JP5297127B2 - DC power supply system and power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC power feeding system in which a voltage of a DC bus bar can be maintained using a power storage device even at both normal power supply and power failure of a commercial power system. <P>SOLUTION: By a control means 14, the operation of a rectifier 2 is controlled so that the voltage of the DC bus bar 4 becomes a reference voltage in system linkage when the voltage of the commercial power system 3 satisfies a normal operation condition, the power storage device 1 is charged and operated when the voltage of the DC bus bar 4 is equal to or more than an upper limit voltage in the system linkage which is higher than the reference voltage in the system linkage, and the power storage device 1 is discharged and operated when the voltage of the DC bus bar 4 is equal to or less than a lower limit voltage in the system linkage which is lower than the reference voltage in the system linkage. At the same time, the operation of the rectifier 2 is stopped when the voltage of the commercial power system 3 does not satisfy a predetermined normal operation condition, the power storage device 1 is charged and operated when the voltage of the DC bus bar 4 is higher than the reference voltage in independent operation, and the power storage device 1 is discharged and operated when the voltage of the DC bus bar 4 is lower than the reference voltage in the independent operation. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a DC power supply system including a DC bus in which a plurality of power consuming units and a plurality of power supply units are commonly connected, and a commercial power system is connected via a rectifier, and such a DC power supply system. The present invention relates to a power storage device used in.

  In a DC power supply system including a DC bus connected to a plurality of power consuming units and a plurality of power supply units in common and connected to a commercial power system via a rectifier, a power storage device is connected to the DC bus. There is something. For example, in the DC power supply system described in Patent Document 1, the voltage of the DC bus is a constant voltage (DC voltage Vdc) using power from a commercial power system connected via a rectifier and power from a power storage device. Maintained. Specifically, the voltage of the DC bus that is the control target of the rectifier and the voltage of the DC bus that is the control target of the power storage device are the same.

Japanese Patent Laying-Open No. 2005-224209 (FIG. 1, paragraph 0010)

  In the DC power supply system described in Patent Document 1, when the DC bus is connected to the commercial power system via the rectifier, the power storage device plays a role of maintaining the voltage of the DC bus as in the rectifier. Yes. When the power storage device is operated in this manner, the power storage device operates mainly for maintaining the voltage of the DC bus, and therefore the charge rate is not always maintained at an appropriate value. Therefore, when a power failure occurs in the commercial power system, only the power storage device has to play the role of maintaining the voltage of the DC bus, but it cannot play the role if the charging rate is not appropriate.

  The present invention has been made in view of the above-described problems, and the object thereof is to maintain the voltage of the DC bus using the power storage device during both a power failure and a non-power failure of the commercial power system. The object is to provide a DC power supply system and a power storage device used in such a DC power supply system.

In order to achieve the above object, the DC power supply system according to the present invention includes a plurality of power consumption units, a plurality of power supply units, a power storage device, and a commercial power system that are commonly connected to a DC bus. A rectifier that converts the AC power supplied from the DC power into the DC bus, and a control unit that controls the operation of the power storage device and the rectifier.
The control means includes
When the voltage of the commercial power system satisfies a normal operation condition for determining whether or not sufficient power can be supplied from the commercial power system to the DC bus, the voltage of the DC bus is connected Controlling the operation of the rectifier so as to be a voltage, charging the power storage device when the voltage of the DC bus is equal to or higher than the connection time upper limit voltage greater than the connection time reference voltage, and the DC bus When the voltage is less than the connection time lower limit voltage less than the connection time reference voltage, the storage device is discharged, and
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the operation of the rectifier is stopped, and the power storage device is charged when the voltage of the DC bus is larger than the reference voltage during the independent operation, and The power storage device is configured to discharge when the voltage of the DC bus is smaller than the reference voltage during the self-sustaining operation.

According to the above characteristic configuration, when the voltage of the commercial power system satisfies the normal operating condition by normally supplying power from the commercial power system, the voltage of the DC bus is connected to the reference time by operating the rectifier. Can be controlled to voltage. In addition, when the load by the power consumption unit increases so rapidly that the power supplied via the rectifier and the power supplied from the operating power supply unit cannot be covered, or the load by the power consumption unit When the voltage of the DC bus becomes equal to or higher than the upper limit voltage at the time of connection and lower than the lower limit voltage at the time of connection due to a case where the power supply is rapidly reduced to less than or equal to the power supplied from the supply unit, The voltage of the DC bus can be controlled to the upper limit voltage during interconnection or the lower limit voltage during interconnection. In other words, the voltage of the DC bus is controlled to be higher than the upper limit voltage at the time of connection or lower than the lower limit voltage at the time of connection using the power storage device while controlling the voltage of the DC bus to the reference voltage during connection using a rectifier. Is suppressed.
On the other hand, when the electric power is not normally supplied from the commercial power system, the voltage of the DC bus can be controlled to the reference voltage during the self-sustaining operation by charging or discharging the power storage device.
Therefore, it is possible to provide a direct current power supply system capable of maintaining the voltage of the direct current bus using the power storage device during both a power failure and a non-power failure of the commercial power system.

  Another characteristic configuration of the DC power supply system according to the present invention is that the reference voltage during the self-sustained operation is equal to or higher than the connection time lower limit voltage and lower than the connection time upper limit voltage.

  According to the above characteristic configuration, even when power is not normally supplied from the commercial power system due to a power failure or the like, the voltage of the DC bus is in the same range as when power is normally supplied from the commercial power system. (That is, a voltage not lower than the connection time lower limit voltage and lower than the connection time upper limit voltage).

  According to another characteristic configuration of the DC power supply system according to the present invention, the control means is configured such that the voltage of the commercial power system satisfies the normal operation condition, and the voltage of the DC bus is larger than the lower limit voltage at the time of interconnection. When the power storage amount of the power storage device is smaller than a set lower limit value when the power storage device is smaller than the upper limit voltage at the time of interconnection, the power storage device is switched to a charging operation, and when the power storage amount of the power storage device is larger than a set upper limit value, the power storage device is The point is to switch to discharge operation.

  According to the above characteristic configuration, when the voltage of the commercial power system satisfies the normal operation condition by normally supplying power from the commercial power system, the voltage of the DC bus is larger than the connection time lower limit voltage and the above When the voltage is lower than the upper limit voltage at the time of interconnection, since the voltage of the DC bus is appropriately maintained by the rectifier, the power storage device does not have to operate to maintain the voltage of the DC bus. Therefore, the control unit switches the power storage device to the charging operation when the power storage amount of the power storage device becomes smaller than the set lower limit value, and switches the power storage device to the discharge operation when the power storage amount of the power storage device becomes larger than the set upper limit value. Can be maintained between the set lower limit and the set upper limit. As a result, even if a power failure occurs in the commercial power system after that, the voltage of the DC bus can be maintained using the power storage device.

Another characteristic configuration of the DC power supply system according to the present invention is a plurality of power generators in which the plurality of power supply units are controlled to be in an operation state or a stop state between a set minimum output and a set maximum output,
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the control means,
When the power storage device is charged, the total power supply amount of the plurality of power generation devices is larger than the total power consumption amount of the plurality of power consumption units by an amount equal to or less than the set maximum output. Control the number of units in operation, and
When discharging the power storage device, the total power supply amount of the plurality of power generation devices is smaller than the total power consumption amount of the plurality of power consumption units by an amount equal to or less than the set maximum output of the power generation device, The point is to control the number of operating power generators.

  According to the above characteristic configuration, the number of operating power generators is adjusted such that the difference between the total power consumption and the total power supply amount, that is, the charge / discharge amount is equal to or less than the set maximum output of the power generator. As a result, excessive charging / discharging of the power storage unit can be avoided.

In order to achieve the above object, the power storage device according to the present invention is characterized in that a plurality of power consuming units and a plurality of power supply units are commonly connected to a DC bus, and a commercial power system is connected to the DC bus via a rectifier. And the rectifier satisfies a normal operation condition for determining whether or not the voltage of the commercial power system can supply sufficient power from the commercial power system to the DC bus. voltage of the DC bus is operated so that the reference voltage at the interconnection, and a DC power supply system voltage of the commercial power system is configured to stop the operation in the case that does not satisfy the normal operating conditions used is, a power storage unit connected to said DC bus, control for controlling the discharge operation from the DC bus to the DC bus from the charging operation and the power storage unit to the power storage unit A power storage apparatus and means,
The control means includes
In the case where the voltage of the commercial power system satisfies the normal operation condition, when the voltage of the DC bus is equal to or higher than the connection time upper limit voltage greater than the connection time reference voltage, the power storage unit is charged. When the voltage of the DC bus is equal to or lower than the connection time lower limit voltage lower than the connection time reference voltage, the power storage unit is discharged, and
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the power storage unit is charged when the voltage of the DC bus is larger than the reference voltage during the independent operation, and the voltage of the DC bus is the independent operation When the voltage is smaller than the hour reference voltage, the power storage unit is discharged.

According to the above characteristic configuration, when the rectifier controls the voltage of the DC bus to the connected reference voltage, the load by the power consumption unit is supplied from the power supplied via the rectifier and the operating power supply unit. If the power supply unit suddenly increases beyond the power supplied, or if the load of the power consuming unit suddenly decreases below the power supplied from the power supply unit, etc. When the voltage is higher than the voltage and lower than the lower limit voltage at the time of connection, the voltage of the DC bus can be controlled to the upper limit voltage at the time of connection or the lower limit voltage at the time of connection by operating the power storage device to perform charging operation or discharging operation. In other words, while the rectifier plays the role of controlling the DC bus voltage to the connection time reference voltage, the DC bus voltage becomes larger than the connection time upper limit voltage or the connection time lower limit voltage using the power storage device. It is suppressed from becoming smaller.
On the other hand, when the electric power is not normally supplied from the commercial power system, the voltage of the DC bus can be controlled to the reference voltage during the self-sustaining operation by charging or discharging the power storage device.
Therefore, it is possible to provide a power storage device that can maintain the voltage of the DC bus in both cases of a power failure and a non-power failure of the commercial power system.

  Another characteristic configuration of the power storage device according to the present invention is that the reference voltage at the time of self-sustained operation is equal to or higher than the lower limit voltage at the time of interconnection and lower than the upper limit voltage at the time of linkage.

  According to the above characteristic configuration, even when power is not normally supplied from the commercial power system due to a power failure or the like, the voltage of the DC bus is in the same range as when power is normally supplied from the commercial power system. (That is, a voltage not lower than the connection time lower limit voltage and lower than the connection time upper limit voltage).

  Another characteristic configuration of the power storage device according to the present invention is that the control means includes a voltage of the commercial power system that satisfies the normal operation condition, a voltage of the DC bus is greater than the lower limit voltage at the time of interconnection, and When the power storage amount of the power storage unit is smaller than a set lower limit value, the power storage unit is switched to a charging operation when the power storage amount of the power storage unit is smaller than a set upper limit value. The point is to switch to operation.

  According to the above characteristic configuration, when the voltage of the commercial power system satisfies the normal operation condition by normally supplying power from the commercial power system, the voltage of the DC bus is larger than the connection time lower limit voltage and the above When the voltage is lower than the upper limit voltage at the time of interconnection, since the voltage of the DC bus is appropriately maintained by the rectifier, the power storage device does not have to operate to maintain the voltage of the DC bus. Therefore, the control unit switches the power storage device to the charging operation when the power storage amount of the power storage device becomes smaller than the set lower limit value, and switches the power storage device to the discharge operation when the power storage amount of the power storage device becomes larger than the set upper limit value. Can be maintained between the set lower limit and the set upper limit. As a result, even if a power failure occurs in the commercial power system after that, the voltage of the DC bus can be maintained using the power storage device.

<First Embodiment>
Hereinafter, a DC power supply system according to a first embodiment and a power storage device used in the DC power supply system will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a DC power supply system S1 according to the first embodiment. As shown in the figure, the DC power supply system S1 is commonly connected to the DC bus 4 and includes power consumption devices 12 and 13 as a plurality of power consumption units, a power generation device 9 and a power storage as a plurality of power supply units. The apparatus 1 includes a rectifier 2 that converts AC power supplied from the commercial power system 3 into DC power and supplies the DC power to the DC bus 4, and a control unit 14 that controls the operation of the power storage device 1 and the rectifier 2. The rectifier 2 is connected to the commercial power system 3 via the circuit breaker 5. In this embodiment, the case where a power consumption unit is comprised with the power consumption apparatus 12 as an alternating current load and the power consumption apparatus 13 as a direct current load is illustrated. The power consuming apparatus 12 is connected to the DC bus 4 via the inverter 11 and receives supply of AC power. The power consuming device 13 is connected to the DC bus 4 and is supplied with DC power.

  The power generation device 9 is configured using a DC power generation device or an AC power generation device. Examples of the DC power generator include a fuel cell. Moreover, as an AC power generator, there is a gas engine power generator using a driving force of a gas engine. When the power generation device 9 is a DC power generation device, the power generation device 9 is connected to the DC bus 4 via a power converter 8 such as a DC / DC converter. When the power generation device 9 is an AC power generation device, the power generation device is connected to the DC bus 4 via a power converter 8 such as a rectifier.

  Each of the fuel cell and the gas engine power generator is a combined heat and power device capable of generating heat and electricity together. In this embodiment, since it is assumed that the fuel cell and the gas engine power generator are used as the power generator 9, the heat consuming device 10 that consumes the heat supplied from the power generator 9 is provided. Examples of the heat consuming device 10 include a hot water supply device and a heating device. A hot water storage device that stores the thermal energy recovered from the power generation device 9 in the form of hot water can also be considered as an example of the heat consuming device 10.

The power storage device 1 includes at least one of a chemical battery, a capacitor, and a flywheel. In the present embodiment, a configuration in which an electric double layer capacitor 1b (EDLC) as the power storage device 1 is connected to the DC bus 4 via the DC / DC converter 1a is illustrated. Therefore, the amount of electricity stored in the power storage device 1 corresponds to the voltage between the output terminals of the capacitor 1b (hereinafter also referred to as “capacitor voltage: V _EDLC ”).

  In the present embodiment, the control target of the DC power supply system S1 is to supply sufficient power to the power consuming devices 12 and 13. Therefore, the control means 14 controls at least the operation of the power storage device 1 and the rectifier 2 so that the voltage of the DC bus 4 becomes an appropriate value.

  Next, with reference to the flowcharts shown in FIGS. 2 to 4, operation control of the power storage device 1, the rectifier 2, and the power generation device 9 by the control unit 14 will be described. FIG. 2 is a flowchart showing control when the DC power feeding system S1 is switched to the interconnection operation mode or the independent operation mode depending on whether or not the commercial power system 3 is normal. FIG. 3 is a flowchart of control performed by the DC power supply system S1 in the interconnected operation mode, and FIG. 4 is a flowchart of control performed by the DC power supply system S1 in the independent operation mode. .

  As shown in FIG. 2, in step # 10, the control means 14 determines whether or not the voltage of the commercial power system 3 satisfies the normal operation condition. The normal operation condition is a condition for determining whether or not sufficient power can be supplied from the commercial power system 3 to the DC bus 4. In the present embodiment, the control unit 14 monitors the voltage of the commercial power system 3 using the voltmeter 6. Then, the control means 14 determines that the normal operation condition is satisfied when the period during which the voltage of the commercial power system 3 is maintained at a predetermined determination voltage or more continues for two cycles of the AC voltage, and the process proceeds to step # 20. The operation of the DC power feeding system S1 is controlled by the interconnection operation mode control described later. On the other hand, if the period during which the voltage of the commercial power system 3 is lower than the determination voltage continues for two cycles of the AC voltage, the control unit 14 determines that the normal operation condition is not satisfied, and proceeds to step # 30. Then, the operation of the DC power feeding system S1 is controlled by the self-sustaining operation mode control described later. Moreover, the control means 14 can also carry out the circuit breaker operation of the circuit breaker 5 when the voltage of the commercial power system 3 does not satisfy the normal operation condition.

[Linked operation mode control]
When the voltage of the commercial power system 3 satisfies the normal operation condition, that is, when the sufficient power can be supplied from the commercial power system 3 to the DC bus 4, the control unit 14 performs the interconnected operation illustrated in FIG. 3. The operation of the DC power supply system S1 is controlled by mode control. Hereinafter, the interconnection operation mode control will be described with reference to FIG.

When the interconnection operation mode control is being performed, the control unit 14 allows the power generation device 9 to perform an operation that generates a heat amount corresponding to the heat demand of each heat consuming device 10. That is, the electric power supplied from each power generator 9 to the DC bus 4 is not controlled and varies. However, the control means 14 controls the operation of the rectifier 2 so that the voltage of the DC bus 4 becomes the reference voltage at the time of _connection : V _{DC_ref} in the _connection operation mode control. Therefore, regardless of the operating state of each power generator 9, the voltage of the DC bus 4 does not deviate significantly from the reference voltage _{VDC_ref} during interconnection.

However, if the power consumption in the power consuming devices 12 and 13 suddenly rises or falls, or the power generation device 9 suddenly rises or falls, the voltage control in the rectifier 2 is not in time, and the DC bus voltage: _VDC is There is a possibility that it is significantly _different from the reference voltage at the time of interconnection: V _{DC_ref} . Therefore, the control means 14 confirms the value of DC bus voltage: _VDC with reference to the monitoring result of the voltmeter 7 which measures the voltage of the DC bus 4 in step # 21.
When the DC bus voltage: V _DC is _{equal to} or lower than the _connection time lower limit voltage: V _{DC_LL} , the control means 14 _proceeds to step # 22 and supplies power from the capacitor 1b to the DC bus 4. Specifically, the control means 14 operates the capacitor 1b in the discharge mode so that the DC bus voltage: _VDC does not fall below the _connection time lower limit voltage: _{VDC_LL} .
On the other hand, when the DC bus voltage: _VDC is _{equal to} or higher than the upper limit voltage: V _{DC_UL} at the time of connection, the control unit 14 _proceeds to step # 23 and recovers power from the DC bus 4 by the capacitor 1b. Specifically, the control means 14 operates the capacitor 1b in the charging mode so that the DC bus voltage: V _DC does not exceed the upper limit voltage: V _{DC_UL} during interconnection.
When the control means 14 performs the control as described above, the DC bus voltage: V _DC is stable at _least within a range lower than the _connection time lower limit voltage: V _{DC_LL and} lower than the _connection time upper limit voltage: V _{DC_UL.} To do. However, in this embodiment, V _{DC_LL} <V _{DC_ref} <V _{DC_UL} .

When the control means 14 determines in step # 21 that the DC bus voltage: V _DC is in a _range greater than the _connection time lower limit voltage: V _{DC_LL and} less than the _connection time upper limit voltage: V _{DC_UL} , Move to # 24. Here, the fact that the DC bus voltage: V _DC is in a range larger than the _connection time lower limit voltage: V _{DC_LL and} less than the _connection time upper limit voltage: V _{DC_UL} is the voltage control of the DC bus 4 by the rectifier 2. This means that the capacitor 1b does not need to be used for voltage control of the DC bus 4. Therefore, the control means 14 maintains the charge amount of the capacitor 1b within an appropriate range (set lower limit value: V _{IC_LL} or more and set upper limit value: V _{IC_UL} or less) regardless of the voltage control of the DC bus 4. For the purpose, the capacitor 1b is charged or discharged. In other words, even if the voltage of the DC bus 4 suddenly fluctuates, the control means 14 uses the capacitor device V _EDLC so that the voltage of the DC bus 4 can be kept appropriate by operating the power storage device 1 at that time. It should be within the set voltage range _not less than the set lower limit voltage value V _{IC_LL} and _not more than the set upper limit voltage value V _{IC_UL} .

Specifically, in step # 24, the control unit 14 verifies the value of the capacitor voltage: V _EDLC measured using a voltmeter (not shown). Then, when the capacitor voltage: V _EDLC becomes smaller than the set lower limit value: V _{IC_LL} , the control means 14 _proceeds to step # 25 and switches to the charging mode so that the capacitor 1b is charged. On the other hand, when the capacitor voltage: V _EDLC becomes larger than the set upper limit value: V _{IC_LL} , the control unit 14 _proceeds to step # 26 and switches to the discharge mode so that the capacitor 1b is discharged. If the capacitor voltage: V _EDLC is not _less than the set lower limit value: V _{IC_LL} and not _less than the set upper limit value: V _{IC_UL} , the control means 14 does not switch the mode and maintains the current charge mode or discharge mode.

  The control means 14 returns to the control flow shown in FIG. 2 when the above-described interconnection operation mode control is completed. Then, the control unit 14 determines again whether or not the voltage of the commercial power system 3 satisfies the normal operation condition in the control flow shown in FIG.

[Independent operation mode control]
When the voltage of the commercial power system 3 does not satisfy the normal operation condition, that is, when the sufficient power cannot be supplied from the commercial power system 3 to the DC bus 4, the control means 14 is a self-sustained operation mode illustrated in FIG. The operation of the DC power supply system S1 is controlled by the control. Hereinafter, the independent operation mode control will be described with reference to FIG.

In this case, since power is not supplied from the commercial power system 3 to the DC bus 4, the rectifier 2 cannot be controlled so that the DC bus voltage: V _{DC becomes the connection} time reference voltage: V _{DC_ref} . Therefore, the control means 14 uses the electric power discharged from the capacitor 1b to the DC bus 4 and the electric power charged by the capacitor 1b from the DC bus 4, so that the DC bus voltage: V _{DC becomes the} interconnection reference voltage: V _{DC_ref.} The operation of the capacitor 1b is controlled.

In step # 31, the control means 14 refers to the monitoring result of the voltmeter 7 that measures the voltage of the DC bus 4, and checks the value of DC bus voltage: _VDC . The control means 14 controls the charging / discharging of the capacitor 1b so that V _DC = V _{DC_ref} when the DC bus voltage: V _DC deviates from the reference voltage during independent operation: V _{DC_ref} . Specifically, when the DC bus voltage: V _DC is smaller than the reference voltage during independent operation: V _{DC_ref} , the control unit 14 _proceeds to step # 32 and discharges the capacitor 1b so that V _DC = V _{DC_ref.} Operate in mode. On the other hand, when the DC bus voltage: V _DC is larger than the reference voltage during independent operation: V _{DC_ref} , the control means 14 _proceeds to step # 33 and _{sets the} capacitor 1b in the charging mode so that V _DC = V _{DC_ref.} Operate.
In the present embodiment, the reference voltage at the time of _{grid connection} and the reference voltage at the time of independent operation are set to be the same by V _{DC_ref} . Therefore, the voltage of DC bus 4 can be controlled to the same voltage when power is normally supplied from commercial power system 3 and when power is not normally supplied from commercial power system 3 due to a power failure or the like. However, the reference voltage at the time of self-sustained operation may be set to a voltage that is equal to or higher than the connection time lower limit voltage and lower than the connection time upper limit voltage. Then, even when power is not normally supplied from the commercial power system 3 due to a power failure or the like, the voltage of the DC bus 4 is set to the same level as when power is normally supplied from the commercial power system 3. (That is, the voltage can be controlled to be higher than the lower limit voltage at the time of interconnection and lower than the upper limit voltage at the time of interconnection).

  In addition, since sufficient power is not supplied from the commercial power system 3 to the DC bus 4, the power supplied from the power generator 9 to the DC bus 4 and the power consumed by the power consuming devices 12 and 13 are greatly different from each other. This inevitably increases the amount of charge or discharge of the capacitor 1b. Therefore, the control means 14 performs the operation of at least one of the power consuming devices 12 and 13 and the power generator 9 so that the output (charge amount or discharge amount) from the capacitor 1b is in an appropriate range in the self-sustained operation mode control. Control.

  Specifically, in step # 34, the control means 14 determines whether or not the output from the capacitor 1b is within a set range not less than the set lower limit output value and not more than the set upper limit output value. Here, the output from the capacitor 1 b is a value obtained by subtracting the total power supply amount of the plurality of power generation devices 9 from the total power consumption amount of the plurality of power consumption devices 12 and 13. Therefore, if the output from the capacitor 1b is a positive value, it means that the capacitor 1b is discharged, and if the output from the capacitor 1b is a negative value, it means that the capacitor 1b is charged. To do.

  Therefore, when operating the capacitor 1b in the charging mode set in step # 33, the control unit 14 uses the total power consumption of the plurality of power consuming devices 12 and 13 so that the capacitor 1b is charged. The operation of at least one of the power consumption devices 12 and 13 and the power generation device 9 is controlled so that the total power supply amount of the plurality of power generation devices 9 is increased. In addition, when operating the capacitor 1b in the discharge mode set in step # 32, the control unit 14 uses the total power consumption of the plurality of power consuming devices 12, 13 so that the capacitor 1b is discharged. The operation of at least one of the power consumption devices 12 and 13 and the power generation device 9 is controlled so that the total power supply amount of the plurality of power generation devices 9 is reduced.

When the power generation output is variable, the power generation device 9 is controlled to be in an operation state or a stop state between the set minimum output and the set maximum output. Alternatively, when the power generation output of the power generation device 9 is not variable (that is, in the above-described case, the set minimum output and the set maximum output are regarded as the same value), the power generation device 9 has a rated output (= set minimum output = set It is controlled to the operation state or the stop state at the maximum output).
In the following description, a case where the power generation output of the power generation device 9 is not variable will be exemplified. In this case, the power generation device 9 is either operated at the rated output or stopped, and the case where the rated output of the power generation device 9 is 300 W is exemplified. Therefore, the electric power that each of the power generation devices 9 can output is 0 W or 300 W.
Therefore, in order to make the total power supply amount larger than the total power consumption amount, the control unit 14 may start several power generators 9 and increase the total power supply amount. Moreover, the control means 14 should just stop several power generators 9 and make a total power supply amount small, so that a total power supply amount may become smaller than a total power consumption.

Thus, in the discharge mode, when the output P _EDLC from the capacitor 1b is P _EDLC > 300 W (hereinafter, for simplicity, the unit W is omitted in the inequality of P _EDLC ), the power generator 9 having a rated output of 300 W When one or a plurality of are started, the output from the capacitor 1b becomes 0 ≦ P _EDLC ≦ 300.
Further, in the charging mode, when the output P _EDLC from the capacitor 1b is P _EDLC <−300, if one or more power generation devices 9 having a rated output of 300 W are stopped, the output from the capacitor 1b is −300. ≦ P _EDLC ≦ 0.

As described above, in step # 34, the control means 14 determines whether or not −300 ≦ P _EDLC ≦ 0 in the charge mode, and whether or not 0 ≦ P _EDLC ≦ 300 in the discharge mode. Judgment is made. When the P _EDLC exceeds the upper limit value (that is, when 0 <P _EDLC in the charge mode and when P _EDLC > 300 in the discharge mode), the control unit 14 _proceeds to step # 37. . That is, when the amount of charge to the capacitor 1b is insufficient in the charge mode, the number of operating power generators 9 is increased to increase the amount of charge to the capacitor 1b. Further, when the discharge amount from the capacitor 1b is excessive in the discharge mode, the number of operating power generators 9 is increased to reduce the discharge amount from the capacitor 1b.

In addition, when the P _EDLC exceeds the lower limit value (that is, when P _EDLC <−300 in the charge mode and when P _EDLC <0 in the discharge mode), the control unit 14 performs step # 35. That is, when the amount of charge to the capacitor 1b is excessive in the charge mode, the number of operating power generators 9 is decreased to reduce the amount of charge to the capacitor 1b. Further, when the discharge amount from the capacitor 1b is insufficient in the discharge mode, the number of operating power generators 9 is decreased in order to increase the discharge amount from the capacitor 1b.

On the other hand, the control means 14 is such that when P _EDLC is between the lower limit value and the upper limit value (that is, −300 ≦ P _EDLC ≦ 0 in the charge mode and 0 ≦ P _EDLC ≦ 300 in the discharge mode). If there is, the process proceeds to step # 39.

That is, when the control unit 14 charges the capacitor 1b (power storage device 1), the total power supply amount of the power generation device 9 is less than the rated output of the power generation device 9 (or the set maximum output when the power generation output is variable). Only when the number of operating power generators 9 is controlled to be larger than the total power consumption of the power consuming devices 12 and 13 and when the power storage device 1 is discharged, the total power supply amount of the power generating devices 9 is the power generating device. The number of operating power generators 9 is controlled so as to be smaller than the total power consumption of the power consuming devices 12 and 13 by an amount equal to or less than the rated output of 9 (or the set maximum output when the power generation output is variable).
In the present embodiment, the control unit 14 determines that the output P _EDLC from the capacitor 1b is 0 ≦ P _EDLC ≦ 300 in the discharge mode when the rated output of each of the power generation devices 9 whose power generation output is not variable is 300 _W. In this way, the number of operating power generators 9 is controlled, and in the charging mode, the number of operating power generators 9 is controlled so that −300 ≦ P _EDLC ≦ 0. As a result, excessive discharge or charging can be prevented.

In step # 35, the control means 14 determines whether or not at least one power generator 9 can be stopped. When it is possible to stop at least one power generator 9, the control means 14 proceeds to step # 36 and stops, and when it cannot be stopped, it proceeds to step # 39.
In step # 37, the control means 14 determines whether or not at least one power generator 9 can be started. When it is possible to start at least one power generator 9, the control means 14 proceeds to step # 38 and starts, and when it cannot be started, it proceeds to step # 39.
In step # 39, the control unit 14 does not newly start and stop the power generation device 9 in order to maintain the operation state of the power generation device 9.

  In the flowchart of FIG. 4, by controlling the operation of the power consuming devices 12 and 13, the total power supply amount becomes smaller than the total power consumption amount or the total power supply amount becomes larger than the total power consumption amount. It may be made to become. In that case, in process # 35-process # 39, it should just modify so that the power consumption of the power consuming apparatuses 12 and 13 may be changed, with the operating state of the electric power generating apparatus 9 as it is.

Second Embodiment
The DC power supply system of the second embodiment is different from the DC power supply system shown in the first embodiment in that each of the power storage device and the rectifier is configured to be independent and control the operation. Hereinafter, the configuration of the DC power supply system and the power storage device of the second embodiment will be described, but the description of the same configuration as that of the first embodiment will be omitted.

FIG. 5 is a diagram illustrating the configuration of the DC power supply system S2 of the second embodiment.
In the present embodiment, the rectifier 2 includes a rectifier circuit 2a and a control means 2b. This control means 2b controls only the operation of the rectifier 2 independently. Specifically, the control means 2b refers to the measurement results of the voltmeter 6 and the voltmeter 7, and when the voltage of the commercial power system 3 satisfies the normal operation condition, the voltage of the DC bus 4: _VDC is interconnected. The rectifier circuit 2a is operated so that the time reference voltage becomes V _{DC_ref} , and the operation of the rectifier circuit 2a is stopped when the voltage of the commercial power system 3 does not satisfy a predetermined normal operation condition.
That is, when the rectifier 2 can supply sufficient power from the commercial power system 3 to the DC bus 4, the rectifier 2 uses the power supplied from the commercial power system 3 to connect the voltage: _VDC of the DC bus 4. The operation of the rectifier circuit 2a is controlled so that the time reference voltage is V _{DC_ref} . On the other hand, the rectifier 2 stops its operation when sufficient power cannot be supplied from the commercial power system 3 to the DC bus 4.
The determination performed by the control means 2b of the rectifier 2 as to whether or not the voltage of the commercial power system 3 satisfies the normal operation condition is the same as in the first embodiment.

The power storage device 1 has a configuration in which a capacitor 1b as a power storage unit is connected to the DC bus 4 via a DC / DC converter 1a, and the operation of the DC / DC converter 1a is controlled by a control means 1c provided in the power storage device 1. The That is, the control unit 1c controls the operation of the DC / DC converter 1a, whereby the charging operation and the discharging operation of the capacitor 1b are controlled. The control means 1c refers to the measurement results of the voltmeter 6 and the voltmeter 7, and when the voltage of the commercial power system 3 satisfies the normal operation condition, the control means 1c is connected to the DC bus 4 whose voltage is higher than the connection time reference voltage. When the voltage is higher than the system upper limit voltage, the capacitor 1b is charged, and when the voltage of the DC bus 4 is lower than the connection time lower limit voltage than the connection time reference voltage, the capacitor 1b is discharged. Further, the control means 1c charges the capacitor 1b when the voltage of the DC power bus 4 is larger than the reference voltage during the self-sustaining operation when the voltage of the commercial power system 3 does not satisfy a predetermined normal operation condition, and the DC bus When the voltage of 4 is smaller than the reference voltage during the self-sustaining operation, the capacitor 1b is discharged.
Regarding the determination of whether or not the voltage of the commercial power system 3 satisfies the normal operation condition performed by the control unit 1c of the power storage device 1, and the relationship between the reference voltage during interconnection and the reference voltage during autonomous operation, It is the same as the form.

  In addition, the control means 1c included in the power storage device 1 is configured such that the voltage of the commercial power system 3 satisfies the normal operation condition, and the voltage of the DC bus 4 is larger than the connection time lower limit voltage and lower than the connection time upper limit voltage. , The capacitor 1b is switched to the charging operation when the charged amount of the capacitor 1b is smaller than the set lower limit value, and the capacitor 1b is switched to the discharging operation when the charged amount of the capacitor 1b is larger than the set upper limit value.

  The control means 15 of the DC power supply system S2 can also operate in conjunction with the control means 1c of the power storage device 1 and the control means 2b of the rectifier 2. For example, the control means 15 of the DC power supply system S2 may be configured such that when the power storage device 1 operates the capacitor 1b in the charging mode, the total power of the plurality of power consuming devices 12 and 13 is charged so that the capacitor 1b is charged. The operation of at least one of the power consumption devices 12 and 13 and the power generation device 9 is controlled so that the total power supply amount of the plurality of power generation devices 9 is larger than the consumption amount. In addition, when the power storage device 1 operates the capacitor 1b in the discharge mode, the control unit 15 uses a plurality of power generations based on the total power consumption of the power consumption devices 12 and 13 so that the capacitor 1b is discharged. The operation of at least one of the power consumption devices 12 and 13 and the power generation device 9 is controlled so that the total power supply amount of the device 9 is reduced.

<Another embodiment>
<1>
In the above embodiment, the criterion (normal operating condition) for determining whether the commercial power system is normal can be changed as appropriate.

<2>
In the embodiment described above, the voltage of the DC bus is kept low when power is not normally supplied from the commercial power system 3 due to a power failure or the like by setting the reference voltage for autonomous operation to a voltage lower than the reference voltage for interconnection. Thus, the discharge of the power storage device can be continued for a long time.

<3>
In the above embodiment, the number of power consuming devices, power generating devices, and power storage devices can be changed as appropriate. In addition, one power consuming unit, a power supply unit, and a power storage unit are each composed of one power consuming device, a power generation device, and a power storage device, or a plurality of power consuming devices, a power generation device, and a power storage device. There are cases where it is configured. Alternatively, the operation of multiple power generators can be simulated by changing the power supply amount of one power generator in a stepwise manner for each set output, and apparently a plurality of power supply units are configured with a single power generator. You can also

  The DC power supply system and the power storage device according to the present invention can be used for supplying sufficient power to the power consuming device while maintaining the voltage of the DC bus appropriately.

The figure explaining the structure of the DC power supply system of 1st Embodiment Flow chart showing control when switching DC power supply system to grid operation mode or self-sustaining operation mode Flow chart of control executed in DC power supply system in interconnected operation mode Flow chart of control performed in the DC power supply system in the self-sustaining operation mode The figure explaining the structure of the DC power supply system of 2nd Embodiment

Explanation of symbols

1 power storage device 1c control means 1b power storage unit (capacitor)
2 Rectifier 3 Commercial Power System 4 DC Bus 9 Power Generator (Power Supply Unit)
12, 13 Power consumption device (power consumption unit)
14 Control means S1, S2 DC power supply system

Claims (7)

A plurality of power consumption units, a plurality of power supply units and a power storage device connected in common to the DC bus, and AC power supplied from a commercial power system is converted to DC power and supplied to the DC bus A rectifier, and a control means for controlling the operation of the power storage device and the rectifier,
The control means includes
When the voltage of the commercial power system satisfies a normal operation condition for determining whether or not sufficient power can be supplied from the commercial power system to the DC bus, the voltage of the DC bus is connected Controlling the operation of the rectifier so as to be a voltage, charging the power storage device when the voltage of the DC bus is equal to or higher than the connection time upper limit voltage greater than the connection time reference voltage, and the DC bus When the voltage is less than the connection time lower limit voltage less than the connection time reference voltage, the storage device is discharged, and
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the operation of the rectifier is stopped, and the power storage device is charged when the voltage of the DC bus is larger than the reference voltage during the independent operation, and A DC power supply system configured to discharge the power storage device when a voltage of the DC bus is smaller than a reference voltage during the self-sustaining operation.   2. The DC power supply system according to claim 1, wherein the reference voltage at the time of self-sustained operation is equal to or higher than the lower limit voltage during interconnection and equal to or lower than the upper limit voltage during interconnection.   In the case where the voltage of the commercial power system satisfies the normal operation condition and the voltage of the DC bus is larger than the lower limit voltage at the time of connection and lower than the upper limit voltage at the time of connection, the control means The DC power feeding system according to claim 1 or 2, wherein the power storage device is switched to a charging operation when a power storage amount of the power storage device is smaller than a set lower limit value, and the power storage device is switched to a discharge operation when the power storage amount of the power storage device is larger than a set upper limit value. . The plurality of power supply units are a plurality of power generators controlled to be in an operation state or a stop state between a set minimum output and a set maximum output,
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the control means,
When charging the power storage device, the total power supply amount of the plurality of power generation devices is larger than the total power consumption amount of the plurality of power consumption units by an amount equal to or less than the set maximum output of the power generation device. Controlling the number of operating power generators; and
When discharging the power storage device, the total power supply amount of the plurality of power generation devices is smaller than the total power consumption amount of the plurality of power consumption units by an amount equal to or less than the set maximum output of the power generation device, The DC power supply system according to claim 3, wherein the number of operating power generators is controlled. A plurality of power consuming units and a plurality of power supply units are commonly connected to the DC bus, and a commercial power system is connected to the DC bus via a rectifier, and the rectifier has a voltage of the commercial power system, When the normal operating condition for determining whether or not sufficient power can be supplied from the commercial power system to the DC bus, it operates so that the voltage of the DC bus becomes the reference voltage during interconnection, and the voltage of the commercial electric power system is used in a DC power supply system is configured to stop the operation in the case that does not satisfy the normal operating condition, a power storage unit that is connected to the DC bus, from the DC bus A power storage device comprising: a control unit that controls a charging operation to the power storage unit and a discharge operation from the power storage unit to the DC bus;
The control means includes
In the case where the voltage of the commercial power system satisfies the normal operation condition, when the voltage of the DC bus is equal to or higher than the connection time upper limit voltage greater than the connection time reference voltage, the power storage unit is charged. When the voltage of the DC bus is equal to or lower than the connection time lower limit voltage lower than the connection time reference voltage, the power storage unit is discharged, and
In the case where the voltage of the commercial power system does not satisfy the normal operation condition, the power storage unit is charged when the voltage of the DC bus is larger than the reference voltage during the independent operation, and the voltage of the DC bus is the independent operation A power storage device that discharges the power storage unit when the time is less than the reference voltage.   The power storage device according to claim 5, wherein the reference voltage at the time of self-sustained operation is equal to or higher than the lower limit voltage during interconnection and equal to or lower than the upper limit voltage during interconnection.   In the case where the voltage of the commercial power system satisfies the normal operation condition and the voltage of the DC bus is larger than the lower limit voltage at the time of connection and lower than the upper limit voltage at the time of connection, the power storage unit The power storage device according to claim 5 or 6, wherein the power storage unit is switched to a charging operation when a power storage amount of the power storage unit becomes smaller than a set lower limit value, and the power storage unit is switched to a discharge operation when the power storage amount of the power storage unit becomes larger than a set upper limit value.

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