Photovoltaic string series quantity adjustment control device, system and method

Abstract

The present application provides a photovoltaic string series quantity adjustment control device, system and method, belonging to the field of photovoltaic power generation technology, the method includes: a temperature monitoring unit monitors to obtain a temperature signal, a DC voltage acquisition unit acquires an output voltage signal of the photovoltaic string; a differential superposition unit obtains a first type of differential result, or obtains a second type of differential result while obtaining the first type of differential result, superimposes the first type of differential result with the second type of differential result, and obtains a superposition signal; a control unit generates a first control signal according to the first type of differential result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to turn on or off based on the first control signal or the second control signal; in the photovoltaic string, when each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings in series. The present application scheme can flexibly and accurately adjust the number of photovoltaic strings in series.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and specifically to a photovoltaic string series quantity adjustment control device, system and method. Background Art

[0002] The number of PV strings in series is determined by the lowest temperature under the working conditions of the PV strings. The lower the lowest daytime temperature in the PV field, the fewer the number of PV strings in series, the lower the output voltage of the PV strings, and the lower the power generation of the PV string series quantity regulation control system. When the lowest temperature of the day occurs, the PV strings are in standby mode, so the lowest temperature of the PV strings under working conditions is higher than the lowest temperature of the day.

[0003] Extreme low temperature weather accounts for a small proportion of the year, and areas with abundant sunlight resources have a large temperature difference between day and night. At the same time, due to seasonal changes, the time of sunrise and sunset will also change continuously, causing the time of the lowest temperature in a day to change with the seasons. Therefore, adjusting the number of photovoltaic strings in series according to the minimum temperature will cause the power generation of the photovoltaic string series number adjustment control system to decrease.

[0004] Therefore, how to flexibly and accurately adjust the number of photovoltaic strings in series has become a problem that needs to be solved. Summary of the invention

[0005] The purpose of the present application is to provide a photovoltaic string series quantity adjustment control device, which can solve the problem of how to flexibly and accurately adjust the series quantity of photovoltaic strings in the prior art.

[0006] In a first aspect, an embodiment of the present application provides a photovoltaic string series quantity adjustment control device, the device comprising: a difference superposition unit, a control unit, a temperature monitoring unit, a DC voltage acquisition unit and a switch unit; The first output end of the temperature monitoring unit is connected to the first input end of the control unit, the second output end of the temperature monitoring unit is connected to the first input end of the difference superposition unit, and the temperature monitoring unit is used to monitor the ambient temperature under the working conditions of the photovoltaic string to obtain a temperature signal; The input end of the DC voltage collection unit is connected to the DC output end of the photovoltaic string, the first output end of the DC voltage collection unit is connected to the second input end of the differential superposition unit, the second output end of the DC voltage collection unit is connected to the third input end of the differential superposition unit, and the DC voltage collection unit is used to collect the output voltage signal of the photovoltaic string; The fourth input end of the difference superposition unit is connected to the output end of the control system in the photovoltaic string series quantity regulation control system, and the output end of the difference superposition unit is connected to the second input end of the control unit. The difference superposition unit is used to perform a difference between the output voltage signal and the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, perform a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result, and superimpose the first type of difference result and the second type of difference result to obtain a superimposed signal; The output end of the control unit is connected to the control end of the switch unit, and the control unit is used to generate a first control signal according to the first type of difference result, or generate a second control signal according to the superposition signal, and control the corresponding switch unit to turn on or off based on the first control signal or the second control signal; In a photovoltaic string composed of N photovoltaic modules connected in series, a switch unit is provided at at least one location, each switch unit is connected in parallel to at least one photovoltaic module, and when each switch unit is in a conducting state, the photovoltaic module connected in parallel therewith is short-circuited to reduce the number of photovoltaic strings connected in series; The photovoltaic components connected in parallel with each switch unit are photovoltaic components for adjusting the number of strings.

[0007] In a possible implementation of the first aspect, the string quantity adjustment photovoltaic assembly includes: a first photovoltaic assembly to be adjusted, a second photovoltaic assembly to be adjusted, a third photovoltaic assembly to be adjusted, and a fourth photovoltaic assembly to be adjusted that are adjacent to each other; The photovoltaic components for adjusting the number of strings are the second part of the photovoltaic strings, and the remaining photovoltaic components are the first part of the photovoltaic strings. When the switch unit is in the off state, the photovoltaic components to be adjusted are connected to the first part of the photovoltaic strings.

[0008] In a possible implementation manner of the first aspect, the difference superposition unit includes: a first difference module, a minimum voltage calculation module, a second difference module and a result superposition module; The first input end of the first difference module is connected to the first output end of the DC voltage acquisition unit, the second input end of the first difference module is connected to the output end of the control system, the output end of the first difference module is connected to the first input end of the result superposition module, and the first difference module is used to perform a difference between the output voltage signal and the preset voltage signal to obtain a first type of difference result; The first input end of the minimum voltage calculation module is connected to the second output end of the temperature monitoring unit, the second input end of the minimum voltage calculation module is connected to the output end of the control system, the output end of the minimum voltage calculation module is connected to the first input end of the second difference module, and the minimum voltage calculation module is used to calculate the minimum output voltage according to the temperature signal, the preset voltage signal and the component equivalent open circuit voltage to obtain the minimum output voltage signal; The second input end of the second difference module is connected to the second output end of the DC voltage acquisition unit, the output end of the second difference module is connected to the second input end of the result superposition module, and the second difference module is used to perform a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result; The output end of the result superposition module is connected to the second input end of the control unit. The result superposition module is used to superimpose the first type of difference result and the second type of difference result to obtain a superposition signal.

[0009] In a possible implementation manner of the first aspect, the control unit includes: a main control module, a limit module, a signal superposition module and a PWM control module; The input end of the main control module is connected to the output end of the difference superposition unit, the output end of the main control module is connected to the first input end of the signal superposition module, and the main control module is used to generate a first type of main control signal based on the first type of difference result, or generate a second type of main control signal based on the superposition signal; The input end of the limit module is connected to the first input end of the temperature monitoring unit, the output end of the limit module is connected to the second input end of the signal superposition module, and the limit module is used to generate a first limit signal or a second limit signal based on the temperature signal; The output end of the signal superposition module is connected to the input end of the PWM control module, and the output end of the PWM control module is connected to the control end of each switch unit. The signal superposition module is used to perform a logical operation superposition on the temperature signal and the first type of main control signal according to the second limit signal to generate a first type of modulation signal, or to perform a logical operation superposition on the temperature signal and the second type of main control signal to generate a second type of modulation signal; The PWM control module is used to generate a first type of drive signal based on a first type of modulation signal, or to generate a second type of drive signal based on a second type of modulation signal, and to control each switch unit to turn on or off based on the first type of drive signal or the second type of drive signal.

[0010] In a possible implementation of the first aspect, the device includes: a first switch unit and a second switch unit; The control end of the first switch unit is connected to the first output end of the control unit, the first controlled end of the first switch unit is connected to the negative electrode of the first photovoltaic component to be adjusted, and the second controlled end of the first switch unit is connected to the positive electrode of the second photovoltaic component to be adjusted. The first switch unit is used to short-circuit the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted when it is in the on state, or connect the first photovoltaic component to be adjusted with the second photovoltaic component to be adjusted, and connect the third photovoltaic component to be adjusted with the fourth photovoltaic component to be adjusted when it is in the off state; The control end of the second switch unit is connected to the second output end of the control unit, the first controlled end of the second switch unit is connected to the negative electrode of the third photovoltaic component to be adjusted, and the second controlled end of the second switch unit is connected to the positive electrode of the fourth photovoltaic component to be adjusted. The second switch unit is used to short-circuit the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted when it is in the on state, or to connect the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted to the first part of the photovoltaic string at the same time when it is in the off state; Wherein, when the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted are short-circuited, the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted are simultaneously disconnected from the first part of the photovoltaic string.

[0011] In a possible implementation manner of the first aspect, the first switch unit includes: a first switch device and a first diode, and the second switch unit includes: a second switch device and a second diode; The control end of the first switch device is connected to the first output end of the control unit, the first controlled end of the first switch device is connected to the negative electrode of the first photovoltaic component to be adjusted, the second controlled end of the first switch device is connected to the anode of the first diode, the cathode of the first diode is connected to the positive electrode of the second photovoltaic component to be adjusted, and the first diode is used to prevent current from flowing from the positive electrode of the second photovoltaic component to be adjusted to the negative electrode of the first photovoltaic component to be adjusted; The control end of the second switching device is connected to the second output end of the control unit, the first controlled end of the second switching device is connected to the negative electrode of the third photovoltaic component to be regulated, the second controlled end of the second switching device is connected to the anode of the second diode, the cathode of the second diode is connected to the positive electrode of the fourth photovoltaic component to be regulated, and the second diode is used to prevent current from flowing from the positive electrode of the fourth photovoltaic component to be regulated to the negative electrode of the third photovoltaic component to be regulated.

[0012] In a possible implementation manner of the first aspect, the device further includes a signal input unit; The input end of the signal input unit is connected to the output end of the control system, and the output end of the signal input unit is connected to the fourth input end of the differential superposition unit. The signal input unit is used to input a preset voltage signal output by the control system and output a preset voltage signal to the differential superposition unit.

[0013] In a possible implementation manner of the first aspect, the device includes: a differential superposition unit, a control unit, a temperature monitoring unit, a DC voltage acquisition unit, and a plurality of switch units; wherein the DC voltage acquisition unit includes a plurality of input terminals and a plurality of first output terminals and a second output terminal, the differential superposition unit includes: a plurality of second input terminals and a third input terminal, the control unit includes a plurality of output terminals, and there are a plurality of photovoltaic strings connected to the input terminal of the DC voltage acquisition unit; The first output end of the temperature monitoring unit is connected to the first input end of the control unit, the second output end of the temperature monitoring unit is connected to the first input end of the difference superposition unit, and the temperature monitoring unit is used to monitor the ambient temperature under the working conditions of each photovoltaic string to obtain multiple temperature signals; Each input end of the DC voltage collection unit is connected to the DC output end of the corresponding photovoltaic string, each first output end of the DC voltage collection unit is connected to each second input end of the differential superposition unit, each second output end of the DC voltage collection unit is connected to each third input end of the differential superposition unit, and the DC voltage collection unit is used to collect the output voltage signal of each photovoltaic string; The fourth input terminal and the fifth input terminal of the difference superposition unit are connected to the output terminal of the external control system, and the output terminal of the difference superposition unit is connected to the second input terminal of the control unit. The difference superposition unit is used to perform difference between the output voltage signal of each photovoltaic string and the preset voltage signal to obtain multiple first-type difference results, or while obtaining the first-type difference results, perform difference between each output voltage signal and the lowest output voltage signal to obtain multiple second-type difference results, and superimpose each first-type difference result with each second-type difference result to obtain multiple superposition signals; The output end of the control unit is connected to the control end of the switch unit, and the control unit is used to generate a corresponding first control signal according to each first-type difference result, or generate a corresponding second control signal according to each superposition signal, and control the corresponding switch unit to be turned on or off according to the first control signal and the second control signal; In each photovoltaic string composed of N photovoltaic modules connected in series, a switch unit is provided at least at one location, each switch unit is connected in parallel to at least one photovoltaic module, and when each switch unit is in the on state, the photovoltaic module connected in parallel therewith is short-circuited to reduce the number of series connections of the corresponding photovoltaic strings; wherein the photovoltaic modules connected in parallel to each switch unit are adjusted for the corresponding number of strings.

[0014] In a second aspect, an embodiment of the present application provides a photovoltaic string series quantity adjustment control system, the system comprising: a photovoltaic string, an inverter, a box-type transformer AC device, a control system, and a photovoltaic string series quantity adjustment control device; The DC input end of the photovoltaic string is connected to the output end of the photovoltaic string series quantity adjustment control device, and the DC output end of the photovoltaic string is connected to the power supply input end of the inverter and the first input end of the photovoltaic string series quantity adjustment control device. The photovoltaic string is used to provide an output voltage signal to the photovoltaic string series quantity adjustment control device and output direct current after adjusting the number of photovoltaic strings in series to the inverter; The output end of the inverter is connected to the input end of the box-type transformer AC device. The inverter is used to invert the DC power output by the photovoltaic string into AC power and output the AC power to the box-type transformer AC device. The output end of the box-type transformer AC device is connected to the input end of the power grid. The box-type transformer AC device is used to collect and boost the AC power output by the inverter, and output the boosted AC power to the power grid; The output end of the control system is connected to the second input end of the photovoltaic string series quantity adjustment control device, and the control system is used to output a preset voltage signal to the photovoltaic string series quantity adjustment control device; The photovoltaic string series quantity adjustment control device is used to adjust the series quantity of the photovoltaic strings based on the ambient temperature signal under the working conditions of the photovoltaic strings, the output voltage signal provided by the photovoltaic strings and the preset voltage signal.

[0015] In a possible implementation of the second aspect, the system includes: a plurality of photovoltaic strings, an inverter, a box-type transformer AC device, a control system, and a photovoltaic string series quantity adjustment control device; wherein the photovoltaic string series quantity adjustment control device includes a plurality of first input terminals, a second input terminal, and a plurality of output terminals, and the inverter includes a plurality of power supply input terminals; The DC input end of each photovoltaic string is connected to the output end corresponding to the photovoltaic string series quantity adjustment control device, and the DC output end of each photovoltaic string is connected to the power supply input end corresponding to the inverter and the first input end corresponding to the photovoltaic string series quantity adjustment control device. Each photovoltaic string is used to provide the corresponding output voltage to the photovoltaic string series quantity adjustment control device and output the corresponding DC power after adjusting the photovoltaic string series quantity to the inverter; The output end of the inverter is connected to the input end of the box-type transformer AC device. The inverter is used to invert the DC power output by each photovoltaic string into AC power and output the AC power to the box-type transformer AC device. The output end of the box-type transformer AC device is connected to the input end of the power grid. The box-type transformer AC device is used to collect and boost the AC power output by the inverter, and output the boosted AC power to the power grid; The output end of the control system is connected to the second input end of the photovoltaic string series quantity adjustment control device, and the control system is used to output a preset voltage signal to the photovoltaic string series quantity adjustment control device; The photovoltaic string series quantity adjustment control device is used to adjust the series quantity of each photovoltaic string based on the ambient temperature signal under the working conditions of each photovoltaic string, the output voltage signal provided by each photovoltaic string and the preset voltage signal.

[0016] In a third aspect, an embodiment of the present application provides a method for adjusting and controlling the number of photovoltaic strings connected in series, which is implemented based on the photovoltaic string number adjustment and control device in any one of the first aspects, and the method includes: Based on the temperature monitoring unit, the ambient temperature under the working condition of the photovoltaic string is monitored to obtain a temperature signal; The output voltage signal of the photovoltaic string is collected based on the DC voltage collection unit; Based on the difference superposition unit, the output voltage signal is subtracted from the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal is subtracted from the minimum output voltage signal to obtain a second type of difference result, and the first type of difference result and the second type of difference result are superimposed to obtain a superimposed signal; Based on the control unit, a first control signal is generated according to the first type of difference result, or a second control signal is generated according to the superposition signal, and a corresponding switch unit is controlled to be turned on or off based on the first control signal or the second control signal; When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings connected in series; wherein the photovoltaic components connected in parallel with each switch unit are photovoltaic components for adjusting the number of strings.

[0017] In a possible implementation of the third aspect, the difference superposition unit includes: a first difference module, a minimum voltage calculation module, a second difference module and a result superposition module; the control unit includes: a main control module, a limit module, a signal superposition module and a PWM control module, and the device includes: a first switch unit and a second switch unit; the string quantity adjustment photovoltaic assembly includes: adjacent first photovoltaic assemblies to be adjusted, second photovoltaic assemblies to be adjusted, third photovoltaic assemblies to be adjusted and fourth photovoltaic assemblies to be adjusted, the string quantity adjustment photovoltaic assembly is the second part of the photovoltaic string, and the remaining photovoltaic assemblies are the first part of the photovoltaic string, and when each switch unit is in an off state, the string quantity adjustment photovoltaic assembly is connected to the first part of the photovoltaic string; the device also includes a signal input unit; based on the difference superposition unit, the output voltage signal and the preset voltage signal output by the control system are subtracted to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal and the minimum output voltage signal are subtracted to obtain a second type of difference result, and the first type of difference result is superimposed with the second type of difference result to obtain a superposition signal, including: When the first ambient temperature is lower than the standard test temperature: Subtracting the first output voltage signal from the preset voltage signal input by the signal input unit based on the first subtraction module to obtain a first subtraction result; When the second ambient temperature is lower than the first ambient temperature: Based on the first difference module, the second output voltage signal and the preset voltage signal are subtracted to obtain a second difference result, and at the same time, the first minimum output voltage is calculated based on the minimum voltage calculation module, and the second output voltage signal and the first minimum output voltage signal are subtracted based on the second difference module to obtain a third difference result, and the second difference result and the third difference result are superimposed based on the result superposition module to obtain a first superposition signal; When the third ambient temperature is lower than the second ambient temperature: Subtracting the third output voltage signal from the preset voltage signal based on the first subtraction module to obtain a fourth subtraction result; When the fourth ambient temperature is lower than the third ambient temperature: Based on the difference superposition unit, while obtaining the fifth difference result, the fourth output voltage signal and the second lowest output voltage signal are subtracted to obtain a sixth difference result, and based on the result superposition module, the fifth difference result and the sixth difference result are superimposed to obtain a second superposition signal; Among them, the first type of difference results include: the first difference result, the second difference result, the fourth difference result and the fifth difference result, and the second type of difference results include: the third difference result and the sixth difference result.

[0018] In a possible implementation manner of the third aspect, the output voltage signal is subtracted from a preset voltage signal output by the control system based on a subtraction and superposition unit to obtain a first type of subtraction result, or while obtaining the first type of subtraction result, the output voltage signal is subtracted from a minimum output voltage signal to obtain a second type of subtraction result, and the first type of subtraction result and the second type of subtraction result are superimposed to obtain a superimposed signal, further comprising: When the fifth ambient temperature is greater than the fourth ambient temperature: Based on the difference superposition unit, while obtaining the seventh difference result, the fifth output voltage signal and the third lowest output voltage signal are subtracted to obtain an eighth difference result, and based on the result superposition module, the seventh difference result and the eighth difference result are superimposed to obtain a third superposition signal; When the sixth ambient temperature is greater than the fifth ambient temperature: Based on the difference superposition unit, while obtaining the ninth difference result, the sixth output voltage signal and the fourth lowest output voltage signal are subtracted to obtain a tenth difference result, and based on the result superposition module, the ninth difference result and the tenth difference result are superimposed to obtain a fourth superposition signal; When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature: Based on the difference superposition unit, while obtaining the eleventh difference result, the seventh output voltage signal and the fifth lowest output voltage signal are subtracted to obtain a twelfth difference result, and based on the result superposition module, the eleventh difference result and the twelfth difference result are superimposed to obtain a fifth superposition signal; When the eighth ambient temperature is greater than the standard test temperature: Based on the difference superposition unit, while obtaining the thirteenth difference result, the eighth output voltage signal and the sixth lowest output voltage signal are subtracted to obtain a fourteenth difference result, and based on the result superposition module, the thirteenth difference result and the fourteenth difference result are superimposed to obtain a sixth superposition signal; Among them, the first category of difference results also includes: the seventh difference result, the ninth difference result, the eleventh difference result and the thirteenth difference result, and the second category of difference results also includes: the eighth difference result, the tenth difference result, the twelfth difference result and the fourteenth difference result.

[0019] In a possible implementation manner of the third aspect, the device includes: a first switch unit and a second switch unit; a control unit generates a first control signal according to a first type of difference result, or generates a second control signal according to a superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal, and when each switch unit is in an on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings in series, and when each switch unit is in an off state, the photovoltaic components for adjusting the number of strings are connected to the first part of the photovoltaic string, including: When the first ambient temperature is lower than the standard test temperature: Based on the main control module, a first main control signal is generated according to the first difference result; based on the limit module, a second limit signal is generated according to the first temperature signal; based on the signal superposition module, the first temperature signal is logically superimposed on the first main control signal according to the second limit signal to generate a first modulation signal; based on the PWM control module, a first drive signal is generated according to the first modulation signal; and according to the first drive signal, the first switch unit is controlled to be turned on to short-circuit the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted, and at the same time, the second switch unit is driven to be turned off according to the first drive signal to connect the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted to the first part of the photovoltaic string at the same time; When the second ambient temperature is lower than the first ambient temperature: Based on the control unit, a second driving signal is generated according to the first superimposed signal, and the first switch unit is controlled to be turned on according to the second driving signal, and the second switch unit is driven to be turned off according to the second driving signal; When the third ambient temperature is lower than the second ambient temperature: The control unit generates a third driving signal according to the fourth difference result, controls the first switch unit to be turned off according to the third driving signal, and controls the second switch unit to be turned on according to the third driving signal, so as to short-circuit the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted; When the fourth ambient temperature is lower than the third ambient temperature: Based on the control unit, a fourth drive signal is generated according to the second superimposed signal, and the first switch unit is controlled to be turned off according to the fourth drive signal, and the second switch unit is controlled to be turned on according to the fourth drive signal; The first type of main control signal includes a first main control signal.

[0020] In a possible implementation manner of the third aspect, the control unit generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal. When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings in series. When each switch unit is in the off state, the photovoltaic components for adjusting the number of strings are connected to the first part of the photovoltaic strings, and further includes: When the fifth ambient temperature is greater than the fourth ambient temperature: Based on the control unit, a fifth driving signal is generated according to the third superimposed signal, and the first switch unit is controlled to be turned on according to the fifth driving signal, and the second switch unit is driven to be turned off according to the fifth driving signal; When the sixth ambient temperature is greater than the fifth ambient temperature: Based on the control unit, a sixth driving signal is generated according to the fourth superimposed signal, and the first switch unit is controlled to be turned on according to the sixth driving signal, and the second switch unit is driven to be turned off according to the sixth driving signal; When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature: Based on the control unit, a seventh driving signal is generated according to the fifth superimposed signal, and the first switch unit and the second switch unit are controlled to be turned off according to the seventh driving signal; When the eighth ambient temperature is greater than the standard test temperature: The control unit generates an eighth driving signal according to the sixth superimposed signal, and controls the first switching unit and the second switching unit to be turned off according to the eighth driving signal.

[0021] In a possible implementation manner of the third aspect, the method includes: Based on the temperature monitoring unit, the ambient temperature of each photovoltaic string under the working condition is monitored to obtain multiple temperature signals; The output voltage signal of each photovoltaic string is collected based on the DC voltage collection unit; Based on the difference superposition unit, the output voltage signal of each photovoltaic string is subtracted from the preset voltage signal to obtain a plurality of first-type difference results, or while obtaining the first-type difference results, each output voltage signal is subtracted from the minimum output voltage signal to obtain a plurality of second-type difference results, and each first-type difference result is superimposed with each second-type difference result to obtain a plurality of superimposed signals; Based on the control unit, a corresponding first control signal is generated according to each first-type difference result, or a corresponding second control signal is generated according to each superposition signal, and the corresponding switch unit is controlled to be turned on or off according to the first control signal and the second control signal; When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of series connections of the corresponding photovoltaic strings; wherein the photovoltaic components connected in parallel with each switch unit are adjusted for the corresponding number of strings.

[0022] In the present application, the temperature monitoring unit monitors the ambient temperature under the working conditions of the photovoltaic string to obtain a temperature signal, and the DC voltage acquisition unit acquires the output voltage signal of the photovoltaic string; the difference superposition unit performs a difference between the output voltage signal and the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, performs a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result, and superimposes the first type of difference result with the second type of difference result to obtain a superposition signal; the control unit generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal; in a photovoltaic string composed of N photovoltaic components connected in positive and negative series, a switch unit is provided at least at one place, each switch unit is connected in parallel to at least one photovoltaic component, and when each switch unit is in the on state, the photovoltaic component connected in parallel therewith is short-circuited to reduce the number of photovoltaic strings connected in series.

[0023] The present application scheme sets a switch unit at at least one point in the photovoltaic string, and can use the switch unit to automatically, flexibly and accurately adjust the number of photovoltaic strings in series under different ambient temperatures. It is not limited by the minimum temperature under the working conditions of the photovoltaic strings, and has strong ease of use and practicality.

[0024] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 is a schematic block diagram of a photovoltaic string series quantity adjustment control device provided in an embodiment of the present application; Figure 2It is a schematic block diagram of the specific structure of a photovoltaic string series quantity adjustment control device provided in an embodiment of the present application; Figure 3 It is a schematic block diagram of the specific structure of a photovoltaic string series quantity adjustment control device provided in an embodiment of the present application; Figure 4 It is a schematic block diagram of the overall structure of a photovoltaic string series quantity adjustment control device for multiple photovoltaic strings provided in an embodiment of the present application; Figure 5 is a schematic block diagram of a photovoltaic string series quantity regulation control system including one photovoltaic string provided in an embodiment of the present application; Figure 6 is a schematic block diagram of a photovoltaic string series quantity regulation control system including a plurality of photovoltaic strings provided in an embodiment of the present application; Figure 7 It is a schematic diagram of the process of automatic adjustment control of the number of photovoltaic strings connected in series provided in an embodiment of the present application; Figure 8 This is a schematic diagram of the temperature variation over time provided in the embodiment of the present application; Fig. 9 is a waveform diagram of a PWM control signal provided in an embodiment of the present application; Fig.10 It is a schematic diagram of the steps of a method for adjusting the number of photovoltaic strings connected in series of a photovoltaic string provided in an embodiment of the present application; Fig.11 It is a schematic diagram of the steps of a method for adjusting and controlling the number of photovoltaic strings connected in series of multiple photovoltaic strings provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0028] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0029] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0030] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0031] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0032] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0033] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0034] In the present application specification, unless otherwise specified, directional words such as "up, down, left, right" generally refer to the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the invented product is usually placed when in use.

[0035] In the present application specification, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] With the rapid development of the current economy, the global demand for energy is increasing day by day, but the problems of fossil energy shortage and environmental pollution are gradually becoming prominent. Therefore, it is urgent to find new energy forms to replace fossil energy, which will become an important means to solve the problems of energy shortage and environmental pollution. Therefore, the use of clean, safe and pollution-free renewable energy has received more and more attention. New energy sources such as wind energy, solar energy, biomass energy, and ocean energy are constantly improving their status in the energy strategies of various countries due to their clean, safe and renewable characteristics. Among them, solar energy has relatively low cost, mature technology and high reliability. It has developed rapidly in recent years and has begun to play an important role in energy supply.

[0037] The most important form of solar energy utilization is photovoltaic power generation. For large ground-mounted photovoltaic power stations, the number of photovoltaic strings in series is mainly affected by the open circuit voltage Voc of the photovoltaic string, the open circuit voltage temperature coefficient Kv of the photovoltaic string, the maximum DC input voltage Vdcmax allowed by the inverter, and the ambient temperature T. In general design, the open circuit voltage Voc of the photovoltaic string, the open circuit voltage temperature coefficient Kv of the photovoltaic string, and the maximum DC input voltage Vdcmax allowed by the inverter can be determined according to the manufacturer's information and are fixed values, while the ambient temperature T is a variable that changes at any time, so it has become an important parameter affecting the number of photovoltaic strings in series.

[0038] The number of PV strings in series refers to the number of PV modules in series in each PV string, N, which can be calculated according to the following formula: (Formula 1); (Formula 2) Wherein, Kv represents the open circuit voltage temperature coefficient of the PV string, Kv´ represents the operating voltage temperature coefficient of the PV string, N represents the number of PV modules in series (N is an integer), T´ represents the minimum temperature of the PV string under working conditions, T´´ represents the maximum temperature of the PV string under working conditions, Vdcmax represents the maximum DC input voltage allowed by the inverter, Vmpptmax represents the maximum value of the inverter MPPT (Maximum Power Point Tracking) voltage, Voc represents the open circuit voltage of the PV string, and Vpm represents the operating voltage of the PV string (i.e., the output voltage of the PV string or the series voltage of the PV modules).

[0039] In order to achieve technical and economic optimization, ground photovoltaic power stations are generally designed with the maximum number of photovoltaic strings in series. In this case, it is only necessary to calculate according to Formula 1. Distributed photovoltaic string series quantity regulation control systems combined with buildings usually do not use the maximum number of photovoltaic strings in series design. In this case, it is necessary to combine Formula 1 and Formula 2 for comprehensive consideration to derive the range of the number of photovoltaic strings in series.

[0040] It can be seen from Formula 1 that when the open circuit voltage Voc of the photovoltaic string, the open circuit voltage temperature coefficient Kv of the photovoltaic string and the maximum DC input voltage Vdcmax allowed by the inverter are fixed, the number of photovoltaic strings in series N is proportional to the ambient temperature T. Assuming that the system voltage is 1500V, that is, the maximum DC input voltage Vdcmax allowed by the inverter is 1500V, and taking the parameters of a certain brand of photovoltaic modules as a reference, under standard test conditions, the open circuit voltage Voc of the photovoltaic string is 50V, the open circuit voltage temperature coefficient Kv of the photovoltaic string is -0.0026 / ℃, and the ambient temperature T under the working conditions of the photovoltaic string is 25℃, and the number of photovoltaic strings in series N is calculated to be 30 by substituting it into Formula 1. Table 1 is a table of the number of photovoltaic strings in series N at different ambient temperatures, and the number of photovoltaic strings in series N at different ambient temperatures is shown in Table 1.

[0041] From Table 1 and the characteristics of the photovoltaic modules, it can be seen that the voltage of the photovoltaic modules will decrease with the increase of the ambient temperature under the sunlight. Affected by the open-circuit voltage temperature coefficient, the open-circuit voltage of the photovoltaic string will decrease with the increase of the ambient temperature under the working conditions of the photovoltaic string. Therefore, as the ambient temperature of the photovoltaic string decreases, its open-circuit voltage will increase. In order to ensure that the inverter can work normally and continuously at the local minimum temperature, when calculating the working voltage of the photovoltaic string using the above formula, the influence of the local minimum temperature on the open-circuit voltage of the photovoltaic string should be considered. Therefore, the ambient temperature T should be the lowest temperature under the working conditions of the photovoltaic string.

[0042] Table 1 Serial number T Voc Kv Equivalent open circuit voltage Voc´ of PV string Vdcmax N N round up 1 45 50 -0.0026 47.4 1500 31.65 30 2 40 50 -0.0026 48.05 1500 31.22 30 3 35 50 -0.0026 48.7 1500 30.80 30 4 30 50 -0.0026 49.35 1500 30.40 30 5 25 50 -0.0026 50 1500 30.00 30 6 20 50 -0.0026 50.65 1500 29.62 28 7 15 50 -0.0026 51.3 1500 29.24 28 8 10 50 -0.0026 51.95 1500 28.87 28 9 5 50 -0.0026 52.6 1500 28.52 28 10 0 50 -0.0026 53.25 1500 28.17 28 11 -5 50 -0.0026 53.9 1500 27.83 26 12 -10 50 -0.0026 54.55 1500 27.50 26 13 -15 50 -0.0026 55.2 1500 27.17 26 14 -20 50 -0.0026 55.85 1500 26.86 26 15 -25 50 -0.0026 56.5 1500 26.55 26 16 -30 50 -0.0026 57.15 1500 26.25 26 It can be seen that the number of PV strings in series is determined by the lowest temperature under the working conditions of the PV strings. The lower the daytime lowest temperature in the PV field, the fewer the number of PV strings in series, the lower the output voltage of the PV strings, and the lower the power generation of the PV string series quantity regulation control system. When the lowest temperature of the day occurs, the PV strings are in standby mode, so the lowest temperature under the working conditions of the PV strings is higher than the lowest temperature of the day.

[0043] Extreme low temperature weather accounts for a small proportion of the year, and areas with abundant sunlight resources have a large temperature difference between day and night. At the same time, due to seasonal changes, the time of sunrise and sunset will also change continuously, causing the time of the lowest temperature in a day to change with the seasons. Therefore, adjusting the number of photovoltaic strings in series according to the minimum temperature will cause the power generation of the photovoltaic string series number adjustment control system to decrease.

[0044] The output voltage of the photovoltaic string (i.e., the input voltage of the inverter) cannot exceed the maximum DC input voltage allowed by the inverter. Limiting the output voltage of the photovoltaic string is generally achieved through the inverter. At present, there are not many solutions for adjusting the number of photovoltaic strings in series. In order to increase the number of photovoltaic strings in series, a voltage switch is set at the input end of the inverter in the prior art. When the output voltage of the photovoltaic string exceeds the maximum DC input voltage allowed by the inverter, the inverter will stop working. This usually causes the inverter to be unable to work at the rated state for a long time and fail to achieve the ideal efficiency. Therefore, how to flexibly and accurately adjust the number of photovoltaic strings in series has become a problem to be solved.

[0045] In view of the above-mentioned defects, the present application provides a photovoltaic string series quantity adjustment control device, wherein the temperature monitoring unit monitors the ambient temperature under the working conditions of the photovoltaic string to obtain a temperature signal, and the DC voltage acquisition unit acquires the output voltage signal of the photovoltaic string; the difference superposition unit performs a difference between the output voltage signal and the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, performs a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result, and superimposes the first type of difference result with the second type of difference result to obtain a superposition signal; the control unit generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal; in a photovoltaic string composed of N photovoltaic components connected in positive and negative series, a switch unit is provided at least at one place, each switch unit is connected in parallel to at least one photovoltaic component, and when each switch unit is in the on state, the photovoltaic component connected in parallel therewith is short-circuited to reduce the number of photovoltaic strings connected in series.

[0046] The present application scheme sets a switch unit at at least one point in the photovoltaic string, and can use the switch unit to automatically, flexibly and accurately adjust the number of photovoltaic strings in series under different ambient temperatures. It is not limited by the minimum temperature under the working conditions of the photovoltaic strings and has strong ease of use and practicality.

[0047] The overall structure of the photovoltaic string series quantity adjustment control device provided in the embodiment of the present application is introduced below through specific embodiments.

[0048] See also Figure 1 , Figure 1 1 is a schematic block diagram of a photovoltaic string series quantity adjustment control device 100 provided in an embodiment of the present application. Figure 1 As shown, the photovoltaic string series quantity adjustment control device 100 includes: a difference superposition unit 150, a control unit 110, a temperature monitoring unit 120, a DC voltage acquisition unit 130, a first switch unit 142 and a second switch unit 144.

[0049] The first output end of the temperature monitoring unit 120 is connected to the first input end of the control unit 110, and the second output end of the temperature monitoring unit 120 is connected to the first input end of the difference superposition unit 150. The temperature monitoring unit 120 is used to obtain an ambient temperature signal T by real-time monitoring the ambient temperature under the working conditions of the photovoltaic string 210 (i.e., the ambient temperature of the photovoltaic field area), and output the ambient temperature signal T to the control unit 110.

[0050] The input end of the DC voltage collection unit 130 is connected to the DC output end (including the positive and negative terminals BUS+ and BUS-) of the photovoltaic string 210, the first output end of the DC voltage collection unit 130 is connected to the second input end of the differential superposition unit 150, and the second output end of the DC voltage collection unit 130 is connected to the third input end of the differential superposition unit 150. The DC voltage collection unit 130 is used to collect the output voltage signal Vdc of the photovoltaic string 210 and provide the output voltage signal Vdc to the control unit 110.

[0051] The fourth input terminal of the difference superposition unit 150 is connected to the output terminal of the control system 230 in the photovoltaic string series quantity adjustment control system 200, and the output terminal of the difference superposition unit 150 is connected to the second input terminal of the control unit 110. The difference superposition unit 150 is used to perform a difference between the output voltage signal and the preset voltage signal output by the control system 230 to obtain a first type of difference result, or while obtaining the first type of difference result, perform a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result, and superimpose the first type of difference result and the second type of difference result to obtain a superimposed signal.

[0052] The preset voltage is the maximum DC input voltage Vdcmax allowed by the inverter.

[0053] The output end of the control unit 110 is connected to the control end of the switch unit. The control unit 110 is used to generate a first control signal according to the first type of difference result, or generate a second control signal according to the superposition signal, and control the corresponding switch unit to turn on or off based on the first control signal or the second control signal.

[0054] In some embodiments, the control unit 110 includes at least one output terminal. In a photovoltaic string consisting of N photovoltaic modules connected in series, a switch unit is provided at least at one location. Each switch unit is connected in parallel to at least one photovoltaic module, and a control terminal of each switch unit is connected to a corresponding output terminal of the control unit 110. When each switch unit is in a conducting state, the photovoltaic module connected in parallel therewith is short-circuited to reduce the number of photovoltaic strings connected in series. The photovoltaic modules connected in parallel to each switch unit adjust the photovoltaic modules for the corresponding number of strings.

[0055] It should be noted that, as can be seen from Table 1, the maximum number of photovoltaic strings connected in series is 30 and the minimum is 26. Therefore, N can be set to 30, and there can be 4 photovoltaic modules to be adjusted. N and the number of photovoltaic modules to be adjusted can be determined according to the specific circumstances in the actual application scenario, and are not specifically limited here. The present application scheme is introduced with N being 30 and 4 photovoltaic modules to be adjusted.

[0056] In one embodiment, in a photovoltaic string consisting of 30 photovoltaic components connected in series, a first switch unit 142 can be set at photovoltaic components A1 and A2, and the first switch unit 142 is connected in parallel to photovoltaic components A1 and A2; a second switch unit 144 can also be set at photovoltaic components B1 and B2, and the switch unit 144 is connected in parallel to photovoltaic components B1 and B2, and the control ends of the first switch unit 142 and the second switch unit 144 are respectively connected to the output end of the control unit 110.

[0057] When the first switch unit 142 and the second switch unit 144 are in the on state, the photovoltaic components A1, A2, B1 and B2 are short-circuited to reduce the number of photovoltaic strings 210 in series. When the photovoltaic components A1, A2, B1 and B2 are short-circuited, a part of the photovoltaic components is missing from the photovoltaic string 210, so that the number of photovoltaic strings 210 in series is reduced. Among them, the photovoltaic components A1, A2, B1 and B2 are the photovoltaic components 214 for adjusting the number of strings.

[0058] In one embodiment, the first output terminal and the second output terminal of the control unit 110 are respectively connected to the control terminals of the first switch unit 142 and the second switch unit 144. The control unit 110 is used to generate a first control signal UK1 or UK2 according to the first type of difference result, or generate a second control signal UK1 or UK2 according to the superposition signal, and control the corresponding switch unit to turn on or off based on the first control signal or the second control signal.

[0059] In another embodiment, in a photovoltaic string consisting of 30 photovoltaic modules connected in series, a switch unit may be provided at each of the photovoltaic modules A1, A2, B1, and B2. Four switch units are connected in parallel to the photovoltaic modules A1, A2, B1, and B2, respectively, and the control ends of the four switch units are connected to the output ends of the control unit 110, respectively. When the four switch units are in the on state, the photovoltaic modules A1, A2, B1, and B2 are short-circuited, respectively, to reduce the number of photovoltaic modules connected in series.

[0060] In another embodiment, a switch unit is provided at one location in a photovoltaic string consisting of 30 photovoltaic modules connected in series, and the switch unit is connected in parallel to four photovoltaic modules A1, A2, B1 and B2, and the control end of the switch unit is connected to the output end of the control unit 110.

[0061] In the solution of this embodiment, a switch unit is set at at least one point of the photovoltaic string 210, and the switch unit can be used to automatically and flexibly adjust the number of photovoltaic strings 210 in series at different ambient temperatures, without being restricted by the lowest temperature under the working conditions of the photovoltaic string 210. Under the premise of meeting the maximum DC input voltage allowed by the inverter, the maximum number of series connections can be guaranteed, the number of inverters and photovoltaic brackets is reduced, and the floor space of the photovoltaic field is also reduced, so that the investment in the photovoltaic project is reduced. In addition, the power generation of the photovoltaic string series quantity adjustment control system is increased, the economic performance of the photovoltaic project is improved, and it has strong ease of use and practicality.

[0062] Please continue to see Figure 1 According to an embodiment of the present application, the string quantity adjustment photovoltaic assembly 214 includes: a first photovoltaic assembly A1 to be adjusted, a second photovoltaic assembly A2 to be adjusted, a third photovoltaic assembly B1 to be adjusted, and a fourth photovoltaic assembly B2 to be adjusted.

[0063] The photovoltaic component 214 for adjusting the number of strings is the second part of the photovoltaic string 210, and the remaining photovoltaic components are the first part of the photovoltaic string 210. When the switch unit is in the off state, the photovoltaic component to be adjusted is connected to the first part of the photovoltaic string 210.

[0064] It should be noted that Figure 1The setting method of the switch unit is only one of them. There can be many other setting methods. There can be multiple photovoltaic modules to be adjusted, which can be adjacent or non-adjacent. They are not listed here one by one and can be determined according to the specific circumstances in the actual application scenario.

[0065] In one embodiment, when the first switch unit 142 and the second switch unit 144 are in the off state, the string quantity adjustment photovoltaic component 214 is connected to the first part 212 of the photovoltaic string 210 to increase the number of photovoltaic strings 210 in series after the reduction, which can also be understood as reducing the number of photovoltaic strings 210 in series. For example, the original number of photovoltaic strings 210 in series was reduced by 4, and now the number of photovoltaic strings 210 in series is reduced by 2, so the number of photovoltaic strings 210 in series is reduced by 4, but the overall number of photovoltaic strings 210 in series N is not increased. It is just that after the number of photovoltaic strings 210 in series is reduced, it is necessary to increase the photovoltaic components to be adjusted connected to the first part 212 of the photovoltaic string 210 in some cases. For example, the original number of photovoltaic components to be adjusted connected to the first part 212 of the photovoltaic string 210 is 2, and now it is necessary to increase 2 photovoltaic components to be adjusted connected to the first part 212 of the photovoltaic string 210.

[0066] In another embodiment, the plurality of photovoltaic components to be adjusted may not be adjacent, and may be separated in the photovoltaic string 210. For example, a switch unit is set at the first column of photovoltaic components in the photovoltaic string 210, a switch unit is set at the middle column of photovoltaic components, and a switch unit is set at the last column of photovoltaic components. These three columns of photovoltaic components are photovoltaic components for adjusting the number of strings and are not adjacent.

[0067] In this embodiment, a plurality of photovoltaic components to be adjusted are adjacent, and only one switch unit may be provided. Only one switch unit may be used to adjust the number of photovoltaic strings 210 in series, thereby reducing the number of switch units and simplifying the circuit structure.

[0068] The specific structure of the photovoltaic string series quantity adjustment control device 100 provided in the embodiment of the present application is introduced below through a specific embodiment.

[0069] See also Figure 2 , Figure 2 1 is a schematic block diagram of the specific structure of a photovoltaic string series quantity adjustment control device 100 of a photovoltaic string 210 provided in an embodiment of the present application. Figure 2 As shown, in one embodiment, the difference addition unit 150 includes: a first difference module 152 , a minimum voltage calculation module 154 , a second difference module 156 and a result addition module 158 .

[0070] The first input end of the first difference module 152 is connected to the first output end of the DC voltage acquisition unit 130, the second input end of the first difference module 152 is connected to the output end of the control system 230, and the output end of the first difference module 152 is connected to the first input end of the result superposition module 158. The first difference module 152 is used to perform a difference between the output voltage signal Vdc and the preset voltage signal Vdcmax to obtain a first type of difference result.

[0071] The first input terminal of the minimum voltage calculation module 154 is connected to the second output terminal of the temperature monitoring unit 120, the second input terminal of the minimum voltage calculation module 154 is connected to the output terminal of the control system 230, and the output terminal of the minimum voltage calculation module 154 is connected to the first input terminal of the second difference module 156. The minimum voltage calculation module 154 is used to calculate the minimum output voltage according to the temperature signal T, the preset voltage signal Vdcmax and the component equivalent open circuit voltage Voc' to obtain the minimum output voltage signal Vdc'.

[0072] The second input end of the second difference module 156 is connected to the second output end of the DC voltage acquisition unit 130, and the output end of the second difference module 156 is connected to the second input end of the result superposition module 158. The second difference module 156 is used to perform a difference between the output voltage signal Vdc and the minimum output voltage signal Vdc' to obtain a second type of difference result.

[0073] The output end of the result superposition module 158 is connected to the second input end of the control unit 110 . The result superposition module 158 is used to superimpose the first type of difference result and the second type of difference result to obtain a superposition signal.

[0074] See also Figure 3 , Figure 3 1 is a schematic block diagram of the specific structure of a photovoltaic string series quantity adjustment control device 100 of a photovoltaic string 210 provided in an embodiment of the present application. Figure 3 As shown, in one embodiment, the first difference module 152 subtracts Vdc-Vdcmax to obtain a first type difference result. The minimum voltage calculation module 154 calculates the minimum output voltage signal Vdc'=Vdcmax-2Voc', where Voc' is the equivalent open circuit voltage of the component. , Represents the open circuit voltage temperature coefficient of the component.

[0075] The second difference module 156 adds Vdc-Vdc' to obtain a second difference result, and the result superposition module 158 superimposes the first difference result and the second difference result to obtain a superposition signal.

[0076] Please continue to see Figure 2According to an implementation of the present application, the control unit 110 includes: a main control module 112 , a limit module 116 , a signal superposition module 118 and a PWM (Pulse Width Modulation) control module 114 .

[0077] The input end of the main control module 112 is connected to the output end of the difference superposition unit 150, and the output end of the main control module 112 is connected to the first input end of the signal superposition module 118. The main control module 112 is used to generate a first type of main control signal based on the first type of difference result, or generate a second type of main control signal based on the superposition signal.

[0078] The input end of the limit module 116 is connected to the first input end of the temperature monitoring unit 120, and the output end of the limit module 116 is connected to the second input end of the signal superposition module 118. The limit module 116 is used to generate a first limit signal 0 or a second limit signal 1 based on the temperature signal T.

[0079] The output end of the signal superposition module 118 is connected to the input end of the PWM control module 114, and the output end of the PWM control module 114 is connected to the control end of each switch unit. The signal superposition module 118 is used to perform a logical operation superposition on the temperature signal and the first type of main control signal according to the second limit signal 1 to generate a first type of modulation signal, or to perform a logical operation superposition on the temperature signal and the second type of main control signal to generate a second type of modulation signal.

[0080] The PWM control module 114 is used to generate a first type of driving signal based on the first type of modulation signal, or to generate a second type of driving signal based on the second type of modulation signal, and to control each switch unit to turn on or off based on the first type of driving signal or the second type of driving signal.

[0081] Please continue to see Figure 3 The main control module 112 is a PI (proportional integral) controller. The limit module 116 outputs a limit signal 0 or 1 by judging whether the temperature is greater than 25°C. When the temperature is greater than 25°C, the limit module 116 outputs a limit signal 0; when the temperature is less than or equal to 25°C, the limit module 116 outputs a limit signal 1. The PWM control module 114 is a PWM generator.

[0082] Please continue to see Figure 1According to an embodiment of the present application, the device 100 includes: a first switch unit 142 and a second switch unit 144. The control end of the first switch unit 142 is connected to the first output end of the control unit 110, the first controlled end of the first switch unit 142 is connected to the negative electrode of the first photovoltaic component A1 to be adjusted, and the second controlled end of the first switch unit 142 is connected to the positive electrode of the second photovoltaic component A2 to be adjusted.

[0083] In some embodiments, the first switch unit 142 is used to short-circuit the first photovoltaic component A1 to be adjusted and the second photovoltaic component A2 to be adjusted when in the on state, or to connect the first photovoltaic component A1 to be adjusted and the second photovoltaic component A2 to be adjusted when in the off state, and to connect the third photovoltaic component B1 to be adjusted and the fourth photovoltaic component B2 to be adjusted.

[0084] In one embodiment, the control end of the second switch unit 144 is connected to the second output end of the control unit 110, the first controlled end of the second switch unit 144 is connected to the negative pole of the third photovoltaic component B1 to be adjusted, and the second controlled end of the second switch unit 144 is connected to the positive pole of the fourth photovoltaic component B2 to be adjusted.

[0085] In some embodiments, the second switch unit 144 is used to short-circuit the third photovoltaic component B1 to be adjusted and the fourth photovoltaic component B2 to be adjusted when in the on state, or to connect the third photovoltaic component B1 to be adjusted and the fourth photovoltaic component B2 to be adjusted to the first part of the photovoltaic string 210 at the same time when in the off state.

[0086] When the third photovoltaic assembly to be adjusted B1 and the fourth photovoltaic assembly to be adjusted B2 are short-circuited, the first photovoltaic assembly to be adjusted A1 and the second photovoltaic assembly to be adjusted A2 are simultaneously disconnected from the first part of the photovoltaic string 210 .

[0087] Please continue to see Figure 2 According to an embodiment of the present application, the first switch unit 142 includes: a first switch device VD1 and a first diode D1, and the second switch unit 144 includes: a second switch device VD2 and a second diode D2.

[0088] In one embodiment, the control end of the first switching device VD1 is connected to the first output end of the control unit 110, the first controlled end of the first switching device VD1 is connected to the cathode of the first photovoltaic component A1 to be regulated, the second controlled end of the first switching device VD1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the anode of the second photovoltaic component A2 to be regulated.

[0089] The first diode D1 is used to prevent current from flowing backward, ie, from the positive electrode of the second photovoltaic component A2 to be regulated to the negative electrode of the first photovoltaic component A1 to be regulated.

[0090] In one embodiment, the control end of the second switching device VD2 is connected to the second output end of the control unit 110, the first controlled end of the second switching device VD2 is connected to the negative electrode of the third photovoltaic component B1 to be regulated, the second controlled end of the second switching device VD2 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the positive electrode of the fourth photovoltaic component to be regulated.

[0091] The second diode D2 is used to prevent current from flowing back, ie, from the positive electrode of the fourth photovoltaic component to be regulated B2 to the negative electrode of the third photovoltaic component to be regulated B1.

[0092] It should be noted that due to the action of the second diode D2, the current cannot flow backwards, and the first photovoltaic component A1 to be adjusted, the second photovoltaic component A2 to be adjusted, the third photovoltaic component B1 to be adjusted, and the fourth photovoltaic component B2 to be adjusted cannot form a loop, so they are disconnected from the first part 212 of the photovoltaic string 210, and the number of series connections of the photovoltaic string 210 is reduced.

[0093] Wherein, both the first switch device VD1 and the second switch device VD2 can be IGBTs, which are small in size, controllable, switchable, high in voltage resistance, highly integrated in driving circuits, and simple to control, and are preferred switch devices. The control end of the first switch device VD1 and the second switch device VD2 is the gate G, the first controlled end is the collector E, and the second controlled end is the emitter C.

[0094] Please continue to see Figure 2 According to one embodiment of the present application, the device 100 further includes a signal input unit 160. The input end of the signal input unit 160 is connected to the output end of the control system 230, and the output end of the signal input unit 160 is connected to the fourth input end of the differential superposition unit 150. The signal input unit 160 is used to input a fixed parameter output by the control system 230, such as a preset voltage signal Vdcmax, and output the preset voltage signal Vdcmax to the differential superposition unit 150.

[0095] See also Figure 4 , Figure 4 1 is a schematic block diagram of the overall structure of a photovoltaic string series quantity adjustment control device 100 for multiple photovoltaic strings 210 provided in an embodiment of the present application. Figure 3 As shown, the device 100 includes: a difference superposition unit 150, a control unit 110, a temperature monitoring unit 120, a DC voltage acquisition unit 130 and a plurality of switch units 141-14n.

[0096] The DC voltage acquisition unit 130 includes multiple input terminals and multiple first output terminals and second output terminals, the difference superposition unit 150 includes: multiple second input terminals and third input terminals, and the control unit 110 includes multiple output terminals. There are multiple photovoltaic strings 210 connected to the input terminal of the DC voltage acquisition unit 130, including photovoltaic strings 211~21n.

[0097] In one embodiment, the output end of the temperature monitoring unit 120 is connected to the first input end of the control unit 110 , and the temperature monitoring unit 120 is used to monitor the ambient temperature under the working conditions of each photovoltaic string 211 - 21 n to obtain a plurality of ambient temperature signals T1 -Tn.

[0098] In one embodiment, each input end of the DC voltage collection unit 130 is connected to the DC output end [including the positive and negative terminals (BUS1+, BUS1-)~(BUSn+, BUSn-)] of the photovoltaic strings 211~21n, each first output end of the DC voltage collection unit 130 is connected to each second input end of the differential superposition unit 150, and each second output end of the DC voltage collection unit 130 is connected to each third input end of the differential superposition unit 150. The DC voltage collection unit 130 is used to collect the output voltage signals VdcS1~VdcSn of each photovoltaic string 211~21n.

[0099] In one embodiment, the fourth input terminal and the fifth input terminal of the difference superposition unit 150 are connected to the output terminal of the external control system, and the output terminal of the difference superposition unit 150 is connected to the second input terminal of the control unit 110. The difference superposition unit 150 is used to perform difference between the output voltage signals VdcS1-VdcSn of each photovoltaic string 211-21n and the preset voltage signal Vdcmax to obtain a plurality of first-type difference results.

[0100] In another embodiment, the difference superposition unit 150 is also used to perform difference on each output voltage signal and the minimum output voltage signal while obtaining the first type of difference result to obtain multiple second type difference results, and superimpose each first type difference result with each second type difference result to obtain multiple superimposed signals.

[0101] In some embodiments, the output end of the control unit 110 is connected to the control end of each switch unit 141-14n. The control unit 110 is used to generate a corresponding first control signal according to each first-class difference result, or generate a corresponding second control signal according to each superposition signal, and control the corresponding switch unit to be turned on or off according to the first control signal and the second control signal.

[0102] In some embodiments, in each photovoltaic string 211-21n composed of N photovoltaic components connected in series, a switch unit is provided at least at one place. Each switch unit is connected in parallel to at least one photovoltaic component, and the control end of each switch unit is connected to the corresponding output end of the control unit 110. When each switch unit is in the on state, the photovoltaic component connected in parallel with it is short-circuited to reduce the number of series connections of the corresponding photovoltaic strings 211-21n. Among them, the photovoltaic components connected in parallel with each switch unit are adjusted for the corresponding number of strings.

[0103] In one embodiment, a photovoltaic string 211-21n composed of N photovoltaic modules connected in series in positive and negative directions is provided with switch units 141-14n. Each switch unit 141, 142-14(n-1), 14n is connected in parallel to the corresponding photovoltaic modules (A1 and A2), (B1 and B2)-(A1n and A2n), (B1n and B2n), and the control end of each switch unit 141, 142-14(n-1), 14n is connected to the corresponding output end of the control unit 110.

[0104] When each switch unit 141, 142~14(n-1), 14n is in the on state, the corresponding photovoltaic components (A1, A2, B1 and B2)~(A1n, A2n, B1n and B2n) are short-circuited to reduce the number of series-connected photovoltaic strings 211~21n. The photovoltaic components (A1, A2, B1 and B2)~(A1n, A2n, B1n and B2n) are the photovoltaic components 21111~2111n for adjusting the number of strings.

[0105] It should be noted that the specific structure of the photovoltaic string series quantity regulating control device 100 of multiple photovoltaic strings 211~21n is substantially the same as the specific structure of the photovoltaic string series quantity regulating control device 100 of one photovoltaic string 210, which will not be repeated here.

[0106] See also Figure 5 , Figure 5 2 is a schematic block diagram of a photovoltaic string series quantity adjustment control system 200 including a photovoltaic string 210 provided in an embodiment of the present application. Figure 5 As shown, the system 200 includes: a photovoltaic string 210, an inverter 220, a box-type transformer AC device 240, a control system 230 and a photovoltaic string series quantity adjustment control device 100.

[0107] In one embodiment, the DC input end of the PV string 210 (including the positive and negative terminals VIN+, VIN-) is connected to the output end of the PV string 210 series quantity adjustment device 100, and the DC output end of the PV string 210 (including the positive and negative terminals BUS+, BUS-) is connected to the power supply input end of the inverter 220 (including the positive and negative terminals N+, N-) and the first input end of the PV string 210 series quantity adjustment device 100.

[0108] The photovoltaic string 210 is used to provide an output voltage signal Vdc to the photovoltaic string 210 series connection quantity adjustment device 100 , and output direct current after adjusting the series connection quantity of the photovoltaic string 210 to the inverter 220 .

[0109] In one embodiment, the output end of the inverter 220 is connected to the input end of the box-type transformer AC device 240, and the inverter 220 is used to invert the direct current output by the photovoltaic string 210 into alternating current, and output the alternating current to the box-type transformer AC device 240. The inverter may be a DC-AC converter.

[0110] It should be noted that different product models of the inverter 220 have different numbers of MPPTs, and the number of photovoltaic strings that can be connected to the inverter 220 is also different.

[0111] In one embodiment, the input end of the box-type transformer AC device 240 is connected to the output end of the inverter 220, and the output end of the box-type transformer AC device 240 is connected to the input end of the power grid. The box-type transformer AC device 240 is used to collect and boost the AC power output by the inverter 220, and output the boosted AC power to the power grid.

[0112] In one embodiment, the output end of the control system 230 is connected to the second input end of the photovoltaic string 210 series connection quantity adjustment device 100, and the control system 230 is used to output a preset voltage signal Vdcmax to the photovoltaic string 210 series connection quantity adjustment device 100. The photovoltaic string series connection quantity adjustment control device 100 is used to adjust the series connection quantity of the photovoltaic string 210 based on the ambient temperature signal T under the working condition of the photovoltaic string 210, the output voltage signal Vdc provided by the photovoltaic string 210, and the preset voltage signal Vdcmax.

[0113] See also Figure 6 , Figure 6 2 is a schematic block diagram of a photovoltaic string series quantity adjustment control system 200 including a plurality of photovoltaic strings 211 to 21n provided in an embodiment of the present application. Figure 6As shown, the photovoltaic string series quantity regulation control system 200 includes: multiple photovoltaic strings 211~21n, an inverter 220, a control system 230, a box-type transformer AC device 240 and a photovoltaic string series quantity regulation control device 100 for multiple photovoltaic strings 211~21n.

[0114] Among them, the photovoltaic string series quantity adjustment control device 100 includes: multiple first input terminals, second input terminals and multiple output terminals, and the inverter 220 includes multiple power supply input terminals [including positive and negative terminals (N1+, N1-) ~ (Nn+, Nn-)].

[0115] In one embodiment, the DC input end of each photovoltaic string 211~21n [including the positive and negative terminals (VIN1+, VIN1-)~(VINn+, VINn-)] is connected to the output end corresponding to the photovoltaic string series quantity adjustment control device 100, and the DC output end of each photovoltaic string 211~21n [including the positive and negative terminals (BUS1+, BUS1-)~(BUSn+, BUSn-)] is connected to the power supply input end corresponding to the inverter 220 and the first input end corresponding to the photovoltaic string series quantity adjustment control device 100.

[0116] Each photovoltaic string 211 - 21 n is used to provide a corresponding output voltage signal VdcS1 - VdcSn to the photovoltaic string series quantity adjustment control device 100 , and output a corresponding direct current after adjusting the series quantity of the photovoltaic strings 211 - 21 n to the inverter 220 .

[0117] In one embodiment, the output end of the inverter 220 is connected to the input end of the box-type transformer AC device 240, and the inverter 220 is used to invert the DC power output by each photovoltaic string 211~21n into AC power, and output the AC power to the box-type transformer AC device 240. The output end of the box-type transformer AC device 240 is connected to the input end of the power grid, and the box-type transformer AC device 240 is used to collect and boost the AC power output by the inverter 220, and output the boosted AC power to the power grid.

[0118] In one embodiment, the output end of the control system 230 is connected to the second input end of the photovoltaic string series quantity adjustment control device 100, and the control system 230 is used to output a preset voltage signal Vdcmax to the photovoltaic string series quantity adjustment control device 100. The photovoltaic string series quantity adjustment control device 100 is used to adjust the series quantity of each photovoltaic string 211-21n based on the ambient temperature signals T1-Tn under the working conditions of each photovoltaic string 211-21n, the output voltage signals VdcS1-VdcSn provided by each photovoltaic string 211-21n, and the preset voltage signal Vdcmax.

[0119] See also Figure 7, Figure 7 1 is a schematic diagram of the process flow of automatic adjustment control of the number of photovoltaic strings connected in series provided by the embodiment of the present application. Figure 7 As shown, the control process includes the following steps: First, the controller determines whether the current ambient temperature is greater than 25°C. If the temperature is greater than 25°C, the controller controls the switching device not to operate and keeps the original design number of strings N unchanged; if the temperature is less than or equal to 25°C, it determines whether the string output voltage Vdc at the current temperature is greater than the maximum input voltage Vdcmax of the inverter.

[0120] If Vdc is greater than Vdcmax, the controller controls the switch device to actuate and reduce the number of strings N. If Vdc is less than or equal to Vdcmax, calculate the equivalent open-circuit voltage of the component at the current temperature. , ], Indicates the open circuit voltage of the PV module.

[0121] Using the equivalent open-circuit voltage Voc´ calculated in the previous step, the minimum output voltage of the string Vdc´=Vdcmax-2Voc´ is calculated.

[0122] Then, it is determined whether the string output voltage Vdc is less than or equal to Vdc´ at the current temperature. If Vdc is less than or equal to Vdc´, the controller controls the switch device to operate and increase the number of strings N. If Vdc is greater than Vdc´, the controller controls the switch device not to operate and keeps the current number of strings N unchanged.

[0123] When the ambient temperature continues to change, the above control process is executed cyclically.

[0124] In some embodiments, by analyzing the data in Table 1, the photovoltaic string series number automatic adjustment device 100 is based on the number of strings in series N calculated under the component standard test conditions. Under the standard test conditions, the test temperature is 25°C, and the STC (Standard Test Condition) irradiance is 1000W / m 2 .

[0125] In a cycle from t0 to t8, the temperature change trend over time is as follows Figure 8 As shown in the figure, the temperature of the environment decreases with the passage of time from t0 to t4, and then starts to rise again after it drops to t4. According to the change of the ambient temperature, the PWM control signal output by the controller to control the switching device to turn on and off is as follows: Fig. 9 shown.

[0126] like Fig. 9 As shown, the PWM control signal output by the controller to the first switch unit 142 is U g1, the PWM control signal output to the second switch unit 144 is U g2 At time t0-t1, the PWM control signals output by the controller to the first switch unit 142 and the second switch unit 144 are both 0, and the number of photovoltaic strings connected in series is N0; At time t1-t3, the PWM control signal output by the controller to the first switch unit 142 is 1, and the PWM control signal output to the second switch unit 144 is 0, at which time the number of photovoltaic strings connected in series is N1; at time t3-t5, the PWM control signal output by the controller to the first switch unit 142 is 0, and the PWM control signal output to the second switch unit 144 is 1, at which time the number of photovoltaic strings connected in series is N2; At time t5~t7, the PWM control signal output by the controller to the first switch unit 142 is 1, and the PWM control signal output to the second switch unit 144 is 0. At this time, the number of photovoltaic strings connected in series is N3; at time t7~t8, the PWM control signal output by the controller to the first switch unit 142 and the second switch unit 144 is 0. At this time, the number of photovoltaic strings connected in series is N4.

[0127] See also Fig.10 , Fig.10 The method is a schematic diagram of the steps of a photovoltaic string series quantity adjustment control method provided in an embodiment of the present application. The method is implemented based on a photovoltaic string series quantity adjustment control device 100 of a photovoltaic string 210, combined with Figure 1 and Fig.10 , the method comprises the following steps: S101 , the temperature monitoring unit 120 monitors the ambient temperature of the photovoltaic string 210 under working conditions to obtain a temperature signal T.

[0128] S102 , collecting the output voltage signal Vdc of the photovoltaic string 210 based on the DC voltage collection unit 130 .

[0129] S103, based on the difference superposition unit 150, the output voltage signal Vdc is subtracted from the preset voltage signal Vdcmax output by the control system 230 to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal Vdc is subtracted from the minimum output voltage signal Vdc' to obtain a second type of difference result, and the first type of difference result is superimposed with the second type of difference result to obtain a superimposed signal.

[0130] S104, the control unit 110 generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal.

[0131] S105 , when each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings 210 connected in series; wherein the photovoltaic components connected in parallel with each switch unit are the string number adjustment photovoltaic components 214 .

[0132] In one embodiment, when the first switch unit 142 and the second switch unit 144 are in the on state, the photovoltaic components A1, A2, B1 and B2 are short-circuited to reduce the number of series-connected photovoltaic strings 210; wherein the photovoltaic components A1, A2, B1 and B2 are the photovoltaic components 214 for adjusting the number of strings.

[0133] See also Figure 2 According to an embodiment of the present application, the difference superposition unit 150 includes: a first difference module 152, a minimum voltage calculation module 154, a second difference module 156 and a result superposition module 158. The control unit 110 includes: a main control module 112, a limit module 116, a signal superposition module 118 and a PWM control module 114, and the device 100 includes: a first switch unit 142 and a second switch unit 144.

[0134] The photovoltaic assembly 214 for adjusting the number of strings includes: a first photovoltaic assembly A1 to be adjusted, a second photovoltaic assembly A2 to be adjusted, a third photovoltaic assembly B1 to be adjusted, and a fourth photovoltaic assembly B2 to be adjusted. The photovoltaic assembly 214 for adjusting the number of strings is the second part of the photovoltaic string 210, and the remaining photovoltaic assemblies are the first part of the photovoltaic string 210. When each switch unit is in the off state, the photovoltaic assembly 214 for adjusting the number of strings is connected to the first part of the photovoltaic string 210. The device 100 also includes a signal input unit 160.

[0135] It should be noted that, under standard test conditions, the number of strings connected in series is calculated according to the above formula (1) as N0. At this time, the switch devices VD1 and VD2 are both in the off state, the first photovoltaic assembly A1 to be adjusted is connected to the second photovoltaic assembly A2 to be adjusted, the third photovoltaic assembly B1 to be adjusted is connected to the fourth photovoltaic assembly B2 to be adjusted, and the third photovoltaic assembly B1 to be adjusted and the fourth photovoltaic assembly B2 to be adjusted are simultaneously connected to the first part of the photovoltaic string 210.

[0136] At time t0, the current ambient temperature is higher than the temperature under the standard test conditions, the limiter outputs a 0 signal, and after interacting with the control signal generated by the PI controller, it outputs a modulation signal with an amplitude of 0, and the drive signal generated by the PWM controller is 0. At this time, the switching devices VD1 and VD2 receive the shutdown signal, and the switching devices do not act, so the number of strings at this time remains unchanged at N0.

[0137] Based on the difference superposition unit 150, the output voltage signal Vdc is subtracted from the preset voltage signal Vdcmax output by the control system 230 to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal Vdc is subtracted from the minimum output voltage signal Vdc' to obtain a second type of difference result, and the first type of difference result and the second type of difference result are superimposed to obtain a superimposed signal, including: When the first ambient temperature is lower than the standard test temperature, i.e. at time t1: The first subtraction module 152 performs subtraction on the first output voltage signal Vdc1 and the preset voltage signal Vdcmax inputted from the signal input unit 160 to obtain a first subtraction result, ie, a difference between Vdc1 and Vdcmax.

[0138] When the second ambient temperature is lower than the first ambient temperature, that is, at time t2: The second output voltage signal Vdc2 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain a second subtraction result, i.e., the difference between Vdc2 and Vdcmax. At the same time, the first minimum output voltage is calculated based on the minimum voltage calculation module 154, and the second output voltage signal Vdc2 is subtracted from the first minimum output voltage signal Vdc1' (Vdc1'=V dcmax -2V oc1 The second difference result and the third difference result are superimposed by the result superposition module 158 to obtain a first superposition signal.

[0139] When the third ambient temperature is lower than the second ambient temperature, that is, at time t3: The first subtraction module 152 performs subtraction on the third output voltage signal Vdc3 and the preset voltage signal Vdcmax to obtain a fourth subtraction result, ie, the difference between Vdc3 and Vdcmax.

[0140] When the fourth ambient temperature is lower than the third ambient temperature, that is, at time t4: The fourth output voltage signal Vdc4 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain a fifth subtraction result, i.e., the difference between Vdc4 and Vdcmax. At the same time, the second minimum output voltage is calculated based on the minimum voltage calculation module 154, and the fourth output voltage signal Vdc4 is compared with the second minimum output voltage signal Vdc2' (Vdc2'=V dcmax -2V oc2 The fifth difference result and the sixth difference result are superimposed on each other by the result superimposition module 158 to obtain a second superimposed signal.

[0141] Among them, the first type of difference results include: the first difference result, the second difference result, the fourth difference result and the fifth difference result, and the second type of difference results include: the third difference result and the sixth difference result.

[0142] According to an embodiment of the present application, the output voltage signal Vdc is subtracted from the preset voltage signal Vdcmax output by the control system 230 based on the subtraction and superposition unit 150 to obtain a first type of subtraction result, or while obtaining the first type of subtraction result, the output voltage signal Vdc is subtracted from the minimum output voltage signal Vdc' to obtain a second type of subtraction result, and the first type of subtraction result and the second type of subtraction result are superimposed to obtain a superimposed signal, further comprising: When the fifth ambient temperature is greater than the fourth ambient temperature, that is, at time t5: The fifth output voltage signal Vdc5 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain a seventh subtraction result, namely, the difference between Vdc5 and Vdcmax. At the same time, the third lowest output voltage is calculated based on the lowest voltage calculation module 154, and the fifth output voltage signal Vdc5 is compared with the third lowest output voltage signal Vdc3' (Vdc3'=V dcmax -2×2V oc3 The seventh difference result and the eighth difference result are superimposed on each other by the result superposition module 158 to obtain a third superposition signal.

[0143] When the sixth ambient temperature is greater than the fifth ambient temperature, that is, at time t6: The sixth output voltage signal Vdc6 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain a ninth subtraction result, namely, the difference between Vdc6 and Vdcmax. At the same time, the fourth lowest output voltage is calculated based on the minimum voltage calculation module 154, and the sixth output voltage signal Vdc6 is compared with the fourth lowest output voltage signal Vdc4' (Vdc4'=V dcmax -2V oc4 The ninth difference result is superimposed on the tenth difference result by the result superposition module 158 to obtain a fourth superposition signal.

[0144] When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature, that is, at time t7: The seventh output voltage signal Vdc7 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain an eleventh subtraction result, namely, the difference between Vdc7 and Vdcmax. At the same time, the fifth minimum output voltage is calculated based on the minimum voltage calculation module 154, and the seventh output voltage signal Vdc7 is compared with the fifth minimum output voltage signal Vdc5' (Vdc5'=V dcmax -2×2V oc5 The eleventh difference result and the twelfth difference result are superimposed based on the result superposition module 158 to obtain a fifth superposition signal.

[0145] When the eighth ambient temperature is greater than the standard test temperature, that is, at time t8: The eighth output voltage signal Vdc8 is subtracted from the preset voltage signal Vdcmax based on the first subtraction module 152 to obtain a thirteenth subtraction result, i.e., the difference between Vdc8 and Vdcmax. At the same time, the sixth lowest output voltage is calculated based on the minimum voltage calculation module 154, and the eighth output voltage signal Vdc8 is subtracted from the sixth lowest output voltage signal Vdc6' to obtain a fourteenth subtraction result, i.e., the difference between Vdc8 and Vdc6'. The thirteenth subtraction result is superimposed with the fourteenth subtraction result based on the result superposition module 158 to obtain a sixth superposition signal.

[0146] Among them, the first category of difference results also includes: the seventh difference result, the ninth difference result, the eleventh difference result and the thirteenth difference result, and the second category of difference results also includes: the eighth difference result, the tenth difference result, the twelfth difference result and the fourteenth difference result.

[0147] According to an embodiment of the present application, the device 100 includes: a first switch unit 142 and a second switch unit 144. Based on the control unit 110, a first control signal is generated according to the first type of difference result, or a second control signal is generated according to the superposition signal, and the corresponding switch unit is controlled to be turned on or off based on the first control signal or the second control signal. When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings 210 in series. When each switch unit is in the off state, the photovoltaic components 214 for adjusting the number of strings are connected to the first part of the photovoltaic strings 210, including: When the first ambient temperature is lower than the standard test temperature: Based on the main control module 112, a first main control signal is generated according to the first difference result, and based on the limit module 116, a second limit signal 1 is generated according to the first temperature signal T. Based on the signal superposition module 118, the first temperature signal T is logically superimposed on the first main control signal according to the second limit signal 1 to generate a first modulation signal. Based on the PWM control module 114, a first drive signal is generated according to the first modulation signal, and the first switch unit 142 is controlled to be turned on according to the first drive signal to short-circuit the first photovoltaic component A1 to be adjusted and the second photovoltaic component A2 to be adjusted, and at the same time, the second switch unit 144 is driven to be turned off according to the first drive signal to connect the third photovoltaic component B1 to be adjusted and the fourth photovoltaic component B2 to be adjusted to the first part of the photovoltaic string 210 at the same time. At this time, the number of photovoltaic strings connected in series N1<N0, and the number of photovoltaic strings connected in series is reduced.

[0148] When the second ambient temperature is lower than the first ambient temperature: The main control module 112 generates a second main control signal according to the first superposition signal, and the limit module 116 generates a second limit signal 1 according to the second temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the second temperature signal T and the second main control signal according to the second limit signal 1 to generate a second modulation signal. The PWM control module 114 generates a second drive signal according to the second modulation signal, and controls the first switch unit 142 to turn on according to the second drive signal, and drives the second switch unit 144 to turn off according to the second drive signal. At this time, the number of photovoltaic strings connected in series is N1, which remains unchanged.

[0149] When the third ambient temperature is lower than the second ambient temperature: Based on the main control module 112, a third main control signal is generated according to the fourth difference result, and based on the limit module 116, a second limit signal 1 is generated according to the third temperature signal T. Based on the signal superposition module 118, according to the second limit signal 1, the third temperature signal T and the third main control signal are logically superimposed to generate a third modulation signal. Based on the PWM control module 114, a third drive signal is generated according to the third modulation signal, and the first switch unit 142 is controlled to be turned off according to the third drive signal, and the second switch unit 144 is controlled to be turned on according to the third drive signal, so as to short-circuit the third photovoltaic component B1 to be adjusted and the fourth photovoltaic component B2 to be adjusted. At this time, the number of photovoltaic strings connected in series N2<N1<N0, and the number of photovoltaic strings connected in series is reduced.

[0150] When the fourth ambient temperature is lower than the third ambient temperature: The main control module 112 generates a fourth main control signal according to the second superposition signal, and the limit module 116 generates a second limit signal 1 according to the fourth temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the fourth temperature signal T and the fourth main control signal according to the second limit signal 1 to generate a fourth modulation signal. The PWM control module 114 generates a fourth drive signal according to the fourth modulation signal, and controls the first switch unit 142 to turn off according to the fourth drive signal, and controls the second switch unit 144 to turn on according to the fourth drive signal. At this time, the number of photovoltaic strings connected in series is N2, which remains unchanged.

[0151] The first type of main control signal includes: a first main control signal and a third main control signal, and the second type of main control signal includes: a second main control signal and a fourth main control signal.

[0152] According to an embodiment of the present application, the control unit 110 generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal or the second control signal. When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of series connections of the photovoltaic string 210. When each switch unit is in the off state, the photovoltaic component 214 for adjusting the number of strings is connected to the first part of the photovoltaic string 210, and further includes: When the fifth ambient temperature is greater than the fourth ambient temperature: The main control module 112 generates a fifth main control signal according to the third superposition signal, and the limit module 116 generates a second limit signal 1 according to the fifth temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the fifth temperature signal T and the fifth main control signal according to the second limit signal 1 to generate a fifth modulation signal. The PWM control module 114 generates a fifth drive signal according to the fifth modulation signal, and controls the first switch unit 142 to turn on according to the fifth drive signal, and drives the second switch unit 144 to turn off according to the fifth drive signal. At this time, the number of photovoltaic strings connected in series N3=N1, and the number of photovoltaic strings connected in series increases on the basis of N2.

[0153] When the sixth ambient temperature is greater than the fifth ambient temperature: The main control module 112 generates a sixth main control signal according to the fourth superposition signal, and the limit module 116 generates a second limit signal 1 according to the sixth temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the sixth temperature signal T and the sixth main control signal according to the second limit signal 1 to generate a sixth modulation signal, and the PWM control module 114 generates a sixth drive signal according to the sixth modulation signal, and controls the first switch unit 142 to turn on according to the sixth drive signal, and drives the second switch unit 144 to turn off according to the sixth drive signal. At this time, the number of photovoltaic strings connected in series is N3, which remains unchanged.

[0154] When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature: The main control module 112 generates a seventh main control signal according to the fifth superposition signal, and the limit module 116 generates a second limit signal 1 according to the seventh temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the seventh temperature signal T and the seventh main control signal according to the second limit signal 1 to generate a seventh modulation signal. The PWM control module 114 generates a seventh drive signal according to the seventh modulation signal, and controls the first switch unit 142 and the second switch unit 144 to turn off according to the seventh drive signal. At this time, the number of photovoltaic strings connected in series N4=N0, and the number of photovoltaic strings connected in series increases on the basis of N3.

[0155] When the eighth ambient temperature is greater than the standard test temperature: The main control module 112 generates an eighth main control signal according to the sixth superposition signal, and the limit module 116 generates a first limit signal 0 according to the eighth temperature signal T. The signal superposition module 118 performs a logical operation and superposition on the eighth temperature signal T and the eighth main control signal according to the first limit signal 0 to generate an eighth modulation signal. The PWM control module 114 generates an eighth drive signal according to the eighth modulation signal, and controls the first switch unit 142 and the second switch unit 144 to turn off according to the eighth drive signal. At this time, the number of photovoltaic strings connected in series is N0, which remains unchanged.

[0156] The second type of main control signal further includes: a fifth main control signal, a sixth main control signal, a seventh main control signal and an eighth main control signal.

[0157] See also Fig.11 , Fig.11 1 is a schematic diagram of the steps of a method for adjusting the number of photovoltaic strings connected in series of multiple photovoltaic strings (211-21n) provided in an embodiment of the present application. The method is implemented based on a device 100 for adjusting the number of photovoltaic strings connected in series of multiple photovoltaic strings (211-21n), such as Fig.11 As shown, the method comprises the following steps: S111 , the temperature monitoring unit 120 monitors the ambient temperature of each photovoltaic string 210 under working conditions to obtain a plurality of temperature signals T.

[0158] S112 , collecting output voltage signals Vdc of each photovoltaic string 210 based on the DC voltage collection unit 130 .

[0159] S113, based on the difference superposition unit 150, the output voltage signal Vdc of each photovoltaic string 210 is subtracted from the preset voltage signal Vdcmax to obtain multiple first-type difference results, or while obtaining the first-type difference results, each output voltage signal Vdc is subtracted from the minimum output voltage signal Vdc' to obtain multiple second-type difference results, and each first-type difference result is superimposed with each second-type difference result to obtain multiple superimposed signals.

[0160] S114, the control unit 110 generates a corresponding first control signal according to each first-type difference result, or generates a corresponding second control signal according to each superposition signal, and controls the corresponding switch unit to be turned on or off according to the first control signal and the second control signal.

[0161] S115, when each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of series-connected photovoltaic strings 210; wherein the photovoltaic components connected in parallel with each switch unit are adjusted to the corresponding number of strings 214.

[0162] It should be noted that the implementation principle of this embodiment is substantially the same as that of the method for adjusting the number of photovoltaic strings connected in series for one photovoltaic string, except that it is replaced by multiple photovoltaic strings, which will not be repeated here.

[0163] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0164] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0165] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A photovoltaic string series quantity adjustment control device, characterized in that: The device comprises: a difference superposition unit, a control unit, a temperature monitoring unit, a DC voltage collection unit and a switch unit; The first output end of the temperature monitoring unit is connected to the first input end of the control unit, the second output end of the temperature monitoring unit is connected to the first input end of the difference superposition unit, and the temperature monitoring unit is used to monitor the ambient temperature under the working conditions of the photovoltaic string to obtain a temperature signal; The input end of the DC voltage acquisition unit is connected to the DC output end of the photovoltaic string, the first output end of the DC voltage acquisition unit is connected to the second input end of the differential superposition unit, the second output end of the DC voltage acquisition unit is connected to the third input end of the differential superposition unit, and the DC voltage acquisition unit is used to collect the output voltage signal of the photovoltaic string; The fourth input end of the difference superposition unit is connected to the output end of the control system in the photovoltaic string series quantity regulation control system, and the output end of the difference superposition unit is connected to the second input end of the control unit. The difference superposition unit is used to perform a difference between the output voltage signal and the preset voltage signal output by the control system to obtain a first type of difference result, or, while obtaining the first type of difference result, perform a difference between the output voltage signal and the minimum output voltage signal to obtain a second type of difference result, and superimpose the first type of difference result and the second type of difference result to obtain a superimposed signal; The output end of the control unit is connected to the control end of the switch unit, and the control unit is used to generate a first control signal according to the first type of difference result, or generate a second control signal according to the superposition signal, and control the corresponding switch unit to be turned on or off based on the first control signal and the second control signal; In a photovoltaic string consisting of N photovoltaic modules connected in series, the switch unit is provided at least at one location, each switch unit is connected in parallel to at least one photovoltaic module, and when each switch unit is in the on state, the photovoltaic module connected in parallel therewith is short-circuited to reduce the number of photovoltaic strings connected in series; The photovoltaic components connected in parallel with each switch unit are photovoltaic components for adjusting the number of strings.

2. The photovoltaic string series quantity adjustment control device according to claim 1 is characterized in that: The photovoltaic assembly for adjusting the number of strings includes: a first photovoltaic assembly to be adjusted, a second photovoltaic assembly to be adjusted, a third photovoltaic assembly to be adjusted, and a fourth photovoltaic assembly to be adjusted, which are adjacent to each other; The photovoltaic components for adjusting the number of strings are the second part of the photovoltaic strings, and the remaining photovoltaic components are the first part of the photovoltaic strings. When the switch unit is in the off state, the photovoltaic components to be adjusted are connected to the first part of the photovoltaic strings.

3. The photovoltaic string series quantity adjustment control device according to claim 1, characterized in that: The difference superposition unit comprises: a first difference module, a minimum voltage calculation module, a second difference module and a result superposition module; The first input end of the first difference module is connected to the first output end of the DC voltage acquisition unit, the second input end of the first difference module is connected to the output end of the control system, the output end of the first difference module is connected to the first input end of the result superposition module, and the first difference module is used to perform a difference between the output voltage signal and the preset voltage signal to obtain the first type of difference result; The first input end of the minimum voltage calculation module is connected to the second output end of the temperature monitoring unit, the second input end of the minimum voltage calculation module is connected to the output end of the control system, the output end of the minimum voltage calculation module is connected to the first input end of the second difference module, and the minimum voltage calculation module is used to calculate the minimum output voltage according to the temperature signal, the preset voltage signal and the component equivalent open circuit voltage to obtain a minimum output voltage signal; The second input end of the second difference module is connected to the second output end of the DC voltage acquisition unit, the output end of the second difference module is connected to the second input end of the result superposition module, and the second difference module is used to perform a difference between the output voltage signal and the minimum output voltage signal to obtain the second type of difference result; The output end of the result superposition module is connected to the second input end of the control unit, and the result superposition module is used to superimpose the first type of difference result and the second type of difference result to obtain the superposition signal.

4. The photovoltaic string series quantity adjustment control device according to claim 1, characterized in that: The control unit includes: a main control module, a limit module, a signal superposition module and a PWM control module; The input end of the main control module is connected to the output end of the difference superposition unit, the output end of the main control module is connected to the first input end of the signal superposition module, and the main control module is used to generate a first type of main control signal based on the first type of difference result, or generate a second type of main control signal based on the superposition signal; The input end of the limit module is connected to the first input end of the temperature monitoring unit, the output end of the limit module is connected to the second input end of the signal superposition module, and the limit module is used to generate a first limit signal or a second limit signal based on the temperature signal; The output end of the signal superposition module is connected to the input end of the PWM control module, and the output end of the PWM control module is connected to the control end of each switch unit. The signal superposition module is used to perform a logical operation superposition on the temperature signal and the first type of main control signal according to the second limit signal to generate a first type of modulation signal, or to perform a logical operation superposition on the temperature signal and the second type of main control signal to generate a second type of modulation signal; The PWM control module is used to generate a first type of drive signal based on the first type of modulation signal, or to generate a second type of drive signal based on the second type of modulation signal, and to control each switch unit to turn on or off based on the first type of drive signal or the second type of drive signal.

5. The photovoltaic string series quantity adjustment control device according to claim 2, characterized in that: The device comprises: a first switch unit and a second switch unit; The control end of the first switch unit is connected to the first output end of the control unit, the first controlled end of the first switch unit is connected to the negative electrode of the first photovoltaic component to be adjusted, and the second controlled end of the first switch unit is connected to the positive electrode of the second photovoltaic component to be adjusted. The first switch unit is used to short-circuit the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted when it is in the on state, or connect the first photovoltaic component to be adjusted with the second photovoltaic component to be adjusted, and connect the third photovoltaic component to be adjusted with the fourth photovoltaic component to be adjusted when it is in the off state; The control end of the second switch unit is connected to the second output end of the control unit, the first controlled end of the second switch unit is connected to the negative electrode of the third photovoltaic component to be adjusted, and the second controlled end of the second switch unit is connected to the positive electrode of the fourth photovoltaic component to be adjusted. The second switch unit is used to short-circuit the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted when it is in the on state, or to connect the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted to the first part of the photovoltaic string at the same time when it is in the off state; Wherein, when the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted are short-circuited, the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted are simultaneously disconnected from the first part of the photovoltaic string.

6. The photovoltaic string series quantity adjustment control device according to claim 5, characterized in that: The first switch unit includes: a first switch device and a first diode, and the second switch unit includes: a second switch device and a second diode; The control end of the first switch device is connected to the first output end of the control unit, the first controlled end of the first switch device is connected to the negative electrode of the first photovoltaic component to be regulated, the second controlled end of the first switch device is connected to the anode of the first diode, the cathode of the first diode is connected to the positive electrode of the second photovoltaic component to be regulated, and the first diode is used to prevent current from flowing from the positive electrode of the second photovoltaic component to be regulated to the negative electrode of the first photovoltaic component to be regulated; The control end of the second switching device is connected to the second output end of the control unit, the first controlled end of the second switching device is connected to the negative electrode of the third photovoltaic component to be regulated, the second controlled end of the second switching device is connected to the anode of the second diode, the cathode of the second diode is connected to the positive electrode of the fourth photovoltaic component to be regulated, and the second diode is used to prevent current from flowing from the positive electrode of the fourth photovoltaic component to be regulated to the negative electrode of the third photovoltaic component to be regulated.

7. The photovoltaic string series quantity adjustment control device according to claim 1, characterized in that: The device also includes a signal input unit; The input end of the signal input unit is connected to the output end of the control system, and the output end of the signal input unit is connected to the fourth input end of the differential superposition unit. The signal input unit is used to input a preset voltage signal output by the control system and output the preset voltage signal to the differential superposition unit.

8. The photovoltaic string series quantity adjustment control device according to any one of claims 1 to 7, characterized in that: The device comprises: a differential superposition unit, a control unit, a temperature monitoring unit, a DC voltage acquisition unit and a plurality of switch units; wherein the DC voltage acquisition unit comprises a plurality of input terminals and a plurality of first output terminals and a second output terminal, the differential superposition unit comprises: a plurality of second input terminals and a third input terminal, the control unit comprises a plurality of output terminals, and there are a plurality of photovoltaic strings connected to the input terminal of the DC voltage acquisition unit; The first output end of the temperature monitoring unit is connected to the first input end of the control unit, the second output end of the temperature monitoring unit is connected to the first input end of the difference superposition unit, and the temperature monitoring unit is used to monitor the ambient temperature under the working conditions of each photovoltaic string to obtain multiple temperature signals; Each input end of the DC voltage collection unit is connected to the DC output end of the corresponding photovoltaic string, each first output end of the DC voltage collection unit is connected to each second input end of the difference superposition unit, each second output end of the DC voltage collection unit is connected to each third input end of the difference superposition unit, and the DC voltage collection unit is used to collect the output voltage signal of each photovoltaic string; The fourth input terminal and the fifth input terminal of the difference superposition unit are connected to the output terminal of the external control system, and the output terminal of the difference superposition unit is connected to the second input terminal of the control unit. The difference superposition unit is used to perform difference between the output voltage signal of each photovoltaic string and the preset voltage signal to obtain a plurality of first-type difference results, or, while obtaining the first-type difference results, perform difference between each output voltage signal and the lowest output voltage signal to obtain a plurality of second-type difference results, and superimpose each first-type difference result and each second-type difference result to obtain a plurality of superimposed signals; The output end of the control unit is connected to the control end of the switch unit, and the control unit is used to generate a corresponding first control signal according to each first-class difference result, or generate a corresponding second control signal according to each superposition signal, and control the corresponding switch unit to be turned on or off according to the first control signal and the second control signal; In each photovoltaic string composed of N photovoltaic modules connected in series, a switch unit is provided at least at one location, each switch unit is connected in parallel to at least one photovoltaic module, and when each switch unit is in the on state, the photovoltaic module connected in parallel therewith is short-circuited to reduce the number of series connections of the corresponding photovoltaic strings; wherein the photovoltaic modules connected in parallel to each switch unit are adjusted for the corresponding number of strings.

9. A photovoltaic string series quantity regulation control system, characterized in that: The system comprises: a photovoltaic string, an inverter, a box-type transformer AC device, a control system, and a photovoltaic string series quantity adjustment control device according to any one of claims 1 to 7; The DC input end of the photovoltaic string is connected to the output end of the photovoltaic string series quantity adjustment control device, and the DC output end of the photovoltaic string is connected to the power supply input end of the inverter and the first input end of the photovoltaic string series quantity adjustment control device. The photovoltaic string is used to provide an output voltage signal to the photovoltaic string series quantity adjustment control device and output direct current after adjusting the number of photovoltaic strings in series to the inverter; The output end of the inverter is connected to the input end of the box-type transformer AC device. The inverter is used to invert the DC power output by the photovoltaic string into AC power and output the AC power to the box-type transformer AC device. The output end of the box-type transformer AC device is connected to the input end of the power grid. The box-type transformer AC device is used to collect and boost the AC power output by the inverter, and output the boosted AC power to the power grid; The output end of the control system is connected to the second input end of the photovoltaic string series quantity adjustment control device, and the control system is used to output a preset voltage signal to the photovoltaic string series quantity adjustment control device; The photovoltaic string series quantity adjustment control device is used to adjust the number of photovoltaic strings in series based on the ambient temperature signal under the working conditions of the photovoltaic strings, the output voltage signal provided by the photovoltaic strings and the preset voltage signal.

10. The photovoltaic string series quantity regulation control system according to claim 9, characterized in that: The system comprises: a plurality of photovoltaic strings, an inverter, a box-type transformer AC device, a control system and the photovoltaic string series quantity adjustment control device according to claim 8; wherein the photovoltaic string series quantity adjustment control device comprises a plurality of first input terminals, a second input terminal and a plurality of output terminals, and the inverter comprises a plurality of power supply input terminals; The DC input end of each photovoltaic string is connected to the output end corresponding to the photovoltaic string series quantity adjustment control device, and the DC output end of each photovoltaic string is connected to the power supply input end corresponding to the inverter and the first input end corresponding to the photovoltaic string series quantity adjustment control device. Each photovoltaic string is used to provide the corresponding output voltage to the photovoltaic string series quantity adjustment control device and output the corresponding DC power after adjusting the photovoltaic string series quantity to the inverter; The output end of the inverter is connected to the input end of the box-type transformer AC device. The inverter is used to invert the DC power output by each photovoltaic string into AC power and output the AC power to the box-type transformer AC device. The output end of the box-type transformer AC device is connected to the input end of the power grid. The box-type transformer AC device is used to collect and boost the AC power output by the inverter, and output the boosted AC power to the power grid; The output end of the control system is connected to the second input end of the photovoltaic string series quantity adjustment control device, and the control system is used to output a preset voltage signal to the photovoltaic string series quantity adjustment control device; The photovoltaic string series quantity adjustment control device is used to adjust the series quantity of each photovoltaic string based on the ambient temperature signal under the working conditions of each photovoltaic string, the output voltage signal provided by each photovoltaic string and the preset voltage signal.

11. A method for adjusting and controlling the number of photovoltaic strings in series, characterized in that: The method is implemented based on the photovoltaic string series quantity adjustment control device according to any one of claims 1 to 7, and comprises: Based on the temperature monitoring unit, the ambient temperature under the working condition of the photovoltaic string is monitored to obtain a temperature signal; The output voltage signal of the photovoltaic string is collected based on the DC voltage collection unit; Based on the difference superposition unit, the output voltage signal is subtracted from the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal is subtracted from the minimum output voltage signal to obtain a second type of difference result, and the first type of difference result and the second type of difference result are superimposed to obtain a superimposed signal; Based on the control unit generating a first control signal according to the first type of difference result, or generating a second control signal according to the superposition signal, and controlling the corresponding switch unit to be turned on or off based on the first control signal and the second control signal; When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings connected in series; wherein the photovoltaic components connected in parallel with each switch unit are photovoltaic components for adjusting the number of strings.

12. The photovoltaic string series quantity adjustment control method according to claim 11, characterized in that: The difference superposition unit includes: a first difference module, a minimum voltage calculation module, a second difference module and a result superposition module; the control unit includes: a main control module, a limit module, a signal superposition module and a PWM control module, the device includes: a first switch unit and a second switch unit; the string quantity adjustment photovoltaic assembly includes: adjacent first photovoltaic assemblies to be adjusted, second photovoltaic assemblies to be adjusted, third photovoltaic assemblies to be adjusted and fourth photovoltaic assemblies to be adjusted, the string quantity adjustment photovoltaic assembly is the second part of the photovoltaic string, and the remaining photovoltaic assemblies are the first part of the photovoltaic string. When each switch unit is in the off state, the string quantity adjustment photovoltaic assembly is connected to the first part of the photovoltaic string; the device also includes a signal input unit; based on the difference superposition unit, the output voltage signal is subtracted from the preset voltage signal output by the control system to obtain a first type of difference result, or while obtaining the first type of difference result, the output voltage signal is subtracted from the minimum output voltage signal to obtain a second type of difference result, and the first type of difference result is superimposed with the second type of difference result to obtain a superposition signal, including: When the first ambient temperature is lower than the standard test temperature: Subtracting the first output voltage signal from the preset voltage signal input by the signal input unit based on the first subtraction module to obtain a first subtraction result; When the second ambient temperature is lower than the first ambient temperature: Based on the first difference module, the second output voltage signal and the preset voltage signal are subtracted to obtain a second difference result, and at the same time, the first minimum output voltage is calculated based on the minimum voltage calculation module, and the second output voltage signal and the first minimum output voltage signal are subtracted based on the second difference module to obtain a third difference result, and the second difference result and the third difference result are superimposed based on the result superposition module to obtain a first superposition signal; When the third ambient temperature is lower than the second ambient temperature: Subtracting the third output voltage signal from the preset voltage signal based on the first subtraction module to obtain a fourth subtraction result; When the fourth ambient temperature is lower than the third ambient temperature: Based on the difference superposition unit, while obtaining the fifth difference result, the fourth output voltage signal and the second lowest output voltage signal are subtracted to obtain a sixth difference result, and based on the result superposition module, the fifth difference result and the sixth difference result are superimposed to obtain a second superposition signal; Among them, the first type of difference results includes: a first difference result, a second difference result, a fourth difference result and a fifth difference result, and the second type of difference results includes: a third difference result and a sixth difference result.

13. The photovoltaic string series quantity adjustment control method according to claim 12, characterized in that: The output voltage signal is subtracted from a preset voltage signal output by the control system based on a subtracting and superimposing unit to obtain a first type of subtracting result, or while obtaining the first type of subtracting result, the output voltage signal is subtracted from a minimum output voltage signal to obtain a second type of subtracting result, and the first type of subtracting result and the second type of subtracting result are superimposed to obtain a superimposed signal, further comprising: When the fifth ambient temperature is greater than the fourth ambient temperature: Based on the difference superposition unit, while obtaining the seventh difference result, the fifth output voltage signal and the third lowest output voltage signal are subtracted to obtain an eighth difference result, and based on the result superposition module, the seventh difference result and the eighth difference result are superimposed to obtain a third superposition signal; When the sixth ambient temperature is greater than the fifth ambient temperature: Based on the difference superposition unit, while obtaining the ninth difference result, the sixth output voltage signal and the fourth lowest output voltage signal are subtracted to obtain a tenth difference result, and based on the result superposition module, the ninth difference result and the tenth difference result are superimposed to obtain a fourth superposition signal; When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature: Based on the difference superposition unit, while obtaining the eleventh difference result, the seventh output voltage signal and the fifth lowest output voltage signal are subtracted to obtain a twelfth difference result, and based on the result superposition module, the eleventh difference result and the twelfth difference result are superimposed to obtain a fifth superposition signal; When the eighth ambient temperature is greater than the standard test temperature: Based on the difference superposition unit, while obtaining the thirteenth difference result, the eighth output voltage signal and the sixth lowest output voltage signal are subtracted to obtain a fourteenth difference result, and based on the result superposition module, the thirteenth difference result and the fourteenth difference result are superimposed to obtain a sixth superposition signal; Among them, the first category of difference results also includes: the seventh difference result, the ninth difference result, the eleventh difference result and the thirteenth difference result, and the second category of difference results also includes: the eighth difference result, the tenth difference result, the twelfth difference result and the fourteenth difference result.

14. The photovoltaic string series quantity adjustment control method according to claim 12, characterized in that: The device comprises: a first switch unit and a second switch unit; the control unit generates a first control signal according to the first type of difference result, or generates a second control signal according to the superposition signal, and controls the corresponding switch unit to be turned on or off based on the first control signal and the second control signal, and when each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings in series, and when each switch unit is in the off state, the photovoltaic components for adjusting the number of strings are connected to the first part of the photovoltaic strings, including: When the first ambient temperature is lower than the standard test temperature: Based on the main control module, a first main control signal is generated according to the first difference result; based on the limit module, a second limit signal is generated according to the first temperature signal; based on the signal superposition module, the first temperature signal is logically superimposed on the first main control signal according to the second limit signal to generate a first modulation signal; based on the PWM control module, a first drive signal is generated according to the first modulation signal; and according to the first drive signal, the first switch unit is controlled to be turned on to short-circuit the first photovoltaic component to be adjusted and the second photovoltaic component to be adjusted, and at the same time, the second switch unit is driven to be turned off according to the first drive signal to connect the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted to the first part of the photovoltaic string at the same time; When the second ambient temperature is lower than the first ambient temperature: Based on the control unit, a second drive signal is generated according to the first superimposed signal, and the first switch unit is controlled to be turned on according to the second drive signal, and the second switch unit is driven to be turned off according to the second drive signal; When the third ambient temperature is lower than the second ambient temperature: Based on the control unit generating a third driving signal according to the fourth difference result, and controlling the first switch unit to be turned off according to the third driving signal, and controlling the second switch unit to be turned on according to the third driving signal, so as to short-circuit the third photovoltaic component to be adjusted and the fourth photovoltaic component to be adjusted; When the fourth ambient temperature is lower than the third ambient temperature: Based on the control unit, a fourth drive signal is generated according to the second superimposed signal, and the first switch unit is controlled to be turned off according to the fourth drive signal, and the second switch unit is controlled to be turned on according to the fourth drive signal; The first type of main control signal includes a first main control signal.

15. The photovoltaic string series quantity adjustment control method according to claim 13, characterized in that: Based on the control unit generating a first control signal according to the first type of difference result, or generating a second control signal according to the superposition signal, and controlling the corresponding switch unit to be turned on or off based on the first control signal and the second control signal, when each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of photovoltaic strings in series, and when each switch unit is in the off state, the photovoltaic components for adjusting the number of strings are connected to the first part of the photovoltaic strings, and further comprising: When the fifth ambient temperature is greater than the fourth ambient temperature: generating a fifth drive signal based on the control unit according to the third superimposed signal, and controlling the first switch unit to be turned on according to the fifth drive signal, and driving the second switch unit to be turned off according to the fifth drive signal; When the sixth ambient temperature is greater than the fifth ambient temperature: generating a sixth drive signal based on the control unit according to the fourth superimposed signal, and controlling the first switch unit to be turned on according to the sixth drive signal, and driving the second switch unit to be turned off according to the sixth drive signal; When the seventh ambient temperature is greater than the sixth ambient temperature and reaches the standard test temperature: generating a seventh driving signal based on the control unit according to the fifth superimposed signal, and controlling the first switch unit and the second switch unit to be turned off according to the seventh driving signal; When the eighth ambient temperature is greater than the standard test temperature: The control unit generates an eighth driving signal according to the sixth superimposed signal, and controls the first switching unit and the second switching unit to be turned off according to the eighth driving signal.

16. The method for controlling the number of photovoltaic strings connected in series according to any one of claims 11 to 15, characterized in that: Based on the photovoltaic string series quantity adjustment control device according to claim 8, the method comprises: Based on the temperature monitoring unit, the ambient temperature of each photovoltaic string under the working condition is monitored to obtain multiple temperature signals; The output voltage signal of each photovoltaic string is collected based on the DC voltage collection unit; Based on the difference superposition unit, the output voltage signal of each photovoltaic string is subtracted from the preset voltage signal to obtain a plurality of first-type difference results, or while obtaining the first-type difference results, each output voltage signal is subtracted from the lowest output voltage signal to obtain a plurality of second-type difference results, and each first-type difference result is superimposed with each second-type difference result to obtain a plurality of superimposed signals; Based on the control unit generating a corresponding first control signal according to each first-type difference result, or generating a corresponding second control signal according to each superposition signal, and controlling the corresponding switch unit to be turned on or off according to the first control signal and the second control signal; When each switch unit is in the on state, the photovoltaic components connected in parallel therewith are short-circuited to reduce the number of series connections of the corresponding photovoltaic strings; wherein the photovoltaic components connected in parallel with each switch unit are adjusted for the corresponding number of strings.

Images