JP2022096820A - Storage battery control device - Google Patents

Abstract

To provide a storage battery control device that can perform maximum power point tracking control without detecting an output current of a solar cell.SOLUTION: A storage battery control device includes a DC/DC converter 52 connected between a common connection point (DC line 40) of a solar cell 30 having a solar panel and a solar power conditioner 32 that operates independently and a storage battery 20, and a DC converter control unit 54 that controls the DC/DC converter 52, and the DC converter control unit 54 changes a DC voltage by ΔV, and MPPT control (mountain climbing method) is performed to follow the maximum power point by repeating the change in a DC voltage Vdc by ΔV of the same code when the storage battery output power Pbat decreases, and by ΔV of the inverted code when the storage battery output power Pbat increases.SELECTED DRAWING: Figure 1

Description

The present invention assists maximum power point tracking control (hereinafter, also referred to as MPPT (Maximum Power Point Tracking) control) during independent operation of a solar power conditioner (hereinafter, also referred to as solar PCS). The present invention relates to a storage battery control device connected in parallel with a solar cell having a solar panel on a DC link.

Conventionally, as a storage battery control device connected to a DC link of a photovoltaic PCS, for example, the device described in Patent Document 1 has been proposed.

FIG. 3 shows the configuration of the power supply system described in Patent Document 1, in which a storage battery control device is connected in parallel to a DC link in order to assist MPPT control of the photovoltaic PCS during interconnection operation with the power system. There is.

The output side of the solar cell 30 having the solar panel is connected to the DC side of the solar PCS 32 via the DC line 40. The AC side of the solar PCS 32 is connected to the load 34 and the power system 36. The storage battery 20 is connected to the DC line 40 via the storage battery control device 10.

The storage battery control device 10 is connected between the DC line 40 and the storage battery 20, and is a DC / DC converter (DC power) that charges the output of the solar battery 30 to the storage battery 20 or discharges the power of the storage battery 20 to the DC line 40. Converter) 12, a current sensor 41 that detects the output current of the solar cell 30, a current sensor 42 that detects the input current of the solar PCS 32, and a voltage sensor 16 that detects the voltage on the DC line 40 side of the DC / DC converter 12. A DC converter control unit 14 that controls the DC / DC converter 12 so that the charge / discharge power of the storage battery 20 becomes a desired value based on each detection signal of the above is provided.

FIG. 3 shows a configuration in which the photovoltaic PCS 32 mainly performs MPPT control during interconnection operation with the power system 36. However, when the photovoltaic PCS 32 is disconnected from the power system 36 and operated independently, FIG. 4 shows. The configuration shown is conceivable.

In FIG. 4, the same parts as those in FIG. 3 are indicated by the same reference numerals, and the power system 36 is excluded.

The DC converter control unit 14 has an output current Ipv of the solar cell 30 detected by the current sensor 41, a DC voltage Vdc on the DC line 40 side of the DC / DC converter 12 detected by a voltage sensor (not shown), and a current sensor 18. The DC / DC converter 12 is driven based on the detected storage battery current Ibat and the storage battery voltage Vbat detected by a voltage sensor (not shown) to control the DC voltage of the DC line 40.

At this time, MPPT control is performed so that the solar output power Ppv = Ipv * Vdc is maximized.

The solar PCS 32 has a DC / AC converter 32a that converts DC power into AC power, an output current Ipv of the solar cell 30 detected by the current sensor 32b, and a DC voltage Vdc of the DC line 40 detected by a voltage sensor (not shown). Based on this, it is equipped with a solar PCS control unit 32c that drives a DC / AC converter 32a and controls an AC voltage.

The storage battery control device 10 changes the DC voltage by ΔV, and changes the DC voltage Vdc by ΔV having the same sign when the photovoltaic output power Ppv increases and ΔV having the inverted sign when the solar output power Ppv decreases. Is repeated to follow the maximum power point, and general MPPT control (mountain climbing method) is executed according to the flowchart of FIG.

In FIG. 5, repeated control is executed with the processes of steps S1 to S5 as one control cycle. First, in step S1, the solar output power Ppv = Vdc * Ipv (output power of the solar cell 30) is detected.

Next, in step S2, the solar output power Ppv_z at the previous control cycle and the solar output power Ppv detected this time are compared. If the comparison result is Ppv ≧ Ppv_z, the process proceeds to step S4 as it is, and if Ppv <Ppv_z, the sign of ΔV is inverted in step S3 and then the process proceeds to step S4.

In step S4, the DC voltage Vdc is changed by ΔV (Vdc = Vdc + ΔV), and then the power value is stored in step S5 (Ppv_z = Ppv).

Japanese Patent No. 6531496

In the storage battery control device 10 of FIG. 4, it is necessary to detect the output current Ipv of the solar cell 30 in order to calculate the solar output power Ppv, and therefore a current sensor (41) is required outside the storage battery control device 10. There was a problem.

The present invention solves the above problems, and an object of the present invention is to provide a storage battery control device capable of performing maximum power point tracking control without detecting the output current of the solar cell.

The storage battery control device according to claim 1 for solving the above problems is
A storage battery equipped with a DC power converter connected between a common connection point of a solar cell having a solar panel and a solar power conditioner that operates independently and a storage battery, and a control unit that controls the DC power converter. It ’s a control device,
The control unit
For each control cycle, the storage battery power detection value Pbat_z when the DC voltage Vdc on the common connection point side of the DC power converter is changed by ΔV during the previous control cycle is compared with the storage battery power detection value Pbat during the current control cycle. When the Pbat is smaller than Pbat_z, the Vdc is changed by ΔV of the same code, and when the Pbat is Pbat_z or more, the Vdc is changed by ΔV of the inverted code to control the maximum power point tracking. Characterized by doing.

According to the present invention, since the maximum power point tracking control is performed using the storage battery power detection value, it is not necessary to detect the output current of the solar cell, the current detection points outside the device are reduced, and the device configuration can be configured. It can be simplified.

The block diagram of the apparatus according to the Embodiment of this invention. The flowchart of MPPT control according to the Embodiment of this invention. The block diagram of the power supply system described in the prior art 1. The block diagram in the case of self-sustaining operation in the power supply system of FIG. Flow chart of conventional MPPT control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In the embodiment of the present invention, the electric power used for the determination of MPPT control by the storage battery control device is changed from the solar output power Ppv to the storage battery output power Pbat. Since it is necessary to control the voltage and current of the storage battery in the storage battery control device, a detection point for the storage battery voltage Vbat and the storage battery current Ibat is prepared inside the device, and it is not necessary to add a detection point to the outside.

FIG. 1 shows an apparatus configuration according to an embodiment, and the same parts as those in FIG. 4 are indicated by the same reference numerals. The difference from FIG. 4 in FIG. 1 is that the storage battery control device 10 eliminates the need for a detection point of the output current Ipv of the solar cell 30 (removes the current sensor 41) and determines MPPT control based on the solar output power Ppv. Instead, a storage battery control device 50 that determines MPPT control based on the storage battery output power Pbat is provided.

The storage battery control device 50 is connected between the DC line 40 and the storage battery 20, and is a DC / DC converter 52 (this) that charges the output of the solar battery 30 to the storage battery 20 or discharges the power of the storage battery 20 to the DC line 40. The DC power converter of the present invention), the DC voltage Vdc on the DC line 40 side of the DC / DC converter 52 detected by the voltage sensor (not shown), the storage battery current Ibat detected by the current sensor 58, and the voltage sensor (not shown). A DC converter control unit 54 (control unit of the present invention) that drives a DC / DC converter 52 based on the storage battery voltage Vbat and controls the DC voltage of the DC line 40 is provided.

The storage battery control device 50 changes the DC voltage by ΔV, and changes the DC voltage Vdc by ΔV having the same sign when the storage battery output power Pbat decreases and by ΔV having the inverted sign when the DC voltage increases. The MPPT control (mountain climbing method) peculiar to the present invention for repeatedly following the maximum power point is executed according to the flowchart of FIG.

In FIG. 2, the repetitive control is executed with the processes of steps S11 to S15 as one control cycle. First, in step S11, the storage battery output power Pbat = Vbat * Ibat is detected.

Next, in step S12, the storage battery output power Pbat_z at the previous control cycle and the storage battery output power Pbat detected this time are compared. If the comparison result is Pbat <Pbat_z, the process proceeds to step S14 as it is, and if Pbat ≧ Pbat_z, the sign of ΔV is inverted in step S13 and then the process proceeds to step S14.

In step S14, the DC voltage Vdc is changed by ΔV (Vdc = Vdc + ΔV), and then the power value is stored in step S15 (Pbat_z = Pbat).

By repeatedly executing the process of FIG. 2, MPPT control is performed so that the storage battery output power Pbat = Vbat * Ibat is minimized, and as a result, the maximum power point can be followed.

When the load 34 of the self-sustaining operation and the amount of solar radiation to the solar panel of the solar cell 30 are stable, the maximum power point can be followed by the above MPPT control. When the load fluctuation of the self-sustaining operation or the solar radiation fluctuation to the solar panel occurs, the DC voltage moves to the point temporarily deviated from the maximum power point, but the above fluctuation is performed by continuously performing the above MPPT control. Can follow the maximum power point again after it stabilizes.

As described above, since MPPT control can be performed by the output power of the storage battery, the output current detection points of the solar cell can be reduced and the device configuration can be simplified.

20 ... Storage battery 30 ... Solar battery 32 ... Solar power conditioner 34 ... Load 36 ... Power system 40 ... DC line 50 ... Storage battery control device 52 ... DC / DC converter 54 ... DC converter control unit 58 ... Current sensor

Claims (1)

A storage battery equipped with a DC power converter connected between a common connection point of a solar cell having a solar panel and a solar power conditioner that operates independently and a storage battery, and a control unit that controls the DC power converter. It ’s a control device,
The control unit
For each control cycle, the storage battery power detection value Pbat_z when the DC voltage Vdc on the common connection point side of the DC power converter is changed by ΔV during the previous control cycle is compared with the storage battery power detection value Pbat during the current control cycle. When the Pbat is smaller than Pbat_z, the Vdc is changed by ΔV of the same code, and when the Pbat is Pbat_z or more, the Vdc is changed by ΔV of the inverted code to control the maximum power point tracking. A storage battery control device characterized by doing.

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