Alternating current and direct current harmonic numerical calculation method, device and equipment of three-pulse converter

Abstract

The invention relates to an alternating current and direct current harmonic numerical value calculation method, device and equipment of a three-pulse converter. The method comprises the following steps: acquiring an electrical quantity parameter, a power frequency period and a calculation point number of a three-pulse converter unit in the converter; dividing the power frequency period into six calculation stages; determining a calculation point voltage according to the calculation point number and the electrical quantity parameter; determining a discrete calculation starting point and a discrete calculation ending point according to the a-phase trigger angle and the calculation point number; according to the calculation point number, the discrete calculation starting point and the discrete calculation ending point, determining the current calculation point marking quantity, the previous-step calculation point marking quantity and the calculation point variable; if the calculation point variable is not greater than the calculation point number, determining a parameter calculation rule and a calculation stage of a next calculation point according to a calculation stage; obtaining a direct-current voltage until the calculation point variable is greater than the calculation point number; and processing all the DC voltages to obtain voltage harmonic data. The method can accurately calculate the direct-current voltage harmonic waves, and the harmonic wave calculation mode is simple, the calculation speed is high, and calculation is accurate.

Description

Technical Field

[0001] This application relates to the field of converter technology, and in particular to a method, apparatus and equipment for numerical calculation of AC and DC harmonics of a three-pulse converter. Background Technology

[0002] In power systems, high-voltage direct current (HVDC) transmission systems based on thyristor converters remain an important mode of long-distance, high-capacity power transmission. As the core equipment of HVDC transmission systems, the harmonic characteristics of thyristor converters directly affect the power quality, equipment insulation lifespan, and stable operation of the power grid. With the large-scale grid connection of new energy sources and increasingly complex load characteristics, the background harmonics of the AC power grid exhibit characteristics such as large amplitude fluctuations and complex frequency components. Traditional harmonic calculation methods for thyristor converters have revealed many shortcomings when considering the impact of background harmonics in the AC power grid.

[0003] In DC-side harmonic calculations for DC transmission systems, converter valve groups are often treated as equivalent to a three-pulsating harmonic voltage source. Besides the characteristic harmonics of the thyristor converter, non-characteristic harmonics caused by non-ideal factors also need to be considered in the calculations. These non-ideal factors mainly include firing angle asymmetry, phase-to-phase impedance asymmetry, winding deviation, AC voltage imbalance, and AC-side background harmonic voltage. In existing technologies, a cycle is typically segmented based on the commutation angle at each commutation moment. During each commutation process, the voltage and current of the commutation stage are analytically solved using differential equations to obtain the switching time of each segment. However, the commutation process of a three-pulsating converter unit is affected by many factors. Current analytical solutions to differential equations only consider the three-phase AC voltage at the power frequency. If the three-phase AC voltage contains high-frequency background harmonics, these background harmonics will affect the commutation process, making existing analytical solutions unsuitable. If higher-order background harmonics are considered when establishing differential equations, analytical solutions become too complex and impractical.

[0004] The existing scheme for calculating AC / DC harmonics in a three-pulsating converter unit involves deriving the differential equations for the commutation period based on the equivalent circuit of the unit. The analytical solutions are then obtained from the general and particular solutions of the homogeneous differential equations, leading to the commutation angle and solutions for other voltages and currents. However, this method only considers the fundamental frequency component of the three-phase AC voltage in its commutation process. If the three-phase AC voltage contains background harmonics, the resulting differential equations become extremely complex, making it difficult to obtain accurate analytical solutions and resulting in poor accuracy in calculating AC / DC harmonics for the three-pulsating converter unit. Summary of the Invention

[0005] This application provides a numerical calculation method, apparatus, and equipment for AC / DC harmonics of a three-pulse converter, which solves the technical problem that the existing AC / DC harmonic calculation method for three-pulse units is difficult to solve analytically when considering the background harmonics of three-phase AC voltage, resulting in poor accuracy of AC / DC harmonic calculation results.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] On the one hand, a numerical calculation method for AC / DC harmonics of a three-pulse converter is provided, including the following steps:

[0008] Obtain the electrical parameters, power frequency period, and number of calculation points of the three-pulse converter unit in the converter; and divide the power frequency period into six calculation stages; the six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage calculated by ring cyclic switching;

[0009] Based on the number of calculation points and the electrical quantity parameters, determine the three-phase calculation point voltage for each calculation point; based on the a-phase firing angle of the electrical quantity parameters and the number of calculation points, determine the discrete calculation start point and discrete calculation end point;

[0010] Based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point, determine the current calculation point marker, the previous calculation point marker, and the calculation point variable;

[0011] Using the first commutation calculation stage as the initial calculation stage, if the calculation point variable is not greater than the number of calculation points, the parameter calculation rules and the calculation stage for cyclically calculating the next calculation point are determined according to the calculation stage corresponding to the current calculation point marker; until the calculation point variable is greater than the number of calculation points, the DC voltage corresponding to the number of calculation points is obtained;

[0012] All the DC voltages are processed to obtain the AC and DC voltage harmonic data of the three-pulse converter unit;

[0013] Wherein, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained; the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameter; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameter and the three-phase calculation point voltage.

[0014] If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage.

[0015] Optionally, the electrical quantity parameters include a three-phase AC voltage containing multiple positive-sequence voltage components, positive-sequence voltage component phase angles, negative-sequence voltage components, and negative-sequence voltage component phase angles. Determining the calculation point voltage of the three phases at each calculation point based on the number of calculation points and the electrical quantity parameters includes: calculating the calculation point voltage of the three phases corresponding to each calculation point based on the value of each calculation point and all the positive-sequence voltage components, positive-sequence voltage component phase angles, negative-sequence voltage components, and negative-sequence voltage component phase angles.

[0016] Optionally, determining the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point includes:

[0017] Using the discrete calculation starting point as the initial calculation point variable, the value of the calculation point variable is incremented by 1 for each calculation;

[0018] If the calculated point variable is not greater than the number of calculated points, then the calculated point variable is used as the current calculated point marker; if the calculated point variable is greater than the number of calculated points, then the difference between the calculated point variable and the number of calculated points is used as the current calculated point marker.

[0019] If the current calculation point marker quantity is greater than the initial calculation point marker quantity, then the difference between the current calculation point marker quantity and the initial calculation point marker quantity is used as the previous calculation point marker quantity; if the current calculation point marker quantity is equal to the initial calculation point marker quantity, then the calculation point quantity is used as the previous calculation point marker quantity.

[0020] Optionally, the electrical quantity parameters include the equivalent resistance of phase a, the equivalent inductance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase b, the equivalent resistance of phase c, and the equivalent inductance of phase c; the calculation point voltages of the three phases include the calculation point voltages of phase a, phase b, and phase c; if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the calculation point voltages of the three phases, including:

[0021] If the commutation current corresponding to the current calculation point marker is greater than the DC output current, then the calculation stage of the next calculation point is the corresponding second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage.

[0022] If the commutation current corresponding to the current calculation point marker is not greater than the DC output current, then the calculation stage of the next calculation point is still the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage.

[0023] If the calculation stage corresponding to the current calculation point mark is the first commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase c, and the calculation point voltage of phase a and phase c corresponding to the current calculation point mark.

[0024] If the calculation stage corresponding to the current calculation point mark is the third commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase b, and the calculation point voltages of phase a and phase b corresponding to the current calculation point mark.

[0025] If the calculation stage corresponding to the current calculation point marker is the fifth commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point marker based on the b-phase equivalent inductance, the c-phase equivalent inductance, and the b-phase calculation point voltage and the c-phase calculation point voltage corresponding to the current calculation point marker.

[0026] Optionally, the electrical quantity parameters include the phase b firing angle and the phase c firing angle, and the three-phase calculation point voltages include the phase a calculation point voltage, the phase b calculation point voltage, and the phase c calculation point voltage; if the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltages, including:

[0027] When the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the trigger angle judgment data is obtained based on the calculation point variable and the number of calculation points; the first trigger angle threshold, the second trigger angle threshold, and the third trigger angle threshold corresponding to the second non-commutation calculation stage, the fourth non-commutation calculation stage, and the sixth non-commutation calculation stage are calculated based on the b-phase trigger angle, the c-phase trigger angle, and the a-phase trigger angle, respectively.

[0028] If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is not less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point is the corresponding third commutation calculation stage, fifth commutation calculation stage, or first commutation calculation stage.

[0029] If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point is still the corresponding second non-commutation calculation stage, fourth non-commutation calculation stage, or sixth non-commutation calculation stage.

[0030] If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, then the parameter calculation rule is to take the voltage of the a-phase calculation point corresponding to the current calculation point marker as the DC voltage of the current calculation point marker.

[0031] If the calculation stage corresponding to the current calculation point marker is the fourth non-commutation calculation stage, then the parameter calculation rule is to take the b-phase calculation point voltage corresponding to the current calculation point marker as the DC voltage of the current calculation point marker.

[0032] If the calculation stage corresponding to the current calculation point marker is the sixth non-commutation calculation stage, then the parameter calculation rule is to use the c-phase calculation point voltage corresponding to the current calculation point marker as the DC voltage of the current calculation point marker.

[0033] Optionally, obtaining the commutation current of the current calculation point marker includes:

[0034] The discrete calculation step size is determined based on the power frequency period and the number of calculation points;

[0035] Based on the electrical quantity parameters and the discrete calculation step size, the first discrete coefficient, the second discrete coefficient, and the third discrete coefficient are determined.

[0036] Obtain the commutation data of the previous calculation point marker, the commutation data including the commutation current, phase a commutation voltage and phase c commutation voltage of the previous calculation point;

[0037] Based on the first discrete coefficient, the second discrete coefficient, the third discrete coefficient, the previous commutation data, the DC output current, and the calculation point voltage of the three phases at the current calculation point, determine the commutation current corresponding to the current calculation point marker.

[0038] Optionally, the electrical quantity parameters include the equivalent resistance of phase a, the equivalent inductance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase b, the equivalent resistance of phase c, and the equivalent inductance of phase c. Determining the first, second, and third discrete coefficients based on the electrical quantity parameters and the discrete calculation step size includes:

[0039] The first discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase c, the equivalent inductance of phase a, and the equivalent inductance of phase c.

[0040] The second discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase a, and the equivalent inductance of phase b.

[0041] The third discrete coefficient is obtained by calculating the discrete calculation step size, the c-phase equivalent resistor, the b-phase equivalent resistor, the c-phase equivalent inductor, and the b-phase equivalent inductor.

[0042] Optionally, if the number of calculation points is denoted as N, the voltage harmonic data of the AC and DC circuits of the three-pulse converter unit are obtained by processing all the DC voltages, including:

[0043] All the DC voltages are used to form a DC voltage waveform. The DC voltage waveform is then converted to the frequency domain using a fast Fourier transform to obtain the frequency domain voltage data corresponding to each DC voltage in complex form.

[0044] The first to the N / 2nd frequency domain voltage data are used as the first to the N / 2nd AC / DC voltage harmonic data of the three-pulse converter unit.

[0045] On the other hand, a numerical calculation device for AC / DC harmonics of a three-pulse converter is provided, including a data acquisition module, a first calculation module, a second calculation module, a voltage calculation module, and a harmonic determination module;

[0046] The data acquisition module is used to acquire electrical parameters, power frequency cycle, and number of calculation points of the three-pulse converter unit in the converter; and to divide the power frequency cycle into six calculation stages; the six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage, which are calculated by ring-cycle switching.

[0047] The first calculation module is used to determine the three-phase calculation point voltage of each calculation point based on the number of calculation points and the electrical quantity parameters; and to determine the discrete calculation start point and discrete calculation end point based on the a-phase firing angle of the electrical quantity parameters and the number of calculation points.

[0048] The second calculation module is used to determine the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point.

[0049] The voltage calculation module is used to take the first commutation calculation stage as the initial calculation stage. If the calculation point variable is not greater than the number of calculation points, it determines the parameter calculation rules and the calculation stage for cyclically calculating the next calculation point according to the calculation stage corresponding to the current calculation point marker. This continues until the calculation point variable is greater than the number of calculation points, and then obtains the DC voltage corresponding to the number of calculation points.

[0050] The harmonic determination module is used to process all the DC voltages to obtain the AC and DC voltage harmonic data of the three-pulse converter unit.

[0051] Wherein, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameter; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameter and the three-phase calculation point voltage.

[0052] If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage.

[0053] On the other hand, a terminal device is provided, including a processor and a memory;

[0054] The memory is used to store program code and transmit the program code to the processor;

[0055] The processor is configured to execute the AC / DC harmonic numerical calculation method for the three-pulse converter as described above, according to the instructions in the program code.

[0056] The present invention discloses a numerical calculation method, apparatus, and equipment for AC / DC harmonics in a three-pulse converter. The method includes obtaining the electrical quantity parameters, power frequency cycle, and number of calculation points of the three-pulse converter unit in the converter; dividing the power frequency cycle into six calculation stages; the six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage using a circular cyclic switching calculation; determining the calculation point voltage of the three phases at each calculation point based on the number of calculation points and electrical quantity parameters; determining the discrete calculation start point and discrete calculation end point based on the a-phase trigger angle and the number of calculation points; determining the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point; using the first commutation calculation stage as the initial calculation stage, if the calculation point variable is not greater than the number of calculation points, determining the parameter calculation rules based on the calculation stage corresponding to the current calculation point marker. The calculation process iterates through the next calculation point until the calculation point variable exceeds the number of calculation points, obtaining the DC voltage corresponding to the number of calculation points. All DC voltages are processed to obtain the AC / DC voltage harmonic data for the three-pulse converter unit. If the calculation stage corresponding to the current calculation point marker is the first, third, or fifth commutation calculation stage, the commutation current of the current calculation point marker is obtained. The calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters. The parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the three-phase calculation point voltages. If the calculation stage corresponding to the current calculation point marker is the second, fourth, or sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined based on the calculation point variable, the number of calculation points, and the electrical quantity parameters. The parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltages.

[0057] As can be seen from the above technical solutions, this application has the following advantages: The numerical calculation method for AC / DC harmonics of the three-pulse converter uses discrete processing of electrical parameters to obtain the calculation point voltages of the three phases. Then, based on the calculation point data and the corresponding calculation point voltages of all three phases, the harmonics are solved in stages. In the discrete numerical solution of the commutation process, the DC voltage under the background harmonics of the three-phase AC voltage can be naturally calculated, and the accurate DC voltage harmonic calculation results of the three-pulse converter unit can be obtained. This harmonic calculation method is simple, fast, and accurate. It solves the technical problem that the existing AC / DC harmonic calculation method of the three-pulse unit is difficult to solve analytically when considering the background harmonics of the three-phase AC voltage, resulting in poor accuracy of the AC / DC harmonic calculation results.

[0058] The AC / DC harmonic numerical calculation device of this three-pulse converter discretizes electrical parameters through a data acquisition module, a first calculation module, a second calculation module, a voltage calculation module, and a harmonic determination module to obtain the three-phase calculation point voltages. Then, based on the calculation point data and the corresponding three-phase calculation point voltages, it performs staged harmonic solutions. During the discrete numerical solution commutation process, the DC voltage under the background harmonics of the three-phase AC voltage can be naturally calculated, and the accurate DC voltage harmonic calculation results of the three-pulse converter unit can be obtained. This harmonic calculation method is simple, fast, and accurate. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 This is a flowchart illustrating the steps of the AC / DC harmonic numerical calculation method for a three-pulse converter described in this application embodiment;

[0061] Figure 2 This is a schematic diagram of the topology of the three-pulsating converter unit in the AC / DC harmonic numerical calculation method of the three-pulsating converter described in the embodiments of this application;

[0062] Figure 3 This is an equivalent circuit diagram of the commutation process from phase C to phase A in the AC / DC harmonic numerical calculation method for the three-pulse converter described in the embodiments of this application.

[0063] Figure 4 This is a schematic diagram of the frame of the AC / DC harmonic numerical calculation device for the three-pulse converter described in the embodiments of this application;

[0064] Figure 5 This is a schematic diagram of the terminal device described in an embodiment of this application. Detailed Implementation

[0065] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0066] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0067] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0068] Patent terminology:

[0069] The Fast Fourier Transform (FFT) performs spectral analysis through discrete operations. Its core algorithm converts time-domain signals into frequency-domain signals and can quickly calculate the Discrete Fourier Transform (DFT) or its inverse transform.

[0070] The ROUND function rounds a number to a given number of digits. ROUND rounds up when the last significant digit is 5 or greater, and rounds down when the last significant digit is less than 5.

[0071] This application provides a method, apparatus, and device for numerically calculating AC / DC harmonics in a three-pulsating converter. It solves the technical problem that existing methods for calculating AC / DC harmonics in three-pulsating units suffer from high difficulty in finding analytical solutions to the differential equations when considering background harmonics in three-phase AC voltage, leading to poor accuracy in the calculated results. The method, apparatus, and device for numerically calculating AC / DC harmonics in a three-pulsating converter are illustrated using a converter comprising one three-pulsating converter unit as an example.

[0072] Example 1:

[0073] Figure 1 This is a flowchart illustrating the steps of the AC / DC harmonic numerical calculation method for a three-pulse converter described in this application embodiment. Figure 2 This is a schematic diagram of the topology of the three-pulsating converter unit in the AC / DC harmonic numerical calculation method of the three-pulsating converter described in the embodiments of this application.

[0074] like Figure 1 As shown in the figure, this application provides a method for numerically calculating AC and DC harmonics in a three-pulse converter, including the following steps:

[0075] S1. Obtain the electrical parameters, power frequency period, and number of calculation points of the three-pulse converter unit in the converter; and divide the power frequency period into six calculation stages; the six calculation stages include the first commutation calculation stage, the second non-commutation calculation stage, the third commutation calculation stage, the fourth non-commutation calculation stage, the fifth commutation calculation stage, and the sixth non-commutation calculation stage, which are calculated by ring-shaped cyclic switching.

[0076] It should be noted that in the process of calculating the AC / DC harmonic values ​​of the three-pulse converter, in step S1, the electrical quantity parameters of the three-pulse converter unit in the converter can be obtained from the power grid operation management system according to the set power frequency cycle T1. The number of calculation points for one power frequency cycle T1 is set to N, and the power frequency cycle T1 is divided into six calculation stages, including commutation and non-commutation stages, to provide data for the next step. This can be understood as follows: in AC / DC harmonic calculation, obtaining the electrical quantity parameters, power frequency cycle, and number of calculation points of the three-pulse converter unit in the converter, and dividing the power frequency cycle into six calculation stages (including three commutation calculation stages and three non-commutation calculation stages under the ring-loop switching calculation), can significantly improve the accuracy, completeness, and practicality of harmonic analysis, providing a reliable basis for harmonic suppression and calculation optimization. In this embodiment, the electrical quantity parameters include three-phase AC voltage containing multiple positive-sequence voltage components, positive-sequence voltage component phase angles, negative-sequence voltage components, and negative-sequence voltage component phase angles, and the equivalent resistance R of phase a. a Equivalent inductance L of phase a a Equivalent resistor R of phase b b Equivalent inductance L of phase b b Equivalent resistor R of phase c c c-phase equivalent inductance L c The data includes the firing angles α1 (phase a), α3 (phase b), and α5 (phase c). The calculation mode, based on a circular switching mechanism, works as follows: the second non-commutation calculation stage switches to the next calculation point after the first commutation calculation stage; the third commutation calculation stage switches to the next calculation point after the second non-commutation calculation stage; the fourth non-commutation calculation stage switches to the next calculation point after the third commutation calculation stage; the fifth commutation calculation stage switches to the next calculation point after the fourth non-commutation calculation stage; the sixth non-commutation calculation stage switches to the next calculation point after the sixth non-commutation calculation stage; and the first commutation calculation stage switches back to the next calculation point after the sixth non-commutation calculation stage. This reasonable determination of the number of calculation points ensures that harmonics of different frequencies can be fully analyzed.

[0077] In this embodiment, the three-phase AC voltage can be understood as the effective value of the nth positive sequence voltage component of the three-phase AC voltage, U. s1 (n), the phase angle of the nth positive sequence voltage component is θ s1 (n), the effective value of the nth negative sequence voltage component is U s2The phase angle between (n) and the nth negative sequence voltage component is θ s2 (n), where 1≤n≤25.

[0078] In this embodiment, dividing the power frequency cycle into six calculation stages, including commutation and non-commutation, can be understood as follows: In the commutation calculation stage, due to the sudden changes in current and voltage when the converter is turned on / off, high-frequency harmonic components are generated. By calculating harmonics in segments, the influence of parameters such as commutation angle and firing angle on the harmonic amplitude and phase can be accurately captured. In the non-commutation calculation stage, the harmonic components of the converter are relatively stable under steady-state operation, but non-ideal factors such as DC current ripple and AC voltage distortion need to be considered. Calculating harmonics in segments helps to separate the harmonic contributions under different operating conditions and improves the accuracy of harmonic calculation.

[0079] For example, step S1 can be understood as obtaining various electrical parameters, power frequency cycle duration, and the number of points required for calculation of the three-pulse converter unit in the converter; at the same time, the power frequency cycle is divided into six calculation stages including commutation and non-commutation, so that the three-pulse converter unit in the converter can predict the harmonic level under different operating conditions through segmented calculation.

[0080] S2. Based on the number of calculation points and electrical quantity parameters, determine the three-phase calculation point voltage for each calculation point; based on the a-phase firing angle and the number of calculation points of the electrical quantity parameters, determine the discrete calculation start point and discrete calculation end point.

[0081] It should be noted that step S2, based on the number of calculation points and electrical quantity parameters obtained in step S1, accurately determines the calculation point voltage of each phase corresponding to the three phases. Simultaneously, combining the a-phase trigger angle α1 in the electrical quantity parameters and the predetermined number of calculation points N, it clearly defines the starting position (e.g., the starting point of the discrete calculation) and the ending position (e.g., the ending point of the discrete calculation). The three-phase calculation point voltage includes the a-phase calculation point voltage u. a (k), b-phase calculation point voltage u b (k) and c-phase calculated point voltage u c (k). In this embodiment, the discrete calculation start point and discrete calculation end point are obtained by using the point position formula based on the a-phase firing angle α1 of the electrical quantity parameter and the number of calculation points N. The point position formula is:

[0082]

[0083]

[0084] In the formula, k s As the starting point for discrete computation, k e This is the endpoint of discrete computation.

[0085] For example, in step S2, based on the given number of calculation points and the electrical parameters of the three-pulsating converter unit within the converter, the calculated voltage of the three phases at each calculation point can be accurately derived using specific calculation methods and theoretical models. Furthermore, using the a-phase firing angle from the electrical parameters and the known number of calculation points, relevant algorithms are applied to determine the start and end points of the discrete calculation process. In other embodiments, firstly, the obtained number of calculation points and various electrical parameters contained in the three-pulsating converter unit within the converter are fully utilized, and appropriate circuit theory and mathematical calculation methods are applied to accurately determine the three-phase voltage values ​​corresponding to each calculation point. Secondly, based on the key parameter of the a-phase firing angle from the electrical parameters, combined with the already determined number of calculation points, specific calculation rules are used to clearly determine the starting calculation point (i.e., the discrete calculation start point) and the ending calculation point (i.e., the discrete calculation end point) of the discrete calculation process.

[0086] S3. Based on the number of calculation points, the starting point of discrete calculation, and the ending point of discrete calculation, determine the current calculation point marker, the previous calculation point marker, and the calculation point variable.

[0087] It should be noted that step S3 is based on the number of calculation points, the starting position of discrete calculation (discrete calculation start point), and the ending position of discrete calculation (discrete calculation end point) given in steps S1 and S2. It uses pre-set logical rules to calculate and accurately determine the identifier of the current calculation point (i.e., the current calculation point label), the identifier of the previous calculation point (i.e., the previous step calculation point label), and the variables used to characterize the features of the calculation point or participate in subsequent calculations (i.e., calculation point variables).

[0088] Understandably, in AC / DC harmonic calculations, harmonics in a power system dynamically change over time, with variations in harmonic components and amplitudes at different moments. This numerical calculation method for AC / DC harmonics in a three-pulse converter, by clearly defining the number of calculation points, allows for detailed division of time intervals, enabling harmonic analysis within each time period. The discrete calculation start and end points define the calculation time range. The current calculation point marker accurately identifies the moment being analyzed, while the previous calculation point marker records information from the previous calculation point, precisely tracking harmonic changes from the previous point to the current one. This avoids calculation errors caused by coarsely divided discrete calculation points and comprehensively covers harmonics across all frequency bands, preventing the omission of important harmonic components. For example, when analyzing harmonics generated by the converter, the switching on and off of the converter valve causes sudden changes in current and voltage, generating rich harmonic components. By using the current calculation point marker, the previous calculation point marker, and calculation point variables, the harmonic characteristics of these abrupt calculation points can be accurately captured, improving the accuracy of the calculation results.

[0089] S4. Taking the first commutation calculation stage as the initial calculation stage, if the calculation point variable is not greater than the number of calculation points, determine the parameter calculation rules and iteratively calculate the next calculation point stage according to the calculation stage corresponding to the current calculation point marker; until the calculation point variable is greater than the number of calculation points, obtain the DC voltage corresponding to the number of calculation points. Specifically, if the calculation stage corresponding to the current calculation point marker is the first, third, or fifth commutation calculation stage, obtain the commutation current of the current calculation point marker, and determine the calculation stage of the next calculation point by comparing the commutation current with the DC output current of the electrical quantity parameters; the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters, commutation current, and the three-phase calculation point voltages. If the calculation stage corresponding to the current calculation point marker is the second, fourth, or sixth non-commutation calculation stage, determine the next calculation point stage according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the DC output current and the three-phase calculation point voltages.

[0090] It should be noted that when performing harmonic calculations based on the number of calculation points N, the first commutation calculation stage is used as the initial calculation stage, and the initial calculation point variable k is set to... loop The starting point is set to the discrete calculation starting point k. s This causes the calculation point variable of the loop to start from the discrete calculation starting point k. s To the discrete computation endpoint k e The value is incremented by 1 point at a time. Based on whether the current calculation point marker k determined in step S3 is not greater than the number of calculation points N, if so, the DC voltage u corresponding to the current calculation point marker k is calculated using different pre-set rules based on the calculation stage corresponding to the current calculation point marker k. mo (k), each time the numerical calculation point variable k is calculated, is used. loop Add 1 until the point variable k is calculated. loop If the number of calculation points is greater than N, then the DC voltage u corresponding to N calculation points is obtained. mo This provides data for accurately calculating the DC harmonics of the converter. In this embodiment, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current i is obtained by recursively calculating each current calculation point marker k. r (k), based on the commutation current i r (k) and the known DC output current I of the converter dThe relationship between the current calculation point and the next calculation stage is determined. The DC voltage corresponding to the current calculation point marker k is calculated based on the electrical quantity parameters obtained in step S1 and the three-phase calculation point voltages determined in step S2. If the calculation stage corresponding to the current calculation point marker k is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation point variable k determined in step S3 is used as the basis for the calculation. loop And the number of calculation points N obtained in step S1 is first determined according to the variable k of the calculation points. loop The relationship between the changing judgment data and the known electrical parameters of the converter determines the firing angle threshold. It is then used to determine whether to switch to the next calculation stage. The DC voltage of the current calculation point marker k is also calculated based on the three-phase calculation point voltage determined in step S2.

[0091] For example, in the process of harmonic calculation based on the number of calculation points N, step S4 can be understood as setting the first commutation calculation stage as the initial calculation stage. The value k of the calculation point variable... loop If the number of calculation points N is not exceeded, the parameter calculation rules are determined based on the calculation stage corresponding to the current calculation point's marker k, and the calculation stage of the next calculation point is derived iteratively. This process continues until the value k of the calculation point variable is reached. loop The calculation exceeds the number of calculation points N, thus deriving a DC voltage that matches the number of calculation points. Specifically, if the calculation stage corresponding to the current calculation point marker k is the first, third, or fifth commutation calculation stage, the commutation current i of that current calculation point marker k needs to be obtained. r (k), by passing the commutation current i r (k) and the DC output current I in the electrical quantity parameters d By comparing the results, the next calculation stage is determined. At this point, the parameter calculation rule is as follows: Taking into account the electrical quantity parameters, commutation current, and the three-phase calculation point voltages, the DC voltage u corresponding to the current calculation point marker k is calculated. mo (k). If the calculation stage corresponding to the current calculation point marker k is the second, fourth, or sixth non-commutation calculation stage, then the calculation stage of the next calculation point is determined based on the calculation point variables, the number of calculation points, and the electrical quantity parameters. In this case, the parameter calculation rule is: calculate the value relative to the current calculation point marker I based on the three-phase calculation point voltage. d The corresponding DC voltage u mo (k).

[0092] In this embodiment of the application, if the calculation stage corresponding to the current calculation point marker k is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, the commutation current i of the current calculation point marker k can be used as a reference. r (k) and DC output current I dCalculate the AC current of the current calculation point marker k. If the calculation stage corresponding to the current calculation point marker k is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the DC output current I can be used as a reference. d The calculation yields the AC current of the current calculation point marker k, providing data for accurate calculation of AC current harmonics in the converter.

[0093] It should be noted that if the calculation stage corresponding to the current calculation point marker k is the first commutation calculation stage, the DC output current I will be... d The commutation current i relative to the current calculation point marker k r The difference between (k) and the current point marker k corresponds to the c-phase AC current i. c (k), that is The current b-phase AC current i at the current calculation point marker k. b (k) is set to 0, that is The commutation current i of the current calculation point marker k. r (k) represents the a-phase AC current i corresponding to the current calculation point marker k. a (k), that is If the calculation stage corresponding to the current calculation point marker k is the third commutation calculation stage, then the DC output current I will be... d The commutation current i relative to the current calculation point marker k r The difference between (k) and the current calculation point marker k corresponds to the a-phase AC current i. a (k), that is The commutation current i of the current calculation point marker k. r (k) represents the b-phase AC current i corresponding to the current calculation point marker k. b (k), that is The current c-phase AC current i at the current calculation point marker k. c (k) is set to 0. If the calculation stage corresponding to the current calculation point marker k is the fifth commutation calculation stage, the DC output current I is set to 0. d The commutation current i relative to the current calculation point marker k r The difference between (k) and the current value k is the b-phase AC current i corresponding to the current calculation point marker k. b (k), that is The commutation current i of the current calculation point marker k. r (k) represents the c-phase AC current i corresponding to the current calculation point marker k. c (k), that is The current a-phase AC current i at the current calculation point marker k. a (k) is set to 0. If the calculation stage corresponding to the current calculation point marker k is the second non-commutation calculation stage, the DC output current I is set to 0.d As the a-phase alternating current i corresponding to the current calculation point marker k a (k), that is ;The b-phase AC current i of the current calculation point marker k b (k) and c-phase AC current i c (k) are all set to 0. If the calculation stage corresponding to the current calculation point marker k is the fourth non-commutation calculation stage, the DC output current I is set to 0. d As the b-phase alternating current i corresponding to the current calculation point marker k b (k), that is ;The a-phase AC current i of the current calculation point marker k a (k) and c-phase AC current i c (k) are all set to 0. If the calculation stage corresponding to the current calculation point marker k is the sixth non-commutation calculation stage, the DC output current I is set to 0. d As the c-phase alternating current i corresponding to the current calculation point marker k c (k), that is ;The b-phase AC current i of the current calculation point marker k b (k) and phase a alternating current i a (k) are all set to 0.

[0094] S5. Process all DC voltages to obtain the AC and DC voltage harmonic data of the three-pulse converter unit.

[0095] It should be noted that step S5 is based on the N DC voltages obtained in step S5, which are then subjected to a series of operations (such as filtering, transformation, etc.). Taking into full account the special structure and operating characteristics of the three-pulse converter unit, the voltage harmonic data corresponding to the three-pulse converter unit is obtained. This voltage harmonic data can accurately reflect the key information such as the harmonic components, amplitude, and phase in the AC and DC voltages and currents. In this embodiment, the AC and DC harmonic numerical calculation method of the three-pulse converter will also construct AC current waveforms for all AC currents, and perform frequency domain conversion on the AC current waveforms using fast Fourier transform to obtain frequency domain current data represented in complex form corresponding to each AC current; the frequency domain current data from the 1st to the N / 2nd harmonics are used as the current harmonic data from the 1st to the N / 2nd harmonics of the three-pulse converter unit.

[0096] In this embodiment of the application, all DC voltages are processed to obtain the AC / DC voltage harmonic data of the three-pulse converter unit, including:

[0097] All DC voltages are used to form a DC voltage waveform. The DC voltage waveform is then converted to the frequency domain using a fast Fourier transform to obtain the frequency domain voltage data corresponding to each DC voltage in complex form.

[0098] The first to N / 2 frequency domain voltage data are used as the first to N / 2 AC / DC voltage harmonic data of the three-pulse converter unit.

[0099] It should be noted that a DC voltage u is used. mo The Fast Fourier Transform (FFT) module takes N data points of periodic waveform values ​​as input and performs frequency domain transformation on the N DC voltage data points to obtain N complex frequency domain transformation results (i.e., frequency domain voltage data). The 1st to N / 2nd complex frequency domain transformation results are the 1st to N / 2nd voltage harmonic data of the DC voltage. The magnitude of each complex data point represents the amplitude of the corresponding harmonic, and the argument of each complex number represents the phase angle of the corresponding harmonic.

[0100] In the embodiments of this application, the AC / DC harmonic numerical calculation method for the three-pulse converter employs discrete numerical methods for harmonic solving. During the discrete numerical solution of the commutation process, the background harmonics of the three-phase AC voltage can be naturally taken into account, resulting in accurate commutation angles and voltage and current waveforms during the commutation process, and thus accurate DC voltage harmonic calculation results for the three-pulse converter unit. This AC / DC harmonic numerical calculation method for the three-pulse converter has the advantages of simple calculation method, fast calculation speed, and accurate calculation.

[0101] This application provides a numerical calculation method for AC / DC harmonics in a three-pulse converter, comprising: acquiring electrical quantity parameters, power frequency period, and number of calculation points of the three-pulse converter unit in the converter; dividing the power frequency period into six calculation stages; the six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage using a circular cyclic switching calculation method; determining the calculation point voltage of the three phases at each calculation point based on the number of calculation points and electrical quantity parameters; determining the discrete calculation start point and discrete calculation end point based on the a-phase trigger angle and the number of calculation points; determining the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point; using the first commutation calculation stage as the initial calculation stage; if the calculation point variable is not greater than the number of calculation points, determining the parameter calculation rules and cyclically calculating the next calculation stage based on the calculation stage corresponding to the current calculation point marker; The calculation phase of the point continues until the calculation point variable is greater than the number of calculation points, obtaining the DC voltage corresponding to the number of calculation points; all DC voltages are processed to obtain the AC and DC voltage harmonic data of the three-pulse converter unit; if the calculation phase corresponding to the current calculation point marker is the first commutation calculation phase, the third commutation calculation phase, or the fifth commutation calculation phase, then the commutation current of the current calculation point marker is obtained; the calculation phase of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the three-phase calculation point voltage; if the calculation phase corresponding to the current calculation point marker is the second non-commutation calculation phase, the fourth non-commutation calculation phase, or the sixth non-commutation calculation phase, the calculation phase of the next calculation point is determined based on the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage. The proposed numerical calculation method for AC / DC harmonics of a three-pulse converter involves discretizing electrical parameters to obtain the calculation point voltages of the three phases. Then, based on the calculation point data and the corresponding calculation point voltages of all three phases, staged harmonic solutions are performed. During the discrete numerical solution of the commutation process, the DC voltage under the background harmonics of the three-phase AC voltage can be naturally considered, resulting in accurate DC voltage harmonic calculation results for the three-pulse converter unit. This harmonic calculation method is simple, fast, and accurate, solving the technical problem of poor accuracy in AC / DC harmonic calculation results due to the difficulty in solving the analytical solution of the differential equation when considering the background harmonics of the three-phase AC voltage in existing three-pulse unit AC / DC harmonic calculation methods.

[0102] In one embodiment of this application, if the converter includes multiple three-pulse converter units, the AC / DC harmonic calculation method of the three-pulse converter further includes: constructing DC voltage waveforms and AC current waveforms for all DC voltages and all AC currents of each three-pulse converter unit, and then adding the AC current waveforms of the DC voltage waveforms of all three-pulse converter units to obtain the corresponding total DC voltage waveform and total AC current waveform; performing frequency domain conversion on the total DC voltage waveform and total AC current waveform using fast Fourier transform to obtain frequency domain voltage data and frequency domain current data in complex form corresponding to each DC voltage and corresponding to each AC current; using the first to N / 2th frequency domain voltage data as the first to N / 2th AC / DC voltage harmonic data of the three-pulse converter unit; and using the first to N / 2th frequency domain current data as the first to N / 2th current harmonic data of the three-pulse converter unit.

[0103] In one embodiment of this application, determining the three-phase calculation point voltage of each calculation point based on the number of calculation points and electrical quantity parameters includes: calculating the three-phase calculation point voltage corresponding to each calculation point based on the value of each calculation point and all positive sequence voltage components, positive sequence voltage component phase angles, negative sequence voltage components and negative sequence voltage component phase angles.

[0104] It should be noted that in calculating the three-phase voltage at each calculation point, based on the specific values ​​at each calculation point, and combined with the positive-sequence voltage components, their phase angles, negative-sequence voltage components, and their phase angles for all calculations, the three-phase voltage value corresponding to each calculation point is precisely calculated using a pre-set formula. This can be understood as follows: first, after determining the specific values ​​at each calculation point, step S1 comprehensively acquires the data for all positive-sequence voltage components, their corresponding phase angles, negative-sequence voltage components, and their corresponding phase angles. Then, according to the principles and rules of power system voltage synthesis, these data are meticulously processed to ultimately obtain the three-phase voltage precisely corresponding to each calculation point.

[0105] For example, based on the value at each calculation point and the positive-sequence voltage component, positive-sequence voltage component phase angle, negative-sequence voltage component, and negative-sequence voltage component phase angle for all calculations, the calculation point voltage is calculated using the calculation point voltage formula to obtain the three-phase calculation point voltage corresponding to each calculation point. The calculation point voltage formula is:

[0106]

[0107]

[0108]

[0109] In the formula, N is the number of calculation points, 1≤k≤N, k is the value of the kth calculation point, n is the nth harmonic of the three-phase AC voltage, and u a (k) represents the voltage at the a-phase calculation point of the k-th calculation point, u b (k) represents the voltage at the b-phase calculation point of the k-th calculation point, u c (k) represents the voltage of phase c at the kth calculation point.

[0110] In one embodiment of this application, determining the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point includes:

[0111] The discrete calculation start point is used as the initial calculation point variable. The value of the calculation point variable is incremented by 1 for each calculation.

[0112] If the variable being calculated is not greater than the number of calculated points, then the variable being calculated is used as the current value of the calculated point; if the variable being calculated is greater than the number of calculated points, then the difference between the variable being calculated and the number of calculated points is used as the current value of the calculated point.

[0113] If the current calculation point mark is greater than the initial calculation point mark, the difference between the current calculation point mark and the initial calculation point mark is used as the previous calculation point mark; if the current calculation point mark is equal to the initial calculation point mark, the number of calculation points is used as the previous calculation point mark.

[0114] It should be noted that the discrete calculation starting point k is determined based on step S2. s and discrete calculation endpoint k e The value has N calculation points. The calculation point variable k is used. loop As a loop variable, the point variable k is calculated at the very beginning. loop Set as the starting point k for discrete computation s The calculation begins in a loop, with the calculation point variable k used for each iteration. loop Increment by 1 until the discrete calculation endpoint k is reached. e In each calculation, the calculation point variable k is used for that calculation. loop The numerical value is calculated from the point variable k according to the pre-defined rules for calculating the marked quantity. loop The value determines the current calculation point marker k and the previous calculation point marker k0. In this embodiment, the initial calculation point marker can be set to 1. The marker calculation rule can be understood as: if k loop Less than or equal to N, k=k loop If k loop Greater than N, k=k loop-N. Let the previous calculation point marker be k0. If k is greater than 1, k0 = k - 1; if k equals 1, k0 = N. The AC / DC harmonic numerical calculation method for this three-pulse converter clarifies the update rule for the calculation point variable (adding 1 for each calculation) and bases it on the calculation point variable k. loo The relationship between the number of calculation points N and the current calculation point marker k ensures an ordered and non-repeating traversal of all points requiring calculation. For example, in a discretized power frequency cycle, a series of discrete calculation points or sampling points need to be calculated. The marker calculation rule ensures that each point is accurately processed, avoiding omissions or duplicate calculations, and guaranteeing the consistency and accuracy of the calculation. In analyzing the voltage and current waveforms in a converter, the waveforms are periodic. By remapping the portion exceeding the number of calculation points into effective markers, a complete analysis of the data within a power frequency cycle can be easily performed, and the previous marker can be used to analyze the waveform's changing trends and correlations.

[0115] It is understandable that the specific steps involved in determining the current calculation point marker, the previous calculation point marker, and the calculation point variables include:

[0116] Initialize the computation point variable: Set the discrete computation starting point k s Set as the calculation point variable k loop The initial value;

[0117] Update the computation point variable: After each computation operation is completed, update the computation point variable k. loop The value increases by 1;

[0118] Determine the current computation point marker: when computation point variable k loop When the value is less than or equal to the number of calculation points N, the calculation point variable k is directly used. loop The value of k is used as the current calculation point marker; when calculating point variable k loop When the value is greater than the number of calculation points N, calculate the calculation point variable k. loop The difference between the current number of calculation points N and the current number of calculation points N is used as the current calculation point label k.

[0119] Determine the previous calculation point marker value: If the value of the current calculation point marker value k is greater than the initial calculation point marker value (here, the initial calculation point marker value can be understood as the first valid marker value under certain initial conditions, which can be specified according to the actual situation, such as the initial calculation point marker value being 1), calculate the difference between the current calculation point marker value k and 1, and use this difference as the previous calculation point marker value k0; if the value of the current calculation point marker value k is equal to 1, use the number of calculation points N as the previous calculation point marker value k0.

[0120] In one embodiment of this application, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the three-phase calculation point voltages, including:

[0121] If the commutation current corresponding to the current calculation point marker is greater than the DC output current, then the calculation stage of the next calculation point is the corresponding second non-commutation calculation stage, fourth non-commutation calculation stage, or sixth non-commutation calculation stage.

[0122] If the commutation current corresponding to the current calculation point marker is not greater than the DC output current, the calculation stage of the next calculation point will still be the corresponding first commutation calculation stage, third commutation calculation stage, or fifth commutation calculation stage.

[0123] If the calculation stage corresponding to the current calculation point mark is the first commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase c, and the calculation point voltages of phase a and phase c corresponding to the current calculation point mark.

[0124] If the calculation stage corresponding to the current calculation point mark is the third commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase b, and the calculation point voltages of phase a and phase b corresponding to the current calculation point mark.

[0125] If the calculation stage corresponding to the current calculation point mark is the fifth commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase b, the equivalent inductance of phase c, and the calculation point voltages of phase b and phase c corresponding to the current calculation point mark.

[0126] It should be noted that, based on whether the calculation stage corresponding to the current calculation point marker is the first, third, or fifth commutation calculation stage, the commutation current of the current calculation point marker is obtained and compared with the DC output current of the electrical quantity parameter. If the commutation current > the DC output current, the next calculation point is the corresponding second, fourth, or sixth non-commutation calculation stage; if the commutation current ≤ the DC output current, the next calculation point remains unchanged, i.e., the corresponding first, third, or fifth commutation calculation stage. In the first commutation calculation stage, the DC voltage corresponding to the current calculation point marker is calculated based on the equivalent inductance of phase a, the equivalent inductance of phase c, and the voltages of phase a and phase c corresponding to the current calculation point marker. In the third commutation calculation stage, the DC voltage corresponding to the current calculation point marker is calculated based on the equivalent inductance of phase a, the equivalent inductance of phase b, and the voltages of phase a and phase b corresponding to the current calculation point marker. In the fifth commutation calculation stage, the DC voltage corresponding to the current calculation point marker is calculated based on the equivalent inductance of phase b, the equivalent inductance of phase c, and the corresponding voltages of phase b and phase c. In this embodiment, detailed parameter calculation rules are formulated for different commutation calculation stages. The DC voltage is calculated based on the corresponding equivalent inductance and calculation point voltage, so that the AC / DC harmonic numerical calculation method of the three-pulse converter can take into account the differences in electrical characteristics of power equipment (such as the converter) at different stages, thereby obtaining a more accurate DC voltage.

[0127] For example, in the first commutation calculation stage, the DC voltage corresponding to the current calculation point is calculated using a pre-set first voltage formula based on the equivalent inductance of phase a, the equivalent inductance of phase c, and the voltages at the current calculation point markings for phase a and phase c. In the third commutation calculation stage, the DC voltage corresponding to the current calculation point markings is calculated using a pre-set second voltage formula based on the equivalent inductance of phase a, the equivalent inductance of phase b, and the voltages at the current calculation point markings for phase a and phase b. In the fifth commutation calculation stage, the DC voltage corresponding to the current calculation point markings is calculated using a pre-set third voltage formula based on the equivalent inductance of phase b, the equivalent inductance of phase c, and the voltages at the current calculation point markings for phase b and phase c. The first voltage formula is:

[0128]

[0129] The second voltage formula is:

[0130]

[0131] The third voltage formula is:

[0132]

[0133] In the formula, u mo (k) represents the DC voltage corresponding to the current calculation point marker k, u a (k) represents the voltage at the a-phase calculation point corresponding to the current calculation point marker k, u b (k) represents the b-phase calculation point voltage corresponding to the current calculation point marker k, u c (k) represents the c-phase calculation point voltage corresponding to the current calculation point marker k, L a For phase a, the inductance is equal to that of phase a, L b For phase b, the equivalent inductance, L c It is the inductance of phase c.

[0134] In one embodiment of this application, if the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined based on the calculation point variables, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage, including:

[0135] When the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the trigger angle judgment data is obtained based on the calculation point variable and the number of calculation points; the first trigger angle threshold, the second trigger angle threshold, and the third trigger angle threshold corresponding to the second non-commutation calculation stage, the fourth non-commutation calculation stage, and the sixth non-commutation calculation stage are calculated respectively based on the b-phase trigger angle, the c-phase trigger angle, and the a-phase trigger angle.

[0136] If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is not less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point is the corresponding third commutation calculation stage, fifth commutation calculation stage, or first commutation calculation stage.

[0137] If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point will still be the corresponding second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage.

[0138] If the calculation stage corresponding to the current calculation point mark is the second non-commutation calculation stage, then the parameter calculation rule is to take the voltage of the a-phase calculation point corresponding to the current calculation point mark as the DC voltage of the current calculation point mark.

[0139] If the calculation stage corresponding to the current calculation point mark is the fourth non-commutation calculation stage, then the parameter calculation rule is to take the b-phase calculation point voltage corresponding to the current calculation point mark as the DC voltage of the current calculation point mark.

[0140] If the calculation stage corresponding to the current calculation point marker is the sixth non-commutation calculation stage, then the parameter calculation rule is to take the c-phase calculation point voltage corresponding to the current calculation point marker as the DC voltage of the current calculation point marker.

[0141] It should be noted that when determining whether the calculation stage corresponding to the previous calculation point marker is the second, fourth, or sixth non-commutation calculation stage, the calculation rules for DC voltage are clearly distinguished according to different stages. This makes the calculation process clearer and easier to understand, facilitating development and maintenance. This calculation method reduces the amount of calculation, improves calculation efficiency, and can meet the needs of applications with high real-time requirements. Specifically, the trigger angle judgment data is obtained first based on the calculation point variables and the number of calculation points. Then, the first trigger angle threshold, second trigger angle threshold, and third trigger angle threshold corresponding to the second, fourth, and sixth non-commutation calculation stages are calculated separately based on the trigger angles of phase b, phase c, and phase a, respectively. Secondly, if the trigger angle judgment data in the calculation stage is not less than the corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold: the calculation stage for the next calculation point is the corresponding third commutation calculation stage, fifth commutation calculation stage, or first commutation calculation stage; if the trigger angle judgment data in the calculation stage is less than the corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold: the calculation stage for the next calculation point is still the corresponding second non-commutation calculation stage, fourth non-commutation calculation stage, or sixth non-commutation calculation stage. Finally, the DC voltage is calculated. In the second non-commutation calculation stage, the voltage u of phase a corresponding to the current calculation point marker k is calculated. a (k) represents the DC voltage u mo (k), i.e., u mo (k)=u a (k); In the fourth non-commutation calculation stage, the voltage u of the b-phase calculation point corresponding to the current calculation point marker k will be... b (k) represents the DC voltage u mo (k), i.e., u mo (k)=u b (k); In the sixth non-commutation calculation stage, the voltage u of the c-phase calculation point corresponding to the current calculation point marker k will be...c (k) represents the DC voltage u mo (k), i.e., u mo (k)=u c (k). Among them, the numerical calculation method for AC and DC harmonics of the three-pulse converter has formulated simple and effective DC voltage calculation rules for different non-commutation calculation stages. That is, the calculation point voltage of the corresponding phase is directly used as the DC voltage, which can quickly and accurately obtain the DC voltage and reduce the calculation complexity and error.

[0142] For example, the trigger angle judgment data is obtained by using the trigger angle judgment formula based on the calculation point variables and the number of calculation points. The trigger angles α3 (phase b), α5 (phase c), and α1 (phase a) are calculated using the first threshold formula, second threshold formula, and third threshold formula, respectively, to obtain the first trigger angle threshold, second trigger angle threshold, and third trigger angle threshold corresponding to the second, fourth, and sixth non-commutation calculation stages, respectively. The trigger angle judgment formula is as follows:

[0143]

[0144] The formula for the first threshold is: The formula for the second threshold is: The third threshold formula is: ;

[0145] In the formula, α is the trigger angle judgment data, α set1 α is the first trigger angle threshold. set2 α is the second trigger angle threshold. set3 α1 is the third trigger angle threshold, α3 is the trigger angle of phase a, α5 is the trigger angle of phase b, and α5 is the trigger angle of phase c.

[0146] In one embodiment of this application, obtaining the commutation current of the current calculation point marker includes:

[0147] The discrete calculation step size is determined based on the power frequency period and the number of calculation points;

[0148] Based on the electrical quantity parameters and the discrete calculation step size, determine the first discrete coefficient, the second discrete coefficient, and the third discrete coefficient;

[0149] Obtain the commutation data of the previous calculation point marker. The commutation data includes the commutation current, phase a commutation voltage, and phase c commutation voltage of the previous calculation point.

[0150] Based on the first discrete coefficient, the second discrete coefficient, the third discrete coefficient, the previous commutation data, the DC output current, and the calculation point voltage of the three phases at the current calculation point, determine the commutation current corresponding to the current calculation point marker.

[0151] It should be noted that in calculating the commutation current at each calculation point, the power frequency period can be divided by the number of calculation points to obtain the discrete calculation step size. Next, based on the electrical quantity parameters and the discrete calculation step size, the first, second, and third discrete coefficients are calculated. Then, the commutation current, the commutation voltage before phase a, and the commutation voltage before phase c are obtained from the previous calculation point (such as the previous calculation point marker). By introducing the previous commutation data, combined with the calculation point voltages of the three phases at the current calculation point and the DC output current, the commutation strategy can be dynamically adjusted to obtain an accurate commutation current. Finally, the previously obtained data, the DC output current, and the calculation point voltages of the three phases at the current calculation point are substituted into the pre-set commutation current formula and commutation current calculation model. Through a series of mathematical operations, the commutation current i corresponding to the current calculation point marker k is finally determined. r (k). In this embodiment, the commutation current formula is: In the formula, i r (k) represents the commutation current of the current calculation point marker k, c1 is the first discrete coefficient, c2 is the second discrete coefficient, c3 is the third discrete coefficient, and I d For DC output current, i r (k0) is the commutation current of the previously calculated point marker k0, u a (k) represents the phase a calculation point voltage of the current calculation point marker k, u c (k) represents the c-phase calculation point voltage of the current calculation point marker k, u a (k0) is the phase a voltage calculated in the previous step, where k0 is the point marker. c (k0) is the c-phase calculation point voltage of the previous calculation point marker k0. The AC / DC harmonic numerical calculation method for this three-pulse converter provides data for determining whether to switch to the next calculation point by calculating the commutation current during the commutation calculation stage, and also provides data for calculating the AC current.

[0152] For example, in determining the discrete calculation step size, based on the given power frequency period T1 and the number of calculation points N, the two are divided, i.e., discrete calculation step size ΔT = T1 / N, to accurately determine the discrete calculation step size; this is to match the harmonic frequency in the AC current calculation and avoid the loss of high-frequency information. In calculating the discrete coefficients, based on the electrical quantity parameters (covering key parameters such as resistance and inductance) and the determined discrete calculation step size, the first, second, and third discrete coefficients are calculated respectively by setting specific mathematical models or formulas. This three-pulse converter AC / DC harmonic numerical calculation method can correct the influence of harmonics on the dynamic characteristics of power equipment by introducing discrete coefficients in the commutation current calculation process. For example, in Fourier series-based harmonic analysis, discrete coefficients are used to adjust the amplitude and phase of each harmonic, making the calculated harmonic data closer to the actual harmonic environment, thereby improving the accuracy of commutation current calculation.

[0153] In one embodiment of this application, determining the first discrete coefficient, the second discrete coefficient, and the third discrete coefficient based on electrical quantity parameters and the discrete calculation step size includes:

[0154] The first discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase c, the equivalent inductance of phase a, and the equivalent inductance of phase c.

[0155] The second discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase a, and the equivalent inductance of phase b.

[0156] The third discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase c, the equivalent resistance of phase b, the equivalent inductance of phase c, and the equivalent inductance of phase b.

[0157] It should be noted that the determination of the discrete coefficients (such as the first, second, and third discrete coefficients) needs to consider the changes in electrical quantity parameters (resistance, inductance, etc.) under harmonic environments. Harmonics cause inductive reactance to change with frequency. By introducing discrete coefficients, the influence of harmonics on the dynamic characteristics of power equipment can be corrected. In this embodiment, the first discrete coefficient is calculated using the first discrete coefficient formula based on the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase c, the equivalent inductance of phase a, and the equivalent inductance of phase c. The second discrete coefficient is calculated using the second discrete coefficient formula based on the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase a, and the equivalent inductance of phase b. The third discrete coefficient is calculated using the third discrete coefficient formula based on the discrete calculation step size, the equivalent resistance of phase c, the equivalent resistance of phase b, the equivalent inductance of phase c, and the equivalent inductance of phase b. The formula for the first discrete coefficient is:

[0158]

[0159] The formula for the second coefficient of dispersion is:

[0160]

[0161] The formula for the third coefficient of dispersion is:

[0162]

[0163] In the formula, ΔT is the step size for discrete calculation; in calculating the first discrete coefficient c1, R1 = R a R2=R c L1=L a L2=L c In calculating the second discrete coefficient c2, R1 = R b R2=R a L1=L b L2=La In calculating the third discrete coefficient c3, R1 = R c R2=R b L1=L c L2=L b .

[0164] In this embodiment, the AC / DC harmonic calculation method for the three-pulse converter can accurately consider DC voltage harmonics under the background of three-phase AC voltage, and has the advantages of high calculation accuracy and high precision.

[0165] Figure 3 This is an equivalent circuit diagram of the phase commutation process from phase C to phase A in the AC / DC harmonic numerical calculation method of the three-pulse converter described in the embodiments of this application.

[0166] In the embodiments of this application, such as Figure 3 As shown, taking the commutation process from phase C to phase A as an example, and taking the commutation current i as an example... r As a state variable, the dynamic equation for the current during commutation is:

[0167]

[0168] For the above differential equation, the discretized solution equation can be obtained:

[0169]

[0170] The following discrete computation equation can be obtained:

[0171]

[0172] Right now

[0173]

[0174] in

[0175]

[0176]

[0177]

[0178] Based on the current loop of phase 1, the dynamic equations during the commutation process can be expressed as follows:

[0179]

[0180] Based on the current loop of phase 2, the dynamic equations during the commutation process can be expressed as follows:

[0181]

[0182] By combining the two equations for the current loop of phase 1 and the current loop of phase 2, we can obtain:

[0183]

[0184]

[0185] If resistance is ignored, the DC current u during commutation can be obtained. MO The voltage expression between them is:

[0186]

[0187] Based on the above derivation process, the data shown in Table 1 is obtained.

[0188] Table 1 shows the division of the six calculation stages of the three-pulsation unit and the calculated DC voltage and AC current.

[0189]

[0190] Example 2:

[0191] Figure 4 This is a schematic diagram of the frame of the AC / DC harmonic numerical calculation device for the three-pulse converter described in the embodiments of this application.

[0192] like Figure 4 As shown in the figure, this application provides an AC / DC harmonic numerical calculation device for a three-pulse converter, including a data acquisition module 10, a first calculation module 20, a second calculation module 30, a voltage calculation module 40, and a harmonic determination module 50;

[0193] The data acquisition module 10 is used to acquire the electrical parameters, power frequency cycle and number of calculation points of the three-pulse converter unit in the converter; and to divide the power frequency cycle into six calculation stages; the six calculation stages include the first commutation calculation stage, the second non-commutation calculation stage, the third commutation calculation stage, the fourth non-commutation calculation stage, the fifth commutation calculation stage and the sixth non-commutation calculation stage, which are calculated by ring cyclic switching.

[0194] The first calculation module 20 is used to determine the three-phase calculation point voltage of each calculation point based on the number of calculation points and electrical quantity parameters; and to determine the discrete calculation start point and discrete calculation end point based on the a-phase firing angle and the number of calculation points of the electrical quantity parameters.

[0195] The second calculation module 30 is used to determine the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point.

[0196] The voltage calculation module 40 is used to take the first commutation calculation stage as the initial calculation stage. If the calculation point variable is not greater than the number of calculation points, it determines the parameter calculation rules and the calculation stage of the next calculation point according to the calculation stage corresponding to the current calculation point mark. The calculation continues until the calculation point variable is greater than the number of calculation points, and the DC voltage corresponding to the number of calculation points is obtained.

[0197] The harmonic determination module 50 is used to process all DC voltages to obtain the AC and DC voltage harmonic data of the three-pulse converter unit;

[0198] If the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the three-phase calculation point voltage.

[0199] If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined based on the calculation point variables, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage.

[0200] It should be noted that the content of the modules in the device of Embodiment 2 has been described in the steps of the method of Embodiment 1, and the content of the AC / DC harmonic numerical calculation device module of the three-pulse converter will not be described again in this embodiment. In this embodiment, the AC / DC harmonic numerical calculation device of the three-pulse converter performs discrete processing on the electrical quantity parameters through the data acquisition module, the first calculation module, the second calculation module, the voltage calculation module, and the harmonic determination module to obtain the calculation point voltage of the three phases. Then, based on the calculation point data and the corresponding calculation point voltage of all three phases, the harmonics are solved in stages. In the discrete numerical solution commutation process, the DC voltage under the background harmonics of the three-phase AC voltage can be naturally calculated, and the accurate DC voltage harmonic calculation result of the three-pulse converter unit can be obtained. This harmonic calculation method is simple, fast, and accurate.

[0201] Example 3:

[0202] Figure 5 This is a schematic diagram of the terminal device described in an embodiment of this application.

[0203] like Figure 5 As shown, this application provides a terminal device, including a processor and a memory;

[0204] Memory is used to store program code and transfer the program code to the processor;

[0205] The processor is used to execute the above-mentioned AC / DC harmonic numerical calculation method for the three-pulse converter according to the instructions in the program code.

[0206] It should be noted that the processor is used to execute the steps in the above-described embodiment of the AC / DC harmonic numerical calculation method for a three-pulse converter according to the instructions in the program code. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above-described system / device embodiments.

[0207] For example, a computer program can be divided into one or more modules / units, one or more of which are stored in memory and executed by a processor to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in a terminal device.

[0208] Terminal devices can be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. Terminal devices may include, but are not limited to, processors and memory. Those skilled in the art will understand that this does not constitute a limitation on the terminal device, which may include more or fewer components than illustrated, or combinations of certain components, or different components. For example, a terminal device may also include input / output devices, network access devices, buses, etc.

[0209] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0210] Memory can be an internal storage unit of a terminal device, such as a hard drive or RAM. Memory can also be an external storage device, such as a plug-in hard drive, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, memory can include both internal and external storage units. Memory is used to store computer programs and other programs and data required by the terminal device. Memory can also be used to temporarily store data that has been output or will be output.

[0211] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0212] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0213] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0214] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0215] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0216] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A numerical calculation method for AC / DC harmonics in a three-pulse converter, characterized in that, Includes the following steps: Obtain the electrical parameters, power frequency cycle, and number of calculation points of the three-pulse converter unit in the converter; and divide the power frequency cycle into six calculation stages; The six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage, which are calculated by a circular cyclic switching. Based on the number of calculation points and the electrical quantity parameters, determine the three-phase calculation point voltage for each calculation point; based on the a-phase firing angle of the electrical quantity parameters and the number of calculation points, determine the discrete calculation start point and discrete calculation end point; Based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point, determine the current calculation point marker, the previous calculation point marker, and the calculation point variable; Taking the first commutation calculation stage as the initial calculation stage, if the calculation point variable is not greater than the number of calculation points, the parameter calculation rules and the calculation stage for cyclically calculating the next calculation point are determined according to the calculation stage corresponding to the current calculation point mark. The process continues until the variable at the calculation point is greater than the number of calculation points, at which point the DC voltage corresponding to the number of calculation points is obtained. All the DC voltages are processed to obtain the AC and DC voltage harmonic data of the three-pulse converter unit; Wherein, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained; the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameter; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameter and the three-phase calculation point voltage. If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage.

2. The method for numerically calculating AC / DC harmonics in a three-pulse converter according to claim 1, characterized in that, The electrical quantity parameters include a three-phase AC voltage containing multiple positive-sequence voltage components, positive-sequence voltage component phase angles, negative-sequence voltage components, and negative-sequence voltage component phase angles. Determining the calculation point voltage of the three phases at each calculation point based on the number of calculation points and the electrical quantity parameters includes: calculating the calculation point voltage of the three phases corresponding to each calculation point based on the value of each calculation point and all occurrences of the positive-sequence voltage components, positive-sequence voltage component phase angles, negative-sequence voltage components, and negative-sequence voltage component phase angles.

3. The method for numerically calculating AC / DC harmonics in a three-pulse converter according to claim 1, characterized in that, Based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point, the current calculation point marker, the previous calculation point marker, and the calculation point variables are determined as follows: Using the discrete calculation starting point as the initial calculation point variable, the value of the calculation point variable is incremented by 1 for each calculation; If the calculated point variable is not greater than the number of calculated points, then the calculated point variable is used as the current calculated point marker; if the calculated point variable is greater than the number of calculated points, then the difference between the calculated point variable and the number of calculated points is used as the current calculated point marker. If the current calculation point marker quantity is greater than the initial calculation point marker quantity, then the difference between the current calculation point marker quantity and the initial calculation point marker quantity is used as the previous calculation point marker quantity; if the current calculation point marker quantity is equal to the initial calculation point marker quantity, then the calculation point quantity is used as the previous calculation point marker quantity.

4. The method for numerically calculating AC / DC harmonics of a three-pulse converter according to claim 1, characterized in that, The electrical quantity parameters include the equivalent resistance of phase a, the equivalent inductance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase b, the equivalent resistance of phase c, and the equivalent inductance of phase c; the calculation point voltages of the three phases include the calculation point voltages of phase a, phase b, and phase c; if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameters; Furthermore, the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameters and the three-phase calculation point voltage, including: If the commutation current corresponding to the current calculation point marker is greater than the DC output current, then the calculation stage of the next calculation point is the corresponding second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage. If the commutation current corresponding to the current calculation point marker is not greater than the DC output current, then the calculation stage of the next calculation point is still the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage. If the calculation stage corresponding to the current calculation point mark is the first commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase c, and the calculation point voltage of phase a and phase c corresponding to the current calculation point mark. If the calculation stage corresponding to the current calculation point mark is the third commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point mark based on the equivalent inductance of phase a, the equivalent inductance of phase b, and the calculation point voltages of phase a and phase b corresponding to the current calculation point mark. If the calculation stage corresponding to the current calculation point marker is the fifth commutation calculation stage, then the parameter calculation rule is to calculate the DC voltage corresponding to the current calculation point marker based on the b-phase equivalent inductance, the c-phase equivalent inductance, and the b-phase calculation point voltage and the c-phase calculation point voltage corresponding to the current calculation point marker.

5. The method for numerically calculating AC / DC harmonics in a three-pulse converter according to claim 1, characterized in that, The electrical quantity parameters include the phase b firing angle and the phase c firing angle, and the three-phase calculation point voltages include the phase a calculation point voltage, the phase b calculation point voltage, and the phase c calculation point voltage; if the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; Furthermore, the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage, including: When the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the trigger angle judgment data is obtained based on the calculation point variable and the number of calculation points; the first trigger angle threshold, the second trigger angle threshold, and the third trigger angle threshold corresponding to the second non-commutation calculation stage, the fourth non-commutation calculation stage, and the sixth non-commutation calculation stage are calculated based on the b-phase trigger angle, the c-phase trigger angle, and the a-phase trigger angle, respectively. If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is not less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point is the corresponding third commutation calculation stage, fifth commutation calculation stage, or first commutation calculation stage. If the trigger angle judgment data of the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage is less than its corresponding first trigger angle threshold, second trigger angle threshold, or third trigger angle threshold, then the calculation stage of the next calculation point is still the corresponding second non-commutation calculation stage, fourth non-commutation calculation stage, or sixth non-commutation calculation stage. If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, then the parameter calculation rule is to take the voltage of the a-phase calculation point corresponding to the current calculation point marker as the DC voltage of the current calculation point marker. If the calculation stage corresponding to the current calculation point marker is the fourth non-commutation calculation stage, then the parameter calculation rule is to take the b-phase calculation point voltage corresponding to the current calculation point marker as the DC voltage of the current calculation point marker. If the calculation stage corresponding to the current calculation point marker is the sixth non-commutation calculation stage, then the parameter calculation rule is to use the c-phase calculation point voltage corresponding to the current calculation point marker as the DC voltage of the current calculation point marker.

6. The method for numerically calculating AC / DC harmonics in a three-pulse converter according to claim 1, characterized in that, Obtaining the commutation current of the current calculation point marker includes: The discrete calculation step size is determined based on the power frequency period and the number of calculation points; Based on the electrical quantity parameters and the discrete calculation step size, the first discrete coefficient, the second discrete coefficient, and the third discrete coefficient are determined. Obtain the commutation data of the previous calculation point marker, the commutation data including the commutation current, phase a commutation voltage and phase c commutation voltage of the previous calculation point; Based on the first discrete coefficient, the second discrete coefficient, the third discrete coefficient, the previous commutation data, the DC output current, and the calculation point voltage of the three phases at the current calculation point, determine the commutation current corresponding to the current calculation point marker.

7. The method for numerically calculating AC / DC harmonics in a three-pulse converter according to claim 6, characterized in that, The electrical quantity parameters include the equivalent resistance of phase a, the equivalent inductance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase b, the equivalent resistance of phase c, and the equivalent inductance of phase c. Based on the electrical quantity parameters and the discrete calculation step size, the first discrete coefficient, the second discrete coefficient, and the third discrete coefficient are determined as follows: The first discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase c, the equivalent inductance of phase a, and the equivalent inductance of phase c. The second discrete coefficient is obtained by calculating the discrete calculation step size, the equivalent resistance of phase a, the equivalent resistance of phase b, the equivalent inductance of phase a, and the equivalent inductance of phase b. The third discrete coefficient is obtained by calculating the discrete calculation step size, the c-phase equivalent resistor, the b-phase equivalent resistor, the c-phase equivalent inductor, and the b-phase equivalent inductor.

8. The method for numerically calculating AC / DC harmonics of a three-pulse converter according to any one of claims 1-7, characterized in that, If the number of calculation points is denoted as N, the voltage harmonic data of the AC and DC circuits of the three-pulse converter unit are obtained by processing all the DC voltages, including: All the DC voltages are used to form a DC voltage waveform. The DC voltage waveform is then converted to the frequency domain using a fast Fourier transform to obtain the frequency domain voltage data corresponding to each DC voltage in complex form. The first to the N / 2nd frequency domain voltage data are used as the first to the N / 2nd AC / DC voltage harmonic data of the three-pulse converter unit.

9. A numerical calculation device for AC / DC harmonics of a three-pulse converter, characterized in that, include: Data acquisition module, first calculation module, second calculation module, voltage calculation module, and harmonic determination module; The data acquisition module is used to acquire the electrical parameters, power frequency cycle, and number of calculation points of the three-pulse converter unit in the converter; and to divide the power frequency cycle into six calculation stages; The six calculation stages include a first commutation calculation stage, a second non-commutation calculation stage, a third commutation calculation stage, a fourth non-commutation calculation stage, a fifth commutation calculation stage, and a sixth non-commutation calculation stage, which are calculated by a circular cyclic switching. The first calculation module is used to determine the three-phase calculation point voltage of each calculation point based on the number of calculation points and the electrical quantity parameters; and to determine the discrete calculation start point and discrete calculation end point based on the a-phase firing angle of the electrical quantity parameters and the number of calculation points. The second calculation module is used to determine the current calculation point marker, the previous calculation point marker, and the calculation point variable based on the number of calculation points, the discrete calculation start point, and the discrete calculation end point. The voltage calculation module is used to take the first commutation calculation stage as the initial calculation stage, and if the calculation point variable is not greater than the number of calculation points, determine the parameter calculation rules and the calculation stage for cyclically calculating the next calculation point according to the calculation stage corresponding to the current calculation point mark. The process continues until the variable at the calculation point is greater than the number of calculation points, at which point the DC voltage corresponding to the number of calculation points is obtained. The harmonic determination module is used to process all the DC voltages to obtain the AC and DC voltage harmonic data of the three-pulse converter unit. Wherein, if the calculation stage corresponding to the current calculation point marker is the first commutation calculation stage, the third commutation calculation stage, or the fifth commutation calculation stage, then the commutation current of the current calculation point marker is obtained, and the calculation stage of the next calculation point is determined by comparing the commutation current with the DC output current of the electrical quantity parameter; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the electrical quantity parameter and the three-phase calculation point voltage. If the calculation stage corresponding to the current calculation point marker is the second non-commutation calculation stage, the fourth non-commutation calculation stage, or the sixth non-commutation calculation stage, the calculation stage of the next calculation point is determined according to the calculation point variable, the number of calculation points, and the electrical quantity parameters; and the parameter calculation rule is to determine the DC voltage corresponding to the current calculation point marker based on the three-phase calculation point voltage.

10. A terminal device, characterized in that, Including the processor and memory; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the AC / DC harmonic numerical calculation method for a three-pulse converter as described in any one of claims 1-8, according to the instructions in the program code.

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