Frequency modulation device, photovoltaic power station and photovoltaic system

Abstract

A frequency modulation device, a photovoltaic power station, and a photovoltaic system are disclosed. The frequency modulation device includes a power control module, a main switch, multiple sub-switches, and multiple monitoring modules. The power control module is used to connect to the grid at the grid connection point to obtain the voltage and current of the grid connection point. The main switch is connected to the power control module and the multiple sub-switches via optical fiber communication. The multiple monitoring modules are connected to the multiple sub-switches via optical fiber communication and are configured to correspond to multiple power generation units. Each monitoring module is used to connect to multiple string inverters of the corresponding power generation unit. The power control module is used to obtain the active power of the multiple string inverters sequentially through the multiple monitoring modules, multiple sub-switches, and the main switch. It is also used to output power adjustment commands to the multiple string inverters according to the voltage and current of the grid connection point and the active power of the multiple string inverters, thereby reducing the delay in the frequency modulation device receiving the active power of the string inverters.

Description

Technical Field

[0001] This utility model relates to the field of new energy frequency regulation, specifically to a frequency regulation device, a photovoltaic power station, and a photovoltaic system. Background Technology

[0002] String inverters have become the mainstream technology for centralized photovoltaic (PV) power plants due to their superior economic efficiency, flexible configuration, and higher power generation efficiency. Currently, PV power plants using string inverters generally employ a multi-layered communication architecture of "carrier + fiber," resulting in a significant delay of over 5 seconds in the power plant's acquisition of real-time inverter power information. This delay fails to meet the national standard requirements for rapid response time in primary frequency regulation (start-up <1s, response <5s), causing the power plant's frequency regulation based on lagging data to frequently erroneous. This not only fails to support grid stability but also amplifies power fluctuations and may even trigger grid oscillations, becoming a technical bottleneck restricting PV power plants from becoming a truly grid-friendly power source. Utility Model Content

[0003] The purpose of this invention is to provide a frequency modulation device, a photovoltaic power station, and a photovoltaic system to solve the problem of excessive delay in obtaining real-time power information from the inverter.

[0004] To achieve the objectives of this utility model, the following technical solution is provided:

[0005] In a first aspect, this utility model provides a frequency regulation device for a photovoltaic power station. The photovoltaic power station includes a photovoltaic array, which includes multiple power generation units. Each power generation unit includes multiple string inverters. The frequency regulation device includes: a power control module for connecting to the grid at a grid connection point to obtain the voltage and current of the grid connection point; a main switch for fiber optic communication connection to the power control module; multiple sub-switches for fiber optic communication connection to the main switch; and multiple monitoring modules for fiber optic communication connection to each of the sub-switches and for correspondingly setting up each of the multiple power generation units. Each monitoring module is electrically connected to multiple string inverters of the corresponding power generation unit. The power control module is used to obtain the active power of the multiple string inverters sequentially through the multiple monitoring modules, the multiple sub-switches, and the main switch. The power control module is also used to output power regulation commands to the multiple string inverters according to the voltage and current of the grid connection point and the active power of the multiple string inverters.

[0006] In one embodiment, each monitoring module includes multiple measurement and control units, each of which is optically connected to a corresponding sub-switch. The multiple measurement and control units are used to electrically connect one-to-one with multiple string inverters of the corresponding power generation unit, and the measurement and control units are used to collect the active power of the string inverters.

[0007] In one embodiment, each monitoring module further includes multiple adjustment units, each of which is optically connected to a corresponding sub-switch. The multiple adjustment units are used to be electrically connected one-to-one with multiple string inverters of the corresponding power generation unit, and the adjustment units are used to output the power adjustment command to the corresponding string inverter.

[0008] In one embodiment, the frequency modulation device further includes a voltage acquisition module and a current acquisition module. Both the voltage acquisition module and the current acquisition module are electrically connected to the power control module and are both used to be electrically connected to the grid connection point. The voltage acquisition module is used to acquire the voltage of the grid connection point, and the current acquisition module is used to acquire the current of the grid connection point.

[0009] In one embodiment, the voltage acquisition module includes a first voltage transformer, a second voltage transformer, and a third voltage transformer. All three voltage transformers are electrically connected to the power control module and are used to connect one-to-one with the three-phase lines at the grid connection point. The current acquisition module includes a first current transformer, a second current transformer, and a third current transformer. All three voltage transformers are electrically connected to the power control module and are used to connect one-to-one with the three-phase lines at the grid connection point.

[0010] In one embodiment, the voltage acquisition module further includes a first resistor, one end of the primary side of the first voltage transformer is electrically connected to the grid connection point, and the other end is grounded, the secondary side of the first voltage transformer is connected in parallel with the first resistor, one end of the secondary side of the first voltage transformer is electrically connected to the power control module, and the other end is grounded.

[0011] In one embodiment, the current acquisition module further includes a second resistor, one end of the primary side of the first current transformer is electrically connected to the grid connection point, and the other end is grounded, the secondary side of the first current transformer is connected in parallel with the second resistor, one end of the secondary side of the first current transformer is electrically connected to the power control module, and the other end is grounded.

[0012] In one embodiment, the frequency modulation device further includes an AGC receiving module, an AGC output module, and a motion module. The AGC receiving module and the AGC output module are both communicatively connected to the power control module. The motion module is also communicatively connected to the power control module. The AGC receiving module is used to communicate with the AGC system to receive AGC command information, AGC activation information, and AGC deactivation information. The AGC output module is used to output AGC lockout information or AGC unlock information to the AGC system. The motion module is used to communicate with the AGC system and the dispatch center.

[0013] Secondly, this utility model also provides a photovoltaic power station, including a photovoltaic array and a frequency modulation device as described in any one of the embodiments of the first aspect. The photovoltaic array includes multiple power generation units, each of which includes multiple string inverters, and the frequency modulation device is electrically connected to the photovoltaic array.

[0014] Thirdly, this utility model also provides a photovoltaic system, including a power grid, a dispatch center, and a photovoltaic power station as described in any one of the embodiments of the second aspect, wherein the photovoltaic array and the frequency modulation device are both electrically connected to the power grid, and the frequency modulation device is communicatively connected to the dispatch center.

[0015] The frequency modulation device includes a power control module, a main switch, multiple sub-switches, and multiple monitoring modules. The power control module is electrically connected to the grid at the grid connection point to obtain the voltage and current of the grid connection point. The main switch is connected to the power control module via fiber optic communication. The multiple sub-switches are connected to the main switch via fiber optic communication. The multiple monitoring modules are connected to the multiple sub-switches one-to-one via fiber optic communication and are configured to correspond one-to-one with multiple power generation units. Each monitoring module is electrically connected to multiple string inverters of the corresponding power generation unit. The power control module obtains the active power of multiple string inverters sequentially through multiple monitoring modules, multiple sub-switches, and the main switch. The power control module also outputs power adjustment commands to multiple string inverters according to the voltage and current of the grid connection point and the active power of multiple string inverters. This allows the power control module to receive the active power of each string inverter through the all-fiber optic communication network between the main switch, multiple sub-switches, and multiple monitoring modules, reducing the delay in the frequency modulation device's reception of the active power of the string inverters. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a photovoltaic system according to one embodiment;

[0018] Figure 2 This is a schematic diagram of the structure of a photovoltaic power station according to one embodiment;

[0019] Figure 3 This is a schematic diagram of the structure of a monitoring module according to one embodiment;

[0020] Figure 4 This is a schematic diagram of the voltage acquisition module and the current acquisition module in one embodiment.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1000 - Photovoltaic System, 100 - Photovoltaic Power Station, 10 - Frequency Regulation Device, 11 - Power Control Module, 12 - Main Switch, 13 - Sub-Switch, 14 - Monitoring Module, 141 - Measurement and Control Unit, 142 - Regulation Unit, 15 - Voltage Acquisition Module, 151 - First Voltage Transformer, 152 - Second Voltage Transformer, 153 - Third Voltage Transformer, R1 - First Resistor, R2 - Second Resistor, R3 - Third Resistor, 16 - Current Acquisition Module, 161 - First Current Transformer 162-Second current transformer, 163-Third current transformer, R4-Fourth resistor, R5-Fifth resistor, R6-Sixth resistor, 17-AGC receiving module, 18-AGC output module, 19-Motion module, 20-Photovoltaic array, 21-Power generation unit, 22-String inverter, 23-Collector line, 24-Box transformer, 25-Photovoltaic string, 30-Step-up substation, 40-Transmission line, 50-AGC system, 200-Power grid, 300-Dispatch center. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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.

[0024] It should be noted that when a component is said to be "fixed" to another component, it can be directly on the other component or it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0026] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] Please refer to Figure 1 This utility model provides a photovoltaic system 1000, including a power grid 200, a dispatch center 300, and a photovoltaic power station 100 in this embodiment of the utility model. The photovoltaic array 20 and the frequency modulation device 10 are both electrically connected to the power grid 200, and the frequency modulation device 10 is communicatively connected to the dispatch center 300.

[0028] In a specific implementation, the photovoltaic power station 100 is connected to the power grid 200 through the step-up substation 30 and the transmission line 40 to inject electrical energy into the power grid 200. When the operating information of the power grid 200 experiences instantaneous fluctuations, it is necessary to compensate for the voltage, power, and frequency of the power grid 200 to restore it to normal operating status. The photovoltaic power station 100 is used to collect and monitor the operating information of the power grid 200, such as voltage, current, load, and frequency, in real time. Under the control of the dispatch center 300, it adjusts the power output of the photovoltaic power station 100 into the power grid 200 according to the operating information of the power grid 200 and the operating status of the photovoltaic power station 100, thereby realizing real-time monitoring and supplementation of the frequency of the power grid 200 to ensure the safe and reliable operation of power generation equipment and power consumption equipment and prevent the power grid 200 from collapsing.

[0029] Please refer to Figure 2 This utility model provides a photovoltaic power station 100, including a photovoltaic array 20 and a frequency modulation device 10 in the embodiment of this utility model. The photovoltaic array 20 includes multiple power generation units 21, and each power generation unit 21 includes multiple string inverters 22. The frequency modulation device 10 is electrically connected to the photovoltaic array 20.

[0030] In a specific implementation, each power generation unit 21 also includes a collector line 23, multiple box-type transformers 24, and multiple photovoltaic strings 25. The collector line 23 is electrically connected to the output terminals of the multiple box-type transformers 24. The AC terminals of the multiple box-type transformers 24 and multiple string inverters 22 are electrically connected one-to-one. The DC terminal of each string inverter 22 is connected to multiple photovoltaic strings 25. The photovoltaic strings 25 are used to convert light energy into electrical energy. The string inverters 22 are used to convert the DC power output from the photovoltaic strings 25 into AC power input to the box-type transformers 24. The box-type transformers 24 are used to step up the low-voltage AC power output from the string inverters 22 to medium-voltage AC power input to the collector line 23. The multiple power generation units 21 input the medium-voltage AC power to the step-up substation 30 through their collector lines 23. The step-up substation 30 further increases the medium-voltage AC power to the grid 200 level voltage and inputs it into the grid 200 through the transmission line 40. The frequency regulation device 10 can adjust the power output of the photovoltaic power station 100 input to the grid 200 according to the working information of the grid 200 and the working status of the photovoltaic power station 100 under the control of the dispatch center 300, so as to realize real-time monitoring and supplementation of the frequency of the grid 200, so as to ensure the safe and reliable operation of the power generation equipment and the power consumption equipment and prevent the grid 200 from collapsing.

[0031] Please refer to Figure 2 and Figure 3 This utility model provides a frequency modulation device 10, which includes a power control module 11, a main switch 12, multiple sub-switches 13, and multiple monitoring modules 14. The power control module 11 is electrically connected to the grid 200 at the grid connection point to receive the voltage and current of the grid connection point. The main switch 12 is optically connected to the power control module 11, and the multiple sub-switches 13 are optically connected to the main switch 12. The multiple monitoring modules 14 are optically connected to the multiple sub-switches 13 one-to-one and are configured to correspond one-to-one with multiple power generation units 21. Each monitoring module 14 is electrically connected to multiple string inverters 22 of the corresponding power generation unit 21. The power control module 11 is used to obtain the active power of the multiple string inverters 22 in sequence through the multiple monitoring modules 14, multiple sub-switches 13, and the main switch 12. The power control module 11 is also used to output power adjustment commands to the multiple string inverters 22 according to the voltage and current of the grid connection point and the active power of the multiple string inverters 22.

[0032] In a specific implementation, each monitoring module 14 includes multiple measurement and control units 141. Each measurement and control unit 141 is optically connected to a corresponding sub-switch 13. The multiple measurement and control units 141 are electrically connected one-to-one with multiple string inverters 22 of the corresponding power generation unit 21, and are used to collect the active power of the string inverters 22. The measurement and control units 141 are located within the corresponding box-type transformer 24, serving as the measurement and control device for the box-type transformer 24.

[0033] Specifically, each measurement and control unit 141 transmits the active power of its corresponding string inverter 22 to its corresponding sub-switch 13. The sub-switch 13, on the one hand, transmits the active power of all the string inverters 22 it receives to the main switch 12, and on the other hand, transmits the sum of the active power of all the string inverters 22 it receives to the main switch 12. The main switch 12, on the other hand, transmits the active power of all the string inverters 22 it receives to the power control module 11, and on the other hand, transmits the sum of the active power of all the string inverters 22 it receives to the power control module 11, that is, it transmits the total active power of the photovoltaic array 20 to the power control module 11. The power module uploads the total active power of the photovoltaic array 20 to the dispatch center 300 via the motion module 19. When the dispatch center 300 needs to compensate the frequency of the power grid 200, it transmits a dispatch command to the power control module 11 via the motion module 19. The power control module 11 performs a frequency adjustment based on the dispatch command, the active power of the power grid 200, and the total active power of the photovoltaic array 20. It then outputs corresponding power adjustment commands to each string inverter 22 of the photovoltaic array 20 to control the magnitude of its output active power, thereby adjusting the power generation of the photovoltaic power station 100 input to the power grid 200.

[0034] In a specific implementation, each monitoring module 14 further includes multiple regulation units 142, each of which is optically connected to a corresponding sub-switch 13. Each regulation unit 142 is electrically connected to a corresponding string inverter 22 of the power generation unit 21, and outputs power regulation commands to the corresponding string inverter 22. The power control module 11 outputs corresponding power regulation commands to each regulation unit 142, and each regulation unit 142 controls the active power output of each string inverter 22 according to its received power regulation command. Optionally, the regulation unit 142 can be a data acquisition unit for the photovoltaic array 20.

[0035] In a specific embodiment, the frequency modulation device 10 further includes a voltage acquisition module 15 and a current acquisition module 16. Both the voltage acquisition module 15 and the current acquisition module 16 are electrically connected to the power control module 11 and are both used to be electrically connected to the grid connection point. The voltage acquisition module 15 is used to acquire the voltage of the grid connection point, and the current acquisition module 16 is used to acquire the current of the grid connection point.

[0036] Specifically, the grid connection point is the high-voltage side of the booster station 30 of the photovoltaic power station 100 or the output terminal of the transmission line 40. The power control module 11 uses the full-wave Fourier method to calculate the fundamental positive sequence active power and the effective value of the voltage at the grid connection point based on the grid connection point voltage and grid connection point current. It also calculates the grid connection point frequency based on the grid connection point voltage module.

[0037] For a detailed implementation, please refer to Figure 4 The voltage acquisition module 15 includes a first voltage transformer 151, a second voltage transformer 152, and a third voltage transformer 153. All three voltage transformers are electrically connected to the power control module 11. These transformers are used for one-to-one electrical connection with the three-phase lines at the grid connection point. The current acquisition module 16 includes a first current transformer 161. The first current transformer 161, the second current transformer 162, and the third current transformer 163 are all electrically connected to the power control module 11. The first current transformer 161, the second current transformer 162, and the third current transformer 163 are used to electrically connect one-to-one with the three-phase lines of the grid connection point, so as to input the three-phase AC power of the grid connection point into the power acquisition module respectively, thereby improving the accuracy of the power module in regulating the string inverter 22.

[0038] In a specific embodiment, the first voltage transformer 151 and the first current transformer 161 are both connected to one phase of the grid connection point, the second voltage transformer 152 and the second current transformer 162 are both connected to another phase of the grid connection point, and the third voltage transformer 153 and the third current transformer 163 are both connected to yet another phase of the grid connection point. In another specific embodiment, the first voltage transformer 151, the second voltage transformer 152, the third voltage transformer 153, the first current transformer 161, the second current transformer 162, and the third current transformer 163 are all connected to the I / O interface of the power control module 11.

[0039] In a specific embodiment, the voltage acquisition module 15 further includes a first resistor R1. One end of the primary side of the first voltage transformer 151 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the first voltage transformer 151 is connected in parallel with the first resistor R1. One end of the secondary side of the first voltage transformer 151 is electrically connected to the power control module 11, and the other end is grounded. The current acquisition module 16 further includes a second resistor R2. One end of the primary side of the first current transformer 161 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the first current transformer 161 is connected in parallel with the second resistor R2. One end of the secondary side of the first current transformer 161 is electrically connected to the power control module 11, and the other end is grounded.

[0040] Furthermore, the structures of the second voltage transformer 152 and the third voltage transformer 153 are similar to those of the first voltage transformer 151, and the structures of the second current transformer 162 and the third current transformer 163 are similar to those of the first current transformer 161. Specifically, the voltage acquisition module 15 also includes a third resistor R3. One end of the primary side of the second voltage transformer 152 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the second voltage transformer 152 is connected in parallel with the third resistor R3. One end of the secondary side of the second voltage transformer 152 is electrically connected to the power control module 11, and the other end is grounded. The current acquisition module 16 also includes a fourth resistor R4. One end of the primary side of the second current transformer 162 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the second current transformer 162 is connected in parallel with the fourth resistor R4. One end of the secondary side of the second current transformer 162 is electrically connected to the power control module 11, and the other end is grounded. The voltage acquisition module 15 also includes a fifth resistor R5. One end of the primary side of the third voltage transformer 153 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the third voltage transformer 153 is connected in parallel with the fifth resistor R5. One end of the secondary side of the third voltage transformer 153 is electrically connected to the power control module 11, and the other end is grounded. The current acquisition module 16 also includes a sixth resistor R6. One end of the primary side of the third current transformer 163 is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the third current transformer 163 is connected in parallel with the sixth resistor R6. One end of the secondary side of the third current transformer 163 is electrically connected to the power control module 11, and the other end is grounded.

[0041] Please refer to Figure 2In a specific embodiment, the frequency modulation device 10 further includes an AGC receiving module 17, which is communicatively connected to the power control module 11. The AGC receiving module 17 is used to communicate with the AGC system 50 to receive AGC command information, AGC activation information, and AGC deactivation information. The frequency modulation device 10 also includes an AGC output module 18, which is electrically connected to the power control module 11. The AGC output module 18 is used to output AGC lockout information or AGC unlock information to the AGC system 50. The frequency modulation device 10 also includes a motion module 19, which is communicatively connected to the power control module 11. The motion module 19 is used to communicate with the AGC system 50 and the dispatch center 300.

[0042] The dispatch center 300 is used to send AGC command information, AGC activation information, and AGC deactivation information to the AGC system 50 of the photovoltaic power station 100 via the motion module 19. The power control module 11 is used to receive AGC command information through the AGC command information reading module of the AGC receiving module 17, and to receive AGC activation information and AGC deactivation information through the AGC activation / deactivation information reading module of the AGC receiving module 17. It also sends AGC lockout information or AGC unlock information to the AGC system 50 through the AGC lockout / unlock information module of the AGC output module 18. In addition, the power control module 11 is also used to send real-time data of the photovoltaic power station 100 to the dispatch center 300 via the motion module 19, including equipment status, active power of the photovoltaic array 20, actual output power, voltage and current of the photovoltaic power station 100, and primary frequency regulation action information generated by the power control module 11.

[0043] The frequency modulation device 10 includes a power control module 11, a main switch 12, multiple sub-switches 13, and multiple monitoring modules 14. The power control module 11 is electrically connected to the power grid 200 to receive its operating information. The main switch 12 is optically connected to the power control module 11. The multiple sub-switches 13 are optically connected to the main switch 12. The multiple monitoring modules 14 are optically connected to each of the sub-switches 13 and are configured to correspond to multiple power generation units 21. Each monitoring module 14 is electrically connected to multiple string inverters 22 of the corresponding power generation unit 21. The control module 11 is used to obtain the active power of multiple string inverters 22 sequentially through multiple monitoring modules 14, multiple sub-switches 13 and the main switch 12. The power control module 11 is also used to output power adjustment commands to multiple string inverters 22 according to the working information of the power grid 200 and the active power of multiple string inverters 22, so that the power control module 11 can receive the active power of each string inverter 22 through the all-fiber communication network between the main switch 12, multiple sub-switches 13 and multiple monitoring modules 14, thereby reducing the delay of the frequency modulation device 10 in receiving the active power of the string inverters 22.

[0044] In the description of the embodiments of this utility model, it should be noted that the orientation or positional relationship of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and other indicators are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0045] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present utility model are still within the scope of the present utility model.

Claims

1. A frequency modulation device, characterized in that, For use in photovoltaic power plants, the photovoltaic power plant includes a photovoltaic array, the photovoltaic array includes multiple power generation units, each power generation unit includes multiple string inverters, and the frequency regulation device includes: The power control module is used to connect to the grid at the grid connection point to obtain the voltage and current at the grid connection point; The main switch is connected to the power control module via fiber optic communication. Multiple sub-switches are connected to the main switch via fiber optic communication. Multiple monitoring modules are connected to multiple sub-switches via optical fiber communication and are configured to correspond to multiple power generation units. Each monitoring module is electrically connected to multiple string inverters of the corresponding power generation unit. The power control module is used to obtain the active power of multiple string inverters sequentially through multiple monitoring modules, multiple sub-switches and the main switch. The power control module is also used to output power adjustment commands to multiple string inverters according to the voltage and current of the grid connection point and the active power of the multiple string inverters.

2. The frequency modulation device according to claim 1, characterized in that, Each monitoring module includes multiple measurement and control units, each of which is connected to the corresponding sub-switch via optical fiber communication. The multiple measurement and control units are used to connect one-to-one with multiple string inverters of the corresponding power generation unit. The measurement and control units are used to collect the active power of the string inverters.

3. The frequency modulation device according to claim 1, characterized in that, Each monitoring module also includes multiple adjustment units, each of which is optically connected to a corresponding sub-switch. The multiple adjustment units are used to be electrically connected one-to-one with multiple string inverters of the corresponding power generation unit, and the adjustment units are used to output the power adjustment command to the corresponding string inverter.

4. The frequency modulation device according to claim 1, characterized in that, The frequency modulation device further includes a voltage acquisition module and a current acquisition module. Both the voltage acquisition module and the current acquisition module are electrically connected to the power control module and are used to electrically connect to the grid connection point. The voltage acquisition module is used to acquire the voltage of the grid connection point, and the current acquisition module is used to acquire the current of the grid connection point.

5. The frequency modulation device according to claim 4, characterized in that, The voltage acquisition module includes a first voltage transformer, a second voltage transformer, and a third voltage transformer. The first voltage transformer, the second voltage transformer, and the third voltage transformer are all electrically connected to the power control module. The first voltage transformer, the second voltage transformer, and the third voltage transformer are used to be electrically connected to the three-phase lines of the grid connection point one-to-one. The current acquisition module includes a first current transformer, a second current transformer, and a third current transformer. The first current transformer, the second current transformer, and the third current transformer are all electrically connected to the power control module. The first current transformer, the second current transformer, and the third current transformer are used to be electrically connected to the three-phase lines of the grid connection point one-to-one.

6. The frequency modulation device according to claim 5, characterized in that, The voltage acquisition module further includes a first resistor. One end of the primary side of the first voltage transformer is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the first voltage transformer is connected in parallel with the first resistor. One end of the secondary side of the first voltage transformer is electrically connected to the power control module, and the other end is grounded.

7. The frequency modulation device according to claim 5, characterized in that, The current acquisition module further includes a second resistor. One end of the primary side of the first current transformer is electrically connected to the grid connection point, and the other end is grounded. The secondary side of the first current transformer is connected in parallel with the second resistor. One end of the secondary side of the first current transformer is electrically connected to the power control module, and the other end is grounded.

8. The frequency modulation device according to claim 1, characterized in that, The frequency modulation device further includes an AGC receiving module, an AGC output module, and a motion module. The AGC receiving module and the AGC output module are both communicatively connected to the power control module. The motion module is also communicatively connected to the power control module. The AGC receiving module is used to communicate with the AGC system to receive AGC command information, AGC activation information, and AGC deactivation information. The AGC output module is used to output AGC lockout information or AGC unlock information to the AGC system. The motion module is used to communicate with the AGC system and the dispatch center.

9. A photovoltaic power station, characterized in that, The device includes a photovoltaic array and a frequency modulation device as described in any one of claims 1-8. The photovoltaic array includes multiple power generation units, each of which includes multiple string inverters, and the frequency modulation device is electrically connected to the photovoltaic array.

10. A photovoltaic system, characterized in that, It includes a power grid, a dispatch center, and a photovoltaic power station as described in claim 9, wherein the photovoltaic array and the frequency regulation device are both electrically connected to the power grid, and the frequency regulation device is communicatively connected to the dispatch center.

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