15, the power converter 13 has a lower transmission loss. The charging power may be used interchangeably by discharging the battery. In this case, the EMS 40 sets a target value as a control parameter for the manipulated variable setting unit 100ca in accordance with power interchange, and transmits the set target value to the power converters 11 to 15. In the power converters 11 to 15, the manipulated variable setting section 100ca sets the manipulated variable according to the transmitted target value, and controls the output of the power converting section 100a. According to such a configuration, power can be supplied to the power elements through a route suitable for power interchange.

[Modified example]
Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and can be implemented in various other forms. For example, the above-described embodiment may be modified as follows to implement the present invention. Note that the above-described embodiment and the following modifications may be combined. The present invention also includes configurations in which the constituent elements of each embodiment and each modification example described above are combined as appropriate. Moreover, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments and modifications, and various changes are possible.

In the present invention, the firmware 100aa sets the duty ratio and cycle of the PWM signal output from the PWM section 100ab so that the investigation signal is output to the bus 30, but the configuration for outputting the investigation signal is It is not limited to the configuration of the form. For example, a PWM signal that generates a survey signal may be supplied from the control section 100c to the switching section 100ac. Alternatively, a device that outputs the survey signal may be provided outside the power conversion unit 100a, and the device that outputs the survey signal may output the survey signal to the bus 30 in response to an output command output from the control unit 100c.

In the embodiment described above, the EMS 40 executes the process shown in FIG. 6 at a predetermined period, but the EMS 40 executes the process shown in FIG. 6 when a new power converter is connected to the bus 30. Alternatively, the control parameters may be updated. Further, in the present invention, the EMS 40 may execute the process shown in FIG. 6 and update the control parameters even when any of the power converters 11 to 15 is removed from the bus 30.

1 Power system 11, 12, 13, 14, 15 Power converter 21, 22, 23, 24, 25 Power element 30 Bus 40 EMS
100a Power conversion section 100aa Firmware 100ab PWM section 100ac Switching section 100b Sensor 100c, 41 Control section 100ca Manipulated amount setting section 100cb, 42 Storage section 100cc Signal output section 100d, 43 Communication section NW Network

Claims (4)

a DC power conversion unit that is connected to a DC bus and converts input power and outputs it;
a signal output unit that outputs a survey signal to the bus in response to an output command transmitted from a central control device;
a measurement unit that measures electrical characteristic values of the bus;
a characteristic measuring unit that measures the transfer characteristic of the bus with respect to the investigation signal in response to a measurement command transmitted from the central control device, and transmits transfer characteristic information indicating the measured transfer characteristic to the central control device;
a storage unit that stores control parameters transmitted from the central control device;
an output control unit that controls the output of the power conversion unit based on the electrical characteristic value measured by the measurement unit and the control parameter stored in the storage unit;
a plurality of power converters having;
a bus to which the plurality of power converters are connected;
a command unit that transmits an output command to the selected power converter and transmits a measurement command to the power converter other than the destination of the output command;
a characteristic acquisition unit that acquires transfer characteristic information transmitted from the power converter that has received the measurement command;
a setting unit that sets the control parameters based on the transfer characteristic information and transmits the set control parameters to the power converter;
a central control unit having;
A power system equipped with The power system according to claim 1, wherein the central control device detects an abnormality in the bus based on the transfer characteristic information. The setting unit selects a power converter to which power is to be accommodated based on the transfer characteristic information, and sets control parameters of the power converter so that power is accommodated from the selected power converter. Power system as described. a DC power conversion unit that is connected to a DC bus and converts input power and outputs it;
a signal output unit that outputs a survey signal to the bus in response to an output command transmitted from a central control device;
a measurement unit that measures electrical characteristic values of the bus;
a characteristic measuring unit that measures the transfer characteristic of the bus with respect to the investigation signal in response to a measurement command transmitted from the central control device, and transmits transfer characteristic information indicating the measured transfer characteristic to the central control device;
a storage unit that stores control parameters transmitted from the central control device;
an output control unit that controls the output of the power conversion unit based on the electrical characteristic value measured by the measurement unit and the control parameter stored in the storage unit;
A power converter comprising:

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