A photovoltaic grid-connected power generation system and method

Abstract

The application discloses a kind of photovoltaic grid-connected power generation system and method, the system includes photovoltaic array, photovoltaic junction box, photovoltaic DC cabinet and photovoltaic inverter;The photovoltaic array converts light energy into electric energy output photovoltaic DC power, in turn after the photovoltaic junction box, the photovoltaic DC cabinet and the photovoltaic inverter with grid-connected;By the control module in photovoltaic junction box control current equalizer in photovoltaic junction box to the photovoltaic DC power of each photovoltaic PV group string output in photovoltaic array carries out equalization current distribution, and the photovoltaic DC power after equalization current distribution is summarized to MPPT module in photovoltaic junction box, by MPPT module output the confluence DC power when the maximum power of photovoltaic array, solve environmental factor to the influence of photovoltaic DC power and lead to the current loss of photovoltaic power generation, reduce the current loss of photovoltaic power generation, to improve the stability of photovoltaic grid-connected power generation.

Description

Technical Field

[0001] This invention relates to the field of grid-connected photovoltaic power generation, and more particularly to a grid-connected photovoltaic power generation system and method. Background Technology

[0002] Photovoltaic power generation, as an important clean energy source, has experienced rapid development in recent years. However, the output of photovoltaic cells fluctuates and is intermittent due to variations in sunlight intensity and temperature. Therefore, the grid-connected operation of large-scale photovoltaic power generation systems can significantly impact the stability of the traditional power grid. In a photovoltaic power generation system, photovoltaic modules convert sunlight into direct current (DC), which is then electrically connected via combiner boxes and distribution cabinets. Photovoltaic inverters convert this randomly varying DC power into alternating current (AC) with the same frequency and phase as the public power grid, thus achieving grid-connected photovoltaic power generation.

[0003] In existing photovoltaic power generation systems, the traditional combiner box only aggregates the DC power output from several photovoltaic modules, ignoring the impact of environmental factors on DC power. This leads to current loss in photovoltaic power generation, resulting in low stability of grid-connected photovoltaic power generation. Summary of the Invention

[0004] This invention solves the problem of current loss in photovoltaic power generation caused by the influence of environmental factors on photovoltaic DC power, thereby reducing the current loss in photovoltaic power generation and improving the stability of photovoltaic grid-connected power generation.

[0005] To address the aforementioned technical problems, one embodiment of the present invention provides a photovoltaic grid-connected power generation system, comprising: a photovoltaic array, a photovoltaic combiner box, a photovoltaic DC cabinet, and a photovoltaic inverter; the photovoltaic array is composed of several photovoltaic PV strings; the photovoltaic combiner box includes: a control module, a current equalizer, and an MPPT module;

[0006] The photovoltaic array is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic inverter;

[0007] The photovoltaic (PV) strings in the photovoltaic array convert light energy into electrical energy and output photovoltaic DC power to the photovoltaic combiner box.

[0008] The photovoltaic combiner box is used to control the current equalizer through the control module to distribute the photovoltaic DC power transmitted by each photovoltaic PV string in a balanced manner, and to collect the photovoltaic DC power after the balanced current distribution to the MPPT module, and then output the combiner DC power of the photovoltaic array at maximum power to the photovoltaic DC cabinet through the MPPT module.

[0009] The photovoltaic DC cabinet is used to process the combined DC power output from the photovoltaic combiner box and output the processed photovoltaic DC power.

[0010] The photovoltaic inverter is used to invert the processed photovoltaic DC power output from the photovoltaic DC cabinet to obtain photovoltaic AC power, and then input the photovoltaic AC power to the grid connection point for grid connection processing.

[0011] Furthermore, each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the PV DC output formula for each PV panel is as follows:

[0012]

[0013] In the formula, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; I m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

[0014] Furthermore, the corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel are calculated using the following formulas.

[0015]

[0016] In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. oc I represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel.

[0017] Furthermore, the step of controlling the current equalizer via the control module to perform equal current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string includes:

[0018] The control module employs a perfect balance control strategy to control the current equalizer to distribute the photovoltaic DC power transmitted by each photovoltaic PV string in a balanced manner; the control module includes a PI controller and a PWM controller; the control equation of the perfect balance control strategy is:

[0019]

[0020] In the formula, I g Vg is the photovoltaic DC power after equalization current distribution; K is the combiner box voltage; p and T is These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i represents the equalizing current; n represents the turns ratio of the primary and secondary coils of the current equalizer; L represents the inductance of the current equalizer; C represents the capacitance of the current equalizer; s represents the Laplace operator; R represents the resistance of the current equalizer.

[0021] Based on the above system implementation examples, the present invention provides corresponding method implementation examples;

[0022] An embodiment of the present invention provides a photovoltaic grid-connected power generation method, applicable to photovoltaic grid-connected power generation systems, comprising:

[0023] The photovoltaic array converts solar energy into electrical energy through photovoltaic (PV) strings, outputting photovoltaic direct current.

[0024] The control module of the photovoltaic combiner box controls the current equalizer to distribute the photovoltaic DC power equally, and then the photovoltaic DC power after equalization is collected to the MPPT module of the photovoltaic combiner box. Then, the MPPT module of the photovoltaic combiner box outputs the combined DC power when the photovoltaic array is at its maximum power.

[0025] The combined DC power is processed by a photovoltaic DC switch, and the processed photovoltaic DC power is output.

[0026] The processed photovoltaic DC power is inverted by a photovoltaic inverter to obtain photovoltaic AC power, which is then input to the grid connection point for grid connection.

[0027] Furthermore, each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the PV DC output formula for each PV panel is as follows:

[0028]

[0029] In the formula, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; I m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

[0030] Furthermore, the actual light intensity and ambient temperature are obtained, and the corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel are calculated using the following formulas.

[0031]

[0032] In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. oc I represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel.

[0033] Furthermore, the step of controlling the current equalizer to perform equal current distribution of photovoltaic DC power through the control module in the photovoltaic combiner box includes:

[0034] The control module employs a perfect balance control strategy to control the current equalizer to distribute the photovoltaic DC power transmitted by each photovoltaic PV string in a balanced manner; the control module includes a PI controller and a PWM controller; the control equation of the perfect balance control strategy is:

[0035]

[0036] In the formula, I g Vg is the photovoltaic DC power after equalization current distribution; K is the combiner box voltage; p and T is These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i represents the equalizing current; n represents the turns ratio of the primary and secondary coils of the current equalizer; L represents the inductance of the current equalizer; C represents the capacitance of the current equalizer; s represents the Laplace operator; R represents the resistance of the current equalizer.

[0037] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0038] This invention first uses the control module of the photovoltaic combiner box to control the current equalizer to distribute the photovoltaic DC power transmitted by each photovoltaic (PV) string in a balanced manner. The balanced photovoltaic DC power is then aggregated to the MPPT module, which then outputs the combined DC power at maximum power of the PV strings. In other words, by distributing the balanced current to the photovoltaic DC power transmitted by each PV string, this invention compensates for the current loss caused by environmental factors affecting the photovoltaic DC power, thereby reducing the current loss of photovoltaic power generation and improving the stability of grid-connected photovoltaic power generation. Attached Figure Description

[0039] Figure 1 : A structural diagram of a photovoltaic grid-connected power generation system provided in an embodiment of the present invention;

[0040] Figure 2 : A flowchart of a photovoltaic grid-connected power generation method provided in an embodiment of the present invention;

[0041] Figure 3 : A simulation model diagram of a single photovoltaic (PV) string and a current equalizer provided in an embodiment of the present invention;

[0042] Figure 4 : A simulation model diagram of the combination of photovoltaic (PV) strings and photovoltaic combiner boxes provided in an embodiment of the present invention;

[0043] Figure labeling: 1. Current equalizer; 2. Control module; 3. Photovoltaic array, PV1, PV2 and PV3 represent photovoltaic PV strings; 4. MPPT module. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1:

[0046] Please refer to Figure 1 and Figure 4 , Figure 1 This is a structural diagram of a photovoltaic grid-connected power generation system provided in an embodiment of the present invention. Figure 4 This is a simulation model diagram of a photovoltaic (PV) string and a photovoltaic combiner box provided in an embodiment of the present invention. The system includes: a photovoltaic array 3, a photovoltaic combiner box, a photovoltaic DC cabinet, and a photovoltaic inverter; the photovoltaic array 3 is composed of several photovoltaic PV strings; the photovoltaic combiner box includes: a control module 2, a current equalizer 1, and an MPPT module 4;

[0047] The photovoltaic array 3 is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic inverter;

[0048] The photovoltaic (PV) strings in the photovoltaic array 3 convert light energy into electrical energy and output photovoltaic DC power to the photovoltaic combiner box.

[0049] The photovoltaic combiner box is used to control the current equalizer 1 through the control module 2 to perform equal current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string, and to collect the equal current distributed photovoltaic DC power to the MPPT module 4, and then output the combiner DC power of the photovoltaic array 3 at maximum power to the photovoltaic DC cabinet through the MPPT module 4.

[0050] In this embodiment, refer to Figure 3 and Figure 4 Several current equalizers 1 are connected one by one to several photovoltaic (PV) strings in the photovoltaic array 3. The current equalizers 1 perform equalization current distribution on the photovoltaic DC power transmitted by the PV strings. The control module 2 controls each current equalizer 1 to perform equalization current distribution on the photovoltaic DC power transmitted by each PV string. The equalized photovoltaic DC power is then collected and sent to the MPPT module 4. The MPPT module 4 then outputs the bus DC power at maximum power of the photovoltaic array 3 to the photovoltaic DC cabinet. The control module 2 includes a PI controller and a PWM controller.

[0051] The photovoltaic DC cabinet is used to process the combined DC power output from the photovoltaic combiner box and output the processed photovoltaic DC power.

[0052] In this embodiment, the photovoltaic DC cabinet processes the combined DC power output from several photovoltaic combiner boxes. This processing includes allocation, monitoring, and protection. Allocation includes, but is not limited to, distributing the combined DC power from the photovoltaic combiner boxes to different loads or energy storage systems via DC circuit breakers or contactors, and distributing the combined DC power from the photovoltaic combiner boxes to photovoltaic inverters via combiner buses. Monitoring involves real-time monitoring of parameters of the combined DC power output from the photovoltaic combiner boxes using an integrated monitoring module or system. These parameters include voltage, current, and power, etc., and the photovoltaic system's operating status is analyzed for power generation efficiency and fault warning based on the monitored parameters through a central control system or remote monitoring platform. Protection includes, but is not limited to, overload protection, short-circuit protection, overvoltage protection, and lightning protection.

[0053] The photovoltaic inverter is used to invert the processed photovoltaic DC power output from the photovoltaic DC cabinet to obtain photovoltaic AC power, and then input the photovoltaic AC power to the grid connection point for grid connection processing.

[0054] In this embodiment, the photovoltaic inverter includes, but is not limited to, a two-stage photovoltaic inverter, which consists of a boost circuit, a bridge inverter circuit, and a filter circuit. The boost circuit is used to boost the voltage of the photovoltaic DC power output from the photovoltaic DC cabinet. The bridge inverter circuit converts the boosted photovoltaic DC power into photovoltaic AC power. The filter circuit smooths and filters the photovoltaic AC power. The bridge inverter circuit includes, but is not limited to, full-bridge inverter circuits, half-bridge inverter circuits, single-phase bridge inverter circuits, three-phase bridge inverter circuits, and push-pull inverter circuits.

[0055] In this embodiment, the photovoltaic AC power is input to the grid connection point for grid connection processing, including:

[0056] When the photovoltaic AC power is single-phase, it is connected to the single-phase power grid; when the photovoltaic AC power is three-phase, it is connected to the three-phase power grid.

[0057] In this embodiment, each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the photovoltaic DC power output formula for each PV panel is as follows:

[0058]

[0059] x middle, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; I m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

[0060] In this embodiment, the corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel are calculated using the following formulas.

[0061]

[0062] In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. ocI represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel; t ref =25℃, S ref =1000W / m 2 a = 0.0025℃ -1 b = 0.5; c = 0.00288℃ -1 .

[0063] In this embodiment, the step of controlling the current equalizer 1 via the control module 2 to perform equal current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string includes:

[0064] The control module 2 employs a perfect balance control strategy to control the current equalizer 1 to perform balanced current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string; wherein, the control module 2 includes a PI controller and a PWM controller; the control equation of the perfect balance control strategy is:

[0065]

[0066] In the formula, I g Vg is the photovoltaic DC power after equalization current distribution; K is the combiner box voltage; p and T is These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i represents the equalization current; n represents the turns ratio of the primary and secondary coils of current equalizer 1; L represents the inductance of current equalizer 1; C represents the capacitance of current equalizer 1; s represents the Laplace operator; R represents the resistance of current equalizer 1.

[0067] Example 2:

[0068] Please refer to Figure 2 The above is a flowchart of a photovoltaic grid-connected power generation method provided by an embodiment of the present invention. The method is applicable to photovoltaic grid-connected power generation systems and includes at least the following steps:

[0069] Step S1: The photovoltaic (PV) strings in the photovoltaic array 3 convert light energy into electrical energy and output photovoltaic DC power.

[0070] In this embodiment, the photovoltaic array 3 is composed of several photovoltaic (PV) strings.

[0071] Step S2: The control module 2 of the photovoltaic combiner box controls the current equalizer 1 to perform equal current distribution on the photovoltaic DC power, and the equal current distribution photovoltaic DC power is collected to the MPPT module 4 of the photovoltaic combiner box, and then the combined DC power of the photovoltaic array 3 at maximum power is output through the MPPT module 4 of the photovoltaic combiner box.

[0072] In this embodiment, the photovoltaic combiner box includes: a control module 2, a current equalizer 1, and an MPPT module 4;

[0073] Step S3: Process the combined DC power through the photovoltaic DC cabinet and output the processed photovoltaic DC power;

[0074] In this embodiment, the photovoltaic DC cabinet processes the combined DC power output from several photovoltaic combiner boxes. This processing includes allocation, monitoring, and protection. Allocation includes, but is not limited to, distributing the combined DC power from the photovoltaic combiner boxes to different loads or energy storage systems via DC circuit breakers or contactors, and distributing the combined DC power from the photovoltaic combiner boxes to photovoltaic inverters via combiner buses. Monitoring involves real-time monitoring of parameters of the combined DC power output from the photovoltaic combiner boxes using an integrated monitoring module or system. These parameters include voltage, current, and power, etc., and the photovoltaic system's operating status is analyzed for power generation efficiency and fault warning based on the monitored parameters through a central control system or remote monitoring platform. Protection includes, but is not limited to, overload protection, short-circuit protection, overvoltage protection, and lightning protection.

[0075] Step S4: The processed photovoltaic DC power is inverted using a photovoltaic inverter to obtain photovoltaic AC power, which is then input to the grid connection point for grid connection.

[0076] In this embodiment, the photovoltaic inverter includes, but is not limited to, a two-stage photovoltaic inverter, which consists of a boost circuit, a bridge inverter circuit, and a filter circuit. The boost circuit is used to boost the voltage of the photovoltaic DC power output from the photovoltaic DC cabinet. The bridge inverter circuit converts the boosted photovoltaic DC power into photovoltaic AC power. The filter circuit smooths and filters the photovoltaic AC power. The bridge inverter circuit includes, but is not limited to, full-bridge inverter circuits, half-bridge inverter circuits, single-phase bridge inverter circuits, three-phase bridge inverter circuits, and push-pull inverter circuits.

[0077] In this embodiment, the photovoltaic AC power is input to the grid connection point for grid connection processing, including:

[0078] When the photovoltaic AC power is single-phase, it is connected to the single-phase power grid; when the photovoltaic AC power is three-phase, it is connected to the three-phase power grid.

[0079] In this embodiment, each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the photovoltaic DC power output formula for each PV panel is as follows:

[0080]

[0081] In the formula, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; I m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

[0082] In this embodiment, the actual light intensity and ambient temperature are obtained by a photosensitive sensor and a temperature sensor, and the corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel are calculated by the following formulas.

[0083]

[0084] In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. oc I represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel; t ref =25℃, S ref =1000W / m 2 a = 0.0025℃ -1 b = 0.5; c = 0.00288℃ -1 .

[0085] In this embodiment, the step of controlling the current equalizer 1 through the control module 2 in the photovoltaic combiner box to perform equal current distribution of photovoltaic DC power includes:

[0086] The control module 2 employs a perfect balance control strategy to control the current equalizer 1 to perform balanced current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string; wherein, the control module 2 includes a PI controller and a PWM controller; the control equation of the perfect balance control strategy is:

[0087]

[0088] In the formula, I g Vg is the photovoltaic DC power after equalization current distribution; K is the combiner box voltage; p and T is These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i represents the equalization current; n represents the turns ratio of the primary and secondary coils of current equalizer 1; L represents the inductance of current equalizer 1; C represents the capacitance of current equalizer 1; s represents the Laplace operator; R represents the resistance of current equalizer 1.

[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A photovoltaic grid-connected power generation system, characterized in that, include: The photovoltaic array comprises a photovoltaic combiner box, a photovoltaic DC cabinet, and a photovoltaic inverter; the photovoltaic array consists of several photovoltaic PV strings; the photovoltaic combiner box includes a control module, a current equalizer, and an MPPT module. The photovoltaic array is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic combiner box; the photovoltaic DC cabinet is connected to the photovoltaic inverter; The photovoltaic (PV) strings in the photovoltaic array convert light energy into electrical energy and output photovoltaic DC power to the photovoltaic combiner box. The photovoltaic combiner box is used to control the current equalizer via the control module to perform equalization current distribution on the photovoltaic DC power transmitted by each photovoltaic (PV) string, and then aggregates the equalized photovoltaic DC power to the MPPT module. The MPPT module then outputs the combiner DC power at maximum power of the photovoltaic array to the photovoltaic DC cabinet. The control module employs a perfect equalization control strategy to control the current equalizer to perform equalization current distribution on the photovoltaic DC power transmitted by each PV string. The control module includes a PI controller and a PWM controller. The control equation for the perfect equalization control strategy is: In the formula, I g The photovoltaic DC power is distributed in a balanced manner; Vg is the combiner box voltage; K p and T iS These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i s represents the equalization current; n represents the turns ratio of the primary and secondary coils of the current equalizer; L represents the inductance of the current equalizer; C represents the capacitance of the current equalizer; s represents the Laplace operator; R represents the resistance of the current equalizer. The photovoltaic DC cabinet is used to process the combined DC power output from the photovoltaic combiner box and output the processed photovoltaic DC power. The photovoltaic inverter is used to invert the processed photovoltaic DC power output from the photovoltaic DC cabinet to obtain photovoltaic AC power, and then input the photovoltaic AC power to the grid connection point for grid connection processing.

2. The photovoltaic grid-connected power generation system according to claim 1, characterized in that, Each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the PV DC output formula for each PV panel is as follows: In the formula, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; U m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

3. A photovoltaic grid-connected power generation system according to claim 2, characterized in that, The corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel are calculated using the following formulas. In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. oc I represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel.

4. A photovoltaic grid-connected power generation method, applicable to photovoltaic grid-connected power generation systems, characterized in that, include: The photovoltaic array converts solar energy into electrical energy through photovoltaic (PV) strings, outputting photovoltaic direct current. The control module of the photovoltaic combiner box controls the current equalizer to perform equal current distribution on the photovoltaic DC power, and then aggregates the equalized photovoltaic DC power to the MPPT module of the photovoltaic combiner box. The MPPT module then outputs the combined DC power at maximum power of the photovoltaic array. The control module employs a perfect equalization control strategy to control the current equalizer to perform equal current distribution on the photovoltaic DC power transmitted by each photovoltaic PV string. The control module includes a PI controller and a PWM controller. The control equation for the perfect equalization control strategy is as follows: In the formula, I g The photovoltaic DC power after equalization current distribution; V g The combiner box voltage; K p and T iS These represent the proportional and integral control coefficients of the PI controller, respectively; I ref Indicates the reference current; Ie i s represents the equalization current; n represents the turns ratio of the primary and secondary coils of the current equalizer; L represents the inductance of the current equalizer; C represents the capacitance of the current equalizer; s represents the Laplace operator; R represents the resistance of the current equalizer. The combined DC power is processed by a photovoltaic DC cabinet, and the processed photovoltaic DC power is output. The processed photovoltaic DC power is inverted by a photovoltaic inverter to obtain photovoltaic AC power, which is then input to the grid connection point for grid connection.

5. A photovoltaic grid-connected power generation method according to claim 4, characterized in that, Each photovoltaic (PV) string consists of several photovoltaic (PV) panels, and the PV DC output formula for each PV panel is as follows: In the formula, I sh ′ represents the corrected short-circuit current of the photovoltaic panel; U oc ′ represents the corrected open-circuit voltage of the photovoltaic panel; I m ′ represents the corrected maximum power point current of the photovoltaic panel; U m ′ represents the corrected maximum power point voltage of the photovoltaic panel; U represents the photovoltaic voltage output by the photovoltaic panel; and I represents the photovoltaic DC power output by the photovoltaic panel.

6. A photovoltaic grid-connected power generation method according to claim 5, characterized in that, include: Obtain the actual light intensity and ambient temperature, and calculate the corrected short-circuit current, corrected open-circuit voltage, corrected maximum power point current, and corrected maximum power point voltage of the photovoltaic panel using the following formulas; In the formula, t ref and S ref t and S represent the ambient temperature and light intensity under standard conditions, respectively; a, b, and c represent the ambient temperature and light intensity under actual conditions, respectively; I represents the photovoltaic compensation coefficients. sh U represents the uncorrected short-circuit current of the photovoltaic panel. oc I represents the uncorrected open-circuit voltage of the photovoltaic panel. m U represents the uncorrected maximum power point current of the photovoltaic panel. m This indicates the uncorrected maximum power point voltage of the photovoltaic panel.

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