Power conversion system

Abstract

To provide a power conversion system to which a power storage unit is connected capable of precisely measuring the amount of electricity output by each source from a power conversion system.SOLUTION: An AC power meter (14) is placed between an inverter (12) and a distribution board (3). A first DC power meter (151) is placed between the inverter (12) and a junction (N1) of a first DC / DC converter (11a) and a second DC / DC converter (11b). A second DC power meter (152) is placed between the junction (N1) and the first DC / DC converter (11a). A third DC power meter (153) is placed between the first DC / DC converter (11a) and a power generation unit (6). A fourth DC power meter (154) is placed between the junction (N1) and the second DC / DC converter (11b). A fifth DC power meter (155) is placed between the second DC / DC converter (11b) and a stationary-type power storage unit (7).SELECTED DRAWING: Figure 8

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power conversion system to which a power storage unit is connected. BACKGROUND ART

[0002] As of 2023, housing prices in Japan have risen due to the impact of soaring construction material prices and the depreciation of the yen. Along with this, when installing a photovoltaic power generation system for realizing a ZEH (Zero Energy House), an increasing number of cases use the PPA (Power Purchase Agreement) service which requires no initial investment. The PPA service adopts a form in which a PPA operator owns the photovoltaic power generation system installed in a residence or the like, and is a mechanism that charges a contractor for the self-consumed amount of photovoltaic power generation. Maintenance of the photovoltaic power generation system is also performed by the PPA operator. In recent years, an increasing number of major electric power companies provide PPA services for the purpose of customer retention.

[0003] Conventionally, PPA operators have installed a smart meter between a power conditioner and a distribution board to measure the amount of electric power for self-consumption billing. This smart meter needs to be replaced every 10 years, which has been a burden on PPA operators. In April 2022, the Act on Strengthening Resilience of Energy Supply was enacted, and electric power trading using power measurement results of power conditioners, which reduces the burden on PPA operators, was permitted.

[0004] As of 2023, grid power prices remain high in Japan due to the impact of soaring resource prices and the depreciation of the yen, and the grid power price per kWh continues to exceed the feed-in tariff of photovoltaic power per kWh. The purchase price of photovoltaic power under the feed-in tariff (FIT) system has been decreasing year by year, and it is predicted that the state where the feed-in tariff of photovoltaic power is lower than the grid power price will continue in the future.

[0005] Therefore, there is a growing need to store solar power in batteries for self-consumption. Accordingly, systems that link solar power generation systems and energy storage systems (hereinafter referred to as hybrid energy storage systems) are becoming widespread (see, for example, Patent Document 1). PPA operators are also strengthening the deployment of hybrid energy storage systems in order to improve the economic value they provide to their customers. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-118209 [Overview of the project] [Problems that the invention aims to solve]

[0007] In multi-input power conditioners, which have stationary batteries and vehicle-mounted batteries connected to the input side in addition to solar panels, it has been difficult to charge based on usage even when measuring the output power of the multi-input power conditioner with a smart meter, because the origin of the electricity charged in the stationary batteries and vehicle-mounted batteries is unknown. As of 2023, PPA (Power Purchase Agreement) projects basically use a monthly flat-rate billing system. Many PPA operators want to switch from monthly flat-rate billing to usage-based billing. Therefore, there is a need to accurately measure the renewable energy-derived electricity that is actually consumed on-site.

[0008] This disclosure is made in view of these circumstances, and its purpose is to provide a technology for accurately measuring the amount of electricity output from a power conversion system by source in a power conversion system to which an energy storage unit is connected. [Means for solving the problem]

[0009] To solve the above problems, a power conversion system in one aspect of the present disclosure includes: a first DC / DC converter connected to a power generation device that converts renewable energy into electrical energy; a second DC / DC converter connected to a stationary energy storage unit; an inverter whose DC terminal side is connected to the junction of the first DC / DC converter and the second DC / DC converter, and whose AC terminal side is connected to a distribution board connected to the grid and load; an AC power meter installed between the inverter and the distribution board; and a first DC power meter installed between the inverter and the junction. The system includes a meter, a second DC power meter installed between the confluence point and the first DC / DC converter, a third DC power meter installed between the first DC / DC converter and the power generator, a fourth DC power meter installed between the confluence point and the second DC / DC converter, a fifth DC power meter installed between the second DC / DC converter and the stationary energy storage unit, and a control unit that measures the amount of power originating from the power generator output to the distribution board based on the power measured by the AC power meter and the first DC power meter to the fifth DC power meter, respectively.

[0010] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between devices, systems, methods, computer programs, etc., are also valid forms of this disclosure. [Effects of the Invention]

[0011] According to this disclosure, in a power conversion system to which an energy storage unit is connected, the amount of energy output from the power conversion system by source can be measured with high precision. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows the basic configuration of a tri-hybrid energy storage system. [Figure 2] This diagram shows a table of tolerance classes according to transaction size, as indicated in the guidelines for the specific measurement system. [Figure 3]This is an explanatory diagram regarding the handling of apportionment measurement under the specific measurement system, as published on the website of the Agency for Natural Resources and Energy. [Figure 4] This diagram shows the configuration of a tri-hybrid energy storage system equipped with a function to measure the amount of electricity from each source. [Figure 5] Figure 4 shows the power at each measurement point of the power conversion system and the amount of electricity stored in the stationary battery, categorized by origin. [Figure 6] Figure 5 shows the power at each measurement point of the power conversion system, organized into input power to the DC bus and output power from the DC bus. [Figure 7] This figure shows a graph summarizing the calculation algorithm for power values ​​by source. [Figure 8] This diagram shows the configuration of a hybrid energy storage system equipped with a function to measure the amount of electricity from each source. [Figure 9] This figure shows a graph summarizing the simulation results of the integrated power calculation values ​​by source for the hybrid energy storage system shown in Figure 8 and the tri-hybrid battery storage system shown in Figure 4. [Modes for carrying out the invention]

[0013] Figure 1 shows the basic configuration of a tri-hybrid energy storage system. A tri-hybrid energy storage system is also called a V2H energy storage system, and a solar cell 6, a stationary battery 7, and an on-board battery 8 are connected to a power conversion system 1.

[0014] The power conversion system 1 includes an inverter 12, a first DC / DC converter 11a, a second DC / DC converter 11b, a third DC / DC converter 11c, and a control unit 13. The power conversion system 1 is a storage battery-linked power conditioner. The second DC / DC converter 11b is a charge-discharge converter for the stationary storage battery 7, and may be built into the power conditioner, or may be externally attached to the DC bus Bd of the power conditioner. The third DC / DC converter 11c is a V2H converter for the on-vehicle storage battery 8, and may be built into the power conditioner, or may be externally attached to the DC bus Bd of the power conditioner.

[0015] The solar cell 6 utilizes the photovoltaic effect and can directly convert light energy into DC power. As the solar cell 6, silicon solar cells, solar cells made of materials such as compound semiconductors, dye-sensitized solar cells, organic thin-film solar cells, and the like are used. The solar cell 6 is connected to the first DC / DC converter 11a, and outputs the generated electric power to the first DC / DC converter 11a. The first DC / DC converter 11a is connected between the solar cell 6 and the DC bus Bd, and is a converter capable of adjusting the voltage of the DC power output from the solar cell 6. For example, the first DC / DC converter 11a can be configured by a step-up chopper.

[0016] The stationary storage battery 7 is capable of charging and discharging electric power, and is configured of a lithium-ion storage battery, a nickel-metal hydride storage battery, or the like. The stationary storage battery 7 is connected to the second DC / DC converter 11b, and is subjected to charge-discharge control by the second DC / DC converter 11b. The second DC / DC converter 11b is connected between the stationary storage battery 7 and the DC bus Bd, and is a bidirectional DC / DC converter that charges and discharges the stationary storage battery 7.

[0017] The on-vehicle battery 8 is a driving battery mounted on an electric vehicle, and is configured of a lithium-ion battery, a nickel-hydrogen battery, or the like. The electric vehicle and the power conversion system 1 are connected via a charging cable. The on-vehicle battery 8 is connected to the third DC / DC converter 11c when the electric vehicle is parked at home, and charge and discharge thereof are controlled by the third DC / DC converter 11c. The third DC / DC converter 11c is a bidirectional DC / DC converter connected between the on-vehicle battery 8 and the DC bus Bd, and configured to charge and discharge the on-vehicle battery 8 when the electric vehicle is parked at home.

[0018] Note that stationary or on-vehicle storage batteries can also be replaced with supercapacitors such as electric double layer capacitors and lithium ion capacitors. In the present specification, storage batteries and capacitors are collectively referred to as power storage units.

[0019] The inverter 12 has a DC terminal side connected to the DC bus Bd, and an AC terminal side connected to the distribution board 3. The first DC / DC converter 11a to the third DC / DC converter 11c are connected in parallel to the DC bus Bd. The inverter 12 converts DC power input via the DC bus Bd from at least one of the first DC / DC converter 11a, the second DC / DC converter 11b, and the third DC / DC converter 11c into AC power, and outputs the converted AC power to the distribution board 3. In this process, the inverter 12 can control the voltage or current of the output AC power.

[0020] Furthermore, the inverter 12 can also convert AC power supplied from the commercial power system 2 (hereinafter simply referred to as the system 2) via the distribution board 3 into DC power, and output the converted DC power to the DC bus Bd. The system 2 and an in-house load 4 are connected to the distribution board 3. The in-house load 4 is a general term for loads installed in a house.

[0021] It is desirable that the first DC / DC converter 11a to the third DC / DC converter 11c and the inverter 12 have the same or as close conversion efficiency as possible.

[0022] The control unit 13 controls the entire power conversion system 1. The control unit 13 can be realized through the collaboration of hardware and software resources, or solely through hardware resources. Hardware resources that can be used include analog circuits, logic circuits, microcontrollers, DSPs, ROMs, RAMs, ASICs, FPGAs, and other LSIs. Software resources that can be used include programs such as firmware.

[0023] The control unit 13 performs Maximum Power Point Tracking (MPPT) control of the solar cell 6 by controlling the first DC / DC converter 11a. Specifically, the control unit 13 measures the input voltage and input current of the first DC / DC converter 11a, which are the output voltage and output current of the solar cell 6, and estimates the power generated by the solar cell 6. Based on the measured output voltage of the solar cell 6 and the estimated power generated, the control unit 13 generates a voltage command value to set the power generated by the solar cell 6 to its maximum power point (optimal operating point). For example, the control unit 13 searches for the maximum power point by changing the operating point voltage in predetermined step widths according to the hill-climbing method, and generates a voltage command value to maintain the maximum power point. The first DC / DC converter 11a switches in response to a drive signal based on the generated voltage command value.

[0024] The control unit 13 controls the second DC / DC converter 11b to control the charging and discharging of the stationary battery 7. Based on the current command value or voltage command value set by the control unit 13, the second DC / DC converter 11b performs constant current (CC) discharge, constant voltage (CV) discharge, constant current charge, or constant voltage charge of the stationary battery 7. When operating the stationary battery 7 to track at least one of the power generation amount of the solar cell 6 and the power consumption amount of the household load 4, the control unit 13 generates the current command value for the second DC / DC converter 11b according to the voltage of the DC bus Bd.

[0025] The control unit 13 can control the charging and discharging of the on-board battery 8 by controlling the third DC / DC converter 11c. The control unit 13 can communicate with the BMU (Battery Management Unit) of the on-board battery 8 via the communication line in the charging cable. In the case of CHAdeMO (registered trademark), the connection is made via CAN (Controller Area Network). The third DC / DC converter 11c performs constant current discharge, constant voltage discharge, constant current charge, or constant voltage charge of the on-board battery 8 based on the current command value or voltage command value set by the control unit 13 or the BMU of the on-board battery 8.

[0026] The control unit 13 controls the inverter 12 so that the voltage of the DC bus Bd maintains a target value. Specifically, the control unit 13 measures the voltage of the DC bus Bd and generates a current command value to match the measured bus voltage to the target value. If the voltage of the DC bus Bd is higher than the target value, the control unit 13 generates a current command value to increase the output power of the inverter 12, and if the voltage of the DC bus Bd is lower than the target value, it generates a current command value to decrease the output power of the inverter 12. The inverter 12 switches according to the drive signal based on the generated current command value.

[0027] A smart meter 5 is connected between system 2 and distribution board 3. The smart meter 5 is equipped with a voltage sensor and a current sensor, and measures power by multiplying the system voltage measured by the voltage sensor with the current measured by the current sensor. The smart meter 5 can measure the cumulative amount of power at predetermined intervals (for example, every 30 minutes). It can measure both forward and reverse power flow. The cumulative amount of power measured by the smart meter 5 is used as basic data for calculating electricity rates by retail electricity providers. It is also used as basic data for calculations when selling solar power generation to power companies and aggregators.

[0028] Prior to the enforcement of the Energy Supply Resilience Act in April 2022, in order for a PPA operator to bill a customer for electricity consumed by the customer's home load 4, it was necessary to install a separate smart meter 5a for the PPA operator between the power conversion system 1 and the distribution board 3. The smart meter 5a is equipped with communication functions and can transmit the cumulative amount of electricity to the PPA operator server 10 at predetermined intervals (for example, every 30 minutes) via the network 9. Although not shown in Figure 1, the smart meter 5 installed between the grid 2 and the distribution board 3 can also transmit the cumulative amount of electricity to the retail electricity provider server at predetermined intervals via the network 9.

[0029] Following the enforcement of the Energy Supply Resilience Act in April 2022, instead of installing a smart meter 5a between the power conversion system 1 and the distribution board 3, it became permissible to use the amount of electricity measured by a power conditioner that meets the conditions stipulated in the guidelines for specific measurement systems as the basic data for calculating electricity rates.

[0030] The guidelines concerning the specified measurement system issued by the Agency for Natural Resources and Energy in April 2022 state that, regarding the separation of power sources for multi-input power conditioners, "if the impact of proportional measurement can be limited by devising methods of proportional allocation, the impact should be explained to the counterparty to the transaction involving the specified measurement, and if the impact is comparable to the accuracy permitted by the specified measurement, it can be subject to this system."

[0031] Figure 2 shows a table of tolerance classes according to transaction scale, as indicated in the guidelines for the specified measurement system. The guidelines state: "Notifiers should, in principle, select a tolerance (Note) from range A in the table when conducting specified measurements, according to the transaction scale. If a tolerance from range B in the table is selected for a transaction, it is required that the notifier fulfills a more thorough accountability than when conducting specified measurements within range A, such as explaining to the other party to the transaction regarding the specified measurement the specific impact (amount, etc.) that the error of the electrical meter will have on the transaction." (Note) Tolerance refers to the allowable difference expressed as the absolute value of the error (the ratio of the value obtained by subtracting the true value from the measured value to that true value). In these guidelines, tolerance refers to the allowable difference of the lead scale error. (Lead scale error is the concept of what percentage error there is relative to the displayed value, regardless of the magnitude of the measured value.)"

[0032] The guidelines also state that "Under this system, the tolerance during pre-use inspections, etc., which can be selected by the notifier, is divided into seven stages from 0.5 to 8.0%, and the tolerance during use is divided into seven stages from 0.9 to 10%. The notifier shall select the appropriate tolerance according to the scale of the transaction. Electrical measuring instruments with errors larger than these cannot be used for specified measurements."

[0033] n3 class (with a tolerance of 3.0% during use) corresponds to the tolerance of a typical smart meter. n2 class (with a tolerance of 1.7% during use) corresponds to the tolerance of a high-precision smart meter.

[0034] Figure 3 is an explanatory diagram regarding the handling of proportional measurement under the specified measurement system, published on the website of the Agency for Natural Resources and Energy. The website of the Agency for Natural Resources and Energy states, "As shown in the above diagram, if a certified specified measuring instrument, such as an electricity meter, is installed, and transactions are conducted by proportionally allocating the amount of electricity generated from G1 = meter M × meter m1 / (meter m1 + meter m2) and the amount of electricity generated from G2 = meter M × meter m2 / (meter m1 + meter m2), then, if the following conditions are met, it is considered that the obligation to make efforts toward accurate measurement required by the Measurement Act has been fulfilled, and proportional measurement can be carried out appropriately." The conditions necessary to fulfill the obligation to make efforts toward accurate measurement are stated as follows: (1) the timing of meter readings for each measuring instrument is synchronized, and (2) the wiring is such that proportional measurement can be carried out appropriately.

[0035] In the configuration shown in Figure 3, When the tolerances of meter M, meter m1, and meter m2 are 3%, the tolerances of the energy derived from G1 and the tolerances of the energy derived from G2 are both 3%. When the tolerance of meter M is 3%, the tolerance of meter m1 is -3%, and the tolerance of meter m2 is -3%, the tolerances of the energy derived from G1 and the tolerances of the energy derived from G2 are both 3%. When the tolerances of meter M = 3%, meter m1 = 3%, and meter m2 = -3%, the tolerance for the energy derived from G1 will be -3% to 3%, and the tolerance for the energy derived from G2 will be 3% to 9.37%. The tolerance for the energy derived from G2 will be 3% when the ratio of energy derived from G1 is at its maximum, and 9.37% when the ratio of energy derived from G1 is at its minimum. When the tolerance of meter M is 3%, the tolerance of meter m1 is -3%, and the tolerance of meter m2 is 3%, the tolerance of the energy derived from G1 is 3% to 9.37%, and the tolerance of the energy derived from G2 is -3% to 3%. The tolerance of the energy derived from G1 is 9.37% when the proportion of energy derived from G1 is at its maximum, and 3% when the proportion of energy derived from G1 is at its minimum.

[0036] The above method of proportional measurement assumes that no power loss occurs between meter m1 and meter M, and between meter m2 and meter M. In this embodiment, we will explain a mechanism for measuring the amount of electricity by origin within the tolerance range permitted by the specific measurement system, using the proportional measurement method permitted by the specific measurement system.

[0037] Figure 4 shows the configuration of a tri-hybrid energy storage system equipped with a function to measure the amount of electricity from each source. In order to measure DC power with high accuracy using the multi-input power conversion system 1, it is necessary to consider the conversion losses of the inverter 12, the first DC / DC converter 11a, the second DC / DC converter 11b, and the third DC / DC converter 11c.

[0038] In the embodiment shown in Figure 4, measurement points are set before and after the inverter 12, the first DC / DC converter 11a, the second DC / DC converter 11b, and the third DC / DC converter 11c, respectively, in order to ensure that the proportion of power-derived components does not change and to absorb the above-mentioned conversion losses.

[0039] AC power meter 14 is installed between inverter 12 and distribution board 3. First DC power meter 151 is installed between inverter 12 and junction N1 of DC bus Bd. Second DC power meter 152 is installed between junction N1 of DC bus Bd and first DC / DC converter 11a. Third DC power meter 153 is installed between first DC / DC converter 11a and solar cell 6. Fourth DC power meter 154 is installed between junction N1 of DC bus Bd and second DC / DC converter 11b. Fifth DC power meter 155 is installed between second DC / DC converter 11b and stationary battery 7. Sixth DC power meter 156 is installed between junction N1 of DC bus Bd and third DC / DC converter 11c. Seventh DC power meter 157 is installed between third DC / DC converter 11c and on-board battery 8.

[0040] The AC power meter 14 and the first DC power meter 151-7th DC power meter 157 are each equipped with a voltage sensor and a current sensor. The power value is obtained by multiplying the voltage value measured by the voltage sensor by the current value measured by the current sensor. The voltage and current sensors used for metering for billing purposes and the voltage and current sensors used for controlling the inverter 12 and DC / DC converters 11a-11c are basically installed separately, but some may be shared. In this embodiment, the AC power meter 14 and the first DC power meter 151-7th DC power meter 157 are each designed to meet the requirements of a specific meter that fits within the n2 or n3 class tolerance shown in Figure 2. In the tri-hybrid energy storage system according to this embodiment shown in Figure 4, the smart meter 5a between the power conversion system 1 and the distribution board 3 shown in Figure 1 is omitted.

[0041] The control unit 13 can calculate the power values ​​for each measurement point based on their respective origins, using the power measured by the AC power meter 14 and the first DC power meter 151 to the seventh DC power meter 157. Finally, the control unit 13 can measure the amount of power originating from the solar cell 6 output from the power conversion system 1 to the distribution board 3. The power for each measurement point is defined below.

[0042] Figure 5 is a diagram defining the power at each measurement point of the power conversion system 1 shown in Figure 4, and the amount of energy stored in the stationary battery 7 by source. The source of the energy stored in the stationary battery 7 (remaining capacity) is classified into solar cell 6 (PV), grid 2, and others. Others is the amount of energy charged from the on-board battery 8. The amount of energy stored in the on-board battery 8 may include power charged from an externally installed charger while the electric vehicle is out. Since it is difficult to strictly control the source of the energy stored in the on-board battery 8, in this embodiment, the source of the energy stored in the on-board battery 8 is not classified, and it is all categorized as others. Therefore, the power charged from the solar cell 6 to the on-board battery 8 and discharged from the on-board battery 8 for self-consumption is excluded from the claim.

[0043] (1) Reverse flow power The power output from distribution board 3 to system 2, as measured by smart meter 5. (2) Forward flow power The power output from system 2 to distribution board 3, as measured by smart meter 5. (3) System output power The power output from the power conversion system 1 to the distribution board 3, as measured by the AC power meter 14. (4) System purchased electricity The power output from the distribution board 3 to the power conversion system 1, as measured by the AC power meter 14. (5) Bus output power The power output from the confluence point N1 of the DC bus Bd to the inverter 12, as measured by the first DC power meter 151. (6) Bus purchased electricity The power output from inverter 12 to the junction point N1 of DC bus Bd, as measured by the first DC power meter 151. (7) PV bus power generation The power output from the first DC / DC converter 11a to the junction point N1 of the DC bus Bd, as measured by the second DC power meter 152. (8) PV power generation The power output from the solar cell 6 to the first DC / DC converter 11a, as measured by the third DC power meter 153. (9) SB bus discharge power The power output from the second DC / DC converter 11b to the junction point N1 of the DC bus Bd, as measured by the fourth DC power meter 154. (10) SB bus charging power The power output from the confluence point N1 of the DC bus Bd to the second DC / DC converter 11b, as measured by the fourth DC power meter 154. (11)SB discharge power The power output from the stationary battery 7 to the second DC / DC converter 11b, as measured by the fifth DC power meter 155. (12)SB charging power The power output from the second DC / DC converter 11b to the stationary battery 7, as measured by the fifth DC power meter 155. (13) EV bus discharge power The power output from the third DC / DC converter 11c to the junction point N1 of the DC bus Bd, as measured by the sixth DC power meter 156. (14) EV bus charging power The power output from the confluence point N1 of the DC bus Bd to the third DC / DC converter 11c, as measured by the sixth DC power meter 156. (15)EV discharge power The power output from the onboard battery 8 to the third DC / DC converter 11c, as measured by the seventh DC power meter 157. (16)EV charging power The power output from the third DC / DC converter 11c to the on-board battery 8, as measured by the seventh DC power meter 157. (17) Amount of PV-derived electricity stored in the stationary battery 7 (18) Amount of grid-derived electricity stored in the stationary battery 7 (19) Amount of other-sourced electricity stored in the stationary battery 7

[0044] Figure 6 is a diagram that organizes the power at each measurement point of the power conversion system 1 shown in Figure 5 into input power to the DC bus Bd and output power from the DC bus Bd. For (3) system output power, (5) bus output power, (9) SB bus discharge power, (10) SB bus charge power, (11) SB discharge power, (12) SB charge power, (14) EV bus charge power, and (16) EV charge power, it is also defined whether the power is derived from PV, grid, or other sources.

[0045] (3) PV-derived system output power The power originating from the solar cell 6, which is output from the power conversion system 1 to the distribution board 3, as measured by the AC power meter 14. (3) System Grid System output power Power originating from grid 2, output from power conversion system 1 to distribution board 3, as measured by AC power meter 14. (3) Others Other Origin System Output Power Other sources of power output from power conversion system 1 to distribution board 3, as measured by AC power meter 14. (5) PV-derived bus output power Power originating from the solar cell 6, output to the inverter 12 from the confluence point N1 of the DC bus Bd, as measured by the first DC power meter 151. (5) System System-derived bus output power Power originating from grid 2, output to inverter 12 from the junction N1 of DC bus Bd, as measured by the first DC power meter 151. (5) Other Bus output power from other sources Power from other sources, output to inverter 12 from the confluence point N1 of DC bus Bd, as measured by the first DC power meter 151. (9) PV-derived SB bus discharge power Power originating from the solar cell 6, output from the second DC / DC converter 11b to the junction point N1 of the DC bus Bd, as measured by the fourth DC power meter 154. (9) System SB bus discharge power originating from the system Power originating from grid 2, output from the second DC / DC converter 11b to the junction N1 of the DC bus Bd, as measured by the fourth DC power meter 154. (9) Other SB bus discharge power from other sources Power from other sources, output from the second DC / DC converter 11b to the junction point N1 of the DC bus Bd, as measured by the fourth DC power meter 154. (10) PV-derived SB bus charging power Power originating from the solar cell 6, output from the confluence point N1 of the DC bus Bd, as measured by the fourth DC power meter 154, to the second DC / DC converter 11b. (10) System SB bus charging power derived from the system Power originating from grid 2, output from the confluence point N1 of DC bus Bd to the second DC / DC converter 11b, as measured by the fourth DC power meter 154. (10) Other Other Sources of SB Bus Charging Power Power from other sources, output from the confluence point N1 of the DC bus Bd to the second DC / DC converter 11b, as measured by the fourth DC power meter 154. (11) PV-derived SB discharge power Power originating from the solar cell 6, output from the stationary battery 7 to the second DC / DC converter 11b, as measured by the fifth DC power meter 155. (11) System SB discharge power originating from the system Power originating from grid 2, output from stationary battery 7 to second DC / DC converter 11b, as measured by the fifth DC power meter 155. (11) Other Other Sources of SB Discharge Power Power from other sources, output from the stationary battery 7 to the second DC / DC converter 11b, as measured by the fifth DC power meter 155. (12) PV-derived SB charging power Power originating from the solar cell 6, output from the second DC / DC converter 11b to the stationary battery 7, as measured by the fifth DC power meter 155. (12) Grid-derived SB charging power Power originating from grid 2, output from the second DC / DC converter 11b to the stationary battery 7, as measured by the fifth DC power meter 155. (12) Other Other Sources of SB Charging Power Power from other sources, output from the second DC / DC converter 11b to the stationary battery 7, as measured by the fifth DC power meter 155. (14) PV-derived EV bus charging power Power originating from the solar cell 6, output from the confluence point N1 of the DC bus Bd, as measured by the 6th DC power meter 156, to the 3rd DC / DC converter 11c. (14) PV-derived grid bus charging power Power originating from grid 2, output from the confluence point N1 of DC bus Bd to the third DC / DC converter 11c, as measured by the sixth DC power meter 156. (14) Others Other sources of EV bus charging power Power from other sources, output from the confluence point N1 of the DC bus Bd to the third DC / DC converter 11c, as measured by the sixth DC power meter 156. (16) PV-derived EV charging power Power originating from the solar cell 6, output from the third DC / DC converter 11c to the on-board battery 8, as measured by the seventh DC power meter 157. (16) Grid-derived EV charging power Power originating from grid 2, output from the 3rd DC / DC converter 11c to the on-board battery 8, as measured by the 7th DC power meter 157. (16) Other EV charging power from other sources Power from other sources, output from the 3rd DC / DC converter 11c to the on-board battery 8, as measured by the 7th DC power meter 157.

[0046] (4) The source of the system's purchased power and (6) the bus's purchased power is fixed to grid 2. (7) The source of the PV bus's generated power and (8) the PV's generated power is fixed to solar cell 6. (13) The source of the EV bus's discharged power and (15) the EV discharged power is fixed to other sources.

[0047] (6) Bus purchased power, (7) PV bus generated power, (9) SB bus discharge power, and (13) EV bus discharge power are mixed in the DC bus Bd, but the component ratio of the DC bus Bd is considered to be the ratio of the amount of energy injected. The origins of (3) system output power, (5) bus output power, (9) SB bus discharge power, (11) SB discharge power, (10) SB bus charging power, (12) SB charging power, (14) EV bus charging power, and (16) EV charging power are allocated and separated using the ratio of the amount of energy injected into the DC bus Bd.

[0048] (17) The amount of PV-derived electricity stored in the stationary battery 7, (18) the amount of grid-derived electricity stored in the stationary battery 7, and (19) the amount of other-derived electricity stored in the stationary battery 7 shall be considered as the actual remaining capacity stored at each point in time, not as an accumulated value over 30 minutes.

[0049] The inverter 12, the second DC / DC converter 11b, and the third DC / DC converter 11c are assumed to operate in only one direction at each point in time.

[0050] Figure 7 is a graph summarizing the calculation algorithm for power values ​​by source. (17) The initial values ​​for the amount of power derived from PV stored in the stationary battery 7 and (18) the amount of power derived from the grid stored in the stationary battery 7 are set to 0. (19) The initial value for the amount of power from other sources stored in the stationary battery 7 is set to the remaining capacity of the stationary battery 7 at the time of the initial startup of the power conversion system 1.

[0051] The formulas for calculating the power values ​​by source for (3) system output power, (5) bus output power, (9) SB bus discharge power, (10) SB bus charge power, (11) SB discharge power, (12) SB charge power, (14) EV bus charge power, and (16) EV charge power are as follows.

[0052] (11)_PV=(11)*(17) / [(17)+(18)+(19)]···(Formula 1) (11)_System=(11)*(18) / [(17)+(18)+(19)]···(Formula 2) (11)_Others = (11)*(19) / [(17)+(18)+(19)]···(Equation 3) (9)_PV=(9)*(11)_PV / (11) (Formula 4) (9)_system=(9)*(11)_system / (11)...(Equation 5) (9)_Other = (9) * (11)_Other / (11) ... (Equation 6) (5)_PV=(5)*[(7)+(9)_PV] / [(7)+(9)+(13)]...(Formula 7) (5)_system=(5)*(9)_system / [(7)+(9)+(13)]···(Equation 8) (5)_Others = (5) * [(9)_Others + (13)] / [(7) + (9) + (13)] ... (Equation 9) (10)_PV=(10)*(7) / [(7)+(6)+(13)]···(Formula 10) (10)_System=(10)*(6) / [(7)+(6)+(13)]···(Formula 11) (10)_Others = (10)*(13) / [(7)+(6)+(13)]···(Equation 12) (12)_PV=(12)*(10)_PV / (10) (Equation 13) (12)_system=(12)*(10)_system / (10)...(Equation 14) (12)_Other = (12)*(10)_Other / (10)···(Equation 15) (14)_PV=(14)*[(7)+(9)_PV] / [(6)+(7)+(9)] (Equation 16) (14)_system=(14)*[(6)+(9)_system / [(6)+(7)+(9)]...(Equation 17) (14)_Other = (14)*(9)_Other / [(6)+(7)+(9)]···(Equation 18) (16)_PV=(16)*(14)_PV / (14) (Equation 19) (16)_system=(16)*(14)_system / (14)...(Equation 20) (16)_Other = (16)*(14)_Other / (14)···(Equation 21) (3)_PV=(3)*(5)_PV / (5) (Equation 22) (3)_system=(3)*(5)_system / (5)...(Equation 23) (3)_Other = (3)*(5)_Other / (5)···(Equation 24)

[0053] The formulas for calculating (17) the amount of electricity from PV stored in the stationary battery 7, (18) the amount of electricity from the grid stored in the stationary battery 7, and (19) the amount of electricity from other sources stored in the stationary battery 7 are as follows.

[0054] (17)=(17)+(12)_PV-(9)_PV...(Equation 25) (18)=(18)+(12)_system-(9)_system...(Equation 26) (19) = (19) + (12) - (9) - (Equation 27)

[0055] The control unit 13 integrates the measured values ​​of (3) system output power, (4) system purchased power, (5) bus output power, (6) bus purchased power, (7) PV bus generated power, (8) PV generated power, (9) SB bus discharge power, (10) SB bus charging power, (11) SB discharge power, (12) SB charging power, (13) EV bus discharge power, (14) EV bus charging power, (15) EV discharge power, and (16) EV charging power to calculate the 30-minute integrated value of each power measurement. Each integrated value is cleared every 30 minutes.

[0056] The control unit 13 calculates the 30-minute cumulative value of each power source by integrating the calculated values ​​of (9)_PV SB bus discharge power originating from PV, (9)_system SB bus discharge power originating from the system, (9)_other SB bus discharge power originating from other sources, (12)_PV SB charging power originating from PV, (12)_system SB charging power originating from the system, (12)_other SB charging power originating from other sources, (16)_PV EV charging power originating from PV, (16)_system EV charging power originating from the system, (16)_other EV charging power originating from other sources, (3)_PV system output power, (3)_system system output power originating from the system, and (3)_other system output power originating from other sources. Each cumulative value is cleared every 30 minutes.

[0057] As shown in (Equation 25) above, the control unit 13 adds the SB charging power derived from (12)_PV PV to the amount of PV-derived energy stored in (17) the stationary battery 7, and subtracts the SB bus discharge power derived from (9)_PV PV from the amount of PV-derived energy stored in (17) the stationary battery 7, thereby managing the current value of the amount of PV-derived energy stored in (17) the stationary battery 7.

[0058] As shown in (Equation 1) above, the control unit 13 calculates the ratio of the remaining capacity derived from the solar cell 6 to the total remaining capacity of the stationary battery 7, and multiplies this by the discharge power value measured by the fifth DC power meter 155 to calculate the discharge power value derived from the solar cell 6 measured by the fifth DC power meter 155.

[0059] As shown in (Equation 4) above, the control unit 13 calculates the discharge power value originating from the solar cell 6 measured by the fourth DC wattmeter 154 by multiplying the discharge power value measured by the fourth DC wattmeter 154 by the ratio of the discharge power value originating from the solar cell 6 measured by the fifth DC wattmeter 155 to the discharge power value measured by the fifth DC wattmeter 155.

[0060] As shown in (Equation 7) above, the control unit 13 calculates the ratio of the sum of the generated power value measured by the second DC wattmeter 152 and the discharge power value from the solar cell 6 measured by the fourth DC wattmeter 154 to the sum of the generated power value measured by the second DC wattmeter 152, the discharge power value measured by the fourth DC wattmeter 154, and the discharge power value measured by the sixth DC wattmeter 156. The control unit 13 multiplies this ratio by the bus output power value measured by the first DC wattmeter 151 to calculate the bus output power value from the solar cell 6 measured by the first DC wattmeter 151.

[0061] As shown in (Equation 22) above, the control unit 13 calculates the system output power value originating from the solar cell 6 measured by the AC power meter 14 by multiplying the system output power value measured by the AC power meter 14 by the ratio of the bus output power value originating from the solar cell 6 measured by the first DC power meter 151 to the bus output power value measured by the first DC power meter 151.

[0062] The PPA operator can use the integrated system output power value derived from the solar cell 6 as basic data when billing for electricity consumed by the household load 4. The PPA operator can also use the integrated EV charging power value derived from the solar cell 6, as shown in (Equation 19) above, as basic data when billing for electricity consumed by the electric vehicle. Furthermore, the integrated EV charging power value derived from grid 2, as shown in (Equation 20) above, can be used as the amount of electricity charged to the electric vehicle from grid 2.

[0063] If the tolerance of the power measured at the measurement points by the first DC power meter 151 to the seventh DC power meter 157 is within n3 class (3%), the apportionment of the power charged to the stationary battery 7 will always be within -3% to +3%.

[0064] The term (17) / [(17)+(18)+(19)] in the above (Equation 1) is the ratio of the power measured by the same 7th DC wattmeter 157. For example, if the tolerance of the 7th DC wattmeter 157 is 3%, then a*1.03 / (a*1.03+b*1.03+c*1.03)=a*1.03 / (a+b+c)*1.03=a / (a+b+c), and the errors of the 7th DC wattmeter 157 cancel each other out. Therefore, the measurement error of (11) SB discharge power becomes the error of the apportioned power.

[0065] Figure 8 shows the configuration of a hybrid energy storage system equipped with a function to measure the amount of electricity from each source. In the hybrid energy storage system, the on-board battery 8 is not connected to the power conversion system 1, and the third DC / DC converter 11c, the sixth DC wattmeter 156, and the seventh DC wattmeter 157 are omitted. In the hybrid energy storage system, in the calculation algorithm for the amount of electricity from each source shown in Figure 7, (13) EV bus discharge power, (14) EV bus charging power, (15) EV discharge power, and (16) EV charging power are omitted. (19) The amount of electricity from other sources stored in the stationary battery 7 is also omitted, and the amount of electricity stored in the stationary battery 7 is the sum of the amount of electricity from PV and the amount of electricity from the grid.

[0066] Figure 9 is a graph summarizing the simulation results of the integrated power calculation values ​​by source for the hybrid energy storage system shown in Figure 8 and the tri-hybrid battery storage system shown in Figure 4. When the tolerance of the power at the measurement points measured by the first DC wattmeter 151 to the fifth DC wattmeter 155 is within n3 class, the integrated power calculation values ​​by source in the hybrid energy storage system shown in Figure 8 will have an error equivalent to n5 class. When the tolerance of the power at the measurement points measured by the first DC wattmeter 151 to the fifth DC wattmeter 155 is within n2 class, the integrated power calculation values ​​by source in the hybrid energy storage system shown in Figure 8 will have an error equivalent to n3 class.

[0067] In the simulation, for a 6kW rated hybrid energy storage system with n3 class tolerances for each DC measurement point, the maximum error in actual use occurred in the following cases: when the solar cell 6 generates 1.8kW and the stationary battery 7 discharges 3.6kW; when the solar cell 6 generates 1.8kW and the stationary battery 7 discharges 3.0kW; when the solar cell 6 generates 1.2kW and the stationary battery 7 discharges 2.4kW; and when the solar cell 6 generates 0.6kW and the stationary battery 7 discharges 1.2kW. The error was 4.67%.

[0068] If the tolerance of the power at the measurement points measured by the first DC wattmeter 151 to the seventh DC wattmeter 157 is within n3 class, the cumulative value of the power calculations by source in the tri-hybrid energy storage system shown in Figure 4 will have an error equivalent to n6 class. If the tolerance of the power at the measurement points measured by the first DC wattmeter 151 to the seventh DC wattmeter 157 is within n2 class, the cumulative value of the power calculations by source in the tri-hybrid energy storage system shown in Figure 4 will have an error equivalent to n4 class.

[0069] In the simulation, in a tri-hybrid energy storage system with a rating of 6kW and a tolerance of n3 class for each DC measurement point, the maximum error in actual use occurred when the power generated by solar cell 6 was 0.0kW and the ratio of discharge power of stationary battery 7 to discharge power of vehicle battery 8 was 50:50, with the error being 6.09%.

[0070] In either case, the tolerance falls approximately within range A for transaction scales of 10kW or less, as shown in the tolerance class table in Figure 2. Thus, the hybrid energy storage system or tri-hybrid energy storage system according to this embodiment is a system that enables electricity trading within tolerance range A, which is permitted under the specific measurement system, using the apportionment measurement method permitted under the specific measurement system.

[0071] As described above, according to this embodiment, in a hybrid energy storage system or a tri-hybrid energy storage system, n2 class or n3 class specific meters are installed before and after the inverter and DC / DC converter, and the power values ​​by origin at each measurement point and the remaining capacity of the stationary battery 7 by origin are calculated as shown in (Equation 1)-(Equation 27) above. This makes it possible to eliminate the effects of conversion losses by the inverter and DC / DC converter with high precision, and to identify the proportion of the origin component at each measurement point with high precision. Therefore, it is possible to measure the amount of power by origin that satisfies the tolerance conditions in the guidelines for specific measurement systems. In a hybrid energy storage system or a tri-hybrid energy storage system, the PPA operator will be able to charge the customer for the electricity charges for the portion of solar power generation used for self-consumption on a metered basis.

[0072] Incidentally, Japan has the J-Credit Scheme, in which the government certifies greenhouse gas emission reductions or intake amounts as credits. In the J-Credit Scheme, the charge and discharge loss amount in storage batteries is defined as follows (Equation 28). Charge / discharge loss (kWh / year) = Self-consumption (kWh / year) × Battery transfer rate (%) × (1 - Charging efficiency (%) / 100 (%) × Discharge efficiency (%) / 100 (%)) ... (Equation 28)

[0073] The amount of electricity (kWh / year) transmitted through the battery is calculated by multiplying the default value by 60% if the battery capacity is 4kWh or less, and by 70% if it is greater than 4kWh. Furthermore, the charge / discharge efficiency (%) should be determined from the battery's catalog, specifications, etc. If this information is unavailable, the default value (90% for both charge and discharge efficiency) should be used.

[0074] Because the conditions are set strictly to avoid putting J-Credit at a disadvantage, the amount of electricity consumed by solar power generation via storage batteries is only recognized as environmentally valuable for less than the actual amount used. By adopting the amount of electricity consumed by solar power generation calculated using the calculation algorithm of this embodiment, it becomes possible to recognize environmental value that is in line with the actual amount used.

[0075] The present disclosure has been described above based on embodiments. The embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

[0076] In the above embodiment, an example was described in which a solar cell 6 is used as a power generation device that converts renewable energy into electrical energy. However, a wind turbine or a micro-hydroelectric generator can also be used instead of the solar cell 6. In this case, a rectifier is connected between the wind turbine or micro-hydroelectric generator and the first DC / DC converter 11a.

[0077] The embodiments may be specified by the following items.

[0078] [Item 1] A first DC / DC converter (11a) is connected to a power generation device (6) that converts renewable energy into electrical energy, A second DC / DC converter (11b) is connected to the stationary energy storage unit (7), The DC terminal side of the inverter (12) is connected to the junction point (N1) of the first DC / DC converter (11a) and the second DC / DC converter (11b), and the AC terminal side is connected to a distribution board (3) which is connected to the grid (2) and load (4). An AC power meter (14) is installed between the inverter (12) and the distribution board (3), A first DC power meter (151) is installed between the inverter (12) and the confluence point (N1), A second DC power meter (152) is installed between the aforementioned junction point (N1) and the first DC / DC converter (11a), A third DC power meter (153) is installed between the first DC / DC converter (11a) and the power generator (6), A fourth DC power meter (154) is installed between the aforementioned junction point (N1) and the second DC / DC converter (11b), A fifth DC power meter (155) is installed between the second DC / DC converter (11b) and the stationary energy storage unit (7), The system includes a control unit (13) that measures the amount of power originating from the power generator (6) output to the distribution board (3) based on the power measured by the AC power meter (14) and the first DC power meter (151) to the fifth DC power meter (155), respectively. Power conversion system (1). According to this, in a hybrid configuration, the amount of electricity originating from the power generation device (6) output to the distribution board (3) can be measured with high precision. [Item 2] The control unit (13) Based on the power output from the inverter (12) to the confluence point (N1) as measured by the first DC power meter (151), the power output from the first DC / DC converter (11a) to the confluence point (N1) as measured by the second DC power meter (152), and the power output from the second DC / DC converter (11b) to the stationary energy storage unit (7) as measured by the fifth DC power meter (155), the power originating from the power generator (6) and the power originating from the grid (2) that are charged to the stationary energy storage unit (7) are calculated. The power generated by the power generator (6) that is charged into the stationary energy storage unit (7) is added to the amount of power generated by the power generator (6) stored in the stationary energy storage unit (7). The power from the grid (2) that is charged to the stationary energy storage unit (7) is added to the amount of power from the grid (2) stored in the stationary energy storage unit (7). Based on the amount of electricity from the power generator (6) stored in the stationary energy storage unit (7), the amount of electricity from the grid (2), the power output from the stationary energy storage unit (7) to the second DC / DC converter (11b) as measured by the fifth DC power meter (155), and the power output from the second DC / DC converter (11b) to the confluence point (N1) as measured by the fourth DC power meter (154), the power from the power generator (6) and the power from the grid (2) discharged from the stationary energy storage unit (7) are calculated. The power originating from the power generator (6) discharged from the stationary energy storage unit (7) is subtracted from the amount of power originating from the power generator (6) stored in the stationary energy storage unit (7). The power originating from the grid (2) discharged from the stationary energy storage unit (7) is subtracted from the amount of power originating from the grid (2) stored in the stationary energy storage unit (7). The power conversion system described in item 1 (1). According to this, the amount of electricity originating from the power generation device (6) and the amount of electricity originating from the grid (2) stored in the stationary energy storage unit (7) can be estimated with high accuracy. [Item 3] The control unit (13) Based on the amount of electricity originating from the power generator (6) stored in the stationary energy storage unit (7), the amount of electricity originating from the grid (2) stored in the stationary energy storage unit (7), the power output from the stationary energy storage unit (7) to the second DC / DC converter (11b) as measured by the fifth DC power meter (155), the power output from the second DC / DC converter (11b) to the confluence point (N1) as measured by the fourth DC power meter (154), the power output from the first DC / DC converter (11a) to the confluence point (N1) as measured by the second DC power meter (152), and the power output from the confluence point (N1) to the inverter (12) as measured by the first DC power meter (151), the ratio of the power originating from the power generator (6) among the power measured by the first DC power meter (151) is calculated. The power measured by the AC power meter (14) is multiplied by the ratio of the power generated by the power generator (6) to calculate the power originating from the power generator (6) that is output to the distribution board (3). The power conversion system described in item 2 (1). According to this, in a hybrid configuration, the power originating from the power generation device (6) output to the distribution board (3) can be calculated with high accuracy. [Item 4] The AC power meter (14) and the first DC power meter (151) to the fifth DC power meter (155) are specified measuring instruments. A power conversion system (1) as described in any one of items 1 to 3. According to this, in a hybrid configuration, the conditions required by the guidelines for specific metering systems can be met even without installing a smart meter between the power conversion system (1) and the distribution board (3). [Item 5] A third DC / DC converter (11c) is connected between the onboard power storage unit (8) and the merging point (N1), A sixth DC power meter (156) is installed between the aforementioned junction point (N1) and the third DC / DC converter (11c), The system further includes a seventh DC power meter (157) installed between the third DC / DC converter (11c) and the on-board power storage unit (8), The control unit (13) measures the amount of electricity originating from the power generator (6) that is output to the distribution board (3) based on the power measured by the AC power meter (14) and the first DC power meter (151) to the seventh DC power meter (157), respectively. The power conversion system described in item 1 (1). According to this, in a tri-hybrid configuration, the amount of electricity originating from the power generation device (6) output to the distribution board (3) can be measured with high precision. [Item 6] The control unit (13) Based on the power output from the inverter (12) to the confluence point (N1) as measured by the first DC power meter (151), the power output from the first DC / DC converter (11a) to the confluence point (N1) as measured by the second DC power meter (152), the power output from the third DC / DC converter (11c) to the confluence point (N1) as measured by the sixth DC power meter (156), and the power output from the second DC / DC converter (11b) to the stationary energy storage unit (7) as measured by the fifth DC power meter (155), the power originating from the power generator (6), the power originating from the grid (2), and the power originating from other sources that are charged to the stationary energy storage unit (7) are calculated. The power generated by the power generator (6) that is charged into the stationary energy storage unit (7) is added to the amount of power generated by the power generator (6) stored in the stationary energy storage unit (7). The power from the grid (2) that is charged to the stationary energy storage unit (7) is added to the amount of power from the grid (2) stored in the stationary energy storage unit (7). The power from other sources that is charged to the stationary energy storage unit (7) is added to the amount of power from other sources stored in the stationary energy storage unit (7), Based on the amount of electricity stored in the stationary energy storage unit (7) originating from the power generation device (6), the amount of electricity originating from the grid (2), the amount of electricity originating from other sources, the power output from the stationary energy storage unit (7) to the second DC / DC converter (11b) as measured by the fifth DC power meter (155), and the power output from the second DC / DC converter (11b) to the confluence point (N1) as measured by the fourth DC power meter (154), the power originating from the power generation device (6), the power originating from the grid (2), and the power originating from other sources discharged from the stationary energy storage unit (7) are calculated. The power originating from the power generator (6) discharged from the stationary energy storage unit (7) is subtracted from the amount of power originating from the power generator (6) stored in the stationary energy storage unit (7). The power originating from the grid (2) discharged from the stationary energy storage unit (7) is subtracted from the amount of power originating from the grid (2) stored in the stationary energy storage unit (7). The power discharged from the stationary energy storage unit (7) is subtracted from the amount of power stored in the stationary energy storage unit (7) that is of other origin. The power conversion system described in item 5 (1). According to this, it is possible to estimate with high accuracy the amount of electricity stored in the stationary energy storage unit (7) that originates from the power generation device (6), the amount of electricity that originates from the grid (2), and the amount of electricity that originates from other sources. [Item 7] The control unit (13) The amount of electricity from the power generator (6) stored in the stationary energy storage unit (7), the amount of electricity from the grid (2) stored in the stationary energy storage unit (7), the amount of electricity from other sources stored in the stationary energy storage unit (7), the power output from the stationary energy storage unit (7) to the second DC / DC converter (11b) as measured by the fifth DC power meter (155), and the second DC / DC converter as measured by the fourth DC power meter (154). Based on the power output from the inverter (11b) to the confluence point (N1), the power output from the first DC / DC converter (11a) to the confluence point (N1) as measured by the second DC power meter (152), and the power output from the confluence point (N1) to the inverter (12) as measured by the first DC power meter (151), the ratio of the power measured by the first DC power meter (151) that originates from the power generation device (6) is calculated. The power measured by the AC power meter (14) is multiplied by the ratio of the power generated by the power generator (6) to calculate the power originating from the power generator (6) that is output to the distribution board (3). The power conversion system described in item 6 (1). According to this, in a tri-hybrid configuration, the power originating from the power generation device (6) output to the distribution board (3) can be calculated with high accuracy. [Item 8] The AC power meter (14) and the first DC power meter (151) to the seventh DC power meter (157) are specified measuring instruments. A power conversion system (1) as described in any one of items 5 through 7. According to this, in a tri-hybrid configuration, the conditions required by the guidelines for specific metering systems can be met even without installing a smart meter between the power conversion system (1) and the distribution board (3). [Explanation of Symbols]

[0079] 1 Power conversion system, 2 grids, 3 distribution board, 4 household load, 5.5a smart meter, 6 solar panels, 7 stationary battery, 8 vehicle battery, 9 network, 10 PPA operator server, 11a first DC / DC converter, 11b second DC / DC converter, 11c third DC / DC converter, 12 inverter, 13 control unit, 14 AC power meter, 151-157 DC power meter, Bd DC bus.

Claims

1. A first DC / DC converter connected to a power generation device that converts renewable energy into electrical energy, A second DC / DC converter connected to the stationary energy storage unit, An inverter whose DC terminal side is connected to the junction point of the first DC / DC converter and the second DC / DC converter, and whose AC terminal side is connected to a distribution board connected to the grid and load, An AC power meter installed between the inverter and the distribution board, A first DC power meter is installed between the inverter and the merging point, A second DC power meter is installed between the aforementioned junction and the first DC / DC converter, A third DC power meter is installed between the first DC / DC converter and the power generation device, A fourth DC power meter is installed between the aforementioned junction and the second DC / DC converter, A fifth DC power meter is installed between the second DC / DC converter and the stationary energy storage unit, The system includes a control unit that measures the amount of power originating from the power generation device output to the distribution board, based on the power measured by the AC power meter and the first DC power meter to the fifth DC power meter, respectively. The control unit, Based on the power output from the inverter to the confluence point as measured by the first DC power meter, the power output from the first DC / DC converter to the confluence point as measured by the second DC power meter, and the power output from the second DC / DC converter to the stationary energy storage unit as measured by the fifth DC power meter, the power originating from the power generation device and the power originating from the grid that are charged to the stationary energy storage unit are calculated. The power generated by the power generation device that is charged into the stationary energy storage unit is added to the amount of power generated by the power generation device stored in the stationary energy storage unit. The power originating from the grid that is charged to the stationary energy storage unit is added to the amount of power originating from the grid that is stored in the stationary energy storage unit. Based on the amount of electricity originating from the power generation device stored in the stationary energy storage unit, the amount of electricity originating from the grid, the power output from the stationary energy storage unit to the second DC / DC converter as measured by the fifth DC power meter, and the power output from the second DC / DC converter to the confluence point as measured by the fourth DC power meter, the power originating from the power generation device and the power originating from the grid discharged from the stationary energy storage unit are calculated. The power originating from the power generation device discharged from the stationary energy storage unit is subtracted from the amount of power originating from the power generation device stored in the stationary energy storage unit. The power originating from the grid that is discharged from the stationary energy storage unit is subtracted from the amount of power originating from the grid that is stored in the stationary energy storage unit. Based on the amount of electricity originating from the power generation device stored in the stationary energy storage unit, the amount of electricity originating from the grid stored in the stationary energy storage unit, the power output from the stationary energy storage unit to the second DC / DC converter as measured by the fifth DC wattmeter, the power output from the second DC / DC converter to the merging point as measured by the fourth DC wattmeter, the power output from the first DC / DC converter to the merging point as measured by the second DC wattmeter, and the power output from the merging point to the inverter as measured by the first DC wattmeter, the ratio of the power originating from the power generation device to the power measured by the first DC wattmeter is calculated. The power measured by the AC power meter is multiplied by the ratio of power originating from the power generation device to calculate the power originating from the power generation device that is output to the distribution board. Power conversion system.

2. The AC power meter and the first DC power meter to the fifth DC power meter are specified measuring instruments. The power conversion system according to claim 1.

3. A third DC / DC converter is connected between the onboard power storage unit and the aforementioned merging point, A sixth DC power meter is installed between the aforementioned junction and the third DC / DC converter, The system further comprises a seventh DC power meter installed between the third DC / DC converter and the on-board power storage unit, The control unit measures the amount of power originating from the power generation device that is output to the distribution board, based on the power measured by the AC power meter and the first DC power meter to the seventh DC power meter, respectively. The power conversion system according to claim 1.

4. The control unit, Based on the power output from the inverter to the merging point as measured by the first DC power meter, the power output from the first DC / DC converter to the merging point as measured by the second DC power meter, the power output from the third DC / DC converter to the merging point as measured by the sixth DC power meter, and the power output from the second DC / DC converter to the stationary energy storage unit as measured by the fifth DC power meter, the power originating from the power generation device, the power originating from the grid, and the power originating from other sources that are charged to the stationary energy storage unit are calculated. The power generated by the power generation device that is charged into the stationary energy storage unit is added to the amount of power generated by the power generation device stored in the stationary energy storage unit. The power originating from the grid that is charged to the stationary energy storage unit is added to the amount of power originating from the grid that is stored in the stationary energy storage unit. The power from other sources that is charged to the stationary energy storage unit is added to the amount of power from other sources stored in the stationary energy storage unit. Based on the amount of electricity stored in the stationary energy storage unit originating from the power generation device, the amount of electricity from the grid, the amount of electricity from other sources, the power output from the stationary energy storage unit to the second DC / DC converter as measured by the fifth DC power meter, and the power output from the second DC / DC converter to the confluence point as measured by the fourth DC power meter, the power discharged from the stationary energy storage unit originating from the power generation device, the power output from the grid, and the power output from other sources are calculated. The power originating from the power generation device discharged from the stationary energy storage unit is subtracted from the amount of power originating from the power generation device stored in the stationary energy storage unit. The power originating from the grid that is discharged from the stationary energy storage unit is subtracted from the amount of power originating from the grid that is stored in the stationary energy storage unit. The power discharged from the stationary energy storage unit is subtracted from the amount of power stored in the stationary energy storage unit. The power conversion system according to claim 3.

5. The control unit, Based on the amount of electricity originating from the power generation device stored in the stationary energy storage unit, the amount of electricity originating from the grid stored in the stationary energy storage unit, the amount of electricity from other sources stored in the stationary energy storage unit, the power output from the stationary energy storage unit to the second DC / DC converter as measured by the fifth DC wattmeter, the power output from the second DC / DC converter to the merging point as measured by the fourth DC wattmeter, the power output from the first DC / DC converter to the merging point as measured by the second DC wattmeter, and the power output from the merging point to the inverter as measured by the first DC wattmeter, the ratio of the power originating from the power generation device to the power measured by the first DC wattmeter is calculated. The power measured by the AC power meter is multiplied by the ratio of power originating from the power generation device to calculate the power originating from the power generation device that is output to the distribution board. The power conversion system according to claim 4.

6. The AC power meter and the first DC power meter to the seventh DC power meter are specified measuring instruments. A power conversion system according to any one of claims 3 to 5.

7. A first DC / DC converter connected to a power generation device that converts renewable energy into electrical energy, A second DC / DC converter connected to the stationary energy storage unit, An inverter whose DC terminal side is connected to the junction point of the first DC / DC converter and the second DC / DC converter, and whose AC terminal side is connected to a distribution board connected to the grid and load, An AC power meter installed between the inverter and the distribution board, A first DC power meter is installed between the inverter and the merging point, A second DC power meter is installed between the aforementioned junction and the first DC / DC converter, A third DC power meter is installed between the first DC / DC converter and the power generation device, A fourth DC power meter is installed between the aforementioned junction and the second DC / DC converter, A fifth DC power meter is installed between the second DC / DC converter and the stationary energy storage unit, The system includes a control unit that measures the amount of power originating from the power generation device output to the distribution board, based on the AC power measured by the AC power meter and the first to fifth power measured by the first to fifth DC power meters, respectively. The control unit, Based on the first power, the second power, and the fifth power, the power generated by the power generation device and the power generated by the grid that are charged to the stationary energy storage unit are calculated. The power generated by the power generation device that is charged into the stationary energy storage unit is added to the amount of power generated by the power generation device stored in the stationary energy storage unit. The power originating from the grid that is charged to the stationary energy storage unit is added to the amount of power originating from the grid that is stored in the stationary energy storage unit. Based on the amount of electricity originating from the power generation device, the amount of electricity originating from the grid, the fifth power, and the fourth power stored in the stationary energy storage unit, the amount of electricity originating from the power generation device and the amount of electricity originating from the grid discharged from the stationary energy storage unit are calculated. The power originating from the power generation device discharged from the stationary energy storage unit is subtracted from the amount of power originating from the power generation device stored in the stationary energy storage unit. The power originating from the grid that is discharged from the stationary energy storage unit is subtracted from the amount of power originating from the grid that is stored in the stationary energy storage unit. Based on the amount of electricity originating from the power generation device stored in the stationary energy storage unit, the amount of electricity originating from the grid stored in the stationary energy storage unit, the fifth power, the fourth power, the second power, and the first power, the ratio of the first power originating from the power generation device is calculated. The AC power is multiplied by the ratio derived from the power generation device to calculate the power originating from the power generation device that is output to the distribution board. Power conversion system.

8. A third DC / DC converter connected between the onboard energy storage unit and the confluence point, A sixth DC power meter is installed between the aforementioned junction and the third DC / DC converter, The system further comprises a seventh DC power meter installed between the third DC / DC converter and the on-board power storage unit, The control unit measures the amount of electricity originating from the power generation device that is output to the distribution board, based on the AC power, the first to fifth powers, and the sixth to seventh powers measured by the sixth to seventh DC power meters, respectively. The power conversion system according to claim 7.

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