JP2019058053A - Direct current power supply system - Google Patents

Abstract

To operate a plurality of direct current power source connected with a direct bus according to priority.SOLUTION: A wind power generator 10 is a first direct current power source. The first direct current power source has the highest priority, and outputs direct current voltage to a direct current bus 100. A hydraulic power generator 20, a geothermal power generator 30, a photovoltaic power generator 40, and a system interconnection device 70 are second direct current power sources. Each second direct current power source has its upper limit of output voltage determined according to priority. Each second direct current power source outputs direct current voltage to the direct current bus 100 when voltage of the direct current bus 100 is equal to or less than the upper limit of output voltage. The hydraulic power generator 20 and geothermal power generator 30 each output direct current voltage when the voltage of the direct current bus 100 is, for example, equal to or less than 290 V. The photovoltaic power generator 40 outputs direct current voltage when the voltage of the direct current bus 100 is, for example, equal to or less than 280 V. The system interconnection device 70 outputs direct current voltage when the voltage of the direct current bus 100 is, for example, equal to or less than 260 V.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a DC power supply system that supplies DC power.

  Patent Document 1 discloses a distributed power supply system in which a plurality of distributed power supply units are connected via a DC bus. This distributed power supply system allows the voltage fluctuation of the DC bus within a predetermined range, and autonomously and cooperatively operates each distributed power supply unit based on the voltage value of the DC bus. The distributed power supply system includes a wind power generation unit, a solar power generation unit, a power storage unit, and a system linkage unit. The grid connection unit mutually supplies power between the DC bus of the distributed power supply system and the external AC power system.

JP 2003-339118 A

In addition to wind power generation units and solar power generation units, power generation devices using natural energy include hydroelectric power generation devices and geothermal power generation devices. Of these, the wind power generation unit needs to be preferentially operated because the windmill may be destroyed if stopped in a strong wind. It is desirable to operate the hydroelectric generator as much as possible to prevent the destruction of the turbine.
However, in the distributed power supply system described in Patent Document 1, although each distributed power supply unit autonomously performs cooperative operation, each distributed power supply unit cannot be operated according to priority. For example, it is not possible to stop the solar power generation unit and operate only the wind power generation unit. Further, when the voltage of the DC bus becomes, for example, 380 V or more, the wind power generation unit is also stopped.

  An object of the present invention is to provide a DC power supply system capable of operating a plurality of DC power sources connected to a DC bus according to priority.

In order to achieve the above object, the DC power supply system of the present invention is:
DC bus,
One or more first DC power sources having the highest priority and outputting a DC voltage to the DC bus;
The priority is second or lower, the upper limit of the output voltage is determined according to the priority, and the DC voltage is output to the DC bus when the voltage of the DC bus is lower than the upper limit of the output voltage 1 Two or more second DC power sources;
It is characterized by providing.

Preferably, the DC power supply system of the present invention is
The second DC power source includes two or more DC power sources having different priorities.

Preferably, the DC power supply system of the present invention is
A system in which the second DC power source has the lowest priority among the second DC power sources, and converts an AC voltage supplied from an AC power system into a DC voltage and outputs the DC voltage to the DC bus. A linking device is included.

Preferably, the DC power supply system of the present invention is
The storage battery of the rated voltage according to the priority order and the charging of the storage battery are stopped when it is determined that the storage battery is overcharged, and the discharge of the storage battery is stopped when it is determined that the storage battery is overdischarged And the storage battery includes one or more power storage devices connected to the DC bus through the protection circuit.

Preferably, the DC power supply system of the present invention is
The power storage device having the higher priority than the grid linking device is provided.

Preferably, the DC power supply system of the present invention is
The power storage device having the lower priority than the grid connection device is provided.

Preferably, the DC power supply system of the present invention is
The first DC power source has no upper limit on the output voltage,
When the DC voltage of the DC bus is equal to or higher than a predetermined voltage greater than the upper limit of the output voltage determined for the second DC power source having the highest priority among the second DC power sources, Comprising a power consuming device that consumes power of the DC bus;
It is characterized by

Preferably, the DC power supply system of the present invention is
The first DC power source includes one or more wind power generators;
The power consuming device operates as a brake for suppressing or stopping rotation of the wind turbine of the wind turbine generator;
It is characterized by that.

Preferably, the DC power supply system of the present invention is
The second DC power source includes one or more photovoltaic power generation devices including a solar cell array, the solar cell array including a plurality of strings;
The upper limit of the output voltage is determined for each of the strings according to the priority order,
It is characterized by that.

  According to the present invention, it is possible to operate a plurality of DC power sources connected to a DC bus according to priority.

It is a figure which shows an example of a structure of the DC power supply system which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the priority of each apparatus contained in the DC power supply system of FIG. It is a figure which shows an example of the connection of the resistive element contained in an electric power consumption apparatus, and a DC bus. FIG. 3A illustrates an example in which the switch is provided on the high potential line side. FIG. 3B illustrates an example in which the switch is provided on the low potential line side. It is a figure which shows an example of the connection of the hydroelectric generator contained in a hydroelectric generator, and a DC bus. It is a figure which shows an example of the connection of the geothermal power generator contained in a geothermal power generator, and a DC bus. It is a figure which shows an example of a connection of each string and DC bus | bath in case a solar power generation device contains a solar cell array and a solar cell array contains a some string. It is a figure which shows an example of a structure of the electrical storage apparatus for normal. It is a figure which shows an example of a structure of an emergency electrical storage apparatus. It is a figure which shows an example of a structure of the DC power supply system which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the priority of each apparatus contained in the DC power supply system of FIG. It is a figure which shows an example of a structure of the DC power supply system which concerns on the 3rd Embodiment of this invention. It is a figure which shows an example of the priority of each apparatus contained in the DC power supply system of FIG.

  Hereinafter, a DC power supply system according to an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, common constituent elements are denoted by the same reference numerals, and repeated explanation is omitted.

FIG. 1 shows an example of the configuration of a DC power supply system 1 according to the first embodiment of the present invention.
The DC power supply system 1 includes a wind power generator 10, a hydroelectric generator 20, a geothermal power generator 30, a solar power generator 40, a normal power storage device 50, an emergency power storage device 60, and a grid linking device 70. , A power consuming device 80, a plurality of loads 90, and a DC bus 100.
As shown in FIG. 2, priorities are assigned in advance to the power generation devices 10, 20, 30, 40, the power storage devices 50, 60, and the system linkage device 70. These priorities are set when the DC power supply system 1 is not in operation, and cannot be changed while the DC power supply system 1 is in operation. Each of these devices is connected to the DC bus 100 and outputs a DC voltage to the DC bus 100 according to the priority order.

The wind power generator 10 has the highest priority. The wind power generator 10 has no upper limit on the output voltage. The wind power generator 10 is an ordinary general wind power generator. The wind turbine generator 10 stops the output of the DC voltage to the DC bus 100 when the windmill stops or the rotation speed decreases. Moreover, the wind power generator 10 may stop the output of the DC voltage to the DC bus 100 by output control.
The wind power generator 10 is an example of a first DC power source in the present invention. The first DC power source has the highest priority.

The hydroelectric power generation device 20, the geothermal power generation device 30, the solar power generation device 40, and the system linkage device 70 are examples of the second DC power source in the present invention. Each second DC power source has an upper limit on the output voltage according to the priority order. Each second DC power source has a device for measuring the voltage of the DC bus 100. Each second DC power source outputs a DC voltage to the DC bus 100 when the measured voltage of the DC bus 100 is equal to or lower than the upper limit of the output voltage.
In the example of FIG. 2, the priority order of the hydroelectric generator 20 and the geothermal generator 30 is the second, and is the highest among the second DC power sources. The upper limit of the output voltage in the hydroelectric generator 20 and the geothermal power generator 30 is 290V. The priority of the solar power generation device 40 is the third. The upper limit of the output voltage in the solar power generation device 40 is 280V.

  The normal power storage device 50 and the emergency power storage device 60 include storage batteries with rated voltages according to priority. In the example of FIG. 2, the priority order of the normal power storage device 50 is fifth. The rated voltage of the storage battery included in the normal power storage device 50 is 264V. The priority order of the emergency power storage device 60 is seventh. The rated voltage of the storage battery included in the emergency power storage device 60 is 252V. Each power storage device 50, 60 stops charging the storage battery when overcharged, and stops discharging the storage battery when overdischarged.

  In the example of FIG. 2, the priority of the grid connection device 70 is the sixth, and the priority is the lowest among the second DC power sources. The upper limit of the output voltage in the grid connection device 70 is 260V. When the voltage of the DC bus 100 is equal to or lower than the upper limit (260 V) of the output voltage, the grid connection device 70 converts the AC voltage supplied from the external AC power system 200 into a DC voltage and converts it to the DC bus 100. Output. The grid connection device 70 supplies power to the DC bus 100 when the output voltage of each power generation device due to natural energy decreases. The priority of the normal power storage device 50 is higher than the priority of the grid linking device 70. Further, the priority order of the emergency power storage device 60 is lower than the priority order of the system linkage device 70.

In each second DC power source, the upper limit of the set output voltage can be changed within a range in which the priority order does not change during operation of the DC power supply system 1.
For example, in the example of FIG. 2, the range in which the upper limit of the output voltage can be changed for the hydroelectric power generator 20 and the geothermal power generator 30 is 280 V or more. The range in which the upper limit of the output voltage of the solar power generation device 40 can be changed is 264V or more and 290V or less. The range in which the upper limit of the output voltage can be changed for the grid connection device 70 is 252V or more and 264V or less.
For example, when the DC power feeding system 1 is operating with the upper limit of the output voltage of the hydroelectric generator 20 and the geothermal power generator 30 being 290 V and the upper limit of the output voltage of the solar power generator 40 being 280 V, the hydroelectric generator 20 and the geothermal power are operating. All the upper limits of the output voltage of the power generator 30 and the solar power generator 40 can be changed to 295V. In this case, although the upper limit of the output voltage of the hydroelectric generator 20, the geothermal power generator 30, and the solar power generator 40 is the same, the priority of the hydroelectric generator 20 and the geothermal power generator 30 is second, and the solar power generation It is assumed that the priority of the device 40 is the third, and that these priorities are not changed. In addition, although the upper limit of the output voltage in the solar power generation device 40 is changed exceeding 290V, the priority of the hydroelectric power generation device 20, the geothermal power generation device 30, and the solar power generation device 40 has not changed.

When the DC voltage of the DC bus 100 is equal to or higher than a predetermined voltage (for example, 295 V) greater than the upper limit (290 V in the example of FIG. 2) of the output voltage in the hydroelectric power generator 20 and the geothermal power generator 30 The power of the DC bus 100 is consumed. The hydroelectric generator 20 and the geothermal generator 30 have the highest priority among the second DC power sources.
The load 90 consumes power. The load 90 is, for example, a television, a refrigerator, an air conditioner, a computer, lighting, a house, a factory, or the like. The load 90 is also prioritized. When the DC voltage of the DC bus 100 decreases, the load 90 is disconnected from the DC bus 100 in order of priority. For example, air conditioning has the lowest priority, and is disconnected from the DC bus 100 when the voltage of the DC bus 100 is 260V. The computer has the highest priority and is disconnected from the DC bus 100 when the voltage of the DC bus 100 drops to 240V.
In FIG. 1, only one power generation device 10, 20, 30, 40 and each power storage device 50, 60 are shown, but a plurality of devices may be connected to the DC bus 100. For example, a plurality of wind power generators 10 and a plurality of solar power generators 40 may be connected to the DC bus 100.

As shown in FIG. 3, the power consuming device 80 includes a resistance element 81, a switch SW, and a control unit 82. The switch SW can be realized by a relay or a semiconductor switching element, for example. When the DC voltage of the DC bus 100 is equal to or higher than a predetermined voltage (for example, 295 V) higher than the upper limit (290 V in the example of FIG. 2) of the output voltage in the hydroelectric power generator 20 and the geothermal power generator 30, the control unit 82 switches SW is closed and the resistance element 81 is connected to the DC bus 100. At this time, the resistance element 81 consumes the power of the DC bus 100.
Note that the switch SW may be provided on the high potential line LH side as shown in FIG. 3A, or may be provided on the low potential line LL side as shown in FIG. 3B. . Further, it may be provided on both the high potential line LH side and the low potential line LL side.

The wind power generator 10 outputs a large amount of power when the wind is very strong. If there is no sufficient load on the output of the wind power generator 10 at this time, the wind turbine may overrotate and be damaged by the wind power. When the wind power generator 10 outputs large power, the power consuming device 80 consumes surplus power. At this time, the wind power generator 10 is electrically braked, and the rotation of the windmill is suppressed or stopped.
A device that consumes electric power may be installed in the wind turbine generator 10. However, when there are a plurality of wind power generators 10 in the DC power supply system 1, by providing the power consuming device 80, a device that consumes power from each wind power generator 10 can be omitted, and its cost is reduced. Can be reduced.
Even if a high voltage is applied to the DC bus 100 due to an accident or the like, the power consuming device 80 consumes abnormal power. For this reason, damage to each device connected to the DC bus 100 can be prevented.

As shown in FIG. 4, the hydroelectric generator 20 includes a hydroelectric generator 21, a switch SW, and a control unit 22. In the example of FIG. 2, the priority of the hydroelectric generator 20 is second, and the upper limit of the output voltage is 290V. When the DC voltage of the DC bus 100 is 290 V or less, the control unit 22 closes the switch SW and connects the hydroelectric generator 21 and the DC bus 100. The structure in which the hydroelectric generator 20 includes the control unit 22 and the switch SW is merely an example. The hydroelectric generator 20 may have another structure as long as it is a hydroelectric generator that outputs a DC voltage to the DC bus 100 when the voltage of the DC bus 100 is 290 V or less. For example, the hydroelectric generator 20 may be a hydroelectric generator that can output a voltage up to 290V.
As shown in FIG. 5, the geothermal power generation apparatus 30 includes a geothermal power generator 31, a switch SW, and a control unit 32. In the example of FIG. 2, the priority of the geothermal power generation apparatus 30 is second, and the upper limit of the output voltage is 290V. When the DC voltage of the DC bus 100 is 290 V or less, the control unit 32 closes the switch SW and connects the geothermal power generator 31 and the DC bus 100. In addition, the structure in which the geothermal power generation apparatus 30 has the control part 32 and switch SW is only an illustration. The geothermal power generation apparatus 30 may have another structure as long as it is a geothermal power generation apparatus that outputs a DC voltage to the DC bus 100 when the voltage of the DC bus 100 is 290 V or less. For example, the geothermal power generation apparatus 30 may be a geothermal power generation apparatus that can output a voltage up to 290V.

  FIG. 2 shows an example in which the upper limit of the output voltage of the solar power generation device 40 is single (280 V), but the solar power generation device 40 includes a solar cell array 41 as shown in FIG. The array 41 may include a plurality of strings 42, and each string 42 may be connected to the DC bus 100 via the switch SW. The solar power generation device 40 has a control unit 43. When the solar power generation device 40 has this structure, the upper limit of the output voltage can be set for each string 42. Thereby, when the voltage of the DC bus 100 is equal to or lower than the upper limit of the output voltage determined for each string 42, the control unit 43 closes the switch SW and causes the DC bus 100 to output the DC voltage for each string 42. it can. In addition, the structure in which the solar power generation device 40 includes the control unit 43 and the switch SW is merely an example. The solar power generation device 40 has another structure as long as each string 42 outputs a DC voltage to the DC bus 100 when the voltage of the DC bus 100 is equal to or lower than the upper limit determined for each string 42. It may be. For example, the solar power generation device 40 may be a solar power generation device in which each string 42 can output a voltage up to the upper limit of the output voltage determined for each string 42.

As shown in FIG. 7, the normal power storage device 50 includes a storage battery 51 and a protection circuit 52. The rated voltage of the storage battery 51 is 264 V in the examples of FIGS. 2 and 7. This is higher than the upper limit (260 V in the example of FIG. 2) of the output voltage in the grid connection device 70. The storage battery 51 is connected to the DC bus 100 via the protection circuit 52.
The protection circuit 52 stops the charging of the storage battery 51 when it is determined that the storage battery 51 is overcharged, and stops the discharge of the storage battery 51 when it is determined that the storage battery 51 is overdischarged.
Specifically, the protection circuit 52 determines that the battery is overcharged when the voltage of the DC bus 100 is higher than the rated voltage and exceeds a predetermined overcharge determination voltage that does not cause overcharge of the storage battery 51. Stop. Alternatively, the protection circuit 52 determines overcharge when the voltage between the positive and negative electrode terminals of the storage battery 51 exceeds the overcharge determination voltage, and stops charging the storage battery 51. Here, the overcharge determination voltage does not necessarily have to be a limit voltage at which the storage battery 51 is overcharged. The overcharge determination voltage may be a voltage lower than the limit voltage at which the storage battery 51 is overcharged.

Further, the protection circuit 52 determines that overdischarge occurs when the voltage of the DC bus 100 is lower than the rated voltage and falls below a predetermined overdischarge determination voltage that does not cause overdischarge of the storage battery 51, and stops discharge of the storage battery 51. . Alternatively, the protection circuit 52 determines overdischarge when the voltage between the positive and negative electrode terminals of the storage battery 51 is lower than the overdischarge determination voltage, and stops the discharge of the storage battery 51. Here, the overdischarge determination voltage may not necessarily be a limit voltage at which the storage battery 51 is overdischarged. The overdischarge determination voltage may be a voltage higher than a limit voltage at which the storage battery 51 is overdischarged.
The protection circuit 52 may determine overcharge and overdischarge for each cell included in the storage battery 51. That is, the protection circuit 52 may determine that the entire storage battery 51 is overcharged when any cell is determined to be overcharged, and stop charging the storage battery 51. Further, the protection circuit 52 may determine that the entire storage battery 51 is overdischarged when any cell is determined to be overdischarged, and stop the discharge of the storage battery 51.

  7 shows an example in which the storage battery 51 is connected to the DC bus 100 via the protection circuit 52 in the normal power storage device 50. However, in addition to the protection circuit 52, a DC / DC converter is used to store the storage battery 51. Can be boosted by a DC / DC converter and output to the DC bus 100, and the voltage of the DC bus 100 can be stepped down by the DC / DC converter and input to the storage battery 51. In this configuration, the rated voltage (for example, 264 V) of the storage battery 51 refers to a voltage obtained by boosting the actual output voltage of the storage battery 51 by a DC / DC converter. In the case of this configuration, by changing the voltage boosted by the DC / DC converter, the rated voltage of the normal power storage device 50 can be changed within a range in which the priority order does not change during operation of the DC power supply system 100.

As shown in FIG. 8, emergency power storage device 60 includes a storage battery 61 and a protection circuit 62. The rated voltage of the storage battery 61 is 252 V in the examples of FIGS. 2 and 8. This is lower than the upper limit (260 V in the example of FIG. 2) of the output voltage in the grid connection device 70.
Similarly to the protection circuit 52, the protection circuit 62 stops the charging of the storage battery 61 when it is determined that the storage battery 61 is overcharged, and stops the discharge of the storage battery 61 when it is determined that the storage battery 61 is overdischarged. Let
Emergency power storage device 60 outputs a DC voltage to DC bus 100 in an emergency. For example, the emergency power storage device 60 has a DC voltage applied to the DC bus 100 when all the power generation devices 10, 20, 30, 40 are stopped, the normal power storage device 50 is empty, and the power system 200 is out of power. Is output.

  Note that the emergency power storage device 60 also uses a DC / DC converter in addition to the protection circuit 62 in the same manner as the normal power storage device 50, and boosts the output voltage of the storage battery 61 by the DC / DC converter and outputs it to the DC bus 100. Alternatively, the voltage of the DC bus 100 may be stepped down by a DC / DC converter and input to the storage battery 61. In this configuration, the rated voltage (for example, 252 V) of the storage battery 61 refers to a voltage obtained by boosting the actual output voltage of the storage battery 61 by a DC / DC converter. In the case of this configuration, by changing the voltage boosted by the DC / DC converter, the rated voltage of the emergency power storage device 60 can be changed within a range where the priority does not change during operation of the DC power supply system 100.

FIG. 9 shows an example of the configuration of the DC power supply system 2 according to the second embodiment of the present invention.
The DC power supply system 2 includes a solar power generation device 45, a normal power storage device 50, a system linkage device 70, a plurality of loads 90, and a DC bus 100.
The solar power generation device 45, the normal power storage device 50, and the grid linking device 70 are prioritized as shown in FIG. Each of these devices 45, 50, and 70 is connected to the DC bus 100, and outputs a DC voltage to the DC bus 100 according to priority.
The solar power generation device 45 has the highest priority. An upper limit of the output voltage is not set for the solar power generation device 45. The solar power generation device 45 can output a DC voltage to the DC bus 100 up to a maximum output voltage determined by its performance. Note that the solar power generation device 45 is a normal general solar power generation device including a solar battery. The solar power generation device 45 is an example of the first DC power source in the present invention, similarly to the wind power generation device 10 according to the first embodiment.

In the example of FIG. 10, the priority order of the normal power storage device 50 is second. The rated voltage of the storage battery included in the normal power storage device 50 is 264V. The normal power storage device 50 is the same as the normal power storage device 50 according to the first embodiment.
In the example of FIG. 10, the priority order of the system linkage device 70 is the third. The upper limit of the output voltage in the grid connection device 70 is 260V. The grid linking device 70 is the same as the grid linking device 70 according to the first embodiment. The grid linking device 70 is an example of a second DC power source in the present invention.
Even in the DC power supply system 2 according to the second embodiment, the priority order is set when the DC power supply system 2 is not operating, and cannot be changed while the DC power supply system 2 is operating. However, in the grid linking device 70 that is the second DC power source, the upper limit of the set output voltage can be changed within a range in which the priority does not change during operation of the DC power supply system 2. For example, in the example of FIG. 10, the upper limit of the output voltage can be changed in the range of 264 V or less for the system linkage device 70.

FIG. 11 shows an example of the configuration of the DC power supply system 3 according to the third embodiment of the present invention.
The DC power supply system 3 includes a wind power generator 10, a normal power storage device 50, a system linkage device 70, a power consuming device 80, a plurality of loads 90, and a DC bus 100.
The wind power generation apparatus 10, the normal power storage apparatus 50, and the system linkage apparatus 70 are prioritized as shown in FIG. Each of these devices 10, 50, 70 is connected to the DC bus 100, and outputs a DC voltage to the DC bus 100 according to priority.
The wind power generator 10 has the highest priority. The wind turbine generator 10 is the same as the wind turbine generator 10 according to the first embodiment. The wind power generator 10 is an example of a first DC power source in the present invention.

In the example of FIG. 12, the priority order of the normal power storage device 50 is the second. The rated voltage of the storage battery included in the normal power storage device 50 is 264V. The normal power storage device 50 is the same as the normal power storage device 50 according to the first embodiment.
In the example of FIG. 12, the priority order of the grid linking device 70 is the third. The upper limit of the output voltage in the grid connection device 70 is 260V. The grid linking device 70 is the same as the grid linking device 70 according to the first embodiment. The grid linking device 70 is an example of a second DC power source in the present invention.
The power consuming device 80 consumes the power of the DC bus 100 when the DC voltage of the DC bus 100 is equal to or higher than a predetermined voltage higher than the upper limit of the output voltage in the system linkage device 70 (260 V in the example of FIG. 12). In the present embodiment, the predetermined voltage is desirably a voltage equal to or higher than the overcharge determination voltage of the normal power storage device 50, for example.
Also in the DC power supply system 3 according to the third embodiment, the priority order is set when the DC power supply system 3 is not in operation, and cannot be changed while the DC power supply system 3 is in operation. However, the upper limit of the set output voltage in the grid linking device 70 that is the second DC power source can be changed within a range in which the priority order does not change during operation of the DC power supply system 3. For example, in the example of FIG. 12, the upper limit of the output voltage can be changed in the range of 264 V or less for the system linkage device 70.

  In the DC power supply system 2 according to the second embodiment and the DC power supply system 3 according to the third embodiment, the second DC power source is only the system linkage device 70. In such a case, in the present invention, the grid linking device 70 considers the highest priority among the second DC power sources and the lowest priority among the second DC power sources.

In the above-described embodiment, the priority assigned to each device 10, 20, 30, 40, 45, 50, 60, 70 is set when the DC power feeding systems 1, 2, 3 are not in operation. The DC power supply systems 1, 2 and 3 cannot be changed while the DC power supply systems 1, 2 and 3 are in operation, but the priority of each device can be changed even when the DC power supply systems 1, 2 and 3 are in operation. Good.
In this case, for example, in the example of FIG. 2, the priorities of the normal power storage device 50 and the grid linking device 70 are the fifth and sixth, but these priorities are switched during the operation of the DC power supply system 1. The priority of the grid connection device 70 can be fifth, and the priority of the normal power storage device 50 can be sixth. As a result, the upper limit of the output voltage of the grid linking device 70 can be set higher than the rated voltage 264V of the normal power storage device 50, and the normal power storage device 50 can be charged with the power supplied from the grid linking device 70. Become.
Further, during the operation of the DC power supply system 1, the priority order of the hydroelectric power generation apparatus 20, the geothermal power generation apparatus 30, and the solar power generation apparatus 40 can be made lower than the priority order of the normal power storage apparatus 50. As a result, only the electric power generated by the wind power generator 10 when the wind is strong can be supplied to the normal power storage device 50 and the load 90.

4, 5, and 6 show examples in which the switch SW is provided on the high potential line LH side for the hydroelectric power generator 20, the geothermal power generator 30, and the solar power generator 40, respectively. Similarly to the power consuming device 80 in FIG. 3, these power generators 20, 30, and 40 may be provided with the switch SW on the low potential line LL side, or on the high potential line LH side and the low potential line LL. It may be provided on both sides.
Moreover, in embodiment mentioned above, although the hydroelectric power generator 20, the geothermal power generator 30, the solar power generation device 40, the grid | linkage linkage apparatus 70, and the power consumption apparatus 80 each showed the example, each of these was shown. The devices may be centrally controlled in their operating state by a common control device.

In each of the above-described embodiments, an example is shown in which the upper limit is not set for the output voltage for the first DC power source with the highest priority, but the upper limit for the output voltage is also set for the first DC power source. It may be set.
For example, in the first embodiment and the third embodiment described above, the upper limit of the output voltage of the wind power generator 10 that is the first DC power source is set to 300 V, and the wind power generator 10 has a voltage of the DC bus 100. Only when the voltage is 300 V or less, a DC voltage may be output to the DC bus 100. In this case, the power consuming device 80 is not necessary. However, when the DC power supply system 1 according to the first embodiment or the DC power supply system 3 according to the third embodiment includes a plurality of wind power generators 10, each wind power generator 10 is provided inside each wind power generator 10. It is necessary to add a device that consumes power when 10 does not output a DC voltage to the DC bus 100.

In the above-described embodiment, an example in which the priority order is determined for each type of each of the devices 10, 20, 30, 40, 45, 50, 60, and 70 has been described. However, a plurality of the same type devices are connected to the DC bus 100. The priority order may be determined among the same type of devices. For example, when a plurality of photovoltaic power generation devices 40 are connected to the DC bus 100, the priority order may be set separately for each photovoltaic power generation device 40.
The wind power generator 10 having the highest priority, the solar power generator 40 having the second priority, the normal power storage device 50 having the third priority, and the grid linking device 70 having the lowest priority. DC power supply system, solar power generation device 45 with the highest priority, normal power storage device 50 with the second priority, system linkage device 70 with the third priority, and the emergency power storage device with the lowest priority 60, the DC power supply system 1 according to the first embodiment, the DC power supply system 2 according to the second embodiment, and the DC power supply system 3 according to the third embodiment. Of course, the present invention can be applied to DC power supply systems having different configurations.
In the first embodiment, the wind power generation device 10, the hydroelectric power generation device 20, and the geothermal power generation device 30 are higher in priority than the solar power generation device 40. However, all of them may have the same priority. That is, the wind power generator 10, the hydroelectric generator 20, the geothermal power generator 30, and the solar power generator 40 may all have the highest priority. In this case, the wind power generator 10, the hydroelectric power generator 20, the geothermal power generator 30, and the solar power generator 40 are the first DC power source of the present invention, and only the system linkage device 70 is the second DC power of the present invention. The source.

As described above, according to the present invention, a plurality of DC power sources connected to a DC bus can be operated according to priority. In particular, in the DC power supply systems 1, 2, and 3 according to the above-described embodiments, the system linkage device 70 has the lowest priority among the DC power sources. When each power generation device using natural energy cannot supply sufficient power to the DC bus 100, the system linkage device 70 supplies power to the DC bus 100 from the AC power system 200. For this reason, it is not necessary to install each power generator using natural energy according to the maximum power consumption of the load 90.
Further, by installing the power consuming device 80, even if each power generating device using natural energy outputs more power than the load 90 consumes, the power consuming device 80 can consume surplus power. For this reason, it is not necessary to control the power generation amount of each power generator by natural energy according to the power consumption of the load 90. In particular, even if the wind power generator outputs a large amount of power during a strong wind, the power consuming device 80 consumes surplus power, so that the wind power generator is electrically braked and there is no possibility of damaging the windmill.
Further, in an emergency, the emergency power storage device 60 supplies power to the DC bus, so that an important device can be operated.

  Although the embodiments of the present invention have been described above, various modifications and combinations necessary for design or manufacturing convenience and other factors are described in the claimed invention and the embodiments of the invention. It is included in the scope of the invention corresponding to the specific example.

DESCRIPTION OF SYMBOLS 1, 2, 3 ... DC power supply system, 10 ... Wind power generator, 20 ... Hydroelectric generator, 21 ... Hydroelectric generator, 22 ... Control part of hydroelectric generator, 30 ... Geothermal power generator, 31 ... Geothermal generator, 32 Control unit of geothermal power generation device, 40, 45 ... Solar power generation device, 41 ... Solar cell array, 42 ... String, 43 ... Control unit of solar power generation device, 50 ... Power storage device, 51 ... Storage battery with rated voltage of 100V, DESCRIPTION OF SYMBOLS 52 ... Protection circuit, 60 ... Emergency power storage device, 61 ... Storage battery of rated voltage 90V, 62 ... Protection circuit, 70 ... System linkage device, 80 ... Power consumption device, 81 ... Resistance element, 82 ... Control part of power consumption device , 90 ... Load, 100 ... DC bus, 200 ... AC power system, SW ... Switch, LH ... High potential line, LL ... Low potential line

Claims (9)

DC bus,
One or more first DC power sources having the highest priority and outputting a DC voltage to the DC bus;
The priority is second or lower, the upper limit of the output voltage is determined according to the priority, and the DC voltage is output to the DC bus when the voltage of the DC bus is lower than the upper limit of the output voltage 1 Two or more second DC power sources;
A direct current power supply system comprising:   The DC power supply system according to claim 1, wherein the second DC power source includes two or more DC power sources having different priorities.   A system in which the second DC power source has the lowest priority among the second DC power sources, and converts an AC voltage supplied from an AC power system into a DC voltage and outputs the DC voltage to the DC bus. The DC power supply system according to claim 1, further comprising a linkage device.   The storage battery of the rated voltage according to the priority order and the charging of the storage battery are stopped when it is determined that the storage battery is overcharged, and the discharge of the storage battery is stopped when it is determined that the storage battery is overdischarged 4. The DC power supply system according to claim 2, wherein the storage battery includes one or more power storage devices connected to the DC bus via the protection circuit.   The DC power feeding system according to claim 4, further comprising the power storage device having a higher priority than the grid linking device.   The DC power feeding system according to claim 5, comprising the power storage device that has a lower priority than the grid connection device. The first DC power source has no upper limit on the output voltage,
When the DC voltage of the DC bus is equal to or higher than a predetermined voltage greater than the upper limit of the output voltage determined for the second DC power source having the highest priority among the second DC power sources, Comprising a power consuming device that consumes power of the DC bus;
The DC power feeding system according to any one of claims 1 to 6, wherein The first DC power source includes one or more wind power generators;
The power consuming device operates as a brake for suppressing or stopping rotation of the wind turbine of the wind turbine generator;
The DC power supply system according to claim 7, wherein The second DC power source includes one or more photovoltaic power generation devices including a solar cell array, the solar cell array including a plurality of strings;
The upper limit of the output voltage is determined for each of the strings according to the priority order,
The DC power feeding system according to any one of claims 1 to 8, wherein

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