JP2015136258A - Power controller, control method for power controller, and power control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently charge a storage battery with power from a power generator, in a power control system adopting a DC link system.SOLUTION: A power controller 100 capable of interconnecting with a system 11 after integrating, in a state of DC power, output power from a plurality of distributed power supplies including first power generators 1a, 1b, a second power generator 1c, and a storage battery 1d includes a switch 4a for selecting whether or not to integrate output power from the first power generators with that from the second power generator. Making the switch 4a be in an off state keeps interconnection between the first power generators and the system as well as performs parallel-off of the second power generator and the storage battery from the system. Processing of charging the storage battery is performed by making the switch 4a be in the off state and charging the storage battery with the output power from the second power generator.

Description

  The present invention relates to a power control apparatus capable of interconnecting a plurality of distributed power sources with a system, a control method for the power control apparatus, and a power control system.

  In recent years, from the viewpoint of improving energy security that does not depend on petroleum and making clean exhaust energy that does not contain nitrogen oxides in the exhaust gas, solar cells that convert solar energy into DC power, and electricity by electrochemical reaction of gas Development of a fuel cell power generation system that generates electricity is underway. For example, Patent Document 1 proposes a fuel cell power supply system using a fuel cell.

  In recent years, in power control systems using distributed power sources such as solar cells and fuel cells, DC link systems that connect the output of each distributed power source with direct current power have been proposed from the viewpoint of easy control and improved efficiency. Has been. This is a system in which power from a solar cell, a fuel cell, etc. is linked as it is DC power, converted into AC power using a single inverter, and supplied to a load. Since there is no need to convert the output for each distributed power supply with an inverter as in the prior art, the system is simplified and the cost can be reduced.

JP-A-7-123609

  Here, in a power control system employing a DC link system, it is conceivable to further connect a storage battery as one of the distributed power sources.

  An object of the present invention made in view of the above point is to provide a method for efficiently charging a storage battery in a power control system including a plurality of distributed power sources.

  In order to solve the above-described problems, a power control device according to the present invention combines output power from a plurality of distributed power sources including a first power generation device, a second power generation device, and a storage battery in a state of DC power. The power control device can be connected to the grid from the power source, and the power control device selects whether to combine the output power of the first power generation device and the output power of the second power generation device By connecting the switch to the off state, the connection between the first power generation device and the system is maintained, and the second power generation device and the storage battery are disconnected from the system. The storage battery is charged by charging the storage battery with the output power of the second power generation device with the switch turned off.

  In addition, in the charging process for the storage battery, the output power of the second power generation device is converted to a predetermined voltage different from the voltage of the DC power when the switch is on. It is preferable to perform from.

  Moreover, it is preferable that the said predetermined voltage corresponds with the voltage of the output electric power of a said 2nd electric power generating apparatus, or the voltage of the input electric power to the said storage battery.

  In addition, the voltage conversion is a first voltage converter for converting a voltage of output power of the second power generator, or a second voltage converter for converting a voltage of input power to the storage battery. It is preferable to carry out using only one of these.

  Moreover, it is preferable that the charging process to the storage battery is performed only when the generated power of the first power generation device is larger than the power consumption of the load connected to the power control device.

  The cost required to generate unit power by the second power generation device is lower than the price for selling the unit power generated by the first power generation device and the price for purchasing unit power from the grid. Is preferred.

  In order to solve the above-described problems, a control method for a power control apparatus according to the present invention is configured to convert output power from a plurality of distributed power sources including a first power generation apparatus, a second power generation apparatus, and a storage battery into direct current power. In the control method of the power control apparatus that can be linked to the grid after being combined in the state, the processing procedure by the power control apparatus maintains the linkage between the first power generation apparatus and the grid. It includes a disconnection step of disconnecting the second power generation device and the storage battery from the system, and a charging step of charging the storage battery with output power of the second power generation device.

  In order to solve the above-described problems, a power control system according to the present invention includes a power control device, and a first power generation device and a second power generation device connected to the power control device. The power control device integrates output power from a plurality of distributed power sources including the first power generation device, the second power generation device, and a storage battery in a state of DC power, and then links to the grid. A switch for selecting whether to combine the output power of the first power generator and the output power of the second power generator, and turning the switch off. Thus, the interconnection between the first power generation device and the system is maintained, and the second power generation device and the storage battery are disconnected from the system, and the charging process for the storage battery is in the off state. As the second The output power of the generator and performs by charging the battery.

  ADVANTAGE OF THE INVENTION According to this invention, in the electric power control system which employ | adopted DC link system, charging to a storage battery from a power generator can be performed efficiently.

1 shows a configuration of a power control system according to an embodiment of the present invention. The relationship between the generated power of the distributed power source in one day and the power consumption in the load is shown. The control flow of the electric power control system which concerns on one Embodiment of this invention is shown. The operation state of the power control system which concerns on one Embodiment of this invention at the time of the power consumption peak of the morning is shown. The operation state (at the time of charge operation) of the electric power control system which concerns on one Embodiment of this invention in case the electric power generated of a solar cell is larger than the power consumption of load is shown. The operation state (at the time of a full charge) of the electric power control system which concerns on one Embodiment of this invention in case the electric power generated of a solar cell is larger than the power consumption of load is shown. The operation state by the self-sustained operation of the power control system according to the embodiment of the present invention at the power consumption peak at night is shown. The operation state by the interconnection | linkage driving | operation of the electric power control system which concerns on one Embodiment of this invention at the time of night power consumption peak is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a power control system 103 according to an embodiment of the present invention. The power control system 103 according to the present embodiment includes a power control apparatus 100 for controlling a distributed power source, a plurality of distributed power sources 1a to 1c, a distribution board 101 for connecting loads, and a plurality of loads 10a to 10a. 10d.

  First, the configuration and operation of the power control apparatus 100 will be described. The power control apparatus 100 includes distributed power supply connection terminals 2a to 2c for connecting the distributed power supplies 1a to 1c, and a voltage for converting DC power input from the distributed power supply connection terminals 2a to 2c into a desired voltage. Bidirectional voltage conversion that converts converters 3a to 3c, storage battery 1d, and output power from storage battery 1d into a desired voltage, or converts DC power from inverter 5 into a desired voltage and supplies it to storage battery 1d 3 d, switches 4 a, 4 b, 6 a to 6 c, an inverter 5, and a control unit 102.

  The distributed power supply connection terminals 2a to 2c are power terminals for inputting / outputting power between the distributed power supplies 1a to 1c and the power control apparatus 100, and the control unit 102 controls the distributed power supplies 1a to 1c. A control signal terminal for performing can be provided. In the present embodiment, a distributed power source 1a (solar cell), a distributed power source 1b (solar cell), and a distributed power source 1c (fuel cell) are connected to the distributed power source connection terminals 2a to 2c, respectively.

  The solar cells 1a and 1b convert the energy of sunlight into DC power. For example, a large number of photoelectric conversion cells are connected in series, and are configured to output a predetermined current when irradiated with sunlight. . In the present embodiment, for example, silicon-based polycrystalline solar cells can be used for the solar cells 1a and 1b connected to the distributed power connection terminals 2a and 2b, but the present invention is not limited thereto. Any silicon-based single crystal solar cell or thin film solar cell such as CIGS may be used as long as it is capable of photoelectric conversion.

  The fuel cell 1c generates electricity by gas electrochemical reaction, and can be classified according to the type of electrolyte used, reaction temperature, and the like. Low temperature types with a reaction temperature of 300 ° C or less include solid polymer type (PEFC) and phosphoric acid type (PAFC). High temperature types include molten carbonate type (MCFC) and solid oxide type (SOFC). and so on. Among them, the solid oxide form is characterized in that exhaust heat is easy to use because of the high operating temperature, and high power generation efficiency is obtained. In this embodiment as well, this solid oxide form (SOFC) fuel A battery can be used.

  The storage battery 1d is preferably a lithium ion battery, for example, but other types of storage batteries such as nickel metal hydride batteries can also be used. In addition to a single storage battery, it is also possible to charge a storage battery mounted on an electric vehicle (EV) or a plug-in hybrid vehicle (PHV).

  The voltage converters 3a to 3d perform DC / DC conversion so that the DC output voltages of the respective distributed power supplies 1a to 1d have predetermined DC voltage values. More specifically, the voltage converters 3a to 3d have DC / DC conversion circuits, and based on control signals from the control unit 102, DC input voltages from the respective distributed power sources 1a to 1d are converted into predetermined target voltages. The voltage is boosted to a value and then output to the inverter 5.

  Further, the voltage converters 3c and 3d can perform bidirectional DC / DC conversion, and step up or step down the DC output power from the fuel cell 1c and the storage battery 1d and output it to the inverter 5. The DC input power from the other voltage converters 3a and 3b can be stepped down or boosted and supplied to the fuel cell 1c and the storage battery 1d. Further, the DC output power from the fuel cell 1c can be stepped up or stepped down by the voltage converter 3c, and further stepped down or stepped up by the voltage converter 3d and supplied to the storage battery 1d.

  As described above, it is necessary to supply power to the fuel cell 1c from the outside. For example, when the fuel cell 1c is a solid oxide fuel cell, it takes a long time to supply power from the outside. This is because if the cooling is not performed, the brittle ceramic power generation cell may be cracked.

  The distributed power sources 1a to 1c connected to the distributed power source connection terminals 2a to 2c have different DC input voltages from each other, but in the present embodiment, the voltage converters 3a to 3c are different according to each DC input voltage. By performing voltage conversion with the adjustment amount, the voltage is boosted to the same target voltage value.

  The distributed power sources 1a and 1b connected to the distributed power source connection terminals 2a and 2b may rectify and output AC power, such as a wind power generator or a small hydraulic power generator, in addition to a solar battery.

  The DC link switch 4a is a switch for selecting whether or not to DC link the output power of the solar cells 1a and 1b and the output power of the fuel cell 1c. The DC link switch 4a is configured by a relay, a transistor, and the like, and is configured to switch the on / off state based on a control signal from the control unit 102. When the DC link switch 4a is in the ON state, the output power of the distributed power sources 1a to 1d having different output voltages is stepped up or down to the same DC link voltage by the voltage converters 3a to 3d. The output powers of the distributed power sources 1 a to 1 d that have been converted into the DC link voltage are collected and input to the inverter 5.

  On the other hand, when the DC link switch 4a is in the off state, the output power from the solar cells 1a and 1b and the output power from the fuel cell 1c are not collected but supplied to separate functional blocks. That is, when the DC link switch 4a is in the OFF state, the output power from the solar cells 1a and 1b is sent to the loads 10a to 10d via the inverter 5, the switches 6a and 6b or the switch 6c, and the distribution board 101. Supplied. The output power from the fuel cell 1c is converted into a predetermined voltage suitable for charging by the voltage converter 3c or 3d, and then charged to the storage battery 1d.

  The switch 4b is a switch for selecting whether to short-circuit both ends of the voltage converter 3d. By turning on the switch 4b and stopping the voltage converter 3d, for example, DC power generated by the fuel cell 1c and voltage-converted by the voltage converter 3c can be charged into the storage battery 1d without further conversion. .

  The inverter 5 converts the power after voltage conversion from each of the distributed power sources 1a to 1d into power corresponding to the loads 10a to 10d based on a control signal from the control unit 102. In the present embodiment, the inverter 5 converts the power after voltage conversion from each of the distributed power sources 1a to 1d into AC 100V. The electric power converted into AC 100V is supplied to loads 10a to 10d connected to the distribution board 101 via the switches 6a and 6b or the switch 6c.

  The switches 6a to 6c are an interconnection switch, a system bypass switch, and a self-supporting switch, respectively. The switches 6a to 6c are configured by relays, transistors, and the like, and are configured to switch on / off states based on a control signal from the control unit 102.

  The interconnection switch 6 a is a switch that switches on / off of interconnection between the distributed power supply and the system 11. That is, when the interconnection switch 6a is on, the outputs of the distributed power sources are collectively connected to the system 11. When the interconnection switch 6a is off, the outputs of the solar cells 1a, 1b, the fuel cell 1c, and the storage battery 1d are all disconnected from the system 11, and the output of the distributed power supply is not connected to the system 11.

  The system bypass switch 6b is a switch for closing a path for supplying the output of the system 11 and / or the distributed power source to the load when the distributed power source is connected to the system 11.

  The self-supporting switch 6c is a switch that closes a path for supplying the output of the distributed power source to the load when the distributed power source is not linked to the system 11. That is, the self-supporting switch 6c is turned on when the interconnection switch 6a is in the off-state, and when the distributed power supply is disconnected from the system 11, the output of the distributed power supply is supplied to the load to be operated independently. The system bypass switch 6b is turned off during such a self-sustained operation, and the system bypass switch 6b is turned on except during the self-sustained operation.

  Next, the configuration and operation of the distribution board 101 will be described. The distribution board 101 includes a current sensor 7, a service breaker 8, and breakers 9a to 9e. The service breaker 8 is arranged between the power control device 100 and the system 11 when a plurality of distributed power sources are connected to the system 11 together. For example, during the forward power flow, the service breaker 8 generates power exceeding the contracted capacity. Cut off. The breakers 9a to 9e are safety breakers arranged at locations where power is branched from the distribution board 101 to various loads such as in the home. Electric power is supplied to the load from each of the breakers 9a to 9e. These breakers 9a to 9e cut off the electric power when a short circuit occurs due to a failure of an electric appliance and a cable in each room of the home or when an overcurrent flows. In addition, although the distribution board 101 may be provided with various function parts, such as an earth-leakage breaker, the description about the detail of such a function part is abbreviate | omitted.

  The current sensor 7 detects the power output from the power control apparatus 100 side through the distribution board 101 to the system 11 side, that is, the power that is obtained by collecting the outputs of the distributed power sources and flows backward to the system. The current sensor 7 can be configured by an arbitrary current sensor such as a CT (Current Transformer). In this way, the result detected by the current sensor 7 is notified to the control unit 102. Therefore, the control unit 102 can recognize the detection result of the current sensor 7. For example, when the current sensor 7 detects a reverse power flow, control can be performed so that the fuel cell 1 c is disconnected from the system 11. it can. In the present embodiment, the current sensor 7 is disposed in the distribution board 101, but may be disposed in the power control apparatus 100, for example.

  Some fuel cells include a current sensor. A fuel cell equipped with such a current sensor may be designed to generate power only when the current sensor detects a forward current with respect to a load. When a fuel cell having such a specification is employed in the power control system of the present invention, a current sensor can be installed as the current sensor 7 shown in FIG. 1, and the detection result of the current sensor 7 can be notified to the fuel cell 1c.

  The distribution board 101 is connected to loads 10 a to 10 d that operate at 100 V AC. Examples of loads that operate at AC 100 V include refrigerators, emergency lights, hot water supply systems, home network servers, and other electrical products that should avoid power outages as much as possible, as well as dryers, home game consoles, audio systems for listening to music, etc. General household load.

  In the present embodiment, the path of the control signal for the control unit 102 to control each component is indicated by a broken line in FIG. 1, but this control signal may be transmitted by wired communication or wirelessly. Communication may be used.

  The control unit 102 may be configured by hardware, or a function may be realized by causing a CPU to execute a program.

  Although it has been described that the voltage converters 3a to 3d and the inverter 5 in the present embodiment control the output voltage by the control unit 102, the present invention is not limited to this and is set up to have a predetermined output voltage. It may be.

  In this embodiment, the AC power output is configured to output a single-phase AC 100V to the loads 10a to 10d, but a three-phase three-wire 200V is often used for a commercial refrigerator or air conditioner, motor drive in a factory, and the like. In order to be used, instead of the inverter 5, an inverter 5 ′ for converting into three-phase 200V may be arranged.

  In the present embodiment, the load to be connected is described assuming an electric device that can be used in Japan. However, the load can be appropriately changed in consideration of the use of an electric device that can be used outside of Japan. For example, the inverter 5 can output AC 220 to 240 V, and can be configured to be connectable to electrical equipment that can be used in Asia, Oceania, and Europe.

  Next, the operation of the power control system 103 according to an embodiment of the present invention will be described. In the present embodiment, the power generated by each distributed power source (solar cells 1a, 1b and fuel cell 1c) in one day and the power consumption of the load draw a curve as shown in FIG. First, the fuel cell performs rated operation throughout the day and always generates constant power regardless of time. It is assumed that the solar battery reaches the peak of generated power after noon (time C), and the generated power at the peak time sufficiently exceeds the power consumption of the load. On the other hand, at the peak of power consumption in the morning and evening (time A and F), even if the total power generated by the solar cell and the fuel cell is summed, the power consumption of the load is not exceeded.

  FIG. 3 shows a control flow of the power control system 103 according to an embodiment of the present invention. The control unit 102 determines whether or not the generated power in the solar cells 1a and 1b is larger than the power consumption of the load (S301), and whether or not charging from the fuel cell 1c to the storage battery 1d is necessary (S302), Based on those results, the DC link switch 4a and the like are controlled. In the present embodiment, the cost required to generate unit power by the fuel cell 1c is lower than the price for selling the unit power generated by the solar cells 1a and 1b and the price for purchasing unit power from the grid 11. Will be described.

(At peak power consumption in the morning)
In the morning power consumption peak time (shown at time A) in FIG. 2, the control unit 102 determines whether or not power can be supplied to the load by power generation by the solar cell in the control flow of FIG. 3 (S301). Since the generated power is insufficient, the operation is performed to supply the shortage of power generation by the solar cells 1a and 1b from the fuel cell 1c and, if necessary, the storage battery 1d (S308). That is, the control unit 102 maintains the switch 4a in the on state, DC-links the generated power from the fuel cell 1c and the storage battery 1d in addition to the generated power from the solar cells 1a and 1b, and inputs the DC link to the inverter 5. In addition, the control unit 102 performs control so that the interconnection switch 6a and the system bypass switch 6b are in the off state and the independent switch 6c is in the on state, so that the autonomous operation is performed. In this case, the shortage in the solar battery may be supplied from the grid 11 by connecting the grid switch 6a and the grid bypass switch 6b to the on state and the self-supporting switch 6c to the off state to link to the grid 11. However, since the cost required for the fuel cell 1c to generate unit power as described above is lower than the price for purchasing unit power from the grid 11, it is preferable to supply power from the distributed power source to the load by independent operation. . The operation state of the power control system 103 at this time is shown in FIG.

(When the power generated by the solar cell is greater than the power consumption of the load)
In FIG. 2, when the generated power of the solar cell becomes larger than the power consumption of the load (between times B and E), the control unit 102 determines whether or not the solar cell can supply power to the load in the control flow of FIG. Since the generated power in the solar cells 1a and 1b exceeds the power consumption in the load, it is next determined whether or not the storage battery 1d needs to be charged (S302). When a constant power is consumed at night and the storage battery is not fully charged at time B, the control unit 102 turns off the DC link switch 4a (S303) and stops the voltage converter 3d (S304). 4b is turned on to short-circuit both ends of the voltage converter 3d. In the present embodiment, the voltage converter 3d directly connected to the storage battery 1d is stopped and both ends thereof are short-circuited. However, the voltage converter 3c connected to the fuel cell 1c is stopped. You may comprise so that the both ends may be short-circuited. In such a configuration, the voltage of the output power of the fuel cell 1c is directly input to the voltage converter 3d, and after voltage conversion, the storage battery 1d is charged.

  Next, the control unit 102 sets the step-up ratio in the voltage converter 3c to a value suitable for charging the storage battery (S305). For example, assuming that the output voltage of the fuel cell 1c is 160V DC and the input voltage optimum for charging the storage battery 1d is 190V, the control unit 102 sets the boost ratio in the voltage converter 3c to 190/160 = 1. Set to 19.

  When the setting of the voltage converter 3c is completed, the control unit 102 starts charging from the fuel cell 1c to the storage battery 1d and starts supplying power from the solar cells 1a and 1b to the loads 10a to 10d (S306). At this time, the interconnection switch 6a and the system bypass switch 6b are turned on, and the self-supporting switch 6c is turned off to connect to the system 11. Thereby, for example, when the generated power in the solar battery at time C in FIG. 2 greatly exceeds the power consumption in the load, the surplus of the generated power in the solar battery can be sold through the system 11. The operating state of the power control system 103 at this time is shown in FIG. Charging from the fuel cell 1c to the storage battery 1d continues until the storage battery is fully charged (until time D in FIG. 2).

  On the other hand, in step S302, when the storage battery 1d is in a fully charged state and charging is not necessary, the control unit 102 turns on the DC link switch 4a as shown in FIG. 6 to turn on the solar cells 1a and 1b and the fuel cell. The generated power of 1c is supplied to the loads 10a to 10d, and surplus power of the solar cells 1a, 1b and the fuel cell 1c is caused to flow backward to the grid 11 and sold. If it is not permitted to reversely flow the generated power from the fuel cell 1c to the grid 11, the DC link switch 4a is turned off in FIG. 6, and only the surplus power of the solar cells 1a and 1b is fed to the grid 11 You may make it flow backward.

(Night power consumption peak)
In the case of the nighttime power consumption peak time of FIG. 2 (indicated by time F), the control unit 102 determines whether or not power can be supplied to the load by power generation by the solar cell in the control flow of FIG. 3 (S301). ) Since there is no power generation by the solar cell and the generated power is insufficient, the operation is performed to supply the shortage of the solar cell power generation from the fuel cell 1c and, if necessary, the storage battery 1d (S308). That is, the control unit 102 maintains the switch 4a in the on state, and causes the inverter 5 to input the generated power from the fuel cell 1c and the storage battery 1d. In addition, the control unit 102 performs control so that the interconnection switch 6a and the system bypass switch 6b are in the off state and the independent switch 6c is in the on state, so that the autonomous operation is performed. The operating state of the power control system 103 at this time is shown in FIG. In addition, since there is no power generation from the solar cells 1a and 1b at the time of the power consumption peak at night, when the power consumption in the load greatly exceeds the power generation in the fuel cell 1c, as shown in FIG. The shortage of generated power in the fuel cell may be supplied from the grid 11 by connecting the grid 6 to the grid 11 with the 6a and the grid bypass switch 6b turned on and the self-supporting switch 6c turned off.

  As described above, according to an embodiment of the present invention, in a power control system that supplies a plurality of distributed power sources to a load or the like by DC linking, when charging a storage battery from a fuel cell, Since the configuration is such that the power generated by the solar cell is disconnected, there is no need to boost the output voltage of the fuel cell to a normal DC link voltage, and it can be set to an optimum voltage for charging the storage battery.

  According to one embodiment of the present invention, only one voltage converter needs to be operated in the path from the fuel cell to the storage battery, and the conversion efficiency at the time of voltage conversion can be improved.

  Further, according to one embodiment of the present invention, power is not supplied as much as possible from the system, and charging to the storage battery 1d is preferentially supplied with power from the fuel cell 1c, and the generated power of the solar cells 1a and 1b is Since it is configured to sell as much as possible, the cost required to generate unit power by the fuel cell 1c is less than the price for selling unit power generated by the solar cells 1a and 1b and the price for purchasing unit power from the grid 11. If it is low, the power generation cost as a whole can be suppressed.

  In the embodiment of the present invention, the case where the solar cells 1a and 1b are used as the first power generation device capable of reverse flow has been described. However, in the present invention, the first power generation device is not limited to a solar battery, and a distributed power source that performs power generation other than solar power generation, such as wind power generation, is adopted as long as it can reversely flow. You can also.

  In the power control system described above, a power distribution board dedicated to the power control apparatus 100 may be further provided between the power control apparatus 100 and the power distribution board 101. Thus, providing a dedicated distribution board contributes to the maintenance of the power control apparatus 100 when it fails or is repaired.

  In the embodiment of the present invention, the power control apparatus that integrates the output of the distributed power source as DC power and is linked to the grid 11 has been described. However, the present invention is not limited to the one in which the output of the distributed power source is DC power, and an AC power source can also be employed.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, the functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined into one or divided. Is possible.

1a, 1b Solar cell (first power generator)
1c Fuel cell (second power generator)
1d storage battery 2a-2c distributed power supply connection terminal 3a-3d voltage converter 4a, 4b switch 5 inverter 6a-6c switch 7 current sensor 8 service breaker 9a-9e breaker 10a-10d load 11 system 100 power control device 101 distribution board 102 Control unit 103 Power control system

Claims (8)

A power control device capable of interconnecting with a system after collecting output power from a plurality of distributed power sources including a first power generation device, a second power generation device, and a storage battery in a state of DC power,
The power control device has a switch for selecting whether to combine the output power of the first power generation device and the output power of the second power generation device,
By turning off the switch, the connection between the first power generation device and the system is maintained, and the second power generation device and the storage battery are disconnected from the system,
The charging process for the storage battery is performed by charging the output power of the second power generation apparatus to the storage battery with the switch turned off.   The charging process to the storage battery is performed after converting the output power of the second power generation device to a predetermined voltage different from the voltage of the DC power when the switch is on. The power control apparatus according to claim 1.   The power control device according to claim 2, wherein the predetermined voltage matches a voltage of output power of the second power generation device or a voltage of input power to the storage battery.   The voltage conversion is either a first voltage converter for converting the voltage of the output power of the second power generator or a second voltage converter for converting the voltage of the input power to the storage battery. The power control apparatus according to claim 2, wherein the power control apparatus is performed using only one of them.   The charging process to the storage battery is performed only when the generated power of the first power generation device is larger than the power consumption of a load connected to the power control device. The power control apparatus described.   The cost required for generating unit power by the second power generation device is lower than a price for selling unit power generated by the first power generation device and a price for purchasing unit power from the grid. The power control apparatus according to any one of 1 to 5. A control method for a power control apparatus capable of connecting output power from a plurality of distributed power sources including a first power generation apparatus, a second power generation apparatus, and a storage battery in a DC power state and then interconnecting with a system. The processing procedure by the power control device is as follows:
A disconnection step of maintaining the connection between the first power generation device and the system and disconnecting the second power generation device and the storage battery from the system;
And a charging step of charging the storage battery with the output power of the second power generation device. A power control system comprising a power control device, a first power generation device and a second power generation device connected to the power control device,
The power control device can link the output power from a plurality of distributed power sources including the first power generation device, the second power generation device, and the storage battery in a state of DC power and then link to the system. A switch for selecting whether to combine the output power of the first power generator and the output power of the second power generator;
By turning off the switch, the connection between the first power generation device and the system is maintained, and the second power generation device and the storage battery are disconnected from the system,
The charging process for the storage battery is performed by charging the output power of the second power generation device to the storage battery with the switch turned off.

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