Power Systems and Power Converters

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

[Technical Field]

[0001] The present invention relates to power systems and power converters. [Background technology]

[0002] As an alternative to large-scale power networks that rely on fossil and nuclear energy, power networks that use locally produced and consumed electricity are attracting attention. In power networks that use locally produced and consumed electricity, a wide variety of devices, such as photovoltaic (PV) power generation devices that generate electricity using renewable energy, stationary energy storage devices, and electric vehicles (EVs), are connected to a DC bus via DC / DC converters. As these devices use DC power sources, studies are underway to optimize the direct current (DC) power network (DC grid).

[0003] Methods for optimizing DC grid control include those disclosed in, for example, Non-Patent Documents 1 and 2. These methods derive an equivalent circuit of the DC grid and use a root locus-based parameter design approach or a stability assessment method using a Nyquist diagram, and perform control design for DC / DC converters connected to each device through static analysis of the DC grid. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 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 [Non-patent document 2] 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 Summary of the Invention [Problem to be solved by the invention]

[0005] In a DC grid, the number of DC / DC converters connected to the DC bus may change due to addition or removal, which may result in a change in the configuration. When the DC grid configuration changes in this way, the methods described in Non-Patent Documents 1 and 2 require a new equivalent circuit to be derived in accordance with the change in configuration and then the control design of the DC / DC converters must be performed using the derived equivalent circuit. This requires time for the control design, making it difficult to quickly respond to the optimization of the DC / DC converter control.

[0006] The present invention has been made in view of the above, and has an object to provide a technique that enables rapid optimization of control even when the configuration of a DC grid is changed. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, a power system according to one aspect of the present invention includes a DC power conversion unit connected to a DC bus and converting and outputting input power, a signal output unit outputting an inspection signal to the bus in response to an output command transmitted from a central control device, a measurement unit measuring an electrical characteristic value of the bus, a characteristic measurement unit measuring a transfer characteristic of the bus in response to the inspection signal in response to a measurement command transmitted from the central control device and transmitting transfer characteristic information indicating the measured transfer characteristic to the central control device, a storage unit storing control parameters transmitted from the central control device, and a storage unit storing the control parameters measured by the measurement unit. and a central control device having: a plurality of power converters each having an output control unit that controls the output of the power conversion unit based on the electrical characteristic values ​​determined and the control parameters stored in the memory unit; a bus to which the plurality of power converters are connected; a command unit that sends an output command to a selected power converter and sends a measurement command to power converters other than the destination of the output command; a characteristic acquisition unit that acquires transfer characteristic information sent from the power converter that has received the measurement command; and a setting unit that sets the control parameters based on the transfer characteristic information and sends the set control parameters to the power converters.

[0008] 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.

[0009] In a power system according to one aspect of the present invention, the setting unit may select a power converter from which to transfer power based on the transfer characteristic information, and set control parameters of the selected power converter so that power is transferred from the selected power converter.

[0010] A power converter according to one embodiment of the present invention comprises a DC power conversion unit connected to a DC bus for converting and outputting input power; a signal output unit for outputting an inspection signal to the bus in response to an output command sent from a central control unit; a measurement unit for measuring electrical characteristic values ​​of the bus; a characteristic measurement unit for measuring the transfer characteristics of the bus in response to the inspection signal in response to a measurement command sent from the central control unit and sending transfer characteristic information indicating the measured transfer characteristics to the central control unit; a memory unit for storing control parameters sent from the central control unit; and an output control unit for controlling the output of the power conversion unit based on the electrical characteristic values ​​measured by the measurement unit and the control parameters stored in the memory unit. [Effects of the Invention]

[0011] According to the present invention, even if the configuration of the DC grid is changed, control can be quickly optimized. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the configuration of a power system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of the control unit illustrated in FIG. [Figure 3] FIG. 3 is a diagram illustrating a configuration of the power converter illustrated in FIG. [Figure 4] FIG. 4 is a diagram illustrating a configuration of the control unit illustrated in FIG. [Figure 5] FIG. 5 is a diagram illustrating a configuration of the power conversion unit illustrated in FIG. [Figure 6] FIG. 6 is a flowchart showing the flow of processing performed by the EMS. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment described below. Furthermore, in the description of the drawings, the same parts are appropriately designated by the same reference numerals.

[0014] [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 11-14, power elements 21-24, and a bus 30. Power converters and power elements can be added to the power system 1, and FIG. 1 illustrates a power converter 15 and a power element 25 as examples of a newly added power converter and power element. The power system 1 also includes an EMS (Energy Management System) 40. The EMS 40 is an example of a central control device.

[0015] Power converters 11-13 and 15 are DC / DC converters that convert DC voltage. Power converter 14 is an AC / DC converter that converts DC voltage to AC voltage. Power converters 11-15 have the function of performing wired or wireless information communication. The configurations and functions of power converters 11-15 will be described in detail later.

[0016] Bus 30 is a DC bus in power system 1, and power converters 11 to 14 are connected to it. A new power converter 15 can be connected to bus 30. Power system 1 configures a power network including a DC grid made up of bus 30, power converters 11 to 14, and power elements 21 to 24.

[0017] As an example, the power element 21 is a stationary power storage device capable of charging and discharging power, and is connected to the power converter 11. The stationary power storage device is an example of a permanently installed in-facility power storage device. The power converter 11 has the function of converting the voltage of the DC power supplied by the power element 21 and outputting it to the bus 30, and also converting the voltage of the DC power supplied from the bus 30 and outputting it to the power element 21, causing it to be charged.

[0018] One example of the power element 22 is a solar power generation device capable of generating and supplying electric power, and is connected to the power converter 12. The solar power generation device is an example of a power generation device that generates electric power 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.

[0019] Power element 23 is, for example, an on-board power storage device capable of supplying, consuming, and charging power, and is connected to power converter 13. The on-board power storage device is mounted on an electric vehicle EV and is an example of a mobile, non-stationary power storage device. Power converter 13 has the function of converting the voltage of DC power supplied by power element 23 and outputting it to bus 30, and also converting the voltage of DC power supplied from bus 30 and outputting it to power element 23 for charging. Power converter 13 is provided, for example, in a charging station or residential charging equipment, but may also be mounted on the electric vehicle EV.

[0020] As an example, the power element 24 is 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 the bus 30 to the power element 24 is also called reverse power flow.

[0021] One example of power element 25 is a Net Zero Energy House (ZEH) that can supply, consume, and charge power, and is connected to power converter 15. The ZEH has, for example, a solar power generation device, a storage battery, and electrical appliances such as an air conditioner and a refrigerator as power loads. Power converter 15 has the function of converting the voltage of DC power supplied by power element 25 and outputting it to bus 30, and also converting the voltage of DC power supplied from bus 30 and outputting it to power element 25, charging the storage battery, and operating the power load.

[0022] The EMS 40 has a function of comprehensively managing the power system 1. The EMS 40 includes a control unit 41, a storage unit 42, and a communication unit 43.

[0023] The control unit 41 performs various arithmetic processing to realize the functions of the EMS 40, and is configured to include processors such as a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit). The functions of the control unit 41 are realized as functional units by the control unit 41 reading and executing various programs from the storage unit 42.

[0024] The storage unit 42 includes, for example, a ROM (Read Only Memory) that stores various programs and data used by the control unit 41 to perform arithmetic processing. The storage unit 42 also includes, for example, a RAM (Random Access Memory) that is used as a workspace when the control unit 41 performs arithmetic processing and for storing the results of the arithmetic processing of the control unit 41. The storage unit 42 may also include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0025] The communication unit 43 includes a communication module that performs information communication via wire or wirelessly. The communication unit 43 performs information communication with the power converters 11, 12, 13, and 14 via a network NW that is configured from an internet network, a mobile phone network, etc. When the power converter 15 is newly connected to the bus 30, the communication unit 43 also performs information communication with the power converter 15.

[0026] 2 is a diagram showing the configuration of the control unit 41, mainly the functions related to the present invention. The control unit 41 has a command unit 41a, a characteristic acquisition unit 41b, and a setting unit 41c, which are functional units realized in software by executing a program. The command unit 41a sends an output command to a selected power converter and sends a measurement command to power converters other than the destination of the output command. The characteristic acquisition unit 41b acquires transfer characteristic information sent from the power converter that 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.

[0027] <Power converter configuration> Next, a specific configuration of the power converter 11 will be described. Fig. 3 is a diagram showing the configuration of the power converter 11. The power converter 11 has a power conversion unit 100a, a sensor 100b, a control unit 100c, and a communication unit 100d.

[0028] The power conversion unit 100a performs DC / DC conversion, converting the voltage of DC power input from the discharging power element 21 and outputting the converted voltage to the bus 30. The power conversion unit 100a can also convert the voltage of DC power input from the bus 30 and output the converted voltage to the power element 21, thereby charging the power element 21. The power conversion unit 100a is configured with 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 the power conversion characteristics by, for example, PWM (Pulse Width Modulation) control.

[0029] The sensor 100b measures the electrical characteristic value of the power on the bus 30 side of the power conversion unit 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 a current value, a voltage value, a power value, etc. The sensor 100b is an example of a measurement unit. The sensor 100b outputs the measured value of the electrical characteristic value to the control unit 100c.

[0030] The communication unit 100d includes a communication module that communicates information via a wired or wireless connection, 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, for example, information and commands from the EMS 40 and outputs them to the control unit 100c. The communication unit 100d also transmits, for example, information input from the control unit 100c and information required for establishing a communication connection with the EMS 40 to the EMS 40.

[0031] The control unit 100c includes a processor and a storage unit that perform processes for communicating with the EMS 40 and various arithmetic processes for controlling the operation of the power conversion unit 100a. The processor and storage unit may use the configurations exemplified for the control unit 41 and storage unit 42, respectively. The functions of the control unit 100c are realized as functional units by the processor reading and executing various programs from the storage unit.

[0032] 4 is a diagram showing functional units according to the present invention realized in the control unit 100c. The control unit 100c includes an operation amount setting unit 100ca, a memory unit 100cb, a signal output unit 100cc, and a characteristic measurement unit 100cd, which are functional units realized in software by executing a program.

[0033] In response to the command sent from the EMS 40, the signal output unit 100cc outputs an output command for an investigation signal to the power conversion unit 100a to determine the transfer characteristics of the bus 30, causing the power conversion unit 100a to output the investigation signal.

[0034] The manipulated variable setting unit 100ca, an example of an output control unit, performs feedback control to set a manipulated variable (e.g., duty ratio) for PWM control so that the difference between the measurement result by the sensor 100b and a target value falls within a predetermined range. The target value is, for example, a voltage value or a power value. The manipulated variable setting unit 100ca outputs information about the set manipulated variable to the power conversion unit 100a, thereby controlling the power conversion unit 100a. The feedback control performed by the manipulated variable setting unit 100ca can be performed using a known method, such as PID control, which reads control parameters such as proportional gain, integral time, and derivative time stored in the memory unit 100cb from the memory unit 100cb and executes them.

[0035] 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 an inspection signal output from another power converter, and measures them as transfer characteristics in response to a measurement command sent from the EMS 40. The characteristic measurement unit 100cd transmits information indicating the measured transfer characteristics to the EMS 40.

[0036] FIG. 5 is a block diagram showing the configuration of the power conversion unit 100a. The power conversion unit 100a includes firmware 100aa, a PWM unit 100ab, and a switching unit 100ac. The firmware 100aa, PWM unit 100ab, and switching unit 100ac are examples of a signal output unit. The firmware 100aa acquires an operation amount sent from the control unit 100c and outputs duty ratio information corresponding to the acquired operation amount to the PWM unit 100ab. The PWM unit 100ab outputs a PWM signal having the duty ratio output from the firmware 100aa to the switching unit 100ac. The switching unit 100ac performs switching operation in response to the PWM signal output from the PWM unit 100ab and outputs a signal corresponding to the operation amount. The firmware 100aa also acquires an output command sent from the control unit 100c and sets the duty ratio and period of the PWM signal output from the PWM unit 100ab so that an inspection signal is output to the bus 30. The check signal output from the switching unit 100ac is, for example, a step signal. Note that the check signal is not limited to a step signal, and may be an impulse signal, a sweep signal, or a spreading code.

[0037] The other power converters 12, 13, 14, and 15 may have the same configuration as the power converter 11. However, the power conversion unit 100a of the power converter 14 performs AC / DC conversion to convert AC power supplied from the power element 24 into DC power and output the DC power to the bus 30, and DC / AC conversion to convert DC power supplied from the bus 30 into AC power and output the AC power to the power element 24.

[0038] <Example of operation> Next, an example of an operation according to the present invention will be described. When a new power converter 15 is connected to the bus 30, for example, the power converter 15 is configured to enable communication with the EMS 40, and communication with the EMS 40 becomes possible. The EMS 40 registers the newly enabled power converter 15 as a power converter included in the DC grid.

[0039] The EMS 40 performs processing to acquire the transfer characteristics of the bus 30 at predetermined intervals. FIG. 6 is a flowchart showing the flow of the processing to acquire the transfer characteristics. Specifically, the EMS 40 selects one of the power converters connected to the bus 30 that has not yet output an investigation signal since starting the processing of FIG. 6, and transmits a command to output an investigation signal to the selected power converter (step S101). For example, the EMS 40 first selects the power converter 11 and transmits an output command to it. Next, the EMS 40 transmits a command to measure the transfer characteristics to the power converters other than the destination of the output command (step S102). For example, if the EMS 40 transmitted an output command to the power converter 11 in step S101, it transmits a measurement command to the power converters 12 to 15.

[0040] When a power converter receives an output command, the signal output unit 100cc outputs the output command to the power conversion unit 100a. The power conversion unit 100a outputs an investigation signal to the bus 30 in response to the output command. When a power converter receives a measurement command, the power converter sends the output command to the characteristic measurement unit 100cd. The characteristic measurement unit 100cd, to which the output command has been sent, measures, as transfer characteristics, 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. Note that the output of the investigation signal by the power converter that received the output command and the measurement of the transfer characteristics by the power converter that received the measurement command are performed synchronized, for example, by time synchronization. The power converter that measured the transfer characteristics transmits transfer characteristic information indicating the transfer characteristics to the EMS 40. The transfer characteristic information includes information indicating the power converter that transmitted the transfer characteristic information, in order to identify the power converter that transmitted the transfer characteristic information.

[0041] For example, when power converter 11 receives an output command and power converters 12 to 15 receive a measurement command, power converter 11 outputs an investigation signal, and power converters 12 to 15 measure the transfer characteristics and transmit the transfer characteristic information to EMS40.

[0042] The EMS 40 receives transfer characteristic information transmitted from the power converter that is the destination of the measurement command (step S103). The EMS 40 stores the received transfer characteristic information in association with the destination of the output command (step S104). After receiving the transfer characteristic information from all power converters that are the destinations of the measurement command, the EMS 40 determines whether output commands have been transmitted to all power converters connected to the bus 30 (step S105). If there is a power converter that has not been selected in step S101 and output commands have not been transmitted to all power converters (No in step S105), the EMS 40 returns the process flow to step S101 and repeats the processes of steps S101 to S105.

[0043] For example, by repeating this process, EMS 40 transmits output commands to power converters 12, 13, 14, and 15 in that order, and transmits measurement commands to power converters other than the destination of the output command. Every time EMS 40 transmits an output command, it stores the received transfer characteristic information in association with the destination of the output command.

[0044] After completing transmission of output commands to all power converters (YES in step S105), the EMS 40 sets control parameters for PID control in the power converters 11-15 based on the stored transfer characteristics (step S106). For example, when the transfer characteristics indicated by the transfer characteristic information stored in association with the destination of the output command are the same or within a predetermined range even when the destination of the output command is different, the EMS 40 sets control parameters for proportional control, differential control, and integral control in the PID control of the power converters 11-15 so that the target transfer characteristics for the DC grid are achieved. Furthermore, when the transfer characteristics indicated by the transfer characteristic information stored in association with the destination of the output command are different when the destination of the output command is different, the EMS 40 sets control parameters that prioritize stability of the bus 30. Note that when an impulse signal, a sweep signal, or a spread code is output as the investigation signal, the EMS 40 sets control parameters based on the measurement results of the transfer characteristics corresponding to each signal.

[0045] 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 unit 100cb, and the manipulated variable setting unit 100ca outputs a manipulated variable according to the stored control parameters to the power conversion unit 100a. The power conversion unit 100a performs feedback control according to the manipulated variable output from the manipulated variable setting unit 100ca.

[0046] Next, the EMS 40 checks whether or not there is an 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 for when an abnormality occurs for multiple types of abnormalities in the bus 30, and if the stored transfer characteristic information matches the transfer characteristic information for when an abnormality occurs, it notifies the system administrator that there is an abnormality. Types of abnormalities include, for example, a poor connection of the power converter to the bus 30, a broken wire in the bus 30, and an increase in the resistance value of the bus 30 due to aging.

[0047] According to this embodiment, even if a new power converter 15 is connected to the bus 30 and the configuration of the DC grid changes, the PID control parameters are updated in each of the power converters 11-15 connected to the bus 30, and PID control is performed according to the transfer characteristics of the changed DC grid, so that each of the power converters 11-15 can perform optimal control of the bus 30. Furthermore, in the power system 1, optimal control is performed in the power converters 11-15, which can reduce the occurrence of control failures and control breakdowns, improving the safety of the entire system. Furthermore, according to this embodiment, abnormalities in the bus 30 can be detected by measuring the transfer characteristics, improving the safety of the entire system.

[0048] The EMS 40 may charge and discharge the power elements 21-25 in the power system 1 based on the measured transfer characteristics. For example, when charging the power element 25, the transfer characteristics measured at the power converter 15 when the power converter 11 outputs an inspection signal may be compared with the transfer characteristics measured at the power converter 15 when the power converter 13 outputs an inspection signal. If the transmission loss from the power converter 11 to the power converter 15 is greater than the transmission loss from the power converter 13 to the power converter 15, the power converter 13 with the smaller transmission loss may be discharged to accommodate the charging power. In this case, the EMS 40 may, for example, set a target value as a control parameter for the manipulated variable setting unit 100ca in accordance with the power interchange and transmit the set target value to the power converters 11-15. The manipulated variable setting unit 100ca then sets a manipulated variable in accordance with the transmitted target value, and the power converters 11-15 control the output of the power conversion unit 100a. This configuration allows power to be supplied to the power elements via a path suitable for the power interchange.

[0049] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the above-described embodiments may be modified as follows to implement the present invention. The above-described embodiments and the following modifications may be combined with each other. The present invention also includes configurations in which the components of the above-described embodiments and modifications are appropriately combined. Furthermore, 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 modifications are possible.

[0050] In the present invention, the firmware 100aa sets the duty ratio and period of the PWM signal output from the PWM unit 100ab so that the check signal is output to the bus 30. However, the configuration for outputting the check signal is not limited to the configuration of the embodiment. For example, a PWM signal that generates the check signal may be supplied from the control unit 100c to the switching unit 100ac. Alternatively, a device that outputs the check signal may be provided outside the power conversion unit 100a, and the device that outputs the check signal may output the check signal to the bus 30 in response to an output command output from the control unit 100c.

[0051] In the above-described embodiment, the EMS 40 executes the process shown in Fig. 6 at a predetermined cycle, but the EMS 40 may execute the process shown in Fig. 6 and update the control parameters when a new power converter is connected to the bus 30. Furthermore, in the present invention, the EMS 40 may also execute the process shown in Fig. 6 and update the control parameters when any of the power converters 11 to 15 is removed from the bus 30. [Explanation of symbols]

[0052] 1. Power System 11, 12, 13, 14, 15 Power converter 21, 22, 23, 24, 25 Power elements 30 Bus 40 EMS 100a power conversion unit 100aa firmware 100ab PWM section 100ac switching section 100b sensor 100c, 41 control section 100ca operation amount setting section 100cb, 42 storage units 100cc signal output section 100d, 43 Communications Department NW Network

Claims

1. a DC power conversion unit connected to the DC bus and converting and outputting input power; a signal output unit that outputs an inspection signal to the bus in response to an output command sent from a central control device; a measurement unit for measuring an electrical characteristic value of the bus; a characteristic measurement unit that measures the transfer characteristic of the bus in response to the investigation signal in response to a measurement command transmitted from the central control unit, and transmits transfer characteristic information indicating the measured transfer characteristic to the central control unit; a storage unit for storing control parameters transmitted from the central control device; an output control unit that controls an output of the power conversion unit based on the electrical characteristic value measured by the measurement unit and a 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 converters 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 A power system comprising:

2. The central control device detects an abnormality in the bus based on the transfer characteristic information. The power system of claim 1 .

3. The setting unit selects a power converter from which power is to be transferred based on the transfer characteristic information, and sets control parameters of the selected power converter so that power is transferred from the selected power converter. The power system of claim 1 .

4. a DC power conversion unit connected to the DC bus and converting and outputting input power; a signal output unit that outputs an investigation signal to the bus in response to an output command transmitted from a central control device that transmits an output command to a selected power converter, transmits a measurement command to power converters other than the destination of the output command, acquires transfer characteristic information transmitted from the power converter that received the measurement command, sets control parameters based on the transfer characteristic information, and transmits the set control parameters to the power converters; a measurement unit for measuring an electrical characteristic value of the bus; a characteristic measurement unit that measures the transfer characteristic of the bus in response to the investigation signal in response to a measurement command transmitted from the central control unit, and transmits transfer characteristic information indicating the measured transfer characteristic to the central control unit; a storage unit for storing control parameters transmitted from the central control device; an output control unit that controls an output of the power conversion unit based on the electrical characteristic value measured by the measurement unit and a control parameter stored in the storage unit; A power converter comprising:

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