Power Converter, Power System, Control Method of Power Converter, and Program

Abstract

This power converter comprises: a power conversion unit that is connected to a bus to which a first power converter of a power grid and a second power converter of a device that generates power with renewable energy are connected, and to a rechargeable and dischargeable power element; a measurement unit that measures an electric characteristic value of the bus; a setting unit that sets the characteristics of the power conversion unit using the electric characteristic value and a first reference function in which a target electric characteristic value is defined according to the electric characteristic value; and a management unit that manages a renewable energy recharge amount, which is a recharge amount by the second power converter, using the electric characteristic value of when power is supplied from the bus and a second reference function in which a target electric characteristic value of the first power converter is defined according to the electric characteristic value measured by the first power converter, and manages a power amount derived from renewable energy supplied from the power element on the basis of the electric characteristic value measured when power is supplied to the bus and the renewable energy charge amount.

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 networks that rely on fossil energy or nuclear energy, power networks using locally produced and consumed electricity have attracted attention. In power networks using locally produced and consumed electricity, various devices such as photovoltaic power generation devices (PV), stationary energy storage devices, and electric vehicles (EV) that generate electricity using renewable energy are connected.

[0003] As an invention for managing renewable energy generated in such a power network, 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 provided from a power generation device that generates electricity using renewable energy such as sunlight, hydropower, and wind power, and the amount of power that can be provided. In addition, the charge / discharge system included in this system charges the regenerative power generated by renewable energy and supplies power according to a request. When the power supply and demand management device is requested to supply regenerative power during a time period when power generation using renewable energy is not being performed, it requests the charge / discharge system to supply power. The charge / discharge system supplies power according to the power request.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a power network, power from a commercial power system and power from renewable energy are mixed to charge a storage battery. However, in the system of Patent Document 1, only renewable energy is used to charge the charge-discharge system, and it does not support charging from the commercial power system. Therefore, for a storage battery that can be charged by both power from the commercial power system and power from renewable energy, there is a problem that the input of power from renewable energy cannot be managed. Also, in order to reduce the environmental load, when supplying power from the charged storage battery, power from renewable energy may be required. To meet this requirement, it is necessary to manage how much power from renewable energy is supplied from the storage battery and how much the storage battery is charged as the power is supplied. However, in the system of Patent Document 1, there is a problem that it is impossible to manage how much power from renewable energy is output among the power from the commercial power system and the power from renewable energy.

[0006] The present invention has been made in view of the above, and an object thereof is to manage the input and output of power from renewable energy for a power element that can be charged by both power from a commercial power system and power from renewable energy.

Means for Solving the Problems

[0007] A power converter according to one aspect of the present invention includes 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, which are connected to a DC bus. A power conversion unit is connected to the bus, converts the power input from the bus, and outputs it to a power element capable of charging and discharging, and converts the power input from the power element and outputs it to the bus. A measurement unit 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 stores a first reference function in which a target electrical characteristic value is defined according to the electrical characteristic value measured by the measurement unit, and a second reference function in which a target electrical characteristic value of the first power converter is defined according to the electrical characteristic value measured by the first power converter. A setting unit sets the power conversion characteristics of the power conversion unit based on the electrical characteristic value determined by the first reference function according to the electrical characteristic value measured by the measurement unit. A management unit manages the amount of renewable energy charging to the power element by the power from 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 renewable energy supplied from the power element 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 element charged with power from renewable energy to the bus via the power conversion unit.

[0008] In the power converter according to one aspect of the present invention, an update unit that updates the first reference function according to the amount of renewable energy charging may be provided.

[0009] In the power converter according to one aspect of the present invention, the update unit may update the maximum value of the target value of the output of the power conversion unit defined by the first reference function according to the amount of renewable energy charging.

[0010] Further, in the power converter according to one aspect of the present invention, the storage unit converts the power input from the bus and outputs it to a power element capable of charging and discharging, and converts the power input from the power element and outputs it to the bus. A reference function defining the target electrical characteristic values of the power converter is stored for each of a plurality of power converters. The management unit, based on the electrical characteristic values measured by the measurement unit when power is supplied from the bus to the power conversion unit, the second reference function, and the reference functions for each of the plurality of power converters, manages the amount of renewable energy-derived power supplied from the second power converter to the power conversion unit and used to charge the power element, that is, the amount of renewable energy charging.

[0011] Further, in the power converter according to one aspect of the present invention, the management unit may correct the first reference function based on the voltage drop of the bus.

[0012] A power system according to one aspect of the present invention includes 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 from renewable energy, and a DC bus to which the first power converter and the second power converter are connected. The power system has a power conversion unit that is connected to the bus, converts the power input from the bus, and outputs it to a power element capable of charging and discharging, and converts the power input from the power element and outputs 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 in which a target electrical characteristic value is defined according to the electrical characteristic value measured by the measurement unit, and a second reference function in which a target electrical characteristic value of the first power converter is defined according 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 according to the electrical characteristic value measured by the measurement unit; and a management unit that manages the amount of renewable energy charging, which is the amount of charging of the power element by the power from 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 renewable energy supplied from the power element 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 element charged with power from renewable energy to the bus via the power conversion unit. The power system includes a power converter having the above components.

[0013] A power system according to one aspect of the present invention 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 element. The third power converter may reduce the output to the connected power element in response to a decrease in the voltage of the bus.

[0014] A control method for a power converter according to an aspect of the present invention is a control method for a power converter having a power conversion unit that 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, and that converts the power input from the bus and outputs it to a power element capable of charging and discharging, and converts the power input from the power element and outputs it to the bus. The control method 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 in which a target electrical characteristic value is defined according to the electrical characteristic values measured in the measurement step; a management step of managing the amount of renewable energy charging, which is the amount of charging of the power element by the power derived from renewable energy supplied from the second power converter to the power conversion unit, based on the electrical characteristic values measured in the measurement step and the second reference function in which the target electrical characteristic value of the first power converter is defined according to the electrical characteristic values measured in the measurement step and the electrical characteristic values measured by the first power converter when power is supplied from the bus to the power conversion unit; and a management step of managing the amount of power derived from renewable energy supplied from the power element based on the electrical characteristic values measured in the measurement step and the amount of renewable energy charging when power is supplied from the power element charged with power derived from renewable energy to the bus via the power conversion unit.

[0015] A program according to one aspect of the present invention causes a processor of a power converter having a power conversion unit to execute the following steps. 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 element capable of charge and discharge, and converts the power input from the power element and outputs it to the bus. The program 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 in which a target electrical characteristic value is defined according to the electrical characteristic values measured in the measurement step; a management step of managing the amount of renewable energy charging, which is the amount of charge of the power element by the power from renewable energy supplied from the second power converter to the power conversion unit, based on the electrical characteristic values measured in the measurement step and a second reference function in which the target electrical characteristic value of the first power converter is defined according to the electrical characteristic values measured in the measurement step and the electrical characteristic values measured by the first power converter when power is supplied from the bus to the power conversion unit; and a management step of managing the amount of power from renewable energy supplied from the power element based on the electrical characteristic values measured in the measurement step and the amount of renewable energy charging when power is supplied from the power element charged with power from renewable energy to the bus via the power conversion unit.

Effect of the Invention

[0016] According to the present invention, for a power element that can be charged with both power from a commercial power grid and power from renewable energy, it is possible to manage the input and output of the power from renewable energy.

Brief Description of the Drawings

[0017]

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[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by the embodiments described below. Further, in the description of the drawings, the same parts are appropriately denoted by the same reference numerals.

[0019] [Embodiment] <Configuration of Power System> FIG. 1 is a diagram showing the configuration of a power system according to an embodiment of the present invention. The power system 1 is a system that charges a storage battery with power from a commercial power system and power derived from renewable energy, and can supply power from the charged storage battery. When charging the storage battery, the power system 1 manages charging with power from the commercial power system and charging with power derived from renewable energy, and when supplying power from the storage battery, the power system 1 manages power supply derived from renewable energy and power supply from the commercial power system. The power system 1 includes power converters 11 to 15, power elements 21 to 25, and a bus 30. Further, the power system 1 includes an EMS (Energy Management System) 40. The EMS 40 is an example of a central control device.

[0020] The bus 30 is a DC bus in the power system 1, and the power converters 11 to 15 are connected thereto. In the power system 1, a power network including a DC grid composed of the bus 30, the power converters 11 to 15, and the power elements 21 to 25 is configured.

[0021] The power converters 11 to 13 and 15 are DC / DC converters that convert DC voltage. The power converter 14 is an AC / DC converter that converts between DC voltage and AC voltage. The configuration and functions of the power converters 11 to 15 will be described in detail later.

[0022] The power element 21 is, as an example, 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 an in-facility energy storage device that is permanently installed. The power converter 11 has a function of converting the voltage of the DC power supplied by the power element 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 element 21 to charge the power element 21. The power converter 11 has a function of performing information communication by wire or wirelessly. The power converter 11 communicates with the EMS 40 and controls the input / output to the bus 30 based on a reference function sent from and stored in the EMS 40.

[0023] The power element 22 is, as an example, 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. 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. Note that the power element 22 is not limited to a solar power generation device, and may be a power generation device that generates electric power using renewable energy such as a power generation device that uses hydraulic power or a power generation device that uses wind power.

[0024] The power element 23 is, as an example, an in-vehicle power storage device capable of supplying and charging electric power, and is connected to the power converter 13. The power element 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 a function of converting the voltage of the DC power supplied by the power element 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 element 23 to charge it. The power converter 13 is an example of a third power converter. The power converter 13 is provided, for example, at an electric vehicle charging station or residential charging equipment, 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.

[0025] The power element 24 is, as an example, a commercial power system and is connected to the power converter 14. The power converter 14 converts the AC power supplied by the power element 24 into DC power and outputs it to the bus 30, and also converts the DC power supplied from the bus 30 into AC power and outputs it to the power element 24. The power converter 14 is an example of a first power converter. The output of power from the bus 30 to the power element 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 functions sent from and stored in the EMS 40.

[0026] The power element 25 is a device that consumes power, for example, a device that converts power into kinetic energy or thermal energy. The power converter 15 has a function of converting the voltage of the DC power supplied from the bus 30 and outputting it to the power element 25 to operate the power element 25. The power converter 15 is also an example of a third power converter. The power converter 15 has a function of performing information communication by wire or wirelessly. The power converter 15 communicates with the EMS 40 and controls the output to the power element 25 based on the reference functions sent from and stored in the EMS 40.

[0027] The EMS 40 has a function of integrally 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.

[0028] The control unit 41 performs various arithmetic processes for realizing 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 out and executing various programs from the storage unit 42.

[0029] The storage unit 42 includes, for example, a ROM (Read Only Memory) in which various programs, data, etc. used by the control unit 41 for performing arithmetic processing are stored. Further, the storage unit 42 includes, for example, a RAM (Random Access Memory) that is used to store a work space when the control unit 41 performs arithmetic processing, the results of the arithmetic processing of the control unit 41, etc. The storage unit 42 may include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0030] The communication unit 43 is configured to include a communication module that performs information communication by wire or wirelessly. The communication unit 43 performs information communication 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.

[0031] Note that the external server 60 is a server provided outside the power system 1. The external server 60 is, for example, an information processing device configured to function as an EMS in another power system, or an information processing device provided with a database and functioning as a data server for the EMS 40. The external server 60 stores various information that may affect the operation of the power system 1.

[0032] <Configuration of Power Converter> Next, the specific configuration of the power converter 11 will be described. FIG. 2 is a diagram showing the configuration 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.

[0033] The power conversion unit 110 performs DC / DC conversion to convert the voltage of the DC power input from the discharging power element 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 element 21 to charge the power element 21. The power conversion unit 110 is composed of an electric circuit including, for example, a coil, a capacitor, a diode, a switching element, etc. 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, for example, PWM (Pulse Width Modulation) control.

[0034] The sensor 120 measures the electrical characteristic value 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 value of the power input to or output from the power converter 11. The sensor 120 can measure, as the electrical characteristic value, a current value, a voltage value, a power value, etc. The sensor 120 outputs the measured electrical characteristic value to the control unit 100.

[0035] The communication unit 130 includes a communication module that performs information communication by wire or wirelessly. The communication unit 130 performs information communication with the power converters 12 to 15 and the EMS 40 via the network NW. The communication unit 130 receives, for example, a command transmitted from the EMS 40 or a command transmitted from the power converters 12 to 15 and outputs it to the control unit 100, and transmits the command output from the control unit 100 to the power converters 12 to 15. The command transmitted from the EMS 40 includes reference function information. The reference function information will be described later. Also, the communication unit 130 transmits, for example, information regarding the power situation input from the control unit 100 to the EMS 40. Note that when the information regarding the power situation is the measurement value of the sensor 120, the communication unit 130 may transmit, for example, the electrical characteristic value input from the sensor 120 to the EMS 40.

[0036] FIG. 3 is a block diagram showing the configuration of the control unit 100. The control unit 100 is configured such that a processor 101, a memory 102, a storage 103, an input / output I / F 104, and a communication I / F 105 are connected to a bus 106. The memory 102 is, for example, a RAM and is composed of a volatile memory or a non-volatile memory. The memory 102 serves as a work space when the processor 101 performs arithmetic processing and stores the results of the arithmetic processing of the processor. The storage 103 is composed of a ROM and an auxiliary storage device such as an HDD or an SSD. The storage 103 stores programs and data used by the processor 101 to perform arithmetic processing. Further, 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 outputs a signal for controlling the power conversion unit 110 under the control of the processor 101. Also, the input / output I / F 104 is connected to the sensor 120 and acquires the electrical characteristic values output from the sensor 120 and outputs them 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 a program from the storage 103, and executes it using the memory 102 as a work space. The processor 101 may be an ASIC, an FPGA, a DSP, or a GPU. By executing the program by the processor 101, the functions of the power converter 11 are realized.

[0037] FIG. 4 is a diagram showing the functional units according to the present invention realized in the control unit 100. The control unit 100 includes an operation amount setting unit 100a, a management unit 100b, an update unit 100c, and a command unit 100d, which are functional units realized software-wise by executing a program.

[0038] The operation amount setting unit 100a sets a target value for 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, for example, a voltage value or a power value. Also, the operation amount setting unit 100a performs feedback control to set an operation amount (for example, a duty ratio) for PWM control so that the difference between the electrical characteristic value measured by the sensor 120 and the set target value is within a predetermined range. The feedback control performed by the operation amount setting unit 100a can be executed using a known method such as PID control in which parameters such as a proportional gain, an integral time, and a differential time stored in the storage 103 in advance are read out and executed. The operation amount setting unit 100a outputs information on the set operation amount to the power conversion unit 110 and controls the power conversion unit 110.

[0039] The management unit 100b manages the amount of charge (renewable energy charge amount) by the power derived from renewable energy for the power elements connected to the power conversion unit 110. The update unit 100c updates the reference function used for the control of the power conversion unit 110 according to the renewable energy charge amount. The command unit 100d transmits a command for making a request to another power converter to the other power converter via the communication unit 130.

[0040] Note that the other power converters 12, 13, 14, 15 may have the same configuration as the power converter 11. However, the power conversion unit 110 of the power converter 14 performs AC / DC conversion that converts the AC power supplied from the power element 24 into DC power and outputs it to the bus 30, and DC / AC conversion that converts the DC power supplied from the bus 30 into AC power and outputs it to the power element 24.

[0041] <Characteristics of the reference function> Next, the reference function that serves as the basis for the control unit 100 to control the power conversion characteristics of the power conversion unit 110 will be described. FIG. 5 is a diagram showing an example of the reference function indicated by the reference function information. The reference function information is various information for specifying the droop functions that make up the reference function. In FIG. 5, the vertical axis is voltage V and the horizontal axis is power P. The reference function shown in FIG. 5 indicates the V-P characteristic, which is the relationship between the power P and the voltage V on the bus 30 side of the power conversion unit 110 included in the power converter 11, and shows the power conversion characteristics of the power conversion unit 110. Note that the power P is a positive value when the power conversion unit 110 supplies power to the bus 30, that is, when the power element 21 is in a discharging state, and is a negative value when power is supplied from the bus 30, that is, when the power element 21 is in a charging state. Also, the state where the power P = 0 is a state where neither charging nor discharging is occurring.

[0042] The reference function represented by the line DL1 that bends midway in FIG. 5 is configured by connecting a plurality of droop functions that are defined according to the input value interval and have different drooping characteristics from each other. Specifically, the line DL1 is configured by connecting five droop functions with different drooping characteristics from each other and is specified by the reference function information. The reference function information includes, for example, the coordinate information of the boundaries of the droop functions, 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.) in the coordinates with the horizontal axis being P and the vertical axis being V.

[0043] The control unit 100 of the power converter 11 controls the power conversion characteristics of the power converter 11 to be the characteristics of the reference function indicated 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 value of the voltage V and the value of the power P, which are the electrical characteristic values on the bus 30 side of the power conversion unit 110, is located on the line DL1.

[0044] Note that as control methods executed by the control unit 100, there are droop P control and droop V control. Droop P control is a control method that determines a target power value, which is a target value, based on a voltage value, which is an electrical characteristic value measured by the sensor 120, and a reference function, and makes the difference between the measured power value by the sensor 120 and the target power value fall within an allowable range. Droop V control is a control method that determines a target voltage value, which is a target value, based on a power value, which is an electrical characteristic value measured by the sensor 120, and a reference function, and makes the difference between the measured voltage value by the sensor 120 and the target voltage value fall within an allowable range.

[0045] <Control method> 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 perform control individually and autonomously and distributedly, and centralized control in which the EMS 40 performs cooperative control of the power converters 11 to 15 according to the power situation of the power system 1 can be executed. Note that, 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.

[0046] <Centralized control> 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 by a command. Updating the reference function information by a command means that the command includes reference function information regarding the reference function and updates part or all of the reference function by the command. Each storage 103 of the power converters 11 to 15 stores the reference function information in an updatable manner.

[0047] 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 command for updating the reference function. The reference function information used for this update is stored in the storage unit 42 of the EMS 40, and the control unit 41 reads and uses it as appropriate.

[0048] Next, an example of the control method of the power system 1 by centralized control will be described with reference to the sequence diagram of FIG. 6. First, the EMS 40 calls the timer of its own device and starts timing (step S101). Next, the EMS 40 requests the self-terminal measurement information from each of the power converters 11 to 15 (step S102). The self-terminal measurement information is an example of information regarding the power situation of the power system 1 and includes the electrical characteristic values measured by the respective sensors 120 of the power converters 11 to 15 and the measurement times of the electrical characteristic values.

[0049] Next, the power converters 11 to 15 transmit the self-terminal measurement information they have acquired to the EMS 40 (step S103). The EMS 40 stores the respective self-terminal measurement information in the storage unit 42. Next, the EMS 40 requests various types of information that may affect the operation of the power system 1 from the external server 60 as an example of information regarding the power situation of the power system 1 (step S104). In this example, the EMS 40 requests the power generation amount and demand prediction information from the external server 60. The power generation amount and demand prediction information includes the prediction information of the power generation amount and the power demand prediction information in the power system 1, and may include information such as the season and current weather of the area where the power system 1 is installed and the future weather forecast. Also, when the external server 60 functions as the EMS of another power system, if the operation state of the other power system may affect the operation of the power system 1, the power generation amount and demand prediction information may include the prediction information of the power generation amount and the power demand prediction information in the other power system. Next, the external server 60 transmits the power generation amount and demand prediction information to the EMS 40 (step S105). The EMS 40 stores the power generation amount and demand prediction information in the storage unit 42.

[0050] Next, the control unit 41 of the EMS 40 reads out each piece of transmitted information, that is, information regarding the power status of the power system 1, etc. from the storage unit 42, and based on this, executes an operation optimization calculation for the power system 1 (step S106). The operation optimization calculation is executed to apply to various conditions. For example, assume that the power system 1 is controlled so that the bus 30 becomes an operating point with a predetermined voltage. In this state, if the EMS 40 predicts from the power generation amount and demand prediction information that the future weather in the area where the power element 22, which is a solar power generation device, is installed will be sunny and the power generation amount will increase, and determines from the self-terminal measurement information obtained from the power converter 12 connected to the power element 22 that there is a margin in power supply to the power element 22. In this case, the EMS 40 determines to update the reference function of the power converter 11 connected to the power element 21 so that the power element 21, which is a stationary energy storage device, is charged at the said operating point. Also, simultaneously with the said update, the EMS 40 determines to update the reference function of the power converter 14 connected to the power element 24 so that no power is supplied from the power element 24, which is a commercial power system. Also, the operation optimization calculation is conditionally set and can also be executed from viewpoints such as not exceeding the contract power of the power element 24, which is a commercial power system, such as peak cut and utilization of nighttime power, and optimization of electricity charges.

[0051] Next, based on the result of the operation optimization calculation, the EMS 40 sets reference function information suitable for the power converter to be updated among the power converters 11 to 15, and outputs an update command 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 command of the reference function and updates the reference function information (step S109). The power converter that has finished updating the reference function information executes self-terminal control (step S110).

[0052] <Self-terminal control> Next, regarding the control method of the power converters 11 to 15 in self-terminal control, the power converter 11 will be described as an example. Note that the same control method as the following description may be appropriately executed for the other power converters 12 to 15.

[0053] In the control method of the power converter 11, the control unit 100 executes a control step of controlling 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 described more specifically with reference to the drawings.

[0054] FIG. 7 is a flowchart showing the flow of processing performed by the control unit 100. The control unit 100 executes the processing shown in FIG. 7, for example, 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).

[0055] Next, the control unit 100 sets a target value for 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 that intersects when a line is drawn along the horizontal axis from the position of the operating point specified from the electrical characteristic values measured by the sensor 120 is set as the target value. For example, when the reference function is as shown in FIG. 5 and the operating point is at the position of OP1 shown in FIG. 5 on the V-P characteristic, the control unit 100 sets P1, which is the power value of the reference function that intersects when a line is drawn along the horizontal axis from the operating point, as the target value. Also, when the control unit 100 performs droop V control, the voltage value of the reference function that intersects when a line is drawn along the vertical axis from the power value measured by the sensor 120 is set as the target value. For example, when the reference function is as shown in FIG. 5 and the operating point is at the position of OP1 shown in FIG. 5 on the V-P characteristic, the control unit 100 sets V1, which is the voltage value of the reference function that intersects when a line is drawn along the vertical axis from the operating point, as the target value.

[0056] 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 is within a predetermined 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.

[0057] <Management of Renewable Energy> In the present embodiment, the power converter 11 monitors the amount of power when charging the power element 21 with power derived from renewable energy and the amount of power when supplying the charged power derived from renewable energy from the power element 21 to the bus 30, and manages the amount of charge (renewable energy charge amount) of the power element 21 with power derived from renewable energy. Hereinafter, a method for managing the renewable energy charge amount will be described. In the present embodiment, the charge amount of the power element 21 at time t is P(t) [Wh], and the renewable energy charge amount is P RE (t) [Wh]. Also, in the present embodiment, the amount of power input and output of the power element 21 from time t-1 to time t measured by the sensor 120 is P IO (t) [Wh]. Note that P IO (t) is positive when charging the power element 21 and negative when discharging the power element 21.

[0058] First, a method for managing P RE (t) when charging the power element 21 will be described. Specifically, the control unit 100 of the power converter 11 has acquired a reference function of the power converter 14 from the EMS 40 in advance and stored it in the storage 103. The control unit 100 of the power converter 11 uses the reference function of the power converter 14 stored in the storage 103 in advance to manage P RE (t).

[0059] For example, when the output of the power element 22 is large, through centralized control, as shown in FIG. 8, the reference function of the power converter 11 is the line DL2, the reference function of the power converter 12 is the line DL21, and the reference function of the power converter 14 is the line DL41. When the voltage of the bus 30 measured by the sensor 120 is Va1 shown in FIG. 8, the power converter 11 charges the power element 21 because the power P of the line DL2 is negative when the voltage is Va1. Here, the control unit 100 of the power converter 11 determines how the charging of the power element 21 is performed. By referring to the line DL41, which is the reference function of the power converter 14 stored in the storage 103, the control unit 100 of the power converter 11 finds that the power P is a negative value 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, there is a reverse power flow and no output to the bus 30, and it is determined that the charging of the power element 21 is performed only by the output from the power element 22. In this case, the control unit 100 of the power converter 11 calculates the amount of renewable energy charging by performing the calculation of the following formula (1). Also, the control unit 100 of the power converter 11 records the calculated amount of renewable energy charging in the storage 103 as a history together with the calculated date and time. P RE (t + 1)=P RE (t)+P IO (t)···(1)

[0060] Next, when the output of the power element 22 is small, by centralized control, as shown in FIG. 9, the reference function of the power converter 12 becomes the line DL22. When the voltage of the bus 30 measured by the sensor 120 in the power converter 11 is Va2 shown in FIG. 9, since the power P of the line DL2 is negative when the voltage is Va2, the power element 21 is charged. Here, the control unit 100 of the power converter 11 determines how the charging of the power element 21 is performed. Referring to the line DL41, which is the reference function of the power converter 14 stored in the storage 103, the control unit 100 of the power converter 11 finds that the power P is a positive value when the voltage of the bus 30 is Va2. That is, when the voltage of the bus 30 is Va2, it is determined that the power converter 14 is outputting to the bus 30 and the charging of the power element 21 is performed by the output from the power element 22 and the output from the power element 24. In this case, the control unit 100 of the power converter 11 calculates the amount of regenerative energy charging by performing the calculation of the following equation (2). Further, the control unit 100 of the power converter 11 records the calculated amount of regenerative energy charging in the storage 103 as a history together with the calculated date and time. P RE (t + 1)=P RE (t)+P IO (t)×(2×Va2 - Vc - Vb) / (Va2 - Vc)···(2)

[0061] Next, P when the power converter 13 makes a request for power derived from renewable energy REA method for managing (t) will be described. For example, when the output of power element 22 is large, as shown in FIG. 10, the reference function of power converter 11 is line DL11, the reference function of power converter 12 is line DL21, and the reference function of power converter 13 is line DL31. When the voltage of bus 30 measured by sensor 120 is Va3 shown in FIG. 10, the control unit 100 of power converter 11 supplies power to power element 21 to charge power element 21 because the power P on line DL11 is negative when the voltage is Va3. In this case, the control unit 100 of power converter 11 performs the calculation of the formula (1) above. Also, the control unit 100 of power converter 11 records the calculated regenerative energy charge amount as a history in storage 103 together with the calculated date and time. Note that for power converter 13 that requests power derived from renewable energy, the required power is covered by the power supply from power element 21.

[0062] Next, for example, when the output of power element 22 is small, as shown in FIG. 11, the reference function of power converter 11 is line DL11, the reference function of power converter 12 is line DL23, and the reference function of power converter 13 is line DL31. When the voltage of bus 30 measured by sensor 120 is Va4 shown in FIG. 11, the control unit 100 of power converter 11 supplies the power from power element 21 to bus 30 because the power P on line DL11 is positive when the voltage is Va4. Also, the control unit 100 of power converter 11 calculates the regenerative energy charge amount according to the formula (1). Here, since power element 21 is supplying power and P IO (t) in the formula (1) is a negative value, the regenerative energy charge amount decreases as the power supply continues. The control unit 100 of power converter 11 records the calculated regenerative energy charge amount as a history in storage 103 together with the calculated date and time. Note that when the control unit 100 of power converter 11 is requested for power derived from renewable energy from power converters 13 and 15 and P RE (t) = 0, the calculation of the formula (3) is performed to calculate the charge amount of power element 21. P(t + 1)=P(t)+P IO (t)···(3)

[0063] Further, when the control unit 100 of the power converter 11 is not requested for power from the power converters 13 and 15 and P(t) is not 0, the control unit 100 of the power converter 11 calculates the formula (3). When the control unit 100 of the power converter 11 is not requested for power from the power converters 13 and 15 and P(t) = 0, the control unit 100 calculates the formula (1) and records the calculated amount of renewable energy charging as a history together with the calculated date and time in the storage 103.

[0064] In addition, in FIGS. 10 and 11, the illustration of the reference function of the power converter 15 is omitted. However, since the power element 25 is a device that consumes power, the reference function of the power converter 15 is the same as the reference function of the line DL31.

[0065] <Power supply from renewable energy> Next, an operation example when supplying power from the power element 21 charged with power from renewable energy will be described. FIG. 12 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 element 23 with power from renewable energy, the power converter 13 transmits a request command for requesting power from renewable energy to the power converters 11, 12, and 14 (steps S301 to S303). Note that the power converter that transmits the request command is not limited to the power converter 13, and the power converter 15 may transmit it, or both the power converter 13 and the power converter 15 may transmit it. Further, the request command may be transmitted by the EMS 40 instead of the power converter 13.

[0066] The power converter 13 that has sent the request command changes the reference function it refers to in self-terminal 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 this request command changes the reference function it refers to in self-terminal control to the reference function used when being requested the supply of power from renewable energy (steps S305 to S307). Subsequently, each of the power converters 11 to 14 starts self-terminal control using the changed reference function (steps S308 to S311). Note that the reference function when being requested the supply of power from renewable energy may be stored in the storage 103 in advance, or may be acquired from the EMS40.

[0067] Next, the power converter 11 that has received the request command calculates the amount of regenerative charge using Equation (1) or Equation (2) according to the voltage of the bus 30 measured by the sensor 120, and records the calculated amount of regenerative charge in the storage 103 as a history (step S312). Step S312 is an example of a management step for managing the amount of regenerative charge. Subsequently, the power converter 11 updates the reference function according to the calculated amount of regenerative charge and the voltage of the bus 30 (step S313), and performs self-terminal control using the updated reference function (step S314).

[0068] Here, as shown in FIG. 10, when the output of the power element 22 is large and the voltage of the bus 30 is Va3, since the power P of the line DL11 is negative when the voltage is Va3, the power converter 11 charges the power element 21. For the power element 23, charging is performed by the power converter 13 with the power supplied from the power element 22. In this case, P IO (t) becomes a positive value, and the amount of regenerative charge increases. Also, as shown in FIG. 11, when the output of the power element 22 is small and the voltage of the bus 30 is Va4, since the power P of the line DL11 is positive when the voltage is Va4, the power converter 11 outputs the power supplied by the power element 21 to the bus 30. In this case, P IO (t) becomes a negative value, and the amount of regenerative charge decreases.

[0069] Note that the power converter 11 updates the reference function according to the calculated regenerative energy charge amount. For example, as the regenerative energy charge amount decreases, the power converter 11 decreases Pmax, which is the maximum value 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, for example, line DL11 to line DL12 shown in FIG. 13. Further, when the power element 21 is charged and the regenerative energy charge amount increases, the power converter 11 increases the maximum value of the output of the power P of the reference function as the regenerative energy charge amount increases. The power converter 11 updates the reference function to a reference function with Pmax changed so that, for example, the output power Pa of the power element 21 + the output power Pb of the power element 22 = the power consumption Pc of the power element 23. When updating the reference function, the power converter 11 may communicate with the power converter 12 and the power converters 13 and 15 to obtain the reference functions of the respective power converters.

[0070] Note that line DL31 is a reference function that reduces the input power as the voltage of bus 30 drops when the supply of power from renewable energy decreases during charging of power element 23. In power converter 13, when the voltage of bus 30 becomes Va4, the power P required for charging power element 23 also decreases according to the reference function of line DL31 in response to the decrease in the power supplied from power element 21 and power element 22. Therefore, even if the supply of power from renewable energy decreases, the supply of power from renewable energy can be continued. Further, since line DL31 is a reference function that stops charging by setting the input power to 0 when the supply of power from renewable energy decreases and the voltage of bus 30 drops, it is possible to prevent the use of power other than the power from renewable energy even though power from renewable energy is required.

[0071] The power converter 11 repeats the processes of step S312 to step S314 until a stop command instructing the stop of the power supply from the renewable energy is transmitted from the power converter 13. When the power converter 13 stops charging with the power from the renewable energy, it transmits a stop command to the power converters 11, 12, and 14 (steps S315 to S317). The power converter 13 that has transmitted the stop command changes the reference function it refers to in the local control to the reference function used when not requesting the supply of the power from the renewable energy (step S318). Each of the power converters 11, 12, and 14 that has received this stop command changes the reference function it refers to in the local control to the reference function when not being requested to supply the power from the renewable energy (steps S319 to S321). Subsequently, each of the power converters 11 to 14 starts the local control using the changed reference function (steps S322 to S325).

[0072] The power converter 11 manages the difference between the amount of renewable energy charging when a request command is received and the amount of renewable energy charging when a stop designation is received as the amount of power of the power from the renewable energy supplied from the power element 21.

[0073] As described above, according to the present embodiment, for the power element 21 that is charged by both the power from the commercial power system and the power from renewable energy, the amount of power when charged with the power from renewable energy and the amount of power when the power from renewable energy is output are calculated as the renewable energy charge amount, so that the charging and discharging of the power from renewable energy can be managed. Further, in the present embodiment, since the calculated renewable energy charge amount is recorded as a history together with the date and time, the input and output of the power from renewable energy can be managed. Further, according to the present embodiment, compared with the configuration in which the EMS 40 acquires the amount of power input and output of the power element 21 from the power converter 11 and calculates the renewable energy charge amount, the calculation of the renewable energy charge amount is performed without communication in the power converter 11 that operates in an autonomous and decentralized manner, so that the communication cost related to the management of the renewable energy charge amount can be reduced. Further, when the power converter 11 receives a request command, it updates its own reference function according to the change in the renewable energy charge amount so that the supply of the power from renewable energy can be continued, so that the request for the power from renewable energy can be satisfied in an autonomous and decentralized manner.

[0074] [Modification Example] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the present invention may be implemented by modifying the above-described embodiments as follows. Note that the above-described embodiments and the following modification examples may be combined with each other. The present invention also includes those configured by appropriately combining the components of the above-described embodiments and each modification example. Further, additional 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 are possible.

[0075] In the above-described embodiment, since the power element 23 is a power storage device capable of supplying power and charging, the power converter 13 may perform the same operation as the power converter 11 when it receives a request command from another power converter.

[0076] In the above-described embodiment, the request command is transmitted from the power converter 13 to the power converters 11, 12, and 14. However, the request command may be sent from the power converter 13 to only the power converter 11.

[0077] FIG. 14 is a diagram showing the power system 1 to which the power converter 16 and the power element 26 are added. The power converter 16 has the same configuration as the power converter 11. Also, the power element 26 has the same configuration as the power element 21. In this case, the power converter 11 stores the reference function of the power converter 16 in addition to the reference function of the power converter 14. Also, the power converter 16 stores the reference function of the power converter 14 and the reference function of the power converter 11.

[0078] When the power system 1 has the power converter 16 and the power element 26 in addition to the power converter 11 and the power element 21, the power converter 11 may manage the amount of renewable energy charging using the reference function of the power converter 11 in addition to the reference function of the power converter 14. When the power system 1 includes the power converter 16 and the power element 26 and the output of the power element 22 is small, by centralized control, as shown in FIG. 9, the reference function of the power converter 12 becomes the line DL22. Note that the reference function of the power converter 11 and the reference function of the power converter 16 are the same on the line DL2. When the voltage of the bus 30 measured by the sensor 120 is Va2 shown in FIG. 9, since the power P on the line DL2 is negative when the voltage is Va2, the power converter 11 charges the power element 21. Also, when the voltage of the bus 30 measured by the sensor 120 is Va2 shown in FIG. 9, the power converter 16 also charges the power element 26 since the power P on the line DL2 is negative when the voltage is Va2.

[0079] Here, the control unit 100 of the power converter 11 determines how the power elements 21 and 26 are charged. When the control unit 100 of the power converter 11 refers to the line DL41, which is the reference function of the power converter 14 stored in the storage 103, the power P is a positive value when the voltage of the bus 30 is Va2. That is, when the voltage of the bus 30 is Va2, it is determined that the power converter 14 is outputting to the bus 30, and the charging of the power elements 21 and 26 is performed by the output from the power element 22 and the output from the power element 24. In this case, the control unit 100 of the power converter 11 performs the calculation of the following formula (4) to calculate the regenerative charge amount. Further, the control unit 100 of the power converter 11 records the calculated regenerative charge amount as a history in the storage 103 together with the date and time of the calculation. P RE (t + 1)=P RE (t)+P IO (t)×(3×Va2 - 2×Vc - Vb) / (Va2 - Vc)···(4) In addition, when a plurality of sets of the power converter 16 and the power element 26 are connected to the bus 30, the power converter 11 also stores the reference functions of these power converters and calculates the regenerative charge amount based on the stored reference functions.

[0080] In the present invention, when the voltage drop in the bus 30 is large, the power converter 11 may correct the stored reference function to manage the regenerative charge amount. FIG. 15 is a diagram showing the reference function of the power converter 11 corrected from the line DL2 to the line DL2a in consideration of 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 the line DL2 shown in FIG. 9 downward by ΔV to obtain the line DL2a shown in FIG. 15. And when the output of the power element 22 is small, the Vc in the above-mentioned formula (2) is replaced with Vc - ΔV to calculate the regenerative charge amount.

Explanation of Signs

[0081] 1 Power system 11, 12, 13, 14, 15, 16 Power converters 21, 22, 23, 24, 25, 26 Power elements 30 Bus 40 EMS 41, 100 Control unit 42 Memory unit 43, 130 Communication unit 60 External server 100a Operation amount setting unit 100b Management unit 100c Update unit 100d Command unit 101 Processor 102 Memory 103 Storage 104 Input / output I / F 105 Communication I / F 106 Bus 110 Power conversion unit 120 Sensor DL1, DL2, DL11, DL12, DL21, DL22, DL23, DL31, DL41 Lines EV Electric vehicle NW Network

Claims

1. A first power converter that converts and outputs the power supplied from a power system, and a second power converter that converts and outputs the power supplied from a power generation device that generates power from renewable energy are connected to a DC bus. A power conversion unit is connected to the bus, converts the power input from the bus, and outputs it to a power element capable of charging and discharging, and converts the power input from the power element 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 in which a target electrical characteristic value is defined according to the electrical characteristic value measured by the measurement unit, and a second reference function in which the target electrical characteristic value of the first power converter is defined according 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 according to the electrical characteristic value measured by the measurement 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, the amount of renewable energy-derived power supplied from the second power converter to the power conversion unit to charge the power element, that is, the amount of renewable energy charge, is managed. When power is supplied from the power element charged with renewable energy-derived power to the bus via the power conversion unit, based on the electrical characteristic value measured by the measurement unit and the amount of renewable energy charge, the amount of renewable energy-derived power supplied from the power element is managed. A power converter comprising the above.

2. Having an update unit that updates the first reference function according to the amount of renewable energy charge. The power converter according to Claim 1.

3. The update unit updates the maximum value of the target value of the output of the power conversion unit defined by the first reference function according to the amount of renewable energy charge. The power converter according to Claim 2.

4. The storage unit stores a reference function in which the target electrical characteristic value of each of a plurality of power converters that convert the power input from the bus and output it to a power element capable of charging and discharging, and convert the power input from the power element and output it to the bus is defined. When power is supplied from the bus to the power conversion unit, the management unit manages the amount of renewable energy-derived power charging to the power element, which is the amount of charging by the 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 for each of the plurality of power converters. The power converter according to claim 1.

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

6. 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 from renewable energy. A DC bus to which the first power converter and the second power converter are connected. A power system having: A power conversion unit connected to the bus, converting the power input from the bus and outputting it to a power element capable of charge and discharge, and converting the power input from the power element and outputting 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 in which a target electrical characteristic value is defined according to the electrical characteristic value measured by the measurement unit, and a second reference function in which the target electrical characteristic value of the first power converter is defined according 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 according to the electrical characteristic value measured by the measurement unit. When power is supplied from the bus to the power conversion unit, the management unit manages the amount of renewable energy-derived power charging to the power element, which is the amount of charging by the 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, and manages the amount of power from renewable energy supplied from the power element based on the electrical characteristic value measured by the measurement unit and the amount of renewable energy-derived power charging when power is supplied from the power element charged with renewable energy-derived power to the bus via the power conversion unit. A power converter having A power system comprising.

7. A third power converter connected to the bus, requesting power derived from renewable energy to the power converter, and converting and outputting the power supplied from the power converter to the connected power element. The third power converter stores a reference function that defines a target electrical characteristic value according to the measured electrical characteristic value and reduces the input power according to a decrease in the voltage of the bus, and reduces the output to the connected power element based on the reference function according to a decrease in the voltage of the bus. The power system according to claim 6.

8. A control method for a power converter having a power conversion unit that is connected to a DC bus to which a first power converter that converts and outputs power supplied from a power system 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 element capable of charge and discharge, and converts the power input from the power element and outputs it to the bus, the method comprising: 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 in which a target electrical characteristic value is defined according to the electrical characteristic values measured in the measurement step; Based on the second reference function in which the target electrical characteristic value of the first power converter is defined according to the electrical characteristic values measured in the measurement step and the electrical characteristic values measured by the first power converter when power is supplied from the bus to the power conversion unit, manage the amount of renewable energy charging to the power element by the power derived from renewable energy supplied from the second power converter to the power conversion unit, and when power is supplied from the power element charged with power derived from renewable energy to the bus via the power conversion unit, manage the amount of power derived from renewable energy supplied from the power element based on the electrical characteristic values measured in the measurement step and the amount of renewable energy charging. A control method for a power converter comprising the above steps.

9. A program that causes a processor of a power converter having a power conversion unit to execute, 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 system 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 converting the power input from the bus and outputting it to a power element capable of charging and discharging, and converting the power input from the power element and outputting it to the bus. 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 in which a target electrical characteristic value is defined according to the electrical characteristic values measured in the measurement step. Based on the electrical characteristic values measured in the measurement step when power is supplied from the bus to the power conversion unit and the electrical characteristic values measured by the first power converter, and a second reference function in which a target electrical characteristic value of the first power converter is defined, manage the amount of renewable energy charging, which is the amount of charging of the power element by the power derived from renewable energy supplied from the second power converter to the power conversion unit. When power is supplied from the power element charged with power derived from renewable energy to the bus via the power conversion unit, manage the amount of power derived from renewable energy supplied from the power element based on the electrical characteristic values measured in the measurement step and the amount of renewable energy charging. A program for causing the above to be executed.

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