CN114779871A - Maximum power point tracking method, photovoltaic controller and photovoltaic system - Google Patents

Abstract

The application is applicable to the technical field of photovoltaic power generation, and provides a maximum power point tracking method, a photovoltaic controller and a photovoltaic system, wherein the method comprises the following steps: calculating first output power at the current sampling moment according to the first output voltage and the first output current at the current sampling moment; acquiring a second output voltage and a second output power at the last sampling moment, and calculating a voltage difference between the first output voltage and the second output voltage and a power difference between the first output power and the second output power; determining the disturbance direction of the reference voltage of the maximum power point according to the ratio of the power difference to the voltage difference; determining a target disturbance step length according to the absolute value of the power difference; and updating the reference voltage of the maximum power point of the photovoltaic module according to the disturbance direction and the target disturbance step length so that the photovoltaic module operates according to the updated reference voltage. The embodiment of the application provides a variable-step conductance incremental method for tracking the maximum power point of a photovoltaic module, and the tracking effect of the maximum power point is improved.

Description

Maximum power point tracking method, photovoltaic controller and photovoltaic system

technical field

The application belongs to the technical field of photovoltaic power generation, and in particular relates to a maximum power point tracking method, a photovoltaic controller and a photovoltaic system.

Background technique

In the field of photovoltaic power generation technology, in order to improve the photovoltaic power generation utilization rate of photovoltaic modules, it is necessary to maximize the output power. However, the P-U characteristics of photovoltaic modules are nonlinear and change with the change of the external environment, so it is difficult to control. However, there is always a point of maximum power at a particular temperature or insolation intensity. Therefore, it is necessary to use the MPPT (Maximum Power Point Tracking, maximum power point tracking) algorithm to track the MPP (Maximum Power Point, maximum power point) of the photovoltaic module, and make the photovoltaic module always work at the maximum power point to achieve the maximum power output, improve Photovoltaic power generation utilization.

At present, the commonly used MPPT algorithm is the conductance increment method. The conventional conductance increment method is usually the conductance increment method with a fixed step size, that is, a fixed disturbance step size step is preset, and the maximum power point tracking needs to be performed according to the fixed step size. The disturbance step size step updates the reference voltage Uref of the maximum power point of the photovoltaic module, so that the photovoltaic module works at the maximum power point.

However, there is a problem in the choice of the perturbation step size in the conductance increment method with a fixed step size, which affects the tracking effect of the maximum power point. For example, if the selected disturbance step size is too small, the tracking time of the maximum power point may be too long, which affects the stability of the photovoltaic system. If the selected disturbance step size is too large, although the tracking time of the maximum power point will be shortened, it may cause the deviation of the photovoltaic system to be too large when the PV system is stable, that is, the deviation between the tracked maximum power point and the actual maximum power point is large. , affecting the utilization rate of photovoltaic power generation.

SUMMARY OF THE INVENTION

The embodiments of the present application provide a maximum power point tracking method, a photovoltaic controller, and a photovoltaic system, which can solve the problem of selecting a disturbance step size in the conventional constant-step conductance increment method, which affects the tracking effect of the maximum power point. question.

In a first aspect, an embodiment of the present application provides a maximum power point tracking method, including:

sampling the output voltage and output current of the photovoltaic module to obtain the first output voltage and the first output current at the current sampling time;

Calculate the first output power at the current sampling moment according to the first output voltage and the first output current;

Obtain the second output voltage and the second output power at the last sampling time, calculate the voltage difference between the first output voltage and the second output voltage, and the power of the first output power and the second output power Difference;

determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference;

Determine the target disturbance step size according to the absolute value of the power difference;

According to the disturbance direction and the target disturbance step size, the reference voltage of the maximum power point of the photovoltaic module is updated, so that the photovoltaic module operates according to the updated reference voltage.

In a second aspect, a maximum power point tracking device is provided, including:

The sampling module is used for sampling the output voltage and output current of the photovoltaic module to obtain the first output voltage and the first output current at the current sampling time;

a first processing module, configured to calculate the first output power at the current sampling moment according to the first output voltage and the first output current;

The second processing module is configured to acquire the second output voltage and the second output power at the last sampling time, calculate the voltage difference between the first output voltage and the second output voltage, and calculate the difference between the first output voltage and the second output voltage. the power difference of the second output power;

a first determination module, configured to determine the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference;

a second determining module, configured to determine a target disturbance step size according to the absolute value of the power difference;

An update module, configured to update the reference voltage of the maximum power point of the photovoltaic assembly according to the disturbance direction and the target disturbance step size, so that the photovoltaic assembly operates according to the updated reference voltage.

In a third aspect, a photovoltaic controller is provided, the photovoltaic controller includes a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor The method of the first aspect above is implemented when the computer program is executed.

In a fourth aspect, a photovoltaic system is provided, the photovoltaic system includes a photovoltaic component, a tracking device, a DC bus, and a load, the photovoltaic component is connected to one end of the tracking device, and the other end of the tracking device is connected to the One end of the DC bus is connected to the load, and the other end of the DC bus is connected to the load. The tracking device includes a photovoltaic controller, and the photovoltaic controller is used to implement the method described in the first aspect.

In a fifth aspect, a computer-readable storage medium is provided, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method described in the first aspect is implemented.

In a sixth aspect, an embodiment of the present application provides a computer program product, which, when the computer program product runs on a terminal device, enables the terminal device to execute the method described in any one of the above-mentioned first aspects.

The beneficial effects that the embodiments of the present application have compared with the prior art are:

In this embodiment of the present application, the output voltage and output current of the photovoltaic module can be sampled to obtain the first output voltage and the first output current, and the first output power at the current sampling time can be calculated according to the first output voltage and the first output current, and Obtain the second output voltage and the second output power at the last sampling time, and calculate the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power. Then, according to the ratio of the power difference to the voltage difference, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module is determined, and the target disturbance step size is determined according to the absolute value of the power difference. According to the disturbance direction and the target disturbance step size, the reference voltage of the maximum power point of the photovoltaic module is updated, so that the photovoltaic module operates according to the updated reference voltage. In the embodiment of the present application, by determining the target disturbance step size according to the absolute value of the power difference, a conductance increment method with variable step size is provided to track the maximum power point of the photovoltaic module, which can improve the tracking effect of the maximum power point.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only for the present application. In some embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application;

2 is a schematic diagram of a photovoltaic controller provided by an embodiment of the present application;

3 is a schematic diagram of a P-U characteristic curve of a photovoltaic module provided by an embodiment of the present application;

Fig. 4 is the maximum power point tracking flow chart of a conventional conductance increment method provided by the related art;

5 is a flowchart of a maximum power point tracking method provided by an embodiment of the present application;

6 is a logical schematic diagram of a maximum power point tracking method provided by an embodiment of the present application;

FIG. 7 is a schematic diagram of a P-U characteristic curve of another photovoltaic module provided in an embodiment of the present application;

8 is a flowchart of another maximum power point tracking method provided by an embodiment of the present application;

9 is a logical schematic diagram of a maximum power point tracking method provided by an embodiment of the present application;

10 is a flowchart of a charging control method provided by an embodiment of the present application;

11 is a block diagram of a maximum power point tracking device provided by an embodiment of the present application;

FIG. 12 is a schematic structural diagram of a computer device provided by an embodiment of the present application.

Detailed ways

In the following description, for the purpose of illustration rather than limitation, specific details such as a specific system structure and technology are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It is to be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described feature, integer, step, operation, element and/or component, but does not exclude one or more other The presence or addition of features, integers, steps, operations, elements, components and/or sets thereof.

It will also be understood that, as used in this specification and the appended claims, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

As used in the specification of this application and the appended claims, the term "if" may be contextually interpreted as "when" or "once" or "in response to determining" or "in response to detecting ". Similarly, the phrases "if it is determined" or "if the [described condition or event] is detected" may be interpreted, depending on the context, to mean "once it is determined" or "in response to the determination" or "once the [described condition or event] is detected. ]" or "in response to detection of the [described condition or event]".

In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the description, and should not be construed as indicating or implying relative importance.

References in this specification to "one embodiment" or "some embodiments" and the like mean that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean "one or more but not all embodiments" unless specifically emphasized otherwise. The terms "including", "including", "having" and their variants mean "including but not limited to" unless specifically emphasized otherwise.

For ease of understanding, the implementation environment involved in the embodiments of the present application is first introduced.

FIG. 1 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application. As shown in FIG. 1 , the system includes a photovoltaic module 10 , a tracking device 20 , a DC bus 30 and a load 40 .

The photovoltaic module 10 is connected to one end of the tracking device 20 , the other end of the tracking device 20 is connected to one end of the DC bus 30 , and the other end of the DC bus 30 is connected to the load 40 .

The photovoltaic assembly 10 is used for converting solar energy into electrical energy, and the photovoltaic assembly 10 may be a photovoltaic array or the like. The tracking device 20 is used to perform maximum power point tracking on the output power of the photovoltaic module 10 , so that the photovoltaic module 10 can transmit energy to the DC bus 30 to the maximum extent through the tracking device 20 . The load 40 is connected to the DC bus 30 to obtain the energy output by the photovoltaic module 10 through the tracking device 20 .

The tracking device 20 may include a photovoltaic controller for performing maximum power point tracking on the output power of the photovoltaic assembly 10 . The photovoltaic controller can include a timer, an A/D (Analog/Digital, analog/digital) converter and a PWM (Pulse width modulation, pulse width modulation) regulator, and the PWM output of the PWM regulator can be passed through MOS (MOSFET, gold). Oxygen half field effect transistor) drive current to control the BOOST unit circuit (a booster circuit), and the output of the BOOST unit circuit is connected to the load 40 .

In addition, the tracking device 20 may further include a detection circuit for the output voltage and output current of the photovoltaic assembly 10 to sample the output voltage and output current of the photovoltaic assembly 10 .

As an example, as shown in FIG. 2 , the tracking device 20 may include a voltage detection circuit 1 , a current detection circuit 2 , a photovoltaic controller 3 , a PWM driving circuit 4 and a BOOST circuit 5 . The output terminals of the photovoltaic module 10 are respectively connected to the input terminal of the voltage detection circuit 1 and the input terminal of the current detection circuit 2 . The output terminal of the voltage detection circuit 1 and the output terminal of the current detection circuit 2 are respectively connected to the input terminal of the photovoltaic controller 3 . The photovoltaic controller 3 has A/D conversion and PWM output, and the photovoltaic controller 3 has a built-in maximum power point tracking control algorithm program. The PWM output of the photovoltaic controller 3 controls the BOOST circuit 5 through the PWM drive circuit 4 to complete the maximum power point tracking algorithm program under complex conditions.

As an example, the tracking device 20 may be a DC/DC (Direct current/Direct current, direct current/direct current) converter, and the DC/DC converter is further used to convert the electrical energy output by the photovoltaic module 10 into energy required by the load 40 .

The load 40 may be a rechargeable battery or other loads, which are not limited in this embodiment of the present application. The rechargeable battery may be a lithium battery or the like.

In addition, please refer to FIG. 1 , the DC bus 30 can also be connected to the rechargeable battery 50 to charge the rechargeable battery 50 . As shown in FIG. 1 , the rechargeable battery 50 may be a lithium battery, and of course other rechargeable batteries, which are not limited in this embodiment of the present application.

Next, the application scenarios of the embodiments of the present application are introduced.

At present, the commonly used maximum power point tracking algorithms are mainly disturbance observation method and conductance increment method. The perturbation observation method realizes MPPT by comparing the variation of instantaneous conductance of photovoltaic modules. Fig. 3 is a schematic diagram of the P-U characteristic curve of a photovoltaic module provided by the embodiment of the present application. It can be seen from Fig. 3 that when the P-U characteristic curve is a single peak, the maximum power point is at the apex, so for any arbitrary value on the P-U characteristic curve The point satisfies the following formula (1):

Due to the need for integral operation in the actual system, the computing power of the processor is relatively high. Therefore, in the actual system, ΔP and ΔU are often used to replace the corresponding dP and dU, and ΔP/ΔU is used instead of dP/dU to judge the direction of the interference. To reduce the amount of calculation, the control flow chart 4 of the conventional conductance incremental method is shown.

As shown in Figure 4, the conventional maximum power point tracking process of the conductance incremental method mainly includes: sampling the output voltage and output current of photovoltaic modules in real time, obtaining U(k) and I(k), and calculating the Real-time output power P(k)=U(k)×I(k). Obtain U(k-1) and I(k-1) obtained by sampling the output voltage and output current of the photovoltaic module at the last sampling time, and the output power of the photovoltaic module P(k-1)=U(k-1 )×I(k-1). Then, calculate the voltage variation ΔU=U(k)-U(k-1) at the current moment relative to the previous moment, and the power variation ΔP=P(k)-P(k-1). After that, it is judged whether ΔP/ΔU is greater than 0. If △P/△U is greater than 0, let Uref=Uref+step; if △P/△U is equal to 0, let Uref=Uref; if △P/△U is less than 0, let Uref=Uref-step, where step represents the perturbation step size.

The conventional conductance incremental method is a fixed-step conductance incremental method, which has the problem of selecting the perturbation step, which affects the tracking effect of the maximum power point. If the selected disturbance step size is too small, the tracking time of the maximum power point may be too long, which affects the stability of the photovoltaic system. If the selected disturbance step size is too large, although the tracking time of the maximum power point will be shortened, it may cause the deviation of the photovoltaic system in the steady state to be too large, that is, the deviation between the tracked maximum power point and the actual maximum power point is relatively large. large, affecting the utilization rate of photovoltaic power generation. In order to improve the tracking effect of the maximum power point, the embodiment of the present application proposes a maximum power point tracking method with variable step size. The specific implementation process will be described in detail in the following embodiment of FIG. 5 .

FIG. 5 is a flowchart of a maximum power point tracking method provided by an embodiment of the present application. The method can be applied to the tracking device 20 in the above-mentioned FIG. 1 , for example, applied to the photovoltaic controller 21 in the tracking device 20 , as shown in FIG. 5 As shown, the method may include the following steps:

Step 501: Sampling the output voltage and output current of the photovoltaic module to obtain the first output voltage and the first output current at the current sampling time.

In the embodiment of the present application, the real-time output voltage and real-time output current of the photovoltaic module may be sampled during the working process of the photovoltaic module. The first output voltage and the first output current are the output voltage and the output current at the current sampling time, respectively.

As an example, the output voltage and output current of the photovoltaic module may be sampled every preset time period, and the output voltage and output current sampled at the current moment are used as the first output voltage and the first output current. The preset duration may be preset, for example, the preset duration may be 1 second or 2 seconds.

As an example, as shown in FIG. 2 , the output voltage and output current of the photovoltaic module can be sampled by the voltage detection circuit 1 and the current detection circuit 2 respectively.

As an example, in the process of sampling the output voltage and output current of the photovoltaic module, the output voltage and output current obtained by each sampling and the output power calculated according to the output voltage and output current may be stored, for example, stored in in the database.

Step 502: Calculate the first output power at the current sampling time according to the first output voltage and the first output current.

Wherein, the first output voltage may be multiplied by the first output current to obtain the first output power. For example, the first output voltage is represented by U(k), the first output current is represented by I(k), and the first output power is represented by P(k), where P(k)=U(k)×I(k).

Step 503: Obtain the second output voltage and the second output power at the last sampling time, and calculate the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power.

Wherein, the second output voltage and the second output power are the output voltage and output current sampled at the last moment, respectively. For example, the output voltage and output current of the photovoltaic module may be sampled every preset time period, and the last sampling time is the time before the current sampling time that is separated by the preset time period.

The second output power is obtained by multiplying the second output voltage by the second output current at the last sampling time. For example, the second output voltage and the second output current at the last sampling time may be acquired, and then the second output voltage and the second output current are multiplied to obtain the second output power. For example, the second output voltage is represented by U(k-1), the second output current is represented by I(k-1), the second output power is represented by P(k-1), and P(k-1)=U( k-1)×I(k-1).

Wherein, the second output voltage and the second output power at the last sampling time can be obtained from the stored sampling data. For example, the second output voltage and the second output power at the last sampling time are obtained from the database.

After acquiring the second output voltage and the second output power, the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power may be calculated.

For example, the voltage difference is represented by ΔU, ΔU=U(k)-U(k-1). The power difference is represented by ΔP, ΔP=P(k)-P(k-1).

Step 504: Determine the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference.

The reference voltage of the maximum power point is used to indicate the maximum power point, and the photovoltaic module operates according to the reference voltage of the maximum power point, so that the output power of the photovoltaic module can work at the maximum power point.

As an example, the operation of determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference includes: judging whether the ratio of the power difference to the voltage difference is greater than a preset ratio. If the ratio of the power difference to the voltage difference is greater than the preset ratio, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module is determined as the first disturbance direction. If the ratio of the power difference to the voltage difference is smaller than the preset ratio, the disturbance direction of the reference voltage at the maximum power point of the photovoltaic module is determined as the second disturbance direction. If the ratio of the power difference to the voltage difference is equal to the preset ratio, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module is determined as the first disturbance direction, or it is determined that the reference voltage of the maximum power point of the photovoltaic module does not need to be disturbed. .

The preset ratio can be preset, and is usually set to a smaller value. For example, the preset ratio is 0 or 0.1, etc. The first disturbance direction refers to the direction in which the reference voltage of the maximum power point needs to be increased, and the second disturbance direction refers to the direction in which the reference voltage of the maximum power point needs to be decreased.

Please refer to FIG. 6 . FIG. 6 is a schematic logical diagram of a maximum power point tracking method provided by an embodiment of the present application. As shown in Figure 6, after calculating ΔU=U(k)-U(k-1), ΔP=P(k)-P(k-1), determine the ratio of power difference to voltage difference ΔP/ Whether △U is greater than 0. If the judgment result is yes, the disturbance direction is determined as the first disturbance direction, that is, the reference voltage of the maximum power point needs to be increased. If the judgment result is no, continue to judge whether ΔP/ΔU is equal to 0. If the judgment result is yes, the disturbance direction is determined as the first disturbance direction, that is, the reference voltage of the maximum power point needs to be increased. If the judgment result is no, it is determined that the disturbance direction is the second disturbance direction, that is, the reference voltage of the maximum power point needs to be reduced.

Step 505: Determine the target disturbance step size according to the absolute value of the power difference.

In this embodiment of the present application, the target disturbance step size may be determined according to the absolute value of the power difference. If the absolute value of the power difference at different sampling times relative to the previous sampling time is different, the corresponding target disturbance step size is also different, thus providing a variable-step conductance increment method to track the maximum power point of the photovoltaic module.

Among them, the target disturbance step size is related to the absolute value of the power difference between the current sampling time and the previous sampling time. For example, the target perturbation step size can be positively correlated with the absolute value of the power difference. In this way, if the absolute value of the power difference is small, the corresponding target disturbance step size setting is also small, so that the maximum power point can be accurately tracked when the power change is small, and the maximum power point deviation when the photovoltaic system is stable is reduced. . If the absolute value of the power difference is large, the corresponding target disturbance step size setting is also large, so that when the power changes greatly, that is, when the environment fluctuates in distance, the maximum power point can be quickly tracked and the tracking time of the maximum power point can be saved.

As an example, multiple hysteresis intervals can be set in advance for the absolute value of the power difference, and different hysteresis intervals correspond to different disturbance step sizes. The function of setting multiple hysteresis intervals in this application is to prevent the threshold from being set too close. This causes the photovoltaic controller to switch repeatedly in adjacent working areas. More specifically, the hysteresis interval represents a working interval of the photovoltaic controller, and corresponding operations are performed in different working intervals. During the maximum power point tracking process, the target disturbance step length is determined according to the disturbance step length corresponding to the hysteresis interval to which the absolute value of the power difference between the current sampling time and the previous sampling time belongs.

For example, the hysteresis interval may include at least two of the first hysteresis interval, the second hysteresis interval and the third hysteresis interval. The first hysteresis interval is [0, a], the second hysteresis interval is [a1, b], and the third hysteresis interval is [b1, ∞]. where 0<a1<a<b1<b.

The first hysteresis interval corresponds to the first disturbance step size, the second hysteresis interval corresponds to the second disturbance step size, and the third hysteresis interval corresponds to the third disturbance step size. The sizes of the first disturbance step size, the second disturbance step size and the third disturbance step size can be set as required, for example, the first disturbance step size < the second disturbance step size < the third disturbance step size. For example, the first perturbation step, the second perturbation step and the third perturbation step can be represented by step1, step2 and step3, respectively.

The hysteresis interval can be indicated by the hysteresis interval identifier, and the hysteresis interval indicated by the hysteresis interval is different if the values of the hysteresis interval identifier are different. For example, the value of the hysteresis interval identifier of the first hysteresis interval is X, the value of the hysteresis interval identifier of the second hysteresis interval is Y, the value of the hysteresis interval identifier of the third hysteresis interval is Z, and X<Y <Z. In addition, the initial value of the hysteresis interval identifier may be X.

For example, the hysteresis interval identifier may be step_flag, where X is 0, Y is 1, and Z is 2. If step_flag=0, step_flag is used to indicate the first hysteresis interval. If step_flag=1, step_flag is used to indicate the second hysteresis interval. If step_flag=2, step_flag is used to indicate the third hysteresis interval.

As an example, the operation of determining the target disturbance step size according to the absolute value of the power difference may include: acquiring a backlash interval identifier; judging whether the absolute value of the power difference falls within the backlash interval corresponding to the backlash interval identifier, and if so, not updating The hysteresis interval identifier, if not, update the hysteresis interval identifier according to the hysteresis interval corresponding to the absolute value of the power difference; obtain the disturbance step size corresponding to the hysteresis interval identifier, and use the hysteresis interval identifier corresponding to the disturbance step size for the target perturbation step size.

The disturbance step size corresponding to the hysteresis interval identifier refers to the disturbance step size corresponding to the hysteresis interval indicated by the hysteresis interval identifier. The acquired hysteresis interval identifier is used to indicate the hysteresis interval to which the absolute value of the power difference at the last sampling time belongs. In this way, the target hysteresis interval of the absolute value of the power difference at the current sampling moment can be determined according to the absolute value of the power difference at the current sampling moment and the hysteresis interval to which the absolute value of the power difference at the previous sampling moment belongs.

For example, after obtaining the hysteresis interval identifier, the target hysteresis interval of the absolute value of the power difference can be determined according to the absolute value of the power difference and the hysteresis interval identifier, and the hysteresis interval identifier can be updated according to the target hysteresis interval. After that, the disturbance step size corresponding to the target hysteresis interval is obtained, and the disturbance step size corresponding to the target hysteresis interval is used as the target disturbance step size.

That is, after determining the target hysteresis interval of the absolute value of the power difference at the current sampling moment, the hysteresis interval identifier can also be updated according to the target hysteresis interval of the absolute value of the power difference at the current sampling moment, so that The updated hysteresis interval identifier is used to indicate the target hysteresis interval of the absolute value of the power difference at the current sampling moment, so that after obtaining the hysteresis interval identifier at the next sampling moment, the absolute value of the power difference at the next sampling moment and The target hysteresis interval of the absolute value of the power difference at the current sampling moment is used to determine the target hysteresis interval of the absolute value of the power difference at the next sampling moment.

In a possible implementation manner, the hysteresis interval identifier may be stored in a specified storage space, and when the hysteresis interval identifier needs to be acquired, the hysteresis interval identifier may be read from the specified storage space. The hysteresis interval identifier may be preset as an initial value. Afterwards, in the process of maximum power point tracking, the hysteresis interval identifier may be updated according to the hysteresis interval to which the absolute value of the power difference corresponding to each sampling moment belongs.

As an example, the hysteresis interval includes a first hysteresis interval, a second hysteresis interval, and a second hysteresis interval, the first hysteresis interval is [0, a], and the second hysteresis interval is [a1, b] , the third hysteresis interval is [b1, ∞]; the first hysteresis interval corresponds to the first disturbance step, the second hysteresis interval corresponds to the second disturbance step, and the third hysteresis interval corresponds to the third disturbance step, so When the value of the hysteresis interval identifier of the first hysteresis interval is X, the value of the hysteresis interval identifier of the second hysteresis interval is Y, and the value of the hysteresis interval identifier of the third hysteresis interval is Z, it is judged that Whether the absolute value of the power difference falls within the hysteresis interval corresponding to the hysteresis interval identifier, if so, the hysteresis interval identifier is not updated; if not, the operation of updating the hysteresis interval identifier according to the hysteresis interval corresponding to the absolute value of the power difference Can include the following steps:

1) Determine whether the absolute value of the power difference is less than or equal to a.

Please refer to FIG. 6 , after it is determined that ΔP/ΔU>0, or after it is determined that ΔP/ΔU is not equal to 0, it can be first determined whether |ΔP| is less than or equal to a.

2) If the absolute value of the power difference is less than or equal to a, then judge whether the value of the hysteresis interval is greater than or equal to Y.

The value of the hysteresis interval identifier is used to indicate the hysteresis interval of the absolute value of the power difference at the first sampling time. If the value of the hysteresis interval identifier is X, the hysteresis interval identifier is used to indicate the first hysteresis interval; if the hysteresis interval identifier is Y, the hysteresis interval identifier is used to indicate the second hysteresis interval; The identifier is Z; then the hysteresis interval identifier is used to indicate the third hysteresis interval.

Please refer to FIG. 6 , take step_flag as the hysteresis interval identifier, X=0, Y=1, Z=2 as an example, if step_flag=0, step_flag is used to indicate the first hysteresis interval [0, a]. If step_flag=1, step_flag is used to indicate the second hysteresis interval [a1, b]. If step_flag=2, step_flag is used to indicate the third hysteresis interval [b1, ∞]. If |ΔP|≤a, judge whether the value of step_flag is ≥1.

3) If the hysteresis interval identifier is less than Y, determine that the absolute value of the power difference belongs to the first hysteresis interval, and update the value of the hysteresis interval identifier to X.

Referring to FIG. 6 , if step_flag is not greater than or equal to 1, it is determined that |ΔP| belongs to the first hysteresis interval [0, a], and the value of step_flag is updated to 0, that is, step_flag=0.

4) If the hysteresis interval identifier is greater than or equal to Y, determine whether the absolute value of the power difference is less than a1.

Please refer to FIG. 6 , if step_flag≥1, continue to judge whether |ΔP| is less than a1.

5) If the absolute value of the power difference is less than a1, it is determined that the absolute value of the power difference belongs to the first hysteresis interval, and the value of the hysteresis interval is updated to X. In this application, the absolute value of the power difference belongs to a certain hysteresis interval. Hysteresis interval, indicating that the absolute value of the power difference falls within the range of a certain hysteresis interval.

Referring to FIG. 6 , if |ΔP|<a1, it is determined that |ΔP| belongs to the first hysteresis interval [0, a], and the value of step_flag is updated to 0, that is, step_flag=0.

6) If the absolute value of the power difference is not less than a1, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value identified by the hysteresis interval is updated to Y.

Please refer to FIG. 6 , if |ΔP| is not less than a1, that is, |ΔP|≥a1, then it is determined that |ΔP| belongs to the second hysteresis interval [a1, b], and the value of step_flag is updated to Y, that is, step_flag=0 .

7) After step 1), if the determination result is that the absolute value of the power difference is greater than a, then determine whether the hysteresis interval identifier is equal to X.

Please refer to FIG. 6 , if |ΔP| is not less than or equal to a, that is, |ΔP|>a, it is determined whether step_flag is equal to 0.

8) If the hysteresis interval identifier is equal to X, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value of the hysteresis interval identifier is updated to Y.

Referring to FIG. 6 , if step_flag=0, it is determined that |ΔP| belongs to the second hysteresis interval [a1, b], and the value of step_flag is updated to 1, that is, step_flag=1.

9) If the hysteresis interval identifier is not equal to X, determine whether the hysteresis interval identifier is equal to Y.

Please refer to FIG. 6 , if step_flag is not=0, that is, step_flag=1 or 2, continue to judge whether step_flag=1.

10) If the hysteresis interval identifier is equal to Y, then judge whether the absolute value of the power difference is greater than b; if the absolute value of the power difference is greater than b, then determine that the absolute value of the power difference belongs to the third hysteresis interval, and identify the hysteresis interval. The value of is updated to Z; if the absolute value of the power difference is less than or equal to b, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value identified by the hysteresis interval is updated to Y.

Please refer to FIG. 6 , if step_flag=1, it is determined whether |ΔP| is greater than b. If |ΔP|>b, it is determined that |ΔP| belongs to the third hysteresis interval [b1, ∞], and the value of step_flag is updated to 2, that is, step_flag=2. If |ΔP| is not greater than b, that is, |ΔP|≤b, it is determined that |ΔP| belongs to the second hysteresis interval [a1, b], and the value of step_flag is updated to 1, that is, step_flag=1.

11) If the hysteresis interval identifier is not equal to Y, then judge whether the absolute value of the power difference is greater than b1; if the absolute value of the power difference is not greater than b1, then determine that the absolute value of the power difference belongs to the second hysteresis interval, and the second The value of the hysteresis interval identifier at time is updated to Y; if the absolute value of the power difference is greater than b1, it is determined that the absolute value of the power difference belongs to the third hysteresis interval, and the value of the hysteresis interval identifier is updated to Z.

Referring to FIG. 6 , if step_flag is not equal to 1, that is, step_flag=2, it is determined whether |ΔP| is greater than b1. If |ΔP|>b1, it is determined that |ΔP| belongs to the third hysteresis interval [b1, ∞], and the value of step_flag is updated to 2, that is, step_flag=2. If |ΔP| is not greater than b1, that is, |ΔP|≤b1, it is determined that |ΔP| belongs to the second hysteresis interval [a1, b], and the value of step_flag is updated to 1, that is, step_flag=1.

After the target hysteresis interval of the absolute value of the power difference is determined, and the hysteresis interval identifier is updated according to the target hysteresis interval, the disturbance step size corresponding to the target hysteresis interval can be obtained. as the target perturbation step size.

For example, if the target hysteresis interval is the first hysteresis interval, the first disturbance step size corresponding to the first hysteresis interval is used as the target disturbance step size. If the target hysteresis interval is the second hysteresis interval, the second disturbance step size corresponding to the second hysteresis interval is used as the target disturbance step size. If the target hysteresis interval is the third hysteresis interval, the third disturbance step size corresponding to the third hysteresis interval is used as the target disturbance step size.

For example, please refer to FIG. 6 , step_flag=0 corresponds to step1, step_flag=1 corresponds to step2, and step_flag=2 corresponds to step3.

Step 506: According to the disturbance direction and the target disturbance step size, update the reference voltage of the maximum power point of the photovoltaic module, so that the photovoltaic module operates according to the updated reference voltage.

For example, if the disturbance direction is the first disturbance direction, the reference voltage of the maximum power point is increased by the target disturbance step size. If the disturbance direction is the second disturbance direction, the reference voltage of the maximum power point is reduced by the target disturbance step size. In addition, if the ratio of the power difference to the voltage difference is equal to the preset ratio, the reference voltage of the maximum power point is not updated, or the reference voltage of the maximum power point is increased by the first disturbance step size.

Among them, the reference voltage of the maximum power point can be represented by Uref. Please refer to FIG. 6 , in the case of ΔP/ΔU>0, if step_flag=0, let Uref=Uref+step1; if step_flag=1, let Uref=Uref+step2; if step_flag=2, let Uref=Uref+step3.

As an example, the reference voltage of the maximum power point can be updated by adjusting the duty cycle of the PWM according to the disturbance direction and the target disturbance step size, so that the photovoltaic module operates according to the updated reference voltage.

In this embodiment of the present application, the output voltage and output current of the photovoltaic module can be sampled to obtain the first output voltage and the first output current, and the first output power at the current sampling time can be calculated according to the first output voltage and the first output current, and Obtain the second output voltage and the second output power at the last sampling time, and calculate the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power. Then, according to the ratio of the power difference to the voltage difference, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module is determined, and the target disturbance step size is determined according to the absolute value of the power difference. After that, according to the disturbance direction and the target disturbance step size, the reference voltage of the maximum power point of the photovoltaic module is updated, so that the photovoltaic module operates according to the updated reference voltage. In this way, by determining the target disturbance step size according to the absolute value of the power difference, a conductance increment method with variable step size is provided to track the maximum power point of the photovoltaic module, which can improve the tracking effect of the maximum power point.

In addition, since the photovoltaic system may have partial shading of photovoltaic modules, the P-U characteristic curve of the photovoltaic module may appear multi-peak phenomenon as shown in Figure 7. The P-U characteristic curve shown in Figure 7 has multiple peak points. They are MPP1, MPP2, and MPP3, respectively. When the P-U characteristic curve has multiple peaks, there are multiple peak points in the P-U characteristic curve. In this case, the conventional conductance incremental method can only track the peak point with the smallest peak value, but cannot track the peak point with the largest peak value. That is, the global maximum power point cannot be tracked. As shown in Figure 7, the conventional conductance increment method can only track MPP1, but not MPP2 and MPP3.

In this embodiment of the present application, in order to ensure that the global maximum power point can be tracked, a method is provided for first searching for the global maximum power point, and then tracking the maximum power point according to the method shown in the above-mentioned embodiment of FIG. 5 . The specific implementation process is as follows: This is explained in detail in the embodiment of FIG. 8 below.

FIG. 8 is a flowchart of another maximum power point tracking method provided by an embodiment of the present application. The method can be applied to the tracking device 20 in FIG. 1 , such as the photovoltaic controller 21 in the tracking device 20 , as shown in FIG. 8 As shown, the method may include the following steps:

Step 801: Set the reference voltage to be determined as the open circuit voltage of the photovoltaic module.

Wherein, the reference voltage of the maximum power point of the photovoltaic module to be determined. The open-circuit voltage of the photovoltaic module refers to the terminal voltage of the photovoltaic module in the open-circuit state.

In the embodiment of the present application, the open-circuit voltage of the photovoltaic assembly may be determined first, and the open-circuit voltage of the photovoltaic assembly may be used as the reference voltage to be determined.

For example, the reference voltage to be determined can be represented by Uref_search, and the open circuit voltage of the photovoltaic module can be represented by Uoc. Please refer to FIG. 9 , first set Uref_search=Uoc.

Step 802: Gradually reduce the reference voltage to be determined according to the preset disturbance step size, and record the output voltage, output current and output power of the photovoltaic module, obtain the maximum output power among all the recorded output powers, and use the output corresponding to the maximum output power. The voltage is used as the reference voltage of the maximum power point of the photovoltaic module.

The preset step size may be preset, for example, may be set to 1% of the open circuit voltage.

In the embodiment of the present application, the reference voltage that can be disturbed is sequentially reduced by the preset step size, and in the process of decreasing the disturbed reference voltage in turn, the maximum output power of the photovoltaic module, that is, the global maximum power, is searched, and then the maximum output power of the photovoltaic module can be searched. The output voltage at the output power is set as the reference voltage at the maximum power point.

As an example, step 802 can be implemented through the following steps 1)-6):

1) Decrease the reference voltage to be determined by the preset disturbance step size.

The preset disturbance step size may be preset. The preset disturbance step size can be represented by Δstep.

Referring to FIG. 9, Uref_search=Uref_search-Δstep can be set.

2) Determine whether the reduced reference voltage to be determined is less than a preset ratio of the open circuit voltage, and the preset ratio is less than 1.

The preset ratio may be preset, for example, the preset ratio may be 0.2 or 0.3.

Referring to FIG. 9 , it can be determined whether Uref_search is less than 0.2×Uoc.

3) If the reduced reference voltage to be determined is not less than the preset ratio of the open circuit voltage, sample the output voltage and output current of the photovoltaic module, and calculate the output power.

Please refer to Figure 9, if the judgment result is no, that is, Uref_search is not less than 0.2×Uoc, sample the real-time output voltage U(m) and real-time output current I(m) of the photovoltaic module, and calculate the output power P(m)=U (m)×I(m).

4) Determine whether the output power is greater than the historical maximum output power, which is the maximum output power determined according to the sampled output voltage and output current in the process of gradually reducing the reference voltage to be determined.

The initial value of the historical maximum output power can be set to 0. The historical maximum output power can be represented by P_max.

Please refer to FIG. 9 , after sampling U(m) and I(m), the output power of the photovoltaic module P(m)=U(m)×I(m) can be calculated. Then, it is judged whether or not P(m) is greater than P_max.

5) If the output power is greater than the historical maximum output power, update the historical maximum output power to the output power, and use the reduced reference voltage to be determined as the reference voltage to be determined, return to step 1), and continue to reduce the to-be-determined reference voltage. Determine the reference voltage.

Please refer to FIG. 9, if the judgment result is yes, that is, P(m)>P_max, then let P_max=P(m), and let the reference voltage Uref=U(m) of the maximum power point, and then return to step 1), Continue to execute the steps and subsequent steps that make Uref_search=Uref_search-Δstep.

6) If the output power is not greater than the historical output power, return to step 1) and continue to reduce the reference voltage to be determined.

Referring to FIG. 9 , if the judgment result is no, that is, P(m) is not greater than P_max, then return to step 1), and continue to execute the steps of Uref_search=Uref_search-Δstep and subsequent steps.

7) If the reduced reference voltage to be determined is smaller than the preset ratio of the open circuit voltage, the output voltage corresponding to the historical maximum output power is used as the reference voltage of the maximum power point.

Please refer to Figure 9, if Uref_search<0.2×Uoc, you can stop the search, directly set Uref=U(m) corresponding to P_max, and then perform the maximum power point tracking according to the Uref at this time, that is, execute the above diagram according to the Uref at this time. 6 shows the maximum power point tracking process.

Step 803: Sampling the output voltage and output current of the photovoltaic module, the first output voltage and the first output current at the current sampling time.

Step 804: Calculate the first output power at the current sampling time according to the first output voltage and the first output current.

Step 805: Obtain the second output voltage and the second output power at the last sampling time, and calculate the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power.

Step 806: Determine the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference.

Step 807: Determine the target disturbance step size according to the absolute value of the power difference.

Step 808: According to the disturbance direction and the target disturbance step size, update the reference voltage of the maximum power point of the photovoltaic module, so that the photovoltaic module operates according to the updated reference voltage.

It should be noted that the implementation process of step 803-step 808 is the same as the above-mentioned step 501-step 506, and the specific implementation process can refer to the relevant description of the above-mentioned step 501-step 506, which is not limited in this embodiment of the present application.

In the embodiment of the present application, by setting the reference voltage to be determined as the open-circuit voltage of the photovoltaic module, then gradually reducing the reference voltage to be determined according to the preset disturbance step size, and recording the output voltage, output current and output power of the photovoltaic module to obtain The maximum output power among all the recorded output powers, and the output voltage corresponding to the maximum output power is used as the reference voltage of the maximum power point of the photovoltaic module. The global maximum power point can be searched, which is convenient for subsequent fast tracking to the maximum power point, which improves the tracking Maximum power point efficiency, saving tracking time.

In addition, in the photovoltaic system, due to the randomness, finiteness and intermittency of the photovoltaic system, it is difficult to charge photovoltaic energy according to a specific charging law. Among the commonly used battery charge and discharge control strategies, one type does not consider the stability of the DC bus, and the Such methods are detrimental to the stability and safety of independently operating lithium battery systems. The other type considers the stability of the DC bus, but for photovoltaic systems, this type of strategy cannot achieve maximum power tracking; or it is implemented by the control circuit of lithium batteries, which can achieve maximum power tracking, but cannot be used for charging voltage and current. Control, shorten the service life of the lithium battery.

Based on the staged charging strategy of lithium batteries, combined with the characteristics of photovoltaic modules for power generation, and with the maximum power tracking control of photovoltaic modules, the embodiment of the present application proposes a charging method that combines maximum power charging and staged charging, which can The above purpose is achieved while ensuring the stability of the DC bus voltage, so that the charging and discharging process of the lithium battery is suitable for an independent photovoltaic system. The specific implementation process will be described in detail in the embodiment of FIG. 10 below.

FIG. 10 is a flowchart of a charging control method provided by an embodiment of the present application. The method can be applied to the tracking device 20 in FIG. 1 , such as the photovoltaic controller 21 in the tracking device 20 . As shown in FIG. 10 , the The method may include the following steps:

Step 1001 : in response to the charging request operation, obtain request parameters of the charging request operation, where the request parameters include a request voltage and a request current.

As an example, when the rechargeable battery needs to be charged, the request parameter can be sent to the photovoltaic controller through the BMS circuit or related software. Wherein, the rechargeable battery may be a lithium battery or the like.

Step 1002: Obtain output parameters of the photovoltaic module, and compare the request parameters with the output parameters, where the output parameters include output voltage and output current.

As an example, both ends of the DC bus are connected to the photovoltaic module and the rechargeable battery, respectively, the output voltage of the photovoltaic module may be the bus voltage of the DC bus, and the output current of the photovoltaic module may be the bus current of the DC bus.

Step 1003: Determine whether the requested voltage is less than the output voltage.

Step 1004: If the requested voltage is less than the output voltage, control the photovoltaic module to operate in a constant voltage output mode.

If the requested voltage is less than the output voltage, it means that the rechargeable battery is about to be fully charged to reach the overcharge voltage. In this case, the photovoltaic module can be controlled to operate in constant voltage output mode. In this constant voltage output mode, the rechargeable battery can accept the output of the photovoltaic module. constant voltage for voltage-limited charging.

Step 1005: If the requested voltage is greater than or equal to the output voltage, determine whether the requested current is less than the output current.

Step 1006: If the requested current is greater than or equal to the output current, control the photovoltaic module to operate in the maximum power point tracking mode.

If the requested voltage is greater than or equal to the output voltage, and the requested current is greater than or equal to the output current, it means that the rechargeable battery can control the photovoltaic modules to run in the maximum power point tracking mode to maximize the use of solar energy. In this case, the photovoltaic modules can be controlled to operate In the maximum power point tracking mode, and according to the output voltage and current in the maximum power point tracking mode, the rechargeable battery is charged according to the output voltage and output current of the photovoltaic module in the maximum power point tracking mode.

Step 1007 : if the requested voltage is less than the output voltage, control the photovoltaic module to operate in a constant current output mode.

If the requested voltage is greater than or equal to the output voltage, and the requested current is less than the output current, it means that the rechargeable battery has reached the overcharge current. current for current-limited charging.

In the embodiment of the present application, on the basis of the staged charging strategy of lithium batteries, combined with the characteristics of photovoltaic module power generation, and with the maximum power point tracking control of photovoltaic modules, a charging method that combines maximum power charging and staged charging is proposed. The method ensures the stability of the DC bus voltage, so that the charging and discharging process of the rechargeable battery is suitable for the independent photovoltaic system. In the embodiment of the present application, no matter whether the photovoltaic module works in the constant voltage output mode, the maximum power point output mode or the constant current output mode, the output voltage and current cannot exceed the maximum charging voltage and/or the maximum charging current of the rechargeable battery, Moreover, it should be noted that the photovoltaic module operates in constant voltage output mode or constant current output mode, and it can still operate at the maximum power point according to the reference voltage, because the power calculation formula P=U*I, when the output voltage U or output current When I is constant, the output power P can still work at the maximum output point by adjusting the output current I or the output voltage U.

FIG. 11 is a block diagram of a maximum power point tracking device provided by an embodiment of the present application. The device may be implemented by software, hardware, or a combination of the two as part or all of a computer device, and the computer device may be a tracking device or a tracking device. PV controller in the installation. Referring to FIG. 11 , the apparatus includes: a sampling module 1101 , a first processing module 1102 , a second processing module 1103 , a first determination module 1104 , a second determination module 1105 and an update module 1106 .

The sampling module 1101 is used for sampling the output voltage and output current of the photovoltaic module to obtain the first output voltage and the first output current at the current sampling time;

a first processing module 1102, configured to calculate the first output power at the current sampling moment according to the first output voltage and the first output current;

The second processing module 1103 is configured to acquire the second output voltage and the second output power at the last sampling time, calculate the voltage difference between the first output voltage and the second output voltage, and calculate the voltage difference between the first output voltage and the second output power The power difference of the output power;

a first determination module 1104, configured to determine the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference;

The second determination module 1105 is configured to determine the target disturbance step size according to the absolute value of the power difference;

The updating module 1106 is configured to update the reference voltage of the maximum power point of the photovoltaic module according to the disturbance direction and the target disturbance step size, so that the photovoltaic module operates according to the updated reference voltage.

Optionally, the second determining module 1105 includes:

a first obtaining unit, configured to obtain the hysteresis interval identifier;

The updating unit is used for judging whether the absolute value of the power difference falls into the hysteresis interval corresponding to the hysteresis interval identifier, if so, the hysteresis interval identifier is not updated; The hysteresis interval is updated with the hysteresis interval identifier;

The second acquiring unit is configured to acquire the disturbance step size corresponding to the hysteresis interval identifier, and use the disturbance step size corresponding to the hysteresis interval identifier as the target disturbance step size.

Optionally, the hysteresis interval includes a first hysteresis interval and a second hysteresis interval, the first hysteresis interval is [0, a], the second hysteresis interval is [a1, b], and a1<a <b; the first hysteresis interval corresponds to the first disturbance step size, and the second hysteresis interval corresponds to the second disturbance step size; the value of the hysteresis interval identifier of the first hysteresis interval is X, the second hysteresis interval The value of the hysteresis interval identifier of the interval is Y, X<Y;

This update unit is used to:

Determine whether the absolute value of the power difference is less than or equal to a;

If the absolute value of the power difference is less than or equal to a, then determine whether the value of the hysteresis interval is greater than or equal to Y;

If the value of the hysteresis interval identifier is less than Y, then determine that the absolute value of the power difference belongs to the first hysteresis interval, and update the value of the hysteresis interval identifier to X;

If the value of the hysteresis interval is greater than or equal to Y, then judge whether the absolute value of the power difference is less than a1;

If the absolute value of the power difference is less than a1, it is determined that the absolute value of the power difference belongs to the first hysteresis interval, and the value of the hysteresis interval is updated to X;

If the absolute value of the power difference is not less than a1, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value identified by the hysteresis interval is updated to Y.

Optionally, the hysteresis interval further includes a third hysteresis interval, the third hysteresis interval is [b1, ∞], a<b1<b, the third hysteresis interval corresponds to the third disturbance step size, and the third hysteresis interval corresponds to the third disturbance step size. The value of the hysteresis interval identifier of the three hysteresis intervals is Z, Y<Z, and the update unit is also used for:

If the absolute value of the power difference is greater than a, then determine whether the value of the hysteresis interval identifier is equal to X;

If the value of the hysteresis interval identifier is equal to X, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value of the hysteresis interval identifier is updated to Y;

If the value of the hysteresis interval identifier is not equal to X, determine whether the value of the hysteresis interval identifier is equal to Y;

If the value of the hysteresis interval is equal to Y, then judge whether the absolute value of the power difference is greater than b; if the absolute value of the power difference is greater than b, then determine that the absolute value of the power difference belongs to the third hysteresis interval, and set the The value of the hysteresis interval identifier is updated to Z; if the absolute value of the power difference is not greater than b, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value of the hysteresis interval identifier is updated to Y;

If the value of the hysteresis interval identifier is not equal to Y, judge whether the absolute value of the power difference is greater than b1; if the absolute value of the power difference is not greater than b1, then determine that the absolute value of the power difference belongs to the second hysteresis interval , the value of the hysteresis interval is updated to Y; if the absolute value of the power difference is greater than b1, it is determined that the absolute value of the power difference belongs to the third hysteresis interval, and the value of the hysteresis interval is updated to Z .

Optionally, the first determining module 1104 is used for:

If the ratio of the power difference to the voltage difference is greater than the preset ratio, determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module as the first disturbance direction;

If the ratio of the power difference to the voltage difference is smaller than the preset ratio, determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module as the second disturbance direction;

The updating the reference voltage of the maximum power point of the photovoltaic module according to the disturbance direction and the target disturbance step, including:

If the disturbance direction is the first disturbance direction, increasing the reference voltage of the maximum power point by the target disturbance step;

If the disturbance direction is the second disturbance direction, the reference voltage of the maximum power point is reduced by the target disturbance step size.

Optionally, the device also includes:

a setting module for setting the reference voltage to be determined as the open-circuit voltage of the photovoltaic module;

The third obtaining module is configured to gradually reduce the reference voltage to be determined according to the preset disturbance step size, and record the output voltage, output current and output power of the photovoltaic module, and obtain the maximum output power among all the recorded output powers, so as to obtain the maximum output power. The output voltage corresponding to the maximum output power is used as the reference voltage of the maximum power point of the photovoltaic module.

Optionally, the third acquisition module is used to:

Decrease the to-be-determined reference voltage by a preset disturbance step size;

judging whether the reduced reference voltage to be determined is less than a preset ratio of the open-circuit voltage, where the preset ratio is less than 1;

If the reduced reference voltage to be determined is not less than the preset ratio of the open-circuit voltage, sampling the output voltage and output current of the photovoltaic module, and calculating the output power;

Judging whether the output power is greater than the historical maximum output power, the historical maximum output power is the maximum output power determined according to the sampled output voltage and output current in the process of gradually reducing the reference voltage to be determined;

If the output power is greater than the historical maximum output power, update the historical maximum output power to the output power, use the reduced reference voltage to be determined as the reference voltage to be determined, and return to execute the reduction of the reference voltage to be determined. The step of reducing the preset disturbance step size; if the output power is not greater than the historical output power, return to the step of reducing the to-be-determined reference voltage by the preset disturbance step size;

If the reduced reference voltage to be determined is smaller than the preset ratio of the open circuit voltage, the output voltage corresponding to the historical maximum output power is used as the reference voltage of the maximum power point of the photovoltaic module.

In this embodiment of the present application, the output voltage and output current of the photovoltaic module can be sampled to obtain the first output voltage and the first output current, and the first output power at the current sampling time can be calculated according to the first output voltage and the first output current, and Obtain the second output voltage and the second output power at the last sampling time, and calculate the voltage difference between the first output voltage and the second output voltage, and the power difference between the first output power and the second output power. Then, according to the ratio of the power difference to the voltage difference, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module is determined, and the target disturbance step size is determined according to the absolute value of the power difference. After that, according to the disturbance direction and the target disturbance step size, the reference voltage of the maximum power point of the photovoltaic module is updated, so that the photovoltaic module operates according to the updated reference voltage. In this way, by determining the target disturbance step size according to the absolute value of the power difference, a conductance increment method with variable step size is provided to track the maximum power point of the photovoltaic module, which can improve the tracking effect of the maximum power point.

It should be noted that: when the MPPT device provided in the above embodiment performs MPPT, only the division of the above functional modules is used as an example for illustration. In practical applications, the above functions may be allocated by different The function module is completed, that is, the internal structure of the device is divided into different function modules, so as to complete all or part of the functions described above.

The functional units and modules in the above embodiments may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit, and the above-mentioned integrated units may adopt hardware. It can also be implemented in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing from each other, and are not used to limit the protection scope of the embodiments of the present application.

The maximum power point tracking device and the maximum power point tracking method embodiments provided by the above embodiments belong to the same concept. Repeat.

FIG. 12 is a schematic structural diagram of a computer device provided by an embodiment of the present application. As shown in FIG. 12, the computer device 12 includes: a processor 120, a memory 121, and a computer program 122 stored in the memory 121 and running on the processor 120. When the processor 120 executes the computer program 122, the above-mentioned embodiments are implemented. Steps in the maximum power point tracking method.

Computer device 12 may be a general purpose computer device or a special purpose computer device. In a specific implementation, the computer device 12 may be a desktop computer, a portable computer, a network server, a palmtop computer, a mobile phone, a tablet computer, a wireless terminal device, a communication device or an embedded device, and the embodiment of the present application does not limit the type of the computer device 12 . Those skilled in the art can understand that FIG. 12 is only an example of the computer device 12, and does not constitute a limitation to the computer device 12. It may include more or less components than the one shown, or combine some components, or different components , for example, it may also include input and output devices, network access devices, and so on.

The processor 120 may be a central processing unit (Central Processing Unit, CPU), and the processor 120 may also be other general-purpose processors, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC) , Off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or it may be any conventional processor.

The memory 121 may in some embodiments be an internal storage unit of the computer device 12 , such as a hard disk or memory of the computer device 12 . The memory 121 may also be an external storage device of the computer device 12 in other embodiments, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) equipped on the computer device 12 Cards, Flash Cards, etc. Further, the memory 121 may also include both an internal storage unit of the computer device 12 and an external storage device. The memory 121 is used to store an operating system, application programs, a boot loader (Boot Loader), data, and other programs. The memory 121 may also be used to temporarily store data that has been output or will be output.

Embodiments of the present application further provide a computer device, the computer device comprising: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, the processor executing the computer program The steps in any of the foregoing method embodiments are implemented at the same time.

Embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the steps in the foregoing method embodiments can be implemented.

The embodiments of the present application provide a computer program product, which, when running on a computer, enables the computer to execute the steps in the foregoing method embodiments.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the above-mentioned embodiments, those of ordinary skill in the art should understand that: it can still be used for the above-mentioned implementations. The technical solutions described in the examples are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the application, and should be included in the within the scope of protection of this application.

Claims (10)

1. a maximum power point tracking method, is characterized in that, comprises: sampling the output voltage and output current of the photovoltaic module to obtain the first output voltage and the first output current at the current sampling time; Calculate the first output power at the current sampling moment according to the first output voltage and the first output current; Obtain the second output voltage and the second output power at the last sampling time, calculate the voltage difference between the first output voltage and the second output voltage, and the power of the first output power and the second output power Difference; determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module according to the ratio of the power difference to the voltage difference; Determine the target disturbance step size according to the absolute value of the power difference; According to the disturbance direction and the target disturbance step size, the reference voltage of the maximum power point of the photovoltaic module is updated, so that the photovoltaic module operates according to the updated reference voltage. 2. The method of claim 1, wherein the determining a target disturbance step size according to the absolute value of the power difference comprises: Get the hysteresis interval identifier; Determine whether the absolute value of the power difference falls within the hysteresis interval corresponding to the hysteresis interval identifier, if so, do not update the hysteresis interval identifier; The hysteresis interval updates the hysteresis interval identifier; The disturbance step size corresponding to the hysteresis interval identifier is acquired, and the disturbance step size corresponding to the hysteresis interval identifier is used as the target disturbance step size. 3. The method according to claim 2, wherein the hysteresis interval comprises a first hysteresis interval and a second hysteresis interval, the first hysteresis interval is [0, a], and the first hysteresis interval is [0, a]. The second hysteresis interval is [a1,b], a1<a<b; the first hysteresis interval corresponds to the first disturbance step size, and the second hysteresis interval corresponds to the second disturbance step size; the first hysteresis interval corresponds to the second disturbance step size; The value of the hysteresis interval identifier of the hysteresis interval is X, the value of the hysteresis interval identifier of the second hysteresis interval is Y, and X<Y; The judging whether the absolute value of the power difference falls within the hysteresis interval corresponding to the hysteresis interval identifier, and if so, the hysteresis interval identifier is not updated, and if not, corresponding to the absolute value of the power difference. The hysteresis interval of updating the hysteresis interval identifier, including: Determine whether the absolute value of the power difference is less than or equal to a; If the absolute value of the power difference is less than or equal to a, determine whether the value of the hysteresis interval identifier is greater than or equal to Y; If the value of the hysteresis interval identifier is less than Y, determine that the absolute value of the power difference belongs to the first hysteresis interval, and update the value of the hysteresis interval identifier to X; If the value of the hysteresis interval identifier is greater than or equal to Y, determine whether the absolute value of the power difference is less than a1; If the absolute value of the power difference is less than a1, determine that the absolute value of the power difference belongs to the first hysteresis interval, and update the value of the hysteresis interval identifier to X; If the absolute value of the power difference is not less than a1, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value identified by the hysteresis interval is updated to Y. 4. The method according to claim 3, wherein the hysteresis interval further comprises a third hysteresis interval, and the third hysteresis interval is [b1, ∞], a<b1<b, the The third hysteresis interval corresponds to the third disturbance step size, and the value of the hysteresis interval identifier of the third hysteresis interval is Z, Y<Z, after judging whether the absolute value of the power difference is less than or equal to a, Also includes: If the absolute value of the power difference is greater than a, then determine whether the value of the hysteresis interval identifier is equal to X; If the value of the hysteresis interval identifier is equal to X, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the value of the hysteresis interval identifier is updated to Y; If the value of the hysteresis interval identifier is not equal to X, determine whether the value of the hysteresis interval identifier is equal to Y; If the value of the hysteresis interval identifier is equal to Y, it is determined whether the absolute value of the power difference is greater than b; if the absolute value of the power difference is greater than b, it is determined that the absolute value of the power difference belongs to the third hysteresis interval, update the value identified by the hysteresis interval to Z; if the absolute value of the power difference is not greater than b, it is determined that the absolute value of the power difference belongs to the second hysteresis interval, and the The value of the hysteresis interval identifier is updated to Y; If the value of the hysteresis interval identifier is not equal to Y, determine whether the absolute value of the power difference is greater than b1; if the absolute value of the power difference is not greater than b1, determine that the absolute value of the power difference belongs to the In the second hysteresis interval, the value of the hysteresis interval is updated to Y; if the absolute value of the power difference is greater than b1, it is determined that the absolute value of the power difference belongs to the third hysteresis interval, and the absolute value of the power difference is determined to belong to the third hysteresis interval. The value of the hysteresis interval identifier is updated to Z. 5 . The method of claim 1 , wherein the determining, according to the ratio of the power difference to the voltage difference, the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module comprises: 5 . If the ratio of the power difference to the voltage difference is greater than a preset ratio, determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module as the first disturbance direction; If the ratio of the power difference to the voltage difference is smaller than the preset ratio, determining the disturbance direction of the reference voltage of the maximum power point of the photovoltaic module as the second disturbance direction; The updating the reference voltage of the maximum power point of the photovoltaic module according to the disturbance direction and the target disturbance step size includes: If the disturbance direction is the first disturbance direction, increasing the reference voltage of the maximum power point by the target disturbance step size; If the disturbance direction is the second disturbance direction, the reference voltage of the maximum power point is reduced by the target disturbance step size. 6. The method according to any one of claims 1-5, wherein the sampling of the output voltage and output current of the photovoltaic module, before obtaining the first output voltage and the first output current at the current sampling time, further include: setting the reference voltage to be determined as the open circuit voltage of the photovoltaic module; The reference voltage to be determined is gradually reduced according to the preset disturbance step size, and the output voltage, output current and output power of the photovoltaic module are recorded, and the maximum output power among all the recorded output powers is obtained. The corresponding output voltage is used as the reference voltage of the maximum power point of the photovoltaic module. 7 . The method according to claim 6 , wherein the to-be-determined reference voltage is gradually reduced according to a preset disturbance step size, and the output voltage, output current and output power of the photovoltaic module are recorded to obtain the The maximum output power among all the recorded output powers, and the output voltage corresponding to the maximum output power as the reference voltage of the maximum power point of the photovoltaic module includes: reducing the to-be-determined reference voltage by a preset disturbance step size; judging whether the reduced reference voltage to be determined is less than a preset ratio of the open-circuit voltage, where the preset ratio is less than 1; If the reduced reference voltage to be determined is not less than the preset ratio of the open circuit voltage, sampling the output voltage and output current of the photovoltaic module, and calculating the output power; Judging whether the output power is greater than the historical maximum output power, the historical maximum output power is the maximum output power determined according to the sampled output voltage and output current in the process of gradually reducing the reference voltage to be determined; If the output power is greater than the historical maximum output power, update the historical maximum output power to the output power, use the reduced reference voltage to be determined as the reference voltage to be determined, and return to executing the step of reducing the reference voltage to be determined by a preset disturbance step size; if the output power is not greater than the historical output power, then returning to the step of reducing the to-be-determined reference voltage by a preset disturbance step size; If the reduced reference voltage to be determined is smaller than the preset ratio of the open circuit voltage, the output voltage corresponding to the historical maximum output power is used as the reference voltage of the maximum power point of the photovoltaic module. 8. The method of claim 1, further comprising: in response to a charging request operation, acquiring a request parameter of the charging request operation, the request parameter including a request voltage and a request current; acquiring output parameters of the photovoltaic module, and comparing the request parameters with the output parameters, where the output parameters include output voltage and output current; If the requested voltage is less than the output voltage, controlling the photovoltaic module to operate in a constant voltage output mode; If the requested voltage is greater than or equal to the output voltage, and the requested current is greater than or equal to the output current, controlling the photovoltaic module to operate in a maximum power point tracking mode; If the requested voltage is greater than or equal to the output voltage, and the requested current is less than the output current, the photovoltaic module is controlled to operate in a constant current output mode. 9. A photovoltaic controller comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer The program implements the method according to any one of claims 1 to 8. 10. A photovoltaic system, characterized in that the photovoltaic system comprises a photovoltaic component, a tracking device, a DC bus and a load, the photovoltaic component is connected to one end of the tracking device, and the other end of the tracking device is connected to the tracking device. One end of the DC bus is connected, and the other end of the DC bus is connected to the load, the tracking device includes a photovoltaic controller, and the photovoltaic controller is used to implement the method according to any one of claims 1 to 8 .

Images