A loop parameter adaptive adjustment method, energy storage aging test system and medium

Abstract

The application provides a loop parameter adaptive adjustment method, an energy storage aging test system and a medium. The loop parameter adaptive adjustment method is applied to the energy storage aging test system, the energy storage aging test system comprises at least two inverters, and the method comprises the following steps: controlling an inverter serving as a power grid end and another inverter serving as a load end to be phase-locked and networked; acquiring a first voltage instantaneous value of the inverter serving as the power grid end and a second voltage instantaneous value of a networked port of the inverter serving as the load end; and based on an accumulated voltage error value of the first voltage instantaneous value and the second voltage instantaneous value in a preset statistical period, adaptively adjusting parameters of a current loop at the networked port of the inverter serving as the load end. The application scheme can realize adaptive adjustment of the current loop parameters of the inverter serving as the load end, realize dynamic optimization of control parameters in the aging test process, and be beneficial to ensuring the stability and accuracy of the aging test.

Description

Technical Field

[0001] This invention belongs to the field of inverter aging detection technology, and particularly relates to a loop parameter adaptive adjustment method, an energy storage aging test system, and a medium. Background Technology

[0002] Energy storage inverters typically undergo aging tests before leaving the factory to verify their stability and reliability under long-term operating conditions. In actual production testing, to improve testing efficiency and reduce energy consumption, an inverter-to-load aging test is usually conducted. This involves connecting at least two inverters together, with one inverter simulating grid operation and the other acting as a load. This creates an energy cycle within the system, enabling high-load operation testing of the inverters.

[0003] In the aforementioned grid-connected test, one inverter serves as the grid-side voltage reference, while the other inverter acts as the load, connected to the simulated grid and absorbing power. However, due to differences between the aging test environment and the actual grid-connected operating environment—for example, the electrical characteristics of the simulated grid differ from those of the real grid—the current loop control parameters used by the inverter in actual operation may not be applicable in the grid-connected test scenario. In the aging test, if the PI parameter of the inverter's current loop is a fixed value, using the same PI parameter across all power levels and the entire power frequency cycle, it can easily lead to a decline in the grid-connected current control performance. This includes increased output current fluctuations, increased voltage deviation, and reduced power response accuracy, thus affecting the stability of the inverter's aging test and the accuracy of the test results. Summary of the Invention

[0004] One objective of this invention is to provide an adaptive adjustment of the inverter's current loop control parameters based on the system's operating status during the aging test of an energy storage inverter, so as to ensure the stability and accuracy of the aging test process.

[0005] According to a first aspect of the present invention, a loop parameter adaptive adjustment method is provided, applied to an energy storage aging test system, the energy storage aging test system comprising at least two inverters, the method comprising:

[0006] The inverter acting as the grid end and the other inverter acting as the load end are controlled to perform phase-locked grid connection;

[0007] Obtain the first instantaneous voltage value of the inverter that acts as the grid end and the second instantaneous voltage value of the inverter that acts as the load end;

[0008] Based on the cumulative voltage error between the first and second instantaneous voltage values ​​within a preset statistical period, the parameters of the current loop at the grid connection port of the inverter, which acts as the load, are adaptively adjusted.

[0009] In some possible embodiments, based on the cumulative voltage error between the first instantaneous voltage value and the second instantaneous voltage value within a preset statistical period, the parameters of the current loop at the grid connection port of the inverter, which acts as the load, are adjusted, including:

[0010] The preset statistical period is divided into multiple angle intervals and the number of voltage samplings in each angle interval is determined.

[0011] Based on the first instantaneous voltage value and the second instantaneous voltage value of the sampling number of times within each angle interval, the average voltage value of each angle interval is calculated;

[0012] The voltage weighting coefficient for each angle interval is determined based on the sum of the average voltage values ​​of the multiple angle intervals and the average voltage value of each angle interval.

[0013] The cumulative voltage error value is obtained by weighting and summing the voltage weighting coefficients for each angle interval and the voltage deviation between the first and second instantaneous voltage values ​​for each angle interval.

[0014] Based on the relationship between the cumulative voltage error value and the preset error threshold, the parameters of the current loop at the grid connection port are adaptively adjusted.

[0015] In some possible embodiments, the preset error threshold is the product of the cumulative value of the first instantaneous voltage value within the preset statistical period and the first proportional coefficient.

[0016] In some possible embodiments, based on the relationship between the accumulated voltage error value and a preset error threshold, the parameters of the current loop at the grid connection port are adaptively adjusted, including:

[0017] When the cumulative voltage error value is greater than the preset error threshold, the loop parameter adjustment value of the current loop is determined based on the current loop parameter value at the current moment and the adjustment step size determined based on the initial parameters.

[0018] When the cumulative voltage error value is less than or equal to the preset error threshold, the loop parameter adjustment value of the current loop is determined according to the relationship between the current loop parameter value at the current moment and the initial parameter;

[0019] The initial parameters include the initial proportional parameters and initial integral parameters of the current loop.

[0020] In some possible embodiments, the adjustment step size determined based on the initial parameters includes:

[0021] Obtain the initial proportional parameters and initial integral parameters of the current loop;

[0022] Based on the product of the initial proportional parameter and the second proportional coefficient, a first adjustment step size for adjusting the proportional parameter of the current loop is determined;

[0023] Based on the product of the initial integral parameter and the third proportional coefficient, a second adjustment step size for adjusting the integral parameter of the current loop is determined.

[0024] In some possible embodiments, the loop parameter adjustment value of the current loop is determined based on the relationship between the current loop parameter value at the current moment and the initial parameter, including:

[0025] When the loop parameter value at the current moment is less than the initial parameter, the sum of the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value;

[0026] When the loop parameter value at the current moment is greater than the initial parameter, the difference between the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value;

[0027] When the loop parameter at the current moment is equal to the initial parameter, the adjusted value of the loop parameter is determined to be the initial parameter.

[0028] In some possible embodiments, obtaining a first instantaneous voltage value of the inverter acting as the grid end and a second instantaneous voltage value of the inverter's grid connection port acting as the load end includes:

[0029] The first instantaneous voltage value is determined based on the effective value of the target voltage of the inverter acting as the grid end and the synchronization angle after phase-locked connection.

[0030] The voltage of the inverter's grid connection, which acts as the load, is sampled to obtain the instantaneous value of the second voltage.

[0031] In some possible embodiments, controlling one inverter acting as the grid end and the other inverter acting as the load end to perform phase-locked grid connection includes:

[0032] At a preset grid angle, the inverter acting as the grid end sends a preset level signal to the inverter acting as the load end via its IO pin.

[0033] The inverter acting as the grid end and the inverter acting as the load end are controlled to perform phase-locked grid connection.

[0034] According to a second aspect of the present invention, an energy storage aging test system is provided, the energy storage aging test system comprising:

[0035] At least two inverters, each of which includes an off-grid port, a grid-connected port, and I / O pins;

[0036] At least one switch, each of the switches being used to connect the off-grid port of one inverter to the grid-connected port of another inverter, wherein the inverter connected to the off-grid port by the switch acts as the grid end and the inverter connected to the grid-connected port by the switch acts as the load end;

[0037] The control unit is communicatively connected to the inverter and the switch. The control unit is used to control the switching on and off, and to perform the loop parameter adaptive adjustment method as described above when the inverter is subjected to aging test.

[0038] According to a third aspect of the present invention, a computer storage medium is provided, the computer storage medium being capable of storing program instructions, which, when executed by a processor, can implement the loop parameter adaptive adjustment method as described above.

[0039] According to the present invention, by controlling the inverter acting as the grid end and the inverter acting as the load end to be connected in phase-locked loop, the two inverters form a stable counter-operation relationship during the aging test. This allows for the synchronous acquisition of the instantaneous voltage values ​​of both inverters and the statistical calculation of the cumulative voltage error value. Based on the cumulative voltage error value, the current loop parameters at the grid connection port of the load-end inverter are adaptively adjusted. In other words, the circuit loop parameters are dynamically adjusted according to the actual situation of each inverter during the aging test, which helps to ensure the stability and accuracy of the aging test.

[0040] Furthermore, by dividing the preset statistical period into multiple angle intervals and introducing voltage weighting coefficients for partitioned weighted statistics, errors at different phase positions can be differentiated and evaluated, thereby improving the calculation accuracy of the cumulative voltage error value. Simultaneously, by setting an error threshold related to the cumulative voltage of the preset period, the error judgment can adaptively change, thus avoiding the risk of misjudgment caused by a fixed threshold. In addition, by determining the adjustment step size based on initial parameters and reducing the adjustment when the error exceeds the threshold, and reverting to the initial parameter direction when the error falls back, the current loop parameters are dynamically converged within a stable range, thereby suppressing current oscillations and waveform distortion, and improving the reliability and consistency of the entire aging test process.

[0041] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0042] Figure 1 A structural diagram of an energy storage aging test system according to an embodiment of the present invention is shown;

[0043] Figure 2 A schematic flowchart of a loop parameter adaptive adjustment method according to an embodiment of the present invention is shown;

[0044] Figure 3 It shows Figure 2 A schematic flowchart of step S100 is shown;

[0045] Figure 4 It shows Figure 2 A schematic flowchart of the method for step S200 shown;

[0046] Figure 5 It shows Figure 2 A schematic flowchart of step S300 is shown;

[0047] Figure 6 It shows Figure 5 A schematic flowchart of step S305. Detailed Implementation

[0048] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0049] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0050] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0051] Figure 1 A structural diagram of an energy storage aging test system according to an embodiment of the present invention is shown. Figure 1 As shown, the energy storage aging test system includes at least two inverters, at least one switch, and a control unit. Each inverter includes an off-grid port, a grid-connected port, and I / O pins for signal interaction. Each switch connects the off-grid port of one inverter to the grid-connected port of another inverter, forming a peer-to-peer connection between the two inverters. The control unit communicatively connects the inverters and the switch, controlling the on / off state of the switch to electrically connect the off-grid port of one inverter to the grid-connected port of the other inverter. The inverter with its off-grid port on acts as the grid end, and the inverter with its grid-connected port on acts as the load end. Furthermore, the control unit executes an adaptive loop parameter adjustment method during the aging test of the inverters.

[0052] During the aging test, by controlling the conduction state of the control switch, one inverter's off-grid port outputs AC voltage to the system and acts as the grid end to simulate the grid operating environment, while the other inverter's grid-connected port is connected to the simulated grid and acts as the load end. This creates an energy loop between the two inverters and forms a tandem operation structure. The grid-connected inverter outputs AC voltage signals in off-grid operation mode, and the two inverters can interact via I / O pins to achieve phase-locked grid connection and synchronous operation. It is important to understand that during the aging test, all inverters are in an off-grid state, meaning they are not electrically connected to the public grid. The "off-grid operation mode" and "grid-connected operation mode" mentioned above refer to the inverter's control modes. Off-grid operation mode means the inverter operates as a voltage source and outputs AC voltage signals to form a simulated grid. Grid-connected operation mode means the inverter operates in connection with the simulated grid, electrically connected to the simulated grid through the grid-connected port, and adjusts power according to control commands.

[0053] exist Figure 1In the illustrated embodiment, the control unit can be, but is not limited to, a PC host computer. The energy storage aging test system includes two inverters: a first inverter and a second inverter. The first inverter has an input IO pin In_1, an output IO pin Out_1, a first grid-connected port, and a first off-grid port. The second inverter has an input IO pin In_2, an output IO pin Out_2, a second grid-connected port, and a second off-grid port. The output IO pin Out_1 is electrically connected to the input IO pin In_2, and the input IO pin In_1 is electrically connected to the output IO pin Out_2, used to transmit synchronization signals between the two inverters. The two inverters are electrically connected via the first off-grid port and the second grid-connected port to form a parallel operation structure. One inverter outputs AC voltage through the first off-grid port to form a simulated power grid and acts as the grid terminal, while the other inverter is connected to the simulated power grid through the second grid-connected port and acts as the load terminal, thereby forming an energy cycle between the two inverters.

[0054] The energy storage aging test system also includes a DC power supply. The PC host computer establishes communication connections with the DC power supply, inverter 1, and inverter 2 via RS485 communication interfaces. Specifically, the PC host computer communicates with the DC power supply via RS485-2 interface, with one of the inverters via RS485-1 interface, and with the other inverter via RS485-3 interface, and is used to send control commands to each device and obtain operating data.

[0055] Figure 2 A schematic flowchart of a loop parameter adaptive adjustment method according to an embodiment of the present invention is shown, which is applied to the above-described energy storage aging test system. The loop parameter adaptive adjustment method includes the following steps S100 to S300.

[0056] Step S100: Control one inverter acting as the grid end and another inverter acting as the load end to perform phase-locked grid connection.

[0057] exist Figure 1 In the illustrated embodiment, by controlling relay J1 to engage and relay J2 to disengage, the first inverter is placed in off-grid operation mode. Simultaneously, by controlling relay J3 to disengage and relay J4 to engage, the second inverter is placed in grid-connected operation mode. Thus, the first inverter operates as the grid-side device, and the second inverter operates as the load-side device. It is understood that under different testing requirements, the roles of the grid-side and load-side devices can be interchanged. By adjusting the conduction state of the relays, the second inverter can operate as the grid-side device, while the first inverter operates as the load-side device.

[0058] Figure 3 It shows Figure 2The diagram shows a schematic flowchart of the method for phase-locked grid connection of the inverter in step S100. Figure 3 As shown, step S100 may include steps S101 to S102.

[0059] Step S101: At the preset grid angle, control the IO pin of the inverter acting as the grid end to send a preset level signal to the IO pin of the inverter acting as the load end.

[0060] The inverter acting as the grid-side outputs an AC voltage signal in off-grid operation mode and updates the voltage angle according to the operating frequency of the control system, causing the voltage angle to cycle within the range of 0-2π. When the off-grid voltage angle of the inverter acting as the grid-side reaches the preset grid angle, it sends a preset level signal to the inverter acting as the load side through its output IO pin to indicate the current phase position of the grid voltage. The preset grid angle is a pre-set voltage phase angle position used as a trigger reference for phase synchronization between the two inverters. The preset level can be high or low, indicating that the phase has reached the preset grid angle. This invention does not limit the specific value of the preset grid angle or the specific form of the preset level.

[0061] Step S102: Control the inverter acting as the grid end and the inverter acting as the load end to perform phase-locked grid connection.

[0062] In one embodiment, the preset grid angle is π / 6 or 2π. When the voltage angle of the first inverter (as the grid-side inverter) reaches π / 6, the control output IO pin Out_1 outputs a low-level signal. The second inverter (as the load side) then receives the low-level signal from the output IO pin Out_1 via the input IO pin In_2 and performs a phase-locked grid connection operation. Alternatively, when the voltage angle of the first inverter (as the grid-side inverter) reaches 2π, the control output IO pin Out_1 outputs a high-level signal. The second inverter (as the load side) then receives the high-level signal from the output IO pin Out_1 via the input IO pin In_2 and performs a phase-locked grid connection operation.

[0063] Unlike traditional phase-locked loop (PLL) methods, in this embodiment, one inverter acts as the grid-side unit. The inverter acting as the load side obtains the voltage phase information of the grid-side inverter via I / O signals to determine whether the voltage angle of the grid-side inverter has reached a preset grid angle, such as π / 6 or 2π. After obtaining this voltage angle information, the load-side inverter adjusts its control angle according to the phase information to keep its voltage phase synchronized with that of the grid-side inverter, thus achieving PLL grid connection. Since the two inverters have the same control frequency and the same voltage angle update step size, after obtaining the voltage angle information of the grid-side inverter once, the load-side inverter can continuously track the voltage phase changes of the grid-side inverter, thereby maintaining phase synchronization. Compared to traditional PLL methods based on grid voltage sampling, the above method directly obtains the phase information of the grid-side inverter via I / O signals, which can improve PLL accuracy and is suitable for inverter aging test scenarios.

[0064] It should be noted that this embodiment does not specifically limit the hardware structure or topology of the energy storage aging test system. Any system structure that can realize the phase-locked synchronization function between two inverters can be applied to the method of this invention.

[0065] Step S200: Obtain the first instantaneous voltage value of the inverter acting as the grid end and the second instantaneous voltage value of the inverter acting as the load end.

[0066] Figure 4 It shows Figure 2 The flowchart shown illustrates the method for obtaining the first and second instantaneous voltage values ​​in step S200. Figure 4 As shown, step S200 may include steps S201 to S202.

[0067] Step S201: Determine the first instantaneous voltage value based on the effective value of the target voltage of the inverter acting as the grid end and the synchronization angle after phase-locked connection.

[0068] In off-grid operation mode, the inverter acting as the grid-side inverter outputs an AC voltage signal and sets a target effective voltage value according to control commands. The target effective voltage value can be set by the control unit and sent to each inverter. After phase-locked loop (PLL) grid connection is completed, the inverter acting as the load side obtains voltage angle information synchronized with the inverter acting as the grid-side inverter through a PLL process and uses this angle as the synchronization angle. In one embodiment, the load-side inverter calculates the instantaneous voltage value at the corresponding moment based on the synchronization angle and the target effective voltage value of the grid-side inverter, thereby determining the first instantaneous voltage value.

[0069] exist Figure 1In the illustrated embodiment, the inverter acting as the grid end sends the target voltage RMS value to the PC host computer via the RS485-1 interface. The PC host computer then sends this target voltage RMS value to the inverter acting as the load end via the RS485-3 interface. After obtaining the target voltage RMS value, the inverter acting as the load end calculates the first instantaneous voltage value at the corresponding moment by combining it with the synchronization angle after phase-locked grid connection. This first instantaneous voltage value is calculated in the following way:

[0070] ;

[0071] Among them, U 1i U represents the instantaneous value of the first voltage corresponding to the i-th sampling time. rms θ represents the effective value of the target voltage of the inverter acting as the grid terminal. i This indicates the synchronization angle obtained after phase-locked loop (PLL) grid connection.

[0072] Step S202: Sample and obtain the voltage of the inverter's grid connection port, which acts as the load, and obtain the second instantaneous voltage value.

[0073] The second instantaneous voltage value corresponds to the actual voltage sample value at the grid connection port of the inverter, which acts as the load. Since this voltage is the actual voltage signal after the inverter at the load end is connected to the analog grid, it can reflect the true voltage situation of the grid-connected node under the current operating state. By obtaining this actual sampled voltage as the second instantaneous voltage value, it can be compared with the first instantaneous voltage value calculated in step S201, and thus used for subsequent voltage error calculation.

[0074] Step S300: Based on the cumulative voltage error value of the first and second instantaneous voltage values ​​within a preset statistical period, adaptively adjust the parameters of the current loop at the grid connection port of the inverter that acts as the load end.

[0075] Figure 5 It shows Figure 2 The diagram shows a schematic flowchart of the method for adjusting the current loop parameters based on the cumulative voltage error value in step S300. Figure 5 As shown, step S300 may include steps S301 to S305.

[0076] Step S301: Divide the preset statistical period into multiple angle intervals and determine the number of voltage samplings for each angle interval.

[0077] The preset statistical period is a pre-defined time period, the length of which can be one half-cycle of the power frequency, such as the positive half-cycle of the power frequency, i.e., the voltage phase angle range is 0-π. It can also be set according to actual control requirements, and this embodiment of the invention does not impose a specific limitation on it. The purpose of setting the preset statistical period is to perform statistical analysis on the instantaneous values ​​of the first voltage and the second voltage within a certain time range, thereby reflecting the overall voltage deviation between the two over a longer period, rather than the instantaneous voltage characteristics at a single moment.

[0078] Dividing the preset statistical period into multiple angular intervals is to distinguish the differences in the instantaneous voltage value change characteristics at different phase positions, enabling the instantaneous voltage values ​​within each angular interval to be differentiated for statistical analysis. This avoids interference from local phase fluctuations in the overall judgment and improves the accuracy of voltage error analysis. In one embodiment, the preset statistical period from 0 to π can be divided into multiple angular intervals, for example, into six angular intervals: [0, π / 6), [π / 6, π / 3), [π / 3, π / 2), [π / 2, 2π / 3), [2π / 3, 5π / 6), and [5π / 6, π].

[0079] The number of voltage samplings within each angle interval can be determined based on the voltage sampling frequency of the control system and the phase change within a preset statistical period. Specifically, the inverter, acting as the load, periodically samples the grid-connected voltage according to a preset control frequency, acquires the corresponding instantaneous voltage value at each sampling moment, and assigns the instantaneous voltage value to the corresponding angle interval based on the voltage phase angle at that sampling moment.

[0080] In one embodiment, the sampling frequency of the main control unit of the energy storage inverter is f. ctrl If the power frequency is f, then the number of samples in one power frequency cycle is f. ctrl / f. Since the preset statistical period in this embodiment is the positive half-cycle of the power frequency, the number of samples within this statistical period is f. ctrl / 2f. After dividing the statistical period into multiple angle intervals, the number of voltage samples contained in each angle interval can be determined according to the phase range corresponding to each angle interval, thereby obtaining the voltage sampling data corresponding to each angle interval. When the preset statistical period is the positive half-cycle of the power frequency and is divided into six angle intervals, the number of voltage samples m corresponding to each angle interval can be expressed as f. ctrl / 12f.

[0081] Step S302: Calculate the average voltage value for each angle interval based on the first instantaneous voltage value and the second instantaneous voltage value within each angle interval.

[0082] Within each angular interval, the inverter, acting as the load, acquires voltage data corresponding to multiple sampling moments at a preset sampling frequency. At each sampling moment, a corresponding first and second instantaneous voltage value can be obtained simultaneously. The first instantaneous voltage value is a reference voltage instantaneous value calculated based on the target voltage RMS value and the synchronization angle, while the second instantaneous voltage value is the actual voltage instantaneous value sampled at the grid connection port. Therefore, several sets of corresponding first and second instantaneous voltage values ​​can be obtained within each angular interval. By statistically averaging the absolute values ​​of the first and second instantaneous voltage values ​​obtained from multiple samplings within a corresponding angular interval, the average voltage value within that angular interval can be obtained.

[0083] In an optional embodiment, the preset statistical period is divided into k angle intervals, and the number of samplings for each angle interval is determined to be m. The average voltage of each angle interval is calculated using the following formula:

[0084] Where j = 1, 2, ..., k;

[0085] in, Let U be the average voltage over the j-th angular interval. 2i U represents the instantaneous value of the second voltage at the i-th sampling time. 1i This represents the instantaneous value of the first voltage at the i-th sampling time.

[0086] It is worth noting that the ideal first instantaneous voltage value is obtained by calculating the target voltage RMS value and the synchronization angle, while the second instantaneous voltage value is the sampled value. This is used to solve for the voltage mean. Simultaneously considering the instantaneous values ​​of the first and second voltages helps to eliminate interference factors and improve accuracy.

[0087] Step S303: Determine the voltage weighting coefficient for each angle interval based on the sum of the average voltage values ​​of multiple angle intervals and the average voltage value of each angle interval.

[0088] To reflect the impact of voltage amplitude variations at different phase positions on the overall voltage error, the corresponding voltage weighting coefficient can be determined based on the average voltage value of each angle interval. Specifically, the sum of the average voltage values ​​across all angle intervals can be calculated first, and then the voltage weighting coefficient for each angle interval can be determined based on the proportion of the average voltage value of each angle interval to the total average voltage value. The voltage weighting coefficient for each angle interval can be calculated using the following formula:

[0089] Where n = 1, 2, ..., k;

[0090] in, This represents the average voltage value in the nth angular interval. This represents the average voltage value in the t-th angle interval. This represents the voltage weighting coefficient for the nth angular interval.

[0091] By determining the voltage weighting coefficients for each angle interval using the above method, the angle intervals with larger voltage amplitudes can occupy a higher weight in subsequent error calculations, thereby more accurately reflecting the influence of different phase positions on the overall voltage error.

[0092] Step S304: The voltage weighting coefficients of each angle interval and the voltage deviation between the first and second instantaneous voltage values ​​of each angle interval are weighted and summed to obtain the cumulative voltage error value.

[0093] Specifically, when the phase angle corresponding to the i-th sampling time falls into the n-th angle interval, the voltage weighting coefficients corresponding to those n angle intervals can be used. The voltage deviation is weighted to obtain the weighted voltage deviation. After obtaining the weighted voltage deviation at each sampling time, the weighted voltage deviations corresponding to all sampling times within a preset statistical period can be accumulated to obtain the cumulative voltage error value. The cumulative voltage error value ΔU sum The formula can be expressed as:

[0094] .

[0095] Where k is the total number of angle intervals obtained by dividing the data into preset statistical periods, and m is the number of samples for each angle interval. is the voltage weighting coefficient for the k-th angle interval.

[0096] Step S305: Based on the relationship between the cumulative voltage error value and the preset error threshold, the parameters of the current loop at the grid connection port are adaptively adjusted.

[0097] After obtaining the cumulative voltage error value within a preset statistical period, this cumulative voltage error value can be compared with a preset error threshold to determine whether the parameters of the current loop need to be adjusted. The preset error threshold can be used to characterize the allowable voltage deviation range. When the cumulative voltage error value exceeds this error threshold, it indicates that the current current loop parameters may not meet the requirements for stable system operation, and the current loop parameters need to be adjusted. The preset statistical period can be one power frequency cycle. In an optional embodiment, the preset error threshold is a pre-set error value, and the error threshold is the product of the cumulative value of the first instantaneous voltage value within the preset statistical period and a first proportional coefficient. The preset error threshold S satisfies the following formula:

[0098] S=γ× ,

[0099] Where k is the total number of angle intervals obtained by dividing the system into preset statistical periods, m is the number of voltage samplings in each interval, and γ is a first proportionality coefficient used to characterize the allowable voltage error ratio. This proportionality coefficient can be set according to the system control requirements. For example, γ can be 0.03, but this embodiment of the invention does not specifically limit it.

[0100] Figure 6 It shows Figure 5 The diagram shows a schematic flowchart of the method for adjusting the current loop parameters in step S305. Figure 5 As shown, step S305 may include steps S3051 to S3052.

[0101] It should be noted that the initial parameters are for a real-world grid connection scenario. The real-world grid voltage generally does not change with the grid current. The initial parameters are the default control parameters used by the current loop under real-world grid operation, characterizing the stable control state of the current loop under standard operating conditions. However, in the aging test of this application, we form a counter-current system using inverters, with one inverter acting as the grid. This is equivalent to a weak grid. The high impedance characteristics of a weak grid alter the equivalent control model of the current loop, reducing system stability and causing current oscillations, resulting in a deviation between the actual power and the target power. Adjusting the current loop parameters using our cumulative voltage error value can improve system stability, suppress current oscillations, and improve response accuracy. The initial parameters include initial proportional parameters and initial integral parameters.

[0102] Step S3051: When the cumulative voltage error value is greater than the preset error threshold, determine the loop parameter adjustment value of the current loop based on the current loop parameter value at the current moment and the adjustment step size determined based on the initial parameters.

[0103] Specifically, the adjustment step size includes a first adjustment step size for adjusting the proportional parameter of the current loop and a second adjustment step size for adjusting the integral parameter of the current loop. The adjustment value of the proportional parameter of the current loop is the proportional parameter at the current moment minus the first adjustment step size, and the adjustment value of the integral parameter of the current loop is the integral parameter at the current moment minus the second adjustment step size.

[0104] In one embodiment, the adjustment step size determined based on the initial parameters may include steps A through C.

[0105] Step A: Obtain the initial proportional parameter K of the current loop. p (0) and initial integration parameter K i (0).

[0106] Step B: Based on the initial scaling parameter K p(0) and the product of the second proportional coefficient α, determine the first adjustment step size ΔK for adjusting the proportional parameter of the current loop. p .

[0107] In one embodiment, the first adjustment step size is calculated using the following formula:

[0108] ;

[0109] Where 0.01 ≤ α ≤ 0.03. For example, α can take the values ​​0.01, 0.02, or 0.03.

[0110] Step C: Based on the initial integration parameter K i The product of (0) and the third proportional coefficient β determines the second adjustment step size ΔK for the integral parameter used to adjust the current loop. i .

[0111] In one embodiment, the second adjustment step size is calculated using the following formula:

[0112] ;

[0113] Where 0.005 ≤ β ≤ 0.015. For example, β can take the values ​​0.005, 0.01, or 0.015.

[0114] It should be noted that the second proportional coefficient α and the third proportional coefficient β are preset constant values, and can be flexibly set according to the system stability requirements and aging test scenarios. They are used to determine the change range of the proportional and integral parameter adjustment step size relative to the initial parameters, thereby ensuring that the parameter adjustment range matches the degree of error deviation. This avoids slow convergence due to excessive adjustment and prevents system oscillation caused by excessive adjustment, ensuring that the current loop parameters are smoothly adjusted within the stable range.

[0115] In one specific embodiment, α is set to 0.02 and β is set to 0.01, then the first adjustment step size ΔK p Second adjustment step size ΔK i The following formula is used to calculate:

[0116] , .

[0117] Step S3052: When the cumulative voltage error value is less than or equal to the preset error threshold, determine the adjustment value of the current loop parameters based on the relationship between the current loop parameter value and the initial parameter.

[0118] In one embodiment, step S3052 includes the following steps: when the loop parameter value at the current moment is less than the initial parameter, the sum of the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value; when the loop parameter value at the current moment is greater than the initial parameter, the difference between the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value; when the loop parameter value at the current moment is equal to the initial parameter, the loop parameter adjustment value is determined as the initial parameter.

[0119] Using the above method, when the cumulative voltage error value is less than or equal to the preset error threshold, the current loop parameters can be gradually reverted to the initial parameters, thereby restoring the current loop to a control state close to standard operating conditions. In this embodiment, the adjustment step size is consistent with the determination method in step S3051, and will not be repeated here.

[0120] In one specific embodiment, when the cumulative voltage error value ΔU sum Less than or equal to the preset error threshold S, i.e. At that time, the adjustment value of the proportional parameter of the current loop is determined as follows:

[0121] When the current scaling parameter value K p Less than the initial scaling parameter K p (0), i.e., K p <K p (0) The adjustment value of the proportional parameter of the current loop is the proportional parameter value K at the current moment. p With the first adjustment step size ΔK p sum;

[0122] When the current scaling parameter value K p Greater than the initial scaling parameter K p (0), i.e., K p >K p (0) The adjustment value of the proportional parameter of the current loop is the proportional parameter value K at the current moment. p With the first adjustment step size ΔK p difference;

[0123] When the current scaling parameter value K p Equal to the initial scaling parameter K p (0), i.e., K p =K p When (0), the adjustment value of the proportional parameter of the current loop is the initial proportional parameter K. p (0).

[0124] Similarly, At that time, the adjustment values ​​of the integral parameters of the current loop are determined as follows:

[0125] When the current integral parameter value Ki Less than the initial integration parameter K i (0), i.e., K i <K i When (0), the adjustment value of the integral parameter of the current loop is the integral parameter value K at the current moment. i Increase the second adjustment step size ΔK i sum;

[0126] When the current integral parameter value K i Greater than the initial integration parameter K i (0), i.e., K i >K i When (0), the adjustment value of the integral parameter of the current loop is the integral parameter value K at the current moment. i With the second adjustment step size ΔK i difference;

[0127] When the current integral parameter value K i Equal to the initial integration parameter K i (0), i.e., K i =K i When (0), the adjustment value of the integral parameter of the current loop is the initial integral parameter K. i (0).

[0128] It should be noted that the adjustment of the loop parameters back towards the initial parameters is essentially a parameter regression mechanism. When the cumulative voltage error value is less than or equal to the preset error threshold, it indicates that the current control state is within an acceptable range. At this point, the parameter deviation is no longer amplified; instead, the parameters are gradually brought back to converge towards the default control parameters under the actual power grid scenario, thereby avoiding the control characteristic drift problem caused by long-term deviation from the initial set value. Through the above settings, the current loop parameters can be suppressed and adjusted when the error is too large, and can gradually return to the optimized parameter range under standard operating conditions after the error recovers to a reasonable range. This ensures system stability while maintaining the consistency and recoverability of control performance, improving the controllability and reliability of the entire aging test process.

[0129] According to the present invention, by controlling the inverter acting as the grid end and the inverter acting as the load end to be connected in phase-locked loop, a stable mutual support relationship is formed between the two inverters during the aging test. This allows for the synchronous acquisition of the instantaneous voltage values ​​of both inverters and the statistical calculation of the cumulative voltage error value. Based on the cumulative voltage error value, the current loop parameters at the grid connection port of the load-end inverter are adaptively adjusted. In other words, the circuit loop parameters are dynamically adjusted according to the actual situation of each inverter during the aging test, which helps ensure the stability and accuracy of the aging test process. Furthermore, by dividing the preset statistical period into multiple angle intervals and introducing voltage weighting coefficients for partitioned weighted statistics, errors at different phase positions are differentiated and evaluated, thereby improving the calculation accuracy of the cumulative voltage error value. Simultaneously, by setting an error threshold related to the cumulative voltage of the preset period, the error judgment can adapt to changes, thus avoiding the risk of misjudgment caused by a fixed threshold. Furthermore, by determining the adjustment step size based on the initial parameters and reducing the adjustment when the error exceeds the threshold, and then reverting back towards the initial parameters when the error falls back, the current loop parameters are always dynamically converged within the stable range, thereby suppressing current oscillations and waveform distortion, and improving the reliability and consistency of the entire aging test process.

[0130] In one embodiment, a computer storage medium is also provided, which can store program instructions that, when executed by a processor, can implement the loop parameter adaptive adjustment method described above.

[0131] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in the details; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A loop parameter adaptive adjustment method, applied to an energy storage aging test system, the energy storage aging test system comprising at least two inverters, characterized in that, The method includes: The inverter acting as the grid end and the other inverter acting as the load end are controlled to perform phase-locked grid connection; Obtain the first instantaneous voltage value of the inverter that acts as the grid end and the second instantaneous voltage value of the inverter that acts as the load end; Based on the cumulative voltage error between the first instantaneous voltage value and the second instantaneous voltage value within a preset statistical period, the parameters of the current loop at the grid connection port of the inverter, which acts as the load end, are adaptively adjusted. The adjustment of the parameters of the current loop at the grid-connected port of the inverter, which acts as the load end, based on the cumulative voltage error value of the first and second instantaneous voltage values ​​within a preset statistical period includes: dividing the preset statistical period into multiple angle intervals and determining the number of voltage samplings for each angle interval; calculating the average voltage value for each angle interval based on the first and second instantaneous voltage values ​​within each angle interval; determining the voltage weighting coefficient for each angle interval based on the sum of the average voltage values ​​of multiple angle intervals and the average voltage value of each angle interval; weighting and summing the voltage weighting coefficients of each angle interval and the voltage deviation between the first and second instantaneous voltage values ​​of each angle interval to obtain the cumulative voltage error value; and adaptively adjusting the parameters of the current loop at the grid-connected port based on the relationship between the cumulative voltage error value and a preset error threshold.

2. The adaptive adjustment method for loop parameters according to claim 1, characterized in that, The preset error threshold is the product of the cumulative value of the first instantaneous voltage value within the preset statistical period and the first proportional coefficient.

3. The adaptive adjustment method for loop parameters according to claim 1, characterized in that, Based on the relationship between the accumulated voltage error value and the preset error threshold, the parameters of the current loop at the grid connection port are adaptively adjusted, including: When the cumulative voltage error value is greater than the preset error threshold, the loop parameter adjustment value of the current loop is determined based on the current loop parameter value at the current moment and the adjustment step size determined based on the initial parameters. When the cumulative voltage error value is less than or equal to the preset error threshold, the loop parameter adjustment value of the current loop is determined according to the relationship between the current loop parameter value at the current moment and the initial parameter; The initial parameters include the initial proportional parameters and initial integral parameters of the current loop.

4. The loop parameter adaptive adjustment method according to claim 3, characterized in that, The adjustment step size determined based on the initial parameters includes: Obtain the initial proportional parameters and initial integral parameters of the current loop; Based on the product of the initial proportional parameter and the second proportional coefficient, a first adjustment step size for adjusting the proportional parameter of the current loop is determined; Based on the product of the initial integral parameter and the third proportional coefficient, a second adjustment step size for adjusting the integral parameter of the current loop is determined.

5. The loop parameter adaptive adjustment method according to claim 3, characterized in that, Based on the relationship between the current loop parameter values ​​and the initial parameters, the adjustment values ​​of the current loop parameters are determined, including: When the loop parameter value at the current moment is less than the initial parameter, the sum of the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value; When the loop parameter value at the current moment is greater than the initial parameter, the difference between the loop parameter value at the current moment and the adjustment step size is determined as the loop parameter adjustment value; When the loop parameter at the current moment is equal to the initial parameter, the adjusted value of the loop parameter is determined to be the initial parameter.

6. The method for adaptive adjustment of loop parameters according to any one of claims 1 to 5, characterized in that, Acquiring the first instantaneous voltage value of the inverter acting as the grid terminal and the second instantaneous voltage value of the inverter's grid connection port acting as the load terminal includes: The first instantaneous voltage value is determined based on the effective value of the target voltage of the inverter acting as the grid end and the synchronization angle after phase-locked connection. The voltage of the inverter's grid connection, which acts as the load, is sampled to obtain the instantaneous value of the second voltage.

7. The loop parameter adaptive adjustment method according to any one of claims 1 to 5, characterized in that, Controlling one inverter acting as the grid end and another inverter acting as the load end to perform phase-locked grid connection includes: At a preset grid angle, the inverter acting as the grid end sends a preset level signal to the inverter acting as the load end via its IO pin. The inverter acting as the grid end and the inverter acting as the load end are controlled to perform phase-locked grid connection.

8. An energy storage aging test system, characterized in that, include: At least two inverters, each of which includes an off-grid port, a grid-connected port, and I / O pins; At least one switch, each of the switches being used to connect the off-grid port of one inverter to the grid-connected port of another inverter, wherein the inverter connected to the off-grid port by the switch acts as the grid end and the inverter connected to the grid-connected port by the switch acts as the load end; A control unit is communicatively connected to the inverter and the switch. The control unit is used to control the switching on and off, and to perform the loop parameter adaptive adjustment method as described in any one of claims 1 to 7 when aging tests are performed on the inverter.

9. A computer storage medium, characterized in that, The computer storage medium can store program instructions, which, when executed by a processor, can implement the loop parameter adaptive adjustment method as described in any one of claims 1 to 7.

Images