Photovoltaic power supply secondary distributed cooperative control method based on output power characteristic value mapping

Abstract

The invention discloses a photovoltaic power supply secondary distributed cooperative control method based on output power characteristic value mapping, and the method comprises the steps: guaranteeing the consistency control of the output voltage of each photovoltaic power supply based on a virtual leader-following node strategy, and calculating the voltage compensation amount [delta] v1; based on a pre-constructed control parameter and illumination intensity mapping table, calculating a power compensation amount delta v2 and calculating a reference voltage compensation value while controlling the proportion consistency of the output power of the photovoltaic power supply; correcting the reference voltage based on the reference voltage compensation value; and according to the corrected reference voltage value and the photovoltaic power supply output voltage, generating a power reference value through a PI controller, and adjusting a duty ratio signal of a DC / DC converter to realize dynamic distribution of photovoltaic output power. Aiming at the fair power distribution problem of a photovoltaic power supply under different illumination conditions, the invention provides a cooperative control method which gives consideration to the advantages of droop control and can simultaneously realize power balanced distribution under the same and different illumination conditions.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic control, and in particular to a secondary distributed collaborative control method for photovoltaic power sources based on output power eigenvalue mapping. Background Art

[0002] With the rapid development of photovoltaic power generation technology, the large-scale integration of distributed photovoltaic power sources has become a key development trend in new energy power systems. However, traditional photovoltaic integration methods rely primarily on maximum power point tracking (MPPT) control strategies, which means that photovoltaic output depends solely on local conditions and is difficult to coordinate with grid dispatch requirements. In DC microgrid scenarios, the MPPT mode can cause bus voltage fluctuations, affecting system stability.

[0003] Because existing PV power sources with DC droop control assume the same irradiance conditions for each PV source when designing their droop curves, when different PV sources are exposed to different lighting conditions, the existing droop control strategy causes each PV source to distribute power based on the droop relationship under the same lighting conditions, rather than balancing current according to their respective maximum available power. This approach can cause some PV sources to be overloaded while others are underutilized, leading to biased power distribution, unfair power generation, and even compromising the safe and stable operation of the system.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of this application. It does not necessarily belong to the prior art of this application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of this application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0005] The purpose of the present invention is to provide a secondary distributed cooperative control method for photovoltaic power sources that takes into account the different irradiance conditions of each photovoltaic power source and fully balances the power distribution of each photovoltaic power source.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A secondary distributed cooperative control method for photovoltaic power sources based on output power eigenvalue mapping, comprising:

[0008] Implementing voltage recovery in secondary coordinated control includes: ensuring consistent control of the output voltages of each photovoltaic power source based on a virtual leader-follower node strategy while calculating the voltage compensation Δv1;

[0009] Implementing power sharing in secondary coordinated control includes: calculating the ratio of the output power of each photovoltaic power source to the maximum available power based on a pre-built control parameter and light intensity mapping table; calculating the power compensation amount Δv2 while controlling the consistency of the output power ratio of the photovoltaic power sources;

[0010] Calculate the reference voltage compensation value Δv=Δv1+Δv2;

[0011] Correct the reference voltage based on the following formula: in, is the corrected reference voltage value, is the uncorrected reference voltage value, m is the droop coefficient, i l is the current value output to the DC bus;

[0012] According to the corrected reference voltage value and the output voltage of the photovoltaic power supply, a power reference value is generated through the PI controller, and the duty cycle signal of the DC / DC converter is adjusted to realize the dynamic distribution of the photovoltaic output power.

[0013] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the voltage recovery in the secondary coordinated control is achieved by:

[0014] One photovoltaic power source is defined as a virtual leader node, and the other photovoltaic power sources are defined as follower nodes;

[0015] The local output voltage of each photovoltaic power source is collected, and the error between the local output voltage of the i-th photovoltaic power source and the reference voltage configured by the virtual leader node is input into the PI controller. The sum of the differences between the local output voltage of the i-th photovoltaic power source and the output voltages of all adjacent nodes is calculated, and the voltage compensation amount Δv1 is calculated by the PI controller:

[0016]

[0017] Among them, v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the photovoltaic power source corresponding to all nodes adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the virtual leader node is preset to be v ref , coefficient d i =1 represents the virtual leader node, the coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K vi Calculate the integral coefficient of voltage compensation for the PI controller, N i is the number of neighboring nodes of the i-th photovoltaic power source.

[0018] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the power flow sharing in the secondary coordinated control is achieved by the following method:

[0019] The light sensor is used to detect the light intensity of each photovoltaic power source in real time, and the pre-built minimum power voltage derivative is used to calculate the light intensity of each photovoltaic power source. The mapping table of light intensity G is used to query the control parameters corresponding to the current light intensity;

[0020] The photovoltaic output power ratio is calculated using the following formula: Among them, β i is the output power ratio of the i-th photovoltaic power source, is the minimum power-voltage derivative obtained by mapping the light intensity of the i-th photovoltaic power source, is the control parameter obtained by mapping the light intensity of the photovoltaic power source corresponding to the virtual leader node, P i is the output power of the i-th photovoltaic power source, is the maximum available power of the i-th photovoltaic power source;

[0021] By fixing the period i It is transmitted to the adjacent photovoltaic power source, and the power compensation amount Δv2 is calculated by the PI controller:

[0022]

[0023] Among them, β j is the output power ratio of the photovoltaic power sources corresponding to all nodes adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculate the integral coefficient of power compensation for the PI controller, N i is the number of neighboring nodes of the i-th photovoltaic power source.

[0024] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the calculation formula for generating the power reference value through the PI controller is:

[0025]

[0026] in, is the power reference value of the photovoltaic power source, v dc is the DC bus voltage, K p Calculate the proportional coefficient of the power reference value for the PI controller, K i Calculates the integral coefficient of the power reference for the PI controller.

[0027] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the DC / DC converter is provided between the photovoltaic array and the DC bus, and the duty cycle signal of the DC / DC converter is adjusted by:

[0028] Collect the output voltage v of the photovoltaic array pv and the output current i pv , to calculate the output power of the photovoltaic array

[0029] calculate and The ratio of is used as the duty cycle of the DC / DC converter.

[0030] Furthermore, according to any one of the above technical solutions or a combination of multiple technical solutions, an inductor and a voltage loop are sequentially provided on the output side of the DC / DC converter, and the current at the voltage loop is collected as the current value i output to the DC bus. l .

[0031] Furthermore, according to any one of the aforementioned technical solutions or a combination of multiple technical solutions, each photovoltaic power source only exchanges information with one adjacent photovoltaic power source.

[0032] Furthermore, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the voltage compensation amount is calculated as follows: Δv1 = K vp [(v dc_i -v dc_j )+d i (v ref -v dc_i )]+K vi ∫[(v dc_i -v dc_j )+d i (v ref -v dc_i )]dt, where v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the only photovoltaic power source adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the preset virtual leader node is v ref , coefficient d i =1 represents the virtual leader node, the coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K vi Calculate the integral coefficient of voltage compensation for the PI controller;

[0033] The calculation formula of the power compensation amount is: Δv2=k*K bp *(β i-β j )+K bi *∫(β i -β j )dt, where β j is the output power ratio of the only photovoltaic power source adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculates the integral coefficient of the power compensation for the PI controller.

[0034] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the output voltages of adjacent photovoltaic power sources are exchanged within a fixed period during the voltage recovery process in the secondary coordinated control;

[0035] In the process of realizing power sharing in secondary coordinated control, the proportion of photovoltaic output power is transferred to adjacent photovoltaic power sources within a fixed period.

[0036] Furthermore, according to any one of the above technical solutions or a combination of multiple technical solutions, the calculation of the voltage compensation amount and the calculation of the power compensation amount both adopt a first fixed period;

[0037] The calculation of the corrected reference voltage and the power reference value both adopts a second fixed period, and the second fixed period is less than or equal to 1 percent of the first fixed period.

[0038] The beneficial effects brought about by the technical solution provided by the present invention are as follows:

[0039] a. To address the issue of fair power distribution for photovoltaic power sources under different lighting conditions, a collaborative control method is provided that takes into account the advantages of droop control and can simultaneously achieve balanced power distribution under the same and different lighting conditions, thereby improving the adaptability, stability, and usability of photovoltaic grid-connected systems.

[0040] b. By introducing an output voltage recovery mechanism based on a virtual leader-follower photovoltaic power source, the output voltage of each photovoltaic power source is restored while ensuring consistent control of the photovoltaic power source output voltage;

[0041] c. Combined with the power circuit control logic, the photovoltaic output power ratio is regularly transferred between adjacent photovoltaic power sources to achieve coordinated control of fair distribution of photovoltaic power under different lighting conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic diagram of a distributed photovoltaic architecture based on output power eigenvalue mapping provided by an exemplary embodiment of the present invention;

[0044] Figure 2 A schematic flow chart of a secondary distributed coordinated control method for photovoltaic power sources provided by an exemplary embodiment of the present invention;

[0045] Figure 3 A schematic diagram of flexible switching between a DC bus voltage regulation mode and an MPPT mode provided by an exemplary embodiment of the present invention;

[0046] Figure 4 A schematic diagram of photovoltaic output power ratio provided for an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0049] Under the traditional droop control strategy, the power distribution of photovoltaic power sources depends only on the droop coefficient, and fails to consider the actual power generation capacity of each photovoltaic power source. As a result, the power sharing ratio does not match the maximum available photovoltaic power under different light conditions, affecting power generation fairness and system stability.

[0050] In one embodiment of the present invention, a secondary distributed cooperative control method for photovoltaic power sources based on output power eigenvalue mapping is provided, which aims to solve the problem that distributed photovoltaic power sources in DC microgrids are difficult to achieve fair power distribution under different lighting conditions. Figure 1 As shown in the architecture diagram of distributed photovoltaic based on output power characteristic value mapping, the photovoltaic array of the photovoltaic power generation system is connected to the DC bus through a DC / DC converter. In a specific embodiment, the output side of the DC / DC converter is provided with an inductor and a voltage loop in sequence, and the current at the voltage loop is collected as the current value i output to the DC bus. l .

[0051] like Figure 2 As shown, the photovoltaic power supply secondary distributed coordinated control method includes the following steps:

[0052] The first step is to achieve voltage recovery in secondary coordinated control, including: based on the virtual leader-follower node strategy, ensuring the consistency of the output voltage of each photovoltaic power source while calculating the voltage compensation amount Δv1;

[0053] In a specific embodiment, one photovoltaic power source is defined as a virtual leader node, and the other photovoltaic power sources are defined as follower nodes;

[0054] The local output voltage of each photovoltaic power source is collected, and the error between the local output voltage of the i-th photovoltaic power source and the reference voltage configured by the virtual leader node is input into the PI controller. The sum of the differences between the local output voltage of the i-th photovoltaic power source and the output voltages of all adjacent nodes is calculated, and the voltage compensation amount Δv1 is calculated by the PI controller:

[0055]

[0056] Among them, v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the photovoltaic power source corresponding to all nodes adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the virtual leader node is preset to be v ref , coefficient d i =1 represents the virtual leader node, the coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K viCalculate the integral coefficient of voltage compensation for the PI controller, N i is the number of adjacent nodes of the ith photovoltaic power source. In this embodiment, the ith photovoltaic power source is defined as the photovoltaic power source corresponding to the virtual leader node.

[0057] The second step is to achieve power flow sharing in the secondary coordinated control, including: calculating the photovoltaic output power ratio of each photovoltaic power source to the maximum available power based on the pre-built control parameter and light intensity mapping table; while calculating the power compensation amount Δv2 based on the consistency control of the photovoltaic power source output power ratio;

[0058] In a specific embodiment, a light sensor is used to detect the light intensity of each photovoltaic power source in real time, and a pre-built minimum power voltage derivative is used. The mapping table between the control parameters and the light intensity G is used to query the control parameters corresponding to the current light intensity. In a specific embodiment, the pre-built control parameter and light intensity mapping table is shown in Table 1:

[0059] Table 1 Photovoltaic characteristic parameter mapping table

[0060]

[0061] The photovoltaic output power ratio β is defined as: β can approximately represent the output power ratio under a certain light intensity G, combined with Figure 4 Schematic diagram of photovoltaic output power ratio. For photovoltaic power sources with different installed capacities, the approximate ratio is:

[0062] Among them, β i is the output power ratio of the i-th photovoltaic power source, is the minimum power-voltage derivative obtained by mapping the light intensity of the i-th photovoltaic power source, is the control parameter obtained by mapping the light intensity of the photovoltaic power source corresponding to the virtual leader node, P i is the output power of the i-th photovoltaic power source, is the maximum available power of the i-th photovoltaic power source.

[0063] Figure 4 The four photovoltaic output power ratio curves correspond to light intensity 1000 / photovoltaic array series number 63, light intensity 800 / photovoltaic array series number 63, light intensity 1000 / photovoltaic array series number 84, and light intensity 800 / photovoltaic array series number 84 respectively.

[0064] By fixing the period i It is transmitted to the adjacent photovoltaic power source, and the power compensation amount Δv2 is calculated by the PI controller:

[0065]

[0066] Among them, β j is the output power ratio of the photovoltaic power sources corresponding to all nodes adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculate the integral coefficient of power compensation for the PI controller, N i is the number of neighboring nodes of the i-th photovoltaic power source.

[0067] Step 3: Calculate the reference voltage compensation value Δv=Δv1+Δv2; and the present invention does not limit the execution order of the first and second steps.

[0068] Step 4: Correct the reference voltage based on the following formula: in, is the corrected reference voltage value, is the uncorrected reference voltage value, m is the droop coefficient, i l is the current value output to the DC bus;

[0069] Step 5: Based on the corrected reference voltage value and the output voltage of the photovoltaic power supply, a power reference value is generated through the PI controller, and the duty cycle signal of the DC / DC converter is adjusted to achieve dynamic distribution of the photovoltaic output power.

[0070] Specifically, the calculation formula for generating the power reference value through the PI controller is:

[0071]

[0072] in, is the power reference value of the photovoltaic power source, v dc is the DC bus voltage, K p Calculate the proportional coefficient of the power reference value for the PI controller, K i Calculates the integral coefficient of the power reference for the PI controller.

[0073] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the DC / DC converter is provided between the photovoltaic array and the DC bus, and the duty cycle signal of the DC / DC converter is adjusted by:

[0074] Collect the output voltage v of the photovoltaic array pv and the output current i pv , to calculate the output power of the photovoltaic array

[0075] calculate and The ratio of is used as the duty cycle of the DC / DC converter.

[0076] In a specific embodiment of the present invention, each photovoltaic power source only exchanges information with one adjacent photovoltaic power source, and multiple photovoltaic power sources are linked in a ring unidirectional manner, which can not only meet the basic requirements of distributed communication but also avoid complex communication networks and information iterative calculations.

[0077] In the embodiment where there is only one adjacent photovoltaic power source, N i Substituting 1 into the above formula, we can get the simplified calculation formula of voltage compensation: Δv1=K vp [(v dc_i -v dc_j )+d i (v ref -v dc_i )]+K vi ∫[(v dc_i -v dc_j )+d i (v ref -v dc_i )]dt, where v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the only photovoltaic power source adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the preset virtual leader node is v ref , coefficient d i =1 represents the virtual leader node, the coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K vi Calculate the integral coefficient of voltage compensation for the PI controller;

[0078] And the simplified calculation formula of power compensation: Δv2=k*K bp *(β i -β j )+K bi *∫(β i -β j )dt, where β j is the output power ratio of the only photovoltaic power source adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculates the integral coefficient of the power compensation for the PI controller.

[0079] Furthermore, fixed-period data acquisition and control triggering not only reduce communication frequency and real-time requirements, but also reduce the system's computational burden: during voltage recovery in secondary coordinated control, the output voltages of adjacent photovoltaic power sources are exchanged within a fixed period; during power current sharing in secondary coordinated control, the photovoltaic output power ratio is transmitted to adjacent photovoltaic power sources within a fixed period. In a specific embodiment, the voltage compensation amount and the power compensation amount are both calculated using a first fixed period, such as calculating the voltage compensation amount and calculating the power compensation amount every 50ms; while the corrected reference voltage and power reference value are both calculated using a second fixed period, which is less than or equal to one percent of the first fixed period, such as dynamically allocating power to distributed photovoltaics every 0.25ms.

[0080] Combine Figure 3 As shown in the figure, under different load levels, the photovoltaic power supply can flexibly switch operating modes according to system requirements. When the system load is less than the maximum power generation capacity of the photovoltaic power supply, the photovoltaic power supply prioritizes adjusting the output power to maintain DC bus voltage stability, and operates in DC bus regulation mode. When the load increases and exceeds the maximum power generation capacity of the photovoltaic power supply, the photovoltaic power supply can no longer provide additional voltage support and therefore enters MPPT mode (maximum power point tracking mode) to maximize its own power generation utilization. This mode switching mechanism ensures that the photovoltaic power supply can balance bus voltage stability and power generation efficiency under different load conditions, thereby improving the flexibility and adaptability of system operation.

[0081] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0082] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A photovoltaic power supply secondary distributed collaborative control method based on output power eigenvalue mapping, characterized in that: include: Implementing voltage recovery in secondary coordinated control includes: ensuring consistent control of the output voltages of each photovoltaic power source based on a virtual leader-follower node strategy while calculating the voltage compensation Δv1; Implementing power sharing in secondary coordinated control includes: calculating the ratio of the output power of each photovoltaic power source to the maximum available power based on a pre-built control parameter and light intensity mapping table; calculating the power compensation amount Δv2 while controlling the consistency of the output power ratio of the photovoltaic power sources; Calculate the reference voltage compensation value Δv=Δv1+Δv2; Correct the reference voltage based on the following formula: in, is the corrected reference voltage value, is the uncorrected reference voltage value, m is the droop coefficient, i l is the current value output to the DC bus; According to the corrected reference voltage value and the output voltage of the photovoltaic power supply, a power reference value is generated through the PI controller, and the duty cycle signal of the DC / DC converter is adjusted to realize the dynamic distribution of the photovoltaic output power.

2. The photovoltaic power secondary distributed coordinated control method according to claim 1, characterized in that: The voltage recovery in the secondary coordinated control is achieved by: One photovoltaic power source is defined as a virtual leader node, and the other photovoltaic power sources are defined as follower nodes; The local output voltage of each photovoltaic power source is collected, and the error between the local output voltage of the i-th photovoltaic power source and the reference voltage configured by the virtual leader node is input into the PI controller. The sum of the differences between the local output voltage of the i-th photovoltaic power source and the output voltages of all adjacent nodes is calculated, and the voltage compensation amount Δv1 is calculated by the PI controller: Among them, v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the photovoltaic power source corresponding to all nodes adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the virtual leader node is preset to be v ref , coefficient d i =1 represents the virtual leader node, coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K vi Calculate the integral coefficient of voltage compensation for the PI controller, N i is the number of neighboring nodes of the i-th photovoltaic power source.

3. The photovoltaic power secondary distributed coordinated control method according to claim 1, characterized in that: The power flow sharing in the secondary coordinated control is achieved by the following methods: The light sensor is used to detect the light intensity of each photovoltaic power source in real time, and the pre-built minimum power voltage derivative is used to calculate the light intensity of each photovoltaic power source. The mapping table of light intensity G is used to query the control parameters corresponding to the current light intensity; The photovoltaic output power ratio is calculated using the following formula: Among them, β i is the output power ratio of the i-th photovoltaic power source, is the minimum power-voltage derivative obtained by mapping the light intensity of the i-th photovoltaic power source, is the control parameter obtained by mapping the light intensity of the photovoltaic power source corresponding to the virtual leader node, P i is the output power of the i-th photovoltaic power source, is the maximum available power of the i-th photovoltaic power source; By fixing the period β i It is transmitted to the adjacent photovoltaic power source, and the power compensation amount Δv2 is calculated by the PI controller: Among them, β j is the output power ratio of the photovoltaic power sources corresponding to all nodes adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculate the integral coefficient of power compensation for the PI controller, N i is the number of neighboring nodes of the i-th photovoltaic power source.

4. The photovoltaic power secondary distributed coordinated control method according to claim 1, characterized in that: The calculation formula for generating the power reference value through the PI controller is: in, is the power reference value of the photovoltaic power source, v dc is the DC bus voltage, K p Calculate the proportional coefficient of the power reference value for the PI controller, K i Calculates the integral coefficient of the power reference for the PI controller.

5. The photovoltaic power secondary distributed coordinated control method according to claim 4, characterized in that: The DC / DC converter is arranged between the photovoltaic array and the DC bus, and the duty cycle signal of the DC / DC converter is adjusted in the following manner: Collect the output voltage v of the photovoltaic array pv and the output current i pv , to calculate the output power of the photovoltaic array calculate and The ratio of is used as the duty cycle of the DC / DC converter.

6. The photovoltaic power secondary distributed coordinated control method according to claim 1, characterized in that: The output side of the DC / DC converter is provided with an inductor and a voltage loop in sequence, and the current at the voltage loop is collected as the current value i output to the DC bus. l .

7. The photovoltaic power secondary distributed coordinated control method according to claim 1, characterized in that: Each photovoltaic power source only exchanges information with one adjacent photovoltaic power source.

8. The photovoltaic power secondary distributed coordinated control method according to claim 7, characterized in that: The calculation formula of the voltage compensation amount is: Δv1=K vp [(v dc_i -v dc_j )+d i (v ref -v dc_i )]+K vi ∫[(v dc_i -v dc_j )+d i (v ref -v dc_i )]dt, where v dc_i is the local output voltage of the i-th photovoltaic power source, v dc_j is the local output voltage of the only photovoltaic power source adjacent to the i-th photovoltaic power source, and the reference voltage of the photovoltaic power source corresponding to the preset virtual leader node is v ref , coefficient d i =1 represents the virtual leader node, coefficient d i =0 represents the following node, K vp Calculate the proportional coefficient of voltage compensation for the PI controller, K vi Calculate the integral coefficient of voltage compensation for the PI controller; The calculation formula of the power compensation amount is: Δv2=k*K bp *(β i -β j )+K bi *∫(β i -β j )dt, where β j is the output power ratio of the only photovoltaic power source adjacent to the i-th photovoltaic power source, k is the preset amplification factor, K bp Calculate the proportional coefficient of power compensation for the PI controller, K bi Calculates the integral coefficient of the power compensation for the PI controller.

9. The photovoltaic power supply secondary distributed coordinated control method according to claim 1, characterized in that: To achieve voltage recovery in secondary coordinated control, the output voltages of adjacent photovoltaic power sources are exchanged within a fixed period; In the process of realizing power sharing in secondary coordinated control, the proportion of photovoltaic output power is transferred to adjacent photovoltaic power sources within a fixed period.

10. The photovoltaic power supply secondary distributed coordinated control method according to claim 9, characterized in that: The calculation of voltage compensation amount and the calculation of power compensation amount both adopt the first fixed period; The calculation of the corrected reference voltage and the power reference value both adopts a second fixed period, and the second fixed period is less than or equal to 1 percent of the first fixed period.

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