Power receiving and transforming system

Abstract

To realize a power receiving and transforming system in which an AC system and a DC system can coexist.SOLUTION: In the first control device (26) included in the power reception and transformation system, the first command value which is a command value related to the active power is calculated by adding the command value calculated by the DC bus voltage control unit (263) based on the DC bus voltage to the command value calculated by the first AC system control unit (261) based on the active power at the power receiving point.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power receiving and transforming system. [Background technology]

[0002] Patent Document 1 discloses a power receiving and transforming system including an AC-DC converter and a DC-DC converter. In the power receiving and transforming system, the AC-DC converter includes an AC-DC converter main circuit unit connected to an AC system and a DC system, and an AC-DC converter control unit that controls the AC-DC converter main circuit unit. The AC-DC converter control unit includes a first DC voltage control unit that controls the DC voltage of the DC system. The DC-DC converter also includes a DC-DC converter main circuit unit connected to the DC system and a power generation and storage source, and a DC-DC converter control unit that controls the DC-DC converter main circuit unit. The DC-DC converter control unit includes a second DC voltage control unit that controls the DC voltage of the DC system. The first DC voltage control unit and the second DC voltage control unit control the DC voltage of the DC system in different periods. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication WO2021 / 090371 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the power receiving and transforming system disclosed in Patent Document 1 is premised on connecting all loads and power generating sources to a DC bus, which means that an AC system that supplies AC power to AC loads and a DC system that supplies DC power to DC loads cannot coexist.

[0005] An object of one aspect of the present disclosure is to realize a power receiving and transforming system that allows AC systems and DC systems to coexist. [Means for solving the problem]

[0006] In order to solve the above-described problems, a power receiving and transforming system according to one aspect of the present disclosure is a power receiving and transforming system including an AC bus connected to an AC system and a DC power distribution system capable of supplying and receiving power to and from the AC bus, wherein the DC power distribution system includes a bidirectional AC-DC converter connected to the AC bus, a DC bus connected to the bidirectional AC-DC converter, a DC-DC converter connected to the DC bus, an energy storage device that charges from and discharges to the DC bus via the DC-DC converter, a first control device that controls the bidirectional AC-DC converter, and a second control device that detects a DC bus voltage of the DC bus and controls the DC-DC converter, and the first control device is configured to detect a first command value that is a command value related to active power and a second command value that is a command value related to reactive power. a first AC system control unit that detects active power at a power receiving point from the AC system and calculates a command value related to the active power of the bidirectional AC-DC converter based on the detected active power; a second AC system control unit that detects reactive power at the power receiving point and calculates the second command value based on the detected reactive power; and a DC bus voltage control unit that detects the DC bus voltage of the DC bus and calculates the command value related to the active power of the bidirectional AC-DC converter based on the detected DC bus voltage, wherein the first command value is calculated by adding the command value calculated by the first AC system control unit to the command value calculated by the DC bus voltage control unit. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to realize a power receiving and transforming system that allows AC systems and DC systems to coexist. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a power receiving and transforming system according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a first control device. [Figure 3] 10 is a graph illustrating a relationship between a DC bus voltage and a DC power command value in the output power of an AC-DC converter. [Figure 4] FIG. 2 is a diagram illustrating the configuration of a second control device. [Figure 5] 2 is a diagram illustrating an example of a configuration of the power receiving and transforming system according to the first embodiment, which is different from the configuration illustrated in FIG. 1. FIG. [Figure 6] 6 is a graph showing an example of an experiment for one day regarding fluctuations in power and voltage fluctuations in the power receiving and transforming system illustrated in FIG. 5. [Figure 7] 10 is a graph showing an example of an experiment for one day regarding fluctuations in power and voltage fluctuations in a power receiving and transforming system of a comparative example. [Figure 8] FIG. 10 is a diagram illustrating the configuration of a main part of a power receiving and transforming system according to a second embodiment. [Figure 9] 10 is a flowchart showing an example of control by a third control device. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a main part of a power receiving and transforming system according to a third embodiment. [Figure 11] 10 is a flowchart showing an example of control by a fourth control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment 1] An embodiment of the present disclosure will be described in detail below.

[0010] (Configuration of power receiving and transforming system) 1 is a diagram illustrating an example of the configuration of a power receiving and transforming system 1 according to embodiment 1. The power receiving and transforming system 1 is a system that receives AC power supplied from an AC system 100, either as AC power or after converting it into DC power and supplies it to a load. As shown in FIG. 1, the power receiving and transforming system 1 includes an AC bus 10, an AC load 15, and a DC power distribution system 20.

[0011] The AC bus 10 is a bus connected to the AC system 100. The AC load 15 is a load that consumes AC power supplied via the AC bus 10. The AC load 15 is, for example, a device such as a motor that operates on AC power.

[0012] The DC power distribution system 20 is a system capable of supplying and receiving power to and from the AC bus 10. The DC power distribution system 20 includes an AC-DC converter 21, a DC bus 22, a power storage device 23, a DC-DC converter 24, a DC load 25, a first control device 26, and a second control device 27.

[0013] The AC-DC converter 21 is connected to the AC bus 10. The AC-DC converter 21 is a so-called bidirectional AC-DC converter. The DC bus 22 is a bus connected to the AC-DC converter 21.

[0014] The power storage device 23 stores electric power as energy internally and supplies the stored energy as direct current to the DC bus 22 as needed. The power storage device 23 may be a device equipped with a secondary battery such as a lithium ion battery, a sodium-sulfur (NaS) battery, a redox flow battery, or a lead-acid battery. However, the power storage device 23 is not limited to a device equipped with a secondary battery. Any unit having a function of storing electric energy can be used as the power storage device 23, such as a capacitor, a superconducting power storage unit, a flywheel-type power storage unit, or a compressed air-type power storage unit.

[0015] The DC-DC converter 24 is a power conversion device that converts the voltage of DC power supplied from the power storage device 23 and discharges the power to the DC bus 22. The DC-DC converter 24 also converts the voltage of DC power supplied from the DC bus 22 and charges the power storage device 23. In other words, the power storage device 23 is charged and discharged between the power storage device 23 and the DC bus 22 via the DC-DC converter 24.

[0016] The DC load 25 is a load connected to the DC bus 22. The DC load 25 consumes DC power supplied via the DC bus 22. The DC load 25 is, for example, a device such as a robot arm that operates on DC power.

[0017] 1 shows the minimum configuration of a power receiving and transforming system 1. The power receiving and transforming system 1 may include a plurality of AC loads 15, and may further include an AC power generating source. Furthermore, the DC power distribution system 20 may include a plurality of power storage devices 23, DC-DC converters 24, and / or DC loads 25, and may further include a DC power generating source such as a solar panel.

[0018] (First control device) 2 is a diagram illustrating an example of the configuration of the first control device 26. The first control device 26 is a control device that controls the AC-DC converter 21. As shown in FIG. 2, the first control device 26 includes a first AC system control unit 261, a second AC system control unit 262, a DC bus voltage control unit 263, an adder unit 264, and an output control unit 265.

[0019] The first AC system control unit 261 detects the active power at the receiving point 11 of the AC power from the AC system 100, and calculates a command value for the active power of the AC-DC converter 21 based on the detected active power. Specifically, the first AC system control unit 261 calculates the active power command value Pa_ac. When Pa_ac is a positive value, it indicates that power is supplied from the AC bus 10 side to the DC bus 22 side, and when it is a negative value, it indicates that power is supplied from the DC bus 22 side to the AC bus 10 side. The first AC system control unit 261 includes an addition / subtraction unit 261a and a command value determination unit 261b.

[0020] The addition / subtraction unit 261a subtracts the output value Pa1 of the active power in the input / output AC power of the AC-DC converter 21 from the detected value Pm of the active power at the power reception point 11, and further adds the command value Pa_dc regarding the active power of the AC-DC converter 21. When Pm, Pa1, and Pa_dc are all positive values, it indicates that power is being supplied from the AC bus 10 side to the DC bus 22 side, and when they are negative values, it indicates that power is being supplied from the DC bus 22 side to the AC bus 10 side. Let the output of the addition / subtraction unit 261a be u.

[0021] The command value determination unit 261b determines Pa_ac as follows based on the magnitude relationship between the upper limit Po and the lower limit Pu of the active power at the power reception point 11 and the output u of the addition / subtraction unit 261a. Note that Po is determined by a contract with the utility company or the like regarding the power supplied from the AC system 100. Also, Pu is determined by restrictions on reverse power flow to the AC system 100 or the like. · When u > Po, set Pa_ac = Po - u. · When Po ≥ u ≥ Pu, set Pa_ac = 0. · When u < Pu, set Pa_ac = Pu - u.

[0022] The DC bus voltage control unit 263 detects the DC bus voltage Vma of the DC bus 22 and calculates the command value Pa_dc regarding the active power of the AC-DC converter 21 based on the detected Vma.

[0023] Figure 3 is a graph illustrating the relationship between Vma and Pa_dc. In the example shown in Figure 3, for Vma, the first threshold value Vua2, the second threshold value Vua1, the third threshold value Voa1, and the fourth threshold value Voa2 are set such that Vua2 < Vua1 < Voa1 < Voa2. Also, for Pa_dc, a lower limit value -Pa_dc_L and an upper limit value +Pa_dc_L are set.

[0024] Regarding the DC bus voltage, the range greater than Vua1 and less than Voa1 is referred to as the first range. Pa_dc is a command value regarding the active power of the AC-DC converter 21 that causes the DC bus voltage to return within the first range when it deviates from the first range. The DC bus voltage control unit 263 calculates Pa_dc as follows according to the magnitude relationships among Vua2, Vua1, Voa1, and Vma and Voa2. · When Vma < Vua2, the DC bus voltage control unit 263 sets the value of Pa_dc to +Pa_dc_L. · When Vua2 ≤ Vma ≤ Vua1, the DC bus voltage control unit 263 determines the value of Pa_dc by a linear function that becomes +Pa_dc_L when Vma = Vua2 and becomes 0 when Vma = Vua1. · When Vua1 < Vma < Voa1, the DC bus voltage control unit 263 sets the value of Pa_dc to 0. · When Voa1 ≤ Vma ≤ Voa2, the DC bus voltage control unit 263 determines the value of Pa_dc by a linear function that becomes 0 when Vma = Voa1 and becomes -Pa_dc_L when Vma = Voa2. · When Vma > Voa2, the DC bus voltage control unit 263 sets the value of Pa_dc to -Pa_dc_L.

[0025] The adder 264 calculates a first command value Pa2 regarding the active power in the input / output AC power of the AC-DC converter 21. Pa2 is calculated by adding Pa_dc calculated by the DC bus voltage control unit 263 to Pa_ac calculated by the first AC system control unit 261.

[0026] The second AC system control unit 262 detects the reactive power at the power receiving point 11 and calculates a second command value Qa2 regarding the reactive power in the input / output AC power of the AC-DC converter 21 based on the detected reactive power. Specifically, the second AC system control unit 262 calculates Qa2 according to the following formula (1). [[ID=二十]] [[ID=二十一]]

Equation

[0027] The output control unit 265 drives the AC-DC converter 21 so that the input / output AC power is adjusted according to Pa2 and Qa2. Specifically, the output control unit 265 generates a control signal for the AC-DC converter 21 according to Pa2 and Qa2, and outputs the control signal to the AC-DC converter 21. Thereby, the first control device 26 controls the active power of the AC power input / output by the AC-DC converter 21 to Pa2 and the reactive power to Qa2.

[0028] (Second Control Device) FIG. 4 is a diagram illustrating the configuration of the second control device 27. The second control device 27 detects the DC bus voltage Vmb in the DC bus 22 and controls the DC-DC converter 24. In other words, the second control device 27 controls the charge / discharge of the power storage device 23. As shown in FIG. 4, the second control device 27 includes a command value determination unit 271 and a DC-DC converter output control unit 272.

[0029] The command value determination unit 271 detects Vmb and determines the command value Pb for the charge / discharge power of the power storage device 23. In this specification, for Pb, when it is positive, it is the command value for the charging power to the power storage device 23, and when it is negative, it is the command value for the discharging power from the power storage device 23. Vmb is the value of the DC bus voltage detected in the second control device 27. Therefore, Vmb does not necessarily match Vma, which is the value of the DC bus voltage detected in the first control device 26.

[0030] FIG. 4 also shows a graph exemplifying the relationship between Vmb and Pb. In the example shown in FIG. 4, for Vmb, the fifth threshold value Vub2, the sixth threshold value Vub1, the seventh threshold value Vob1, and the eighth threshold value Vob2 are set such that Vub2 < Vub1 ≦ Vua2 < Vua1 < Voa1 < Voa2 ≦ Vob1 < Vob2. Also, for Pb, a lower limit value -Pb_L and an upper limit value +Pb_L are set.

[0031] Regarding the DC bus voltage, the range of Vub1 or more and Vob1 or less is referred to as the second range. The second range includes the first range. The command value determination unit 271 determines Pb so as to return the DC bus voltage back into the second range when it deviates from the second range. That is, the second control device 27 controls the DC-DC converter 24 with the goal of returning the DC bus voltage back into the second range when it deviates from the second range. Specifically, the command value determination unit 271 determines Pb as follows according to the magnitude relationship between Vub2, Vub1, Vob1, Vob2, and Vmb. · When Vmb < Vub2, the command value determination unit 271 sets the value of Pb to -Pb_L. · When Vub2 ≦ Vmb ≦ Vub1, the command value determination unit 271 determines the value of Pb by a linear function that becomes -Pb_L when Vmb is Vub2 and becomes 0 when Vmb is Vub1. · When Vub1 < Vmb < Vob1, the command value determination unit 271 sets the value of Pb to 0. If Vob1≦Vmb≦Vob2, the command value determination unit 271 determines the value of Pb using a linear function that is 0 when Vmb is Vob1 and is +Pb_L when Vmb is Vob2. If Vmb>Vob2, the command value determination unit 271 sets the value of Pb to +Pb_L.

[0032] The DC-DC converter output control section 272 generates a control signal for the DC-DC converter 24 according to Pb, and outputs the control signal to the DC-DC converter 24. As a result, the second control device 27 controls the charging / discharging power of the power storage device 23 to Pb.

[0033] (Experimental example) Fig. 5 is a diagram illustrating the configuration of a power receiving and transformation system 1A that is different from the power receiving and transformation system 1. As shown in Fig. 5, the power receiving and transformation system 1A includes a DC power distribution system 20A instead of the DC power distribution system 20, and further includes an AC power generating source 16. The AC power generating source 16 is a power source included in the power receiving and transformation system 1A that is different from the AC system 100 and that supplies AC power to the AC bus 10. In addition to the configuration of the DC power distribution system 20, the DC power distribution system 20A includes a DC power generating source 23A, a DC-DC converter 24A, a DC load 25A, a power storage device 23B, and a DC-DC converter 24B.

[0034] The DC power generating source 23A is connected to the DC bus 22. The DC power generating source 23A generates DC power. The DC power generating source 23A is, for example, a solar panel. The DC-DC converter 24A is a power conversion device that converts the voltage of the DC power generated by the DC power generating source 23A and discharges it to the DC bus 22.

[0035] The DC load 25A consumes DC power supplied via the DC bus 22. The DC load 25 is, for example, a charger that charges an electric vehicle.

[0036] Like the power storage device 23, the power storage device 23B stores electric power as energy therein and supplies the stored energy as direct current to the DC bus 22 as needed. The specific structure of the power storage device 23B may be the same as or different from that of the power storage device 23. The DC-DC converter 24B is a power conversion device that converts the voltage of the DC power supplied from the power storage device 23B and discharges it to the DC bus 22. In addition, the DC-DC converter 24B converts the voltage of the DC power supplied from the DC bus 22 and charges the power storage device 23B.

[0037] 5, DC power distribution system 20A includes first control device 26 and second control device 27, similar to DC power distribution system 20. Specifically, DC power distribution system 20A includes first control device 26 corresponding to AC-DC converter 21, second control device 27 corresponding to DC-DC converter 24, second control device 27 corresponding to DC-DC converter 24A, and second control device 27 (not shown) corresponding to DC-DC converter 24B.

[0038] Fig. 6 is a graph showing an example of a one-day experiment on fluctuations in power and voltage in the power receiving and transforming system 1A. Fig. 7 is a graph showing an example of a one-day experiment on fluctuations in power and voltage in the power receiving and transforming system of the comparative example.

[0039] The power receiving and transforming system of the comparative example differs from the power receiving and transforming system 1A in that, among the processes in the first control device 26, the processing in the DC bus voltage control unit 263 is omitted. In other words, in the power receiving and transforming system of the comparative example, the first command value Pa2 is not based on the DC bus voltage Vma. In further other words, in the power receiving and transforming system of the comparative example, the active power command value Pa_ac calculated based on the active power at the power receiving point 11 becomes the first command value Pa2 as is.

[0040] Reference numeral 601 in Fig. 6 and reference numeral 701 in Fig. 7 are graphs showing active power. In these graphs, the black line indicates the active power at the power receiving point 11. The dark gray line indicates the active power in the power consumption of the AC load 15. The light gray line indicates the active power in the input / output AC power of the AC-DC converter 21. The horizontal axis indicates time (h), and the vertical axis indicates active power (kW). For active power, the power supplied to the DC bus 22 is taken as a positive value.

[0041] Reference numeral 602 in Fig. 6 and reference numeral 702 in Fig. 7 are graphs showing reactive power. In these graphs, the black line indicates the reactive power at the power receiving point 11. The dark gray line indicates the reactive power in the power consumption of the AC load 15. The light gray line indicates the reactive power in the input / output AC power of the AC-DC converter 21. The horizontal axis indicates time (h), and the vertical axis indicates reactive power (kVar). Reactive power is shown as a positive value when lagging reactive power is consumed.

[0042] Reference numeral 603 in Fig. 6 and reference numeral 703 in Fig. 7 are graphs showing the charge / discharge power in the power storage devices 23, 23B. In these graphs, the black line indicates the charge / discharge power in the power storage device 23. The gray line indicates the charge / discharge power in the power storage device 23B. The horizontal axis indicates time (h) and the vertical axis indicates power (kW). With respect to power, charging power is taken as a positive value.

[0043] Graphs showing Vma are indicated by reference numerals 604 in Fig. 6 and 704 in Fig. 7. In these graphs, the horizontal axis represents time (h) and the vertical axis represents DC voltage (V).

[0044] In the diagrams 601 and 701, the power levels of 0 kW and 1000 kW are indicated by dashed lines, respectively. In the experimental examples shown in Fig. 6 and Fig. 7, PF = 1, Po = 1000 kW, and Pu = 0 kW. Therefore, in both the power receiving and transforming system 1A and the comparative power receiving and transforming system, the active power at the power receiving point 11 was controlled to be equal to or greater than 0 kW and equal to or less than 1000 kW.

[0045] As described above, in the power receiving and transforming system of the comparative example, the processing in the DC bus voltage control unit 263 of the first control device 26 was omitted. Therefore, in the power receiving and transforming system of the comparative example, as shown by the reference numeral 704, the second control device 27 controlled the DC-DC converter 24 so that the DC bus voltage Vma was in the range of not less than Vua2 and not more than Voa2.

[0046] Meanwhile, in the power receiving and transforming system 1A, processing was executed in the DC bus voltage control unit 263 of the first control device 26. Therefore, in the power receiving and transforming system 1A, as indicated by the reference numeral 604, the first control device 26 controlled the AC-DC converter 21 so that the DC bus voltage Vma was in the range of not less than Vua2 and not more than Voa2.

[0047] Because first control device 26 controlled AC-DC converter 21 as described above, the capacity required for power storage devices 23, 23B in power receiving and transformation system 1A was smaller than the capacity required for power storage devices 23, 23B in the power receiving and transformation system of the comparative example. Comparing reference numerals 603 and 703, the charge and discharge power of power storage devices 23, 23B was smaller in power receiving and transformation system 1A than in the power receiving and transformation system of the comparative example. In particular, as shown by reference numeral 603, in power receiving and transformation system 1A, charging to power storage devices 23, 23B was not performed, and only discharging was performed.

[0048] Specifically, in the power receiving and transforming system of the comparative example shown in Fig. 7, a capacity of 5553 kWh was required for power storage device 23 and 3784 kWh was required for power storage device 23B, for a total of 9337 kWh. On the other hand, in the power receiving and transforming system 1 shown in Fig. 6, a capacity of 4635 kWh was required for power storage device 23 and 2390 kWh was required for power storage device 23B, for a total of 7025 kWh. Compared to the power receiving and transforming system of the comparative example, power receiving and transforming system 1 was able to reduce the total capacity of power storage devices 23, 23B by 2312 kWh (i.e., approximately 25% of the total capacity of power storage devices 23, 23B in the power receiving and transforming system of the comparative example).

[0049] (effect) As described above, in the power receiving and transforming system 1, the first control device 26 controls the active power of the input and output AC power of the AC-DC converter 21 so as to control the voltages of both the AC bus 10 and the DC bus 22. Furthermore, the second control device 27 controls the charging and discharging of the power storage device 23 so as to control the DC voltage of the DC bus 22. This makes it possible for the power receiving and transforming system 1 to have both an AC system that supplies AC power to the AC load 15 and a DC system that supplies DC power to the DC load 25.

[0050] In particular, in the power receiving and transforming system 1, the DC voltage of the DC bus 22 can be automatically switched between control by the AC-DC converter 21 and control by the DC-DC converter 24 in accordance with the DC voltage of the DC bus 22. Furthermore, the reduction in the capacity required for the power storage device 23 reduces the overall cost of the power receiving and transforming system 1.

[0051] Furthermore, any number of power storage systems can be installed at any location within DC power distribution system 20. The power storage system here refers to a system including a power storage device, a DC-DC converter, and a control device similar to second control device 27. Therefore, in power receiving and transforming system 1, it is possible to utilize multiple power storage systems, and multiple power storage systems located remotely from each other.

[0052] 1 are functional blocks that execute information processing. Therefore, any physical hardware configuration is acceptable as long as the functions of the first control device 26 and the second control device 27 described above are provided. The first control device 26 and the second control device 27 may be configured as separate devices or as a single device.

[0053] [Embodiment 2] Other embodiments of the present disclosure will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0054] Fig. 8 is a diagram illustrating the configuration of a main part of a power receiving and transforming system 2 according to embodiment 2. Fig. 8 shows only a DC load 25 and its vicinity provided in the power receiving and transforming system 2. As shown in Fig. 8, the power receiving and transforming system 2 includes a third control device 28 in addition to the configuration of the power receiving and transforming system 1A.

[0055] The third control device 28 controls the operation of the DC load 25 in accordance with the DC bus voltage Vmc on the DC bus 22. Specifically, a ninth threshold VL is set for Vmc, which is a threshold at which power consumption in the DC load 25 should be reduced or the operation of the DC load 25 should be stopped. When Vmc is equal to or lower than VL, the third control device 28 reduces power consumption in the DC load 25 or stops the operation of the DC load 25. Vmc is the value of the DC bus voltage detected by the third control device 28. Therefore, Vmc does not necessarily match Vma, which is the value of the DC bus voltage detected by the first control device 26, or Vmb, which is the value of the DC bus voltage detected by the second control device 27.

[0056] 9 is a flowchart showing an example of control by the third control device 28. The third control device 28 detects Vmc (S11) and determines whether Vmc≦VL (S12). If Vmc≦VL (YES in S12), the third control device 28 reduces the power consumption of the DC load 25 or stops the operation of the DC load 25 (S13). If Vmc≦VL is not satisfied (NO in S12), the third control device 28 continues the operation of the DC load 25 (S14). After step S13 or step S14, the third control device 28 repeats the process from step S11. Note that if step S12 is NO after step S13, the third control device 28 returns the power consumption of the DC load 25 to a normal value in step S14.

[0057] In the power receiving and transforming system 2, the third control device 28 controls the operation of the DC load 25 as described above, so that the DC voltage on the DC bus 22 becomes more stable.

[0058] In particular, when VL is set to be equal to or lower than Vua2, the power consumption of the DC load 25 is supplied from the DC power generating source 23A, and the shortage of power consumption is supplied from the AC bus 10. In this case, only when the value of Pa_ac calculated by the first AC system control unit 261 is not 0, the third control device 28 suppresses the power consumption of the DC load 25 or stops the operation of the DC load 25.

[0059] Furthermore, when VL is set to be equal to or lower than Vub2, the power consumed by the DC load 25 is supplied from the DC power generating source 23A, and the shortage of power consumption is supplied from the AC bus 10. In this case, when the value of Pa_ac is not 0, the power storage devices 23, 23B discharge the shortage of power. Only when the power storage devices 23, 23B cannot discharge, the third control device 28 suppresses the power consumption of the DC load 25 or stops the operation of the DC load 25.

[0060] [Embodiment 3] Further embodiments of the present disclosure are described below.

[0061] Fig. 10 is a diagram illustrating the configuration of the main parts of a power receiving and transforming system 3 according to embodiment 3. Fig. 10 shows only a DC power generating source 23A and its vicinity provided in the power receiving and transforming system 3. As shown in Fig. 10, the power receiving and transforming system 3 includes a fourth control device 29 in addition to the configuration of the power receiving and transforming system 1A.

[0062] The fourth control device 29 controls the amount of power generated by the DC power generating source 23A in accordance with the DC bus voltage Vmd on the DC bus 22. Specifically, a tenth threshold VH is set for Vmd, which is a threshold at which the amount of power generated by the DC power generating source 23A should be suppressed. When Vmd is equal to or greater than VH, the fourth control device 29 controls the DC-DC converter 24A so that the amount of power generated by the DC power generating source 23A is suppressed. Vmd is the value of the DC bus voltage detected by the fourth control device 29. For this reason, Vmd does not necessarily match Vma, which is the value of the DC bus voltage detected by the first control device 26, Vmb, which is the value of the DC bus voltage detected by the second control device 27, or Vmc, which is the value of the DC bus voltage detected by the third control device 28.

[0063] 11 is a flowchart showing an example of control by the fourth control device 29. The fourth control device 29 detects Vmd (S21) and determines whether Vmd≧VH (S22). If Vmd≧VH (YES in S22), the fourth control device 29 reduces or stops power generation in the DC power generating source 23A (S23). If Vmd≧VH is not true (NO in S22), the fourth control device 29 continues power generation in the DC power generating source 23A (S24). After step S23 or step S24, the fourth control device 29 repeats the process from step S21. Note that if step S22 is NO after step S23, the fourth control device 29 resumes power generation in the DC power generating source 23A in step S24.

[0064] In the power receiving and transforming system 3, the fourth control device 29 controls the power generation in the DC power generating source 23A as described above, so that the DC voltage in the DC bus 22 becomes more stable.

[0065] In particular, when VH is set to Voa2 or more, the power generated by the DC power generating source 23A is supplied to the DC load 25, and the surplus power is supplied to the AC bus 10. In this case, only when the value of Pa_ac calculated by the first AC system control unit 261 is not 0, the fourth control device 29 suppresses or stops power generation in the DC power generating source 23A.

[0066] Furthermore, when VH is set to be equal to or greater than Vob2, the power generated by the DC power generating source 23A is supplied to the DC load 25, and the surplus power is supplied to the AC bus 10. In this case, when the value of Pa_ac is not 0, the surplus power is charged to the power storage devices 23, 23B. Only when the power storage devices 23, 23B cannot be charged, does the fourth control device 29 reduce or stop power generation in the DC power generating source 23A.

[0067] [Software implementation example] The functions of the first control device 26, the second control device 27, the third control device 28, and the fourth control device 29 (hereinafter referred to as "devices") can be realized by a program that causes a computer to function as the devices, and a program that causes a computer to function as each control block of the devices.

[0068] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0069] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0070] In addition, some or all of the functions of each of the control blocks can be realized by logic circuits. For example, integrated circuits in which logic circuits that function as each of the control blocks are formed are also included in the scope of the present disclosure. In addition, the functions of each of the control blocks can also be realized by, for example, a quantum computer.

[0071] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0072] 〔summary〕 The present disclosure can also be expressed as follows:

[0073] A power receiving and transforming system according to a first aspect of the present disclosure is a power receiving and transforming system including an AC bus connected to an AC system and a DC power distribution system capable of supplying and receiving power to and from the AC bus, wherein the DC power distribution system includes a bidirectional AC-DC converter connected to the AC bus, a DC bus connected to the bidirectional AC-DC converter, a DC-DC converter connected to the DC bus, a power storage device that charges from and discharges to the DC bus via the DC-DC converter, a first control device that controls the bidirectional AC-DC converter, and a second control device that detects a DC bus voltage of the DC bus and controls the DC-DC converter, and the first control device is configured to detect a first command value that is a command value related to active power and a second command value that is a command value related to reactive power. a first AC system control unit that detects active power at a power receiving point from the AC system and calculates a command value related to the active power of the bidirectional AC-DC converter based on the detected active power; a second AC system control unit that detects reactive power at the power receiving point and calculates the second command value based on the detected reactive power; and a DC bus voltage control unit that detects the DC bus voltage of the DC bus and calculates a command value related to the active power of the bidirectional AC-DC converter based on the detected DC bus voltage, wherein the first command value is calculated by adding the command value calculated by the first AC system control unit to the command value calculated by the DC bus voltage control unit.

[0074] In the power receiving and converting system according to Embodiment 2 of the present disclosure, in Embodiment 1, the first AC system control unit subtracts the output value of the active power in the output power of the bidirectional AC-DC converter from the detected value of the active power at the power receiving point, and further, based on the addition / subtraction unit regarding the active power of the bidirectional AC-DC converter output by the DC bus voltage control unit, the upper limit and lower limit of the active power at the power receiving point, and the magnitude relationship between the output of the addition / subtraction unit, a command value determination unit that calculates a command value of the active power is provided.

[0075] The power receiving and converting system according to Embodiment 3 of the present disclosure, in Embodiment 1 or 2, the second AC system control unit calculates a command value of the reactive power in the output power of the bidirectional AC-DC converter according to the following formula (1), the power receiving and converting system according to claim 1.

Number

[0076] A power receiving and transforming system according to a fifth aspect of the present disclosure, in any one of aspects 1 to 4, further includes a DC load connected to the DC bus and a third control device that controls operation of the DC load in accordance with a DC bus voltage on the DC bus, and the third control device reduces power consumption in the DC load or stops operation of the DC load when the DC bus voltage is equal to or lower than a ninth threshold that is a threshold at which power consumption in the DC load should be reduced or operation of the DC load should be stopped.

[0077] A power receiving and transforming system according to a sixth aspect of the present disclosure is any one of the first to fifth aspects, further comprising: a DC power generating source connected to the DC bus; and a fourth control device that controls the amount of power generated in the DC power generating source according to the DC bus voltage in the DC bus, wherein the fourth control device controls the DC-DC converter so that the amount of power generated in the DC power generating source is suppressed when the DC bus voltage is equal to or greater than a tenth threshold, which is a threshold at which the amount of power generated in the DC power generating source should be suppressed.

[0078] A power receiving and transforming system according to a seventh aspect of the present disclosure is in any one of the first to sixth aspects, wherein the first control device and the second control device constitute a single higher-level device.

[0079] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0080] 1, 1A, 2, 3 Power receiving and transforming system 10 AC bus 11 Power receiving point 20, 20A DC power distribution system 21 AC-DC converter (bidirectional AC-DC converter) 22 DC bus 23, 23B Power storage device 23A DC power source 24, 24A, 24B DC-DC Converters 25, 25A DC load 26 First control device 261 First AC system control section 261a Addition / subtraction section 261b Command value determination unit 262 Second AC system control section 263 DC bus voltage control section 265 Output control section 27 Second control device 28 Third control device 29 Fourth control device

Claims

1. an AC bus connected to the AC system; a DC power distribution system capable of supplying and receiving power to and from the AC bus, The DC power distribution system includes: a bidirectional AC-DC converter connected to the AC bus; a DC bus connected to the bidirectional AC-DC converter; a DC-DC converter connected to the DC bus; a power storage device that is charged from the DC bus and discharged to the DC bus via the DC-DC converter; a first control device that controls the bidirectional AC-DC converter; a second control device that detects a DC bus voltage of the DC bus and controls the DC-DC converter; The first control device an output control unit that drives the bidirectional AC-DC converter so that input and output AC power is adjusted in accordance with a first command value that is a command value related to active power and a second command value related to reactive power; a first AC system control unit that detects active power at a power receiving point from the AC system and calculates a command value related to the active power of the bidirectional AC-DC converter based on the detected active power; a second AC system control unit that detects reactive power at the power receiving point and calculates the second command value based on the detected reactive power; a DC bus voltage control unit that detects the DC bus voltage of the DC bus and calculates a command value related to active power of the bidirectional AC-DC converter based on the detected DC bus voltage, a power receiving and transforming system, wherein the first command value is calculated by adding a command value calculated by the DC bus voltage control unit to a command value calculated by the first AC system control unit.

2. The first AC system control unit an adding / subtracting unit that subtracts an output value of active power in the output power of the bidirectional AC-DC converter from a detected value of active power at the power receiving point, and adds a command value related to the active power of the bidirectional AC-DC converter output by the DC bus voltage control unit; 2. The power receiving and transforming system according to claim 1, further comprising: a command value determination unit that calculates a command value for active power based on a magnitude relationship between an upper limit and a lower limit of active power at the power receiving point and an output of the adding and subtracting unit.

3. 2. The power receiving and transforming system according to claim 1, wherein the second AC system control unit calculates a command value of reactive power in the output power of the bidirectional AC-DC converter by the following equation (1): [Equation 1] PF: command value of power factor control at the power receiving point (any value in the range of 0<PF≦1) PF±: Positive or negative power factor command value (either +1 (lag) or -1 (lead)) Pm: Detected value of active power at the receiving point Qm: Detected value of reactive power at the receiving point Qa1: Output value of reactive power in the input / output AC power of the bidirectional AC-DC converter

4. the DC bus voltage control unit calculates a command value for active power of the bidirectional AC-DC converter, which causes the DC bus voltage to return to within a first range when the DC bus voltage deviates from the first range; 2. The power receiving and transforming system of claim 1, wherein the second control device controls the DC-DC converter with the goal of restoring the DC bus voltage to within a second range that includes the first range when the DC bus voltage deviates from the second range.

5. a DC load connected to the DC bus; a third control device that controls operation of the DC load in response to a DC bus voltage on the DC bus; The power receiving and transforming system of claim 1, wherein the third control device reduces power consumption in the DC load or stops operation of the DC load when the DC bus voltage is equal to or lower than a ninth threshold, which is a threshold at which power consumption in the DC load should be reduced or operation of the DC load should be stopped.

6. a DC power generating source connected to the DC bus; a fourth control device that controls the amount of power generated by the DC power generating source in accordance with a DC bus voltage of the DC bus, 2. The power receiving and transforming system according to claim 1, wherein the fourth control device controls the DC-DC converter so that the amount of power generated at the DC power generating source is suppressed when the DC bus voltage is equal to or greater than a tenth threshold that is a threshold at which the amount of power generated at the DC power generating source should be suppressed.

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