JP2012200060A - Feeding control system and feeding control method - Google Patents

Abstract

In a power supply control system, power consumption is reduced while ensuring a predetermined power supply voltage.
A power supply control system according to an embodiment includes a power supply device, a storage battery, a voltage monitoring unit, and a charge / discharge control unit. The power feeding device feeds DC power to a load via a power feeding line. The storage battery is connected to the power supply line. The voltage monitoring unit monitors the voltage on the power supply line. The charge / discharge control unit discharges power from the storage battery to the power supply line when the monitoring voltage by the voltage monitoring unit is less than the first reference voltage, and the monitoring voltage is a second reference voltage higher than the first reference voltage. In the case of exceeding, the battery is charged with power from the power supply line.
[Selection] Figure 2

Description

  Embodiments described herein relate generally to a power supply control system and a power supply control method.

  2. Description of the Related Art A power supply device that uses solar power or a storage battery for power supply in addition to AC power from a commercial power system is known in the home. This type of device includes a grid-connected inverter that uses the power of photovoltaic power generation, a chopper circuit that charges and discharges the storage battery, and controls the charging and discharging of the storage battery while detecting the AC voltage distributed to the load. .

  In addition, a device for supplying direct current to a load in a house while applying the above-described commercial power system, solar power generation, storage battery, and the like has been developed. By supplying direct current to the house, it is possible to effectively use the power of solar power generation. However, in the case of such a power supply device, there is a concern about conversion loss (switching loss) generated in a chopper circuit responsible for charging / discharging the storage battery, charging / discharging loss of the storage battery itself, and the like.

JP 2007-300792 A JP 2009-159734 A

IEEJ Transactions D, 126, 9 (2006)

  The problem to be solved by the present invention is to provide a power supply control system and a power supply control method capable of reducing power consumption while securing a predetermined power supply voltage.

  The power supply control system according to the embodiment includes a power supply device, a storage battery, a voltage monitoring unit, and a charge / discharge control unit. The power feeding device feeds DC power to a load via a DC power supply line. The storage battery is connected to this DC power supply line via a bidirectional chopper. The voltage monitoring unit monitors the voltage on the DC power supply line. The charge / discharge control unit discharges power from the storage battery to the DC power supply line when the monitoring voltage by the voltage monitoring unit is less than the first reference voltage, and the second reference is higher than the first reference voltage. When the voltage is exceeded, the storage battery is charged with power from the DC power supply line.

The figure which shows the main structures of the electric power feeding control system which concerns on embodiment. The functional block diagram which shows the structure of the bidirectional | two-way chopper and storage battery with which the electric power feeding control system of FIG. The figure for demonstrating the relationship between the starting voltage of charging / discharging with respect to the storage battery by the bidirectional | two-way chopper of FIG. 2, and the voltage on a DC power supply line. The figure for demonstrating SOC adjustment by charge to the storage battery of FIG. The figure for demonstrating supply of the charging current at the time of SOC adjustment of FIG. The figure for demonstrating supply of the charging current at the time of the start of SOC adjustment of FIG. 5, and completion | finish. The flowchart which shows the electric power feeding control method by the electric power feeding control system of FIG.

Hereinafter, embodiments will be described with reference to the drawings.
As shown in FIG. 1, the power supply control system 1 according to the embodiment is an interconnected power supply system mainly including a power supply device 10, a bidirectional chopper 7, and a storage battery 8. The power supply device 10 is for supplying DC power to a load 12 via a DC power supply line 9, and includes a power system 2, a connected inverter 3, and a PV (Photo Voltaic) panel supplied with commercial power. A solar cell 6 and a PV chopper 5 are provided.

  The PV chopper (boost chopper) 5 takes out DC power from the solar cell 6 to boost the voltage, and supplies the boosted power to the DC power supply line 9. The interconnection inverter 3 is connected between the PV chopper 5 and the power system 2. The interconnection inverter 3 converts AC power and DC power and supplies the DC power supply line 9 and / or the power system 2 with power. Further, the interconnection inverter 3 normally controls the DC power supply voltage Vdc supplied to the DC power supply line 9 to a predetermined interconnection inverter target voltage B1 as shown in FIG.

  As shown in FIG. 1, the storage battery 8 is connected to a DC power supply line 9 via a bidirectional chopper 7. The storage battery 8 is composed of a lead storage battery, a nickel metal hydride battery, a lithium ion battery, a NAS battery, or the like. The storage battery 8 may be a power storage device such as an electric double layer capacitor. The storage battery 8 has the SOC calculation part 16, as shown in FIG. The SOC calculation unit 16 calculates SOC (State Of Charge) [%] indicating the charging rate as the current charging state of the storage battery 8 main body.

The SOC of the storage battery 8 is given by the following equation.
SOC [%] = (remaining capacity [Ah] / full charge capacity [Ah]) × 100 [%]

  As shown in FIGS. 1 and 2, the bidirectional chopper 7 is connected to a DC power supply line 9, and is connected between the DC power supply line 9 and the storage battery 8. The bidirectional chopper 7 performs charging / discharging and control of the storage battery 8 while adjusting the charge current or discharge current for the storage battery 8.

  Specifically, as shown in FIG. 2, the bidirectional chopper 7 includes a voltage monitoring unit 18, a storage information acquisition unit 17, an SOC adjustment current calculation unit 19, a threshold storage unit 20, and a (first) charge / discharge control unit. 21 and a (second) charge / discharge control unit 22. The voltage monitoring unit 18 constantly monitors the DC power supply voltage Vdc on the DC power supply line 9.

  As shown in FIG. 3, the threshold storage unit 20 includes the above-described interconnected inverter target voltage B1, bidirectional chopper charge start voltage (second reference voltage) B3, and bidirectional chopper discharge start voltage (first reference voltage). ) B2 is stored in advance. The bidirectional chopper charge start voltage B3 and the bidirectional chopper discharge start voltage B2 are determined in advance to voltage values obtained by increasing or decreasing the interconnection inverter target voltage B1 that is the center voltage by approximately ± 5%.

  As shown in FIGS. 2 and 3, the charge / discharge control unit 21 supplies power from the storage battery 8 to the DC power supply line 9 when the monitoring voltage by the voltage monitoring unit 18 is less than the bidirectional chopper discharge start voltage B2. On the other hand, when the monitoring voltage exceeds the bidirectional chopper charging start voltage B3 higher than the bidirectional chopper discharge starting voltage B2, the battery 8 is charged with power from the DC power supply line 9 while discharging.

  Here, as shown in FIGS. 2 and 3, the interconnection inverter 3 controls the DC power supply voltage Vdc fed to the DC power supply line 9 to be the interconnection inverter target voltage B <b> 1. The DC power supply voltage Vdc constantly rises and falls within a short time. For this reason, if the discharge start voltage B2 and the charge start voltage B3 are set to the same voltage value, the bidirectional chopper 7 frequently switches between charging and discharging, and the switching loss of the bidirectional chopper 7 (the bidirectional chopper 7 There are concerns about an increase in current consumption) and charge / discharge loss of the storage battery 8 itself.

  However, in the power supply control system 1 of the present embodiment, the discharge start voltage B2 and the charge start voltage B3 are widened to suppress frequent switching between charge and discharge in the bidirectional chopper 7. Thus, it is possible to reduce power consumption by the bidirectional chopper 7 and the storage battery 8 while securing a predetermined power supply voltage.

  The power storage information acquisition unit 17 acquires information on the amount of power storage for the storage battery 8 from the storage battery 8 and the home energy management unit 14. Here, the in-home energy management unit 14 is realized by a so-called HEMS (Home Energy Management System). The in-home energy management unit 14 has an SOC command unit 15. The SOC command unit 15 acquires the current SOC (A1) from the storage battery 8 as shown in FIG. Furthermore, the SOC command unit 15 obtains the target SOC (A2) that is ideal for the storage battery 8 at the present time, taking into account the acquired current SOC (A1) and the current power generation state of the solar battery 6 and the like. This is notified to the storage information acquisition unit 17.

  As shown in FIG. 2, the power storage information acquisition unit 17 acquires the target SOC (A2) from the SOC command unit 15 as information related to the amount of power storage for the storage battery 8, while the current status from the SOC calculation unit 16 of the storage battery 8. The SOC (A1) is obtained. The SOC adjustment current calculation unit 19 is based on the difference information between the current SOC (A1) and the target SOC (A2) received from the storage information acquisition unit 17, or the value of the charging current to be charged to the storage battery 8 or the storage battery The value of the discharge current to be discharged is calculated from

  Here, as shown in FIG. 4, the threshold storage unit 20 stores in advance an SOC adjustment start SOC difference C1 [%] and an SOC adjustment end SOC difference C2 [%]. The SOC adjustment start SOC difference C1 is for determining the timing (SOC adjustment start time D1) for starting the SOC adjustment, and a predetermined difference between the current SOC (A1) and the target SOC (A2). It is specified by the amount. As shown in FIG. 4, when the target SOC (A2) is larger than the current SOC (A1) exceeding the SOC adjustment start SOC difference, charging starts as shown in FIG. On the other hand, when the current SOC (A1) is larger than the target SOC (A2) exceeding the SOC adjustment start SOC difference, the discharge is started. In these cases, the (second) charge / discharge control unit 22 described later sets the SOC adjustment flag (assuming the SOC adjustment flag = 1).

  The SOC adjustment end SOC difference C2 is for determining the timing (SOC adjustment end time D2) for ending the SOC adjustment, and the difference between the current SOC (A1) and the target SOC (A2). Stipulated in As shown in FIG. 4, when the target SOC (A2) is larger than the current SOC (A1) and less than the SOC adjustment end SOC difference, charging ends as shown in FIG. On the other hand, when the current SOC (A1) is larger than the target SOC (A2) and less than the SOC adjustment end SOC difference, the discharge ends. In these cases, the (second) charge / discharge control unit 22 cancels the SOC adjustment flag (sets the SOC adjustment flag = 0).

  Further, as shown in FIG. 6, the threshold storage unit 20 increases the charge current value or the discharge current value at a predetermined rate at the above timing of starting and ending charging or discharging of the storage battery 8. The current increase rate E3 and the current increase rate E4 to be decreased are stored in advance. The current increase rate E3 at the timing of starting charging (and discharging (not shown) shown in FIG. 6 is, for example, 8000 mA / msec, and the current decreasing rate at the timing of finishing charging (and discharging not shown) shown in FIG. E4 is, for example, 8000 mA / msec. With such a configuration, it is possible to obtain an effect of suppressing fluctuations in DC voltage at the time of rising or falling of the charging current or discharging current.

  As shown in FIG. 2, the (second) charge / discharge control unit 22 is configured such that the monitoring voltage of the DC power supply line 9 by the voltage monitoring unit 18 is greater than or equal to the bidirectional chopper discharge start voltage B2 (first reference voltage). Control is performed to charge or discharge the storage battery 8 based on the information on the amount of power stored in the storage battery 8 (calculated by the SOC adjustment current calculation unit 19) when the voltage is equal to or lower than the direction chopper charging start voltage B3 (second reference voltage). Charge / discharge is performed with the adjusted SOC adjustment current). Thus, the subsequent charge / discharge of the storage battery 8 can be efficiently performed by optimizing the SOC. In other words, the home energy management unit 14 (HEMS) predicts the daily power demand in the home and allows for the usage of the storage battery so that the target SOC (A2) is set by a certain time. It becomes possible.

  More specifically, as shown in FIG. 3 to FIG. 6, the (second) charge / discharge control unit 22 performs (SOC adjustment current) based on the difference between the current SOC (A1) and the target SOC (A2). The value of the charging current to the storage battery 8 or the value of the discharge current from the storage battery is adjusted according to the calculation result by the calculation unit 19.

  That is, as shown in FIG. 4, the (second) charge / discharge control unit 22 performs SOC adjustment in which the difference (ΔSOC) between the current SOC (A1) and the target SOC (A2) is the first threshold value. Charging or discharging of the storage battery 8 is started at a timing (SOC adjustment start time D1) exceeding the start SOC difference C1. On the other hand, as shown in FIG. 4, the (second) charge / discharge control unit 22 determines that the difference between the current SOC (A1) and the target SOC (A2) is the SOC adjustment end SOC difference. The charging or discharging of the storage battery is terminated at a timing (SOC adjustment end time D2) that is less than C2 (adjustment end ΔSOC).

  Next, a power supply control method realized by the power supply control system 1 having such a configuration will be described based on the flowchart shown in FIG. 7 in addition to the above-described FIGS. As shown in FIGS. 1 to 3 and 7, first, the voltage monitoring unit 18 of the bidirectional chopper 8 acquires the DC power supply voltage Vdc of the DC power supply line 9 (S [Step] 1). Here, as shown in FIG. 3, when the DC power supply voltage Vdc is less than the bi-directional chopper discharge start voltage B2 or exceeds the bi-directional chopper charge start voltage B3 (NO of B2 ≦ Vdc ≦ B3: S2 NO), the first charge / discharge control unit 21 calculates the charge / discharge current (S3), and charges / discharges the storage battery 8 (S4).

  On the other hand, as shown in FIGS. 3 and 7, when the DC power supply voltage Vdc of the DC power supply line 9 by the voltage monitoring unit 18 is not less than the bidirectional chopper discharge start voltage B2 and not more than the bidirectional chopper charge start voltage B3 (B2 ≦ Vdc ≦ B3 (YES in S2: YES in S2), the (second) charge / discharge control unit 22 performs control to charge or discharge the storage battery 8 based on information on the amount of power stored in the storage battery 8.

  Specifically, as shown in FIGS. 4 and 7, when the difference (ΔSOC) between the current SOC (A1) and the target SOC (A2) exceeds the SOC adjustment start SOC difference C1 (YES in S5). ), The second charge / discharge control unit 22 sets the SOC adjustment flag (SOC adjustment flag = 1: S6). At this time, the SOC adjustment current calculation unit 19 calculates the SOC adjustment current A3, and the storage battery 8 is charged and discharged.

  Thereafter, as shown in FIGS. 4 and 7, when the difference (ΔSOC) between the current SOC (A1) and the target SOC (A2) becomes less than the SOC adjustment end SOC difference C2 (YES in S8). Then, the second charge / discharge control unit 22 releases the SOC adjustment flag (SOC adjustment flag = 0: S9), and temporarily ends the charge / discharge of the storage battery 8.

  As described above, according to the power supply control system 1 according to the present embodiment, as long as the DC power supply voltage Vdc of the DC power supply line 9 does not vary greatly (in the case where the DC power supply voltage Vdc is B2 ≦ Vdc ≦ B3, ) Since the power consumption of the load 12 is covered only by the electric power generated by the interconnection inverter 3 or the solar battery 6, the photovoltaic power generation can be used effectively. That is, by actively increasing the control suspension period of the bidirectional chopper 7, the power supply voltage can be maintained while the power consumption of the bidirectional chopper 7 is reduced. Further, according to the power supply control system 1, the SOC of the storage battery 8 can be optimized after allowing for the usage amount of the storage battery 8.

  The embodiment specifically described above is an exemplification, and the technical scope is not limited thereto, and various modifications can be made without departing from the scope of the invention. For example, instead of the solar cell 6 shown in FIG. 1, for example, a wind power generator that generates DC power can be applied.

  DESCRIPTION OF SYMBOLS 1 ... Feed control system, 2 ... Power system, 3 ... Interconnection inverter, 5 ... PV chopper, 6 ... Solar cell, 7 ... Bidirectional chopper, 8 ... Storage battery, 9 ... DC feed line, 10 ... Feed device, 12 ... Load, 14 ... residential energy management unit, 15 ... SOC command unit, 16 ... SOC calculation unit, 17 ... power storage information acquisition unit, 18 ... voltage monitoring unit, 19 ... SOC adjustment current calculation unit, 20 ... threshold storage unit, 21 ... 1st charging / discharging control part, 22 ... 2nd charging / discharging control part.

Claims (8)

A power supply device that supplies DC power to a load via a power supply line;
A storage battery connected to the power supply line;
A voltage monitoring unit for monitoring the voltage on the power supply line;
When the monitoring voltage by the voltage monitoring unit is less than a first reference voltage, power is discharged from the storage battery onto the power supply line, and the monitoring voltage exceeds a second reference voltage higher than the first reference voltage. In this case, a charge / discharge control unit that charges the storage battery with power from the power supply line,
A power supply control system comprising: A power storage information acquisition unit for acquiring information on the amount of power storage for the storage battery;
A second battery that charges or discharges the storage battery based on the acquired information on the amount of stored electricity when the monitoring voltage by the voltage monitoring unit is not less than the first reference voltage and not more than the second reference voltage. Charge / discharge control unit of
The power supply control system according to claim 1, further comprising: The power storage information acquisition unit acquires a current charge rate and a target charge rate for the storage battery as information on the amount of power storage,
The power supply control system according to claim 1 or 2. The second charging / discharging control unit adjusts a value of a charging current to the storage battery or a value of a discharging current from the storage battery based on a difference between the current charging rate and the target charging rate.
The power supply control system according to claim 2 or 3. The second charge / discharge control unit starts charging or discharging the storage battery at a timing when the difference between the current charging rate and the target charging rate exceeds a first threshold, and the difference is Terminating charging or discharging of the storage battery at a timing that is less than a second threshold;
The power supply control system according to claim 3 or 4. The second charge / discharge control unit raises or lowers the value of the charging current or the value of the discharging current at a predetermined rate at the timing of starting and ending charging or discharging of the storage battery,
The power supply control system according to claim 5. The power supply device includes at least a solar cell,
The power supply control system according to any one of claims 1 to 6. Supplying DC power to a load via a power supply line to which a storage battery is connected;
Monitoring the voltage on the feed line;
When the monitored voltage is less than a first reference voltage, power is discharged from the storage battery onto the feeder line, and the monitored voltage exceeds a second reference voltage that is higher than the first reference voltage. Charging the storage battery with power from the feed line in the case,
A power supply control method.

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