JP2019030152A - Power control system and power control method - Google Patents

Abstract

To provide a system and a method, capable of improving energy efficiency by reducing reception electric energy even when a set value is not reached.SOLUTION: This system includes: measurement means for measuring reception electric energy; control means for outputting an activation command depending on the measured reception electric energy and a set condition; power generation means that is activated by receiving the activation command; switching means for receiving power supply from the power generation means and switching power to be supplied to a specific power load from the reception power to power generated by the power generation means; and hot-water supply means that is activated using the generated power, heats water using exhaust gas discharged from the power generation means, and supplies hot water to a hot water supply load.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power control system and method for controlling power.

  A demand controller is used as a device for suppressing the amount of commercial power used (amount of received power). The demand controller is a device that monitors the amount of received power and performs automatic control such as reducing the output of a device (power load) that consumes power or consumes power so as not to exceed a set value.

  As a technique using a demand controller, a technique is known that compensates for a decrease in the capacity of an air conditioner caused by a demand controller by adjusting the output of a backup energy generator (see Patent Document 1).

  When the amount of received power (received demand) reaches the demand threshold, power is generated by the power generation means, and the generated power is supplied to the load. During that time, the generated power is measured and added to the received demand, and the total value is used as the load demand. A technique is known in which the power generation of the power generation means is stopped when the load demand is less than the demand threshold (see Patent Document 2).

JP-A-9-285011 JP 2008-86163 A

  However, in the above-described conventional technology, when the amount of received power does not reach the set value, no power is supplied from the power generation device, and exhaust heat is not recovered, so that the amount of received power is reduced and energy efficiency is improved. It could not be improved.

  Thus, it has been desired to provide a system and method that can reduce the amount of received power and improve the energy efficiency even when the amount of received power has not reached the set value.

In view of the above problems, the present invention is a power control system for controlling power,
A measuring means for measuring the amount of received power;
Control means for outputting a start command according to the amount of received power measured by the measuring means and the set condition;
Power generation means that starts in response to a start command from the control means;
Switching means for receiving power supply from the power generation means and switching the power supplied to the specific power load from the received power to the generated power of the power generation means;
A power control system is provided that includes hot water supply means that operates by the generated power switched by the switching means, heats water with exhaust gas discharged from the power generation means, and supplies hot water to a hot water supply load.

  According to the present invention, even when the amount of received power does not reach the set value, the amount of received power can be reduced and the energy efficiency can be improved.

The figure which showed the structural example of the electric power control system. The figure which showed the structural example of the demand controller. The figure explaining operation | movement of the switch with which a load power supply switching board is provided. The figure explaining the control at the time of linked operation. The figure explaining the control at the time of independent operation. The flowchart which showed the flow of the process performed by an electric power control system.

  FIG. 1 is a diagram illustrating a configuration example of a power control system. The power control system is a commercial power supplied from a power system to a power receiving facility of a consumer, a power generated by the photovoltaic power generation panel 10, and a stored power of a storage battery 11 used as a power storage means, a cogeneration system (hereinafter referred to as a power generation means). This is a system that controls electric power such as generated electric power generated by 12. The power system is a power system including all of power generation equipment, substation equipment, power transmission equipment, and power distribution equipment, and consumers are buildings, houses, hospitals, schools, stores, factories, and the like that consume power.

  The power control system is supplied with commercial power and the stored power of the storage battery 11. The stored power of the storage battery 11 may be supplied to the power control system together with the commercial power after power storage, or may be supplied during a power failure. Here, it is assumed that the stored power of the storage battery 11 is supplied at the time of a power failure, and that commercial power is received as received power.

  The power control system is connected to a plurality of power loads that consume power and are supply destinations for supplying power. The electric power load includes an electric light load 13 such as lighting, a specific electric power load (specific electric power load) 14 such as an air conditioner and an external air conditioner, a power load 15 such as a motor and a pump, and the like. The specific power load 14 is a device or facility set as a power load to be supplied by the system administrator without being cut off.

  The photovoltaic power generation panel 10 receives sunlight and generates a plurality of solar cell modules that generate DC power, a junction box that collects DC power generated by the plurality of solar cell modules, and a backflow prevention for preventing backflow A diode. The photovoltaic power generation panel 10 is connected to the storage battery 11 via a converter (power conditioner) 16 for converting DC power to AC power, and the storage battery 11 stores AC power.

  In the power generation by the photovoltaic power generation panel 10, it is possible to operate in parallel with the commercial power by system linkage, and it is possible to supply surplus power to the power system (reverse tide) and purchase power. In consideration of an emergency, a configuration in which power is stored in the storage battery 11 is adopted, so that there can be no reverse tide.

  The power control system includes a cogeneration 12. The cogeneration 12 is an energy supply system that generates electric power by driving a generator with an engine and uses exhaust heat of the engine to improve overall energy efficiency. The cogeneration unit 12 can include a converter that temporarily converts the generated power generated by the generator into direct current, and an inverter that converts the direct current into alternating current with a voltage and frequency equal to commercial power. In addition, the cogeneration 12 can include a storage battery that stores electric power required for starting up, a measuring instrument that measures the amount of electric power generated, and the like.

  The power control system connects the storage battery 11 and a power system that supplies commercial power, branches and supplies power to a power receiving / transforming cubicle 17 that transforms to a low voltage used by consumers, and to a light load 13 and a power load 15. And a specific load power lamp board 18 for performing.

  The power receiving / transforming cubicle 17 includes a transformer and measuring equipment as measuring means for measuring the amount of received power. The transformer transforms to the low voltage used by the above-mentioned consumer. The power receiving and transforming cubicle 17 is a switch that switches a power receiving path so as to receive the power of the storage battery 11 when receiving of commercial power is stopped due to a power failure or the like, or a specific load power lamp that becomes a secondary side due to overload or short circuit A breaker or the like is also provided as a blocking means for opening the electric circuit when an abnormal current flows through the panel 18 or the like and cutting off the power supply from the primary side.

  The specific load power lamp board 18 supplies three-phase AC power used by the power load 15 and supplies single-phase AC power used by the lamp load 13. The specific load power lamp board 18 also includes a breaker as a shut-off means that opens the electric circuit when an abnormal current flows through the lamp load 13 or the power load 15 on the secondary side and cuts off the power supply from the primary side. . Moreover, the specific load power lighting board 18 can include a transformer (Scott transformer) that converts three-phase AC power into single-phase AC power. Note that the Scott transformer does not have to be included in the specific load power lamp board 18 and is provided between the specific load power lamp board 18 and the lamp load 13 and is supplied from the specific load power lamp board 18. You may convert alternating current power into single phase alternating current power.

  The power control system is provided between the receiving / transforming cubicle 17 and the cogeneration 12, monitors the amount of received power measured by the measuring device, and sets the value (first threshold) set as the management target value of the received power. Based on this, a demand controller 19 is included as a control means for controlling electric power. The demand controller 19 monitors the constantly changing power consumption by measuring the amount of received power, and activates the cogeneration 12 when the average value of the commercial power in a certain period exceeds the first threshold value. The power is generated and the average value is controlled to be less than the first threshold value. Generally, the average value of commercial power in a certain period is average power (demand power) for 30 minutes, and this demand power is called demand.

  In order to control the amount of commercial power, the demand controller 19 outputs a start command to the cogeneration 12 and supplies the generated power generated by the cogeneration 12 to the specific power load 14. As a result, the commercial power supplied to the specific power load 14 is replaced with the generated power of the cogeneration 12, so that the amount of received power can be reduced below the first threshold.

  The demand controller 19 also monitors the amount of received power and the amount of generated power that the cogeneration 12 supplies to the specific power load 14, and the sum of the amount of received power and the amount of generated power is less than the first threshold. If it is less than the first threshold, even if it is returned to the commercial power, it will be less than the first threshold, so a stop command can be output to the cogeneration 12.

  Further, the demand controller 19 stores the measured amount of received power as demand data, manages the amount of power received in one day as daily report data, manages the amount of power received in one month as monthly report data, USB communication, SD Data can be output to the outside of a PC or the like by a card or the like. In a PC or the like, data can be received or read from an SD card, and the demand trend can be displayed as a demand load curve, a monthly demand trend, an annual demand trend, or the like.

  Here, the configuration of the demand controller 19 will be described with reference to FIG. The demand controller 19 includes a CPU 30 that executes the above control, a ROM 31 that stores a program executed by the CPU 30, and a RAM 32 that provides a work area to the CPU 30. The demand controller 19 is equipped with a connection I / F 33 for connecting to an external device such as a PC, a storage medium 34 such as an SD card, and a storage medium 34 to enable the above USB communication. And a storage control I / F 35 for controlling writing to the storage.

  In addition, the demand controller 19 includes a network I / F for connecting to a network such as a LAN, a display unit 36 for displaying a measurement error, an operation unit 37 such as an operation switch, a storage battery for supplying power in the event of a power failure, and the like. Can be provided.

  Referring again to FIG. 1, the power control system operates by receiving the power generated by the cogeneration 12, heats water with the high-temperature exhaust gas discharged from the cogeneration 12, and supplies hot water to the hot water supply load 20. Means. The hot water supply means includes a heat exchanger 21 that exchanges heat between exhaust gas and water, a hot water tank 22 that receives and stores hot water that is supplied with water, and a fan or blower as a suction means that sucks exhaust gas. 23, the water staying at the bottom of the hot water storage tank 22 is sucked, supplied to the heat exchanger 21, the circulation pump 24 as a circulation means for returning to the hot water storage tank 22 after heat exchange, and hot water near the water surface of the hot water storage tank 22. And a hot water supply pump 25 as hot water supply means for supplying to the hot water supply load 20.

  The water in the hot water storage tank 22 is circulated by the circulation pump 24 and is heat-exchanged with the high-temperature exhaust heat by the heat exchanger 21, so that it is gradually heated and becomes hot water having a predetermined temperature. When the temperature of the hot water in the hot water tank 22 reaches a predetermined temperature, the hot water supply pump 25 can be activated to supply hot water.

  The power control system receives the supply of generated power from the cogeneration 12 and loads the power supply switching board 26 as a switching means for switching the power supplied to the specific power load 14 from the commercial power to the generated power. And a specific load power board 27 that branches and supplies electric power to each. The commercial power supplied to the load power switching board 26 is supplied from the power receiving / transforming cubicle 17 via the power board 28.

  The specific load power board 27 includes a plurality of breakers, each power load is connected to each breaker, and supplies the power from the load power source switching board 26 to each power load through each breaker. The power board 28 includes a breaker, and the load power source switching board 26 is connected to the breaker, and supplies power from the power receiving / transforming cubicle 17 to the load power source switching board 26 through the breaker.

  The load power supply switching board 26 performs switching in response to the supply of switching power from the cogeneration 12. The switching power source is generated by the cogeneration unit 12 when the cogeneration unit 12 receives an activation command from the demand controller 19 and is output to the load power source switching panel 26. The load power supply switching board 26 includes a switch 29 for switching between the commercial power and the generated power of the cogeneration 12 with respect to the specific power load 14, and the switch 29 switches from the commercial power to the generated power or from the generated power to the commercial power. Can do.

  The load power switching board 26 may directly switch the commercial power to the power generated by the cogeneration 12, but is connected to the cogeneration 12 while maintaining the supply of the commercial power to the specific power load 14. , The supply of commercial power to the specific power load 14 can be stopped. For example, the load power source switching panel 26 includes two connecting portions connectable to each of two terminals as shown in FIG. 3A, and is connected to the power panel 28 as shown in FIG. While maintaining the connection, it is connected to the cogeneration 12, temporarily receives commercial power and power from the cogeneration 12, disconnects from the power panel 28 as shown in FIG. 3C, and connects to the cogeneration 12. Can only be. By doing in this way, the fluctuation | variation of the electric power accompanying switching can be suppressed.

  The switch 29 may have a configuration in which two connection portions are connected to one terminal after switching, or a partition portion is provided in the center of the two terminals, and only one connection portion is connected to one terminal. The structure which cannot be used may be sufficient.

  Referring to FIG. 1 again, the demand controller 19 controls the received power amount so as not to exceed the first threshold, and may output a start command to the cogeneration 12 according to the set condition. it can. The condition is, for example, a period when there is a large demand for hot water supply and a time period before the evening when consumption increases, specifically, from Monday to Friday from December to March from 1 pm to 3 pm Can be set. In addition, since this period is an example, it is not restricted to this. By setting such conditions, even if the amount of received power is less than the first threshold, during the period, the cogeneration 12 is activated, the amount of received power is reduced, and exhaust heat recovery is performed to reduce energy. Efficiency can be improved.

  In this case, the demand controller 19 can output a start command at the start of the period. Further, the demand controller 19 can output a stop command to the cogeneration 12 at the end of the period. The condition is not limited to the period, and may be, for example, the temperature. In this case, a thermometer is provided, and the demand controller 19 can monitor the temperature measured by the thermometer.

  Further, the demand controller 19 can output an activation command to the cogeneration 12 according to whether there is a power failure. At the time of a power failure, the commercial power is cut off, the supply of power from the storage battery 11 is started, and the power is continuously supplied to the lamp load 13 and the specific power load 14, but the power load 15 is stopped. The amount of received power that is measured at is reduced. Therefore, the demand controller 19 can determine that the demand controller 19 is a power failure and can output an activation command to the cogeneration 12 when the amount of received power is less than a certain amount of power (second threshold). The second threshold is a value smaller than the first threshold. Thereby, even when a power failure occurs, a necessary amount of power can be supplied to the specific power load 14 without reducing the output.

  The demand controller 19 can control the power of the storage battery 11 to be supplied to the lamp load 13 when it is determined that there is a power failure. In addition, the demand controller 19 may supply the electric power to the lamp load 13 at the time of a power failure from the storage battery 11, may switch after the cogeneration 12 starts, and may supply from the cogeneration 12.

  When the demand controller 19 is provided with a storage battery, when the power supply to the demand controller 19 is switched from commercial power to its own storage battery, or when switching from commercial power to the storage battery, the demand controller 19 is less than the second threshold value. It is also possible to determine that there is a power failure and output a start command to the cogeneration 12.

  In addition, when power is supplied from commercial power, the demand controller 19 starts power supply to the lamp load 13 and the power load 15, and thus determines whether or not the second threshold value is exceeded. In the above case, it can be determined that the power has recovered from the power failure, and a stop command can be output to the cogeneration 12.

  In the example shown in FIG. 1, the switch 29 is a switch that switches between commercial power and generated power. However, the switch 29 is not limited to this, and is, for example, a switch that switches between both commercial power and generated power and generated power. May be. By adopting such a configuration, it is possible to perform a linked operation and a self-sustained operation, and it is possible to provide a system that is normally set to a linked operation, and that can be operated as a self-sustained operation at the time of a power failure, and can cope with a power failure.

  Here, with reference to FIG. 4, the linked operation and the control during the linked operation will be described. The power control system receives commercial power when the amount of received power is equal to or greater than the first threshold or when the above conditions are met, and simultaneously activates the cogeneration 12 to generate power. Supply generated power. The linked operation refers to generating power by the cogeneration 12 in parallel with receiving commercial power in this way.

  The power control system includes a cogeneration 12, a power receiving / transforming cubicle 17, a specific load power lamp 18, a demand controller 19, and a load power switching board 26, and starts the cogeneration 12 according to a start command from the demand controller 19. The cogeneration 12 includes an engine 40 and a generator 41. The engine 40 burns gaseous fuel such as natural gas or liquefied propane (LP) gas to generate thermal energy, and converts the thermal energy into kinetic energy. The generator 41 converts kinetic energy from the engine 40 into electrical energy and outputs it as electric power. The heat energy that has not been used for conversion into kinetic energy by the engine 40 is recovered by the heat exchanger 21 as exhaust heat.

  The commercial power passes through the power receiving / transforming cubicle 17 and the specific load power lamp board 18 in order, and merges with the generated power output from the generator 41 of the cogeneration 12, so that the combined power can be supplied to the specific power load 14. Turn on the switch 42 on the linked operation side.

  In FIG. 4, the linked operation side is a connection terminal on the right side of the switch 42, and can be controlled to perform linked operation by connecting to the connection terminal. In FIG. 4, the switch 42 on the linkage operation side is turned on to supply both commercial power and generated power. However, when the amount of received power is less than the threshold, if the above conditions are not met, only the commercial power is supplied. Therefore, the operation of the cogeneration 12 can be stopped with the switch 42 on the linked operation side kept ON.

  The specific load power board 27 includes a plurality of breakers 43, the specific power load 14 includes a plurality of power loads 44 set by a system administrator, and each power load 44 is connected to each breaker 43, and Since the switch 42 on the linked operation side is ON, both commercial power and generated power are supplied.

  With reference to FIG. 5, the independent operation and the control during the independent operation will be described. Since the power control system cannot supply commercial power when a power failure occurs, only the cogeneration 12 is operated and the generated power of the cogeneration 12 is supplied. Independent operation refers to driving only such cogeneration 12.

  In this case, it is possible to switch to the operation of only the cogeneration 12 by switching the connection to the connection terminal on the left side of the switch 42 instead of the linked operation side and turning on the switch 42 on the independent operation side. When returning from a power failure, the switch 42 on the linked operation side can be turned on again.

  In the self-sustained operation, only the generated power of the cogeneration 12 is supplied to the plurality of power loads 44 in the specific power load 14.

  With reference to FIG. 6, the process which a power control system performs is demonstrated. The power control system stores the power generated by the photovoltaic power generation panel 10 in the daytime in the storage battery 11 via the power conditioner 16 and receives the supply of commercial power, and the lamp load 13, the specific power load 14, the power Commercial power is supplied to the load 15. At night, commercial power is supplied and commercial power is supplied to the lamp load 13, the specific power load 14, and the power load 15. In addition, it is also possible to supply the electric power stored in the storage battery 11 while generating power, and supply the electric power stored in the storage battery 11 at night to reduce the amount of received power.

  Starting from step 600, in step 605, the demand controller 19 monitors the amount of received power measured by the measuring device and determines whether or not there is a power failure according to the amount of received power. Whether or not there is a power failure can be determined based on whether or not the amount of received power is less than the second threshold. If it is determined that there is a power outage, the process proceeds to step 620. If it is determined that there is no power outage, the process proceeds to step 610.

  In step 610, the demand controller 19 determines whether or not the received power amount is equal to or greater than the first threshold value. If it is equal to or greater than the first threshold value, the process proceeds to step 620, and if it is less than the first threshold value, the process proceeds to step 615.

  In step 615, the demand controller 19 determines whether the set condition is met. When a period is set as a condition by season, day of the week, and time, it is determined whether the current season, day of the week, and time are within the set period. If the condition is met, the process proceeds to step 620; otherwise, the process returns to step 605. In addition, the process of step 605-step 615 is not restricted to this order, Any order may be sufficient, and at least 2 of these 3 processes may be implemented in parallel.

  In step 620, the demand controller 19 outputs a start command to the cogeneration 12. In step 625, the cogeneration 12 is activated in response to the activation command, and starts power generation. In step 630, the cogeneration 12 supplies the switching power source to the load power source switching board 26. In step 635, the load power supply switching board 26 switches the commercial power to the generated power generated by the cogeneration 12 and supplies the generated power to the specific power load 14. The specific power load 14 also includes a blower 23, a circulation pump 24, and a hot water supply pump 25.

  In step 640, the blower 23 and the circulation pump 24 are activated, water is circulated, exhaust heat is recovered from the exhaust gas discharged from the cogeneration 12, and hot water having a predetermined temperature is created in the hot water storage tank 22. In step 645, the hot water supply pump 25 is activated and hot water supply to the hot water supply load 20 is started.

  In step 650, the demand controller 19 determines whether a stop command has been output. If no stop command is output, the determination in step 650 is repeated. When the stop command is output, the process proceeds to step 655, where the cogeneration 12 receives the stop command, supplies the switching power source to the load power source switching panel 26, and switches from the generated power of the cogeneration 12 to the commercial power.

  In step 660, the operation of the cogeneration 12 is stopped, and the process returns to step 605. The blower 23, the circulation pump 24, and the hot water supply pump 25 may stop the supply of electric power in accordance with the switching to the commercial power, stop the operation thereof, or temporarily switch to the commercial power and continue the power supply. As the operation of the cogeneration 12 is stopped, these operations may be stopped. Moreover, about hot water supply pump 25, even after the operation stop of cogeneration 12, commercial power may be used and hot water supply may be continued.

  As described above, since power is generated by the cogeneration 12 and exhaust heat is recovered, the amount of received power can be reduced and energy efficiency can be improved. In the present system and method, even when the received power amount is less than the first threshold set as the management target value, the cogeneration 12 can be activated, the received power amount can be reduced, and the energy efficiency can be improved.

  Further, even when a power failure occurs, power can be supplied to the specific power load 14 without interrupting energization. For this reason, if the air conditioner is set as the specific power load 14, the air conditioner can be continuously used even during a power failure, and heat stroke and the like can be prevented.

  Furthermore, by setting conditions and starting and stopping the cogeneration 12, it is possible to suppress a power peak of the entire building to be controlled by the power control system, and to construct a system that does not rely only on power energy.

  The power control system and method of the present invention have been described in detail so far. However, the present invention is not limited to the above-described embodiments, and other embodiments, additions, modifications, deletions, and the like can be performed by those skilled in the art. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 10 ... Solar power generation panel 11 ... Storage battery 12 ... Cogeneration 13 ... Electric load 14 ... Specific electric power load 15 ... Power load 16 ... Power conditioner 17 ... Power-receiving / transforming cubicle 18 ... Specific load electric power light board 19 ... Demand controller 20 ... Hot water supply load 21 ... heat exchanger 22 ... hot water storage tank 23 ... blower 24 ... circulation pump 25 ... hot water supply pump 26 ... load power source switching board 27 ... specific load power board 28 ... power board 29 ... switch 30 ... CPU
31 ... ROM
32 ... RAM
33 ... Connection I / F
34 ... Storage medium 35 ... Storage control I / F
36 ... Display unit 37 ... Operation unit 40 ... Engine 41 ... Generator 42 ... Switch 43 ... Breaker 44 ... Power load

Claims (10)

A power control system for controlling power,
A measuring means for measuring the amount of received power;
Control means for outputting a start command according to the amount of received power measured by the measuring means and the set condition;
Power generation means that is activated in response to the activation command from the control means;
Switching means for receiving power supplied from the power generation means and switching the power supplied to the specific power load from the received power to the power generated by the power generation means;
A power control system comprising: a hot water supply means that operates by the generated power switched by the switching means, heats water with exhaust gas discharged from the power generation means, and supplies hot water to a hot water supply load.   When the switching means switches from the received power to the generated power, while maintaining the supply of the received power to the specific power load and enabling the supply of the generated power by connecting to the power generating means The power control system according to claim 1, wherein supply of the received power to the specific power load is stopped. The amount of received power is an average value of received power over a certain period of time,
The control unit is configured to receive the received power measured by the measuring unit when the received power amount measured by the measuring unit is equal to or greater than a first threshold, or at the start of a period set as the condition. The power control system according to claim 1 or 2, wherein the start command is output when the power is less than a second threshold value. The control means, after outputting the start command, outputs a stop command to stop the power generation means according to the received power amount measured by the measurement means and the set condition,
The electric power according to any one of claims 1 to 3, wherein the switching means switches the electric power supplied to the specific electric power load from the generated electric power to the received electric power in response to the stop of the electric power generating means. Control system. The amount of received power is an average value of received power over a certain period of time,
The control unit is configured to measure the power received by the measuring unit when the received power amount is less than a first threshold, or after the period set as the condition ends, or by the measuring unit. The power control system according to claim 4, wherein the stop command is output when the amount of received power is equal to or greater than the second threshold. A power control method executed by a power control system for controlling power, wherein the power control system includes a measurement unit, a control unit, a power generation unit, a switching unit, and a hot water supply unit,
The measuring means measures the amount of received power;
The control means outputting a start command in accordance with the measured amount of received power and a set condition;
Receiving the start command from the control means and starting the power generation means;
The switching means receives power supply from the power generation means and switches the power supplied to a specific power load from the received power to the power generation power of the power generation means; and the hot water supply means is switched by the switching means. And a step of heating water by the exhaust gas discharged from the power generation means and supplying hot water to a hot water supply load.   In the switching step, after switching from the received power to the generated power, while maintaining the supply of the received power to the specific power load, enabling the supply of the generated power by connecting to the power generation means The power control method according to claim 6, wherein supply of the received power to the specific power load is stopped. The amount of received power is an average value of received power over a certain period of time,
The step of outputting the start command is measured when the received power amount measured by the measuring unit is equal to or greater than a first threshold, or at the start of a period set as the condition, or by the measuring unit. The power control method according to claim 6 or 7, wherein the start command is output when the received power amount is less than a second threshold value. A step of outputting a stop command to stop the power generation unit according to the received power amount measured by the measurement unit and the set condition after the control unit outputs the start command;
9. The method according to claim 6, further comprising: switching the power supplied to the specific power load from the generated power to the received power when the switching unit is stopped. The power control method described in 1. The amount of received power is an average value of received power over a certain period of time,
The step of outputting the stop command is performed when the amount of received power measured by the measuring unit becomes less than a first threshold, after the period set as the condition ends, or by the measuring unit. The power control method according to claim 9, wherein the stop command is output when the measured amount of received power is equal to or greater than a second threshold.