Phase-locked loop correction method and system, electronic equipment and computer readable storage medium

Abstract

The invention discloses a phase-locked loop correction method and system, electronic equipment and a computer readable storage medium, and relates to the field of grid-connected converters, and the phase-locked loop correction method comprises the steps: obtaining a grid-connected reactive current and an initial phase-locked loop angle of a current calculation period; determining a phase compensation value corresponding to the grid-connected reactive current; the symbol of the phase compensation value changes along with the symbol of the grid-connected reactive current in the current calculation period; and superposing the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle, and performing coordinate transformation operation by taking the target phase-locked loop angle as a directional angle of the current converter system. According to the method, the orientation angle of the system can be more efficiently corrected, the coupling degree of active and reactive components is reduced, the control precision and the grid-connected control power factor are improved, and the reactive current component in the network access current is reduced, so that the heating loss of the cable is reduced.

Description

Technical Field

[0001] The present invention relates to the field of grid-connected converters, and in particular to a phase-locked loop correction method, system, electronic equipment and computer-readable storage medium. Background Art

[0002] In the three-phase grid-connected converter system, the phase-locked loop is an indispensable component. It samples the grid voltage at the grid connection point and uses the three-phase software phase-locked loop technology to obtain the grid voltage vector angle. The grid voltage vector angle is used as a directional reference angle to decompose the grid current into active current components and reactive current components, and then control them separately. However, the grid voltage vector angle obtained using the three-phase software phase-locked loop often deviates from the actual grid voltage phase, resulting in inaccurate angles used for coordinate transformation.

[0003] At present, in order to improve the performance of the phase-locked loop, the common practice is to perform fixed compensation on the grid voltage vector angle output by the phase-locked loop, that is, to compensate for the phase offset value of a calculation cycle. This method is based on the assumption that the delay of each calculation cycle is constant, but in fact, the phase deviation of the phase-locked loop output angle may vary due to hardware filtering, reactor voltage drop, signal communication delay, software filter and other factors in addition to being affected by the calculation cycle. Therefore, this fixed compensation value is not always accurate, which in turn affects the control accuracy of the system.

[0004] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Summary of the invention

[0005] The purpose of the present invention is to provide a phase-locked loop correction method, system, electronic device and computer-readable storage medium, which can more efficiently correct the system orientation angle, reduce the degree of coupling between active and reactive components, improve control accuracy and grid-connected control power factor, reduce the reactive current component in the grid-connected current, and thus reduce cable heating losses.

[0006] In a first aspect, the present invention provides a phase-locked loop calibration method, comprising:

[0007] Obtain the grid-connected reactive current and initial phase-locked loop angle of the current calculation cycle;

[0008] Determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle;

[0009] The phase compensation value and the initial phase-locked loop angle are superimposed to obtain a target phase-locked loop angle, and the target phase-locked loop angle is used as the orientation angle of the current converter system to perform a coordinate transformation operation.

[0010] Optionally, the process of determining a phase compensation value corresponding to the grid-connected reactive current includes:

[0011] Determine the current iteration period in which the current calculation period is located, where the duration of the iteration period is greater than the duration of the calculation period;

[0012] Obtaining a correction coefficient for the current iteration cycle; the correction coefficient is determined according to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0013] The phase compensation value is calculated using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency.

[0014] Optionally, the process of obtaining the correction coefficient of the current iteration cycle includes:

[0015] If the current iteration cycle is the first iteration cycle, determining the correction coefficient of the current iteration cycle to be an initial coefficient corresponding to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0016] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is positive, determine that the correction coefficient of the current iteration cycle is the first coefficient, and the first coefficient is greater than the correction coefficient of the i-1-th iteration cycle, i=2, 3, ..., n, n is the total number of iterations;

[0017] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is negative, the correction coefficient of the current iteration cycle is determined to be the second coefficient, and the second coefficient is smaller than the correction coefficient of the i-1-th iteration cycle.

[0018] Optionally, the phase-locked loop correction method further includes:

[0019] If the current iteration cycle is the i-th iteration cycle, determining whether the first grid-connected reactive current obtained in the i-th iteration cycle is within a preset accuracy range;

[0020] If so, determining the correction coefficient of the i-th iteration cycle as the optimal coefficient;

[0021] The process of obtaining the correction coefficient of the current iteration cycle includes:

[0022] If the current iteration cycle is the jth iteration cycle, the correction coefficient of the current iteration cycle is determined to be the optimal coefficient, i<j≤n.

[0023] Optionally, after calculating the phase compensation value using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency, the phase-locked loop correction method further includes:

[0024] Filtering the phase compensation value through a first low-pass filter to obtain a target compensation value;

[0025] The process of superimposing the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle includes:

[0026] The target compensation value and the initial phase-locked loop angle are superimposed to obtain a target phase-locked loop angle.

[0027] Optionally, the process of determining a phase compensation value corresponding to the grid-connected reactive current includes:

[0028] Filtering the grid-connected reactive current through a second low-pass filter to obtain a target reactive current;

[0029] A phase compensation value corresponding to the target reactive current is determined.

[0030] Optionally, the process of obtaining the grid-connected reactive current in the current calculation period includes:

[0031] Determining a type of output filter of the current converter system;

[0032] Obtaining the converter machine-side current of the current calculation cycle;

[0033] Calculating the grid-connected current based on the type and the converter machine-side current;

[0034] The grid-connected reactive current is obtained by performing the coordinate transformation operation on the grid-connected current.

[0035] In a second aspect, the present invention further provides a phase-locked loop correction system, comprising:

[0036] An acquisition module is used to obtain the grid-connected reactive current and the initial phase-locked loop angle of the current calculation cycle;

[0037] A determination module, used to determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle;

[0038] The compensation module is used to superimpose the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle, and use the target phase-locked loop angle as the orientation angle of the current converter system to perform a coordinate transformation operation.

[0039] In a third aspect, the present invention further provides an electronic device, comprising:

[0040] Memory for storing computer programs;

[0041] A processor is used to implement the steps of the phase-locked loop correction method as described in any one of the above when executing the computer program.

[0042] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the phase-locked loop correction method as described in any one of the above are implemented.

[0043] The present invention provides a phase-locked loop correction method, which first obtains the grid-connected reactive current and the initial phase-locked loop angle of the current calculation cycle, and determines the phase compensation value of the phase-locked loop angle based on the sign of the grid-connected reactive current. The phase compensation value changes dynamically with the sign of the grid-connected reactive current, and can correct the system directional angle more efficiently, reduce the degree of coupling between active and reactive components, improve control accuracy, and improve the grid-connected control power factor, reduce the reactive current component in the grid-connected current, thereby reducing cable heating loss.

[0044] The present invention also provides a phase-locked loop correction system, an electronic device and a computer-readable storage medium, which have the same beneficial effects as the above-mentioned phase-locked loop correction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A flow chart of the steps of a phase-locked loop calibration method provided by the present invention;

[0047] Figure 2 A schematic diagram of grid-connected reactive current symbol recognition provided by the present invention;

[0048] Figure 3 A phase-locked loop calibration flow chart provided by the present invention;

[0049] Figure 4a , Figure 4b , Figure 4c , Figure 4d A simulation waveform diagram provided by the present invention;

[0050] Figure 5 A schematic diagram of the structure of a phase-locked loop correction system provided by the present invention;

[0051] Figure 6 A schematic diagram of the structure of an electronic device provided by the present invention;

[0052] Figure 7 This is a schematic diagram of the structure of a computer-readable storage medium provided by the present invention. DETAILED DESCRIPTION

[0053] The core of the present invention is to provide a phase-locked loop correction method, system, electronic device and computer-readable storage medium, which can more efficiently correct the system orientation angle, reduce the degree of coupling between active and reactive components, improve control accuracy and grid-connected control power factor, reduce the reactive current component in the grid-connected current, and thus reduce cable heating losses.

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] In a first aspect, the present invention provides a phase-locked loop calibration method, comprising:

[0056] S101: Obtaining the grid-connected reactive current and initial phase-locked loop angle of the current calculation cycle;

[0057] In this embodiment, the grid-connected reactive current is obtained according to a preset calculation cycle to compensate the initial phase-locked loop angle, thereby improving the real-time performance of the angle compensation and enabling the current converter system to quickly respond to dynamic changes in the grid state. Moreover, continuous correction can gradually reduce the cumulative error, and it is not easy to cause over-compensation during the correction process. The grid-connected reactive current in this embodiment is obtained by decomposing the grid-side current of the grid-connected converter in the current calculation cycle after coordinate transformation, and the initial phase-locked loop angle is the phase-locked loop angle that has not been corrected and is calculated based on the grid voltage at the grid connection point in the current calculation cycle and the three-phase software phase-locked loop technology.

[0058] S102: Determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle;

[0059] S103: superimposing the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle, and performing a coordinate transformation operation using the target phase-locked loop angle as the orientation angle of the current converter system.

[0060] In this embodiment, the sign of the grid-connected reactive current is identified, and the phase lead-lag relationship between the initial phase-locked loop angle and the actual grid voltage angle can be obtained based on the sign of the grid-connected reactive current. The current direction is positive from the grid input converter. Under the control target of unit power factor, the grid voltage and the grid current should be consistent in phase, and the ideal value of the reactive current component is 0. If there is a phase difference between the initial phase-locked loop angle and the grid voltage angle, the decomposed reactive current component is not 0.

[0061] like Figure 2 As shown in the figure, if the sign of the grid-connected reactive current is positive, that is, the grid-connected reactive current is greater than 0, then the initial phase-locked loop angle lags behind the actual grid voltage angle; if the sign of the grid-connected reactive current is negative, that is, the grid-connected reactive current is less than 0, then the initial phase-locked loop angle leads the actual grid voltage angle. Figure 2 In the equation, q represents the q axis, d represents the d axis, and t=0 is the starting time. Figure 2 Only the decomposition on the positive half axis of dq is drawn, that is, the grid-connected reactive current is greater than 0. If the decomposition is on the negative half axis of dq, the grid-connected reactive current is less than 0. Figure 2 middle, I grid Indicates the grid-connected current, U grid Indicates the grid voltage, represents the phase difference, Indicates the grid-connected active current, Indicates the grid-connected reactive current, Indicates the grid voltage angle, Indicates the initial phase-locked loop angle.

[0062] In this example, by adjusting the initial phase-locked loop angle Add a phase compensation value Then as the new system orientation angle .

[0063] Defined as , .

[0064] When the sign of the grid-connected reactive current is positive, When the initial phase-locked loop angle lags behind the actual grid voltage angle, the sign of the phase compensation value is positive. When the sign of the grid-connected reactive current is negative, , the initial phase-locked loop angle is ahead of the actual grid voltage angle, and the sign of the phase compensation value is negative. The sign of the phase compensation value changes dynamically with the sign of the grid-connected reactive current, which can perform phase compensation more accurately, improve the tracking performance of the phase-locked loop and the stability of the system. Dynamic adjustment of the sign of the compensation amount helps to reduce the compensation error caused by the fixed compensation strategy and improve the overall control accuracy of the system. In addition, by dynamically adjusting the phase compensation, the flow of reactive power can be effectively controlled and the power factor of the grid can be improved. It can be understood that if the phase compensation value is selected reasonably, it can just offset the original phase shift error. , then the orientation angle of the current converter system is will be equal to the actual grid voltage angle .

[0065] It can be seen that in this embodiment, the grid-connected reactive current and the initial phase-locked loop angle of the current calculation cycle are first obtained, and the phase compensation value of the phase-locked loop angle is determined based on the sign of the grid-connected reactive current. The phase compensation value changes dynamically with the sign of the grid-connected reactive current, which can more efficiently correct the system orientation angle, reduce the degree of coupling between active and reactive components, improve control accuracy, and improve the grid-connected control power factor, reduce the reactive current component in the grid-connected current, and thus reduce cable heating losses.

[0066] Based on the above embodiments:

[0067] In an exemplary embodiment, the process of determining a phase compensation value corresponding to a grid-connected reactive current includes:

[0068] Determine the current iteration cycle of the current calculation cycle, and the time length of the iteration cycle is greater than the time length of the calculation cycle;

[0069] Obtaining a correction coefficient for the current iteration cycle; the correction coefficient is determined according to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0070] The phase compensation value is calculated using the correction coefficient, the calculated cycle frequency and the grid cycle angular frequency.

[0071] In this embodiment, the non-constant coefficients used to calculate the phase compensation value are iterated regularly, which can gradually reduce the steady-state error in the compensation process, so that the system can maintain a high phase tracking accuracy after long-term operation, and can also avoid over-compensation or under-compensation problems caused by fixed compensation strategies, ensuring the best compensation effect.

[0072] In this embodiment, the time length of the iteration cycle of the phase compensation value is greater than the time length of the calculation cycle corresponding to the phase-locked loop correction. An iteration cycle may include multiple calculation cycles. In the same iteration cycle, the phase compensation value is calculated according to the same correction coefficient. The slower iteration cycle can make the adjustment of the phase compensation value smoother, avoiding frequent adjustment of the phase compensation value and causing unnecessary disturbances to the system. As an optional embodiment, the time length of the iteration cycle should not be less than the time length T of 1000 calculation cycles. cal .

[0073] Specifically, when determining the correction coefficient of the current iteration cycle, the present embodiment needs to determine the correction coefficient of the current iteration cycle according to the sign of the first grid-connected reactive current obtained in the iteration cycle, and calculate the phase compensation value using the correction coefficient, the calculation cycle frequency, and the grid cycle angular frequency. For example, assuming that the sign of the first grid-connected reactive current obtained in the current iteration cycle is positive, the correction coefficient K of the current iteration cycle is coef =K11, the sign of the first grid-connected reactive current obtained in the current iteration cycle is negative, then the correction coefficient K coef =K12.

[0074] In this embodiment, the phase compensation value is calculated specifically according to the first relational expression, which is: ,in, is the grid cycle angular frequency, f cal To calculate the periodic frequency.

[0075] In an exemplary embodiment, the process of obtaining the correction coefficient of the current iteration cycle includes:

[0076] If the current iteration cycle is the first iteration cycle, determining the correction coefficient of the current iteration cycle to be an initial coefficient corresponding to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0077] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is positive, the correction coefficient of the current iteration cycle is determined to be the first coefficient, and the first coefficient is greater than the correction coefficient of the i-1-th iteration cycle, i=2, 3, ..., n, n is the total number of iterations;

[0078] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is negative, the correction coefficient of the current iteration cycle is determined to be the second coefficient, and the second coefficient is smaller than the correction coefficient of the i-1-th iteration cycle.

[0079] In this embodiment, if the current iteration cycle is the first iteration cycle, the initial coefficient can be selected according to the relevant parameters of the current converter system, and the initial coefficient is used as the correction coefficient of the first iteration cycle. The initial coefficient corresponds to the sign of the first grid-connected reactive current obtained in the first iteration cycle. Assuming that the sign of the first grid-connected reactive current obtained in the first iteration cycle is positive, the correction coefficient K coef =K11, assuming that the sign of the first grid-connected reactive current obtained in the first iteration cycle is negative, then the correction coefficient K coef =K12, as an optional embodiment, K11=-K12. In this embodiment, the initial value of the phase compensation value can be set to 0.

[0080] From the beginning of the second iteration cycle to the subsequent iteration cycles, the correction coefficient needs to be iteratively adjusted. Specifically, the correction coefficient can be selected according to the sign of the first grid-connected reactive current obtained in the i-th iteration cycle. The purpose to be achieved is to make the grid-connected reactive current infinitely close to 0. Assuming that the sign of the first grid-connected reactive current obtained in the i-th iteration cycle is positive, it indicates that the phase of the grid voltage lags behind the phase of the converter output current. In order to synchronize the converter with the grid, the phase compensation value needs to be increased to correct this phase difference. Then, it is necessary to continue to increase the correction coefficient. Then, a first coefficient that is larger than the correction coefficient of the i-1th iteration cycle is selected as the correction coefficient of the i-th iteration cycle to increase the phase compensation value. Assume that the sign of the first grid-connected reactive current obtained in the i-th iteration cycle is negative, indicating that the phase of the grid voltage leads the phase of the converter output current. In order to synchronize the converter with the grid, the phase compensation value needs to be reduced to correct this phase difference. Then, it is necessary to continue to reduce the correction coefficient. A second coefficient that is smaller than the correction coefficient of the i-1th iteration cycle is selected as the correction coefficient of the i-th iteration cycle to reduce the phase compensation value.

[0081] When determining the correction coefficient of the i-th iteration cycle, a binary method or an incremental accumulation method may be used but is not limited to, and these two methods are respectively described below.

[0082] The binary design of the phase correction compensation value has the advantages of high efficiency, simplicity and versatility. The initial value of the phase correction compensation is set to 0, and the grid-connected reactive current of the first iteration cycle (z=1) is obtained. ,like , take the correction factor , obtain the grid-connected reactive current in the second iteration cycle (z=2) , if its , take the correction factor , , obtain the grid-connected reactive current in the third iteration cycle (z=3) ,like , take the correction factor , , and so on, according to the dichotomy idea, the iterative correction coefficient is continuously optimized .

[0083] The incremental accumulation method is used to design the phase compensation value, and the absolute value of the fixed compensation increment is used. The sign of the compensation increment M is determined by the grid-connected reactive current Sign determination, correction factor is the cumulative value of all increments . Get the grid-connected reactive current in the first iteration cycle (z=1) ,like , take the correction factor ; Get the grid-connected reactive current in the second iteration cycle (z=2) , if its , take the correction factor ; Determine the grid-connected reactive current at the mth iteration cycle (z=m) , if its , take the correction factor , and so on, continuously optimize the iterative correction coefficient .

[0084] In an exemplary embodiment, the phase-locked loop calibration method further includes:

[0085] If the current iteration cycle is the i-th iteration cycle, determine whether the first grid-connected reactive current obtained in the i-th iteration cycle is within a preset accuracy range;

[0086] If so, the correction coefficient of the i-th iteration cycle is determined as the optimal coefficient;

[0087] The process of obtaining the correction coefficient of the current iteration cycle includes:

[0088] If the current iteration cycle is the jth iteration cycle, it is determined that the correction coefficient of the current iteration cycle is the optimal coefficient, i<j≤n.

[0089] In this embodiment, the preset accuracy range is determined according to the relevant parameters of the current converter system. If the first grid-connected reactive current obtained in the i-th iteration period is within the preset accuracy range, that is, , thereafter, the correction coefficient will no longer be iterated, and the correction coefficient of the i-th iteration cycle will be directly used as the optimal coefficient to calculate the subsequent phase compensation value, thereby reducing unnecessary adjustments and improving the long-term stability of the system. When the system is already within the preset accuracy range, the fixed correction coefficient can reduce the calculation delay and improve the response speed of the system. If the first grid-connected reactive current obtained in the i-th iteration cycle is not within the preset accuracy range, that is, the optimal coefficient is not obtained, the iterative calculation of the correction coefficient will continue in the subsequent iteration cycle, and the step of judging whether the first grid-connected reactive current obtained in the current iteration cycle is within the preset accuracy range will be repeated until the maximum number of iterations is reached or the optimal coefficient is obtained.

[0090] In an exemplary embodiment, after calculating the phase compensation value using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency, the phase-locked loop correction method further includes:

[0091] Filtering the phase compensation value through a first low-pass filter to obtain a target compensation value;

[0092] The process of superimposing the phase compensation value and the initial phase-locked loop angle to obtain the target phase-locked loop angle includes:

[0093] The target compensation value and the initial phase-locked loop angle are superimposed to obtain the target phase-locked loop angle.

[0094] In this embodiment, the phase compensation value needs to be filtered by a first-order low-pass filter and then superimposed on the initial phase-locked loop angle to avoid the impact of sudden phase changes on the current converter system.

[0095] In an exemplary embodiment, the process of determining a phase compensation value corresponding to a grid-connected reactive current includes:

[0096] The grid-connected reactive current is filtered by a second low-pass filter to obtain a target reactive current;

[0097] A phase compensation value corresponding to a target reactive current is determined.

[0098] In this embodiment, the grid-connected reactive current After a low-pass filter, a smooth grid-connected reactive current is obtained. , and then perform symbol judgment processing to filter out high-frequency signal interference and improve the accuracy of judgment.

[0099] In an exemplary embodiment, the process of obtaining the grid-connected reactive current of the current calculation cycle includes:

[0100] Determine the type of output filter of the current converter system;

[0101] Obtain the current of the converter machine side in the current calculation cycle;

[0102] Calculate the grid current based on the type and the converter machine-side current;

[0103] The grid-connected reactive current is obtained by performing coordinate transformation on the grid-connected current.

[0104] In this embodiment, considering that the current sampling point is at the output end of the converter, that is, the sampled current is the machine-side current, and the grid-connected current refers to the grid-side current, according to the difference in the type of output filter in the converter system, the machine-side current and the grid-side current are also different. When the filter type is a traditional single-inductor L filter, the machine-side current is equal to the grid-side current, and the sampled machine-side current is the grid-connected current; when the filter is an LCL filter, the machine-side current is not equal to the grid-side current, and the sampled machine-side current needs to be added with the filter capacitor current to obtain the grid-side grid-connected current. Under the LCL filter topology, the grid voltage sampling point is generally set at the filter capacitor C, so the filter capacitor current can be obtained by calculation, thereby improving the accuracy and reliability of the grid-connected reactive current obtained based on the decomposition of the grid-connected current.

[0105] In summary, refer to Figure 3 As shown, Figure 3 A phase-locked loop correction flow chart provided by the present invention is provided. By judging the sign of the current grid-connected reactive current, the phase lead or lag relationship between the phase-locked loop angle phase and the grid voltage angle is analyzed, and the total impact of all factors (such as hardware filtering, reactor voltage drop, signal communication delay, software filter, etc.) is evaluated. The phase-locked loop angle phase compensation value is designed according to the reactive current sign. The scheme is simple to implement. By calibrating the phase-locked loop angle phase, the system directional angle can be corrected, the coupling degree of active and reactive components can be reduced, the control accuracy can be improved, and the power factor can be improved. It is not only applicable to systems with single inductance L as the filter, but also to systems with LCL filters, and there is no need to install additional current sensors to sample the grid-side current under the LCL topology. The whole set is a software solution, which does not increase the hardware and structural costs. The phase compensation value scheme can be designed by dichotomy and incremental accumulation. The code is simple to implement and does not occupy too many computing resources. Under different load currents, the transformer or reactor voltage drop between the grid-connected converter and the grid is inconsistent, and the impact on the phase shift of the phase-locked loop is different. The solution of the present invention can be applied to different load conditions and can correct the phase offset online. The phase compensation value needs to pass through a first-order low-pass filter and then be superimposed on the phase-locked loop angle to avoid the impact of sudden phase changes on the system. In actual software processing, in order to filter out high-frequency signal interference, the grid-connected reactive current After a low-pass filter, a smooth reactive current is obtained Then, symbol judgment processing is performed to filter out high-frequency signal interference, thereby achieving the purpose of correcting the system orientation angle, reducing the degree of coupling between active and reactive components, improving the control accuracy of the system, improving the grid-connected control power factor, reducing the reactive current component in the grid-connected current, and reducing cable heating losses.

[0106] Please refer to Figure 4a-4d The simulation effect of the solution of the present invention is described. The grid-connected converter is targeted at unity power factor control, and the active load current is 90%.

[0107] Figure 4a :0.1-0.16s, the algorithm of this scheme is not used, and the system orientation angle Phase-locked loop angle When there are various factors in the system that affect the accuracy of the phase-locked loop, the phase of the phase-locked loop angle lags, making the grid-connected reactive current When it is greater than 0, the phase of the A-phase grid-connected current lags behind the phase of the A-phase grid-connected voltage.

[0108] Figure 4b : Phase compensation value at 0.2-0.26s Too small, under-compensation state. Grid-connected reactive current It has decreased, but is still greater than 0. The phase of the A-phase grid-connected current lags behind the phase of the A-phase grid-connected voltage, but the phase difference decreases.

[0109] Figure 4c : Phase compensation value at 0.3-0.36s Too large, over-compensation state. Grid-connected reactive current The sign changes and becomes less than 0. The phase of the A-phase grid-connected current is slightly ahead of the phase of the A-phase grid-connected voltage.

[0110] Figure 4d : Phase compensation value at 0.4-0.46s Suitable. Grid-connected reactive current Close to 0. The phase of the A-phase grid-connected current and the phase of the A-phase grid-connected voltage basically coincide, and the grid-connected power factor is 1.

[0111] Second, please refer to Figure 5 The present invention also provides a phase-locked loop correction system, comprising:

[0112] An acquisition module 11 is used to acquire the grid-connected reactive current and the initial phase-locked loop angle of the current calculation cycle;

[0113] A determination module 12 is used to determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle;

[0114] The compensation module 13 is used to superimpose the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle, and use the target phase-locked loop angle as the orientation angle of the current converter system to perform a coordinate transformation operation.

[0115] In an exemplary embodiment, the process of determining a phase compensation value corresponding to a grid-connected reactive current includes:

[0116] Determine the current iteration cycle of the current calculation cycle, and the time length of the iteration cycle is greater than the time length of the calculation cycle;

[0117] Obtaining a correction coefficient for the current iteration cycle; the correction coefficient is determined according to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0118] The phase compensation value is calculated using the correction coefficient, the calculated cycle frequency and the grid cycle angular frequency.

[0119] In an exemplary embodiment, the process of obtaining the correction coefficient of the current iteration cycle includes:

[0120] If the current iteration cycle is the first iteration cycle, determining the correction coefficient of the current iteration cycle to be an initial coefficient corresponding to the sign of the first grid-connected reactive current obtained in the current iteration cycle;

[0121] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is positive, the correction coefficient of the current iteration cycle is determined to be the first coefficient, and the first coefficient is greater than the correction coefficient of the i-1-th iteration cycle, i=2, 3, ..., n, n is the total number of iterations;

[0122] If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is negative, the correction coefficient of the current iteration cycle is determined to be the second coefficient, and the second coefficient is smaller than the correction coefficient of the i-1-th iteration cycle.

[0123] In an exemplary embodiment, the phase-locked loop correction system further includes:

[0124] A judgment module, used for judging whether the first grid-connected reactive current obtained in the i-th iteration period is within a preset accuracy range when the current iteration period is the i-th iteration period, and if so, determining the correction coefficient of the i-th iteration period as the optimal coefficient;

[0125] The process of obtaining the correction coefficient of the current iteration cycle includes:

[0126] If the current iteration cycle is the jth iteration cycle, it is determined that the correction coefficient of the current iteration cycle is the optimal coefficient, i<j≤n.

[0127] In an exemplary embodiment, the phase-locked loop correction system further includes:

[0128] A filtering module, configured to filter the phase compensation value by a first low-pass filter after calculating the phase compensation value by using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency, so as to obtain a target compensation value;

[0129] The process of superimposing the phase compensation value and the initial phase-locked loop angle to obtain the target phase-locked loop angle includes:

[0130] The target compensation value and the initial phase-locked loop angle are superimposed to obtain the target phase-locked loop angle.

[0131] In an exemplary embodiment, the process of determining a phase compensation value corresponding to a grid-connected reactive current includes:

[0132] The grid-connected reactive current is filtered by a second low-pass filter to obtain a target reactive current;

[0133] A phase compensation value corresponding to a target reactive current is determined.

[0134] In an exemplary embodiment, the process of obtaining the grid-connected reactive current of the current calculation cycle includes:

[0135] Determine the type of output filter of the current converter system;

[0136] Obtain the current of the converter machine side in the current calculation cycle;

[0137] Calculate the grid current based on the type and the converter machine-side current;

[0138] The grid-connected reactive current is obtained by performing coordinate transformation on the grid-connected current.

[0139] Third, please refer to Figure 6 The present invention also provides an electronic device, comprising:

[0140] A memory 21, used for storing computer programs;

[0141] The processor 22 is used to implement the steps of the phase-locked loop correction method described in any one of the above embodiments when executing the computer program.

[0142] The electronic device also includes:

[0143] The input interface 23 is connected to the processor 22 via the communication bus 26, and is used to obtain the computer programs, parameters and instructions imported from the outside, and save them in the memory 21 under the control of the processor 22. The input interface can be connected to an input device to receive parameters or instructions manually input by the user. The input device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the terminal housing.

[0144] The display unit 24 is connected to the processor 22 via the communication bus 26 and is used to display the data sent by the processor 22. The display unit can be a liquid crystal display or an electronic ink display.

[0145] The network port 25 is connected to the processor 22 via the communication bus 26, and is used to communicate with various external terminal devices. The communication technology used in the communication connection can be a wired communication technology or a wireless communication technology, such as mobile high-definition link technology, universal serial bus, high-definition multimedia interface, wireless fidelity technology, Bluetooth communication technology, low-power Bluetooth communication technology, communication technology based on IEEE802.11s, etc.

[0146] For an introduction to an electronic device provided by the present invention, please refer to the above embodiments, and the present invention will not be described in detail here.

[0147] The electronic equipment provided by the present invention has the same beneficial effects as the above-mentioned phase-locked loop correction method.

[0148] Fourth, please refer to Figure 7 The present invention further provides a computer-readable storage medium 30, on which a computer program 31 is stored. When the computer program 31 is executed by a processor, the steps of the phase-locked loop correction method described in any one of the embodiments above are implemented.

[0149] The computer-readable storage medium 30 may include: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store the program 31 code.

[0150] For an introduction to a computer-readable storage medium provided by the present invention, please refer to the above embodiments, and the present invention will not be described in detail here.

[0151] A computer-readable storage medium provided by the present invention has the same beneficial effects as the above-mentioned phase-locked loop correction method.

[0152] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, implements the steps of the phase-locked loop correction method described in any one of the embodiments above.

[0153] For an introduction to a computer program product provided by the present invention, please refer to the above embodiments, and the present invention will not be described in detail here.

[0154] A computer program product provided by the present invention has the same beneficial effects as the above-mentioned phase-locked loop correction method.

[0155] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0156] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phase-locked loop calibration method, characterized in that: include: Obtain the grid-connected reactive current and initial phase-locked loop angle of the current calculation cycle; Determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle; The phase compensation value and the initial phase-locked loop angle are superimposed to obtain a target phase-locked loop angle, and the target phase-locked loop angle is used as the orientation angle of the current converter system to perform a coordinate transformation operation.

2. The phase-locked loop calibration method according to claim 1, characterized in that: The process of determining the phase compensation value corresponding to the grid-connected reactive current includes: Determine the current iteration period in which the current calculation period is located, and the time length of the iteration period is greater than the time length of the calculation period; Obtaining a correction coefficient for the current iteration cycle; the correction coefficient is determined according to the sign of the first grid-connected reactive current obtained in the current iteration cycle; The phase compensation value is calculated using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency.

3. The phase-locked loop calibration method according to claim 2, characterized in that: The process of obtaining the correction coefficient of the current iteration cycle includes: If the current iteration cycle is the first iteration cycle, determining the correction coefficient of the current iteration cycle to be an initial coefficient corresponding to the sign of the first grid-connected reactive current obtained in the current iteration cycle; If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is positive, determine that the correction coefficient of the current iteration cycle is the first coefficient, and the first coefficient is greater than the correction coefficient of the i-1-th iteration cycle, i=2, 3, ..., n, n is the total number of iterations; If the current iteration cycle is the i-th iteration cycle, and the sign of the first grid-connected reactive current obtained in the current iteration cycle is negative, the correction coefficient of the current iteration cycle is determined to be the second coefficient, and the second coefficient is smaller than the correction coefficient of the i-1-th iteration cycle.

4. The phase-locked loop calibration method according to claim 3, characterized in that: The phase-locked loop correction method also includes: If the current iteration cycle is the i-th iteration cycle, determining whether the first grid-connected reactive current obtained in the i-th iteration cycle is within a preset accuracy range; If so, determining the correction coefficient of the i-th iteration cycle as the optimal coefficient; The process of obtaining the correction coefficient of the current iteration cycle includes: if the current iteration cycle is the jth iteration cycle, determining the correction coefficient of the current iteration cycle as the optimal coefficient, i<j≤n.

5. The phase-locked loop calibration method according to claim 2, characterized in that: After calculating the phase compensation value using the correction coefficient, the calculation cycle frequency and the grid cycle angular frequency, the phase-locked loop correction method further includes: Filtering the phase compensation value through a first low-pass filter to obtain a target compensation value; The process of superimposing the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle includes: The target compensation value and the initial phase-locked loop angle are superimposed to obtain a target phase-locked loop angle.

6. The phase-locked loop calibration method according to claim 1, characterized in that: The process of determining the phase compensation value corresponding to the grid-connected reactive current includes: Filtering the grid-connected reactive current through a second low-pass filter to obtain a target reactive current; A phase compensation value corresponding to the target reactive current is determined.

7. The phase-locked loop calibration method according to any one of claims 1 to 6, characterized in that: The process of obtaining the grid-connected reactive current of the current calculation period includes: Determining a type of output filter of the current converter system; Obtaining the converter machine-side current of the current calculation cycle; Calculating the grid-connected current based on the type and the converter machine-side current; The grid-connected reactive current is obtained by performing the coordinate transformation operation on the grid-connected current.

8. A phase-locked loop correction system, characterized in that: include: An acquisition module is used to obtain the grid-connected reactive current and the initial phase-locked loop angle of the current calculation cycle; A determination module, used to determine a phase compensation value corresponding to the grid-connected reactive current; the sign of the phase compensation value changes with the sign of the grid-connected reactive current in the current calculation cycle; The compensation module is used to superimpose the phase compensation value and the initial phase-locked loop angle to obtain a target phase-locked loop angle, and use the target phase-locked loop angle as the orientation angle of the current converter system to perform a coordinate transformation operation.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the phase-locked loop correction method as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the phase-locked loop correction method according to any one of claims 1 to 7 are implemented.

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