JP2012100504A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system that can reliably implement stable power supply and long term power supply to a power load apparatus.SOLUTION: A power supply system S includes a power generation apparatus 5, a solar cell apparatus 6, a power storage apparatus 7, an inverter 14, a switch 15, power load apparatuses 3, 4, power converters 12A, 12B, 12C, and a control section 11 for controlling the operation of the power generation apparatus 5, inverter 14 and switch 15. During normal power supply from a commercial power supply 1, the control section 11 controls the operation of the power generation apparatus 5 and first power converter 12A to bring a received power from the commercial power supply 1 to a target received power, controls the operation of the second power converter 12B to maximize an output power from the solar cell apparatus 6 to a DC line 17, and controls the operation of the inverter 14 to bring a voltage of the DC line 17 to a normal setting DC voltage.

Description

  The present invention relates to a power supply system including a plurality of types of power supply devices.

  Conventionally, a power supply system including a plurality of types of power supply devices has been proposed. For example, Patent Document 1 describes a power supply system including a wind power generator, a solar power generator, a prime mover power generator, and a secondary battery as a power supply device. In this way, by providing a plurality of types of power supply devices, when the balance between power supply and demand is lost, the secondary battery first discharges or charges from the commercial system to suppress frequency fluctuations. Since the prime mover power generator adjusts the load so as to reduce the discharge amount of the secondary battery, the effect that the frequency fluctuation of the commercial system can be suppressed to an allowable value or less can be obtained.

  However, in the power supply system described in Patent Document 1, the power supply devices are connected to each other through an AC line. Therefore, a plurality of inverters are required to connect a plurality of power supply devices to the AC line separately. As a result, energy loss occurs during power conversion in the inverter. Therefore, when the number of inverters increases, there is a problem that the total energy loss increases when viewed in the entire power supply system.

  Patent Document 2 describes a power supply system including a solar battery and a storage battery as a power supply device. In the power supply system of Patent Document 2, the solar battery and the storage battery are first connected to each other via a DC line. And one inverter which connects a DC track and an AC track is provided. Therefore, there is an advantage that it is possible to reduce the occurrence of energy loss in the inverter that is problematic in Patent Document 1.

JP 11-69893 A JP-A-6-178461

  In paragraph 0006 of Patent Document 2, there is a description that power can be continuously supplied from the storage battery and the solar battery to the uninterruptible load by opening the switch at high speed during a power failure. However, the capacity of the storage battery is limited, and the power generation amount of the solar battery is limited according to the amount of solar radiation. For this reason, in the power supply system described in Patent Document 2, it is difficult to say that stable power supply to the uninterruptible load and power supply over a long period of time can be reliably performed at the time of a power failure of the commercial power supply.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a power supply system that can stably supply power to a power load device and supply power over a long period of time.

The characteristic configuration of the power supply system according to the present invention for achieving the above object is as follows:
A power generator connected to the DC line via the first power converter and generating power using fuel;
A solar cell device connected to the DC line via a second power converter;
A power storage device connected to the DC line via a third power converter;
An inverter that converts the DC power supplied from the DC line into AC power and outputs the AC power;
A switch capable of breaking the connection between the commercial power source and the AC side of the inverter;
A power load device connected to an AC line between the inverter and the switch, and capable of receiving AC power output from the inverter and AC power received from the commercial power source;
A controller that controls operations of the first power converter, the second power converter, the third power converter, the power generation device, the inverter, and the switch;
The control unit, when power supply from the commercial power supply is normally performed,
Controlling the operation of the power generator and the first power converter so that the received power from the commercial power source becomes the target received power; and
Controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized; and
The operation of the inverter is controlled so that the voltage of the DC line becomes a normal setting DC voltage.

According to the above characteristic configuration, since the power supply device, the solar cell device, and the power storage device are provided, a plurality of types of power supply devices are provided. Can supply. For example, even if power cannot be supplied from the solar cell device at night, power can be supplied from the power generation device and the power storage device, or even if fuel supply stops and power supply cannot be supplied from the power generation device, Can supply power. Moreover, if it is daytime, it can supply electric power from a solar cell apparatus over a long period of time, and if fuel supply is continued, it can supply electric power from a power generator over a long period of time.
In addition, the control unit controls the operations of the power generation device and the first power converter so that the received power from the commercial power supply becomes the target received power, whereby the received power from the commercial power supply can be stabilized.
Therefore, it is possible to provide a power supply system capable of reliably supplying stable power to the power load device and supplying power over a long period of time.

Another characteristic configuration of the power supply system according to the present invention is that, when the control unit is normally performing power supply from the commercial power supply,
Controls the operation of the third power converter so as to cause discharge from the power storage device to the DC line when the received power from the commercial power source rises to become a discharge start power that is greater than the target received power. To implement the received power suppression control,
In a state where the received power suppression control is being performed, the received power suppression control is stopped when the received power from the commercial power source decreases and becomes equal to or lower than the discharge stop power which is less than the discharge start power.

  According to the above characteristic configuration, after the received power from the commercial power source rises and becomes equal to or higher than the discharge start power greater than the target received power, the control unit becomes equal to or lower than the discharge stop power that is less than the discharge start power. Until then, the operation of the third power converter is controlled so as to discharge the power storage device to the DC line. As a result, it is possible to suppress the received power from the commercial power source from being equal to or higher than the discharge start power. Therefore, even if the maximum received power determined by the contract with the power company is kept low, if the discharge start power is set to a value smaller than the maximum received power, the actual received power The power can be prevented from exceeding the maximum received power.

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit is normally supplying power from the commercial power supply,
When the decrease rate of the output power from the solar cell device to the DC line becomes larger than the set decrease rate, the decrease rate of the AC output power of the inverter is set to the set inverter output decrease rate from the power storage device. Implementing output reduction suppression control for controlling the operation of the third power converter so as to cause discharge to the DC line,
In a state where the output decrease suppression control is being performed, when the decrease rate of the output power from the solar cell device to the DC line becomes small and less than the set decrease rate, the output decrease suppression control is stopped. is there.

When the generated power of the solar cell device is drastically reduced, the output power from the solar cell device to the DC line is also drastically reduced. As a result, the AC output power of the inverter is also drastically reduced. As a result, the power received from the commercial power supply increases rapidly. Such a rapid increase in received power leads to disturbing the stability of the commercial system.
However, according to this feature configuration, when the decrease rate of the output power from the solar cell device to the DC line becomes larger than the set decrease rate, the control unit reduces the decrease rate of the AC output power of the inverter to the set inverter output decrease rate. The output reduction suppression control for controlling the operation of the third power converter is performed so that the discharge from the power storage device to the DC line is performed. That is, even if the output power from the solar cell device to the DC line rapidly decreases, the reduction rate of the AC output power of the inverter is moderated to some extent by the output reduction suppression control. As a result, the power received from the commercial power supply does not increase rapidly, which can contribute to the stabilization of the commercial system. Further, for example, even in a power generation device that cannot increase the output suddenly, if the rate of decrease in the AC output power of the inverter is moderate to some extent, the output increase of the power generation device following the rate of decrease (that is, It is also possible to offset the decrease in output of the solar cell device to some extent by the increase in output of the power generation device).

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit is normally supplying power from the commercial power supply,
When the increase rate of the output power from the solar cell device to the DC line becomes larger than the set increase rate, the increase rate of the AC output power of the inverter becomes the set inverter output increase rate from the DC line. Implement output increase suppression control to control the operation of the third power converter so as to charge the power storage device,
In a state where the output increase suppression control is being performed, the output increase suppression control is stopped when the increase rate of the output power from the solar cell device to the DC line becomes smaller than the set increase rate. is there.

When the generated power of the solar cell device increases rapidly, the output power from the solar cell device to the DC line also increases abruptly. As a result, the AC output power of the inverter also increases abruptly. As a result, the power received from the commercial power supply decreases rapidly. Such a rapid decrease in received power leads to disturbing the stability of the commercial system.
However, according to this characteristic configuration, when the increase rate of the output power from the solar cell device to the DC line increases and exceeds the set increase rate, the control unit increases the increase rate of the AC output power of the inverter to the set inverter output increase rate. The output increase suppression control for controlling the operation of the third power converter is performed so that the power storage device is charged from the DC line. That is, even if the output power from the solar cell device to the DC line suddenly increases, the increase rate of the AC output power of the inverter is moderated to some extent by the output increase suppression control. As a result, the power received from the commercial power supply does not decrease rapidly, which can contribute to the stabilization of the commercial system. Further, for example, even in a power generation device that cannot reduce the output rapidly, if the increase rate of the AC output power of the inverter is moderate to some extent, the output decrease following the increase rate (ie, solar cell) It is also possible to offset the increase in the output of the device to some extent by the decrease in the output of the power generator.

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit is normally supplying power from the commercial power supply,
The third power converter is configured to charge the power storage device when the power storage device is not charged / discharged and the power storage amount of the power storage device is less than a maximum value and the power generation device has an output margin. The point is to control the operation.

  According to the above characteristic configuration, the control unit can increase the amount of electricity stored by charging the electricity storage device at an appropriate timing. In other words, it is possible to prepare a system for performing long-term discharge from the power storage device.

Still another characteristic configuration of the power supply system according to the present invention is that the switch is configured by a semiconductor switch circuit,
When it is determined that a power failure has occurred in the commercial power source, the control unit operates the switch to cut off the connection between the commercial power source and the AC side of the inverter.

  According to the above characteristic configuration, since the switch is composed of a semiconductor switch circuit, the switching operation can be performed in a very short time. As a result, if the control unit immediately cuts off the connection between the commercial power source and the AC side of the inverter at the timing when it is determined that a power failure has occurred in the commercial power source, the power load device (i.e., the inverter and Power load device connected to AC line between switch and AC power output from inverter and AC power received from commercial power supply) The AC power output from the inverter can be continuously supplied.

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit has a power failure in the commercial power supply,
Controlling the operation of the power generator and the first power converter so that the voltage of the DC line becomes a set DC voltage at the time of a power failure, and
Controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized; and
The operation of the inverter is controlled so that the voltage of the AC line becomes the set AC voltage during a power failure.

  According to the above characteristic configuration, when a power failure occurs at the commercial power source, the control unit supplies the maximum power from the solar cell device to the DC line, and then the DC power is generated by the power generation device and the first power converter. Maintain the line voltage at the set DC voltage during a power failure. That is, the control unit can balance the supply and demand of power by maintaining the voltage of the DC line at the set DC voltage during a power failure.

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit has a power failure in the commercial power supply,
Performing voltage maintenance control for controlling the operation of the third power converter so that the voltage of the DC line becomes the DC voltage set at the time of power failure,
The power storage device is charged when the voltage maintenance control is not performed and the power storage amount of the power storage device is less than a maximum value and the power generation device and / or the solar cell device has an output margin. The point is to control the operation of the third power converter.

According to the above characteristic configuration, when a power failure occurs in the commercial power supply, the control unit causes the power storage device to discharge from the DC line in order to maintain the DC line voltage at the set DC voltage during the power failure. Can do. As a result, the control unit can balance the power supply and demand by maintaining the voltage of the DC line at the set DC voltage during a power failure.
In addition, the control unit charges the power storage device at a timing when the voltage maintenance control is not performed and the power storage amount of the power storage device is less than the maximum value and the power generation device and / or the solar cell device has an output margin. Thus, the amount of stored electricity can be increased. In other words, it is possible to prepare a system for performing long-term discharge from the power storage device. Here, as an example that can be considered that the power generator has an output margin, a state where the power generator is not operated at the rated output can be cited. Moreover, as an example that can be considered that the solar cell device has an output margin, a state in which the second power converter supplies power equal to or lower than the maximum power point to the DC line can be cited.

Still another characteristic configuration of the power supply system according to the present invention is that, when the control unit has a power failure in the commercial power supply,
When operating the power generator, controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized, and
When the power generation device is not operated, the operation of the second power converter is controlled so that the voltage of the DC line becomes the set DC voltage at the time of power failure.

  According to the above characteristic configuration, when the control unit is operating the power generation device, the control unit controls the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized. Large power can be supplied to the power load device. In addition, when the power generation device is not operated, the control unit controls the operation of the second power converter so that the voltage of the DC line becomes the set DC voltage at the time of power failure, thereby balancing the power supply and demand. Can do.

It is a figure which shows the structure of an electric power supply system. It is a flowchart explaining charging / discharging control according to received electric power. It is a figure explaining the magnitude | size of discharge start electric power and discharge stop electric power compared with target received electric power and maximum received electric power. It is a flowchart explaining charging / discharging control according to the reduction | decrease in the output electric power of a solar cell apparatus (2nd power converter). It is a flowchart explaining charging / discharging control according to the increase in the output electric power of a solar cell apparatus (2nd power converter). It is a flowchart explaining the operation control of the 2nd power converter to which a solar cell apparatus is connected. It is a flowchart explaining operation control of a power generator and a 1st power converter.

A power supply system according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of the power supply system S. As illustrated, the power supply system S includes a power generation device 5 that generates power using fuel, a solar cell device 6, and a power storage device 7 as a plurality of types of power supply devices. In the power supply system S, the power generation device 5 is connected to the DC line 17 via the first power converter 12A, and the solar cell device 6 is connected to the DC line 17 via the second power converter 12B. Is connected to the DC line 17 via the third power converter 12C. In addition, the power supply system S cuts off the connection between the inverter 14 that converts the DC power supplied from the DC line 17 into AC power and outputs it to the AC side, and the commercial power supply 1 and the AC side of the inverter 14. Important power that is connected to the AC switch 18 between the possible switch 15 and the inverter 14 and the switch 15 and can receive AC power output from the inverter 14 and AC power received from the commercial power source 1. And a power load device 4 as a load device (for example, a server device). Furthermore, the power supply system S includes a control unit 11 that controls operations of the first power converter 12A, the second power converter 12B, the third power converter 12C, the power generation device 5, the inverter 14, and the switch 15. A power system 3 that connects the commercial power source 1 and the switch 15 is connected to a power load device 3 as a general power load device (for example, an air conditioner).

In the present embodiment, the first power converter 12 </ b> A, the second power converter 12 </ b> B, the third power converter 12 </ b> C, the inverter 14, the switch 15, and the control unit 11 are integrally configured as the multi-source power converter 10. Yes. The multi-source power conversion device 10 includes a plurality of power supply side connection terminals 13A, 13B, 13C, a system side connection terminal 16, and a load side connection terminal 22. The power generator 5 is electrically connected to the first power supply side connection terminal 13A connected to the first power converter 12A. The solar cell device 6 is electrically connected to the second power supply side connection terminal 13B connected to the second power converter 12B. The power storage device 7 is electrically connected to the third power supply side connection terminal 13C connected to the third power converter 12C. The commercial system 2 is electrically connected to the system side connection terminal 16 connected to the switch 15. A power load device 4 as an important power load device is electrically connected to the load side connection terminal 22.
If the control of the first power converter 12A, the second power converter 12B, and the third power converter 12C connected to the power supply side connection terminals 13A, 13B, and 13C is appropriately changed, the power supply side connection terminals 13A. , 13B, 13C can be connected to various types of power supply devices.

The power generation device 5 is a device that generates power using fuel. For example, a power generation device including an engine that operates by consuming fuel and a generator that generates power using the driving force of the engine, or a power generation device such as a fuel cell can be used. Therefore, if the fuel is not exhausted, power generation can be reliably continued for a long time.
The solar cell device 6 is a power generation device that absorbs sunlight and performs photoelectric conversion. The output power of the solar cell device 6 changes according to the intensity of sunlight, and the desired output power cannot always be obtained.
The power storage device 7 is a device having a power storage function, such as a storage battery, an electric double layer capacitor, or a flywheel.

The first power converter 12 </ b> A converts the power supplied from the power generation device 5 into predetermined DC power and supplies it to the DC line 17. The second power converter 12 </ b> B converts the power supplied from the solar cell device 6 into predetermined DC power and supplies it to the DC line 17. The third power converter 12 </ b> C can control charging from the DC line 17 to the power storage device 7 and discharging from the power storage device 7 to the DC line 17.
The inverter 14 is a power converter that converts DC power supplied from the DC line 17 into predetermined AC power and outputs the AC power to the AC side.
The switch 15 is composed of a semiconductor switch circuit. In the present embodiment, the switch 15 has a circuit configuration configured by connecting two thyristors in reverse parallel, but may have another circuit configuration.

  The received power of the power supply system S is measured by the wattmeter 21 and input to the control unit 11. The storage amount (voltage) of the power storage device 7 is measured by the voltmeter 19 and input to the control unit 11. The voltage of the AC line 18 is measured by the voltmeter 20 and input to the control unit 11. The voltage of the DC line 17 is measured by the voltmeter 23 and input to the control unit 11.

  Next, the operation of the control unit 11 will be described separately for cases where power supply from the commercial power source 1 is normally performed and when a power failure occurs in the commercial power source 1.

<When commercial power is normal>
The control unit 11 controls the operations of the power generation device 5 and the first power converter 12A so that the received power from the commercial power source 1 becomes the target received power when the power supply from the commercial power source 1 is normally performed. And the operation of the second power converter 12B is controlled so that the output power from the solar cell device 6 to the DC line 17 is maximized (that is, the maximum power point tracking (MPPT) control is performed), In addition, the operation of the inverter 14 is controlled so that the voltage of the DC line 17 becomes a normal setting DC voltage.

  Specifically, even if the power supplied from the power generator 5 to the DC line 17 via the first power converter 12A is constant, the wattmeter 21 is changed if the output of the solar cell device 6 changes every moment. The received power that is measured at the time also changes every moment. Therefore, the control unit 11 refers to the measurement result of the wattmeter 21 so that the received power is constant at the target received power even if there is a change in the output of the solar cell device 6, and the power generator 5 and the first power. The operation of the converter 12A is controlled.

  Furthermore, when the power supply from the commercial power source 1 is normally performed, the control unit 11 controls the charge / discharge control according to the received power and the output power of the solar cell device 6 for the third power converter 12C. The three charge / discharge controls, namely, the corresponding charge / discharge control and the charge / discharge control according to the amount of power stored in the power storage device 7 are performed in parallel. The charge / discharge control will be described below.

[Charge / discharge control according to received power]
FIG. 2 is a flowchart for explaining charge / discharge control in accordance with received power. FIG. 3 is a diagram illustrating the magnitudes of the discharge start power and the discharge stop power described in the flowchart of FIG. 2 in comparison with the target received power and the maximum received power. As shown in FIG. 3, in the present embodiment, the maximum received power> the discharge start power> the discharge stop power> the target received power.

  The charge / discharge control shown in FIG. 2 is performed for the purpose of reducing the received power by discharging from the power storage device 7 when the received power in the power supply system S approaches the maximum received power. Therefore, when the power supply from the commercial power source 1 is normally performed and the received power from the commercial power source 1 increases and becomes equal to or higher than the discharge start power, the control unit 11 supplies power from the power storage device 7 to the DC line 17. In a state where the received power suppression control for controlling the operation of the third power converter 12C to perform discharge is performed and the received power suppression control is being performed, the received power from the commercial power source 1 decreases and discharge starts. When the discharge stop power is less than or equal to the power, the received power suppression control is stopped.

Specifically, in step 100, the control unit 11 determines whether the received power measured by the wattmeter 21 is equal to or higher than the discharge start power. As described above, the control unit 11 operates the power generator 5 and the first power converter 12A so that the received power from the commercial power source 1 becomes the target received power (that is, the output from the power generator 5 to the DC line 17). Power). However, when the power load of the power load devices 3 and 4 is increased, when the output power from the solar cell device 6 to the DC line 17 is decreased, or when the power generator 5 has no output margin (for example, For example, when the power generation device 5 is operated at the rated output), the received power measured by the wattmeter 21 may exceed the target received power. In the present embodiment, the received power simply allows the received power to exceed the target received power, but does not allow the received power to exceed the maximum received power illustrated in FIG. Therefore, when the control unit 11 determines in step 100 that the received power approaches the maximum received power and becomes equal to or greater than the discharge start power, the control unit 11 proceeds to step 102 and causes the power storage device 7 to discharge from the DC line 17. Attempt to reduce received power.
If the control unit 11 determines in step 100 that the received power is less than the discharge start power, the control unit 11 returns to the beginning of this flowchart.

When control unit 11 causes discharge from power storage device 7 to DC line 17 in step 102, the received power measured by wattmeter 21 decreases. Further, when the power load of the power load devices 3 and 4 decreases with time, or when the output power from the solar cell device 6 to the DC line 17 starts to increase, the received power also decreases due to these factors. .
Therefore, in step 104, the control unit 11 determines whether or not the received power measured by the wattmeter 21 has decreased below the discharge stop power illustrated in FIG. This is because if the received power is reduced below the discharge stop power, it is no longer necessary to discharge the power storage device 7.

When the control unit 11 determines in step 104 that the received power has decreased below the discharge stop power, the control unit 11 proceeds to step 106 and stops the discharge from the power storage device 7 to the DC line 17.
On the other hand, when the control unit 11 determines in step 104 that the received power has not decreased below the discharge stop power, the control unit 11 performs the determination process in step 104 again after a predetermined time, for example.

  As described above, by performing the charge / discharge control shown in FIG. 2, even if the received power in the power supply system S approaches the maximum received power, the received power can be prevented from exceeding the maximum received power.

[Charge / discharge control according to the output power of the solar cell device]
FIG. 4 is a flowchart for explaining the charge / discharge control according to the decrease in the output power from the solar cell device 6 to the DC line 17. For example, when the responsiveness of the power generator 5 is poor (that is, when the maximum increase rate of the power supplied from the power generator 5 and the first power converter 12A to the DC line 17 is small), the power generator 5 is controlled by the maximum power point tracking control. When the output power from the solar cell device 6 and the second power converter 12B to the DC line 17 rapidly decreases, the sudden decrease in output power is the increase in output power from the power generator 5 to the DC line 17 There is a possibility that a situation may occur in which the amount of received power cannot be offset and the received power rapidly increases. The charge / discharge control according to the decrease in output power shown in FIG. 4 is performed for the purpose of avoiding such a situation where the received power is rapidly increased.

  That is, the control unit 11 reduces the output power of the solar cell device 6 (that is, the output power from the second power converter 12B to the DC line 17) when the power supply from the commercial power source 1 is normally performed. When the speed increases and becomes equal to or higher than the set reduction speed, the third power conversion is performed such that the discharge from the power storage device 7 to the DC line 17 is performed so that the reduction speed of the AC output power of the inverter 14 becomes the set inverter output reduction speed. In the state where the output reduction suppression control for controlling the operation of the device 12C is performed and the output reduction suppression control is being executed, when the decrease rate of the output power of the solar cell device 6 becomes smaller than the set decrease rate, the output Stop reduction suppression control.

Specifically, in step 200, the control unit 11 determines whether or not the decrease rate of the output power from the solar cell device 6 to the DC line 17 measured by the wattmeter 24 is equal to or higher than the set decrease rate. When the decrease rate of the output power from the solar cell device 6 to the DC line 17 becomes equal to or higher than the set decrease rate, the AC output power of the inverter 14 measured by the wattmeter 20 also rapidly decreases and is measured by the wattmeter 21. The received power increases rapidly. Such a rapid fluctuation of the received power that would greatly disturb the stability of the commercial system 2 is not preferable. Therefore, if the control part 11 determines with the reduction | decrease rate of the output electric power from the solar cell apparatus 6 to the DC line 17 being more than a setting reduction | decrease speed in the process 200, it will transfer to the process 202 and AC of the inverter 14 as an index The power storage device 7 is discharged so that the decrease rate of the output power becomes the set inverter output decrease rate.
If the control unit 11 determines in step 200 that the reduction rate of the output power from the solar cell device 6 to the DC line 17 is less than the set reduction rate, the control unit 11 returns to the beginning of this flowchart.

  When the control unit 11 causes the power storage device 7 to discharge from the power line 7 to the DC line 17 in Step 202, the AC output power decrease rate of the inverter 14 decreases and approaches the set inverter output decrease rate. It is possible to avoid a sudden increase in received power. However, it is necessary to continue discharging from the power storage device 7 until the decrease rate of the output power from the solar cell device 6 to the DC line 17 becomes less than the set decrease rate. Therefore, in step 204, the control unit 11 determines whether or not the decrease rate of the output power from the solar cell device 6 to the DC line 17 is less than the set decrease rate. When the control unit 11 determines in step 204 that the reduction rate of the output power from the solar cell device 6 to the DC line 17 is less than the set reduction rate, the control unit 11 proceeds to step 206 and stops discharging from the power storage device 7. To do. On the other hand, when the control unit 11 determines in step 204 that the reduction rate of the output power from the solar cell device 6 to the DC line 17 is equal to or higher than the set reduction rate, the process returns to the beginning of this flowchart.

  As described above, even if the output power from the solar cell device 6 to the DC line 17 is sharply reduced by performing the charge / discharge control according to the decrease in the output power of the solar cell device 6 shown in FIG. The rate of decrease in AC output power is moderated to some extent. As a result, the power received from the commercial power supply 1 does not increase rapidly. For example, even in the power generation device 5 that cannot increase the output rapidly, if the rate of decrease in the AC output power of the inverter 14 is moderate to some extent, the output can be increased following the rate of decrease. Become. As a result, it is possible to avoid a sudden increase in the received power measured by the wattmeter 21.

  FIG. 5 is a flowchart for explaining charge / discharge control according to an increase in output power from the solar cell device 6 to the DC line 17. For example, when the responsiveness of the power generator 5 is poor (that is, when the maximum reduction rate of the power supplied from the power generator 5 and the first power converter 12A to the DC line 17 is small), the power generator 5 is controlled by the maximum power point tracking control. When the output power from the solar cell device 6 and the second power converter 12B to the DC line 17 suddenly increases, the sudden increase in output power is reduced by the decrease in output power from the power generator 5 to the DC line 17. There is a possibility that a situation may occur in which the received power cannot be offset and the received power rapidly decreases. The charge / discharge control according to the increase in output power shown in FIG. 5 is performed for the purpose of avoiding such a situation where the received power is rapidly reduced.

  That is, the control unit 11 increases the output power of the solar cell device 6 (that is, the output power from the second power converter 12B to the DC line 17) when the power supply from the commercial power source 1 is normally performed. When the speed increases and exceeds the set increase speed, the third power conversion is performed so that charging from the DC line 17 to the power storage device 7 is performed so that the increase speed of the AC output power of the inverter 14 becomes the set inverter output increase speed. In the state where the output increase suppression control for controlling the operation of the battery 12C is performed and the output increase suppression control is being performed, when the increase rate of the output power of the solar cell device 6 becomes smaller than the set increase rate, the output Stop increase suppression control.

  Specifically, in step 500, the control unit 11 determines whether or not the increase rate of the output power from the solar cell device 6 to the DC line 17 measured by the wattmeter 24 is equal to or higher than the set increase rate. When the increase speed of the output power from the solar cell device 6 to the DC line 17 becomes equal to or higher than the set increase speed, the AC output power of the inverter 14 measured by the wattmeter 20 also rapidly increases and is measured by the wattmeter 21. The received power will decrease rapidly. Such a rapid fluctuation of the received power that would greatly disturb the stability of the commercial system 2 is not preferable. Therefore, if the control part 11 determines in step 500 that the increase rate of the output power from the solar cell device 6 to the DC line 17 is equal to or higher than the set increase rate, the control unit 11 proceeds to step 502 and, on the other hand, from the solar cell device 6 to the DC line. If it is determined that the increase rate of the output power to 17 is less than the set increase rate, the process returns to the beginning of this flowchart.

In step 502, the control unit 11 determines whether or not the system is capable of suppressing a rapid decrease in received power by charging the power storage device 7 from the DC line 17. Specifically, in step 502, control unit 11 determines whether or not the amount of power stored in power storage device 7 is the maximum value. Then, when the amount of electricity stored in the power storage device 7 is not the maximum value (that is, when there is remaining charge capacity), the control unit 11 proceeds to step 504 and sets the rate of increase in the AC output power of the inverter 14 as an index. Charging from the DC line 17 to the power storage device 7 is performed so that the inverter output increases.
On the other hand, when the amount of power stored in the power storage device 7 is the maximum value (that is, when there is no remaining charge capacity), the control unit 11 proceeds to Step 510.

  When the control unit 11 causes the power storage device 7 to be charged from the DC line 17 in step 504, the increase rate of the AC output power of the inverter 14 decreases and approaches the set inverter output increase rate. It is possible to avoid a sudden decrease in the received power. However, it is necessary to continue charging by the power storage device 7 until the increase rate of the output power from the solar cell device 6 to the DC line 17 becomes less than the set increase rate. Therefore, in step 506, the control unit 11 determines whether or not the increase rate of the output power from the solar cell device 6 to the DC line 17 is less than the set increase rate. If the control unit 11 determines in step 506 that the increase rate of the output power from the solar cell device 6 to the DC line 17 is less than the set increase rate, the control unit 11 proceeds to step 508 and stops charging by the power storage device 7. To do. In contrast, if the control unit 11 determines in step 506 that the increase rate of the output power from the solar cell device 6 to the DC line 17 is equal to or higher than the set increase rate, the control unit 11 returns to the beginning of this flowchart.

When the control unit 11 determines in step 502 that the amount of power stored in the power storage device 7 is the maximum value (that is, there is no remaining charge), the control unit 11 suppresses the follow-up speed to the maximum power point more than usual in step 510. The operation of the second power converter 12B is controlled. For example, the control unit 11 performs control to reduce the output power from the power generation device 5 and the first power converter 12A to the DC line 17 so that the received power from the commercial power source 1 becomes the target received power. In step 510, the control unit 11 makes the output decrease rate from the first power converter 12A the same as the output increase rate from the second power converter 12B (that is, the output decrease from the first power converter 12A). And the increase in output from the second power converter 12B are offset), the operation of the second power converter 12B is controlled so as to adjust the follow-up speed to the maximum power point. And control part 11 will complete adjustment of the rate of increase in output from the 2nd power converter 12B, if it will be in the state where charge to power storage device 7 is attained.
As described above, control unit 11 causes power storage device 7 to be charged from DC line 17 in step 504 in a state where power storage device 7 can be charged, and to the maximum power point in step 510 in a state where power storage device 7 cannot be charged. The operation of the second power converter 12B is controlled so as to suppress the follow-up speed of.

  As described above, even if the output power from the solar cell device 6 to the DC line 17 is rapidly increased by performing charge / discharge control according to the increase in the output power of the solar cell device 6 shown in FIG. The rate of increase in AC output power is moderated to some extent. As a result, the power received from the commercial power source 1 is not suddenly reduced. Further, for example, even in the power generation device 5 in which the output cannot be decreased rapidly, if the increase rate of the AC output power of the inverter 14 is moderate to some extent, the output can be decreased following the increase rate. Become. As a result, it is possible to avoid a sudden decrease in the received power measured by the wattmeter 21.

[Charge / discharge control according to the amount of electricity stored in the electricity storage device]
In order to perform charge / discharge control as described above using the power storage device 7, it is necessary to maintain the power storage amount of the power storage device 7 within an appropriate range (preferably the maximum value). Therefore, when the power supply from the commercial power source 1 is normally performed, the control unit 11 does not charge / discharge the power storage device 7 as described above, and the power storage amount of the power storage device 7 is less than the maximum value. The operation of the third power converter 12C is controlled so that the power storage device 7 is charged when there is an output margin in the power generation device 5. As a result, the amount of power stored in the power storage device 7 can be increased at an appropriate timing.

<Commercial power failure>
When determining that a power failure has occurred in the commercial power source 1, the control unit 11 operates the switch 15 to disconnect the connection between the commercial power source 1 and the AC side of the inverter 14. Specifically, the control unit 11 can detect that a power failure has occurred in the commercial power source 1 from the change in voltage measured by the voltmeter 25. In the present embodiment, since the switch 15 is constituted by a semiconductor switch circuit (for example, a thyristor as shown in FIG. 1), the connection between the commercial power source 1 and the AC side of the inverter 14 is performed in a very short time. Can be blocked.

  Specifically, when the control unit 11 determines that a power failure has occurred in the commercial power source 1, the control unit 11 operates the switch 15 to immediately disconnect the connection between the commercial power source 1 and the AC side of the inverter 14, As will be described below, the operation control of the power generation device 5 and the first power converter 12A, the operation control of the second power converter 12B, and the operation control of the third power converter 12C are performed in parallel.

[Operation control of second power converter (solar cell device)]
FIG. 6 is a flowchart illustrating operation control of the second power converter 12B to which the solar cell device 6 is connected. As shown in the figure, in step 300, the control unit 11 determines whether or not the power generation device 5 is operating. As will be described later, the control unit 11 does not cause the power generation device 5 to operate when the power load of the power load device 4 as the important power load device is very small. And the control part 11 switches the operation control of the 2nd power converter 12B with the time of carrying out driving | operation implementation of the electric power generating apparatus 5, and the time of not carrying out driving | operation implementation. Specifically, when the power generation device 5 is operating, the control unit 11 proceeds to Step 302 so that the output power from the solar cell device 6 to the DC line 17 is maximized. 12B operation control (that is, maximum power point tracking control) is performed. On the other hand, when the power generation device 5 is not operating, the control unit 11 proceeds to step 304 and the solar cell device 6 changes the direct current line so that the voltage of the direct current line 17 becomes the set direct current voltage during a power failure. The output power to 17 is controlled by the operation of the second power converter 12B.

  As described above, when the power generation device 5 is not operating, the control unit 11 can make the solar cell device 6 work to maintain the voltage of the DC line 17 constant and balance the supply and demand of power. it can. In addition, when the power generation device 5 is operating, since the power generation device 5 plays a role of maintaining the voltage of the DC line 17 as will be described later, the control unit 11 allows the solar cell device 6 to supply the maximum power to the DC line. 17 can be used to feed.

[Operation control of third power converter (power storage device)]
The control unit 11 performs voltage maintenance control for controlling the operation of the third power converter 12 </ b> C so that the voltage of the DC line 17 becomes the set DC voltage at the time of power failure when a power failure occurs in the commercial power source 1. That is, the control unit 11 can balance the supply and demand of electric power by discharging from the power storage device 7 to the DC line 17 or charging from the DC line 17 to the power storage device 7. By performing this voltage maintenance control, even if the output of the solar cell device 6 varies greatly, the variation is compensated by charging / discharging of the power storage device 7.
In addition, when the power failure occurs in the commercial power source 1, the control unit 11 does not perform the voltage maintenance control, the power storage amount of the power storage device 7 is less than the maximum value, and the power generation device 5 or the solar cell device 6 or The operation of the third power converter 12C is controlled so that the power storage device 7 is charged when both have an output margin. That is, the control unit 11 can increase the amount of electricity stored by charging the electricity storage device 7 at an appropriate timing. In the present embodiment, “the power generating device 5 has an output margin” means that the power generating device 5 is not operating at the rated output and the output can be further increased. Further, “the solar cell device 6 has an output margin” means that the second power converter 12B supplies power below the maximum power point to the DC line 17, and the voltage of the DC line 17 is equal to the set DC voltage at the time of power failure. This means that the operation of the second power converter 12B is controlled.

[Operation control of power generator and first power converter]
FIG. 7 is a flowchart for explaining operation control of the power generation device 5 and the first power converter 12A.
As shown in the figure, in step 400, the control unit 11 determines whether or not the operation execution condition of the power generator 5 is satisfied. For example, when the capacity of the power load device 4 is sufficiently small with respect to the capacity of the solar cell device 6 and the solar cell device 6 is generating power, the control unit 11 does not satisfy the operation execution condition (that is, It is not necessary to operate the power generation device 5). If the control unit 11 determines that the operation execution condition is not satisfied, the control unit 11 proceeds to step 414 and does not perform the operation of the power generation device 5, and otherwise (step 402) otherwise (when the operation execution condition is determined to be satisfied). Then, the power generation device 5 is operated.

  In the case where the power generation device 5 is in operation, the control unit 11 performs the operations of the power generation device 5 and the first power converter 12A so that the voltage of the DC line 17 becomes the set DC voltage at the time of power failure in Steps 404 to 412. Control. Specifically, in step 404, the control unit 11 determines whether or not the voltage of the DC line 17 measured by the voltmeter 23 is higher than the set DC voltage during a power failure. In step 408, the control unit 11 It is determined whether the voltage of the DC line 17 measured at 23 is lower than the set DC voltage at the time of power failure. Then, when the voltage of the DC line 17 is higher than the set DC voltage during a power failure, the control unit 11 causes the power generator 5 and the first power conversion to decrease the output power from the power generator 5 to the DC line 17 in Step 406. The operation of the device 12A is controlled. Further, when the voltage of the DC line 17 is lower than the set DC voltage at the time of power failure, the control unit 11 increases the power generation apparatus 5 and the first power conversion in a direction to increase the output power from the power generation apparatus 5 to the DC line 17 in Step 410. The operation of the device 12A is controlled. Alternatively, when the voltage of the DC line 17 is the same as the set DC voltage during a power failure, the control unit 11 causes the power generator 5 and the power generator 5 to maintain the current output power from the power generator 5 to the DC line 17 in Step 412. The operation of the first power converter 12A is controlled.

  At this time, the control unit 11 controls the operation of the second power converter 12B so that the output power from the solar cell device 6 is maximized, as shown in Step 302 of FIG. Moreover, the control part 11 controls the operation | movement of the inverter 14 so that the voltage of the alternating current line 18 may turn into a setting alternating voltage at the time of a power failure.

  As described above, when the voltage of the DC line 17 measured by the voltmeter 23 deviates from the set DC voltage at the time of power failure, the control unit 11 performs charge / discharge control (the voltage maintenance control) of the power storage device 7 and the power generation device. 5 and the operation control (power generation control) of the first power converter 12A are performed in parallel. Further, the charge / discharge of the power storage device 7 is more responsive than the change in the output power from the power generation device 5 to the DC line 17. Therefore, the control unit 11 detects that the voltage of the DC line 17 has deviated from the set DC voltage during a power failure, and performs charge / discharge control of the power storage device 7 and operation control of the power generation device 5 and the first power converter 12A. Are simultaneously started, the voltage of the DC line 17 may be quickly adjusted to the set DC voltage at the time of a power failure by charging / discharging the power storage device 7 with good responsiveness. Thus, even if the voltage of the DC line 17 has already been adjusted to the set DC voltage during a power failure, the control unit 11 continues without stopping the operation control of the power generation device 5 and the first power converter 12A. To do. That is, the control unit 11 continues the control so that the sum of the output power from the power generation device 5 to the DC line 17 and the output power from the solar cell device 6 to the DC line 17 becomes the power required by the power load device 4. I can say that.

  As a result, the charge / discharge control of the power storage device 7 and the operation control of the power generation device 5 and the first power converter 12A are performed in an overlapping manner, so that the voltage of the DC line 17 changes more than necessary. However, the control unit 11 performs the charge / discharge control of the power storage device 7 again to adjust the voltage of the DC line 17 back to the set DC voltage at the time of a power failure (that is, the charge / discharge control of the power storage device 7 performed first). Control to cancel). As a result, the voltage of the DC line 17 is performed only by the operation control of the power generator 5 and the first power converter 12A. That is, the charge / discharge control of the power storage device 7 is performed to compensate for poor response of output fluctuations of the power generation device 5 and the first power converter 12A.

  As described above, since the power generation device 5, the solar cell device 6, and the power storage device 7 are provided with a plurality of types of power supply devices, even if power cannot be supplied from any of the power supply devices, the remaining power supply devices Can supply power. For example, even if it becomes impossible to supply power from the solar cell device 6 at night, it is possible to supply power from the power generation device 5 and the power storage device 7, or even if fuel supply stops and power supply cannot be supplied from the power generation device 5. 6 and the power storage device 7 can supply power. Moreover, if it is daytime, it can supply electric power from the solar cell apparatus 6 over a long period, and if fuel supply is continued, it can supply electric power from the electric power generating apparatus 5 over a long period of time. In addition, the control unit 11 stabilizes the received power from the commercial power source 1 by controlling the operations of the power generation device 5 and the first power converter 12A so that the received power from the commercial power source 1 becomes the target received power. Can be made. Therefore, it is possible to provide a power supply system S that can reliably supply a stable power supply to the power load device 4 that is an important power load device and a power supply over a long period of time.

<Another embodiment>
<1>
In the above-described embodiment, the example in which the power supply system S includes one power generation device 5, one solar cell device 6, and one power storage device 7 has been described. However, a plurality of these devices may be provided. In such a case, the power generation device 5, the solar cell device 6, or the power storage device 7 that is newly provided may be connected to the DC line 17 via the power converter. At this time, another type of device may be provided as the power generation device 5. For example, two power generation devices 5, which are a power generation device composed of an engine that consumes fuel and operates and a power generator that operates using the driving force of the engine, and a power generation device composed of a fuel cell are provided. It may be provided. Similarly, two different types of devices, that is, a storage battery and an electric double layer capacitor, may be provided as the power storage device 7.

  Thus, when another type of apparatus is provided, there is an advantage that the advantages of each apparatus can be utilized. For example, a storage battery is vulnerable to repeated charge and discharge (that is, deteriorates early), but can be discharged for a long time because the amount of electricity stored is large, and an electric double layer capacitor can only be discharged for a short time because the amount of electricity stored is small. Although it cannot be discharged, it is resistant to repeated charging and discharging and is maintenance-free.

<2>
In the above embodiment, the values used as indices when the control unit 11 performs various controls are exemplified, but these values can be appropriately set according to the apparatus configuration and the like. For example, the maximum received power related to the received power from the commercial power source 1 illustrated in FIG. 2, the discharge start power, the discharge stop power, the target received power, the set decrease speed and the set increase speed related to the output power of the solar cell device 6, an inverter The set inverter output decrease speed and the set inverter output increase speed related to the AC output power of 14 can be set as appropriate.

  INDUSTRIAL APPLICABILITY The present invention can be used in a power supply system that can reliably supply a stable power supply to a power load device and supply power over a long period of time.

1 Commercial power supply 4 Power load device (important power load device)
DESCRIPTION OF SYMBOLS 5 Electric power generating apparatus 6 Solar cell apparatus 7 Power storage apparatus 11 Control part 12A 1st power converter 12B 2nd power converter 12C 3rd power converter 14 Inverter 15 Switch 17 DC line 18 AC line S Power supply system

Claims (9)

A power generator connected to the DC line via the first power converter and generating power using fuel;
A solar cell device connected to the DC line via a second power converter;
A power storage device connected to the DC line via a third power converter;
An inverter that converts the DC power supplied from the DC line into AC power and outputs the AC power;
A switch capable of breaking the connection between the commercial power source and the AC side of the inverter;
A power load device connected to an AC line between the inverter and the switch, and capable of receiving AC power output from the inverter and AC power received from the commercial power source;
A controller that controls operations of the first power converter, the second power converter, the third power converter, the power generation device, the inverter, and the switch;
The control unit, when power supply from the commercial power supply is normally performed,
Controlling the operation of the power generator and the first power converter so that the received power from the commercial power source becomes the target received power; and
Controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized; and
The power supply system which controls operation | movement of the said inverter so that the voltage of the said DC line becomes a setting DC voltage at the time of normal. The control unit, when power supply from the commercial power supply is normally performed,
Controls the operation of the third power converter so as to cause discharge from the power storage device to the DC line when the received power from the commercial power source rises to become a discharge start power that is greater than the target received power. To implement the received power suppression control,
In the state which is performing the said received power suppression control, when the received power from the said commercial power supply falls and becomes below the discharge stop power which is less than the said discharge start power, the said received power suppression control is stopped. The power supply system described. The control unit, when power supply from the commercial power supply is normally performed,
When the decrease rate of the output power from the solar cell device to the DC line becomes larger than the set decrease rate, the decrease rate of the AC output power of the inverter is set to the set inverter output decrease rate from the power storage device. Implementing output reduction suppression control for controlling the operation of the third power converter so as to cause discharge to the DC line,
The output reduction suppression control is stopped when the reduction rate of the output power from the solar cell device to the DC line becomes smaller than the set reduction rate in the state where the output reduction suppression control is being performed. The power supply system according to 1 or 2. The control unit, when power supply from the commercial power supply is normally performed,
When the increase rate of the output power from the solar cell device to the DC line becomes larger than the set increase rate, the increase rate of the AC output power of the inverter becomes the set inverter output increase rate from the DC line. Implement output increase suppression control to control the operation of the third power converter so as to charge the power storage device,
The output increase suppression control is stopped when the increase rate of output power from the solar cell device to the DC line becomes smaller than the set increase rate in the state where the output increase suppression control is being performed. The electric power supply system as described in any one of 1-3. The control unit, when power supply from the commercial power supply is normally performed,
The third power converter is configured to charge the power storage device when the power storage device is not charged / discharged and the power storage amount of the power storage device is less than a maximum value and the power generation device has an output margin. The electric power supply system as described in any one of Claims 1-4 which controls operation | movement. The switch is composed of a semiconductor switch circuit,
The said control part will operate the said switch, if it determines with the power failure having generate | occur | produced in the said commercial power supply, The connection between the said commercial power supply and the alternating current side of the said inverter will be interrupted | blocked. The power supply system according to item. The control unit, when a power failure occurs in the commercial power supply,
Controlling the operation of the power generator and the first power converter so that the voltage of the DC line becomes a set DC voltage at the time of a power failure, and
Controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized; and
The power supply system according to claim 6, wherein the operation of the inverter is controlled so that the voltage of the AC line becomes a set AC voltage during a power failure. The control unit, when a power failure occurs in the commercial power supply,
Performing voltage maintenance control for controlling the operation of the third power converter so that the voltage of the DC line becomes the DC voltage set at the time of power failure,
The power storage device is charged when the voltage maintenance control is not performed and the power storage amount of the power storage device is less than a maximum value and the power generation device and / or the solar cell device has an output margin. The power supply system according to claim 6 or 7, wherein the operation of the third power converter is controlled. The control unit, when a power failure occurs in the commercial power supply,
When operating the power generator, controlling the operation of the second power converter so that the output power from the solar cell device to the DC line is maximized, and
The power supply system according to claim 6, wherein when the power generation device is not operated, the operation of the second power converter is controlled so that the voltage of the DC line becomes a set DC voltage during a power failure.

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