Load control device and DC power distribution system

Abstract

To provide a load control device that suppresses a voltage rise on a DC bus even if a plurality of loads simultaneously generate regenerative power.SOLUTION: A DC power distribution system includes a DC bus, a plurality of regenerative loads connected to the DC bus, a storage battery connected to the DC bus via a DC / DC converter, and a load control device that performs regeneration control of the loads. The load control device includes a storage unit that stores regenerative power data of the loads and a preset upper limit charge power when charging the storage battery, and a control unit that controls the regeneration start time of each of the plurality of loads so that the upper limit charge power is not exceeded during the regenerative operation of the plurality of loads.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a load control device and a DC power distribution system.

Background Art

[0002] In recent years, the introduction of renewable energy such as solar power generation and wind power generation, and storage batteries has been progressing, and a DC power distribution system that can efficiently utilize them has attracted attention. In a conventional AC system, the regenerative power generated when a load such as a motor stops is consumed as heat by a braking resistor or the like. This is because it is difficult to regenerate the regenerative power into the power system, such as synchronizing it, in the AC system. In a DC system, unlike an AC system, it is not necessary to synchronize the regenerative power from the load with the power distribution system, and it is possible to easily regenerate it into the DC system.

[0003] Therefore, in a DC power distribution system, a device that generates regenerative power as a load is often connected, and the generated regenerative power is utilized for charging a storage battery or the like (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although Patent Document 1 describes that power regeneration can be easily performed from each load, it does not describe how to specifically regenerate and utilize power from a plurality of loads. In a DC power distribution system using a storage battery, a DC / DC converter is used for charging and discharging the storage battery. The DC / DC converter has a rated power, and it is not possible to charge more power than that.

[0006] Therefore, when multiple loads are stopped simultaneously or when regenerative power is generated from many devices, if the total value of the regenerative power exceeds the rated power of the DC / DC converter for the storage battery, not all the power can be charged into the storage battery, the voltage of the DC bus rises, and there is a risk of damage to each load, converter, etc. connected to the DC bus, or overvoltage shutdown.

[0007] The present disclosure discloses a technology for solving the above problems, and an object thereof is to provide a load control device and a DC power distribution system capable of controlling a load so as to avoid a situation where regenerative power from the load cannot be charged into the storage battery and the voltage of the DC bus rises.

Means for Solving the Problems

[0008] The load control device according to the present disclosure is a load control device that performs control to regenerate the power of a plurality of loads connected to a DC bus to a storage battery connected to the DC bus, a storage unit that holds regenerative power data of the plurality of loads and a power value preset when charging the storage battery; and a control unit that controls the regenerative start times of the plurality of loads so as not to exceed the preset power value during the regenerative operation of the plurality of loads.

Effects of the Invention

[0009] According to the present disclosure, it is possible to provide a load control device and a DC power distribution system that can prevent the total value of regenerative power from exceeding a preset power value even when a plurality of loads regenerate simultaneously.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13A

Figure 13B

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the load control device and the DC power distribution system according to the present disclosure will be described with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts. Therefore, detailed descriptions thereof may be omitted to avoid duplication.

[0012] Embodiment 1. Hereinafter, the load control device and the DC power distribution system according to Embodiment 1 will be described with reference to the drawings. <Configuration of DC Power Distribution System> FIG. 1 is a schematic diagram showing the configuration of the DC power distribution system according to Embodiment 1. In FIG. 1, in the DC power distribution system 1, an AC commercial power source 21 as an AC power supply source is connected to a DC bus 3 via an AC / DC converter 24, and a storage battery 22 as a DC power source is connected via a DC / DC converter 25. Further, loads 23a, 23b, 23c are connected as loads capable of power regeneration. Note that a converter may be provided between the loads 23a, 23b, 23c and the DC bus 3. The loads 23a, 23b, 23c are respectively connected to the load control device 10 by communication lines 26a, 26b, 26c.

[0013] The AC / DC converter 24 is connected between the commercial power supply 21 and the DC bus 3, and converts the AC power supplied from the commercial power supply 21 into DC power. The target voltage of the DC bus 3 is set, and the output power is controlled so as to reach that voltage. Also, when the upper limit power of the AC / DC converter 24 is reached, even if it is less than the target voltage, it operates at the upper limit power.

[0014] The DC / DC converter 25 charges and discharges the storage battery 22. In this system, the DC / DC converter 25 charges the storage battery 22 so as to maintain the threshold voltage so that the DC bus voltage does not exceed the threshold value, and also charges the storage battery 22 so as not to exceed a preset power value. Here, the preset power is, for example, the rated power of the DC / DC converter 25, or may be a value equal to or less than the rated power. In the following description, the preset power will be referred to as the charging upper limit power. Also, the threshold voltage is set higher than the target voltage of the AC / DC converter 24 so as to charge when the loads 23a, 23b, 23c regenerate and the voltage of the DC bus 3 rises. When the regenerative power exceeds the charging upper limit power, the threshold voltage cannot be maintained, the DC bus voltage rises, and the DC / DC converter 25 stops due to overvoltage.

[0015] <Configuration of the load control device 10> The load control device 10 includes a storage unit 11, a control unit 12, a communication unit 13, and an operation unit 14. The storage unit 11 holds the charging upper limit power of the DC / DC converter 25 and the regenerative power data of each of the loads 23a, 23b, 23c. The regenerative power data is two-dimensional data having information on the regenerative time (s) required from the start to the end of regeneration of the load and the power (kW) at each time during regeneration. When there are a plurality of operations for outputting regenerative power to one load, the regenerative power data corresponding to each operation is held. The regenerative power data may be directly input by the user, or data may be received from each of the loads 23a, 23b, 23c by the communication unit 13. Also, data of approximate values indicating power greater than the actual regenerative power may be used.

[0016] The control unit 12 issues commands for the regeneration operation to each of the loads 23a, 23b, and 23c so that the total value of the regenerative power does not exceed the charging upper limit power of the DC / DC converter 25 for the storage battery 22. Details of the control of the regeneration operation by the control unit 12 will be described later.

[0017] The communication unit 13 communicates with each of the loads 23a, 23b, and 23c, and transmits commands such as the timing calculated by the control unit 12 and the regeneration operation mode including the possibility of regeneration to each of the loads 23a, 23b, and 23c. Further, the regenerative power data of each of the loads 23a, 23b, and 23c may be received. The communication means may be wired or wireless.

[0018] The operation unit 14 is a device for the user to input instructions for the regeneration operation such as stopping and decelerating the load device. For example, it has a device selection button, a stop button, etc., and can issue regeneration operation instructions to a plurality of load devices simultaneously. It may be a single button or the like that issues an instruction to stop a plurality of determined loads simultaneously. Further, it may be configured to be able to instruct startup and output fluctuations as well. Furthermore, not only local operations as described above but also having a higher-level system and being configured to be able to perform various instructions and settings through communication from the higher-level system may be possible.

[0019] <Operation of the load control device 10> FIG. 2A and FIG. 2B are flowcharts showing the operation of the load control device 10 according to Embodiment 1, and show a control flow for creating instructions for the regeneration operation to each load. Here, the charging upper limit power is a value held in the storage unit 11, and when there is no particular reason, the charging upper limit power of the DC / DC converter 25 for the storage battery 22 is input. The storage unit 11 receives input from, for example, the operation unit 14. First, in step S101, when a load to be stopped is selected, in step S102, the communication unit 13 transmits a stop instruction to the target load. Here, the selection of the load to be stopped and the stop instruction are executed by the operation unit 14.

[0020] The load control device 10 has a load list and a regeneration allowable list. In step S103, all the loads to be stopped are input to the load list, and nothing is input to the regeneration allowable list, leaving it in an empty state. That is, in step S101, the selected load will be input to the load list. Note that not only the type of load but also the stop priority may be assigned to the load list when there are multiple loads. Also, the maximum value (kW) of the regenerative power of the loads listed in the load list and the regeneration time (s) may be linked to the storage unit 11.

[0021] In step S104, it is determined whether there is a load in the load list whose maximum regenerative power exceeds the charging upper limit power of the DC / DC converter 25 for the storage battery 22. If there is no load whose maximum regenerative power exceeds the charging upper limit power of the DC / DC converter 25 for the storage battery 22 (No in step S104), the process proceeds to step S105. If there is a load whose maximum regenerative power exceeds the charging upper limit power of the DC / DC converter 25 (Yes in step S104), it is regarded as an error occurrence, the process proceeds to step S112, stored in the storage unit 11 as error information, and the process ends.

[0022] In step S104, if there is no load whose maximum regenerative power exceeds the charging upper limit power of the DC / DC converter 25, in step S105, one load is moved from the load list to the regeneration allowable list. Here, the order of movement is the stop priority, which may be determined in step S101 or may be "in the order of larger regenerative power", and any priority may be assigned.

[0023] In step S106, it is determined whether the total of the maximum regenerative powers of the loads in the regeneration allowable list is equal to or greater than the charging upper limit power. If it exceeds the charging upper limit power (Yes in step S106), the process proceeds to step S107. If it is below the charging upper limit power (No in step S106), the process proceeds to step S113.

[0024] In step S113, it is determined whether the load list is empty. If it is not empty (No in step S113), the process returns to step S105. If it is empty (Yes in step S113), the process proceeds to step S108.

[0025] In step S106, when the total maximum value of the regenerative power of the loads in the regeneration allowable list exceeds the charging upper limit power, since there are two or more loads in the regeneration allowable list, in step S107, one of the loads that was last moved to the regeneration allowable list is returned to the load list.

[0026] In step S108, regeneration is started for all the loads in the regeneration allowable list. In step S109, when all the loads in the regeneration allowable list have completed regeneration, the regenerative control is stopped. In step S110, the loads that have completed regeneration are deleted from the regeneration allowable list, and the regeneration allowable list is emptied.

[0027] In step S111, it is determined whether the load list is empty. If there are loads remaining in the load list (No in step S111), the process returns to step S105 and the regenerative operation is performed. If the load list is empty (Yes in step S111), the process ends.

[0028] As determined in step S104, if there is a load whose maximum regenerative power value exceeds the charging upper limit power when considered individually, the battery side cannot charge all the power. When constructing the system of the first embodiment, it is desirable to select loads so that the regenerative power of a single load does not exceed the charging upper limit power. If the regenerative power of a single load exceeds the charging upper limit power, as determined in step S104, the process ends.

[0029] The configurations of the DC power distribution system 1 and the load control device 10 according to the first embodiment are not limited to the above, and they may be composed of a part of them, or may have other demand facilities and power supply sources.

[0030] Hereinafter, an embodiment of the regeneration control will be described.

[0031] <Example 1> Loads to be stopped: Load 23a, Load 23b, Load 23c Load 23a: Maximum regeneration power 6 kW, regeneration time 8 s Load 23b: Maximum regeneration power 8 kW, regeneration time 6 s Load 23c: Maximum regeneration power 7 kW, regeneration time 7 s Charging upper limit power of the DC / DC converter 25 for the storage battery 22: 9 kW It is assumed that the conversion capacity of the AC / DC converter 24 is sufficiently large. Note that the regeneration power characteristics, which are the regeneration power data of each load, are shown in FIG. 3. Each load outputs a constant regeneration power during regeneration.

[0032] Hereinafter, the regeneration control procedure according to Example 1 will be described using the flowchart of FIG. 2 and the load list and regeneration permission list illustrated in FIGS. 4A and 4B. First, in step S101, Load 23a, Load 23b, and Load 23c are selected as the loads to be stopped by the operation unit 14. The stop priority order is Load 23a, Load 23b, Load 23c.

[0033] Next, in step S102, a stop instruction is transmitted to each load by the operation unit 14 via the communication unit 13.

[0034] In step S103, Load 23a, Load 23b, and Load 23c are input as the loads to be stopped in the load list, and nothing is input to the regeneration permission list, which is in an empty state. The load list and the regeneration permission list at this time are, for example, in the state of (a) in FIG. 4A.

[0035] In step S104, it is determined whether there is a load in the load list whose maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25 for the storage battery 22. Since the maximum value of the regenerative power of any load does not exceed the charging upper limit power of 9 kW of the DC / DC converter 25 (No in step S104), the process proceeds to step S105.

[0036] In step S105, the load 23a, which is the load with the highest stop priority in the load list, is moved to the regenerative power allowable list. The load list and the regenerative power allowable list at this time are in the state of (b) in FIG. 4A, for example.

[0037] In step S106, the only load in the regenerative power allowable list is the load 23a, and the maximum value of the regenerative power of the load 23a is 6 kW, which is less than or equal to the charging upper limit power of 9 kW of the DC / DC converter 25 (No in step S106), so the process proceeds to step S113. Although the notation in the total regenerative power column of the regenerative power allowable list is "6", it is noted as "6(≦9)" for the convenience of explanation as a notation compared with the charging upper limit power. The same applies hereinafter.

[0038] In step S113, it is determined whether the load list is empty. Since the loads 23b and 23c remain in the load list (No in step S113), the process returns to step S105.

[0039] In step S105, the load 23b, which is a load with a high stop priority in the load list, is moved to the regenerative power allowable list. The load list and the regenerative power allowable list at this time are in the state of (c) in FIG. 4A, for example. In step S106, the loads in the regenerative power allowable list are the load 23a and the load 23b, and the total of the maximum values of their regenerative powers is 14 kW, which exceeds the charging upper limit power of 9 kW of the DC / DC converter 25 (Yes in step S106), so the process proceeds to step S107. In step S107, the load 23b, which was the last to be moved to the regenerative power allowable list, is returned to the load list. The load list and the regenerative power allowable list at this time are in the state of (d) in FIG. 4A, for example.

[0040] Next, in step S108, regeneration of the load 23a in the regeneration allowable list is started. In step S109, when the regeneration of the load 23a in the regeneration allowable list is completed, in step S110, the load 23a for which regeneration has ended is deleted from the regeneration allowable list, and the regeneration allowable list is emptied.

[0041] Next, in step S111, the load list is checked, and since loads 23b and 23c remain (No in step S111), the process returns to step S105.

[0042] In step S105, the load 23b, which is the load with the highest stop priority in the load list, is moved to the regeneration allowable list. The load list and the regeneration allowable list at this time are in the state of (e) in FIG. 4B, for example.

[0043] In step S106, the load in the regeneration allowable list is only the moved load 23b, and the maximum value of the regeneration power of the load 23b is 8 kW, which is less than or equal to the charging upper limit power of 9 kW of the DC / DC converter 25 (No in step S106), so the process proceeds to step S113.

[0044] In step S113, it is determined whether the load list is empty. Since load 23c remains in the load list (No in step S113), the process returns to step S105.

[0045] In step S105, 23c is moved from the load list to the regeneration allowable list. The load list and the regeneration allowable list at this time are in the state of (f) in FIG. 4B, for example.

[0046] In step S106, the loads in the regeneration allowable list are loads 23b and 23c, and the sum of the maximum values of their regeneration powers is 15 kW, which exceeds the charging upper limit power of 9 kW of the DC / DC converter 25 (Yes in step S106), so the process proceeds to step S107. In step S107, move the load 23c that was last moved to the regeneration allowable list back to the load list. The load list and the regeneration allowable list at this time are, for example, in the state of (g) in FIG. 4B.

[0047] Next, in step S108, start the regeneration of the load 23b in the regeneration allowable list. In step S109, when the regeneration of the load 23b in the regeneration allowable list is completed, in step S110, delete the load 23b whose regeneration has been completed from the regeneration allowable list and empty the regeneration allowable list.

[0048] Next, in step S111, check the load list. Since the load 23c remains (No in step S111), return to step S105.

[0049] In step S105, move the load 23c from the load list to the regeneration allowable list. The load list and the regeneration allowable list at this time are, for example, in the state of (h) in FIG. 4B.

[0050] In step S106, the load in the regeneration allowable list is only the moved load 23c, and the maximum value of the regeneration power of the load 23c is 7 kW, which is less than or equal to the charging upper limit power of 9 kW of the DC / DC converter 25 (No in step S106), so proceed to step S113.

[0051] In step S113, determine whether the load list is empty. Since the load list is empty (Yes in step S113), proceed to step S108.

[0052] Next, in step S108, start the regeneration of the load 23c in the regeneration allowable list. In step S109, when the regeneration of the load 23c in the regeneration allowable list is completed, in step S110, delete the load 23a whose regeneration has been completed from the regeneration allowable list and empty the regeneration allowable list.

[0053] Next, in step S111, since the load list is checked and found to be empty (Yes in step S111), the regenerative control process ends.

[0054] In the first embodiment, as a result, as shown in FIG. 5, each load regenerates in order, and the total regenerative power is as shown in FIG. 6. Also, in the above, the priority order for stopping and regenerating the loads is load 23a, load 23b, load 23c. However, for example, if the loads are regenerated in descending order of regenerative power, the regeneration order will be load 23b, load 23c, load 23a. In this case, as a result, the total regenerative power is as shown in FIG. 7. Thus, while one or more loads are in the regenerative operation, the start time of load regeneration is adjusted with reference to the priority order of each load so that the total regenerative power does not exceed the charging upper limit power of the DC / DC converter 25.

[0055] <Embodiment 2> When the charging upper limit power of the DC / DC converter 25 of the storage battery 22 is sufficiently large Loads to be stopped: Load 23a, Load 23b, Load 23c Load 23a: Maximum regenerative power 6 kW, regenerative time 8 s Load 23b: Maximum regenerative power 8 kW, regenerative time 6 s Load 23c: Maximum regenerative power 7 kW, regenerative time 7 s Charging upper limit power of the DC / DC converter 25 for the storage battery 22: 17 kW It is assumed that the conversion capacity of the AC / DC converter 24 is sufficiently large. Note that the regenerative power characteristics, which are the regenerative power data of each load, are the same as those in FIG. 3.

[0056] The procedure of the regenerative control according to the second embodiment will be described below using the flowchart of FIG. 2 and the load list and regenerative permission list illustrated in FIGS. 8A and 8B. First, in step S101, loads 23a, 23b, and 23c are selected as the loads to be stopped by the operation unit 14. The priority order of stopping is load 23a, load 23b, load 23c.

[0057] Next, in step S102, a stop instruction is sent to each load by the operation unit 14 via the communication unit 13.

[0058] In step S103, loads 23a, 23b, and 23c are input as loads to be stopped in the load list, and nothing is input to the regeneration allowable list, which is in an empty state. The load list and the regeneration allowable list at this time are in the state of (a) in FIG. 8A, for example.

[0059] In step S104, it is determined whether there is a load in the load list whose maximum value of regenerative power exceeds the charging upper limit power of the DC / DC converter 25. Since the maximum value of the regenerative power of none of the loads exceeds the charging upper limit power of 17 kW of the DC / DC converter 25 (No in step S104), the process proceeds to step S105.

[0060] In step S105, load 23a, which is the load with the highest stop priority in the load list, is moved to the regeneration allowable list. The load list and the regeneration allowable list at this time are in the state of (b) in FIG. 8A, for example.

[0061] In step S106, the only load in the regeneration allowable list is load 23a, and the maximum value of the regenerative power of load 23a is 6 kW, which is less than or equal to the charging upper limit power of 17 kW of the DC / DC converter 25 (No in step S106), so the process proceeds to step S113.

[0062] In step S113, it is determined whether the load list is empty. Since loads 23b and 23c remain in the load list (No in step S113), the process returns to step S105.

[0063] In step S105, load 23b, which is a load with a high stop priority in the load list, is moved to the regeneration allowable list. The load list and the regeneration allowable list at this time are in the state of (c) in FIG. 8A, for example.

[0064] In step S106, the loads on the regeneration allowable list are load 23a and load 23b. The total of the maximum values of their regenerative powers is 14 kW, which is less than or equal to the charging upper limit power of 17 kW of the DC / DC converter 25. So, in step S106, it is No), and the process proceeds to step S113.

[0065] In step S113, it is determined whether the load list is empty. Since load 23c remains in the load list (No in step S113), the process returns to step S105.

[0066] In step S105, 23c is moved from the load list to the regeneration allowable list. At this time, the load list and the regeneration allowable list are in the state of, for example, (d) in Fig. 8A.

[0067] In step S106, the loads on the regeneration allowable list are load 23a, load 23b, and load 23c. The total of the maximum values of their regenerative powers is 21 kW, which exceeds the charging upper limit power of 17 kW of the DC / DC converter 25. So, (Yes in step S106), the process proceeds to step S107. In step S107, load 23c, which was last moved to the regeneration allowable list, is returned to the load list. At this time, the load list and the regeneration allowable list are in the state of, for example, (e) in Fig. 8B.

[0068] Next, in step S108, the regeneration of load 23a and load 23b on the regeneration allowable list is started. In step S109, when the regeneration of load 23a and load 23b on the regeneration allowable list is completed, in step S110, load 23a and load 23b whose regeneration has been completed are deleted from the regeneration allowable list, and the regeneration allowable list is emptied.

[0069] Next, in step S111, the load list is checked. Since load 23c remains (No in step S111), the process returns to step S105.

[0070] In step S105, load 23c is moved from the load list to the regeneration allowable list. The load list and the regeneration allowable list at this time are in the state of (f) in FIG. 8B, for example.

[0071] In step S106, the load in the regeneration allowable list is only the moved load 23c, and the maximum value of the regeneration power of load 23c is 7 kW, which is less than or equal to the charging upper limit power of 17 kW of the DC / DC converter 25 (No in step S106), so the process proceeds to step S113.

[0072] In step S113, it is determined whether the load list is empty. Since the load list is empty (Yes in step S113), the process proceeds to step S108.

[0073] Next, in step S108, the regeneration of load 23c in the regeneration allowable list is started. In step S109, when the regeneration of load 23c in the regeneration allowable list is completed, in step S110, the regenerated load 23c is deleted from the regeneration allowable list, and the regeneration allowable list is emptied.

[0074] Next, in step S111, the load list is checked and it is empty (Yes in step S111), so the regeneration control process ends.

[0075] In the second embodiment, as a result, each load is regenerated in order as shown in FIG. 9, and the waveform of the synthesized regenerative power is as shown in FIG. 10. Further, in the above, the priority order of load stop is load 23a, load 23b, and load 23c. However, for example, when the regeneration is performed in the order of the magnitude of the regenerative power, the regeneration order is load 23b, load 23c, and load 23a, and as a result, the waveform of the synthesized regenerative power is as shown in FIG. 11. Further, when the regeneration is performed in the order of the length of the regeneration time, the regeneration order is load 23a, load 23c, and load 23b, and as a result, the waveform of the synthesized regenerative power is as shown in FIG. 12. Thus, when one or a plurality of loads are in the regenerative operation, the regeneration start time of each load is adjusted with reference to the priority order of each load so that the total regenerative power does not exceed the charging upper limit power of the DC / DC converter 25.

[0076] As described above, the load control device according to the first embodiment is a load control device that controls the regeneration of the power of a plurality of loads connected to a DC bus to a storage battery connected via a DC / DC converter, and stores the regenerative power data of the plurality of loads and a preset charging upper limit power when charging the storage battery. A storage unit, and a control unit that controls the regeneration start time of each of the plurality of loads so as not to exceed the charging upper limit power during the regeneration operation of the plurality of loads. With this configuration, even if a plurality of loads regenerate simultaneously, it is possible to prevent the total value of the regenerative power of the loads from exceeding the charging upper limit power, for example, the rated power of the DC / DC converter, and it is possible to suppress the voltage rise of the DC bus.

[0077] Further, when the charging upper limit power of the DC / DC converter for the storage battery is large, a plurality of loads can be regenerated simultaneously, and the total regeneration time can be shortened, and it is possible to prevent a large amount of time from being required when the regenerative load stops.

[0078] Further, since the load control device holds the regenerative power data including the regenerative power and the regeneration time of each load, by considering them together with the priority order of each load, it is possible to control so as to shorten the time until all loads complete regeneration.

[0079] Furthermore, the DC power distribution system according to Embodiment 1 includes a DC bus, a plurality of regenerable loads connected to the DC bus, a storage battery connected to the DC bus via a DC / DC converter, and the above-described load control device. The load control device further includes a communication unit that communicates with a plurality of loads. With this configuration, even if a plurality of loads regenerate simultaneously, it is possible to prevent the total value of the regenerative power of the loads from exceeding the charging upper limit power of the DC / DC converter for the storage battery, and it is possible to efficiently utilize the regenerative power generated from the loads, contributing to energy saving. In addition, since overload can be avoided and power can be stored in the storage battery, a system capable of stably supplying DC voltage is realized. In addition, since the load control device has a communication unit, the regenerative control of each load can be performed by communication, facilitating the control and management of the regenerative power within the DC power distribution system within a preset range.

[0080] Embodiment 2. In this Embodiment 2, in the regenerative control, in addition to the regenerative power of the load, a control method considering the regeneration time will be described. The configuration and basic operation of the load control device 10 and the DC power distribution system 1 are the same as those described with reference to FIG. 1 of Embodiment 1, and the description thereof will be omitted.

[0081] <Operation of Load Control Device 10> FIGS. 13A and 13B are flowcharts showing the operation of the load control device 10 according to Embodiment 2, showing the control flow for creating a regeneration operation instruction for each load. Here, the charging upper limit power is a value held in the storage unit 11, and when there is no particular reason, the charging upper limit power of the DC / DC converter 25 for the storage battery 22 is input. The storage unit 11 receives input, for example, from the operation unit 14. First, in step S201, when a load to be stopped is selected, in step S202, the communication unit 13 transmits a stop instruction to the target load. Here, the selection of the load to be stopped and the stop instruction are executed by the operation unit 14. Also, in step S201, the order of stopping and regenerating the loads may be determined.

[0082] In step S203, it is determined whether there is a load for which the maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25 among the loads to be stopped. If there is no load for which the maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25 (No in step S203), the process proceeds to step S204. If there is a load for which the maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25 (Yes in step S203), it is regarded as an error occurrence, the process proceeds to step S212, it is stored in the storage unit 11 as error information, and the process ends.

[0083] In step S203, if there is no load for which the maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25, in step S204, the regenerative start times Tsta, Tstb, and Tstc of each load are defined as variables and initialized to 0 s. Here, although the number of loads is assumed to be three, namely load 23a, load 23b, and load 23c, it may be any number.

[0084] In step S205, the regenerative power waveforms of load 23a and load 23b are added. In step S206, it is determined whether the maximum value of the added combined regenerative power waveform exceeds the charging upper limit power of the DC / DC converter 25. If it exceeds (Yes in step S205), the process proceeds to step S213. If it is equal to or less than the charging upper limit power (No in step S205), the process proceeds to step S207.

[0085] In step S206, when the maximum value of the combined regenerative power waveform exceeds the charging upper limit power of the DC / DC converter 25, in step S213, the regenerative start time Tstb of load 23b is delayed by, for example, 0.1 s. Here, the delay time is set to 0.1 s, but this value is set to about 1% of the typical regenerative time of the connected load, and it may be longer than 0.1 s for equipment with a long regenerative time or shorter than 0.1 s for equipment with a short regenerative time. In step S206, until the maximum value of the combined regenerative power waveform becomes equal to or less than the charging upper limit power of the DC / DC converter 25, the process of delaying the regenerative start time Tstb of the load 23b in step S213 is repeated.

[0086] In step S207, the regenerative start time Tstb of the load 23b is adjusted, and the combined regenerative power waveform of the loads 23a and 23b, for which the maximum value of the combined regenerative power waveform is equal to or less than the charging upper limit power of the DC / DC converter 25, is held in the storage unit 11 as the regenerative power waveform AB.

[0087] Next, in step S208, the regenerative power waveform of the load 23c is added to the regenerative power waveform AB. In step S209, it is determined whether the maximum value of the added combined regenerative power waveform exceeds the charging upper limit power of the DC / DC converter 25. If it exceeds (Yes in step S209), the process proceeds to step S214. If it is equal to or less than the charging upper limit power (No in step S209), the process proceeds to step S210.

[0088] In step S214, the regenerative start time Tstc of the load 23c is delayed by, for example, 0.1 s. Here, although the delay time is set to 0.1 s, this value is set to about 1% of the typical regenerative time of the connected load, and may be made longer than 0.1 s for equipment with a long regenerative time, or may be made shorter than 0.1 s for equipment with a short regenerative time. In step S209, until the maximum value of the combined regenerative power waveform becomes equal to or less than the charging upper limit power of the DC / DC converter 25, the process of delaying the regenerative start time Tstc of the load 23c in step S214 is repeated.

[0089] Next, in step S210, the regenerative start times Tsta (=0 s), Tstb, and Tstc of the respective loads 23a, 23b, and 23c are held in the storage unit 11.

[0090] Finally, in step S211, corresponding to the regeneration start times Tsta (=0 s), Tstb, and Tstc of each load 23a, 23b, and 23c, the regeneration operation is started with the power waveforms of each load. When the regeneration of all loads is completed, the load stops the regeneration operation and the regeneration control process ends.

[0091] In FIGS. 13A and 13B, the number of loads is assumed to be three for the sake of illustration, but the number of loads is determined according to the convenience of the equipment or the like. Also, in FIGS. 13A and 13B, the order of adding the waveforms is assumed to be the load 23a, the load 23b, and the load 23c in that order, and this also becomes the order of regeneration. This order may be set in advance according to the convenience of the equipment, or all regeneration order patterns may be calculated and determined so that the regeneration time is the shortest.

[0092] As determined in step S203, even in the second embodiment, if there is a load whose maximum value of the regenerative power exceeds the charging upper limit power when considered individually, the battery side cannot charge all the power. When constructing the system of the second embodiment, it is desirable to select each load so that the regenerative power of a single load does not exceed the charging upper limit power of the DC / DC converter 25. If the regenerative power of a single load exceeds the charging upper limit power, the process ends as determined in step S203.

[0093] Hereinafter, an example of the regeneration control of the second embodiment will be described.

[0094] <Example 3> Loads to be stopped: Load 23a, Load 23b, Load 23c The regenerative power characteristics, which are the regenerative power data of each load, are as shown in FIG. 14. All are triangular waves with a maximum regenerative power of 8 kW and a regenerative time of 8 s. Charging upper limit power of the DC / DC converter 25 for the battery 22: 8 kW It is assumed that the conversion capacity of the AC / DC converter 24 is sufficiently large.

[0095] Consider the case where each load stops and regenerates under this condition. When two loads start regenerating simultaneously, the sum of the maximum values of the regenerative power becomes 16 kW, exceeding the charging upper limit power of 8 kW of the DC / DC converter 25. At this time, the load control device 10 performs regenerative control according to the flowcharts of FIGS. 13A and 13B. Note that FIG. 15 shows the progress of the composite waveform of the regenerative power by a plurality of loads during regenerative control.

[0096] First, in step S201, the load to be stopped is selected. In this Example 3, the loads to be stopped are load 23a, load 23b, and load 23c. Here, the order in which the loads are stopped and regenerated is load 23a, load 23b, and load 23c. In step S202, the communication unit 13 transmits a stop instruction to the target load. The selection of the load to be stopped in step S201 and the stop instruction in step S202 are executed by the operation unit 14.

[0097] In step S203, it is determined whether there is a load whose maximum value of the regenerative power exceeds the charging upper limit power of the DC / DC converter 25 for the load to be stopped. Since the maximum regenerative power of each load is 8 kW and does not exceed the charging upper limit power of 8 kW of the storage battery 22 (No in step S203), the process proceeds to step S204.

[0098] In step S204, the regenerative start times Tsta, Tstb, and Tstc of each of the loads 23a, 23b, and 23c are defined as variables and initialized to 0 s.

[0099] In step S205, the regenerative power waveforms of load 23a and load 23b are added. In FIG. 15(a), the waveform of the added composite regenerative power is shown by a solid line. In step S206, since the maximum value of the composite regenerative power waveform is 16 kW and exceeds the charging upper limit power of 8 kW of the DC / DC converter 25 (Yes in step S205), the process proceeds to step S213.

[0100] In step S213, the regeneration start time Tstb of load 23b is delayed by 0.1 s, and the process returns to step S205, where the regenerative power waveforms of load 23a and load 23b are added. In step S206, since the maximum value of the combined regenerative power waveform is 15.8 kW, which exceeds the charging upper limit power of 8 kW of the DC / DC converter 25 (Yes in step S205), the process proceeds to step S213.

[0101] Again, in step S213, the regeneration start time Tstb of load 23b is delayed by 0.1 s, and the process returns to step S205, where the regenerative power waveforms of load 23a and load 23b are added. The operations of steps S205, S208, and S213 are repeated. For example, the combined regenerative power waveform obtained by adding the regenerative power waveforms of load 23a and load 23b when the regeneration start time Tstb of load 23b reaches 2 s is shown in Fig. 15(b). Even in this state, in step S206, the maximum value of the combined regenerative power waveform is 12 kW, which is determined to exceed the charging upper limit power of 8 kW of the DC / DC converter 25 (Yes in step S205), and the process proceeds to step S213.

[0102] Again, in step S213, the regeneration start time Tstb of load 23b is delayed by 0.1 s, and the process returns to step S205, where the regenerative power waveforms of load 23a and load 23b are added, and the operations of steps S205, S208, and S213 are further repeated.

[0103] The combined regenerative power waveform obtained by adding the regenerative power waveforms of load 23a and load 23b when the regeneration start time Tstb of load 23b reaches 4 s is shown in Fig. 15(c). In step S206, the maximum value of the combined regenerative power waveform is 8 kW, which is equal to or less than the charging upper limit power of 8 kW of the DC / DC converter 25 (No in step S205), so the process proceeds to step S207. In step S207, the combined regenerative power waveform of load 23a and load 23b is held in the storage unit 11 as the regenerative power waveform AB.

[0104] Next, in step S208, the regenerative power waveform AB and the regenerative power waveform of the load 23c are added. In Fig. 15(d), the waveform of the added combined regenerative power is shown by a solid line. In step S209, the maximum value of the combined regenerative power waveform is 16 kW, which exceeds the charging upper limit power of 8 kW of the DC / DC converter 25. Therefore, (Yes in step S208), the process proceeds to step S214.

[0105] In step S214, the regenerative start time Tstc of the load 23c is delayed by 0.1 s, and the process returns to step S208. The regenerative power waveforms of the loads 23a and 23b are added. In step S209, it is determined whether the maximum value of the combined regenerative power waveform exceeds the charging upper limit power of 8 kW of the DC / DC converter 25.

[0106] The operations of steps S208, S209, and S214 are repeated. When the regenerative start time Tstb of the load 23c reaches 8 s, the maximum value of the combined regenerative power waveform obtained by adding the regenerative power waveform AB and the regenerative power waveform of the load 23c is 8 kW, which is equal to or less than the charging upper limit power of 8 kW of the DC / DC converter 25. Therefore, (No in step S205), the process proceeds to step S210. The combined regenerative power waveform at this time is shown in Fig. 16.

[0107] In step S210, the regenerative start times Tsta, Tstb, and Tstc of the respective loads 23a, 23b, and 23c are held in the storage unit 11. Specifically, Tsta = 0 s, Tstb = 4 s, and Tstc = 8 s are held in the storage unit 11.

[0108] In step S211, regenerations of the respective loads 23a, 23b, and 23c are started according to the determined regenerative start times Tsta, Tstb, and Tstc. Specifically, as shown in Fig. 16, regenerations of the respective loads 23a, 23b, and 23c are performed. When the regenerations of all the loads are completed, the load stops the regenerative operation, and the regenerative control process ends.

[0109] As described above, when the regenerative power is not constant, instead of completely shifting the regenerative time of each load, it is possible to provide a time during which a plurality of loads regenerate simultaneously. As a result, the total regenerative time can be shortened, and thus the stop time of the normal operation of the load for regeneration can be suppressed.

[0110] <Example 4> Note that even when the regenerative power of the load is constant, the second embodiment is applicable. For example, in Example 2 of the first embodiment, the regenerative power waveform in FIG. 10 can be as shown in FIG. 17. That is, when the regenerative power waveform of load 23c is added to the regenerative power waveform obtained by adding the regenerative power waveform of load 23b to the regenerative power waveform of load 23a and the regenerative start time Tstc of load 23c is shifted, the regenerative start time Tstc (= 6 s) of load 23c can be set to 6 s after the end of regeneration of load 23b, and the regeneration of load 23c can be started below the charging upper limit power of the storage battery. Thereby, the total regenerative time can be shortened compared to the case of the first embodiment.

[0111] As described above, according to the second embodiment, the same effects as those of the first embodiment are achieved. Further, when regenerating a plurality of loads, the regenerative start time can be finely adjusted, so that the regenerative time can be further shortened.

[0112] The load control device 10 in the above-described first and second embodiments is shown in FIG. 18 as an example of hardware, and includes an arithmetic processing unit 101, a ROM (Read Only Memory) storing a program for executing the functions of each functional unit, a storage device 102 including RAM (Random Access Memory) for storing each data of the execution results of each functional unit which are the calculation results by the program, and data such as regenerative power data acquired in advance or input, an input / output circuit 103, and a communication circuit 104. The arithmetic processing unit 101 executes the program input from the storage device 102.

[0113] As a communication module, the communication circuit 104 can use, for example, those conforming to standards such as LAN (Local Area Network) and Bluetooth (registered trademark). Depending on the communication environment with the load, wireless or wired can be selected, and the communication method can be selected.

[0114] Note that for the arithmetic processing unit 101, processors such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor) are applicable. Also, dedicated hardware may be applied to the arithmetic processing unit 101. When the arithmetic processing unit 101 is dedicated hardware, the arithmetic processing unit 101 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0115] Also, in the load control device 10, each functional unit may be realized by an individual arithmetic processing unit, or they may be realized together by one arithmetic processing unit. Furthermore, each functional unit of the load control device 10 can realize the above-mentioned respective functions by hardware, software, or a combination thereof, such as realizing some functions as a dedicated hardware by an arithmetic processing unit and other functions by software.

[0116] Also, each component described in the above-described embodiment is assumed to be either software or firmware, or the corresponding hardware, and in both concepts, each component is referred to as a "part" or a "processing circuit", etc.

[0117] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more of the embodiments are not limited to the application of a particular embodiment, but are applicable to the embodiments alone or in various combinations. Accordingly, countless variations not illustrated are envisioned within the scope of the technology disclosed in this specification. For example, it is assumed to include cases where at least one component is deformed, added, or omitted, and further cases where at least one component is extracted and combined with components of other embodiments.

[0118] Hereinafter, aspects of the present disclosure will be collectively described as appendices.

[0119] (Appendix 1) A load control device that controls the regeneration of the power of a plurality of loads connected to a DC bus to a storage battery connected to the DC bus via a DC / DC converter, a storage unit that holds the regeneration power data of a plurality of the loads and a preset charge upper limit power when charging the storage battery; a control unit that controls the regeneration start times of a plurality of the loads so as not to exceed the charge upper limit power during the regeneration operation of the plurality of the loads. A load control device comprising the same. (Appendix 2) The load control device according to Appendix 1, wherein the regeneration power data includes the regeneration power and regeneration time of the load. (Appendix 3) The load control device according to Appendix 1 or 2, wherein the control unit controls the regeneration start time according to the priority order of each of the plurality of the loads. (Appendix 4) The load control device according to any one of Appendices 1 to 3, wherein the control unit regenerates a plurality of the loads simultaneously so as not to exceed the charge upper limit power. (Appendix 5) For a plurality of the loads having a constant pattern of regeneration power at the regeneration time, the control unit, When the total value of the regenerative power of the plurality of loads does not exceed the charging upper limit power, the plurality of loads are regenerated simultaneously. When the total value of the regenerative power of the plurality of loads exceeds the charging upper limit power, control is performed to delay the regeneration start time of the load to which the regenerative power was last added and not regenerate it simultaneously with the other loads. The load control device according to any one of Appendices 1 to 4. (Appendix 6) The preset charging upper limit power is the rated power of the DC / DC converter. The load control device according to any one of Appendices 1 to 5. (Appendix 7) The load control device according to any one of Appendices 1 to 6, the DC bus, a plurality of regenerable loads connected to the DC bus, the storage battery connected to the DC bus via the DC / DC converter, A DC power distribution system comprising: The load control device includes a communication unit that communicates with the plurality of loads. A DC power distribution system.

Explanation of Signs

[0120] 1: DC power distribution system, 3: DC bus, 10: Load control device, 11: Storage unit, 12: Control unit, 13: Communication unit, 14: Operation unit, 21: Commercial power supply, 22: Storage battery, 23a, 23b, 23c: Loads, 24: AC / DC converter, 25: DC / DC converter, 26a, 26b, 26c: Communication lines, 101: Arithmetic processing device, 102: Storage device, 103: Input / output circuit, 104: Communication circuit.

Claims

1. A load control device that controls the regeneration of the power of a plurality of loads connected to a DC bus to a storage battery connected to the DC bus via a DC / DC converter, a storage unit that holds the regeneration power data of a plurality of the loads and a preset charging upper limit power when charging the storage battery; and a control unit that controls the regeneration start times of the plurality of loads so as not to exceed the charging upper limit power during the regeneration operation of the plurality of loads. A load control device comprising:

2. The load control device according to claim 1, wherein the regeneration power data includes the regeneration power and regeneration time of the load.

3. The load control device according to claim 1 or 2, wherein the control unit controls the regeneration start time according to the priority order of each of the plurality of loads.

4. The load control device according to claim 1 or 2, wherein the control unit regenerates a plurality of the loads simultaneously so as not to exceed the charging upper limit power.

5. For a plurality of the loads having a constant pattern of regeneration power at the regeneration time, the control unit, when the total value of the regeneration power of the plurality of loads does not exceed the charging upper limit power, regenerates the plurality of loads simultaneously, when the total value of the regeneration power of the plurality of loads exceeds the charging upper limit power, performs control to delay the regeneration start time of the load to which the regeneration power was last added and not regenerate it simultaneously with the other loads. The load control device according to claim 1 or 2.

6. The load control device according to claim 1 or 2, wherein the preset charging upper limit power is the rated power of the DC / DC converter.

7. The load control device according to claim 1 or 2, the DC bus, a plurality of the regenerable loads connected to the DC bus, The storage battery connected to the DC bus via the DC / DC converter, A DC power distribution system comprising: The load control device includes a communication unit that communicates with a plurality of the loads, and is a DC power distribution system.

Images