Power converter, power system, method for controlling power converter, and program

Abstract

This power converter is provided with: a power conversion unit which is connected to a bus line to which a first power converter of a power grid and a second power converter of a device for generating power using renewable energy are connected, and which is connected to a chargeable / dischargeable power unit; a measurement unit that measures an electrical characteristic value of the bus line; a setting unit that sets the characteristics of the power conversion unit by means of the electrical characteristic value and a first reference function that defines a target electrical characteristic value in accordance with the electrical characteristic value; and a management unit that manages a renewable energy charge amount, which is the charge amount of the second power converter, by means of a second reference function that defines a target electrical characteristic value of the first power converter in accordance with an electrical characteristic value measured by the first power converter, and an electrical characteristic value when power is supplied from the bus line. The amount of power supplied from the power unit from the renewable energy source is managed on the basis of an electrical characteristic value measured when power is supplied to the bus and the amount of charge of the renewable energy source.

Description

Technical Field

[0001] The present invention relates to a power converter, a power system, a control method for a power converter, and a program. Background Art

[0002] As an alternative to large-scale power grids that rely on fossil fuels and nuclear energy, power grids that use locally generated and consumed electricity have attracted attention. A variety of devices such as solar power generation devices (PhotoVoltaic (PV)), stationary energy storage devices, and electric vehicles (EV) are connected to a power grid that uses locally generated and consumed electricity. These devices generate electricity using renewable energy.

[0003] As an invention for managing renewable energy generated in such a power grid, for example, there is a power management system disclosed in Patent Document 1. The power supply and demand management device of this system manages the date and time when power can be supplied from power generation devices that generate power using renewable energy such as sunlight, hydropower, and wind power, and the amount of power that can be supplied. In addition, the charge and discharge system included in this system charges the regenerative power generated by renewable energy and supplies power in response to a request. When power supply is requested during a period when power is not generated by renewable energy, the power supply and demand management device requests power supply from the charge and discharge system. The charge and discharge system supplies power according to the power request.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: JP-A-2022-82194 Summary of the Invention

[0007] -Problems to be Solved by the Invention-

[0008] In a power network, power from a commercial power grid and power from renewable energy sources are mixed to charge a storage battery. However, in the system of Patent Document 1, only the renewable energy is used to charge the charge-discharge system, and charging from the commercial power grid is not considered. Therefore, there is a problem that the input of power from renewable energy sources cannot be managed for a storage battery that can be charged with both power from the commercial power grid and power from renewable energy sources. In addition, in order to reduce the environmental burden, sometimes power from renewable energy sources is requested when power is supplied from the charged storage battery. To respond to this request, it is necessary to manage how much power from renewable energy sources is supplied from the storage battery and how much the storage battery is charged as the supply occurs. However, in the system of Patent Document 1, there is a problem that the power from renewable energy sources among the power from the commercial power grid and the power from renewable energy sources that is output cannot be managed.

[0009] The present invention is proposed in view of the above, and an object thereof is to manage the input and output of power from renewable energy sources for a power unit that can be charged with both power from a commercial power grid and power from renewable energy sources.

[0010] -Means for Solving the Problem-

[0011] One embodiment of the present invention relates to a power converter, comprising: a power conversion unit connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power using renewable energy are connected, converting the power input from the bus and outputting it to a power unit capable of charging and discharging, and converting the power input from the power unit and outputting it to the bus; a measurement unit that measures electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; a storage unit that stores a first reference function that defines a target electrical characteristic value corresponding to the electrical characteristic value measured by the measurement unit and a second reference function that defines a target electrical characteristic value of the first power converter corresponding to the electrical characteristic value measured by the first power converter; a setting unit that sets the power conversion characteristics of the power conversion unit based on the electrical characteristic value determined by the first reference function corresponding to the electrical characteristic value measured by the measurement unit; and a management unit that manages the amount of charging of the power unit with renewable energy, i.e., the amount of renewable energy charging, achieved by the power from the renewable energy supplied from the second power converter to the power conversion unit based on the electrical characteristic value measured by the measurement unit and the second reference function when power is supplied from the bus to the power conversion unit, and manages the amount of power from the renewable energy supplied from the power unit based on the electrical characteristic value measured by the measurement unit and the amount of renewable energy charging when power is supplied from the power unit charged with renewable energy to the bus via the power conversion unit.

[0012] In the power converter according to one embodiment of the present invention, it may further have: an update unit that updates the first reference function corresponding to the amount of renewable energy charging.

[0013] In the power converter according to one embodiment of the present invention, the update unit may update the maximum value of the target value of the output of the power conversion unit specified by the first reference function corresponding to the amount of renewable energy charging.

[0014] In addition, in the power converter according to one embodiment of the present invention, it is also possible that the storage unit stores a reference function that defines target electrical characteristic values for each of a plurality of power converters, where the plurality of power converters convert the power input from the bus and output it to a power unit capable of charging and discharging, and convert the power input from the power unit and output it to the bus, and the management unit manages the amount of charge to the power unit, i.e., the amount of renewable energy charge, achieved by the power from renewable energy supplied from the second power converter to the power conversion unit, based on the electrical characteristic values measured by the measurement unit when supplying power from the bus to the power conversion unit, the second reference function, and the reference function for each of the plurality of power converters.

[0015] In addition, in the power converter according to one embodiment of the present invention, it is also possible that the management unit corrects the first reference function based on the voltage drop of the bus.

[0016] A power system according to one embodiment of the present invention includes: a first power converter that converts and outputs the power supplied from the power grid; a second power converter that converts and outputs the power supplied from a power generation device that generates power using renewable energy; and a DC bus to which the first power converter and the second power converter are connected. The power system includes a power converter having: a power conversion unit connected to the bus, which converts the power input from the bus and outputs it to a power unit capable of charging and discharging, and converts the power input from the power unit and outputs it to the bus; a measurement unit that measures the electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; a storage unit that stores a first reference function that defines target electrical characteristic values corresponding to the electrical characteristic values measured by the measurement unit, and a second reference function that defines the target electrical characteristic values of the first power converter corresponding to the electrical characteristic values measured by the first power converter; a setting unit that sets the power conversion characteristics of the power conversion unit based on the electrical characteristic values determined by the first reference function corresponding to the electrical characteristic values measured by the measurement unit; and a management unit that manages the amount of charge to the power unit, i.e., the amount of renewable energy charge, achieved by the power from renewable energy supplied from the second power converter to the power conversion unit, based on the electrical characteristic values measured by the measurement unit when supplying power from the bus to the power conversion unit and the second reference function, and manages the amount of power from renewable energy supplied from the power unit based on the electrical characteristic values measured by the measurement unit when supplying power from the power unit charged with power from renewable energy to the bus via the power conversion unit and the amount of renewable energy charge.

[0017] A power system according to one embodiment of the present invention may also include: a third power converter connected to the bus, requesting power from renewable energy sources to the power converter, converting the power supplied from the power converter, and outputting the converted power to the connected power unit. The third power converter reduces the output to the connected power unit in response to a decrease in the voltage of the bus.

[0018] A control method for a power converter according to one embodiment of the present invention is a control method for a power converter. The power converter includes a power conversion unit connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power from renewable energy sources are connected. The power conversion unit converts the power input from the bus and outputs it to a power unit capable of charging and discharging, and converts the power input from the power unit and outputs it to the bus. The control method of the power converter includes: a measurement step of measuring electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; a setting step of setting the power conversion characteristics of the power conversion unit based on the electrical characteristic values determined by a first reference function that defines a target electrical characteristic value corresponding to the electrical characteristic values measured in the measurement step; and a management step of managing the amount of charging of the power unit by the power from renewable energy sources supplied from the second power converter to the power conversion unit, that is, the amount of renewable energy charging, based on the electrical characteristic values measured in the measurement step when power is supplied from the bus to the power conversion unit and a second reference function that defines the target electrical characteristic value of the first power converter corresponding to the electrical characteristic values measured by the first power converter, and managing the amount of power from renewable energy sources supplied from the power unit based on the electrical characteristic values measured in the measurement step when power is supplied from the power unit charged with power from renewable energy sources to the bus via the power conversion unit and the amount of renewable energy charging.

[0019] A program according to one aspect of the present invention is executed by a processor of a power converter. The power converter has a power conversion unit, and the power conversion unit is connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power using renewable energy are connected. The power conversion unit converts the power input from the bus and outputs it to a power unit capable of charging and discharging, and converts the power input from the power unit and outputs it to the bus. The program causes the processor of the power converter to execute: a measurement step of measuring electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; a setting step of setting the power conversion characteristics of the power conversion unit based on the electrical characteristic values determined by a first reference function that defines a target electrical characteristic value corresponding to the electrical characteristic values measured in the measurement step; and a management step of managing the amount of charging of the power unit by the power from renewable energy, which is the amount of renewable energy charging, based on the electrical characteristic values measured in the measurement step when supplying power from the bus to the power conversion unit and a second reference function that defines the target electrical characteristic value of the first power converter corresponding to the electrical characteristic values measured by the first power converter, and managing the amount of power from renewable energy supplied from the power unit based on the electrical characteristic values measured in the measurement step when supplying power from the power unit charged with power from renewable energy to the bus via the power conversion unit and the amount of renewable energy charging.

[0020] -Advantages of the Invention-

[0021] According to the present invention, it is possible to manage the input and output of power from renewable energy for a power unit that can be charged using both power from a commercial power grid and power from renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. is a diagram showing the structure of a power system according to an embodiment.

[0023] Figure 2 FIG. is a diagram showing the structure of a power converter.

[0024] Figure 3 FIG. is a diagram showing the structure of a control unit of a power converter.

[0025] Figure 4 FIG. is a diagram showing the structure of a functional unit of a power converter.

[0026] Figure 5 FIG. is a diagram showing an example of a reference function.

[0027] Figure 6 It is a sequence diagram showing an example of a control method for a power system.

[0028] Figure 7 It is a flowchart showing the process performed by the control unit of the power converter.

[0029] Figure 8 It is a diagram showing an example of a reference function.

[0030] Figure 9 It is a diagram showing an example of a reference function.

[0031] Figure 10 It is a diagram showing an example of a reference function.

[0032] Figure 11 It is a diagram showing an example of a reference function.

[0033] Figure 12 It is a sequence diagram showing an example of a control method for a power system.

[0034] Figure 13 It is a diagram showing an example of a reference function.

[0035] Figure 14 It is a diagram showing the structure of the power system related to a modified example.

[0036] Figure 15 It is a diagram showing an example of a reference function. Detailed Implementation Modes

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present invention is not limited by the embodiments described below. Further, in the description of the drawings, the same parts are appropriately labeled with the same reference numerals.

[0038] [Embodiments]

[0039] [Structure of Power System]

[0040] Figure 1It is a diagram showing the structure of the power system related to the embodiment of the present invention. The power system 1 is a system that charges a storage battery using power from a commercial power grid and power from renewable energy sources, and can supply power from the charged storage battery. When charging the storage battery, the power system 1 manages the charging achieved by the power from the commercial power grid and the charging achieved by the power from renewable energy sources. When supplying power from the storage battery, the power system 1 manages the power supply from renewable energy sources and the power supply from the commercial power grid. The power system 1 includes power converters 11 to 15, power units 21 to 25, and a bus 30. Furthermore, the power system 1 includes an EMS (Energy Management System) 40. The EMS 40 is an example of a central control device.

[0041] The bus 30 is a DC bus in the power system 1 and is connected to the power converters 11 to 15. In the power system 1, a power network is formed that includes a DC grid composed of the bus 30, the power converters 11 to 15, and the power units 21 to 25.

[0042] The power converters 11 to 13, 15 are DC / DC converters that convert DC voltage. The power converter 14 is an AC / DC converter that performs the conversion between DC voltage and AC voltage. The structures and functions of the power converters 11 to 15 will be described in detail later.

[0043] As an example, the power unit 21 is a stationary energy storage device capable of charging and discharging power and is connected to the power converter 11. The stationary energy storage device is an example of a storage device within a permanent facility. The power converter 11 has the following functions: converting the voltage of the DC power supplied by the power unit 21 and outputting it to the bus 30, and converting the voltage of the DC power supplied from the bus 30 and outputting it to the power unit 21 to charge the power unit 21. The power converter 11 has a function of performing information communication via wire or wireless. The power converter 11 communicates with the EMS 40 and controls the input / output to the bus 30 based on the reference function sent from and stored in the EMS 40.

[0044] As an example, the power unit 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 unit 22 and outputting it to the bus 30. The power converter 12 is an example of a second power converter. The power converter 12 has a function of performing information communication by wire or wirelessly. The power converter 12 communicates with the EMS 40 and controls the output to the bus 30 based on the reference function sent from and stored in the EMS 40. In addition, the power unit 22 is not limited to a solar power generation device, and may also be a power generation device that generates electric power using renewable energy, such as a power generation device using hydraulic power or a power generation device using wind power.

[0045] As an example, the power unit 23 is an in-vehicle power storage device capable of supplying and charging electric power, and is connected to the power converter 13. The power unit 23 is mounted on the electric vehicle EV and is an example of a non-stationary power storage device that moves. The power converter 13 has the following functions: converting the voltage of the DC power supplied by the power unit 23 and outputting it to the bus 30, and converting the voltage of the DC power supplied from the bus 30 and outputting it to the power unit 23 so as to perform charging. The power converter 13 is an example of a third power converter. The power converter 13 is provided, for example, at a charging station for an electric vehicle or a residential charging device, but may also be mounted on the electric vehicle EV. The power converter 13 has a function of performing information communication by wire or wirelessly. The power converter 13 communicates with the EMS 40 and controls the input / output to the bus 30 based on the reference function sent from and stored in the EMS 40.

[0046] As an example, the power unit 24 is a commercial power grid and is connected to the power converter 14. The power converter 14 converts the AC power supplied by the power unit 24 into DC power and outputs it to the bus 30, and converts the DC power supplied from the bus 30 into AC power and outputs it to the power unit 24. The power converter 14 is an example of a first power converter. The output of power from the bus 30 to the power unit 24 is also called reverse power flow. The power converter 14 has a function of performing information communication by wire or wirelessly. The power converter 14 communicates with the EMS 40 and controls the input / output to the bus 30 based on the reference function sent from and stored in the EMS 40.

[0047] The power unit 25 is a power-consuming device, for example, a device that converts electrical power into kinetic energy or heat energy. The power converter 15 has the function of converting the voltage of the DC power supplied from the bus 30 and outputting it to the power unit 25 to operate the power unit 25. The power converter 15 is also an example of a third power converter. The power converter 15 has the function of information communication via wire or wireless. The power converter 15 communicates with the EMS 40 and controls the output to the power unit 25 based on the reference function sent from and stored in the EMS 40.

[0048] The EMS 40 has the function of comprehensively managing the state of the power system 1. The EMS 40 includes a control unit 41, a storage unit 42, and a communication unit 43.

[0049] The control unit 41 performs various arithmetic processes for realizing the functions of the EMS 40, and is composed of, for example, 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 out and executing various programs from the storage unit 42.

[0050] The storage unit 42 includes, for example, a ROM (Read Only Memory) for storing various programs, data, etc. used by the control unit 41 for arithmetic processes. In addition, the storage unit 42 includes, for example, a RAM (Random Access Memory) for storing the working space during the arithmetic processes of the control unit 41, the results of the arithmetic processes of the control unit 41, etc. The storage unit 42 may also include auxiliary storage devices such as an HDD (Hard Disk Drive) and an SSD (Solid State Drive).

[0051] The communication unit 43 is composed of a communication module for information communication via wire or wireless. The communication unit 43 communicates with the power converters 11 to 15 and the external server 60 via a network NW composed of an Internet line network, a mobile phone line network, etc.

[0052] In addition, the external server 60 is a server provided outside the power system 1. The external server 60 includes, for example, an information processing device and a database configured to function as an EMS in other power systems, and an information processing device that functions as a data server with respect to the EMS 40. The external server 60 stores various information that may affect the operation of the power system 1.

[0053] <Structure of the power converter>

[0054] Next, the specific structure of the power converter 11 will be described. Figure 2 FIG. is a diagram showing the structure of the power converter 11. The power converter 11 includes a control unit 100, a power conversion unit 110, a sensor 120, and a communication unit 130.

[0055] The power conversion unit 110 performs DC / DC conversion to convert the voltage of the DC power input from the discharging power unit 21 and output it to the bus 30. The power conversion unit 110 can also convert the voltage of the DC power input from the bus 30 and output it to the power unit 21 to charge the power unit 21. The power conversion unit 110 is composed of an electrical circuit including, for example, coils, capacitors, diodes, and switching elements. The switching element is, for example, a field effect transistor or an insulated gate bipolar transistor. The power conversion unit 110 can control the power conversion characteristics by PWM (Pulse Width Modulation), for example.

[0056] The sensor 120 measures the electrical characteristic values of the power on the bus 30 side of the power conversion unit 110. The sensor 120 is an example of a measurement unit. Therefore, the sensor 120 measures the electrical characteristic values of the power input to or output from the power converter 11. The sensor 120 can measure current values, voltage values, power values, etc. as the electrical characteristic values. The sensor 120 outputs the measured electrical characteristic values to the control unit 100.

[0057] The communication unit 130 includes a communication module that communicates information either wired or wirelessly. The communication unit 130 communicates information with the power converters 12 - 15 and the EMS 40 via the network NW. The communication unit 130 receives, for example, instructions sent from the EMS 40 and instructions sent from the power converters 12 - 15, and outputs them to the control unit 100, and sends the instructions output from the control unit 100 to the power converters 12 - 15. The instructions sent from the EMS 40 include reference function information. The reference function information will be described later. In addition, the communication unit 130 sends, for example, information related to the power condition input from the control unit 100 to the EMS 40. Further, when the information related to the power condition is the measured value of the sensor 120, the communication unit 130 can send, for example, the electrical characteristic value input from the sensor 120 to the EMS 40.

[0058] Figure 3 is a block diagram showing the structure of the control unit 100. The processor 101, the memory 102, the storage 103, the input / output I / F 104, and the communication I / F 105 are connected to the bus 106 to form the control unit 100. The memory 102 is, for example, a RAM, and is composed of a volatile memory or a non-volatile memory. The memory 102 becomes the working space when the processor 101 performs arithmetic processing, and stores the results of the arithmetic processing of the processor, etc. The storage 103 is composed of auxiliary storage devices such as ROM, HDD, and SSD. The storage 103 stores programs and data used for the processor 101 to perform arithmetic processing. In addition, the storage 103 stores the reference function information received by the communication unit 130. The storage 103 is an example of a storage unit. The input / output I / F 104 is connected to the power conversion unit 110, and is controlled by the processor 101 and outputs signals for controlling the power conversion unit 110. In addition, the input / output I / F 104 is connected to the sensor 120, obtains the electrical characteristic value output from the sensor 120, and outputs it to the processor 101. The communication I / F 105 is connected to the communication unit 130 and controls the communication unit 130. The processor 101 is, for example, a CPU, reads the program from the storage 103, and executes it using the memory 102 as the working space. The processor 101 can also be an ASIC, FPGA, DSP, or GPU. By the processor 101 executing the program, the functions of the power converter 11 are realized.

[0059] Figure 4 is a diagram showing the functional units related to the present invention implemented in the control unit 100. The control unit 100 includes functional units implemented software-wise by the execution of a program, namely, an operation amount setting unit 100a, a management unit 100b, an update unit 100c, and an instruction unit 100d.

[0060] The operation amount setting unit 100a sets a target value of the output of the power conversion unit 110 based on the electrical characteristic value measured by the sensor 120 and the reference function information stored in the storage 103. The operation amount setting unit 100a is an example of a setting unit. The target value is an electrical characteristic value, such as a voltage value or a power value. In addition, the operation amount setting unit 100a performs feedback control to set an operation amount (e.g., duty ratio) for PWM control so that the difference between the electrical characteristic value measured by the sensor 120 and the set target value falls within a given range. The feedback control performed by the operation amount setting unit 100a can be executed using a known method such as PID control that reads and executes parameters such as the proportional gain, integral time, and differential time pre-stored in the storage 103. The operation amount setting unit 100a outputs the information of the set operation amount to the power conversion unit 110 to control the power conversion unit 110.

[0061] The management unit 100b manages the charging amount (renewable energy charging amount) achieved by the power from renewable energy for the power unit connected to the power conversion unit 110. The update unit 100c updates the reference function used in the control of the power conversion unit 110 corresponding to the renewable energy charging amount. The instruction unit 100d sends an instruction for requesting another power converter to the other power converter via the communication unit 130.

[0062] In addition, the other power converters 12, 13, 14, 15 may also have the same structure as the power converter 11. Among them, the power conversion unit 110 of the power converter 14 performs: AC / DC conversion that converts the AC power supplied from the power unit 24 into DC power and outputs it to the bus 30; and DC / AC conversion that converts the DC power supplied from the bus 30 into AC power and outputs it to the power unit 24.

[0063] <Characteristics of the reference function>

[0064] Next, the reference function that forms the basis of the power conversion characteristics for the control unit 100 to control the power conversion unit 110 will be described. Figure 5 It is a diagram showing an example of the reference function represented by the reference function information. The reference function information is various information for determining the droop function that constitutes the reference function. In Figure 5 it, the vertical axis is the voltage V and the horizontal axis is the power P. Figure 5The reference function shown represents the relationship between the power P and the voltage V on the bus 30 side of the power conversion unit 110 of the power converter 11, that is, the V - P characteristic, and represents the power conversion characteristic of the power conversion unit 110. In addition, when the power conversion unit 110 supplies power to the bus 30, that is, when the power unit 21 is in the discharging state, the power P is positive, and when power is supplied from the bus 30, that is, when the power unit 21 is in the charging state, the power P is negative. In addition, the state where power P = 0 is a state where neither charging nor discharging is performed.

[0065] Figure 5 The reference function characterized by the line DL1 bent in the middle shown is formed by connecting a plurality of droop functions with different droop characteristics defined corresponding to intervals of input values. Specifically, the line DL1 is formed by connecting 5 droop functions with different droop characteristics, which is determined by the reference function information. The reference function information includes, for example, the coordinate information of the boundaries of the droop functions in the coordinates with the horizontal axis as P and the vertical axis as V, the intercept information of the droop functions, the information of the slope (i.e., the droop coefficient), and the information of the shape (straight line, curve, etc.).

[0066] The control unit 100 of the power converter 11 controls the power conversion characteristic of the power converter 11 to the characteristic of the reference function shown by the line DL1. That is, the control unit 100 of the power converter 11 controls the power conversion unit 110 so that the operating point defined by the values of the voltage V and the power P, which are the electrical characteristic values on the bus 30 side of the power conversion unit 110, lies on the line DL1.

[0067] In addition, as control methods executed by the control unit 100, there are droopP control and droopV control. The droopP control is a control method that determines the target value, that is, the target power value, based on the electrical characteristic value measured by the sensor 120, that is, the voltage value, and the reference function, so that the difference between the measured value of the power of the sensor 120 and the target power value is within an allowable range. The droopV control is a control method that determines the target value, that is, the target voltage value, based on the electrical characteristic value measured by the sensor 120, that is, the power value, and the reference function, so that the difference between the measured value of the voltage of the sensor 120 and the target voltage value is within an allowable range.

[0068] <Control Method>

[0069] Next, the control methods of the power converters 11 to 15 and the control method of the power system 1 will be described. In the power system 1, so-called local control in which the power converters 11 to 15 are individually and autonomously controlled in a decentralized manner, and centralized control in which the EMS 40 performs coordinated control of the power converters 11 to 15 corresponding to the power condition of the power system 1 can be executed. In addition, for example, the local control is repeatedly executed at a relatively short cycle, and the centralized control is executed at an interval longer than the cycle of the local control. The local control is also called primary control, and the centralized control is also called secondary control. These control methods are executed, for example, by a processor executing a program in each power converter or the EMS 40.

[0070] <Centralized control>

[0071] First, the centralized control will be described. In the example shown below, the EMS 40 executes centralized control by updating the reference function information used in the power converters 11 to 15 using an instruction. Updating the reference function information by an instruction means that the instruction includes reference function information related to the reference function, and a part or the whole of the reference function is updated by the instruction. The storage 103 of each of the power converters 11 to 15 stores the reference function information so that it can be updated.

[0072] For example, in the information communication between the EMS 40 and the power converters 11 to 15, the reference function information is included in the update instruction for updating the reference function. The reference function information used in this update is stored in the storage unit 42 of the EMS 40, and is appropriately read out and used by the control unit 41.

[0073] Next, with reference to Figure 6 the sequence diagram, an example of the control method of the power system 1 based on centralized control will be described. First, the EMS 40 calls the timer of its own device and starts timing (step S101). Next, the EMS 40 requests the local measurement information from the power converters 11 to 15 respectively (step S102). The so-called local measurement information is an example of information related to the power condition of the power system 1, and includes the electrical characteristic values measured by the sensors 120 of the power converters 11 to 15 and the measurement times of the electrical characteristic values.

[0074] Next, the power converters 11 to 15 send the locally measured information obtained respectively to the EMS 40 (step S103). The EMS 40 stores each locally measured information in the storage unit 42. Next, as an example of the information related to the power condition of the power system 1, the EMS 40 requests the external server 60 for various information that may affect the operation of the power system 1 (step S104). In this example, the EMS 40 requests the external server 60 for power generation / load forecast information. The power generation / load forecast information includes the forecast information of the power generation amount in the power system 1 and the load forecast information of the power, and may include information such as the season of the area where the power system 1 is set, the current weather, and the future weather forecast. In addition, when the external server 60 functions as the EMS of another power system, when there is a possibility that the operation state of the other power system affects the operation of the power system 1, the power generation / load forecast information may include the forecast information of the power generation amount in the other power system and the load forecast information of the power. Next, the external server 60 sends the power generation / load forecast information to the EMS 40 (step S105). The EMS 40 stores the power generation / load forecast information in the storage unit 42.

[0075] Next, the control unit 41 of the EMS 40 reads out the sent information, that is, the information related to the power condition of the power system 1, etc. from the storage unit 42, and performs the operation optimization calculation of the power system 1 based on it (step S106). The operation optimization calculation is performed to be applicable to various conditions. For example, the power system 1 is controlled so that the bus 30 becomes the operating point of a given voltage. In this state, based on the power generation / load forecast information, the EMS 40 anticipates that the future weather in the area where the solar power generation device, that is, the power unit 22, is set is sunny, the power generation amount increases, and based on the locally measured information obtained from the power converter 12 connected to the power unit 22, it is determined that there is a surplus in the power supply point of the power unit 22. In this case, the EMS 40 determines to update the reference function of the power converter 11 connected to the stationary energy storage device, that is, the power unit 21, so as to charge the power unit 21 at this operating point. In addition, at the same time as this update, the EMS 40 determines to update the reference function of the power converter 14 connected to the power unit 24 so as not to supply power from the commercial power grid, that is, the power unit 24. In addition, conditions can also be set from the viewpoints of peak shaving, utilization of night power, etc., so as not to exceed the contract power of the commercial power grid, that is, the power unit 24, and optimization of electricity charges, and the operation optimization calculation is performed.

[0076] Next, based on the result of the optimization calculation, the EMS 40 sets the reference function information suitable for the power converter to be updated among the power converters 11 to 15, and outputs an update instruction including the set reference function information (step S107). Next, the EMS 40 resets the timer (step S108). Next, the power converter to be updated among the power converters 11 to 15 acquires the update instruction of the reference function and updates the reference function information (step S109). The power converter that has completed the update of the reference function information executes local control (step S110).

[0077] <Local control>

[0078] Next, regarding the control method of the power converters 11 to 15 in local control, the power converter 11 will be taken as an example for explanation. In addition, in the other power converters 12 to 15, the same control method as the following explanation can also be appropriately executed.

[0079] In the control method of the power converter 11, the control unit 100 executes control steps to control the power conversion characteristics of the power converter 11, that is, the power conversion characteristics of the power conversion unit 110, based on the electrical characteristic values and the reference function information. An example of the content of this control step will be further specifically described with reference to the drawings.

[0080] Figure 7 is a flowchart showing the process performed by the control unit 100. The control unit 100 executes the Figure 7 processing shown at a predetermined cycle. First, the control unit 100 acquires the electrical characteristic values measured by the sensor 120 (step S201). Step S201 is an example of a measurement step. Next, the control unit 100 acquires the reference function information from the storage 103 (step S202).

[0081] Next, the control unit 100 sets the target value of the output of the power converter 11 (step S203). Step S203 is an example of a setting step. Here, when the control unit 100 performs droop P control, the power value of the reference function where the horizontal axis is drawn from the position of the operating point determined from the electrical characteristic values measured by the sensor 120 is set as the target value. For example, when the reference function is the Figure 5 function shown and the operating point is at the position of OP1 shown on the V - P characteristic, the control unit 100 sets the power value P1, which is the power value of the reference function where the horizontal axis is drawn from the operating point, as the target value. In addition, when the control unit 100 performs droop V control, the voltage value of the reference function where the vertical axis is drawn from the power value measured by the sensor 120 is set as the target value. For example, when the reference function is the Figure 5 function shown and the operating point is at the position of OP1 shown on the V - P characteristic, the control unit 100 sets the power value P1, which is the power value of the reference function where the horizontal axis is drawn from the operating point, as the target value. In addition, when the control unit 100 performs droop V control, the voltage value of the reference function where the vertical axis is drawn from the power value measured by the sensor 120 is set as the target value. For example, when the reference function is Figure 5The function and operating point shown are on the V-P characteristic Figure 5 When in the position of OP1 shown, the control unit 100 sets the voltage value V1 of the reference function that intersects when pulling the line along the vertical axis from the operating point as the target value.

[0082] Next, the control unit 100 sets an operation amount for PWM control so that the difference between the electrical characteristic value measured by the sensor 120 and the target value set in step S203 falls within a given range, and outputs the set operation amount to the power conversion unit 110 (step S204). Thereby, the control of the power conversion unit 110 is executed.

[0083] <Renewable Energy Management>

[0084] In the present embodiment, the power converter 11 monitors the amount of power when charging the power unit 21 with power from renewable energy and the amount of power when supplying the charged renewable energy power from the power unit 21 to the bus 30, and manages the charging amount (renewable energy charging amount) of the power unit 21 achieved by the power from renewable energy. Hereinafter, a method for managing the renewable energy charging amount will be described. In the present embodiment, the charging amount of the power unit 21 at time point t is set as P(t) [Wh], and the renewable energy charging amount is set as P RE (t) [Wh]. Further, in the present embodiment, the amount of power input / output of the power unit 21 measured by the sensor 120 from time point t - 1 to time point t is set as P IO (t) [Wh]. Additionally, P IO (t) is set as positive when charging the power unit 21 and negative when discharging the power unit 21.

[0085] First, a method for managing P RE (t) during charging of the power unit 21 will be described. Specifically, the control unit 100 of the power converter 11 acquires the reference function of the power converter 14 from the EMS 40 in advance and stores it in the storage 103. The control unit 100 of the power converter 11 manages P RE (t) using the reference function of the power converter 14 pre-stored in the storage 103.

[0086] For example, when the output of the power unit 22 is large, through centralized control, as Figure 8 shown, the reference function of the power converter 11 becomes line DL2, the reference function of the power converter 12 becomes line DL21, and the reference function of the power converter 14 becomes line DL41. When the voltage of the bus 30 measured by the sensor 120 is Figure 8In the case of Va1 as shown, since the power P of line DL2 is negative when the voltage is Va1, the power converter 11 charges the power unit 21. Here, the control unit 100 of the power converter 11 determines how to charge the power unit 21. If the control unit 100 of the power converter 11 refers to the reference function of the power converter 14 stored in the memory 103, that is, line DL41, the power P becomes negative when the voltage of the bus 30 is Va1. That is, when the voltage of the bus 30 is Va1, in the power converter 14, it is in reverse power flow, and no output is made to the bus 30. It is determined that the charging of the power unit 21 is performed only by the output from the power unit 22. In this case, the control unit 100 of the power converter 11 performs the calculation of the following formula (1) to calculate the renewable energy charging amount. In addition, the control unit 100 of the power converter 11 records the calculated renewable energy charging amount together with the calculated date and time as a history record in the memory 103.

[0087] P RE (t + 1) = P RE (t) + P IO (t) ··· (1)

[0088] Next, in the case where the output of the power unit 22 is small, through centralized control, as Figure 9 shown, the reference function of the power converter 12 becomes line DL22. Since when the voltage of the bus 30 measured by the sensor 120 is Figure 9 Va2 as shown, and the power P of line DL2 is negative when the voltage is Va2, the power converter 11 charges the power unit 21. Here, the control unit 100 of the power converter 11 determines how to charge the power unit 21. If the control unit 100 of the power converter 11 refers to the reference function of the power converter 14 stored in the memory 103, that is, line DL41, the power P becomes positive when the voltage of the bus 30 is Va2. That is, when the voltage of the bus 30 is Va2, the power converter 14 outputs to the bus 30. It is determined that the charging of the power unit 21 is performed by the output from the power unit 22 and the output from the power unit 24. In this case, the control unit 100 of the power converter 11 performs the calculation of the following formula (2) to calculate the renewable energy charging amount. In addition, the control unit 100 of the power converter 11 records the calculated renewable energy charging amount together with the calculated date and time as a history record in the memory 103.

[0089] P RE (t + 1) = P RE (t) + P IO (t) × (2 × Va2 - Vc - Vb) / (Va2 - Vc) ··· (2)

[0090] Next, a method for managing P(t) when the power converter 13 requests power from renewable energy will be described. For example, when the output of the power unit 22 is large, as shown in RE , the reference function of the power converter 11 becomes the line DL11, the reference function of the power converter 12 becomes the line DL21, and the reference function of the power converter 13 becomes the line DL31. Since the voltage of the bus 30 measured by the sensor 120 is Figure 10 Va3 as shown in Figure 10 , and the power P of the line DL11 is negative when the voltage is Va3, the control unit 100 of the power converter 11 supplies power to the power unit 21 to charge the power unit 21. In this case, the control unit 100 of the power converter 11 performs the calculation of the formula (1) described above. In addition, the control unit 100 of the power converter 11 records the calculated renewable energy charging amount and the calculated date and time as a history in the storage 103. In addition, for the power converter 13 that has requested power from renewable energy, the requested power is compensated by the power supply from the power unit 21.

[0091] Next, for example, when the output of the power unit 22 is small, as shown in Figure 11 , the reference function of the power converter 11 becomes the line DL11, the reference function of the power converter 12 becomes the line DL23, and the reference function of the power converter 13 becomes the line DL31. Since the voltage of the bus 30 measured by the sensor 120 is Figure 11 Va4 as shown in IO , and the power P of the line DL11 is positive when the voltage is Va4, the control unit 100 of the power converter 11 supplies the power from the power unit 21 to the bus 30. In addition, the control unit 100 of the power converter 11 calculates the renewable energy charging amount by the formula (1). Here, since the power unit 21 supplies power and P(t) in the formula (1) is negative, the renewable energy charging amount continuously decreases with the continuation of the power supply. The control unit 100 of the power converter 11 records the calculated renewable energy charging amount and the calculated date and time as a history in the storage 103. In addition, when the power converter 11 requests power from renewable energy from the power converters 13 and 15 and P(t)=0, the control unit 100 of the power converter 11 performs the calculation of the formula (3) to calculate the charging amount of the power unit 21. RE P(t + 1)=P(t)+P(t) ··· (3)

[0092] P(t + 1)=P(t)+P IO (t)･･･(3)

[0093] In addition, when power from renewable energy is not requested from the power converters 13 and 15 and P(t) is not 0, the control unit 100 of the power converter 11 performs the calculation of the formula (3). When power from renewable energy is not requested from the power converters 13 and 15 and P(t) = 0, the control unit 100 of the power converter 11 performs the calculation of the formula (1), and records the calculated renewable energy charge amount and the calculated date and time together as a history in the storage 103.

[0094] In addition, in Figure 10 , Figure 11 the illustration of the reference function of the power converter 15 is omitted, but since the power unit 25 is a power-consuming device, the reference function of the power converter 15 is the same reference function as the line DL31.

[0095] <Power supply from renewable energy>

[0096] Next, an operation example when power is supplied from the power unit 21 charged with power from renewable energy is described. Figure 12 FIG. is a sequence diagram showing an example of a control method of the power system 1. For example, when the power converter 13 charges the power unit 23 with power from renewable energy, the power converter 13 sends a request command for requesting power from renewable energy to the power converters 11, 12, and 14 (steps S301 to S303). In addition, the power converter that sends the request command is not limited to the power converter 13, and the request command may be sent by the power converter 15, or may be sent by both the power converter 13 and the power converter 15. In addition, the request command may be sent by the EMS 40 instead of the power converter 13.

[0097] The power converter 13 that has sent the request command changes the reference function referred to in the local control to the reference function used when requesting the supply of power from renewable energy (step S304). Each of the power converters 11, 12, and 14 that has received the request command changes the reference function referred to in the local control to the reference function used when requesting the supply of power from renewable energy (steps S305 to S307). Then, the power converters 11 to 14 each start the local control using the changed reference function (steps S308 to S311). In addition, the reference function when requesting the supply of power from renewable energy may be stored in the storage 103 in advance, or may be obtained from the EMS 40.

[0098] Next, the power converter 11 that has received the request instruction corresponds to the voltage of the bus 30 measured by the sensor 120, calculates the renewable energy charging amount according to Equation (1) or Equation (2), and records the calculated renewable energy charging amount as a history in the storage 103 (step S312). Step S312 is an example of a management step for managing the renewable energy charging amount. Next, the power converter 11 updates the reference function according to the calculated renewable energy charging amount and the voltage of the bus 30 (step S313), and performs local control using the updated reference function (step S314).

[0099] Here, when Figure 10 the output of the power unit 22 is large and the voltage of the bus 30 is Va3 as shown, since the power P of the line DL11 is negative when the voltage is Va3, the power converter 11 charges the power unit 21. Regarding the power unit 23, the power converter 13 charges it using the power supplied from the power unit 22. In this case, P IO becomes positive, and the renewable energy charging amount increases. In addition, when Figure 11 the output of the power unit 22 is small and the voltage of the bus 30 is Va4 as shown, since the power P of the line DL11 is positive when the voltage is Va4, the power converter 11 outputs the power supplied from the power unit 21 to the bus 30. In this case, P IO becomes negative, and the renewable energy charging amount decreases.

[0100] In addition, the power converter 11 updates the reference function according to the calculated renewable energy charging amount. For example, as the renewable energy charging amount decreases, the power converter 11 decreases the maximum value Pmax of the output of the power P of the reference function. As a result, the reference function of the power converter 11 is updated from the line DL11 to, for example, Figure 13 the line DL12 shown. In addition, when the power converter 11 charges the power unit 21 and the renewable energy charging amount increases, as the renewable energy charging amount increases, the power converter 11 increases the maximum value of the output of the power P of the reference function. The power converter 11 updates to a reference function with Pmax changed so that the output power Pa of the power unit 21 + the output power Pb of the power unit 22 = the power consumption Pc of the power unit 23. When updating the reference function, the power converter 11 may also communicate with the power converters 12 and 13, 15 to obtain the reference functions of the respective power converters.

[0101] In addition, the line DL31 becomes the following reference function: when the supply of power from renewable energy decreases during the charging of the power unit 23 and the voltage of the bus 30 drops, the input power decreases along with the drop in the voltage of the bus 30. In the power converter 13, when the voltage of the bus 30 becomes Va4, since the power supplied from the power units 21 and 22 decreases correspondingly, the power P required for charging the power unit 23 also becomes smaller according to the reference function of the line DL31. Therefore, even if the supply of power from renewable energy decreases, the supply of power from renewable energy can continue. Further, since the line DL31 becomes a reference function that sets the input power to 0 to stop charging when the supply of power from renewable energy decreases and the voltage of the bus 30 drops, it is possible to prevent the situation where power other than the power from renewable energy is used even when power from renewable energy is requested.

[0102] The power converter 11 repeats the processes of step S312 to step S314 until a stop command indicating the stop of the supply of power from renewable energy is sent from the power converter 13. When stopping the charging with the power from renewable energy, the power converter 13 sends the stop command to the power converters 11, 12, and 14 (steps S315 to S317). The power converter 13 that has sent the stop command changes the reference function referred to in its local control to the reference function used when requesting the supply of power from renewable energy (step S318). The power converters 11, 12, and 14 that have received this stop command each change the reference function referred to in their local control to the reference function when the supply of power from renewable energy is not requested (steps S319 to S321). Then, the power converters 11 to 14 each start local control using the changed reference function (steps S322 to S325).

[0103] The power converter 11 manages the amount of power of the power from renewable energy supplied from the power unit 21 as the difference between the amount of renewable energy charging when the request command is received and the amount of renewable energy charging when the stop command is received.

[0104] As described above, according to the present embodiment, since the power unit 21 that is charged with both power from the commercial power grid and power from renewable energy sources calculates the amount of power charged with power from renewable energy sources and the amount of power output from renewable energy sources as the renewable energy charge amount, it is possible to manage the charging and discharging achieved by power from renewable energy sources. In addition, in the present embodiment, since the calculated renewable energy charge amount is recorded together with the date and time as a history record, it is possible to manage the input and output of power from renewable energy sources. Further, according to the present embodiment, when compared with the configuration in which the EMS 40 obtains the input and output power amounts of the power unit 21 from the power converters 11 to calculate the renewable energy charge amount, the renewable energy charge amount is calculated without communication in the power converters 11 that operate autonomously and dispersedly. Therefore, it is possible to reduce the communication cost involved in the management of the renewable energy charge amount. In addition, when the power converter 11 receives a request command, it updates its reference function corresponding to the change in the renewable energy charge amount so as to continue the supply of power from renewable energy sources. Therefore, it is possible to autonomously and dispersedly meet the request for power from renewable energy sources.

[0105] [Modification Example]

[0106] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the present invention can be implemented by modifying the above-described embodiments as follows. In addition, the above-described embodiments and the following modification examples can also be combined in various ways. A solution configured by appropriately combining the constituent elements of the above-described embodiments and each modification example is also included in the present invention. Further, further effects and modification examples 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 modification examples, and various changes can be made.

[0107] In the above-described embodiment, since the power unit 23 is a power storage device capable of supplying and charging power, the power converter 13 can also perform the same operation as the power converter 11 when it receives a request command from another power converter to itself.

[0108] In the above-described embodiment, the request command is sent from the power converter 13 to the power converters 11, 12, and 14, but the request command can also be sent from the power converter 13 only to the power converter 11.

[0109] Figure 14FIG. 0 is a diagram showing a power system 1 with a power converter 16 and a power unit 26 added. The power converter 16 has the same structure as the power converter 11. In addition, the power unit 26 has the same structure as the power unit 21. In this case, the power converter 11 stores the reference function of the power converter 16 in addition to storing the reference function of the power converter 14. In addition, the power converter 16 stores the reference function of the power converter 14 and the reference function of the power converter 11.

[0110] When the power system 1 has the power converter 16 and the power unit 26 in addition to the power converter 11 and the power unit 21, the power converter 11 can manage the renewable energy charging amount by using the reference function of the power converter 11 in addition to using the reference function of the power converter 14. When the power system 1 includes the power converter 16 and the power unit 26 and the output of the power unit 22 is small, through centralized control, as Figure 9 shown, the reference function of the power converter 12 becomes the line DL22. In addition, the reference functions of the power converter 11 and the power converter 16 are the same, which is the line DL2. Since the voltage of the bus 30 measured by the sensor 120 is Figure 9 Va2 as shown, when the voltage is Va2, the power P of the line DL2 is negative. Therefore, the power converter 11 charges the power unit 21. In addition, since the voltage of the bus 30 measured by the sensor 120 is Figure 9 Va2 as shown, when the voltage is Va2, the power P of the line DL2 is negative. Therefore, the power converter 16 also charges the power unit 26.

[0111] Here, the control unit 100 of the power converter 11 determines how to charge the power unit 21 and the power unit 26. If the control unit 100 of the power converter 11 refers to the reference function of the power converter 14, i.e., the line DL41, stored in the memory 103, the power P becomes positive when the voltage of the bus 30 is Va2. That is, when the voltage of the bus 30 is Va2, the power converter 14 outputs to the bus 30, and it is determined that the charging of the power unit 21 and the power unit 26 is performed using the output from the power unit 22 and the output from the power unit 24. In this case, the control unit 100 of the power converter 11 performs the following calculation of formula (4) to calculate the renewable energy charging amount. In addition, the control unit 100 of the power converter 11 records the calculated renewable energy charging amount and the calculated date and time as a history in the memory 103.

[0112] P RE (t + 1) = P RE (t) + P IO(t) × (3 × Va2 - 2 × Vc - Vb) / (Va2 - Vc) ··· (4)

[0113] In addition, when connecting a group of multiple power converters 16 to the power unit 26 and the bus 30, the power converter 11 also stores the reference functions of these power converters, and calculates the renewable energy charging amount based on the stored reference functions.

[0114] In the present invention, when the voltage drop in the bus 30 is large, the power converter 11 can also correct the stored reference function to manage the renewable energy charging amount. Figure 15 It is a diagram showing the reference function of the power converter 11 that corrects from line DL2 to line DL2a considering the voltage drop in the bus 30. For example, when the voltage drop in the bus 30 between the power converter 12 and the power converter 11 is ΔV, the power converter 11 shifts Figure 9 the shown line DL2 downward by ΔV to set it as Figure 15 the shown line DL2a. And when the output of the power unit 22 is small, Vc in the formula (2) is replaced with Vc - ΔV to calculate the renewable energy charging amount.

[0115] Symbol Explanation

[0116] 1 Power system

[0117] 11, 12, 13, 14, 15, 16 Power converters

[0118] 21, 22, 23, 24, 25, 26 Power units

[0119] 30 Bus

[0120] 40 EMS

[0121] 41, 100 Control units

[0122] 42 Storage unit

[0123] 43, 130 Communication units

[0124] 60 External server

[0125] 100a Operation amount setting unit

[0126] 100b Management unit

[0127] 100c Update unit

[0128] 100d Instruction unit

[0129] 101 Processor

[0130] 102 Memory

[0131] 103 Storage

[0132] 104 Input / Output I / F

[0133] 105 Communication I / F

[0134] 106 Bus

[0135] 110 Power Conversion Unit

[0136] 120 Sensor

[0137] DL1, DL2, DL11, DL12, DL21, DL22, DL23, DL31, DL41 Lines

[0138] EV Electric Vehicle

[0139] NW Network.

Claims

1. A power converter, comprising: A power conversion unit connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power from renewable energy are connected, converts the power input from the bus, outputs it to a power unit capable of charging and discharging, converts the power input from the power unit, and outputs it to the bus; A measurement unit that measures the electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; A storage unit that stores a first reference function that defines a target electrical characteristic value corresponding to the electrical characteristic value measured by the measurement unit and a second reference function that defines a target electrical characteristic value of the first power converter corresponding to the electrical characteristic value measured by the first power converter; A setting unit that sets the power conversion characteristics of the power conversion unit based on the electrical characteristic value determined by the first reference function corresponding to the electrical characteristic value measured by the measurement unit; And A management unit that manages the amount of charging to the power unit, i.e., the amount of renewable energy charging, achieved by the renewable energy power supplied from the second power converter to the power conversion unit based on the electrical characteristic value measured by the measurement unit and the second reference function when power is supplied from the bus to the power conversion unit, and manages the amount of renewable energy power supplied from the power unit based on the electrical characteristic value measured by the measurement unit and the amount of renewable energy charging when power is supplied from the power unit charged with renewable energy power to the bus via the power conversion unit.

2. The power converter according to claim 1, wherein The power converter has: An update unit that updates the first reference function corresponding to the amount of renewable energy charging.

3. The power converter according to claim 2, wherein The update unit updates the maximum value of the target value of the output of the power conversion unit specified by the first reference function corresponding to the amount of renewable energy charging.

4. The power converter according to claim 1, wherein The storage unit stores a reference function that defines the target electrical characteristic value of each of a plurality of power converters, wherein the plurality of power converters convert the power input from the bus, output it to a power unit capable of charging and discharging, convert the power input from the power unit, and output it to the bus, The management unit manages the amount of charging to the power unit, i.e., the amount of renewable energy charging, achieved by the renewable energy power supplied from the second power converter to the power conversion unit based on the electrical characteristic value measured by the measurement unit, the second reference function, and the reference function of each of the plurality of power converters.

5. The power converter according to claim 1, wherein The management unit corrects the first reference function based on the voltage drop of the bus.

6. A power system having: A first power converter that converts and outputs power supplied from a power grid; A second power converter that converts and outputs power supplied from a power generation device that generates power using renewable energy; and A DC bus to which the first power converter and the second power converter are connected, The power system includes a power converter having: A power conversion unit that is connected to the bus, converts the power input from the bus, and outputs it to a power unit capable of charging and discharging, and converts the power input from the power unit and outputs it to the bus; A measurement unit that measures the electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; A storage unit that stores a first reference function that defines a target electrical characteristic value corresponding to the electrical characteristic value measured by the measurement unit, and a second reference function that defines a target electrical characteristic value of the first power converter corresponding to the electrical characteristic value measured by the first power converter; A setting unit that sets the power conversion characteristics of the power conversion unit based on the electrical characteristic value determined by the first reference function corresponding to the electrical characteristic value measured by the measurement unit; And A management unit that manages the amount of charge to the power unit achieved by the power from renewable energy supplied from the second power converter to the power conversion unit, that is, the amount of renewable energy charge, based on the electrical characteristic value measured by the measurement unit when supplying power from the bus to the power conversion unit and the second reference function, and manages the amount of power from renewable energy supplied from the power unit based on the electrical characteristic value measured by the measurement unit when supplying power from the power unit charged with power from renewable energy to the bus via the power conversion unit and the amount of renewable energy charge.

7. The power system according to claim 6, wherein The power system has: A third power converter that is connected to the bus, requests power from renewable energy to the power converter, and converts and outputs the power supplied from the power converter to the connected power unit, The third power converter stores a reference function that defines a target electrical characteristic value corresponding to the measured electrical characteristic value and decreases the input power in response to a decrease in the voltage of the bus, and in response to a decrease in the voltage of the bus, decreases the output to the connected power unit based on this reference function.

8. A control method for a power converter, the power converter having a power conversion unit, the power conversion unit being connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power using renewable energy are connected, converts the power input from the bus and outputs it to a power unit capable of charging and discharging, and converts the power input from the power unit and outputs it to the bus, The control method for the power converter includes: Measurement step of measuring electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; Setting step of setting the power conversion characteristics of the power conversion unit based on the electrical characteristic values determined by the first reference function that defines the target electrical characteristic values corresponding to the electrical characteristic values measured in the measurement step; And Management step of managing the amount of charge to the power unit achieved by the power from renewable energy supplied from the second power converter to the power conversion unit, i.e., the renewable energy charge amount, based on the electrical characteristic values measured in the measurement step when supplying power from the bus to the power conversion unit and the second reference function that defines the target electrical characteristic values corresponding to the electrical characteristic values measured by the first power converter, and managing the amount of power from renewable energy supplied from the power unit based on the electrical characteristic values measured in the measurement step when supplying power from the power unit charged with power from renewable energy via the power conversion unit to the bus and the renewable energy charge amount.

9. A program executed by a processor of a power converter, the power converter having a power conversion unit connected to a DC bus to which a first power converter that converts and outputs power supplied from a power grid and a second power converter that converts and outputs power supplied from a power generation device that generates power from renewable energy are connected, the power conversion unit converting the power input from the bus and outputting it to a power unit capable of charging and discharging, and converting the power input from the power unit and outputting it to the bus, The program causes the processor of the power converter to execute: Measurement step of measuring electrical characteristic values of the power input from the bus to the power conversion unit and the power output from the power conversion unit to the bus; Setting step of setting the power conversion characteristics of the power conversion unit based on the electrical characteristic values determined by the first reference function that defines the target electrical characteristic values corresponding to the electrical characteristic values measured in the measurement step; And Management step of managing the amount of charge to the power unit achieved by the power from renewable energy supplied from the second power converter to the power conversion unit, i.e., the renewable energy charge amount, based on the electrical characteristic values measured in the measurement step when supplying power from the bus to the power conversion unit and the second reference function that defines the target electrical characteristic values corresponding to the electrical characteristic values measured by the first power converter, and managing the amount of power from renewable energy supplied from the power unit based on the electrical characteristic values measured in the measurement step when supplying power from the power unit charged with power from renewable energy via the power conversion unit to the bus and the renewable energy charge amount.

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