Voltage control method and system based on remaining capacity of photovoltaic inverter

Abstract

This invention discloses a voltage control method and system based on the remaining capacity of a photovoltaic inverter, relating to the field of power grid control optimization technology. The method includes the following steps: acquiring the power grid operating status and the inverter operating status, and analyzing to obtain the remaining capacity of the inverter; adjusting the inverter operating mode according to the remaining capacity, wherein the inverter operating mode includes normal mode, fault ride-through mode, and derating mode; obtaining a voltage regulation reference value based on the inverter operating mode, combined with active power frequency droop, reactive power voltage droop, and the remaining capacity of the inverter; adjusting the inverter output voltage according to the voltage regulation reference value, and controlling the grid voltage through the inverter output voltage. This invention addresses the multi-scenario adaptability problem of controlling distribution network voltage using the remaining capacity of a photovoltaic inverter.

Description

Technical Field

[0001] This invention relates to the field of power grid control optimization technology, and more specifically, to a voltage control method and system based on the remaining capacity of a photovoltaic inverter. Background Technology

[0002] As traditional fossil fuels are gradually phased out, the integration and grid connection of new energy sources has become one of the core tasks of modern power grid construction. Due to the intermittent and fluctuating characteristics of new energy power generation, grid dispatching, stability, and reliability face greater challenges. Therefore, optimizing the generation end to improve the integration and stability of the new energy grid has become a key technology.

[0003] For example, the invention patent announcement CN119362492A discloses a voltage-reactive power control method, device, and medium based on centralized optimization. This method provides a multi-mode optimization control method for voltage-reactive power based on centralized optimization, including: detecting and identifying commands issued by the upper-level optimization; setting a voltage regulation range and setting a local voltage-reactive power curve based on the command results; outputting a reactive power reference value for the inverter based on the local voltage-reactive power curve; adjusting the inverter's reactive power based on the inverter's reactive power reference value to regulate the grid connection point voltage until it stabilizes; determining whether the stable grid connection point voltage is within the voltage regulation range; and periodically detecting the grid connection point voltage value to determine whether the detected grid connection point voltage fluctuates significantly. This invention improves the inverter's compatibility with upper-level optimization, effectively suppresses grid voltage fluctuations and over-limits, and improves the inverter's voltage support capability, grid voltage quality, and grid operation reliability.

[0004] For example, the invention patent announcement CN120613798A discloses a grid-connected control method for a photovoltaic power generation system. This method includes the following steps: calculating a first virtual inertia when the grid frequency decreases and a second virtual inertia when the grid frequency increases based on the characteristic parameters of the photovoltaic power generation system; selecting either the first or second virtual inertia as the current value of the virtual inertia of the photovoltaic power generation system; obtaining a reference voltage phase angle and a reference voltage amplitude based on the characteristic parameters of the photovoltaic power generation system and the current value of the virtual inertia; calculating the d-axis reference voltage and the q-axis reference voltage based on the reference voltage phase angle and the reference voltage amplitude; calculating a modulation signal Ed based on the d-axis reference voltage and a modulation signal Eq based on the q-axis reference voltage; generating a PWM drive signal after the modulation signals Ed and Eq undergo an abc / dq transformation; and inputting the PWM drive signal to each switch of the photovoltaic inverter to complete the grid-connected control of the photovoltaic power generation system.

[0005] The above-disclosed technical solutions have at least the following technical problems:

[0006] In new energy systems, the control methods for related equipment at the grid connection point are not adequately considered in special scenarios, making it difficult to fully utilize the remaining capacity of inverters to regulate and improve the stability of the new energy distribution network.

[0007] To address the above problems, this invention proposes a solution. Summary of the Invention

[0008] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a voltage control method and system based on the remaining capacity of photovoltaic inverters. By considering the normal mode, fault ride-through mode, and derating mode for restoring the remaining capacity of the inverter under the influence of the remaining capacity limitation of the photovoltaic inverter, the method and system address the multi-scenario adaptability problem of controlling the distribution network voltage with the remaining capacity of the photovoltaic inverter.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A voltage control method based on the remaining capacity of a photovoltaic inverter includes the following steps: acquiring the grid operating status and the inverter operating status, and analyzing to obtain the remaining capacity of the inverter; adjusting the inverter operating mode according to the remaining capacity, wherein the inverter operating mode includes normal mode, fault ride-through mode, and derating mode; obtaining a voltage regulation reference value based on the inverter operating mode, combined with active frequency droop, reactive voltage droop, and the remaining capacity of the inverter; adjusting the inverter output voltage according to the voltage regulation reference value, and controlling the grid voltage through the inverter output voltage.

[0011] In a preferred embodiment, the analysis to obtain the remaining capacity of the inverter includes the correction of the remaining capacity of the inverter, specifically: obtaining the initial value of the remaining capacity of each inverter in the inverter group according to the depreciation method; evaluating the health status of each inverter through the historical operating status, historical regional load and historical environmental data of each inverter; correcting the initial value of the remaining capacity according to the health status of each inverter to obtain the remaining capacity of each inverter.

[0012] In a preferred embodiment, after the analysis yields the remaining capacity of the inverters, the method further includes sorting the inverters, specifically: sorting the inverters according to the corrected remaining capacity, and obtaining the priority of each inverter according to its operating status; and adjusting the sorting of the inverters according to their priority.

[0013] In a preferred embodiment, adjusting the inverter operating mode according to the remaining inverter capacity specifically includes: maintaining the normal mode when the remaining inverter capacity is stable; adjusting to the fault ride-through mode when the remaining inverter capacity drops sharply; and adjusting to the derating mode when the remaining inverter capacity gradually decreases to a preset inverter threshold.

[0014] In a preferred embodiment, the normal mode specifically includes: adjusting a first active power reference value based on grid frequency deviation and active power droop parameters; adjusting a first reactive power reference value based on grid voltage deviation and reactive power droop parameters; limiting the first reactive power reference value based on the inverter's remaining capacity; and obtaining a voltage regulation reference value through a power control loop, wherein the voltage regulation reference value includes a voltage reference value and a phase reference value.

[0015] In a preferred embodiment, the fault ride-through mode specifically includes: maximizing the second reactive power reference value based on the inverter's remaining capacity limit; and adjusting the second active power reference value based on the capacity margin if the reactive power support condition is met.

[0016] In a preferred embodiment, the derating mode specifically includes: removing the limitation of the inverter's remaining capacity on the reactive power reference value; reducing the third active power reference value according to a preset gradient until the inverter's remaining capacity is restored; and adjusting the third reactive power reference value according to the grid voltage deviation and reactive power droop parameters.

[0017] In a preferred embodiment, the step of obtaining a voltage regulation reference value by combining active frequency droop, reactive voltage droop, and inverter remaining capacity further includes optimizing the droop parameters through reinforcement learning. Specifically, this involves: constructing a state set using the normalized values ​​of voltage deviation, frequency deviation, active power, and reactive power; constructing an action set using the active power droop parameters and reactive power droop parameters; constructing a droop reward function with the objective of minimizing power fluctuations, voltage fluctuations, and frequency fluctuations; and outputting the optimized droop parameters based on the state set, action set, and droop reward function using a reinforcement learning algorithm.

[0018] In a preferred embodiment, adjusting the inverter output voltage according to the voltage regulation reference value specifically involves: distributing the voltage regulation reference value to each inverter via a dynamic proportional distribution; the dynamic proportional distribution is based on the order of the inverters.

[0019] A voltage control system based on the remaining capacity of a photovoltaic inverter includes: an inverter remaining capacity analysis module for acquiring the grid operating status and the inverter operating status, and analyzing to obtain the inverter's remaining capacity; a working mode switching module for adjusting the inverter's working mode according to the inverter's remaining capacity, wherein the inverter's working mode includes normal mode, fault ride-through mode, and derating mode; a parameter adjustment module for obtaining a voltage regulation reference value based on the inverter's working mode, combined with active frequency droop, reactive voltage droop, and the inverter's remaining capacity; and an inverter control module for adjusting the inverter's output voltage according to the voltage regulation reference value, and controlling the grid voltage through the inverter's output voltage.

[0020] The technical effects and advantages of this invention regarding the voltage control method and system based on the remaining capacity of photovoltaic inverters are as follows:

[0021] This invention effectively solves the multi-scenario adaptability problem of controlling the distribution network voltage with the remaining capacity of photovoltaic inverters by considering the normal mode, fault ride-through mode and derating mode under the influence of the remaining capacity limitation of photovoltaic inverters, and combining the active and reactive power interaction between photovoltaic inverters and distribution networks, thereby precisely controlling the electrical attributes of the grid connection point of the new energy distribution network at multiple levels. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a voltage control method based on the remaining capacity of a photovoltaic inverter, provided in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of a voltage control system structure based on the remaining capacity of a photovoltaic inverter, provided in an embodiment of the present invention. Detailed Implementation

[0024] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1, Figure 1 The present invention provides a voltage control method based on the remaining capacity of a photovoltaic inverter, comprising the following steps:

[0026] S1: Obtain the grid operation status and inverter operation status, and analyze to obtain the remaining capacity of the inverter;

[0027] S2, adjust the inverter operating mode according to the remaining capacity of the inverter, the inverter operating mode includes normal mode, fault ride-through mode and derating mode;

[0028] S3. Based on the inverter's operating mode, combined with the active frequency droop, reactive voltage droop, and the inverter's remaining capacity, the voltage regulation reference value is obtained.

[0029] S4 adjusts the inverter output voltage according to the voltage regulation reference value, and controls the grid voltage through the inverter output voltage.

[0030] S1: Obtain the grid operating status and inverter operating status, and analyze to obtain the remaining capacity of the inverter.

[0031] In this embodiment, the analysis to obtain the remaining capacity of the inverter includes a correction to the remaining capacity of the inverter, specifically:

[0032] The initial value of the remaining capacity of each inverter in the inverter group is obtained by using the straight-line depreciation method.

[0033] The health status of each inverter is assessed by analyzing its historical operating data, historical regional load data, and historical environmental data.

[0034] The initial value of the remaining capacity is adjusted according to the health status of each inverter to obtain the remaining capacity of each inverter.

[0035] In this embodiment, the formula for calculating the initial value of the remaining capacity of each inverter is as follows:

[0036]

[0037] In the formula, Let this be the initial value of the remaining capacity of the i-th inverter. Let i be the rated power of the i-th inverter. Let be the service life of the i-th inverter. Let i be the design life of the i-th inverter. Let be the output power of the i-th inverter.

[0038] In this embodiment, the health status of each inverter is evaluated based on its historical operating data, historical regional load data, and historical environmental data. Specifically:

[0039] Based on the acquired historical runtime and historical environmental data, the equivalent parameters of heat loss are obtained;

[0040] Based on the obtained historical output power and historical operating time, the equivalent load parameters are obtained;

[0041] Based on the equivalent parameters of heat loss and load, the state evaluation parameters of each inverter are obtained.

[0042] In this embodiment, the equivalent heat loss parameter is specifically formulated as follows:

[0043]

[0044] In the formula, For heat loss equivalent parameters, Light intensity during the time period For standard testing of light intensity, Temperature during the time period For standard test temperature, The duration of the period This represents the total runtime.

[0045] In this embodiment, the equivalent load parameter is specifically formulated as follows:

[0046]

[0047] In the formula, For load equivalent parameters, Output power for a given time period The standard test is to measure the rated power of the inverter.

[0048] In this embodiment, the inverter state evaluation parameters are specifically formulated as follows:

[0049]

[0050] In the formula, These are parameters for inverter condition assessment. The normalized equivalent heat loss parameter, These are the normalized equivalent load parameters. and These are machine learning coefficients.

[0051] In this embodiment, the initial value of the remaining capacity is corrected according to the health status of each inverter. The specific formula for the correction is as follows:

[0052]

[0053] In the formula, The remaining capacity after correction for the i-th inverter. Let this be the initial value of the remaining capacity of the i-th inverter. These are the inverter state evaluation parameters for the i-th inverter.

[0054] In this embodiment, after obtaining the remaining capacity of the inverters through analysis, the method further includes sorting the inverters, specifically:

[0055] The inverters are sorted according to their corrected remaining capacity, and their priority is determined based on their operating status.

[0056] The order of inverters is adjusted according to their priority.

[0057] It should be noted that the priority of each inverter is negatively correlated with the preset gradient level of each inverter's operating status.

[0058] It should be noted that the operating status of each inverter refers to the real-time output power of each inverter. Priority is set according to the operating status of each inverter, thereby delaying the sorting position of inverters under high load conditions, reducing the probability of inverters under high load conditions being selected, and thus slowing down the loss of inverter lifespan.

[0059] It should be noted that this embodiment obtains a more accurate remaining capacity of the photovoltaic inverter by initially assessing the remaining capacity based on the number of years and correcting the initial value according to the health status of each inverter. This provides a more accurate basis for subsequent steps and effectively improves the control effect of the overall control process.

[0060] S2, adjust the inverter operating mode according to the remaining capacity of the inverter. The inverter operating modes include normal mode, fault ride-through mode and derating mode.

[0061] In this embodiment, adjusting the inverter's operating mode based on its remaining capacity specifically involves:

[0062] The inverter's remaining capacity is stable, maintaining normal operating mode;

[0063] The inverter's remaining capacity has decreased sharply, so it has been switched to fault ride-through mode.

[0064] The remaining capacity of the inverter gradually decreases to the preset inverter threshold, and the inverter is switched to derating mode.

[0065] It should be noted that "stable remaining inverter capacity" means that the remaining inverter capacity fluctuates within a certain range; "sudden decrease in remaining inverter capacity" means that the rate of decrease in remaining inverter capacity increases rapidly in a short period of time; and "gradual decrease in remaining inverter capacity to a preset inverter threshold" means that the remaining inverter capacity decreases to the preset inverter threshold at a rate lower than the preset rate of decrease.

[0066] In this embodiment, the normal mode specifically includes:

[0067] Adjust the first active power reference value according to the grid frequency deviation and active power droop parameter;

[0068] Adjust the first reactive power reference value according to the grid voltage deviation and reactive power droop parameter;

[0069] And limit the first reactive power reference value based on the remaining capacity of the inverter;

[0070] The voltage regulation reference value is obtained through the power control loop, and the voltage regulation reference value includes a voltage reference value and a phase reference value.

[0071] In this embodiment, the specific formula for the first active power reference value is as follows:

[0072]

[0073] In the formula, This is the first active power reference value. The target active power at the grid connection point. For the grid frequency deviation at the grid connection point, This is the active power droop parameter.

[0074] In this embodiment, the specific formula for the first reactive power reference value is as follows:

[0075]

[0076] In the formula, This is the first reactive power reference value. The target reactive power at the grid connection point. For the grid voltage deviation at the grid connection point, This is the reactive power droop parameter.

[0077] It should be noted that the grid frequency deviation at the grid connection point refers to the deviation between the current grid frequency and the target grid frequency; the grid voltage deviation at the grid connection point refers to the deviation between the current grid voltage and the target grid voltage.

[0078] In this embodiment, the specific formula for limiting the first reactive power reference value by the remaining capacity of the inverter is as follows:

[0079]

[0080] In the formula, The inverter's remaining capacity limitation function is defined by the first reactive power reference value. This is the first reactive power reference value. This represents the remaining capacity of the inverter group.

[0081] It should be noted that the existing technology for obtaining voltage regulation reference values ​​through the power control loop, based on known active power and reactive power reference values, will not be repeated here.

[0082] In this embodiment, the fault-crossing mode specifically includes:

[0083] Maximize the second reactive power reference value based on the inverter's remaining capacity limit;

[0084] If the reactive power support conditions are met, the second active power reference value is adjusted according to the capacity margin.

[0085] In this embodiment, the specific formula for the capacity margin is:

[0086]

[0087] In the formula, For capacity margin, The second reactive power reference value is used to meet the reactive power support conditions.

[0088] In this embodiment, the specific formula for the second active power reference value is as follows:

[0089]

[0090] In the formula, This is the second active power reference value. This represents the active power before the fault.

[0091] In this embodiment, the throttling mode specifically includes:

[0092] Remove the limitation imposed by the inverter's remaining capacity on the reactive power reference value;

[0093] The third active power reference value is reduced according to the preset gradient until the remaining capacity of the inverter is restored;

[0094] Adjust the third reactive power reference value according to the grid voltage deviation and reactive power droop parameter.

[0095] In this embodiment, the specific formula for the third active power reference value is as follows:

[0096]

[0097] In the formula, This is the third active power reference value. For the preset gradient coefficients, This is the preset inverter threshold.

[0098] In this embodiment, the specific formula for the third reactive power reference value is as follows:

[0099]

[0100] In the formula, This is the third reactive power reference value.

[0101] It should be noted that this embodiment effectively ensures the adaptability of adjusting grid-connected power by inverter remaining capacity under different scenarios by considering the normal mode, fault ride-through mode and derating mode for restoring inverter remaining capacity under the influence of inverter remaining capacity limitation.

[0102] S3, based on the inverter's operating mode, combined with the active frequency droop, reactive voltage droop, and the inverter's remaining capacity, obtains the voltage regulation reference value.

[0103] In this embodiment, the process of obtaining a voltage regulation reference value by combining active frequency droop, reactive voltage droop, and inverter remaining capacity also includes optimizing the droop parameters through reinforcement learning, specifically:

[0104] A state set is constructed using the normalized values ​​of voltage deviation, frequency deviation, active power, and reactive power.

[0105] Construct an action set using active power droop parameters and reactive power droop parameters;

[0106] A drooping reward function is constructed with the goal of minimizing power fluctuations, voltage fluctuations, and frequency fluctuations.

[0107] Based on the state set, action set, and droop reward function, the optimized droop parameters are output using a reinforcement learning algorithm.

[0108] In this embodiment, the specific formula for the drooping reward function is as follows:

[0109]

[0110] In the formula, For the drooping reward function, This represents the change in active power. This represents the change in reactive power. , , and These are preset weighting coefficients.

[0111] It should be noted that the preset weighting coefficients are derived from expert experience.

[0112] It should be noted that this embodiment obtains droop parameters that are more consistent with the actual situation through reinforcement learning, and then applies them to the inverter control mode, which enhances the stability of the interaction between the photovoltaic inverter and the distribution network, and further enhances the robustness of the grid-connected voltage control strategy through the inverter.

[0113] S4 adjusts the inverter output voltage according to the voltage regulation reference value, and controls the grid voltage through the inverter output voltage.

[0114] In this embodiment, adjusting the inverter output voltage according to the voltage regulation reference value specifically means:

[0115] The voltage regulation reference value is dynamically proportionally distributed to each inverter.

[0116] The dynamic proportional allocation is based on the order of each inverter.

[0117] In this embodiment, the dynamic proportional allocation specifically refers to:

[0118] The adjustment task is allocated according to the proportion of the remaining capacity of each inverter.

[0119] If the regulation task assigned to an inverter exceeds its remaining capacity regulation capability, the inverter will be clamped to its maximum regulation capability and removed from the allocation list.

[0120] Based on the remaining inverter capacity, the ratio is recalculated and the remaining regulation tasks are allocated.

[0121] It should be noted that this embodiment sorts the photovoltaic inverters in advance according to their remaining capacity, adjusts the sorting according to their operating status, and combines dynamic proportional allocation. This effectively ensures that the remaining control capacity of each inverter is fully utilized without exceeding the limit, while reducing the probability of inverters being selected under high load conditions, thereby effectively extending the service life of the inverters.

[0122] Example 2, Figure 2 This invention presents a voltage control system based on the remaining capacity of a photovoltaic inverter, comprising:

[0123] The inverter remaining capacity analysis module is used to obtain the grid operating status and inverter operating status, and analyze the remaining capacity of the inverter.

[0124] The working mode switching module is used to adjust the inverter working mode according to the remaining capacity of the inverter. The inverter working modes include normal mode, fault ride-through mode and derating mode.

[0125] The parameter adjustment module is used to obtain the voltage adjustment reference value based on the inverter's operating mode, combined with the active frequency droop, reactive voltage droop, and the inverter's remaining capacity.

[0126] The inverter control module is used to adjust the inverter output voltage according to the voltage regulation reference value, and to control the grid voltage through the inverter output voltage.

[0127] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0128] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0129] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0130] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0131] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0132] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A voltage control method based on the remaining capacity of a photovoltaic inverter, characterized in that, The method comprises the following steps: obtaining grid operation state and inverter operation state, and analyzing to obtain inverter residual capacity; adjusting inverter operation mode according to inverter residual capacity, specifically: maintaining normal mode when inverter residual capacity is stable; adjusting to fault ride-through mode when inverter residual capacity suddenly decreases; adjusting to derated mode when inverter residual capacity slowly decreases to a preset inverter threshold value; the inverter operation mode comprises normal mode, fault ride-through mode and derated mode; the normal mode comprises: adjusting a first active power reference value according to grid frequency deviation and active power droop parameter; adjusting a first reactive power reference value according to grid voltage deviation and reactive power droop parameter; and limiting the first reactive power reference value according to inverter residual capacity; obtaining a voltage regulation reference value through a power control loop, wherein the voltage regulation reference value comprises a voltage reference value and a phase reference value; the fault ride-through mode comprises: limiting a second reactive power reference value according to inverter residual capacity, and maximizing the second reactive power reference value; and adjusting a second active power reference value according to capacity margin if a reactive power support condition is met; the derated mode comprises: removing the limitation of inverter residual capacity on the reactive power reference value; reducing a third active power reference value according to a preset gradient until the inverter residual capacity is restored; and adjusting a third reactive power reference value according to grid voltage deviation and reactive power droop parameter; obtaining a voltage regulation reference value according to inverter operation mode, active frequency droop, reactive voltage droop and inverter residual capacity, further comprising optimizing droop parameters, specifically: constructing a state set by using normalized values of voltage deviation, frequency deviation, active power and reactive power; constructing an action set by using active power droop parameter and reactive power droop parameter; constructing a droop reward function by taking minimizing power fluctuation, voltage fluctuation and frequency fluctuation as a target; and outputting optimized droop parameters based on reinforcement learning algorithm according to the state set, the action set and the droop reward function; adjusting inverter output voltage according to the voltage regulation reference value, and controlling grid voltage through the inverter output voltage.

2. The method of voltage control based on the remaining capacity of a photovoltaic inverter according to claim 1, characterized in that, the analysis of inverter residual capacity comprises correction of inverter residual capacity, specifically: obtaining initial values of inverter residual capacity of each inverter in an inverter group according to the depreciation method of years; evaluating the health status of each inverter through historical operation conditions, historical regional load and historical environmental data of each inverter; correcting the initial values of inverter residual capacity according to the health status of each inverter to obtain the inverter residual capacity of each inverter.

3. The method of voltage control based on the remaining capacity of a photovoltaic inverter according to claim 2, characterized in that, after the analysis of inverter residual capacity, further comprising sorting each inverter, specifically: sorting each inverter according to the corrected inverter residual capacity, and obtaining the priority of each inverter according to the operation state of each inverter; adjusting the sorting of each inverter according to the priority of each inverter.

4. The method of voltage control based on the remaining capacity of a photovoltaic inverter according to claim 3, characterized in that, the adjustment of inverter output voltage according to the voltage regulation reference value, specifically: distributing the voltage regulation reference value to each inverter through dynamic proportioning; the dynamic proportioning is based on the sorting of each inverter.

5. A system using the photovoltaic inverter residual capacity-based voltage control method according to any one of claims 1 to 4, characterized in that, comprising: an inverter residual capacity analysis module for obtaining grid operation state and inverter operation state, and analyzing to obtain inverter residual capacity; The working mode switching module is configured to adjust the working mode of the inverter according to the remaining capacity of the inverter, specifically: when the remaining capacity of the inverter is stable, maintaining the normal mode; when the remaining capacity of the inverter suddenly decreases, adjusting to the fault ride-through mode; and when the remaining capacity of the inverter slowly decreases to a preset inverter threshold, adjusting to the derated mode; the working mode of the inverter includes the normal mode, the fault ride-through mode and the derated mode; the normal mode includes: adjusting a first active power reference value according to the grid frequency deviation and the active power droop parameter; adjusting a first reactive power reference value according to the grid voltage deviation and the reactive power droop parameter; and limiting the first reactive power reference value according to the remaining capacity of the inverter; obtaining a voltage regulation reference value through a power control loop, the voltage regulation reference value including a voltage reference value and a phase reference value; the fault ride-through mode includes: limiting the second reactive power reference value according to the remaining capacity of the inverter; and maximizing the second active power reference value according to the capacity margin if the reactive power support condition is met; the derated mode includes: removing the limitation of the remaining capacity of the inverter on the reactive power reference value; reducing a third active power reference value according to a preset gradient until the remaining capacity of the inverter is restored; and adjusting the third reactive power reference value according to the grid voltage deviation and the reactive power droop parameter; The parameter adjustment module is configured to obtain the voltage regulation reference value according to the working mode of the inverter, in combination with the active frequency droop, the reactive voltage droop and the remaining capacity of the inverter, and further includes optimizing the droop parameters, specifically: constructing a state set with the normalized values of the voltage deviation, the frequency deviation, the active power and the reactive power; constructing an action set with the active power droop parameter and the reactive power droop parameter; constructing a droop reward function with the objective of minimizing the power fluctuation, the voltage fluctuation and the frequency fluctuation; and outputting the optimized droop parameters based on the reinforcement learning algorithm according to the state set, the action set and the droop reward function; The inverter control module is configured to adjust the inverter output voltage according to the voltage regulation reference value, and control the grid voltage through the inverter output voltage.

Images