KR20140042092A - Solar energy storage device and operation method thereof - Google Patents

Abstract

The present invention relates to a solar energy storage device and an operation method thereof. A control unit detects a power generation situation of a solar cell and a system situation of a system load and outputs a mode control command according to the detected result. A switch unit switches a connection contact point between an energy storage unit and a power conversion device unit according to the mode control command outputted from the control unit. The solar energy storage device and the operation method thereof minimize the loss of power transmitted from the energy storage unit to the system load by switching the connection contact point between the energy storage unit and the power conversion device unit according to the mode control command outputted from the control unit and transmitting the power stored in the energy storage unit to the system load without passing an insulated DC/DC converter. [Reference numerals] (201) Lifting pressure DC/DC converter; (203) Insulated DC/DC converter; (205) DC/AC inverter; (401) Bi-directional DC/DC converter; (500) Control unit; (501) Abnormal situation detection unit; (511) First switch unit; (512) Second switch unit

Description

SOLAR ENERGY STORAGE DEVICE AND OPERATION METHOD THEREOF}

The present invention relates to a solar energy storage device and a method of operating the same, and more particularly, the solar light which can change the connection contact between the power converter unit and the energy storage unit in accordance with the charge / discharge mode control command output from the control unit. An energy storage device and a method of operating the same.

In general, photovoltaic power generation is a system that obtains electricity from the light energy of the sun by using a solar cell that converts sunlight directly into electricity.

Photovoltaic power generation consists of solar cells, storage batteries and power converters. When sunlight shines on a solar cell that combines a P-type semiconductor and an N-type semiconductor, holes and electrons are generated in the solar cell by the energy of the sunlight. At this time, the holes are collected toward the p-type semiconductor and the electrons are collected toward the n-type semiconductor, so that a current flows when a potential difference occurs. The advantage of photovoltaic power generation is that there is no pollution, it can be developed only where it is needed, and it is easy to maintain. On the other hand, there is a disadvantage that the amount of electric power depends on the amount of sunshine, the installation site is limited, the initial investment cost and the power generation cost are high.

Korean Patent Laid-Open No. 10-2011-0123130 relates to a solar cell PCS integrated bidirectional battery charging and discharging device and method, comprising: a first converting a PV voltage from a solar cell into a predetermined DC voltage according to a first DC / DC control; DC / DC converters; A DC / AC inverter connected to the grid to perform grid voltage / DC voltage conversion or DC voltage / grid voltage conversion according to the second DC / DC control; A DC link commonly connected to an output terminal from the first DC / DC converter and an output terminal of the DC / AC inverter to stabilize a DC voltage from the first DC / DC converter and a DC voltage from the DC / AC inverter part; A second DC / DC converter connected between the DC link unit and a battery to convert voltage in both directions according to a second DC / DC control; A voltage / current detector for detecting the PV voltage / current of the solar cell, the battery voltage / current of the battery, the system voltage / current of the system, and the DC link voltage of the DC link unit; And determine one control mode among a plurality of preset control modes based on the voltage and current detected by the voltage / current detector, and determine the first DC / DC converter and the second DC / DC converter according to the determined control mode. And a plurality of solar cells formed on a charge control substrate for controlling a DC / AC inverter, and a plurality of power converters connected to the solar cells individually to convert output from the solar cells. It is characterized by. According to the disclosed technology, it is possible to use solar power, which is basically a clean energy source, deliver power to the grid with PV PCS function, perform the function of battery charger simultaneously, and also If not, it has the effect of delivering battery power to the grid.

However, the thin film module type solar cell uses a solar power converter that is insulated between the input and the output due to the risk of leakage current and electric shock. In this case, since the energy storage unit and the power converter unit are connected to each other to fix the contact points. When discharging the power charged in the battery to the system load it had to go through the isolated DC / DC converter stage in the power converter unit, which caused a problem of power loss.

Korean Patent Publication No. 10-2011-0123130

According to an embodiment of the present invention, it is possible to change the contact point between the power converter and the energy storage device according to the charge / discharge mode control command outputted from the controller, so that the battery does not go through the isolated DC / DC converter in the power converter. An object of the present invention is to provide a solar energy storage device capable of discharging power stored therein and a method of operating the same.

Among the embodiments, the solar energy storage device includes a control unit for sensing the power generation status of the solar cell and the grid status of the grid load and outputs a mode control command according to the detection result; According to the mode control command output from the control unit, the switch unit for changing the contact between the energy storage unit and the power converter unit.

In one embodiment, the control unit may further include an abnormal situation detecting unit for detecting the power generation status of the solar cell and the system status of the system load.

In an embodiment, the controller may generate a charge mode control command or a discharge mode control command according to a result detected by the abnormal situation detection unit and output the generated charge mode control command to the switch unit.

In one embodiment, the switch unit comprises: a first switch unit formed between a capacitor in the power converter unit and a bidirectional DC / DC converter in the energy storage unit; And a second switch unit formed between the bidirectional DC / DC converter and the second capacitor in the power converter unit.

In an embodiment, when the first switch unit receives a charge mode control command output from the controller, the first switch unit connects the first capacitor and the bidirectional DC / DC converter to a battery connected to the bidirectional DC / DC converter. It may be characterized in that to charge the power.

In one embodiment, when receiving the discharge mode control command output from the control unit, the second switch unit connects the bidirectional DC / DC converter and the second capacitor to discharge the power stored in the battery. You can do

Among the embodiments, the operation method of the solar energy storage device includes the steps of sensing the power generation status of the solar cell and the grid status of the grid load; Generating a mode control command according to the detected result; And changing a connection contact between the power converter and the energy storage unit according to the generated mode control command according to the generated mode control command.

In an embodiment, the generating of the mode control command may include generating a charging mode control command when no abnormality occurs in the power generation situation of the solar cell and the system situation of the system load; And generating a discharge mode control command when an abnormal situation occurs in a power generation situation of the solar cell and a system load of the system load.

In an embodiment, the step of changing the connection contact may include connecting the first capacitor in the power converter and the bidirectional DC / DC converter in the energy storage unit when the charging mode control command is input. Charging power to a battery connected to the DC / DC converter; And discharging the power stored in the battery by connecting the bidirectional DC / DC converter and the second capacitor when the discharge mode control command is input.

A solar energy storage device and a method of operating the same according to an embodiment of the present invention store an electric current generated by a solar cell in a battery in an energy storage unit and then store an energy when an abnormal situation occurs to discharge the stored current. By changing the connection point between the power converter and the power converter unit, it is possible to discharge without going through the isolated DC / DC converter in the power converter, thereby minimizing the loss of power transferred from the energy storage unit to the system load. There is this.

1 is a block diagram illustrating a solar energy storage device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a first switch unit and a second switch unit in FIG. 1.
3 is a flowchart illustrating a method of operating a solar energy storage device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

FIG. 1 is a diagram illustrating a solar energy storage device according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram illustrating a first switch unit and a second switch unit in FIG. 1.

1 and 2, the solar energy storage device includes a solar cell 100, a power converter 200, an energy storage unit 400, a control unit 500, and a switch unit 510.

The solar cell 100 may use a second generation thin film module type solar cell which is more efficient than the existing first generation silicon crystalline solar cell. Here, the second-generation thin-film module type solar cell has a risk of leakage current and electric shock, so it is necessary to use an insulated solar power converter.

And second-generation thin-film module solar cell is widely used because of its low cost unlike the first-generation silicon crystalline solar cell made of thick polysilicon wafer, and it can be a solar cell made of glass or stainless steel as the core of future solar power generation. have.

The power converter 200 serves to convert the power generated by the solar cell 100 to the power of the form required by the system load 300, step-up DC / DC converter 201, One capacitor 202, an isolated DC / DC converter 203, a second capacitor 204, and a DC / AC inverter 205 may be configured.

The step-up / down DC / DC converter 201 converts a wide range of voltages of the solar cell module into a constant DC voltage (DC voltage), and charges the converted DC power in the first capacitor 202. Can be.

The first capacitor 202 is formed between the step-down DC / DC converter 201 and the isolated DC / DC converter 203. The DC power output through the step-up / down DC / DC converter 201 may be temporarily stored, and then the stored DC power may be output to the isolated DC / DC converter or output to the first switch unit 511.

The isolated DC / DC converter 203 may be configured using a high frequency transformer, and may electrically insulate between the first capacitor 202 and the second capacitor 204, and the first capacitor 202. After the leakage current is prevented with respect to the DC power output through the) can be output to the second capacitor 204. In addition, the isolated DC / DC converter 203 may be operated by high speed switching pulse width modulation (PWM) driving. Types of the isolated DC / DC converter 203 include full-bridge converters, half-bridge converters, and push-pull converters.

The second capacitor 204 is formed between the isolated DC / DC converter 203 and the DC / AC inverter 205, and briefly receives power input through the isolated DC / DC converter and the second switch unit 512. After storing, the DC power may be output to the DC / AC inverter 205.

The DC / AC inverter 205 is formed between the second capacitor 204 and the grid load 300 and converts DC power into AC power required by the grid load 300 to supply the grid load 300 to the grid load 300. Do it.

The energy storage unit 400 may store power generated from the solar cell 100, or discharge the stored power to the grid load 300, and to the bidirectional DC / DC converter 401 and the battery 402. Can be configured.

The bidirectional DC / DC converter 401 may charge the battery 500 with the power input through the first switch unit 511 or output the power charged with the battery 500 to the second switch unit 512. Can play a role.

The bidirectional DC / DC converter 401 may be a non-isolated buck / boost converter capable of bidirectional power flow, an isolated full-bridge converter, an isolated dual active bridge (DAB) converter, and particularly, a bidirectional buck / In the case of a boost converter, synchronous rectification (Synchronous Rectifier) switching can make the two switches complementary to each other.

The battery 402 stores the power input through the bidirectional DC / DC converter 401, and when the solar cell 100 does not produce power or generates a larger amount of power than the power generated from the solar cell 100. When power is required at the system load 300, the power stored in the battery 402 is discharged to the system load 300 through the bidirectional DC / DC converter 401, thereby enabling stable power supply.

The controller 500 may output a control command to the power converter 200, the first switch unit 511, the second switch unit 512, and the energy storage unit 400. The system status of the system load can be detected and a mode control command can be output according to the detection result. In addition, the controller 500 may include an abnormal situation detection unit 501.

The abnormal situation detecting unit 501 may be formed inside the control unit 500, and may serve to detect a power generation state of the solar cell and a system state of the system load, and the control unit 500 may charge according to the detection result. Generates a mode control command or a discharge mode control command.

The switch unit 510 includes a first switch unit 511 and a second switch unit 512, and according to a mode control command output from the controller 500, the bidirectional DC / DC converter 401 and the power converter. It may serve to change the connection contact between the unit 200.

The first switch unit 511 is formed between the first capacitor 202 and the bidirectional DC / DC converter 401 in the power converter 200, and receives a charge mode control command from the controller 500. In accordance with the charging mode control command, the first capacitor 202 and the bidirectional DC / DC converter 401 in the energy storage unit 400 are connected through a connection contact to output power output from the first capacitor 202. It may serve to output to the bidirectional DC / DC converter 401.

In this case, the connection contact may be configured as a relay or a contact switch.

For example, the relay is formed in a structure in which the iron core becomes an electromagnet when a current flows through the coil core. At this time, the opening and closing of the circuit is performed according to the state of the iron core, and when the current flows in the coil corresponding to the first capacitor 202, the switching bar in the first switch unit 511 is attached to the coil, so that the first switch unit When the current flows through the coil corresponding to the second capacitor 204, the switching bar in the second switch unit 512 attaches to the coil, thereby operating the second switch unit 512. have.

The second switch unit 512 is formed between the bidirectional DC / DC converter 401 and the second capacitor 204 in the power converter 200, and receives a discharge mode control command from the control unit 500. The bidirectional DC / DC converter 401 in the energy storage unit 400 and the second capacitor 204 in the power converter 200 are connected to each other through a connection contact to bidirectionally store the power stored in the battery 402. It may serve to output to the second capacitor 204 through the DC / DC converter 401.

3 is a flowchart illustrating a method of operating a solar energy storage device according to an embodiment of the present invention.

Referring to FIG. 3, first, an abnormal situation detecting unit 501 in the control unit 500 detects a power generation state of a solar cell and a system state of the system load (S301), and the control unit 500 determines a corresponding detection result. It is made (S302).

If the abnormal situation does not occur in step S302 described above, the control unit 500 generates a charging mode control command (S303).

The control unit 500 outputs the generated charge mode control command to the first switch unit 511 (S304), and the first switch unit 511 stores energy with the first capacitor 202 according to the corresponding charge mode control command. The bidirectional DC / DC converter 401 in the unit 400 is connected to each other through a connection contact (S305).

Through the first capacitor 202 and the bidirectional DC / DC converter 401 connected by the first switch unit 511, the power generated by the solar cell 100 is increased by the step-down DC / DC converter 201 and the first. Charging starts with the battery 402 through the capacitor 202, the first switch unit 511, and the bidirectional DC / DC converter 401 (S306).

On the other hand, when an abnormal situation occurs in step S302 described above, the control unit 500 generates a discharge mode control command (S307).

The control unit 500 outputs the generated discharge mode control command to the second switch unit 512 (S308), and the second switch unit 512 is located in the energy storage unit 400 according to the discharge mode control command. The bidirectional DC / DC converter 401 and the second capacitor 204 are connected to each other through a connection contact (S309).

Through the bidirectional DC / DC converter 401 and the second capacitor 204 connected by the second switch unit 512, the power stored in the battery 402 is transferred to the bidirectional DC / DC converter 401 and the second switch unit ( The discharge starts to the grid load 300 via 512, the second capacitor 204 and the DC / AC inverter 205 (310).

Hereinafter, the four operating modes in the operating method of the solar energy storage device according to an embodiment of the present invention.

There are four operating modes in the operation method of the solar energy storage device.

The first operation mode is a case where the power generated from the solar cell 100 is output to the system load 300 while charging the battery 402. The first operation mode corresponds to a case in which the output of the solar cell 100 is sufficient, an abnormal state does not occur, and the state of charge (SOC) of the battery 402 is not in a buffer state. In this case, the first switch unit ( 511 connects the first capacitor 202 and the bidirectional DC / DC converter 401 in the energy storage unit 400 to each other and outputs the power generated by the solar cell 100 to the grid load 300 and at the same time the battery. 402 is also charged.

 The second operation mode is a case where all the power generated from the solar cell 100 is output to the grid load 300. The second operation mode corresponds to the case where the solar cell 100 generates power but the battery 402 is fully charged.

The third operation mode corresponds to a case in which the solar cell 100 generates power, but the power required by the grid load 300 is greater than the power generated from the solar cell 100, in which case the second switch unit ( 512 connects the bidirectional DC / DC converter 401 and the second capacitor 204 to each other and outputs both the power generated in the solar cell 100 and the power stored in the battery 500 to the grid load 300.

The fourth operation mode corresponds to a case in which the solar cell 100 does not produce power, but needs power at the grid load 300 (for example, power failure, photovoltaic power generation, and night sunset). The second switch unit 512 connects the bidirectional DC / DC converter 401 and the second capacitor 204 to each other by a connection contact point, and outputs the power stored in the battery 402 to the grid load 300.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

100: Solar cell
200: power converter 201: step-up DC / DC converter
202: first capacitor 203: isolated DC / DC converter
204: second capacitor 205: DC / AC inverter
300: System load
400: energy storage unit 401: bidirectional DC / DC converter
402: battery
500: control unit 501: abnormal situation detection unit
510: switch unit 511: first switch unit
512: second switch unit

Claims (9)

In the solar energy storage device comprising a power converter for converting the power generated by the solar cell to the power required by the system load and an energy storage unit for storing the power generated by the solar cell,
A control unit that detects a power generation state of the solar cell and a system state of the system load and outputs a mode control command according to a corresponding detection result; And
A switch unit for changing a connection contact between the energy storage unit and the power converter unit according to a mode control command output from the control unit;
Solar energy storage device comprising a.
The apparatus of claim 1, wherein the control unit
An abnormal situation detection unit for detecting a power generation state of the solar cell and a system state of the system load;
Photovoltaic energy storage device further comprising.
The method of claim 2, wherein the control unit
And generating a charge mode control command or a discharge mode control command according to a result detected by the abnormal situation detection unit and outputting the generated charge mode control command or the discharge mode control command to the switch unit.
The method of claim 2, wherein the switch unit
A first switch unit formed between the first capacitor in the power converter unit and the bidirectional DC / DC converter in the energy storage unit; And
A second switch unit formed between the bidirectional DC / DC converter and a second capacitor in the power converter unit;
Solar energy storage device, characterized in that consisting of.
The method of claim 4, wherein the first switch unit
When receiving the charge mode control command output from the control unit, by connecting the first capacitor and the bidirectional DC / DC converter to charge the power to the battery connected to the bidirectional DC / DC converter, characterized in that Solar energy storage.
The method of claim 4, wherein the second switch unit
When receiving the discharge mode control command output from the control unit, the solar energy storage device characterized in that for connecting the bidirectional DC / DC converter and the second capacitor to discharge the power stored in the battery.
In the operating method of the solar energy storage device including a power converter for converting the power generated by the solar cell to the power required by the load and an energy storage unit for storing the power generated by the solar cell,
Detecting a power generation status of the solar cell and a system status of the system load;
Generating a mode control command according to the detected result; And
Changing a connection contact point between the power converter and the energy storage unit according to the generated mode control command;
Operation method of a solar energy storage device comprising a.
The method of claim 7, wherein generating the mode control command
Generating a charging mode control command when an abnormal situation does not occur in a power generation situation of the solar cell and a system load of the system load; And
Generating a discharge mode control command when an abnormal situation occurs in a power generation situation of the solar cell and a system load of the system load;
Operating method of a solar energy storage device comprising a.
The method of claim 8, wherein the step of changing the connection contact
When receiving the charging mode control command, the first capacitor in the power converter unit and the bidirectional DC / DC converter in the energy storage unit are connected to charge the battery connected to the bidirectional DC / DC converter. Letting it do; And
Discharging the power stored in the battery by connecting the bidirectional DC / DC converter and the second capacitor when the discharge mode control command is input;
Operating method of a solar energy storage device comprising a.

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