CN115133872A - Optical storage direct current coupling system and detection method thereof - Google Patents

Abstract

The application provides an optical storage direct current coupling system, this system includes m photovoltaic cell group, energy storage battery group, m switches, the control unit, m one-way DC/DC unit and a two-way DC/DC unit, m switches, m photovoltaic cell group with m one-way DC/DC unit one-to-one respectively, the control unit is used for controlling every switch of m switches to switch on or switch off and is used for controlling the square wave duty cycle of the drive signal of two-way DC/DC unit, two-way DC/DC unit still is used for exporting the energy that receives from the energy storage battery group to the switch, the switch that switches on is used for exporting the energy that receives from two-way DC/DC unit to the corresponding photovoltaic cell group. The technical scheme of this application can reduce circuit cost, reduce the loss and to the influence of electric wire netting.

Description

Optical storage direct current coupling system and detection method thereof

Technical Field

The application relates to the technical field of photovoltaic power generation, in particular to a photovoltaic direct current coupling system and a detection method thereof.

Background

Photovoltaic power generation systems include a photovoltaic module, which typically includes a plurality of photovoltaic cell groups. Because the photovoltaic power generation system generates power by converting solar energy into electric energy through the photovoltaic battery pack, the photovoltaic battery pack needs to be detected so as to ensure that the photovoltaic battery pack in the photovoltaic power generation system is in a healthy state.

At present, a method for detecting a photovoltaic battery pack in an operation process of a photovoltaic power generation system comprises the following steps: when the photovoltaic battery pack is detected at night, a direct current-to-alternating current (DC/AC) inverter in a photovoltaic power generation system is awakened; after the DC/AC inverter is subjected to grid-connected operation, the current is reversely poured into the photovoltaic power generation system through the direct current-to-direct current DC/DC reverse pouring circuit; and meanwhile, the photovoltaic battery pack is shot through the camera device, and whether the state of the photovoltaic battery pack is healthy or not is judged based on the shot image.

In this detection method, the DC/AC inverter needs to be waked up, so that the loss is large and the cost is high.

Disclosure of Invention

The application provides an among the light stores up direct current coupled system, has realized waiting to detect the connection of photovoltaic cell group and energy storage battery group through the switch element to in the energy storage battery group to waiting to detect the photovoltaic cell group power supply, and then can detect waiting to detect the photovoltaic cell group. Compared with the existing system, the optical storage direct current coupling system does not need to wake up the DC/AC inverter, so that the circuit cost can be reduced, the loss can be reduced, and the influence on a power grid can be reduced.

In a first aspect, the present application provides a light stores up direct current coupled system, including photovoltaic module, energy storage battery group, switch element and the control unit in the light stores up direct current coupled system, the switch element includes m switches, photovoltaic module includes m photovoltaic cell group, m switches with m photovoltaic cell group one-to-one, m is the positive integer.

Every photovoltaic cell group links to each other with the power output of the switch that corresponds in the m photovoltaic cell group, the power input of every switch in the m switch with the energy storage battery group links to each other, the drive signal input of every switch with the first signal output part of the control unit links to each other.

The control unit is used for sending a first driving signal to a switch unit corresponding to a photovoltaic battery pack to be detected in the m photovoltaic battery packs, and the first driving signal is used for conducting a switch corresponding to the photovoltaic battery pack to be detected.

In the application, a port of each switch for inputting power is called a power input end, a port for outputting power is called a power output end, and a port for inputting a driving signal is called a driving signal input end; the port of the control unit for outputting the drive signal to the switch is referred to as a first signal output.

In this application, specifically, every photovoltaic cell group's positive pole links to each other with the positive pole of the power output of its switch that corresponds, and every photovoltaic cell group's negative pole links to each other with the negative pole of its power output of corresponding switch, and every switch's power input end's positive pole links to each other with the positive pole of energy storage battery group, and every switch's power input end's negative pole links to each other with the negative pole of energy storage battery group.

With reference to the first aspect, in a first possible implementation manner, the optical storage DC-DC coupling system further includes a DC-to-DC/DC unit and a first capacitor, a power input end of each of the m switches is connected to a power output end of the DC/DC unit, a power input end of the DC/DC unit is connected to the energy storage battery pack, an anode of the first capacitor is connected to an anode of the power output end of the DC/DC unit, a cathode of the first capacitor is connected to a cathode of the power output end of the DC/DC unit, and a driving signal input end of the DC/DC unit is connected to a second signal output end of the control unit.

The control unit is further configured to: determining a target square wave duty ratio of a driving signal of the DC/DC unit according to an actual current value of the photovoltaic battery pack to be detected and a target current value set for the photovoltaic battery pack to be detected; and sending a second driving signal to the DC/DC unit, wherein the square wave duty ratio of the second driving signal is the target square wave duty ratio.

In this implementation, a port of the DC/DC unit for receiving power output by the energy storage battery pack is referred to as a power input terminal, a port for outputting power to the photovoltaic battery pack is referred to as a power output terminal, and a port for inputting a driving signal is referred to as a driving signal input terminal.

In this implementation, specifically, the positive electrode of the power input end of each switch is connected to the positive electrode of the power output end of the DC/DC unit, the negative electrode of the power input end of each switch is connected to the negative electrode of the power output end of the DC/DC unit, the negative electrode of the energy storage battery pack is connected to the negative electrode of the power input end of the DC/DC unit, and the positive electrode of the energy storage battery pack is connected to the positive electrode of the power input end of the DC/DC unit.

With reference to the first possible implementation manner, in a second possible implementation manner, the control unit is further configured to: updating the target current value set for the photovoltaic battery pack to be detected to a new target current value under the condition that the brightness of the image shot by the camera equipment for the photovoltaic battery pack to be detected is less than or equal to a preset brightness value; re-detecting the actual current value of the photovoltaic battery pack to be detected; re-determining the target square wave duty ratio of the driving signal of the DC/DC unit according to the re-detected actual current value and the updated target current value of the photovoltaic battery pack to be detected; and sending a third driving signal to the DC/DC unit, wherein the square wave duty ratio of the third driving signal is the re-determined target square wave duty ratio.

With reference to the first or second possible implementation manner, in a third possible implementation manner, optionally, the DC/DC unit may be a bidirectional DC/DC unit. Therefore, the electric energy output by the photovoltaic battery pack can be stored in the energy storage battery pack through the bidirectional DC/DC unit.

With reference to the first, second, or third possible implementation manner, in a fourth possible implementation manner, the first capacitor is a bus capacitor in the optical storage dc coupling system.

With reference to the fourth possible implementation manner, in a fifth possible implementation manner, the system further includes m DC/DC units in one-to-one correspondence with the m photovoltaic cell groups, and each photovoltaic cell group in the m photovoltaic cell groups is connected to the bus capacitor through the corresponding DC/DC unit.

Among them, a port for inputting power in the DC/DC unit is referred to as a power input terminal, and a port for outputting power is referred to as a power output terminal.

Specifically, the positive electrode of each photovoltaic battery pack is connected with the positive electrode of the power input end of the corresponding DC/DC unit, the negative electrode of each photovoltaic battery pack is connected with the negative electrode of the power input end of the corresponding DC/DC unit, the positive electrode of the power output end of each DC/DC unit is connected with the positive electrode of the bus capacitor, and the negative electrode of the power output end of each DC/DC unit is connected with the negative electrode of the bus capacitor.

With reference to the fifth possible implementation manner, in a sixth possible implementation manner, each DC/DC unit of the m DC/DC units is a unidirectional DC/DC unit.

With reference to the fifth possible implementation manner or the sixth possible implementation manner, in a seventh possible implementation manner, the system further includes a DC-to-AC DC/AC unit, an anode of a power input end of the DC/AC unit is connected to an anode of the bus capacitor, a cathode of the power input end of the DC/AC unit is connected to a cathode of the bus capacitor, and a power output end of the DC/AC unit is used for connecting to a power grid.

In a second aspect, the present application provides a control device for testing a photovoltaic cell stack, the device comprising functional modules for implementing the method of the second aspect or any one of its possible implementations, the functional modules being implemented by software and/or hardware modes.

In a third aspect, the present application provides a control apparatus for testing a photovoltaic cell stack, the apparatus comprising a processor coupled with a memory, the processor being configured to execute program code in the memory to implement the method of the first aspect or any one of its possible implementations.

In a fourth aspect, the present application provides a computer-readable storage medium having stored thereon a computer program or instructions which, when executed by a processor, implement the method as in the first aspect or any one of its possible implementations.

In a fifth aspect, the present application provides a computer program product comprising computer program code, which is characterized in that when the computer program code runs on a computer, the computer is caused to implement the method as in the first aspect or any one of the possible implementations thereof.

In a sixth aspect, the present application provides an optical storage DC coupling system, which includes a photovoltaic module, an energy storage battery pack, a switch unit, a control unit, m unidirectional DC/DC units, and a bidirectional DC/DC unit, where the switch unit includes m switches, the photovoltaic module includes m photovoltaic battery packs, the m switches, the m photovoltaic battery packs, and the m unidirectional DC/DC units are respectively in one-to-one correspondence, and m is a positive integer; each of the m unidirectional DC/DC units is to output energy received from a corresponding photovoltaic cell group to the bidirectional DC/DC unit; the bidirectional DC/DC unit is used for outputting the energy received from each unidirectional DC/DC unit to the energy storage battery pack; the control unit is used for controlling each switch of the m switches to be switched on or switched off and controlling the square wave duty ratio of the driving signal of the bidirectional DC/DC unit; the bidirectional DC/DC unit is also used for outputting the energy received from the energy storage battery pack to the switch unit; the switch unit is used for outputting the energy received from the bidirectional DC/DC unit to the corresponding photovoltaic battery pack through the conducted switch.

With reference to the sixth aspect, in a first possible implementation manner, the optical storage dc coupling system further includes a bus capacitor; wherein each unidirectional DC/DC unit is specifically configured to output energy received from a corresponding photovoltaic cell group to the bus capacitance; the bus capacitor is used for outputting the energy received from each unidirectional DC/DC unit to the bidirectional DC/DC unit; the bus capacitance is further used for outputting energy received from each unidirectional DC/DC unit and/or from the bidirectional DC/DC unit to a power grid; the bidirectional DC/DC unit is specifically used for outputting the energy received from the bus capacitor to the energy storage battery pack and outputting the energy received from the energy storage battery pack to the bus capacitor; the bus capacitor is also used for outputting the energy received from the bidirectional DC/DC unit to the switch unit.

With reference to the first possible implementation manner, in a second possible implementation manner, the system further includes a DC-to-AC DC/AC unit; wherein the bus capacitor is specifically configured to: outputting to the DC/AC units the energy received from the each unidirectional DC/DC unit and/or from the bidirectional DC/DC unit; the DC/AC unit is used for outputting the energy received from the bus capacitor to the power grid.

With reference to the sixth aspect or the first or second possible implementation manner, in a third possible implementation manner, the control unit is specifically configured to: determining a target square wave duty ratio of a driving signal of the bidirectional DC/DC unit according to an actual current value of the photovoltaic battery pack corresponding to the conducted switch and a target current value set for the photovoltaic battery pack corresponding to the conducted switch; and sending a driving signal to the bidirectional DC/DC unit, wherein the square wave duty ratio of the driving signal is the target square wave duty ratio.

With reference to the third possible implementation manner, in a fourth possible implementation manner, the control unit is further configured to: updating the target current value set for the photovoltaic battery pack corresponding to the conducted switch to a new target current value under the condition that the brightness of the image shot by the camera equipment for the photovoltaic battery pack corresponding to the conducted switch is smaller than or equal to a preset brightness value; re-detecting the actual current value of the photovoltaic battery pack corresponding to the conducted switch; re-determining the target square wave duty ratio of the driving signal of the bidirectional DC/DC unit according to the re-detected actual current value and the updated target current value of the photovoltaic battery pack corresponding to the conducted switch; and sending new three driving signals to the bidirectional DC/DC unit, wherein the square wave duty ratio of the third driving signal is the re-determined target square wave duty ratio.

Drawings

Fig. 1 is a structural diagram of a photovoltaic dc coupling system in the prior art;

FIG. 2 is a schematic diagram of a photovoltaic DC-coupled system using a prior art EL detection method;

FIG. 3 is a schematic diagram of an optical storage DC coupling system according to an embodiment of the present application;

fig. 4 is a flowchart of an exemplary method for performing EL detection on a photovoltaic cell in an optical storage dc coupling system according to an embodiment of the present application.

Detailed Description

In order to better describe the embodiments of the present application, the related concepts in the embodiments of the present application will be described below.

1. Electro luminescence Effect (EL) detection

EL detection is an image detection method. The principle of using EL detection is as follows: when a photovoltaic battery pack is biased and reverse current is injected, the photovoltaic battery pack can be equivalently regarded as a light-emitting diode with lower luminous efficiency, and can emit light to form an image with certain brightness, namely an EL image; by analyzing the EL image, the problems of hidden cracking, grid breaking, sintering and the like of the photovoltaic battery pack can be found.

Or, it can be said that, for EL detection of a photovoltaic cell set, the following steps can be performed: (1) outputting current or backward flowing current to the photovoltaic battery pack to enable the photovoltaic battery pack to emit images with specific wavelengths; (2) acquiring a photovoltaic battery pack image under a specific wavelength through camera equipment; (3) and judging the faults of the photovoltaic battery pack through an image recognition processing technology.

2. Group string type inverter

An inverter is characterized in that a direct current side can be connected with a plurality of photovoltaic strings which are not connected in parallel, and two-stage power conversion from direct current to direct current and from direct current to alternating current is adopted.

3. Centralized inverter

An inverter is characterized in that a direct current side is connected with a single-circuit or a plurality of photovoltaic strings which are connected in parallel, and direct current to alternating current single-stage power conversion is adopted.

4. Upper computer

The superior communication node of the photovoltaic inverter can adopt various forms such as a data acquisition unit, a network management unit or a power station controller. The functions are as follows: and the data exchange module exchanges data with the control unit and issues instructions to the control unit.

5. Control unit

The main control chip of the photovoltaic inverter may adopt embedded chips such as a Digital Signal Processing (DSP), a Micro Controller Unit (MCU), and the like. The functions are as follows: when the photovoltaic energy storage battery pack works normally in the daytime, the power electronic switches in the direct current/direct current DC/DC unit, the unidirectional DC/DC main circuit and the direct current/alternating current DC/AC main inverter circuit of the inverter are controlled to realize energy conversion among the photovoltaic battery pack, the energy storage battery pack and the alternating current power grid; when EL detection is carried out at night, port voltage, alternating current, bus voltage and reverse irrigation current are sampled, data are interacted with an upper computer, the upper computer receives instructions, a DC/AC main inverter circuit is controlled to adjust the bus voltage and reactive power, a DC/DC unit is controlled to adjust the reverse irrigation current, and a switch switching circuit is controlled to achieve reverse irrigation of the appointed photovoltaic battery pack.

6. DC-to-AC DC/AC main inverter circuit

The inverter circuit part of the photovoltaic inverter can adopt various known circuit topological structures such as two-level, T-type three-level, I-type three-level, five-level, cascade H-bridge multi-level, modular multi-level and the like. The functions are as follows: when the bus works normally in the daytime, the direct current is converted into alternating current, so that energy conversion between the bus capacitor and an alternating current network is realized; after an EL reservation instruction is obtained in the day, after the input energy of the direct current side is lower at night, the grid-connected state is maintained, or after an EL awakening instruction is obtained at night, the direct current on the bus capacitor is quickly inverted into alternating current, and the grid connection is quickly completed; when EL detection is carried out at night, the direct-current side bus voltage is controlled, the continuous adjustable range of the bus voltage is expanded, meanwhile, the grid-connected side reactive power is controlled, and reactive compensation is provided for a power grid.

In the embodiments of the present application, the DC/AC main inverter circuit may also be referred to as a DC/AC unit.

7. DC-to-DC/DC unit

The direct current to direct current power conversion can be realized by adopting a BOOST circuit structure with a boosting function, a BUC circuit structure with a voltage reduction function, or a BUCK-BOOST circuit structure with both boosting and voltage reduction functions.

In the embodiments of the present application, the DC/DC unit may also be referred to as a DC/DC circuit or a DC/DC main circuit.

8. Unidirectional DC/DC main circuit

The DC-DC unidirectional power conversion can be realized by adopting a BOOST circuit structure with a boosting function, a BUC circuit structure with a voltage reduction function or a BUCK-BOOST circuit structure with both boosting and voltage reduction functions. The functions are as follows: when the photovoltaic cell works normally in the daytime, energy transmission from the photovoltaic cell group to the bus capacitor is realized.

In the embodiments of the present application, the unidirectional DC/DC main circuit may also be referred to as a unidirectional DC/DC circuit or a DC/DC unit.

9. Switch unit

A plurality of mechanical switches or power electronic switches may be used to form a switch bank. The functions are as follows: the energy storage battery pack is connected with the DC/DC unit by controlling the combined switch state of the switch, so that night awakening based on electricity taking of the energy storage battery pack can be realized; any one or more groups of photovoltaic battery packs are connected with the DC/DC unit, so that the specified photovoltaic battery packs can be reversely irrigated according to instructions to generate an EL effect.

In the embodiments of the present application, the switching unit may also be referred to as a switching circuit.

10. Bidirectional DC/DC main circuit

The bidirectional power conversion from direct current to direct current can be realized by adopting a BOOST circuit structure with a boosting function, a BUC circuit structure with a voltage reduction function or a BUCK-BOOST circuit structure with both boosting and voltage reduction functions. The functions are as follows: when the photovoltaic energy storage battery pack/energy storage battery works normally in the daytime, energy transmission from the photovoltaic energy storage battery pack/energy storage battery to the bus capacitor is realized, and energy transmission from the bus capacitor to the energy storage battery is realized, namely charging is realized; when EL detection is carried out at night, the battery side voltage of the bidirectional DC/DC circuit is controlled to be DUbus by adjusting the duty ratio D, and therefore the continuous adjustable range of the reverse current is expanded.

In embodiments of the present application, the bidirectional DC/DC main circuit may be referred to as a bidirectional DC/DC unit.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Fig. 1 is an architecture diagram of a photovoltaic dc coupling system in the prior art. As shown in fig. 1, the photovoltaic DC coupling system includes a photovoltaic module, a unidirectional DC/DC main circuit, a bus capacitor, and a DC/AC main inverter circuit, where the photovoltaic module includes m photovoltaic battery packs, and m is a positive integer. Each photovoltaic battery pack is connected with the corresponding unidirectional DC/DC main circuit, the output ends of the m DC/DC circuits are connected in parallel with the DC bus capacitor, and energy transmission from the photovoltaic battery pack to the bus capacitor is realized when the photovoltaic battery pack normally works in the daytime; and the bus capacitor and the DC/AC main inverter circuit are connected in parallel and then connected with a unidirectional/three-phase power grid.

When the system normally works in the daytime, the photovoltaic battery pack absorbs sunlight to convert light energy into electric energy, then the energy is transmitted to the bus capacitor through the unidirectional DC/DC main circuit, and then the energy is transmitted to a single-phase/three-phase power grid through the DC/AC main inverter circuit to realize power generation.

Because the photovoltaic battery pack can convert the energy of solar illumination into electric energy, the health state of the photovoltaic battery pack directly determines how much electric energy can be generated by the photovoltaic power generation system. Once a photovoltaic battery pack fails, the electric energy output by the photovoltaic battery pack can be obviously influenced, and the loss is caused to the power generation amount and the income of a photovoltaic power station. Therefore, the detection of the photovoltaic battery pack is required to ensure that the photovoltaic battery pack in the photovoltaic power generation system is in a healthy state.

At present, a commonly used detection method of a photovoltaic cell pack is an EL detection method. Fig. 2 is a schematic diagram of a photovoltaic dc coupling system using a conventional EL detection method.

As shown in fig. 2, when detecting the photovoltaic cell set at night, the upper computer sends a detection instruction to the control unit and informs the control unit which one of the m groups of photovoltaic cell sets is the photovoltaic cell set to be detected; the control unit sends a control signal to the DC/AC main inverter circuit to wake up the DC/AC main inverter circuit, sends a control signal to the AC/DC auxiliary charging circuit to supply power to the main inverter circuit, and sends a control signal to the switch unit to enable the switch unit to communicate the photovoltaic battery pack to be detected with the DC/DC reverse charging circuit; after the DC/AC inverter is subjected to grid-connected operation, the control unit sends control information to the DC/DC backward flow circuit to control the DC/DC reflection circuit to adjust the value of backward flow current; and shooting an image of the photovoltaic battery pack to be detected with the reverse current input through a camera, and detecting the photovoltaic battery pack according to the image.

The DC/AC main inverter circuit usually does not work at night, and in the existing EL detection method, when the photovoltaic battery pack is subjected to EL detection at night, the DC/AC main inverter circuit needs to be awakened to be connected to the grid for operation, so that energy is obtained from the grid to reversely flow current to the photovoltaic battery pack. Because the working power consumption of the DC/AC inverter is larger, the loss of the existing EL detection method is higher, and further the cost is higher.

Aiming at the technical problems of large loss and high cost of a detection method for a photovoltaic battery pack in the prior art, the embodiment of the application provides a novel technical scheme for detecting the photovoltaic battery pack. In the technical scheme provided by the application, the energy storage battery pack is used for supplying power to the photovoltaic battery pack to be detected through the switch connected with the photovoltaic battery pack to be detected, the DC/AC inverter does not need to be awakened at night for grid-connected work, and loss can be reduced.

Furthermore, in the technical scheme of the application, the magnitude of the electric signal output from the energy storage battery pack to the battery pack to be detected is adjusted through the DC/DC unit and the capacitor, so that the continuous adjustment of the current signal output from the energy storage battery pack to the battery pack to be detected can be realized.

Fig. 3 is a schematic diagram of an optical storage dc coupling system according to an embodiment of the present application. As shown in fig. 3, the optical storage DC coupling system may include an energy storage battery pack, a bidirectional DC/DC unit, m photovoltaic battery packs, m unidirectional DC/DC units, a bus capacitor, a DC/AC unit, a switch unit, an upper computer, and a control unit, where m is a positive integer. The bidirectional DC/DC unit may also be referred to as an energy storing DC/DC unit.

The m photovoltaic cell groups comprise photovoltaic cell groups 1 to m, and the m photovoltaic cell groups can be synthesized into a photovoltaic module; the switch unit comprises m switches from 1 to m; the m unidirectional DC/DC units include unidirectional DC/DC unit 1 to unidirectional DC/DC unit m.

The m photovoltaic battery packs correspond to the m unidirectional DC/DC units and the m switches one by one respectively, wherein the positive pole of the photovoltaic battery pack i, the positive pole of the power output end of the switch i and the positive pole of the power input end of the unidirectional DC/DC unit i are connected, the negative pole of the photovoltaic battery pack i, the negative pole of the power output end of the switch i and the negative pole of the power input end of the unidirectional DC/DC unit i are connected, i takes a value from 1 until i is equal to m, and i is an integer.

The positive pole of the power input end of each switch, the positive pole of the power output end of each unidirectional DC/DC unit, the positive pole of the bus capacitor, the positive pole of one end of the bidirectional DC/DC unit and the positive pole of the power input end of the DC/AC unit are connected, and the negative pole of the power input end of each switch, the negative pole of the power output end of each unidirectional DC/DC unit, the negative pole of the bus capacitor, the negative pole of the one end of the bidirectional DC/DC unit and the negative pole of the power input end of the DC/AC unit are connected.

The negative pole of the other end of the bidirectional DC/DC unit is connected with the negative pole of the energy storage battery pack, the positive pole of the other end of the bidirectional DC/DC unit is connected with the positive pole of the energy storage battery pack, and the power output end of the DC/AC unit is connected with the unidirectional/three-phase power grid.

The driving signal input end of each switch in the m switches is connected with the control unit, the driving signal input end of the bidirectional DC/DC unit is connected with the control unit, and the control unit is connected with the upper computer.

The control unit can store the corresponding relation between the switches and the photovoltaic battery pack, and can send a driving signal to each switch to control the on or off of the switch; the control unit can send drive signal to two-way DC/DC unit to the gain (for example boost gain or step-down gain) of this two-way DC/DC unit of control, and the host computer can send the instruction to the control unit, and the control unit can send the various data of oneself monitoring to the host computer.

The optical storage dc coupling system according to an embodiment of the present application is introduced above, and the working principle of the optical storage dc coupling system is described below.

In the daytime, the photovoltaic battery pack in the light storage direct current coupling system can absorb sunlight, convert light energy into electric energy, supply the electric energy to the bus capacitor through the corresponding unidirectional DC/DC, and supply the energy to a single-phase/three-phase power grid through the DC/AC unit, or the energy output by the bus capacitor can be stored in the energy storage battery pack through the bidirectional DC/DC unit. The voltage output by the bus capacitor is high in general, and the bidirectional DC/DC unit can step down the voltage output by the bus capacitor and then output the voltage to the energy storage battery pack.

When EL detection needs to be performed on the photovoltaic cell set in the optical storage dc coupling system, for example, when EL detection needs to be performed on the photovoltaic cell set at night, a schematic flowchart of an EL detection method according to an embodiment of the present application is shown in fig. 4. The EL detection method may include S401, S402, S403, S404, S405, S406, S407, and S408.

S401, the upper computer sends an EL detection instruction to the control unit.

The EL detection instructions are used to instruct the control unit to detect one or more photovoltaic cell groups in the photovoltaic module. In some implementation modes, the upper computer sends the serial number of the photovoltaic battery pack to be detected after sending the EL detection instruction to the control unit.

S402, the control unit sends a driving signal to a switch corresponding to the battery pack to be detected in the switch unit, and the driving signal is used for conducting the switch.

Specifically, after receiving the EL instruction, the control unit may determine which switch is the switch to be turned on according to the correspondence between the serial number of the photovoltaic cell and the switch, and send a driving signal for turning on the switch to the switch, where the driving signal may also be referred to as a control signal.

The switch corresponding to the photovoltaic battery pack to be detected is conducted, the photovoltaic battery pack to be detected is conducted with the bus capacitor, or the photovoltaic battery pack to be detected is conducted with the bidirectional DC/DC unit, and finally the photovoltaic battery pack to be detected is conducted with the energy storage battery pack to be equivalent, so that electric energy of the energy storage battery pack can be output to the photovoltaic battery pack to be detected, and the photovoltaic battery pack to be detected is made to emit light.

And S403, the control unit sends a driving signal to the bidirectional DC/DC unit, and the driving signal is used for controlling the magnitude of the reverse current value output by the bidirectional DC/DC unit.

For example, a target value of the back-flow current may be stored in the control unit; then, the control unit can determine the square wave duty ratio of the driving signal based on the target value of the reverse flow current so as to control the boost gain of the bidirectional DC/DC unit, and thus, the reverse flow current of the target value output by the energy storage battery pack to the photovoltaic battery pack to be detected can be controlled.

In addition, because the bidirectional DC/DC unit is connected with the bus capacitor in parallel, the magnitude of the reverse current value can be controlled by the voltage of the bus capacitor, so that double-loop control from the bus voltage to the feedback current can be realized, the continuous control of the reverse current can be realized better, and the control range of the reverse current can be expanded better.

S404, the camera shoots the photovoltaic battery pack to be detected, and EL detection is carried out on the photovoltaic battery pack to be detected based on the image obtained by shooting.

S405, the upper computer sends a reverse current flowing instruction to the control unit, and the instruction is used for indicating a new target value of the reverse current flowing.

For example, in the case where it is found that the image is not clear enough, for example, the brightness of the image is not sufficient, and more specifically, the brightness of the image is smaller than the preset brightness threshold value, in the process of performing EL detection based on the captured image, since a larger back-sink current is required to make the image of the photovoltaic cell group to be detected clearer, the upper computer may send a back-sink current instruction for indicating a new target value to the control unit. Typically, the new target value is greater than the target value being used.

S406, the control unit resends the driving signal to the bidirectional DC/DC unit according to the backward current instruction, and then the step S404 is executed again.

After the control unit resends the driving signal to the bidirectional DC/DC unit, reference may be made to S405 for a principle that the energy storage battery pack outputs a reverse current to the photovoltaic battery pack to be detected, which is not described herein again.

It is understood that steps S404 to S406 may be repeatedly performed for each photovoltaic cell group to be detected until clear images satisfying the number requirement are captured.

And S407, the upper computer sends a detection ending instruction to the control unit.

And S408, the control unit outputs a control signal for turning off the switch to the switch corresponding to the photovoltaic battery pack to be detected. That is to say, the control unit turns off the corresponding switch according to the detection ending instruction, and ends the detection of the photovoltaic battery pack to be detected, so as to save the energy consumption of the energy storage battery pack.

It can be understood that the control unit outputs a control signal for turning off the switch to the switch corresponding to the photovoltaic battery pack to be detected, and simultaneously stops sending the driving signal to the bidirectional DC/DC unit, so as to avoid wasting resources of the control unit.

In this embodiment, after a clear image meeting the number requirement is obtained by shooting for one photovoltaic battery pack to be detected, S401 to S408 may be performed again for the next photovoltaic battery pack to be detected.

Compared with the prior art, the technical scheme provided by the application omits an AC/DC auxiliary charging circuit and a DC/DC reverse charging circuit, and utilizes the energy storage DC/DC circuit in the energy storage system to realize energy reverse charging and bus voltage regulation, so that the cost can be reduced.

Moreover, compared with the prior art, the technical scheme of the application adopts the energy storage DC/DC circuit to replace a reverse-injection DC/DC main circuit, so that the EL reverse-injection current adjusting range can be expanded, damage to the assembly is avoided, and the detection precision and reliability are improved.

In addition, because the DC/AC inverter does not need to be connected to the grid in the detection process, the loss and the influence on the power grid can be reduced.

It is to be understood that the system shown in fig. 3 is merely an example, and that other embodiments of the present application may include more or fewer components. For example, the system in one embodiment of the present application may not include a bidirectional DC/DC unit, or the bidirectional DC/DC unit may not be connected in parallel with the bus capacitor, or the first capacitor connected in parallel with the bidirectional DC/DC unit may not be the bus capacitor, or the bidirectional DC/DC unit may be replaced with a unidirectional DC/DC unit, or the like.

Alternatively, the connection manner of the components in the system in the other embodiments of the present application is different from that in the system shown in fig. 3. For example, m unidirectional DC/DC units may be sequentially connected in series, and then the positive electrode of the power input terminal of the first unidirectional DC/DC unit is connected to the positive electrode of the corresponding photovoltaic cell group, the negative electrode of the power input terminal of the first unidirectional DC/DC unit is connected to the negative electrode of the corresponding photovoltaic cell group, the positive electrode of the power output terminal of the last unidirectional DC/DC unit is connected to the positive electrode of the bus capacitor, and the negative electrode of the power output terminal of the last unidirectional DC/DC unit is connected to the negative electrode of the bus capacitor.

It is understood that the method described in fig. 4 is merely an example, and that methods in other embodiments of the present application may include more or fewer steps. For example, the method according to another embodiment of the present application may not include S404 to S406.

It will be appreciated that the above-described embodiments may be implemented, in whole or in part, by software, hardware, firmware, or any other combination. When implemented in software, the above-described embodiments may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. The procedures or functions described in accordance with the embodiments of the present application are produced in whole or in part when the computer instructions or the computer program are loaded or executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, data center, etc., that contains one or more collections of available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. The semiconductor medium may be a solid state disk.

It should be understood that the term "and/or" herein is merely one type of association relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. In addition, the "/" in this document generally indicates that the former and latter associated objects are in an "or" relationship, but may also indicate an "and/or" relationship, which may be understood with particular reference to the former and latter text.

In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple.

It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not imply any order of execution, and the order of execution of the processes should be determined by their functions and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: u disk, removable hard disk, read only memory, random access memory, magnetic or optical disk, etc. for storing program codes.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (14)

1. An optical storage direct current coupling system is characterized by comprising a photovoltaic assembly, an energy storage battery pack, a switch unit, a control unit, m unidirectional direct current to direct current DC/DC units and a bidirectional DC/DC unit, wherein the switch unit comprises m switches, the photovoltaic assembly comprises m photovoltaic battery packs, the m switches, the m photovoltaic battery packs and the m unidirectional DC/DC units are respectively in one-to-one correspondence, and m is a positive integer;

each of the m unidirectional DC/DC units is to output energy received from a corresponding photovoltaic cell group to the bidirectional DC/DC unit;

the bidirectional DC/DC unit is used for outputting the energy received from each unidirectional DC/DC unit to the energy storage battery pack;

the control unit is used for controlling each switch of the m switches to be switched on or switched off and controlling the square wave duty ratio of the driving signal of the bidirectional DC/DC unit;

the bidirectional DC/DC unit is also used for outputting the energy received from the energy storage battery pack to the switch unit;

the switch unit is used for outputting the energy received from the bidirectional DC/DC unit to the corresponding photovoltaic battery pack through the conducted switch.

2. The system of claim 1, wherein the optical storage dc coupling system further comprises a bus capacitor;

wherein each unidirectional DC/DC unit is specifically configured to output energy received from a corresponding photovoltaic cell group to the bus capacitance;

the bus capacitor is used for outputting the energy received from each unidirectional DC/DC unit to the bidirectional DC/DC unit;

the bus capacitance is further used for outputting energy received from each unidirectional DC/DC unit and/or from the bidirectional DC/DC unit to a power grid;

the bidirectional DC/DC unit is specifically used for outputting the energy received from the bus capacitor to the energy storage battery pack and outputting the energy received from the energy storage battery pack to the bus capacitor;

the bus capacitor is also used for outputting the energy received from the bidirectional DC/DC unit to the switch unit.

3. The system of claim 2, further comprising a DC to AC DC/AC unit;

wherein the bus capacitor is specifically configured to: outputting to the DC/AC units the energy received from the each unidirectional DC/DC unit and/or from the bidirectional DC/DC unit;

the DC/AC unit is used for outputting the energy received from the bus capacitor to the power grid.

4. The system according to any one of claims 1 to 3, characterized in that the control unit is specifically configured to:

determining a target square wave duty ratio of a driving signal of the bidirectional DC/DC unit according to an actual current value of the photovoltaic battery pack corresponding to the conducted switch and a target current value set for the photovoltaic battery pack corresponding to the conducted switch;

and sending a driving signal to the bidirectional DC/DC unit, wherein the square wave duty ratio of the driving signal is the target square wave duty ratio.

5. The system of claim 4, wherein the control unit is further configured to:

updating the target current value set for the photovoltaic battery pack corresponding to the conducted switch to a new target current value under the condition that the brightness of the image shot by the camera equipment for the photovoltaic battery pack corresponding to the conducted switch is smaller than or equal to a preset brightness value;

re-detecting the actual current value of the photovoltaic battery pack corresponding to the conducted switch;

re-determining a target square wave duty ratio of a driving signal of the bidirectional DC/DC unit according to the re-detected actual current value and a target current value updated for the photovoltaic battery pack corresponding to the conducted switch;

and sending a third driving signal to the bidirectional DC/DC unit, wherein the square wave duty ratio of the third driving signal is the re-determined target square wave duty ratio.

6. The optical storage direct current coupling system is characterized by comprising a photovoltaic assembly, an energy storage battery pack, a switch unit and a control unit, wherein the switch unit comprises m switches, the photovoltaic assembly comprises m photovoltaic battery packs, the m switches correspond to the m photovoltaic battery packs one by one, and m is a positive integer;

each photovoltaic battery pack in the m photovoltaic battery packs is connected with the power supply output end of the corresponding switch, the power supply input end of each switch in the m switches is connected with the energy storage battery pack, and the driving signal input end of each switch is connected with the first signal output end of the control unit;

the control unit is used for sending a first driving signal to a switch corresponding to a photovoltaic battery pack to be detected in the m photovoltaic battery packs, and the first driving signal is used for conducting the switch corresponding to the photovoltaic battery pack to be detected.

7. The system of claim 6, further comprising a DC-to-DC/DC unit and a first capacitor, wherein a power input of each of the m switches is connected to a power output of the DC/DC unit, a power input of the DC/DC unit is connected to the energy storage battery, an anode of the first capacitor is connected to an anode of the power output of the DC/DC unit, a cathode of the first capacitor is connected to a cathode of the power output of the DC/DC unit, and a driving signal input of the DC/DC unit is connected to the second signal output of the control unit;

the control unit is further configured to:

determining a target square wave duty ratio of a driving signal of the DC/DC unit according to an actual current value of the photovoltaic battery pack to be detected and a target current value set for the photovoltaic battery pack to be detected;

and sending a second driving signal to the DC/DC unit, wherein the square wave duty ratio of the second driving signal is the target square wave duty ratio.

8. The system of claim 7, wherein the control unit is further configured to:

updating the target current value set for the photovoltaic battery pack to be detected to a new target current value under the condition that the brightness of the image shot by the camera equipment for the photovoltaic battery pack to be detected is less than or equal to a preset brightness value;

re-detecting the actual current value of the photovoltaic battery pack to be detected;

re-determining the target square wave duty ratio of the driving signal of the DC/DC unit according to the re-detected actual current value and the updated target current value of the photovoltaic battery pack to be detected;

and sending a third driving signal to the DC/DC unit, wherein the square wave duty ratio of the third driving signal is the re-determined target square wave duty ratio.

9. The system according to claim 7 or 8, wherein the DC/DC unit is a bidirectional DC/DC unit.

10. The system of any one of claims 7 to 8, wherein the first capacitance is a bus capacitance in the optical storage DC coupling system.

11. A method for detecting a photovoltaic battery pack, wherein the method is applied to an optical storage dc coupling system, the optical storage dc coupling system includes a photovoltaic module, an energy storage battery pack, a switch unit and a control unit, the switch unit includes m switches, the photovoltaic module includes m photovoltaic battery packs, the m switches correspond to the m photovoltaic battery packs one to one, m is a positive integer, each of the m photovoltaic battery packs is connected to a power output terminal of a corresponding switch, a power input terminal of each of the m switches is connected to the energy storage battery pack, a driving signal input terminal of each switch is connected to a first signal output terminal of the control unit, and the method is performed by the control unit, and the method includes:

determining a photovoltaic battery pack to be detected in the m photovoltaic battery packs;

and sending a first driving signal to the switch corresponding to the photovoltaic battery pack to be detected, wherein the first driving signal is used for conducting the switch corresponding to the photovoltaic battery pack to be detected.

12. The method according to claim 11, wherein the optical storage DC coupling system further comprises a DC-to-DC/DC unit and a first capacitor, a power input terminal of each of the m switches is connected to a power output terminal of the DC/DC unit, a power input terminal of the DC/DC unit is connected to the energy storage battery, an anode of the first capacitor is connected to an anode of the power output terminal of the DC/DC unit, a cathode of the first capacitor is connected to a cathode of the power output terminal of the DC/DC unit, and a driving signal input terminal of the DC/DC unit is connected to the second signal output terminal of the control unit;

the method further comprises the following steps:

determining a target square wave duty ratio of a driving signal of the DC/DC unit according to an actual current value of the photovoltaic battery pack to be detected and a target current value set for the photovoltaic battery pack to be detected;

and sending a second driving signal to the DC/DC unit, wherein the square wave duty ratio of the second driving signal is the target square wave duty ratio.

13. The method of claim 12, further comprising:

updating the target current value set for the photovoltaic battery pack to be detected to a new target current value under the condition that the brightness of the image shot by the camera equipment for the photovoltaic battery pack to be detected is less than or equal to a preset brightness value;

re-detecting the actual current value of the photovoltaic battery pack to be detected;

re-determining the target square wave duty ratio of the driving signal of the DC/DC unit according to the re-detected actual current value and the updated target current value of the photovoltaic battery pack to be detected;

and sending a third driving signal to the DC/DC unit, wherein the square wave duty ratio of the third driving signal is the re-determined target square wave duty ratio.

14. The method of claim 13, wherein the first capacitor is a bus capacitor in the optical storage dc coupling system.

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