WO2018170803A1

WO2018170803A1 - Photovoltaic power generation system, and method for controlling maximum power point tracking (mppt)

Info

Publication number: WO2018170803A1
Application number: PCT/CN2017/077761
Authority: WO
Inventors: 胡炎申
Original assignee: 胡炎申
Priority date: 2017-03-22
Filing date: 2017-03-22
Publication date: 2018-09-27
Also published as: CN108323219A

Abstract

A photovoltaic power generation system, and a method for controlling maximum power point tracking (MPPT). The system comprises: a photovoltaic module (102), for converting collected solar energy into a direct current; a smart junction box (104) connected to the photovoltaic module (102), for acquiring electricity data of the direct current converted by the photovoltaic module (102), the electricity data comprising at least one of voltage, current, power, and temperature; a cloud processor (106) connected to the smart junction box (104), for receiving the electricity data sent by the smart junction box (104), and calculating processing data of the photovoltaic module (102) according to the electricity data; and a photovoltaic inverter (108) connected to the cloud processor (106), for receiving the processing data sent by the cloud processor (106), and searching for a maximum power point according to the processing data and an MPPT algorithm. By adopting this technical solution, MPPT tracking speed and accuracy can be enhanced, and Liebeg's barrel effect and multi-peak phenomenon of a photovoltaic module string can also be improved, thereby increasing the power generation of a photovoltaic power generation system.

Description

Photovoltaic power generation system and maximum power point tracking MPPT control method

Technical field

The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation system and a control method for maximum power point tracking MPPT.

Background technique

In the photovoltaic power generation system, as shown in FIG. 1 , the photovoltaic component converts the solar light energy into direct current electricity, and the plurality of photovoltaic components are connected in series to form a photovoltaic string, and then the plurality of photovoltaic groups are connected in series and in parallel to form a photovoltaic array, and the photovoltaic module is passed through the string. Parallel to increase voltage, increase current, combiner box, power distribution cabinet, etc. to achieve electrical connection function, thereby obtaining higher voltage and power, and then realize grid-connected power generation through photovoltaic inverter. The photovoltaic module is shown in Figure 2. The junction box is mounted on the back and a bypass diode is integrated inside.

At the same time, the PV inverter has the function of maximum power point tracking (MPPT), detects the DC voltage and output current of the main circuit, calculates the output power of the PV array, and automatically searches for PV strings or PVs through internal software algorithms. The maximum power point of the array.

As shown in FIG. 3, when the current of one of the plurality of photovoltaic modules connected in series is reduced, the total current of the entire photovoltaic string is directly reduced, which is called the barrel effect. And when a component is reduced in current due to various reasons, and the current of other components is still normal, during the tracking of the MPPT, the maximum power point of the PV inverter may track the value of this current or the bypass diode is turned on. Loss of this component power causes multi-peak phenomena in the MPPT tracking process, as shown in Figure 4, resulting in a reduction in the actual output power of the entire PV string.

Summary of the invention

Based on this, in order to improve the wooden barrel effect brought by the series connection of multiple photovoltaic modules in the above-mentioned conventional technology and the multi-peak phenomenon occurring in the MPPT tracking process, the technical problem of reducing the actual output power of the entire photovoltaic string provides a photovoltaic power generation. system.

A first aspect of the invention provides a photovoltaic power generation system, the system comprising:

a photovoltaic module for converting light energy of the collected sun into direct current;

a smart junction box connected to the photovoltaic component, configured to acquire power quantity data of the direct current converted by the photovoltaic component, the power quantity data including at least one of voltage, current, power and temperature;

a cloud processor connected to the smart junction box, configured to receive power data sent by the smart junction box, and calculate processing data of the photovoltaic component according to the power data;

And a photovoltaic inverter connected to the cloud processor, configured to receive processing data sent by the cloud processor, and search for a maximum power point according to the processing data and an MPPT algorithm.

In a first possible implementation manner of the first aspect, the smart junction box further includes a microprogram controller, configured to control the microprogram controller when the obtained power quantity data of the photovoltaic component is normalized A switching unit coupled to the photovoltaic component to electrically disconnect the photovoltaic component.

In a second possible implementation manner of the first aspect, the processing data includes at least a quantity of the photovoltaic component, a voltage average value of the photovoltaic component, a current average value, and an output power;

The cloud processor is further configured to obtain an actual output power value of the photovoltaic component, and when the actual output power value is less than the output power, determine that the photovoltaic component has a wooden barrel effect;

A monitoring module coupled to the cloud processor for alerting the system to maintain the photovoltaic module having a barrel effect.

In a third possible implementation manner of the first aspect, the photovoltaic inverter is further configured to receive an initial value of an MPPT algorithm sent by the cloud processor, and set an initial value of the MPPT algorithm of the MPPT algorithm.

In a fourth possible implementation manner of the first aspect, the communication between the photovoltaic component and the cloud processor, and the photovoltaic inverter and the cloud processor is a wired connection and/or Wireless connections.

In addition, in order to improve the wooden barrel effect brought by the series connection of multiple photovoltaic modules in the above-mentioned conventional technology and the multi-peak phenomenon occurring in the MPPT tracking process, the technical problem of reducing the actual output power of the entire photovoltaic string provides a photovoltaic power generation system. The maximum power point is tracked by the MPPT control method.

A second aspect of the present invention provides a method for controlling a maximum power point tracking MPPT of a photovoltaic power generation system, the method comprising:

The photovoltaic component converts the collected light energy of the sun into direct current;

The smart junction box acquires electric quantity data of the direct current converted by the photovoltaic component, and the electric quantity data includes at least one of a voltage, a current, a power, and a temperature;

Receiving, by the cloud processor, the power data sent by the smart junction box, and calculating the processing data of the photovoltaic component according to the power data;

The photovoltaic inverter receives the processing data sent by the cloud processor, and searches for a maximum power point according to the processed data and the MPPT algorithm.

In a first possible implementation manner of the second aspect, the acquiring, by the smart junction box, the power data of the direct current converted by the photovoltaic component further includes:

When the power data of the photovoltaic module acquired by the microprogram controller is normal, the switch unit is controlled to turn off the electrical connection of the photovoltaic component.

In a second possible implementation manner of the second aspect, the processing data includes at least a quantity of the photovoltaic component, a voltage average value of the photovoltaic component, a current average value, and an output power;

The cloud processor receives the power data sent by the smart junction box, and the processing data of the photovoltaic component is calculated according to the power data.

In a third possible implementation manner of the second aspect, the receiving, by the photovoltaic inverter, the processing data sent by the cloud processor, and searching the maximum power point according to the processing data and the MPPT algorithm further includes:

Receiving an initial value of the MPPT algorithm sent by the cloud processor, and setting an initial value of the MPPT algorithm of the MPPT algorithm.

In a fourth possible implementation manner of the fourth aspect, the communication between the photovoltaic component and the cloud processor, and the photovoltaic inverter and the cloud processor is a wired connection and/or Wireless connections.

Implementation of the embodiments of the present invention will have the following beneficial effects:

After adopting the above-mentioned photovoltaic power generation system and the maximum power point tracking MPPT control method, the smart junction box obtains the electricity quantity data of the photovoltaic component, and uploads the power quantity data to the cloud processor, and the cloud processor calculates the processing of the photovoltaic component according to the power quantity data. The data is then sent to the photovoltaic inverter, which finds the maximum power point based on the processed data and the MPPT algorithm. According to the power data of the cloud processor processing the photovoltaic component, the photovoltaic component that causes the barrel effect is determined, and the search of the maximum power point is based on the processing data, so that the MPPT algorithm is quickly set to a certain peak in the multi-peak curve, and the MPPT tracking speed is improved. With the accuracy, the barrel effect and multi-peak phenomenon of the photovoltaic string are improved, thereby increasing the power generation of the photovoltaic power generation system.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

among them:

1 is a structural view of a device of a photovoltaic array;

2 is a structural view of a device of a photovoltaic module;

Figure 3 is a circuit diagram of the barrel effect caused by the series connection of photovoltaic modules;

Figure 4 is a circuit diagram of a multi-peak phenomenon caused by a series connection of photovoltaic modules;

FIG. 5 is a structural diagram of a device of a photovoltaic power generation system according to the present invention; FIG.

6 is a structural diagram of a device for a photovoltaic module and a smart junction box provided by the present invention;

FIG. 7 is a flowchart of a method for controlling a maximum power point tracking MPPT of a photovoltaic power generation system according to the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, instead of All embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

In order to improve the barrel effect brought by the series connection of multiple photovoltaic modules in the above conventional technology and the multi-peak phenomenon occurring in the MPPT tracking process, the technical problem of the actual output power of the entire photovoltaic string is reduced. A first aspect of the invention provides a photovoltaic power generation system. The photovoltaic power generation system can be applied to single-phase or three-phase alternating current systems according to circuit phase classification, and can be applied to photovoltaic grid-connected, photovoltaic off-grid or photovoltaic energy storage systems according to application type classification.

Specifically, as shown in FIG. 5, the photovoltaic power generation system includes a photovoltaic module 102, a smart junction box 104 connected to the photovoltaic module 102, a cloud processor 106 connected to the smart junction box 104, and the cloud processing The photovoltaic inverter 108 connected to the device 106, wherein:

The photovoltaic module 102 is configured to convert the collected light energy of the sun into direct current.

A solar cell can only produce a voltage of about 0.5 volts, which is much lower than the voltage required for actual use. In order to meet the needs of practical applications, it is necessary to connect the solar cells into the photovoltaic modules 102. Photovoltaic module 102 (also called solar panel) is the core part of photovoltaic power generation system and the most important part of photovoltaic power generation system. Its function is to convert solar energy into electrical energy.

As shown in FIG. 1 , the photovoltaic module 102 converts the solar energy of the sun into direct current, and the plurality of photovoltaic modules 102 are connected in series to form a photovoltaic string, and then the plurality of photovoltaic groups are connected in series to form a photovoltaic array, which is improved by series and parallel connection of the photovoltaic modules 102. Voltage, increased current, combiner box, power distribution cabinet, etc. realize electrical connection function, thereby obtaining higher voltage and power, and then realize grid-connected power generation through photovoltaic inverter 108.

In this embodiment, the intelligent junction box 104 is configured to acquire the power quantity data of the direct current converted by the photovoltaic component 102, and the power quantity data includes at least one of voltage, current, power, and temperature.

Similar to the photovoltaic module shown in FIG. 2, a junction box is mounted on the back of the photovoltaic module 102, however the junction box here is a smart junction box 104 for collecting one of voltage, current, power and temperature of the respective photovoltaic module 102 or A plurality of power data and a communication monitoring function, and the detected power data is sent to the cloud processor 106. In addition, the cloud processor 106 can also receive the relevant control commands to the PV module 102 through the smart junction box 104. Specifically, as shown in FIG. 6, the smart junction box 104 is internally included. Microprogram controller 1042 and switching unit 1044 coupled to microprogram controller 1042 and photovoltaic component 102.

When the microprogram controller 1042 detects that the power data of the photovoltaic module 102 is in a normal state (eg, fire, maintenance, etc.), the switch unit 1044 connected to the microprogram controller 1042 is controlled to turn off the electrical connection of the photovoltaic component 102. Switch unit 1046 can be a relay or other button or switching device for turning on the electrical connection of photovoltaic module 102. That is, the microprogram controller 1042 detects whether the power data of the photovoltaic module 102 acquired by the smart junction box 104 is at an abnormal value, and if so, turns off the electrical connection of the photovoltaic module 102 by controlling the switch unit 1044.

For example, when the microprogram controller 1042 detects that the current voltage is abnormal, it is determined that the voltage is shorted, and the microprogram controller 1042 notifies the switch unit 1044 to turn off the electrical connection of the photovoltaic module 102.

In this embodiment, the cloud processor 106 is configured to receive the power data sent by the smart junction box 104, and calculate the processing data of the photovoltaic component according to the power data.

The cloud processor 106 connected to the smart junction box 104 can be connected by wire or wirelessly, that is, the communication mode of the photovoltaic component 102 and the cloud processor 106 is wired or wireless. In addition, the communication mode adopted between the photovoltaic inverter 108 and the cloud processor 106 is a wired connection or a wireless connection.

The processing data includes at least the number of photovoltaic modules 102, the voltage average of the photovoltaic modules 102, the current average, and the output power, and may further include an average voltage and an average current of the photovoltaic strings that are connected in series by the photovoltaic modules 102, and the like.

Optionally, the cloud processor 106 is further configured to obtain an actual output power value of the photovoltaic component 102, and when the actual output power value is less than the output power, determine that the photovoltaic component 102 has a wooden barrel effect; A monitoring module coupled to the cloud processor 106 is configured to alert the system to maintain the photovoltaic module 102 having a barrel effect.

That is, the system can include a monitoring unit coupled to the cloud processor 106 that, when it is determined that there is a barrel effect of the photovoltaic module 102, informs the system to alert which particular photovoltaic module caused the resulting barrel effect.

As shown in FIG. 3, when the current of one of the plurality of photovoltaic modules connected in series is reduced, the total current of the entire photovoltaic string is directly reduced, which is called the barrel effect. By comparing photovoltaic groups The actual value of the output power of the device 102 and the size of the processed data. When the actual value of the output power is less than the processed data, the current of the photovoltaic module 102 is reduced, and the photovoltaic module 102 is judged to have a barrel effect, thereby reminding the system that the photovoltaic module needs to be maintained. In order to improve the cost and efficiency of photovoltaic system operation and maintenance. At the same time, the cloud processor 106 delivers the processing data to the photovoltaic inverter 108.

In this embodiment, the photovoltaic inverter 108 is configured to receive processing data sent by the cloud processor 106, and search for the maximum power point according to the processing data and the MPPT algorithm.

The photovoltaic module 102, the cloud processor 106, and the photovoltaic inverter 108 communicate with each other, and the working states of the photovoltaic module 102 and the photovoltaic inverter 108 can be reported to the cloud processor 106, and the cloud processor 106 issues the relevant control commands. For the photovoltaic module 102 and the photovoltaic inverter 108, the communication method can be either a wired connection or a wireless connection.

Maximum Power Point Tracking (MPPT) detects the DC voltage and output current of the main circuit, calculates the output power of the PV array, and automatically finds the maximum power point of the PV string or PV array through the internal software MPPT algorithm.

As shown in the multi-peak phenomenon shown in Figure 4, when a component is reduced in current due to various reasons, and the current of other components is still normal, during the tracking of the MPPT by the PV inverter, the maximum power point may track this current to be small. The value, or bypass diode conduction, loses power to this component, causing multi-peak phenomena in the MPPT tracking process, resulting in a reduction in the actual output power of the entire PV string.

After receiving the processing data sent by the cloud processor 106, the PV inverter 108 can set the initial value of the internal hardware and software circuit MPPT algorithm according to the MPPT algorithm initial value and the processing data to find the photovoltaic component that causes the multi-peak phenomenon. The MPPT algorithm is quickly set to a certain peak in the multimodal curve, thereby improving the multi-peak phenomenon of the photovoltaic module 102 and realizing a fast MPPT function. Then, according to finding the maximum power point, the photovoltaic module is adjusted to increase the power generation of the photovoltaic power generation system.

Optionally, the initial value of the MPPT algorithm sent by the cloud processor 106 is received, and the initial value of the MPPT algorithm of the MPPT algorithm is set. According to the initial value of the MPPT algorithm sent by the cloud processor 106, the MPPT tracking speed and accuracy are further accelerated, the multi-peak phenomenon of the photovoltaic component 102 is improved, and the fast MPPT function is realized. Specifically, the photovoltaic inverter is further configured to receive an initial value of an MPPT algorithm sent by the cloud processor, and set an initial value of the MPPT algorithm of the MPPT algorithm.

It should be noted that if the photovoltaic component 102 is disconnected from the electrical connection or the photovoltaic inverter 108 occurs When the machine is down, the above workflow ends.

In order to improve the barrel effect brought by the series connection of multiple photovoltaic modules in the conventional technology and the multi-peak phenomenon occurring in the MPPT tracking process, the technical problem of the actual output power reduction of the entire photovoltaic string is caused. A second aspect of the present invention provides a method for controlling a maximum power point tracking MPPT of a photovoltaic power generation system.

Specifically, as shown in FIG. 7, the maximum power point of the photovoltaic power generation system tracks the control method of the MPPT, including:

Step S102: The photovoltaic component converts the collected light energy of the sun into direct current.

Step S104: The smart junction box acquires the electric quantity data of the direct current converted by the photovoltaic component, and the electric quantity data includes at least one of a voltage, a current, a power and a temperature.

Step S106: The cloud processor receives the power quantity data sent by the smart junction box, and calculates the processing data of the photovoltaic component according to the power quantity data.

Step S108: The PV inverter receives the processing data sent by the cloud processor, and searches for the maximum power point according to the processing data and the MPPT algorithm.

In one embodiment, the smart junction box acquiring the power quantity data of the direct current converted by the photovoltaic component further comprises: when the power quantity data of the photovoltaic component acquired by the microprogram controller is normal, controlling the switch unit to turn off the The electrical connection of the photovoltaic module.

In one embodiment, the processing data includes at least the number of the photovoltaic components, a voltage average of the photovoltaic components, a current average, and an output power; the cloud processor receives the power sent by the smart junction box. Data, calculating the processing data of the photovoltaic component according to the power data, further comprising: the cloud processor is further configured to acquire an actual value of the output power of the photovoltaic component, where the actual value of the output power is less than the output power Determining that the photovoltaic module has a barrel effect; a monitoring module coupled to the cloud processor for alerting the system to maintain the photovoltaic module having a barrel effect.

In one embodiment, the photovoltaic inverter receives processing data sent by the cloud processor, and searching for the maximum power point according to the processing data and the MPPT algorithm further includes: receiving an MPPT sent by the cloud processor. The initial value of the algorithm sets an initial value of the MPPT algorithm of the MPPT algorithm.

In one embodiment, the photovoltaic component and the cloud processor, and the photovoltaic inverter The communication mode adopted between the cloud processor and the cloud processor is a wired connection and/or a wireless connection.

In summary, the implementation of the embodiments of the present invention will have the following beneficial effects:

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present invention are generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be from a website site, computer, server or data center Transfer to another website site, computer, server, or data center by wire (eg, coaxial cable, fiber optic, digital subscriber line (DSL), or wireless (eg, infrared, wireless, microwave, etc.). The computer readable storage medium can be any available media that can be accessed by a computer or a data storage device such as a server, data center, or the like that includes one or more available media. The usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (such as a solid state disk (SSD)) or the like.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and thus equivalent changes made in the claims of the present invention are still within the scope of the present invention.

Claims

A photovoltaic power generation system, comprising:

a photovoltaic module for converting light energy of the collected sun into direct current;

a smart junction box connected to the photovoltaic component, configured to acquire power quantity data of the direct current converted by the photovoltaic component, the power quantity data including at least one of voltage, current, power and temperature;

a cloud processor connected to the smart junction box, configured to receive power data sent by the smart junction box, and calculate processing data of the photovoltaic component according to the power data;

And a photovoltaic inverter connected to the cloud processor, configured to receive processing data sent by the cloud processor, and search for a maximum power point according to the processing data and an MPPT algorithm.
The system of claim 1 wherein said smart junction box further comprises:

And a microprogram controller, configured to control a switch unit connected to the microprogram controller and the photovoltaic component to turn off an electrical connection of the photovoltaic component when the obtained power quantity data of the photovoltaic component is normal.
The system of claim 1 wherein said processing data comprises at least said number of photovoltaic modules, a voltage average of said photovoltaic modules, a current average, and an output power;

The cloud processor is further configured to obtain an actual output power value of the photovoltaic component, and when the actual output power value is less than the output power, determine that the photovoltaic component has a wooden barrel effect;

A monitoring module coupled to the cloud processor for alerting the system to maintain the photovoltaic module having a barrel effect.
The system according to claim 1, wherein the photovoltaic inverter is further configured to receive an initial value of an MPPT algorithm sent by the cloud processor, and set an initial value of the MPPT algorithm of the MPPT algorithm.
The system according to claim 1, wherein the communication between the photovoltaic module and the cloud processor, and the photovoltaic inverter and the cloud processor is wired and/or wireless. connection.
A method for controlling a maximum power point tracking MPPT of a photovoltaic power generation system, characterized in that include:

The photovoltaic component converts the collected light energy of the sun into direct current;

The smart junction box acquires electric quantity data of the direct current converted by the photovoltaic component, and the electric quantity data includes at least one of a voltage, a current, a power, and a temperature;

Receiving, by the cloud processor, the power data sent by the smart junction box, and calculating the processing data of the photovoltaic component according to the power data;

The photovoltaic inverter receives the processing data sent by the cloud processor, and searches for a maximum power point according to the processed data and the MPPT algorithm.
The method according to claim 6, wherein the smart junction box obtains the power quantity data of the direct current converted by the photovoltaic component further comprises:

When the power data of the photovoltaic module acquired by the microprogram controller is normal, the switch unit is controlled to turn off the electrical connection of the photovoltaic component.
The method according to claim 6, wherein the processing data includes at least the number of the photovoltaic modules, a voltage average of the photovoltaic modules, a current average, and an output power;

The cloud processor receives the power data sent by the smart junction box, and the processing data of the photovoltaic component is calculated according to the power data.

Obtaining an actual output power value of the photovoltaic component, and determining that the photovoltaic module has a wooden barrel effect when the actual output power value is less than the output power;

A monitoring module coupled to the cloud processor for alerting the system to maintain the photovoltaic module having a barrel effect.
The method according to claim 6, wherein the receiving, by the photovoltaic inverter, the processing data sent by the cloud processor, and searching for the maximum power point according to the processing data and the MPPT algorithm further comprises:

Receiving an initial value of the MPPT algorithm sent by the cloud processor, and setting an initial value of the MPPT algorithm of the MPPT algorithm.
The method according to claim 6, wherein the communication between the photovoltaic component and the cloud processor, and the photovoltaic inverter and the cloud processor is wired and/or wireless connection.