Converter split-phase control method and system

Abstract

The embodiment of the invention discloses a converter split-phase control method and system. The method comprises the following steps: acquiring three-phase current measurement values and filter inductance values of a converter side and a grid side at the current moment; determining weighted values of current of the converter side and the grid side according to the filter inductance values of the converter side and the grid side at the current moment; obtaining a three-phase weighted average current measurement value at the current moment by using the weighted values of the current at the converter side and the grid side and the three-phase current measurement values at the converter side and the grid side at the current moment; inputting the measured value of the three-phase weighted average current at the current moment into a linear expansion state observer, and outputting a predicted value of the three-phase weighted average current at the next moment in combination with a recursive least square method; substituting the three-phase weighted average current predicted value at the next moment into the cost function to obtain an optimal voltage vector corresponding to the minimum value of the cost function; and controlling the converter according to the optimal voltage vector. Through the method, the control steady-state performance of the converter can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to a converter phase-splitting control method and system. Background Art

[0002] In recent years, with the rapid development of renewable energy such as wind power generation, distributed photovoltaics, and DC loads such as electric vehicle charging piles, the converter, as the core equipment of AC / DC hybrid power supply systems such as new energy grid connection and flexible interconnection system, has put forward higher requirements on the response speed, control accuracy, and output current harmonics of its control system. As the structure of the converter becomes more complex, traditional control strategies are difficult to apply. Some new control strategies have been introduced into device control, such as finite set model predictive control, but this control depends on the accuracy of the prediction model. In the actual operation of the grid-connected converter, due to the aging of the device components and the influence of the external environment, the parameters usually change over time, resulting in inaccurate models, making it difficult for the control system to obtain optimal performance in practical applications.

[0003] In order to solve the problem of model predictive control parameter mismatch, a model-free control method has been proposed in recent years, and some new control strategies have been spawned, but there are still problems such as the need for more calculation parameters and high model calculation complexity. Summary of the invention

[0004] Based on this, it is necessary to propose a converter phase control method and system to address the above problems.

[0005] First aspect

[0006] A phase-splitting control method for a converter, the method comprising:

[0007] Obtain the three-phase current measurement value on the converter side, the filter inductance value on the converter side, the three-phase current measurement value on the grid side, and the filter inductance value on the grid side at the current moment;

[0008] Determine the weighted value of the current on the converter side and the weighted value of the current on the grid side according to the filter inductance value on the converter side and the filter inductance value on the grid side at the current moment;

[0009] Obtaining a three-phase weighted average current measurement value at the current moment by using the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value at the converter side at the current moment, and the three-phase current measurement value at the grid side;

[0010] The three-phase weighted average current measurement value at the current moment is input into a linear extended state observer, and combined with a recursive least squares method, a three-phase weighted average current prediction value at the next moment is output;

[0011] Substituting the predicted value of the three-phase weighted average current at the next moment into the cost function to obtain the optimal voltage vector corresponding to the minimum value of the cost function;

[0012] The converter is controlled according to the optimal voltage vector.

[0013] Preferably, determining the weighted value of the converter side current and the weighted value of the grid side current according to the filter inductance value of the converter side and the filter inductance value of the grid side at the current moment specifically includes:

[0014] α=L1 / (L1+L2)

[0015] β=L2 / (L1+L2)

[0016] In the formula, α represents the weighted value of the current on the converter side, β represents the weighted value of the current on the grid side, L1 represents the filter inductance value on the converter side at the current moment, and L2 represents the filter inductance value on the grid side at the current moment.

[0017] Preferably, the method of obtaining the three-phase weighted average current measurement value at the current moment by using the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value at the converter side at the current moment, and the three-phase current measurement value at the grid side specifically includes:

[0018] i wa (k) = αi g1a +βi ga

[0019] In the formula, i wa (k) represents the weighted average current measurement value of phase a at the current time k, i g1a represents the measured value of phase a current on the converter side at the current moment k, i ga Indicates the measured value of phase a current on the grid side at time k;

[0020] i wb (k) = αi g1b +βi gb

[0021] In the formula, i wb (k) represents the weighted average current measurement value of phase b at the current time k, i g1b represents the measured value of the current of phase b on the converter side at the current moment k, i gb Indicates the measured value of the phase b current on the grid side at the current time k;

[0022] i wc (k) = αi g1c +βi gc

[0023] In the formula, iwc (k) represents the weighted average current measurement value of phase c at the current time k, i g1c represents the measured value of phase c current on the converter side at the current moment k, i gc Indicates the measured value of the phase c current on the grid side at the current time k.

[0024] Preferably, the three-phase weighted average current measurement value at the current moment is input into a linear extended state observer, and combined with a recursive least squares method, a three-phase weighted average current prediction value at the next moment is output, specifically including:

[0025] The three-phase weighted average current measurement value at the current moment is input into the linear extended state observer to obtain the three-phase current disturbance, which is:

[0026]

[0027] Where e(k) represents the error between the estimated value of the weighted average current of phase a at time k and the measured value of the weighted average current of phase a. represents the estimated value of the weighted average current of phase a at the current time k, i wa (k) represents the weighted average current measurement value of phase a at the current time k, Indicates the estimated value of the weighted average current of phase a at the next moment k+1, T s represents the control cycle, represents the current disturbance of phase a at the current moment k, represents the gain coefficient of the linear extended state observer, S a Indicates the conduction state of the a-phase bridge arm IGBT, U dc (k) represents the DC voltage of the converter at the current time k, l 01 =2T s ω0,l 02 =T s ω0 2 , ω0 represents the natural frequency, represents the current disturbance of phase a at the next moment k+1, G(z) represents the transfer function of phase a current in the z domain, z represents the Lagrangian operator in the z domain, i wa (z) is the weighted average current measurement value of phase a in the z domain, is the estimated value of the weighted average current of phase a in the z domain; the current disturbance of phase b and the current disturbance of phase c are calculated according to the above steps;

[0028] Combined with the recursive least squares method, the predicted value of the three-phase weighted average current at the next moment is output, which is:

[0029]

[0030] In the formula, i wa (k+1) indicates the predicted value of the weighted average current of phase a at the next moment k+1. Indicates the transposition of the historical data of the sampled input and output at the next moment k+1, Indicates the gain coefficient vector that needs to be estimated at the current time k, Indicates the historical data of sampled input and output at the current time k, i wa (k-1) represents the weighted average current measurement value of phase a at the previous moment k-1, u dc (k-1) represents the DC voltage of the converter at the previous moment k-1, u dc (k-2) represents the DC voltage of the converter at the previous moment k-2, θ start (k) represents the initial value of the gain coefficient vector at the current moment k, represents the gain coefficient vector that needs to be estimated at the previous moment k-1, γ(k) represents the parameter update matrix at the current moment k, e(k) represents the error between the actual system output and the estimated output at the current moment k, y(k) represents the actual system output value at the current moment k, represents the transpose of the historical data of the sampled input and output when the current moment is moment k, P(k-1) represents the covariance matrix of the parameter estimation vector when the previous moment is moment k-1, λ represents the forgetting factor, and P(k) represents the covariance matrix of the parameter estimation vector when the current moment is moment k; the weighted average current prediction value of phase b and the weighted average current prediction value of phase c at the next moment are calculated according to the above steps.

[0031] Preferably, the cost function is specifically:

[0032] g=λ1|i wa * -i wa (k+1)|+λ2|i wb * -i wb (k+1)|+λ3|i wc * -i wc (k+1)|

[0033] In the formula, g represents the cost function, λ1 represents the weight of phase a, λ2 represents the weight of phase b, λ3 represents the weight of phase c, and i wa (k+1) represents the predicted value of the weighted average current of phase a at the next moment, i wb (k+1) represents the predicted value of the weighted average current of phase b at the next moment, i wc(k+1) represents the predicted value of the weighted average current of phase c at the next moment, i wa * indicates the reference value required to be output by phase a, i wb * indicates the reference value required to be output by phase b, i wc *Indicates the reference value required for phase C output.

[0034] Second aspect

[0035] A converter phase-splitting control system comprises: a first current measuring device, a second current measuring device, a DC voltage measuring device, a controller and a converter.

[0036] Preferably, the DC voltage measuring device is electrically connected to the controller and is used to obtain the DC voltage on the DC side of the converter.

[0037] Preferably, the first current measuring device is used to measure the three-phase AC current output by the converter, and the second current measuring device is used to measure the three-phase AC current filtered by the filter.

[0038] Preferably, the controller is electrically connected to the first current measuring device, the second current measuring device and the DC voltage measuring device, and is used to obtain the DC voltage of the converter, the three-phase AC current output by the converter and the three-phase AC current filtered by the filter.

[0039] Preferably, the controller includes a historical data analysis module, a control strategy analysis module, an alarm record analysis module and a data import and export module.

[0040] The embodiments of the present invention have the following beneficial effects:

[0041] The inverter phase control method of the present invention requires fewer calculation parameters and has low calculation complexity, and can effectively solve the problem of parameter mismatch in the inverter control system and improve the control steady-state performance of the inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] in:

[0044] Figure 1 is a flow chart of a phase-splitting control method for a converter in one embodiment;

[0045] Figure 2is a schematic diagram of a typical three-phase full-bridge converter structure in an embodiment;

[0046] Figure 3 is a time domain signal diagram in one embodiment;

[0047] Figure 4 FIG. 4 is a structural block diagram of a phase-splitting control system of a converter in one embodiment. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In order to solve the problem of model predictive control parameter mismatch, a model-free control method has been proposed in recent years, and some new control strategies have been spawned, but there are still problems such as requiring more calculation parameters and high model calculation complexity. Therefore, it is urgent to invent a new converter control method that requires fewer calculation parameters and lowers the calculation complexity, and effectively solves the problem of parameter mismatch in the converter control system and improves the control steady-state performance of the converter.

[0050] Figure 1 FIG. 1 is a flow chart of a method for controlling a phase-splitting converter in one embodiment. Figure 1 As shown, the method specifically includes S1100 to S1600:

[0051] S1100, obtaining the three-phase current measurement values ​​on the converter side, the filter inductance value on the converter side, the three-phase current measurement values ​​on the grid side, and the filter inductance value on the grid side at the current moment.

[0052] Figure 2 FIG. 1 is a schematic diagram of a typical three-phase full-bridge converter structure in an embodiment.

[0053] Exemplarily, the three-phase current i at both sides of the LCL filter device at the current moment is obtained by the converter control system. g1 (k), i g (k).

[0054] S1200: Determine a weighted value of the converter-side current and a weighted value of the grid-side current according to a current filter inductance value of the converter-side and a current filter inductance value of the grid-side.

[0055] In some examples, determining a weighted value of the converter side current and a weighted value of the grid side current according to a filter inductance value of the converter side and a filter inductance value of the grid side at a current moment specifically includes:

[0056] α=L1 / (L1+L2)

[0057] β=L2 / (L1+L2)

[0058] In the formula, α represents the weighted value of the current on the converter side, β represents the weighted value of the current on the grid side, L1 represents the filter inductance value on the converter side at the current moment, and L2 represents the filter inductance value on the grid side at the current moment.

[0059] S1300, using the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value of the converter side at the current moment, and the three-phase current measurement value of the grid side, obtain the three-phase weighted average current measurement value at the current moment.

[0060] In some examples, the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value of the converter side at the current moment, and the three-phase current measurement value of the grid side are used to obtain the three-phase weighted average current measurement value at the current moment, specifically including:

[0061] i w =[i wa i wb i wc ] T is the three-phase weighted average current measurement value, i g1 =[i g1a i g1b i g1c ] T is the measured current value on the converter side; i g =[i ga i gb i gc ] T is the measured value of grid-side current;

[0062] i wa (k) = αi g1a +βi ga

[0063] In the formula, i wa (k) represents the weighted average current measurement value of phase a at the current time k, i g1a represents the measured value of phase a current on the converter side at the current moment k, i ga Indicates the measured value of phase a current on the grid side at time k;

[0064] i wb (k) = αi g1b +βi gb

[0065] In the formula, i wb(k) represents the weighted average current measurement value of phase b at the current time k, i g1b represents the measured value of the current of phase b on the converter side at the current moment k, i gb Indicates the measured value of the phase b current on the grid side at the current time k;

[0066] i wc (k) = αi g1c +βi gc

[0067] In the formula, i wc (k) represents the weighted average current measurement value of phase c at the current time k, i g1c represents the measured value of phase c current on the converter side at the current moment k, i gc Indicates the measured value of the phase c current on the grid side at the current time k.

[0068] S1400: Input the three-phase weighted average current measurement value at the current moment into the linear extended state observer, and combine the recursive least squares method to output the three-phase weighted average current prediction value at the next moment.

[0069] In some examples, the three-phase weighted average current measurement value at the current moment is input into the linear extended state observer, and combined with the recursive least squares method, the three-phase weighted average current prediction value at the next moment is output, specifically including:

[0070] The three-phase weighted average current measurement value at the current moment is input into the linear extended state observer to obtain the three-phase current disturbance. Taking phase a as an example, the specific method is as follows: The calculation model predicts the estimated value of the disturbance. Taking phase a as an example, the calculation formula is as follows:

[0071]

[0072] In the formula, e(k) represents the error between the estimated value of the weighted average current of phase a at the current time k and the measured value of the weighted average current of phase a, and its initial value is zero. represents the estimated value of the weighted average current of phase a at the current time k, i wa (k) represents the weighted average current measurement value of phase a at the current time k, Indicates the estimated value of the weighted average current of phase a at the next moment k+1, T s represents the control cycle, represents the current disturbance of phase a at the current moment k, represents the gain coefficient of the linear extended state observer, S a Indicates the conduction state of the a-phase bridge arm IGBT, S a =1 means the upper bridge arm is turned on and the lower bridge arm is turned off, S a=0 means the lower bridge arm is turned on and the upper bridge arm is turned off.

[0073] U dc (k) represents the DC voltage of the converter at the current time k, l 01 =2T s ω0,l 02 =T s ω0 2 , ω0 represents the natural frequency, represents the current disturbance of phase a at the next moment k+1, G(z) represents the transfer function of phase a current in the z domain, z represents the Lagrangian operator in the z domain, i wa (z) is the weighted average current measurement value of phase a in the z domain, is the estimated value of the weighted average current of phase a in the z domain; the current disturbance of phase b and the current disturbance of phase c are calculated according to the above steps;

[0074] Among them, z 1,2 =1-0.5T s ω0, further solve for l 01 =2T s ω0,l 02 =T s ω0 2 , The initial moment is zero. Solve for the value on the ω0 Bode plot that describes the stability of the control system. Further solve for the error and disturbance. (The disturbance has an estimate, the measurement also has an estimate, and the error is zero at the beginning.) Through the unit circle, solve for z and set the expression to zero.

[0075] The calculation logic of the current disturbance is as follows:

[0076] The current at the next moment is updated using the following formula to obtain the error between the estimated value and the measured value. The calculation expression is as follows:

[0077]

[0078] in, It needs to be obtained through the following formula, and the calculation expression is as follows:

[0079]

[0080] pass Find the extreme points of the function, that is, the solutions with zero denominator, z 1,2 =1-0.5T s ω0, the solution is inside the unit circle, indicating that the model is stable, so we can take any number z in the unit circle to find ω0 and then determine l 01 , l 02 , and then through Combined with the recursive least squares method, the three-phase weighted average current prediction value at the next moment is output. Specifically, the current prediction value i under the eight voltage vectors of the converter on and off at time k+1 is calculated by traversal method. w (k+1), the calculation method is as follows: (Take phase a as an example.)

[0081]

[0082] In the formula, i wa (k+1) indicates the predicted value of the weighted average current of phase a at the next moment k+1. Indicates the transposition of the historical data of the sampled input and output at the next moment k+1, Indicates the gain coefficient vector that needs to be estimated at the current time k, Indicates the historical data of sampled input and output at the current time k, i wa (k-1) represents the weighted average current measurement value of phase a at the previous moment k-1, u dc (k-1) represents the DC voltage of the converter at the previous moment k-1, u dc (k-2) represents the DC voltage of the converter at the previous moment k-2, θ start (k) represents the initial value of the gain coefficient vector at the current moment k, represents the gain coefficient vector that needs to be estimated at the previous moment k-1, γ(k) represents the parameter update matrix at the current moment k, e(k) represents the error between the actual system output and the estimated output at the current moment k, y(k) represents the actual system output value at the current moment k, represents the transpose of the historical data of the sampled input and output at the current moment k, P(k-1) represents the parameter estimation vector covariance matrix at the previous moment k-1, λ represents the forgetting factor, and P(k) represents the parameter estimation vector covariance matrix at the current moment k; according to the above steps, the predicted value of the b-phase weighted average current and the predicted value of the c-phase weighted average current at the next moment are calculated. Then calculate i w (k+1).

[0083] The state of the converter conduction is shown in Table 1:

[0084] Table 1 The state of the converter conduction

[0085]

[0086] S1500, substituting the predicted value of the three-phase weighted average current at the next moment into the cost function to obtain the optimal voltage vector corresponding to the minimum value of the cost function.

[0087] Substitute the 8 possible current prediction values ​​at time k+1 into the following formula to calculate the cost function value g x , select the minimum cost function g min The corresponding optimal voltage vector should be used as the output of the control system and act on the device at time k+1.

[0088] In some examples, the cost function is:

[0089] g=λ1|i wa * -i wa (k+1)|+λ2|i wb * -i wb (k+1)|

[0090] +λ3|i wc * -i wc (k+1)|

[0091] In the formula, g represents the cost function, λ1 represents the weight of phase a, λ2 represents the weight of phase b, λ3 represents the weight of phase c, and i wa (k+1) represents the predicted value of the weighted average current of phase a at the next moment, i wb (k+1) represents the predicted value of the weighted average current of phase b at the next moment, i wc (k+1) represents the predicted value of the weighted average current of phase c at the next moment, i wa * indicates the reference value required to be output by phase a, i wb * indicates the reference value required to be output by phase b, i wc *Indicates the reference value required for phase C output.

[0092] S1600: Control the converter according to the optimal voltage vector.

[0093] Figure 3 It is a time domain signal diagram in an embodiment. Through the total harmonic distortion (THD) of the control method of this embodiment, the output current fundamental frequency amplitude is 29.95A, and the harmonic distortion rate is 0.45%, which effectively suppresses the high-frequency components existing in traditional MPCC control, and the steady-state performance is better.

[0094] The inverter phase control method of this embodiment requires fewer calculation parameters and has low calculation complexity, and can effectively solve the problem of parameter mismatch in the inverter control system and improve the control steady-state performance of the inverter.

[0095] Figure 4FIG. 1 is a structural block diagram of a phase-splitting control system of a converter in one embodiment. Figure 4 As shown, the system includes: a first current measuring device (current measuring device 1 in the figure), a second current measuring device (current measuring device 2 in the figure), a DC voltage measuring device, a controller and a converter body.

[0096] In some examples, a DC voltage measuring device is electrically connected to the controller for obtaining a DC voltage on a DC side of the converter.

[0097] In some examples, the first current measuring device is used to measure the three-phase AC current output by the converter, and the second current measuring device is used to measure the three-phase AC current filtered by the filter.

[0098] In some examples, the controller is electrically connected to the first current measuring device, the second current measuring device, and the DC voltage measuring device to obtain the DC voltage of the converter, the three-phase AC current output by the converter, and the three-phase AC current filtered by the filter.

[0099] In some examples, the controller includes a historical data analysis module, a control strategy analysis module, an alarm record analysis module, and a data import and export module.

[0100] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0101] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A phase-splitting control method for a converter, characterized in that: The method comprises: Obtain the three-phase current measurement value on the converter side, the filter inductance value on the converter side, the three-phase current measurement value on the grid side, and the filter inductance value on the grid side at the current moment; Determine the weighted value of the current on the converter side and the weighted value of the current on the grid side according to the filter inductance value on the converter side and the filter inductance value on the grid side at the current moment; Obtaining a three-phase weighted average current measurement value at the current moment by using the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value at the converter side at the current moment, and the three-phase current measurement value at the grid side; The three-phase weighted average current measurement value at the current moment is input into a linear extended state observer, and combined with a recursive least squares method, a three-phase weighted average current prediction value at the next moment is output; Substituting the predicted value of the three-phase weighted average current at the next moment into the cost function to obtain the optimal voltage vector corresponding to the minimum value of the cost function; The converter is controlled according to the optimal voltage vector.

2. The converter phase control method according to claim 1, characterized in that: The step of determining the weighted value of the converter side current and the weighted value of the grid side current according to the filter inductance value of the converter side and the filter inductance value of the grid side at the current moment specifically includes: α=L1 / (L1+L2) β=L2 / (L1+L2) In the formula, α represents the weighted value of the current on the converter side, β represents the weighted value of the current on the grid side, L1 represents the filter inductance value on the converter side at the current moment, and L2 represents the filter inductance value on the grid side at the current moment.

3. The converter phase control method according to claim 1, characterized in that: The method of obtaining the three-phase weighted average current measurement value at the current moment by using the weighted value of the converter side current, the weighted value of the grid side current, the three-phase current measurement value at the converter side at the current moment, and the three-phase current measurement value at the grid side, specifically includes: i wa (k)=αi g1a +βi ga In the formula, i wa (k) represents the weighted average current measurement value of phase a at the current time k, i g1a represents the measured value of phase a current on the converter side at the current moment k, i ga Indicates the measured value of phase a current on the grid side at time k; i wb (k)=αi g1b +βi gb In the formula, i wb (k) represents the weighted average current measurement value of phase b at the current time k, i g1b represents the measured value of the b-phase current on the converter side at the current moment k, i gb Indicates the measured value of the phase b current on the grid side at the current time k; i wc (k)=αi g1c +βi gc In the formula, i wc (k) represents the weighted average current measurement value of phase c at the current time k, i g1c represents the measured value of phase c current on the converter side at the current moment k, i gc Indicates the measured value of the phase c current on the grid side at the current time k.

4. The converter phase control method according to claim 1, characterized in that: The three-phase weighted average current measurement value at the current moment is input into the linear extended state observer, and combined with the recursive least squares method, the three-phase weighted average current prediction value at the next moment is output, specifically including: The three-phase weighted average current measurement value at the current moment is input into the linear extended state observer to obtain the three-phase current disturbance, which is: Where e(k) represents the error between the estimated value of the weighted average current of phase a at time k and the measured value of the weighted average current of phase a. represents the estimated value of the weighted average current of phase a at the current time k, i wa (k) represents the weighted average current measurement value of phase a at the current time k, Indicates the estimated value of the weighted average current of phase a at the next moment k+1, T s represents the control cycle, represents the current disturbance of phase a at the current moment k, represents the gain coefficient of the linear extended state observer, S a Indicates the conduction state of the a-phase bridge arm IGBT, U dc (k) represents the DC voltage of the converter at the current time k, l 01 =2T s ω0,l 02 =T s ω0 2 , ω0 represents the natural frequency, represents the current disturbance of phase a at the next moment k+1, G(z) represents the transfer function of phase a current in the z domain, z represents the Lagrangian operator in the z domain, i wa (z) is the weighted average current measurement value of phase a in the z domain, is the estimated value of the weighted average current of phase a in the z domain; the current disturbance of phase b and the current disturbance of phase c are calculated according to the above steps; Combined with the recursive least squares method, the predicted value of the three-phase weighted average current at the next moment is output, which is: In the formula, i wa (k+1) indicates the predicted value of the weighted average current of phase a at the next moment k+1. Indicates the transposition of the historical data of the sampled input and output at the next moment k+1, Indicates the gain coefficient vector that needs to be estimated at the current time k, Indicates the historical data of sampled input and output at the current time k, i wa (k-1) represents the weighted average current measurement value of phase a at the previous moment k-1, u dc (k-1) represents the DC voltage of the converter at the previous moment k-1, u dc (k-2) represents the DC voltage of the converter at the previous moment k-2, θ start (k) represents the initial value of the gain coefficient vector at the current moment k, represents the gain coefficient vector that needs to be estimated at the previous moment k-1, γ(k) represents the parameter update matrix at the current moment k, e(k) represents the error between the actual system output and the estimated output at the current moment k, y(k) represents the actual system output value at the current moment k, represents the transpose of the historical data of the sampled input and output when the current moment is moment k, P(k-1) represents the covariance matrix of the parameter estimation vector when the previous moment is moment k-1, λ represents the forgetting factor, and P(k) represents the covariance matrix of the parameter estimation vector when the current moment is moment k; the weighted average current prediction value of phase b and the weighted average current prediction value of phase c at the next moment are calculated according to the above steps.

5. The converter phase control method according to claim 1, characterized in that: The cost function is specifically: g=λ1|i wa * -i wa (k+1)|+λ2|i wb * -i wb (k+1)|+λ3|i wc * -i wc (k+1)| In the formula, g represents the cost function, λ1 represents the weight of phase a, λ2 represents the weight of phase b, λ3 represents the weight of phase c, and i wa (k+1) represents the predicted value of the weighted average current of phase a at the next moment, i wb (k+1) represents the predicted value of the weighted average current of phase b at the next moment, i wc (k+1) represents the predicted value of the weighted average current of phase c at the next moment, i wa * indicates the reference value required to be output by phase a, i wb * indicates the reference value required to be output by phase b, i wc *Indicates the reference value required for phase C output.

6. A converter phase control system, characterized in that: The system comprises: a first current measuring device, a second current measuring device, a direct current voltage measuring device, a controller and a converter.

7. The converter phase control system according to claim 6, characterized in that: The DC voltage measuring device is electrically connected to the controller and is used to obtain the DC voltage at the DC side of the converter.

8. The converter phase control system according to claim 6, characterized in that: The first current measuring device is used to measure the three-phase AC current output by the converter, and the second current measuring device is used to measure the three-phase AC current filtered by the filter.

9. The converter phase control system according to claim 6, characterized in that: The controller is electrically connected to the first current measuring device, the second current measuring device, and the DC voltage measuring device, and is used to obtain the DC voltage of the converter, the three-phase AC current output by the converter, and the three-phase AC current filtered by the filter.

10. The converter phase control system according to claim 6, characterized in that: The controller includes a historical data analysis module, a control strategy analysis module, an alarm record analysis module and a data import and export module.

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