Photovoltaic inverter active power output capability assessment method, system, device and medium

Abstract

The invention provides a photovoltaic inverter active power output capability assessment method, system, device and medium, and the method comprises the steps: calculating an AC side voltage value of a photovoltaic inverter connected with a power grid in a grid-connected manner based on each target power grid voltage when the voltage of the power grid rises to the target power grid voltage; based on the alternating current side voltage value, calculating the minimum value of the lifting amount of the direct current voltage reference value of the photovoltaic inverter; outputting an active power output upper limit of the photovoltaic inverter under the target power grid voltage according to the minimum value of the lifting amount of the direct current voltage reference value; evaluating the active output capability of the photovoltaic inverter according to the active output upper limit of the photovoltaic inverter under each target power grid voltage; according to the method, the output power is kept to the maximum extent by dynamically calculating the minimum lifting amount of the direct-current voltage reference value, the active output capacity of the photovoltaic inverter is evaluated according to the active output upper limit under different power grid voltages, and the stability of the photovoltaic inverter in the high-voltage ride-through period can be clearly known.

Description

Technical Field

[0001] The present invention relates to the technical fields of new energy power generation technology and power system technology, and in particular to a method, system, device and medium for evaluating the active output capacity of a photovoltaic inverter. Background Art

[0002] As the penetration of photovoltaic power generation in power systems continues to increase, grids are placing stricter requirements on the fault ride-through capabilities of photovoltaic inverters. Fault ride-through technologies are categorized into two types: low-voltage ride-through (LVRT) and high-voltage ride-through (HVRRT). While recent research has yielded substantial results in LVRRT for grid voltage sags, research on HVRRT for grid voltage swells remains significantly limited.

[0003] In existing technology, unipolar photovoltaic inverters are widely used in small and medium-sized photovoltaic power plants due to their simple topology and low cost. However, their direct connection to the photovoltaic array presents significant challenges during high voltage ride-through (HVRT). When the grid voltage rises abnormally, the DC voltage of the photovoltaic array becomes increasingly coupled to the grid voltage, and the inverter's active power output capacity is subject to multiple constraints: the DC voltage limit, the modulation ratio margin, and the dynamic reactive power support requirement. Traditional methods typically increase the DC voltage reference value by a fixed step size or sacrifice active power to meet the reactive power support requirement. However, these strategies lack precise evaluation criteria. On the one hand, blindly increasing the DC voltage can cause the PV array operating point to deviate significantly from the maximum power point, resulting in power generation efficiency losses. On the other hand, the upper limit of active power output capacity under different voltage rise amplitudes is not quantitatively evaluated, resulting in a lack of data support for control parameter optimization, making it difficult to achieve maximum power output while ensuring stable inverter operation. Furthermore, current research focuses on improving dynamic reactive power support capability, while a systematic solution for evaluating active power control capability during HVRT has yet to be developed. Due to the lack of scientific evaluation methods, it is impossible to accurately judge the performance boundaries of the inverter under different grid voltage increase scenarios, resulting in the formulation of control strategies being more empirical and conservative, further exacerbating the problem of reduced active output capacity.

[0004] In summary, due to the lack of a dynamic quantitative evaluation method for the active output capability of the photovoltaic inverter during high voltage ride-through in the existing technology, the control strategy cannot adaptively adjust the DC voltage reference value according to the amplitude of the grid voltage rise, resulting in limited active output capability. Summary of the Invention

[0005] To address the problem in the prior art of limited active output capacity due to the lack of a dynamic quantitative evaluation method for the active output capacity of a photovoltaic inverter during high voltage ride-through, which prevents the control strategy from adaptively adjusting the DC voltage reference value according to the grid voltage rise amplitude, the present invention proposes a method for evaluating the active output capacity of a photovoltaic inverter, comprising:

[0006] Based on each target grid voltage, when the grid voltage rises to the target grid voltage, calculating an AC side voltage value of a photovoltaic inverter connected to the grid;

[0007] Calculating a minimum value of an increase in a DC voltage reference value of the photovoltaic inverter based on an AC side voltage value of the photovoltaic inverter;

[0008] outputting an upper limit of active power output of the photovoltaic inverter at the target grid voltage according to a minimum value of the DC voltage reference value increase of the photovoltaic inverter;

[0009] The active power output capability of the photovoltaic inverter is evaluated according to the active power output upper limit of the photovoltaic inverter at each target grid voltage.

[0010] Optionally, when the voltage of the grid rises to the target grid voltage, calculating the AC side voltage value of the photovoltaic inverter connected to the grid includes:

[0011] When the voltage of the grid rises to the target grid voltage, calculating a d-axis current value and a q-axis current value of a photovoltaic inverter connected to the grid;

[0012] Calculating a filter inductor voltage value of the photovoltaic inverter according to a d-axis current value and a q-axis current value of the photovoltaic inverter;

[0013] According to the filter inductor voltage value of the photovoltaic inverter, an AC side voltage value of the photovoltaic inverter under the filter inductor voltage is calculated.

[0014] Optionally, the calculating, based on the AC side voltage value of the photovoltaic inverter, a minimum value of the DC voltage reference value increase of the photovoltaic inverter includes:

[0015] comparing the AC side voltage value of the photovoltaic inverter with a pre-acquired upper limit of the output voltage of the photovoltaic inverter when in steady-state operation;

[0016] Based on the comparison result of the AC side voltage value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is calculated.

[0017] Optionally, the calculating, based on the comparison result of the AC side voltage value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter includes:

[0018] When the AC side voltage value is less than or equal to the output voltage upper limit, setting the minimum value of the DC voltage reference value increase of the photovoltaic inverter to 0;

[0019] When the AC side voltage value is greater than the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output based on a pre-calculated initial value of the increase.

[0020] Optionally, outputting a minimum value of the DC voltage reference value boost of the photovoltaic inverter based on a pre-calculated initial value of the boost includes:

[0021] Obtaining a DC voltage regulation reference value of the photovoltaic inverter according to a pre-calculated initial value of the boost amount;

[0022] Calculating, according to a DC voltage regulation reference value of the photovoltaic inverter, an AC side voltage value and an output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value;

[0023] Based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

[0024] Optionally, outputting a minimum value of an increase in the DC voltage reference value of the photovoltaic inverter based on an AC side voltage value and an output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value includes:

[0025] Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit;

[0026] According to the difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

[0027] Optionally, outputting a minimum value of the DC voltage reference value increase of the photovoltaic inverter according to a difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and an output voltage upper limit includes:

[0028] When a difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to a set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter;

[0029] When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated until a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as a minimum boost amount of the DC voltage reference value of the photovoltaic inverter.

[0030] Optionally, outputting the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value as a minimum boost amount of the DC voltage reference value of the photovoltaic inverter includes:

[0031] Taking the difference between the new DC voltage adjustment reference value and the initial value of the boost as the boost under the new DC voltage adjustment reference value;

[0032] The improvement amount under the new DC voltage regulation reference value is output as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter.

[0033] Optionally, when a difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit is greater than the error threshold, updating the DC voltage regulation reference value includes:

[0034] When a calculated difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, reducing the initial value of the boost amount by a set voltage threshold to obtain a new boost amount, and updating the DC voltage regulation reference value according to the new boost amount;

[0035] When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by a set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount.

[0036] Optionally, the new lift amount is calculated as follows:

[0037] ΔU dcref =(1+α)ΔU dcref0 ;

[0038] Where,

[0039]

[0040] Among them, ΔU dcref represents the new boost of the photovoltaic inverter; α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref AC side voltage under invmax (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ Lq Indicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 It is the DC voltage reference value of the PV inverter during steady-state operation before the fault.

[0041] Based on the same inventive concept, the present invention also provides a photovoltaic inverter active output capability evaluation system, comprising:

[0042] an AC voltage calculation module, configured to calculate, based on each target grid voltage, an AC side voltage value of a photovoltaic inverter connected to the grid when the grid voltage rises to the target grid voltage;

[0043] A boost calculation module, configured to calculate a minimum boost of a DC voltage reference value of the photovoltaic inverter based on an AC side voltage value of the photovoltaic inverter;

[0044] an active power output module, configured to output an upper limit of active power output of the photovoltaic inverter at the target grid voltage according to a minimum value of an increase in a DC voltage reference value of the photovoltaic inverter;

[0045] The active power evaluation module is used to evaluate the active power output capability of the photovoltaic inverter according to the active power output upper limit of the photovoltaic inverter under the target grid voltages.

[0046] Optionally, the AC voltage calculation module includes:

[0047] a dq current calculation submodule, configured to calculate a d-axis current value and a q-axis current value of a photovoltaic inverter connected to the grid when the grid voltage rises to the target grid voltage;

[0048] an inductor voltage calculation submodule, configured to calculate a filter inductor voltage value of the photovoltaic inverter according to a d-axis current value and a q-axis current value of the photovoltaic inverter;

[0049] The AC voltage output submodule is used to calculate the AC side voltage value of the photovoltaic inverter under the filter inductor voltage according to the filter inductor voltage value of the photovoltaic inverter.

[0050] Optionally, the lift calculation module includes:

[0051] a voltage amplitude comparison submodule, configured to compare the AC side voltage value of the photovoltaic inverter with a pre-acquired upper limit of the output voltage of the photovoltaic inverter when in steady-state operation;

[0052] The boost amount solving submodule is used to calculate the minimum boost amount of the DC voltage reference value of the photovoltaic inverter based on the comparison result of the AC side voltage value and the output voltage upper limit.

[0053] Optionally, the lift calculation submodule includes:

[0054] a zero value adjustment unit, configured to set a minimum value of a DC voltage reference value boost of the photovoltaic inverter to 0 when the AC side voltage value is less than or equal to the output voltage upper limit;

[0055] The minimum value calculation unit is configured to output a minimum value of the DC voltage reference value improvement of the photovoltaic inverter based on a pre-calculated initial value of the improvement when the AC side voltage value is greater than the output voltage upper limit.

[0056] Optionally, the minimum value calculation unit includes:

[0057] A reference value adjustment subunit, configured to obtain a DC voltage adjustment reference value of the photovoltaic inverter according to a pre-calculated initial value of the boost amount;

[0058] a voltage updating subunit, configured to calculate, according to the DC voltage regulation reference value of the photovoltaic inverter, the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value;

[0059] The minimum value output subunit is used to output a minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value.

[0060] Optionally, the minimum value output subunit is specifically used to:

[0061] Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit;

[0062] According to the difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

[0063] Optionally, the minimum value output subunit is specifically used to:

[0064] When a difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to a set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter;

[0065] When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated until a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as a minimum boost amount of the DC voltage reference value of the photovoltaic inverter.

[0066] Optionally, the minimum value output subunit outputs the improvement amount of the photovoltaic inverter under the new DC voltage regulation reference value as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter, specifically for:

[0067] Taking the difference between the new DC voltage adjustment reference value and the initial value of the boost as the boost under the new DC voltage adjustment reference value;

[0068] The improvement amount under the new DC voltage regulation reference value is output as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter.

[0069] Optionally, when a difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit is greater than the error threshold, the minimum value output subunit updates the DC voltage regulation reference value, specifically for:

[0070] When a calculated difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, reducing the initial value of the boost amount by a set voltage threshold to obtain a new boost amount, and updating the DC voltage regulation reference value according to the new boost amount;

[0071] When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by a set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount.

[0072] Optionally, the new lift amount is calculated as follows:

[0073] ΔU dcref =(1+α)ΔU dcref0 ;

[0074] Where,

[0075]

[0076] Among them, ΔU dcref represents the new boost of the photovoltaic inverter; α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref AC side voltage under invmax (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ Lq Indicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 It is the DC voltage reference value of the PV inverter during steady-state operation before the fault.

[0077] In another aspect, the present invention further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0078] The memory is used to store one or more programs;

[0079] When the one or more programs are executed by the at least one processor, the above-mentioned method for evaluating the active output capability of a photovoltaic inverter is implemented.

[0080] In another aspect, the present invention further provides a computer-readable storage medium having an execution program stored thereon. When the execution program is executed, the above-mentioned method for evaluating the active output capability of a photovoltaic inverter is implemented.

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] The present invention provides a method, system, device and medium for evaluating the active output capacity of a photovoltaic inverter, comprising: based on each target grid voltage, when the voltage of the grid is raised to the target grid voltage, calculating the AC side voltage value of the photovoltaic inverter connected to the grid; based on the AC side voltage value of the photovoltaic inverter, calculating the minimum value of the DC voltage reference value increase of the photovoltaic inverter; according to the minimum value of the DC voltage reference value increase of the photovoltaic inverter, outputting the active output upper limit of the photovoltaic inverter at the target grid voltage; according to the active output upper limit of the photovoltaic inverter at each target grid voltage, evaluating the active output capacity of the photovoltaic inverter; the present invention calculates the grid voltage in real time The AC side voltage after voltage rise can accurately capture the impact of grid voltage fluctuations on the inverter output voltage; by calculating the minimum increase in the DC voltage reference value, the photovoltaic inverter can automatically adjust its operating point according to the grid voltage change to maintain the output power to the greatest extent. This process can effectively prevent the DC voltage from being too low or too high due to the grid voltage rise, thereby ensuring the stable operation of the photovoltaic system during high voltage ride-through; and the active output capacity of the photovoltaic inverter is evaluated according to the active output upper limit under different grid voltages. It can quantify the output capacity boundary, clearly understand the performance and stability of the photovoltaic inverter during high voltage ride-through, and provide a data-based basis for the control strategy, thereby improving the active output capacity of the photovoltaic inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 A schematic flow chart of a method for evaluating active output capability of a photovoltaic inverter provided by the present invention;

[0084] Figure 2 A schematic diagram of a process for solving the minimum value of the DC voltage reference value increase in a method for evaluating the active output capability of a photovoltaic inverter provided by the present invention;

[0085] Figure 3 A schematic diagram of the overall framework of a method for evaluating the active output capability of a photovoltaic inverter provided by the present invention;

[0086] Figure 4 A schematic diagram of a simulation model of a single-stage photovoltaic inverter in a method for evaluating the active output capability of a photovoltaic inverter provided by a specific embodiment of the present invention;

[0087] Figure 5A schematic diagram of evaluation results of the active power output capability of a photovoltaic inverter under different working conditions in a method for evaluating the active power output capability of a photovoltaic inverter provided by a specific embodiment of the present invention;

[0088] Figure 6 A schematic diagram of the structure of a photovoltaic inverter active output capability evaluation system provided by the present invention;

[0089] Figure 7 This is a structural diagram of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0090] The present invention provides a method, system, device and medium for evaluating the active output capability of a photovoltaic inverter. Specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0091] Example 1:

[0092] The present invention provides a method for evaluating the active output capability of a photovoltaic inverter, the flow chart of which is as follows: Figure 1 Shown, including:

[0093] Step 1: Based on each target grid voltage, when the grid voltage rises to the target grid voltage, calculate the AC side voltage value of the photovoltaic inverter connected to the grid;

[0094] Step 2: Based on the AC side voltage value of the photovoltaic inverter, calculate the minimum value of the DC voltage reference value increase of the photovoltaic inverter;

[0095] Step 3: Based on the minimum value of the DC voltage reference value increase of the photovoltaic inverter, output the upper limit of the active power output of the photovoltaic inverter under the target grid voltage;

[0096] Step 4: Evaluate the active power output capability of the PV inverter based on the active power output upper limit of the PV inverter at each target grid voltage.

[0097] Generally, because single-stage photovoltaic inverters are directly connected to photovoltaic arrays, they are more susceptible to grid voltage increases during HVRT. This results in the active power output capability of the photovoltaic inverter being constrained by factors such as DC voltage, current limit, voltage modulation ratio, and dynamic reactive power support strategies. This leads to a decrease in active power output capability during HVRT. Conventional technologies typically dynamically adjust reactive power output to maintain grid voltage stability. Alternatively, when the grid voltage rises, the inverter adjusts the DC voltage reference value to adapt to high voltage conditions and avoid output limitations caused by excessively high DC voltage. However, during HVRT, the photovoltaic inverter must prioritize meeting the reactive power support requirements of the grid, sacrificing active power output. Furthermore, if the DC voltage increase is too large, it may exceed the withstand voltage limit of the inverter's DC bus capacitors or power devices, triggering overvoltage protection or even hardware damage. Therefore, to address the aforementioned issues, the present invention considers dynamically calculating the minimum increase in the DC voltage reference value to maximize output power, thereby improving the stability and active support capability of the photovoltaic system during grid faults. Specifically:

[0098] In one implementation, when the grid voltage rises to the target grid voltage in step 1, the process of calculating the AC side voltage value of the photovoltaic inverter connected to the grid may include:

[0099] When the grid voltage rises to the target grid voltage, the d-axis current value and the q-axis current value of the photovoltaic inverter connected to the grid are calculated;

[0100] Calculate the filter inductor voltage value of the photovoltaic inverter based on the d-axis current value and q-axis current value of the photovoltaic inverter;

[0101] According to the filter inductor voltage value of the photovoltaic inverter, calculate the AC side voltage value of the photovoltaic inverter under the filter inductor voltage;

[0102] For example, the calculation formulas for the d-axis current value and the q-axis current value of the photovoltaic inverter connected to the grid can be as follows:

[0103]

[0104] Among them, i′ d Represents the d-axis current value of the photovoltaic inverter; i′ q Indicates the q-axis current value of the photovoltaic inverter; P PV Indicates the active power output of the photovoltaic array; U′ PCC Indicates the grid voltage during a high voltage fault (i.e., the target grid voltage after voltage boost); K Q Indicates the dynamic reactive current proportional coefficient; pu indicates the per-unit value;

[0105] For example, the calculation formula of the filter inductor voltage value of the photovoltaic inverter can be as follows:

[0106]

[0107] Among them, U′ Ld Indicates the d-axis filter inductor voltage value; U′ Lq represents the voltage value of the q-axis filter inductor; ω represents the synchronous electrical angular velocity; L represents the filter inductor;

[0108] For example, the calculation formula for the AC side voltage value of the above photovoltaic inverter under the filter inductor voltage can be as follows:

[0109]

[0110] Among them, U′ inv Indicates the AC side voltage value of the photovoltaic inverter under the filter inductor voltage; U′ PCC Indicates the grid voltage during a high voltage fault;

[0111] In this implementation, when the grid voltage rises to the target value and enters the high voltage ride-through state, the d-axis and q-axis current values ​​are first calculated through normalization based on the active power output and dynamic reactive power support requirements of the photovoltaic array. This process can ensure that the photovoltaic inverter can maintain a reasonable active current distribution while providing necessary reactive power support, and use the inductor voltage equation in the synchronous rotating coordinate system to accurately calculate the voltage drop of the filter inductor on the dq axis. This calculation can fully consider the influence of the grid frequency and filter parameters on the dynamic characteristics of the system; finally, the actual value of the AC side of the photovoltaic inverter is obtained by vector synthesis of the grid voltage and the filter inductor voltage. This series of calculations not only provides an accurate basis for the subsequent optimization and adjustment of the DC voltage reference value, but more importantly, it enables the photovoltaic inverter to quickly evaluate whether its own output voltage exceeds the controllable range when the grid voltage rises abnormally, thereby triggering the calculation mechanism of the minimum DC voltage increase. This method based on real-time calculation of mathematical models can significantly improve the adaptability to grid voltage fluctuations compared to traditional fixed parameter control strategies. Under the premise of ensuring that the inverter does not leave the modulation area, it minimizes unnecessary DC voltage increase and avoids power generation loss caused by the photovoltaic array operating point deviating from the maximum power point.

[0112] After obtaining the AC side voltage value of the PV inverter under HVRT conditions through the above steps, further analysis can be considered to match this voltage amplitude with the normal operating range of the PV inverter to ensure the inverter modulation margin while achieving the optimal power output of the PV system. Specifically:

[0113] In one implementation, the process of calculating the minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the AC side voltage value of the photovoltaic inverter in step 2 may include:

[0114] Compare the AC side voltage value of the photovoltaic inverter with the previously acquired upper limit of the output voltage of the photovoltaic inverter when it is in steady-state operation;

[0115] Based on the comparison result of the AC side voltage value and the output voltage upper limit, the minimum value of the DC voltage reference value increase of the photovoltaic inverter is calculated;

[0116] For example, the expression for the output voltage upper limit of the above photovoltaic inverter in steady-state operation can be as follows:

[0117] U invmax =mU dc ;

[0118] Among them, U invmax Indicates the upper limit of the output voltage of the photovoltaic inverter when it is in steady state operation; U dc Indicates the DC voltage of the photovoltaic inverter in steady-state operation; m represents the preset maximum modulation coefficient, which is determined by the inverter modulation mode;

[0119] The above implementation method can accurately determine the controllability boundary of the inverter under the current grid voltage rise condition by comparing the real-time calculated AC side voltage value with the steady-state output voltage upper limit. When the AC side voltage exceeds the output voltage upper limit determined by the maximum modulation coefficient and the DC voltage, the implementation method dynamically solves the minimum increase in the DC voltage reference value to achieve optimal regulation of the DC side voltage while ensuring that the inverter does not leave the linear modulation area. Therefore, through this implementation method, not only can the excessive increase in DC voltage caused by fixed step adjustment in the traditional method be avoided (which may cause the photovoltaic array operating point to deviate from the maximum power point), but the impact on photovoltaic power generation efficiency can also be reduced by minimizing the DC voltage increment.

[0120] Specifically, in this implementation, the process of calculating the minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the comparison result of the AC side voltage value and the output voltage upper limit may include:

[0121] When the AC side voltage is less than or equal to the output voltage upper limit, the minimum value of the DC voltage reference value boost of the photovoltaic inverter is set to 0;

[0122] When the AC side voltage value is greater than the output voltage upper limit, based on the pre-calculated initial value of the boost, the DC voltage reference value of the output photovoltaic inverter is increased to the minimum value;

[0123] In this specific implementation, by comparing the AC side voltage value U′ of the photovoltaic inverter under the filter inductor voltage inv The output voltage upper limit U invmax The size of U′: inv ≤U invmax , indicating that the voltage rises to U′ PCC After that, the PV inverter can maintain the original DC voltage amplitude unchanged, that is, the DC voltage reference value during the high voltage ride-through period is increased by ΔU dcref The minimum value of U′ is set to 0; if inv >U invmax , indicating that the DC voltage reference value U needs to be increased during the fault period dcref In order to maintain the controllability of the inverter, the DC voltage reference value increase ΔU can be solved. dcref Therefore, by introducing an adaptive regulation mechanism based on voltage threshold determination, this implementation significantly improves the operating efficiency and controllability of PV inverters during high voltage ride-through (HVRD). When the grid voltage rises, causing the AC-side voltage of the PV inverter to exceed the output voltage upper limit determined by the modulation factor and DC voltage, the system accurately identifies this critical state and triggers the calculation process for the minimum increase in the DC voltage reference value. By comparing the AC-side voltage with the output voltage upper limit in real time, dynamic monitoring of the PV inverter's operating status is achieved. Specifically, when the AC-side voltage does not exceed the upper limit, the original DC voltage is maintained, preventing unnecessary voltage increases that could cause the PV array operating point to deviate from the maximum power point. When the voltage exceeds the upper limit, the minimum DC voltage increase that meets the modulation requirements is determined through scientific calculations. This ensures that the PV inverter always operates in the linear modulation region while minimizing redundant increases in the DC-side voltage. This optimization strategy, based on physical models and closed-loop feedback, effectively addresses the power generation efficiency loss caused by blind DC voltage regulation in traditional methods. Furthermore, by minimizing the voltage increase, the electrical stress on the power devices is reduced, enhancing reliability.

[0124] Specifically, in this implementation, the process of outputting the minimum value of the DC voltage reference value boost of the photovoltaic inverter based on the pre-calculated initial value of the boost may include:

[0125] According to the pre-calculated initial value of the boost amount, a DC voltage regulation reference value of the photovoltaic inverter is obtained;

[0126] According to the DC voltage regulation reference value of the photovoltaic inverter, the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value are calculated respectively;

[0127] Based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the minimum value of the DC voltage reference value increase of the output photovoltaic inverter is output;

[0128] In one implementation, the process of obtaining the DC voltage regulation reference value of the photovoltaic inverter based on the pre-calculated initial value of the boost amount may include:

[0129] According to the pre-calculated initial value of the lifting amount (for example, ΔU dcref0 ) and a preset relaxation coefficient (for example, α), calculate the DC voltage reference value increase of the photovoltaic inverter (for example, ΔU dcref express);

[0130] Increase the DC voltage reference value of the photovoltaic inverter by ΔU dcref and the DC voltage reference value in steady-state operation before the fault (for example, U dcref0 The DC voltage regulation reference value of the photovoltaic inverter can be obtained by summing the values ​​(for example, U dcref express);

[0131] For example, the DC voltage reference value increase ΔU of the photovoltaic inverter is dcref The calculation formula can be as follows:

[0132] ΔU dcref =(1+α)ΔU dcref0 ;

[0133] For example, the above pre-calculated initial value of the lifting amount ΔU dcref0 The calculation formula can be as follows:

[0134]

[0135] Among them, U′ PCC Indicates the grid voltage during a high voltage fault; U′ Lq Indicates the q-axis filter inductor voltage value; m represents the preset maximum modulation coefficient, which is determined by the inverter modulation mode; U dcref0 is the DC voltage reference value during steady-state operation before the fault;

[0136] In this specific implementation, by incorporating the grid voltage boost amplitude, q-axis inductor voltage, and maximum modulation coefficient into the calculation of the initial boost value, a reasonable DC voltage regulation starting point can be dynamically generated based on real-time operating conditions, significantly shortening the convergence time of the iterative optimization process. After determining the initial boost value, a closed-loop feedback mechanism performs a secondary verification of the adjusted DC voltage reference value against the AC side voltage and the output voltage upper limit, forming an iterative "calculation-verification-correction" optimization chain. This ensures that the final DC voltage boost value meets the inverter modulation margin requirements while strictly adhering to the minimization principle. This optimization strategy, which combines initial value prediction based on a physical model with closed-loop verification, effectively overcomes the slow convergence speed and susceptibility to local optimality inherent in traditional trial-and-error regulation, significantly improving computational efficiency while maintaining accuracy. Furthermore, by incorporating dynamic parameters such as the q-axis inductor voltage into the initial value calculation, this implementation fully considers the impact of reactive current variations on system voltage characteristics. This allows the boost value calculation to adapt to different operating scenarios under different reactive support strategies, enhancing the robustness of the control system.

[0137] In one implementation, the process of outputting the minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value may include:

[0138] Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit;

[0139] According to the difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the minimum value of the DC voltage reference value boost of the photovoltaic inverter is output using the boost calculation model.

[0140] In this implementation, the process of outputting the minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the difference calculation result between the AC side voltage value and the output voltage upper limit under the DC voltage regulation reference value of the photovoltaic inverter may include:

[0141] When the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter;

[0142] When the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated (according to the formula U dcref =U dcref0 +ΔU dcrefThe voltage regulator updates the voltage at the AC side of the photovoltaic inverter until the difference between the AC side voltage value and the output voltage upper limit under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the increase amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as the minimum increase amount of the DC voltage reference value of the photovoltaic inverter.

[0143] Specifically, the process of outputting the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value as the minimum boost amount of the DC voltage reference value of the photovoltaic inverter may include:

[0144] The difference between the new DC voltage adjustment reference value and the initial value of the boost is used as the boost under the new DC voltage adjustment reference value;

[0145] The increase amount under the new DC voltage regulation reference value is output as the minimum increase amount of the DC voltage reference value of the photovoltaic inverter.

[0146] Specifically, when the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the process of updating the DC voltage regulation reference value may include:

[0147] When the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is reduced by the set voltage threshold to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount;

[0148] When the difference between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by the set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount;

[0149] Increasing the DC voltage through the above implementation method can improve the controllable margin of the photovoltaic inverter. However, the increase of DC voltage will cause the photovoltaic inverter to deviate from the maximum power tracking operating point, affecting the active power output capacity of the photovoltaic inverter. Therefore, it is necessary to perform a DC voltage reference value U during high voltage ride-through. dcref (also the DC voltage regulation reference value) is solved to minimize the increase of DC voltage while ensuring the controllability of photovoltaic inverter. Therefore, a minimum value U of the DC voltage reference value increase during high voltage period is proposed. dcref The solution method is as follows: Figure 2As shown, the DC voltage reference value increase ΔU is obtained by solving dcref In the figure, U dcref0 is the DC voltage reference value in steady-state operation before the fault; ε is the error threshold, which serves as the termination condition of the algorithm iteration; U invmax (U dcref ) is to modify U dcref This implementation dynamically compares the difference between the adjusted AC voltage and the updated output voltage upper limit, combined with a relaxation coefficient adaptive adjustment strategy, to achieve precise iterative optimization of the DC voltage boost. When the AC voltage remains above the upper limit, the system proportionally reduces the boost step size based on the voltage difference derived from the physical model, avoiding the overshoot caused by traditional fixed-step regulation. When the voltage returns to the controllable range, the boost step size is gradually increased to achieve rapid convergence. This bidirectional regulation mechanism ensures that the inverter always operates within the linear modulation region while strictly adhering to the principle of minimum DC voltage boost, keeping the PV array operating point as close to the maximum power point as possible, significantly reducing power generation losses caused by redundant DC voltage boost. Furthermore, by introducing an error threshold ε as the iteration termination condition, a balance is achieved between computational accuracy and efficiency, avoiding the risk of control failure caused by premature termination and preventing system response delays caused by excessive iterations.

[0150] For example, the calculation formula of the new lifting amount can be as follows:

[0151] ΔU fcref =(1+α)ΔU dcref0 ;

[0152] Where,

[0153]

[0154] Among them, ΔU dcref represents the new boost of the photovoltaic inverter (also expressed as the boost of the DC voltage reference value of the photovoltaic inverter); α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref AC side voltage under invmax (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ LqIndicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 is the DC voltage reference value of the PV inverter in steady-state operation before the fault. In this example, the relaxation coefficient α is introduced to adjust the iteration step size. When the AC side voltage U′ inv and the upper limit of the AC side voltage U' invmax When the difference is large, the relaxation coefficient α is large, and the adjustment step of the DC voltage reference value is large; when the values ​​of the two are close, the relaxation coefficient α is small, and the adjustment step of the DC voltage reference value is small, U′ inv (U dcref ) and U′ invmax (U dcref ) needs to be recalculated according to the DC voltage reference value that changes during each iterative calculation. This example dynamically calculates the relaxation coefficient α based on the real-time deviation between the AC side voltage and the output voltage upper limit, and constructs an iterative adjustment model with adaptive step size: when the voltage deviation is large, rapid coarse adjustment is achieved by increasing the α value, which significantly shortens the convergence time; when the voltage approaches the threshold, the α value is automatically reduced for fine adjustment, effectively avoiding overshoot oscillation. This nonlinear adjustment strategy can not only overcome the shortcomings of the traditional fixed step size algorithm, such as slow convergence speed and easy oscillation, but also dynamically associate the electrical parameter U′ inv , U′ invmax The iterative update of the DC voltage reference value ensures the physical rationality and adaptability of each adjustment step to the working conditions. More importantly, by incorporating dynamic parameters such as the q-axis inductor voltage and the grid lift voltage into the relaxation coefficient calculation, the adjustment process can respond in real time to the impact of changes in the reactive support strategy on the system voltage characteristics, thereby enhancing the algorithm's adaptability to complex grid fault scenarios. At the engineering application level, this implementation method minimizes the DC voltage boost and controls the offset amplitude of the photovoltaic array operating point to an extremely low level, significantly reducing the loss of photovoltaic system power generation efficiency during high voltage ride-through. At the same time, precise voltage closed-loop control is used to ensure that the inverter always operates in a safe modulation area, while simultaneously reducing the risk of overvoltage breakdown of power devices.

[0155] In one implementation, the DC voltage reference value is increased according to the calculated value ΔU dcref The minimum value of is used as the final DC voltage reference value increase amount. Specifically, in step 3 above, the process of outputting the upper limit of the active power output of the photovoltaic inverter under the target grid voltage according to the minimum value of the DC voltage reference value increase amount of the photovoltaic inverter may include:

[0156] According to the minimum value of the DC voltage reference value increase of the photovoltaic inverter and the updated DC voltage reference value (that is, the DC voltage adjustment reference value mentioned above), the output power of the photovoltaic inverter is solved by the photovoltaic cell PU curve to obtain the grid voltage U corresponding to this time. P ' CCThe photovoltaic active output upper limit increases the grid voltage U P ' CC Then, continue to solve and calculate according to steps 1 to 3 to obtain the upper limit of photovoltaic active power output corresponding to different target grid voltages;

[0157] In this implementation, the PU curve of the photovoltaic cell is traced back and the maximum output power of the corresponding operating point is solved in real time in combination with the adjusted DC voltage reference value, thereby accurately characterizing the upper limit of active output under a specific grid voltage rise amplitude; by systematically traversing different target grid voltage scenarios and iteratively executing the calculation process, a complete characteristic curve of the active output capacity of the photovoltaic inverter changing with the grid voltage is finally constructed. This evaluation method based on the deep integration of physical models and operating data not only reveals the impact of DC voltage regulation on photovoltaic power generation efficiency during high voltage ride-through, but also provides a quantitative basis for the optimization of inverter control parameters.

[0158] In summary, the present invention addresses the problem in the prior art that due to the lack of a dynamic quantitative evaluation method for the active output capability of a photovoltaic inverter during high voltage ride-through, the control strategy cannot adaptively adjust the DC voltage reference value according to the grid voltage rise amplitude, resulting in limited active output capability. A method for evaluating the active output capability of a photovoltaic inverter is proposed, such as Figure 3 As shown in the figure, first, by setting the initial amplitude of the voltage boost and judging whether the DC voltage of the single-stage photovoltaic inverter can be maintained unchanged, the minimum boost amount of the DC voltage reference value required by the inverter is further calculated. The calculation of this boost amount ensures that the inverter can adjust its DC voltage reference value when the grid voltage increases to maintain stable operation. Based on this minimum boost amount, the active output upper limit of the inverter under the target grid voltage is calculated. This is the maximum stable power that the inverter can output under high voltage conditions. Finally, the active output capacity of the inverter is evaluated based on the active output upper limit under different grid voltage conditions (taking the voltage boost amplitude of less than 1.3pu as an example in the figure) to ensure that the inverter can maintain continuous and stable power output when the grid voltage fluctuates, thereby optimizing the design and operation performance of the photovoltaic system. This is of great significance for optimizing the inverter control parameters and improving the active support capability of the photovoltaic system during grid faults.

[0159] Example 2:

[0160] like Figure 4As shown, by building a single-stage photovoltaic inverter grid-connected model, the execution process of a photovoltaic inverter active output capacity evaluation method provided by the present invention is specifically described, wherein the model simulation parameter information includes: rated power = 250kW, filter inductance L1 = 0.014956mH, DC rated voltage 540V, filter inductance L2 = 0.0059825mH, AC rated voltage 280V, filter capacitor C1 = 0.001F, system rated frequency 50Hz, inverter modulation carrier frequency 1650Hz, DC bus capacitor C = 0.0257F; irradiance 1000W / m 2 ; Temperature 25℃; The main components of the simulation model include: photovoltaic array, inverter, filter, in the figure, I PV Represents photovoltaic current; U PV Indicates photovoltaic voltage; U dc Indicates DC voltage; i a、 i b、 i c Represent the three-phase current respectively;

[0161] Set the model to run in two working conditions:

[0162] Working condition 1: Dynamic reactive current proportional coefficient K Q =0;

[0163] Working condition 2: Dynamic reactive current proportional coefficient K Q =1.5.

[0164] The grid voltage rise amplitude is set to start at 1.1 pu and increase in steps of 0.1 pu until it reaches 1.3 pu. Each grid voltage rise amplitude is solved according to steps 1 to 3 in the embodiment. The final evaluation result is as follows: Figure 5 As shown, according to the evaluation result diagram, it can be explained that the present invention provides a photovoltaic inverter active output capacity evaluation method, which can effectively improve the active output capacity of the photovoltaic inverter during high voltage ride-through by dynamically adjusting the control strategy of the photovoltaic inverter, enhance its stability when the grid voltage fluctuates, and reduce power output loss, thereby improving the adaptability and stability of the photovoltaic system under abnormal grid conditions.

[0165] Example 3:

[0166] Based on the same inventive concept, the present invention also provides a photovoltaic inverter active output capability evaluation system, the structural composition diagram is as follows: Figure 6 Shown, including:

[0167] An AC voltage calculation module is used to calculate the AC side voltage value of the photovoltaic inverter connected to the grid when the grid voltage is raised to the target grid voltage based on each target grid voltage;

[0168] The boost calculation module is used to solve the minimum boost of the DC voltage reference value of the photovoltaic inverter based on the AC side voltage value of the photovoltaic inverter using a pre-built boost calculation model;

[0169] The active power output module is used to output the upper limit of the active power output of the photovoltaic inverter under the target grid voltage according to the minimum value of the DC voltage reference value increase of the photovoltaic inverter;

[0170] The active power evaluation module is used to evaluate the active power output capability of the photovoltaic inverter according to the active power output upper limit of the photovoltaic inverter under each target grid voltage.

[0171] In one implementation, the AC voltage calculation module may include:

[0172] The dq current calculation submodule is used to calculate the d-axis current value and the q-axis current value of the photovoltaic inverter connected to the grid when the grid voltage rises to the target grid voltage;

[0173] The inductor voltage calculation submodule is used to calculate the filter inductor voltage value of the photovoltaic inverter according to the d-axis current value and the q-axis current value of the photovoltaic inverter;

[0174] The AC voltage output submodule is used to calculate the AC side voltage value of the photovoltaic inverter under the filter inductor voltage according to the filter inductor voltage value of the photovoltaic inverter.

[0175] In one implementation, the lift calculation module may include:

[0176] The voltage amplitude comparison submodule is used to compare the AC side voltage value of the photovoltaic inverter with the pre-acquired output voltage upper limit of the photovoltaic inverter in steady-state operation;

[0177] The boost calculation submodule is used to calculate the minimum boost of the DC voltage reference value of the photovoltaic inverter based on the comparison result of the AC side voltage value and the output voltage upper limit using a pre-built boost calculation model.

[0178] In this implementation, the lift calculation submodule may include:

[0179] The zero value adjustment unit is used to set the minimum value of the DC voltage reference value boost of the photovoltaic inverter to 0 when the AC side voltage value is less than or equal to the output voltage upper limit;

[0180] The minimum value calculation unit is used to output the minimum value of the DC voltage reference value boost of the photovoltaic inverter based on the pre-calculated initial value of the boost and using a pre-built boost calculation model when the AC side voltage value is greater than the output voltage upper limit.

[0181] In this implementation, the minimum value calculation unit may include:

[0182] The reference value adjustment subunit is used to obtain a DC voltage adjustment reference value of the photovoltaic inverter according to a pre-calculated initial value of the boost amount;

[0183] The voltage update subunit is used to calculate the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value according to the DC voltage regulation reference value of the photovoltaic inverter;

[0184] The minimum value output subunit is used to output the minimum value of the DC voltage reference value boost of the photovoltaic inverter based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value and using the boost calculation model.

[0185] In this implementation, the minimum value output subunit can be used to:

[0186] Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit;

[0187] According to the difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the minimum value of the DC voltage reference value boost of the photovoltaic inverter is output using the boost calculation model.

[0188] In this implementation, the minimum value output subunit can be used to:

[0189] When the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter;

[0190] When the difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated until the difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the increase amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as the minimum increase amount of the DC voltage reference value of the photovoltaic inverter.

[0191] In this implementation, the minimum value output subunit can be used to:

[0192] When the difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is reduced by the set voltage threshold to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount;

[0193] When the difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by the set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount.

[0194] For example, the calculation formula of the new lifting amount can be as follows:

[0195] ΔU dcref =(1+α)ΔU dcref0 ;

[0196] Where,

[0197]

[0198] Among them, ΔU dcref represents the new boost of the photovoltaic inverter; α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref AC side voltage under onvmax (U dcref ) represents the PV inverter's DC voltage regulation reference value U dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ Lq Indicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 It is the DC voltage reference value of the PV inverter during steady-state operation before the fault.

[0199] Example 4:

[0200] like Figure 7As shown, the present invention also provides an electronic device, which may be a computer, a single-chip microcomputer, a smart mobile device, or the like. The electronic device in this embodiment may include a processor, a memory, a transceiver component, and the like. The memory, processor, and transceiver component are connected via a bus; the memory may be used to store an execution program, which may include instructions; and the processor may be used to execute the instructions stored in the memory. The memory may also be used to store data, which may be accessed and / or modified during the execution of the instructions.

[0201] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a method for evaluating the active output capacity of a photovoltaic inverter in the above embodiment.

[0202] Example 5:

[0203] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a method for evaluating the active output capacity of a photovoltaic inverter in the above embodiment.

[0204] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0205] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0206] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0207] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0208] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art may still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims.

Claims

1. A method for evaluating active output capability of a photovoltaic inverter, characterized in that: include: Based on each target grid voltage, when the grid voltage rises to the target grid voltage, calculating an AC side voltage value of a photovoltaic inverter connected to the grid; Calculating a minimum value of an increase in a DC voltage reference value of the photovoltaic inverter based on an AC side voltage value of the photovoltaic inverter; outputting an upper limit of active power output of the photovoltaic inverter at the target grid voltage according to a minimum value of the DC voltage reference value increase of the photovoltaic inverter; The active power output capability of the photovoltaic inverter is evaluated according to the active power output upper limit of the photovoltaic inverter at each target grid voltage.

2. The method according to claim 1, wherein When the voltage of the grid rises to the target grid voltage, calculating the AC side voltage value of the photovoltaic inverter connected to the grid includes: When the voltage of the grid rises to the target grid voltage, calculating a d-axis current value and a q-axis current value of a photovoltaic inverter connected to the grid; Calculating a filter inductor voltage value of the photovoltaic inverter according to a d-axis current value and a q-axis current value of the photovoltaic inverter; According to the filter inductor voltage value of the photovoltaic inverter, an AC side voltage value of the photovoltaic inverter under the filter inductor voltage is calculated.

3. The method according to claim 1, wherein The step of calculating the minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the AC side voltage value of the photovoltaic inverter includes: comparing the AC side voltage value of the photovoltaic inverter with a pre-acquired upper limit of the output voltage of the photovoltaic inverter when in steady-state operation; Based on the comparison result of the AC side voltage value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is calculated.

4. The method according to claim 3, wherein The calculating, based on the comparison result of the AC side voltage value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter includes: When the AC side voltage value is less than or equal to the output voltage upper limit, setting the minimum value of the DC voltage reference value increase of the photovoltaic inverter to 0; When the AC side voltage value is greater than the output voltage upper limit, a minimum value of the DC voltage reference value boost of the photovoltaic inverter is calculated based on a pre-calculated initial value of the boost.

5. The method according to claim 4, wherein The step of calculating the minimum value of the DC voltage reference value boost of the photovoltaic inverter based on the pre-calculated initial value of the boost comprises: Obtaining a DC voltage regulation reference value of the photovoltaic inverter according to a pre-calculated initial value of the boost amount; According to the DC voltage regulation reference value of the photovoltaic inverter, respectively calculating the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value; Based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

6. The method according to claim 5, wherein The step of outputting a minimum value of an increase in the DC voltage reference value of the photovoltaic inverter based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value includes: Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit; According to the difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

7. The method according to claim 6, wherein Outputting a minimum value of the DC voltage reference value increase of the photovoltaic inverter according to a difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit includes: When a difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to a set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter; When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated until a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as a minimum boost amount of the DC voltage reference value of the photovoltaic inverter.

8. The method according to claim 7, wherein Outputting the improvement amount of the photovoltaic inverter under the new DC voltage regulation reference value as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter includes: Taking the difference between the new DC voltage adjustment reference value and the initial value of the boost as the boost under the new DC voltage adjustment reference value; The improvement amount under the new DC voltage regulation reference value is output as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter.

9. The method according to claim 7, wherein When a difference calculation result between an AC side voltage value and an output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, updating the DC voltage regulation reference value includes: When a calculated difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, reducing the initial value of the boost amount by a set voltage threshold to obtain a new boost amount, and updating the DC voltage regulation reference value according to the new boost amount; When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by a set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount.

10. The method according to claim 9, wherein The new lift calculation formula is as follows: D.U. dcref =(1+α)ΔU dcref0 ; Where, Among them, ΔU dcref represents the new boost of the photovoltaic inverter; α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the DC voltage regulation reference value U of the photovoltaic inverter dcref AC side voltage under invmax (U dcref ) represents the DC voltage regulation reference value U of the photovoltaic inverter dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ Lq Indicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 It is the DC voltage reference value of the PV inverter during steady-state operation before the fault.

11. A photovoltaic inverter active output capability evaluation system, characterized in that: include: an AC voltage calculation module, configured to calculate, based on each target grid voltage, an AC side voltage value of a photovoltaic inverter connected to the grid when the grid voltage rises to the target grid voltage; A boost calculation module, configured to calculate a minimum boost of a DC voltage reference value of the photovoltaic inverter based on an AC side voltage value of the photovoltaic inverter; an active power output module, configured to output an upper limit of active power output of the photovoltaic inverter at the target grid voltage according to a minimum value of an increase in a DC voltage reference value of the photovoltaic inverter; The active power evaluation module is used to evaluate the active power output capability of the photovoltaic inverter according to the active power output upper limit of the photovoltaic inverter under the target grid voltages.

12. The system according to claim 11, wherein The AC voltage calculation module includes: a dq current calculation submodule, configured to calculate a d-axis current value and a q-axis current value of a photovoltaic inverter connected to the grid when the grid voltage rises to the target grid voltage; an inductor voltage calculation submodule, configured to calculate a filter inductor voltage value of the photovoltaic inverter according to a d-axis current value and a q-axis current value of the photovoltaic inverter; The AC voltage output submodule is used to calculate the AC side voltage value of the photovoltaic inverter under the filter inductor voltage according to the filter inductor voltage value of the photovoltaic inverter.

13. The system according to claim 11, wherein: The lift calculation module includes: a voltage amplitude comparison submodule, configured to compare the AC side voltage value of the photovoltaic inverter with a pre-acquired upper limit of the output voltage of the photovoltaic inverter when in steady-state operation; The boost amount solving submodule is used to calculate the minimum boost amount of the DC voltage reference value of the photovoltaic inverter based on the comparison result of the AC side voltage value and the output voltage upper limit.

14. The system according to claim 13, wherein: The lift solving submodule includes: a zero value adjustment unit, configured to set a minimum value of a DC voltage reference value boost of the photovoltaic inverter to 0 when the AC side voltage value is less than or equal to the output voltage upper limit; The minimum value calculation unit is configured to output a minimum value of the DC voltage reference value improvement of the photovoltaic inverter based on a pre-calculated initial value of the improvement when the AC side voltage value is greater than the output voltage upper limit.

15. The system according to claim 14, wherein: The minimum value calculation unit includes: A reference value adjustment subunit, configured to obtain a DC voltage adjustment reference value of the photovoltaic inverter according to a pre-calculated initial value of the boost amount; a voltage updating subunit, configured to calculate, according to the DC voltage regulation reference value of the photovoltaic inverter, the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value; The minimum value output subunit is used to output a minimum value of the DC voltage reference value increase of the photovoltaic inverter based on the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value.

16. The system according to claim 15, wherein: The minimum value output subunit is specifically used for: Performing a difference calculation on the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit; According to the difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit, a minimum value of the DC voltage reference value increase of the photovoltaic inverter is output.

17. The system according to claim 16, wherein: The minimum value output subunit is specifically used for: When a difference calculation result between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to a set error threshold, the initial value of the boost amount is output as the minimum value of the DC voltage reference value boost amount of the photovoltaic inverter; When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, the DC voltage regulation reference value is updated until a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the new DC voltage regulation reference value is less than or equal to the set error threshold, and the boost amount of the photovoltaic inverter under the new DC voltage regulation reference value is output as a minimum boost amount of the DC voltage reference value of the photovoltaic inverter.

18. The system according to claim 17, wherein: The minimum value output subunit outputs the improvement amount of the photovoltaic inverter under the new DC voltage regulation reference value as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter, specifically for: Taking the difference between the new DC voltage adjustment reference value and the initial value of the boost as the boost under the new DC voltage adjustment reference value; The improvement amount under the new DC voltage regulation reference value is output as the minimum improvement amount of the DC voltage reference value of the photovoltaic inverter.

19. The system of claim 17, wherein: The minimum value output subunit updates the DC voltage regulation reference value when a difference calculation result between the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value and the output voltage upper limit is greater than the error threshold, specifically for: When a calculated difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is greater than the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, reducing the initial value of the boost amount by a set voltage threshold to obtain a new boost amount, and updating the DC voltage regulation reference value according to the new boost amount; When a calculation result of a difference between the AC side voltage value and the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value is greater than the error threshold, and the AC side voltage value of the photovoltaic inverter under the DC voltage regulation reference value is less than or equal to the output voltage upper limit of the photovoltaic inverter under the DC voltage regulation reference value, the initial value of the boost amount is increased by a set voltage value to obtain a new boost amount, and the DC voltage regulation reference value is updated according to the new boost amount.

20. The system of claim 19, wherein: The new lift calculation formula is as follows: D.U. dcref =(1+α)ΔU dcref0 ; Where, Among them, ΔU dcref represents the new boost of the photovoltaic inverter; α represents the relaxation coefficient; ΔU dcref0 Indicates the initial value of the photovoltaic inverter's boost; U dcref Indicates the DC voltage regulation reference value of the photovoltaic inverter; U′ inv (U dcref ) represents the DC voltage regulation reference value U of the photovoltaic inverter dcref AC side voltage under invmax (U dcref ) represents the DC voltage regulation reference value U of the photovoltaic inverter dcref The upper limit of the output voltage under PCC Indicates the target grid voltage after voltage boost; U′ Lq Indicates the voltage value of the q-axis filter inductor; m indicates the preset maximum modulation coefficient; U dcref0 It is the DC voltage reference value of the PV inverter during steady-state operation before the fault.

21. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a method for evaluating active output capability of a photovoltaic inverter according to any one of claims 1 to 10 is implemented.

22. A computing device readable storage medium, characterized in that An execution program is stored thereon, and when the execution program is executed, a method for evaluating the active output capability of a photovoltaic inverter according to any one of claims 1 to 10 is implemented.

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