Multi-harmonic absorption multiplexing of grid-forming converter and its passive device limit utilization method

Abstract

The application discloses a method for multiplexing and utmost limit use of passive devices of a network-constructing type converter multi-harmonic absorption, which comprises the following steps: determining a corresponding target function according to a pre-established passive device loss model under a network-constructing type converter multi-harmonic absorption multiplexing control architecture; the target function at least comprises a passive device utmost limit use target function and a harmonic weight target function; based on real-time measurement obtained active power and reactive power, the passive device utmost limit use target function and the harmonic weight target function are iteratively solved by using a preset multi-objective optimization algorithm to obtain a target harmonic absorption current instruction; and the network-constructing type converter is controlled for harmonic absorption multiplexing based on the target harmonic absorption current instruction. The time-varying nature of the active working condition of the network-constructing type converter is fully utilized, the additional capacity of the network-constructing type converter is multiplexed to absorb the grid harmonic, the utmost limit use of the passive device of the network-constructing type converter is realized, the utilization rate of the network-constructing type converter is improved, the grid harmonic level is reduced, and the power quality of the grid is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of grid-connected technology, and particularly relates to a grid-constructing converter multi-harmonic absorption multiplexing and a method for full utilization of passive devices. BACKGROUND

[0002] In the prior art, the active power output condition of the converter of the grid-constructing converter varies with time, and in most operating time, it does not reach the rated value or the maximum value, and there is a waste of converter capacity. Therefore, it has high research value and practical value to effectively multiplex the additional capacity of the converter for grid harmonic absorption.

[0003] However, the residual capacity of the converter is not simply the algebraic addition or subtraction of kW or kVA as currently understood in the industry. For the grid-constructing converter, the question of how much capacity is consumed by the harmonics needs to add the losses of passive devices caused by multiple harmonics and fundamental power to evaluate whether it reaches the maximum allowed loss and heat. In the mixture of multiple harmonic currents, the total loss of the passive devices of the grid-constructing converter is not the sum of the losses of each harmonic calculated separately, and there is a complex coupling relationship between the harmonic loss models, which leads to the passive devices cannot be fully used. Therefore, how to effectively multiplex the residual capacity of the converter for harmonic absorption on the grid-constructing control architecture, while realizing the full utilization of the passive devices is a problem to be solved. SUMMARY

[0004] The present application provides a grid-constructing converter multi-harmonic absorption multiplexing and a method for full utilization of passive devices, to solve the problem that the residual capacity of the converter cannot be effectively multiplexed for harmonic absorption on the grid-constructing control architecture, and the passive devices cannot be fully utilized.

[0005] According to an aspect of the present application, a grid-constructing converter multi-harmonic absorption multiplexing and a method for full utilization of passive devices are provided, the method comprising:

[0006] According to the pre-established passive device loss model under the grid-constructing converter multi-harmonic absorption multiplexing control architecture, a corresponding objective function is determined; wherein the objective function at least includes: a passive device full utilization objective function and a harmonic weight objective function; the grid-constructing converter multi-harmonic absorption multiplexing control architecture includes: a basic grid-constructing control architecture, a current harmonic component calculation module and a harmonic compensation calculation module;

[0007] Based on the real-time measurement obtained active power and reactive power, the passive device full utilization objective function and the harmonic weight objective function are iteratively solved by using a pre-set multi-objective optimization algorithm, to obtain a target harmonic absorption current instruction;

[0008] Based on the target harmonic absorption current instruction, the grid-constructing converter is controlled for harmonic absorption multiplexing.

[0009] According to another aspect of the present application, there is provided a device for grid-forming converter multi-harmonic absorption multiplexing and passive device full utilization, comprising:

[0010] a target function determination module configured to determine a corresponding target function according to a pre-established passive device loss model under a control architecture of the grid-forming converter multi-harmonic absorption multiplexing; wherein the target function comprises at least a passive device full utilization target function and a harmonic weight target function; and the control architecture of the grid-forming converter multi-harmonic absorption multiplexing comprises a basic grid-forming control architecture, a current harmonic component calculation module and a harmonic compensation calculation module;

[0011] an instruction solving module configured to solve the passive device full utilization target function and the harmonic weight target function by using a pre-set multi-objective optimization algorithm based on real-time measurement of active power and reactive power, to obtain a target harmonic absorption current instruction;

[0012] a harmonic absorption multiplexing control module configured to control the grid-forming converter based on the target harmonic absorption current instruction.

[0013] According to another aspect of the present application, there is provided an electronic device, comprising:

[0014] at least one processor; and

[0015] a memory in communication connection with the at least one processor; wherein

[0016] the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the grid-forming converter multi-harmonic absorption multiplexing and passive device full utilization method according to any one of the embodiments of the present application.

[0017] According to another aspect of the present application, there is provided a computer readable storage medium storing computer instructions for enabling a processor to implement the grid-forming converter multi-harmonic absorption multiplexing and passive device full utilization method according to any one of the embodiments of the present application when executed by the processor.

[0018] The technical scheme of the embodiment of the present application determines the corresponding passive device limit use target function and harmonic weight target function according to the passive device loss model under the pre-established network configuration type converter multi-harmonic absorption multiplexing control architecture, takes the real-time measured active power and reactive power under the current working condition as the input of the preset multi-objective optimization algorithm, and obtains the optimal target harmonic absorption current instruction after iteratively solving the passive device limit use target function and the harmonic weight target function. Then, the network configuration type converter is controlled based on the target harmonic absorption current instruction for harmonic absorption multiplexing, thereby solving the problem that the residual capacity of the converter cannot be effectively multiplexed for harmonic absorption under the network configuration type control architecture, and the passive device cannot be used to the limit. The time-varying nature of the active working condition of the network configuration type converter is fully utilized, the additional capacity is multiplexed to absorb the grid harmonic, the limit use of the passive device is realized, the utilization rate of the network configuration type converter is improved, the grid harmonic level is reduced, and therefore the power quality of the grid is improved.

[0019] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a structural schematic diagram of a network configuration type converter multi-harmonic absorption multiplexing control architecture according to the first embodiment of the present application;

[0022] Figure 2 is a flowchart of a network configuration type converter multi-harmonic absorption multiplexing and passive device limit use method according to the first embodiment of the present application;

[0023] Figure 3 is a flowchart of a network configuration type converter multi-harmonic absorption multiplexing and passive device limit use method according to the second embodiment of the present application;

[0024] Figure 4 is a flowchart of another network configuration type converter multi-harmonic absorption multiplexing and passive device limit use method according to the second embodiment of the present application;

[0025] Figure 5 is a circuit model schematic diagram of a capacitor according to the second embodiment of the present application;

[0026] Figure 6 is a schematic diagram of the relationship between the equivalent series resistance of the capacitor and the frequency according to the second embodiment of the present application;

[0027] Figure 7 is a structural schematic diagram of a network type converter multi-harmonic absorption multiplexing and passive device utmost limit use device according to the third embodiment of the present application;

[0028] Figure 8 is a structural schematic diagram of an electronic device for implementing the method of the network type converter multi-harmonic absorption multiplexing and passive device utmost limit use according to the third embodiment of the present application. DETAILED DESCRIPTION

[0029] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] Embodiment One

[0032] Figure 1 is a structural schematic diagram of a network type converter multi-harmonic absorption multiplexing control architecture provided for the first embodiment of the present application. As shown in the figure, the network type converter multi-harmonic absorption multiplexing control architecture of the present embodiment includes the following two parts: Figure 1

[0033] (1) Basic network type control architecture:

[0034] Based on the basic network type control architecture, the filter capacitor voltage u c connected by the network type converter and the grid side current i2 can be sampled and input to the instantaneous power calculation module to determine the instantaneous active power P​out and instantaneous reactive power Q out ; then the instantaneous active power P out and the instantaneous reactive power Q out and the given preset active power P set and the preset reactive power Q set are input to the power ring, and by simulating the rotor motion and excitation characteristics of the synchronous generator, the reference voltage amplitude V ref and the virtual angular frequency ω m are generated, and then the virtual angular frequency ω m is integrated to obtain the reference voltage phase θ ref ; then the reference voltage amplitude V ref and the reference voltage phase θ ref are input to the voltage instruction calculation module to obtain the reference voltage instruction u ref ; the reference voltage instruction u ref is transmitted to the instruction side of the voltage and current double closed loop control module as the fundamental reference voltage, so as to realize the basic grid-forming type control. Figure 1 , G u is the transfer function of the voltage outer loop controller, and G i is the transfer function of the current inner loop controller.

[0035] (2) Multi-harmonic absorption multiplexing control architecture:

[0036] By sending the sampled grid-side current i2 into the current harmonic component calculation module, the grid-side current harmonic component i gh is calculated, and then after the difference between the input harmonic absorption current instruction i ref.h and the grid-side current harmonic component i gh is subtracted, the harmonic voltage instruction u ref.h is generated through the harmonic compensation calculation module in a closed loop; then the harmonic voltage instruction u ref.h is superimposed with the aforementioned reference voltage instruction u ref , and after voltage and current double closed loop control and pulse width modulation (PWM), the multi-harmonic absorption multiplexing control architecture of the grid-forming type converter realizes the multi-harmonic absorption multiplexing of the grid-forming type converter.

[0037] Based on the above multi-harmonic absorption multiplexing control architecture of the grid-forming type converter, Figure 2A flowchart of a network-constructed converter multi-harmonic absorption multiplexing and passive device limit usage method is provided for the first embodiment of the present application. The first embodiment can be applied to the case of using a network-constructed converter for harmonic absorption multiplexing to achieve the limit usage of passive devices. The method can be executed by a network-constructed converter multi-harmonic absorption multiplexing and passive device limit usage device, which can be realized in the form of hardware and / or software and can be configured in an electronic device. As shown in FIG. 1, the network-constructed converter multi-harmonic absorption multiplexing and passive device limit usage method provided by the first embodiment specifically includes the following steps. Figure 2

[0038] S110, determine a corresponding target function according to a passive device loss model under a network-constructed converter multi-harmonic absorption multiplexing control architecture. The target function at least includes a passive device limit usage target function and a harmonic weight target function. The network-constructed converter multi-harmonic absorption multiplexing control architecture includes a basic network-constructed control architecture, a current harmonic component calculation module, and a harmonic compensation calculation module.

[0039] The passive device can at least include a network-constructed converter DC side capacitor. The passive device loss model can be constructed based on the loss caused by the fundamental current and low-frequency harmonic current (i.e., harmonic absorption current instruction) of the converter AC side on the passive device. The passive device loss model can at least include a converter DC side capacitor loss model.

[0040] The target function can be a double optimization target for representing that the passive device loss of the network-constructed converter reaches the upper limit and meets the harmonic weight proportion allocation. The target function can at least include a passive device limit usage target function and a harmonic weight target function. The passive device limit usage target function can be used to represent the loss of the passive device of the network-constructed converter. The harmonic weight target function can be used to represent the harmonic weight proportion allocation.

[0041] In the embodiments of the present application, the network-constructed converter multi-harmonic absorption multiplexing control architecture can be constructed based on Figure 1 the network-constructed converter DC side capacitor and other passive devices, and the corresponding passive device loss model, such as the converter DC side capacitor loss model, is established. At the same time, a target function is established with the optimization target of the passive device loss reaching the upper limit and meeting the harmonic weight proportion allocation. The target function at least includes a passive device limit usage target function and a harmonic weight target function.

[0042] ​S120, based on the active power and the reactive power obtained by real-time measurement, iteratively solving the passive device limit use objective function and the harmonic weight objective function by using a preset multi-objective optimization algorithm to obtain a target harmonic absorption current instruction.

[0043] The preset multi-objective optimization algorithm can be a method for solving an optimization problem of multiple objective functions, and examples of the preset multi-objective optimization algorithm can include but are not limited to a particle swarm optimization algorithm, a genetic algorithm, a differential evolution algorithm, and a simulated annealing algorithm.

[0044] The target harmonic absorption current instruction can be an optimal harmonic absorption current instruction (i.e. ref.h ) of the current converter active working condition determined by the preset multi-objective optimization algorithm. Figure 1 The target harmonic absorption current instruction can meet the double optimization objectives of reaching the upper limit of the passive device loss (passive limit use) and meeting the harmonic weight proportional distribution (multi-harmonic absorption) of each harmonic.

[0045] In the embodiment of the application, the active power P out and the reactive power Q out output by the converter under the multi-harmonic absorption multiplexing control architecture of the grid-forming converter can be collected by a grid data acquisition device, and the active power P out and the reactive power Q out are taken as inputs of the preset multi-objective optimization algorithm to iteratively solve the passive device limit use objective function and the harmonic weight objective function, so as to obtain the target harmonic absorption current instruction that meets the double optimization objectives of reaching the upper limit of the passive device loss (passive limit use) and meeting the harmonic weight proportional distribution (multi-harmonic absorption) of each harmonic.

[0046] In the embodiment of the application, after the target harmonic absorption current instruction is determined, the grid-forming converter can be controlled based on the target harmonic absorption current instruction.

[0047] In the embodiment of the application, after the target harmonic absorption current instruction is determined, the grid-forming converter can be controlled based on the target harmonic absorption current instruction. Figure 1The shown networked converter multi-harmonic absorption multiplexing control architecture will determine the target harmonic absorption current instruction i ref.h The network side current harmonic component i gh After the difference, the harmonic compensation calculation module is closed loop to generate the harmonic voltage instruction u ref.h ; Then the harmonic voltage instruction u ref.h And the reference voltage instruction u ref Voltage and current double closed loop control and PWM modulation, and then control the networked converter to realize multi-harmonic absorption multiplexing. Based on the target harmonic absorption current instruction, the harmonic absorption of the networked converter can be realized under the working condition change of active and reactive power, so as to realize the limit use of passive device, thereby improving the utilization rate of networked converter and reducing the harmonic level of power grid.

[0048] The technical scheme of the embodiment of the application, by means of the passive device loss model under the pre-established networked converter multi-harmonic absorption multiplexing control architecture, determines the corresponding passive device limit use target function and harmonic weight target function, and then takes the real-time measured active power and reactive power under the current working condition as the input of the preset multi-objective optimization algorithm, iteratively solves the passive device limit use target function and harmonic weight target function to obtain the best target harmonic absorption current instruction, and then controls the harmonic absorption multiplexing of the networked converter based on the target harmonic absorption current instruction, solves the problem that the remaining capacity of the converter cannot be effectively multiplexed for harmonic absorption under the networked control architecture, and the passive device cannot be used to the limit, fully utilizes the time-varying nature of the active working condition of the networked converter, multiplexes the additional capacity to absorb the harmonic of the power grid, realizes the limit use of the passive device, improves the utilization rate of the networked converter, and reduces the harmonic level of the power grid, thereby improving the power quality of the power grid.

[0049] Embodiment two

[0050] Figure 3 The flowchart of the networked converter multi-harmonic absorption multiplexing and passive device limit use method provided by the embodiment two of the application is based on the above-mentioned embodiment for further optimization and expansion, and can be combined with each optional technical scheme in the above-mentioned embodiment. As Figure 3 As shown in the embodiment two, the networked converter multi-harmonic absorption multiplexing and passive device limit use method provided by the embodiment two specifically includes the following steps:

[0051] S210, obtaining the passive device loss model under the pre-established networked converter multi-harmonic absorption multiplexing control architecture, and obtaining the pre-configured harmonic weight target function.

[0052] In the embodiment of the application, the passive device loss model under the pre-established networked converter multi-harmonic absorption multiplexing control architecture can be obtained from a local or cloud server or other data storage location.Figure 1 The passive device loss model and the harmonic weight objective function are pre-constructed under the multi-harmonic absorption multiplexing control architecture of the grid-forming converter, and the passive device at least includes a capacitor on a direct current side of the converter.

[0053] Further, on the basis of the above-mentioned embodiments, the passive device loss model can be expressed as:

[0054]

[0055] In the formula, P cap is the total loss of the passive device (model), that is, the total loss of the capacitor on the direct current side of the converter; I C,rms is the total effective value of the current flowing through; R ESR is the equivalent series resistance of the capacitor; f1 is the fundamental frequency; I C,rms_LOH is the total effective value of the low-frequency harmonic current on the direct current side of the converter; I C,rms_SHC is the total effective value of the high-frequency harmonic current on the direct current side of the converter; represents the loss caused by the low-frequency harmonic component, that is, the effective value of the current on the direct current side of the grid-forming converter caused by the fundamental current plus the low-frequency harmonic current (that is, the harmonic absorption current instruction for multi-harmonic absorption multiplexing) on the alternating current side on the capacitor; represents the loss caused by the high-frequency harmonic component, that is, the loss caused by the effective value of the high-frequency switching harmonic current on the direct current side of the grid-forming converter shaped by the fundamental current plus the low-frequency harmonic current (that is, the harmonic absorption current instruction for multi-harmonic absorption multiplexing) on the alternating current side.

[0056] Further, the effective value I C,rms of the total current on the direct current side of the converter can be expressed as:

[0057]

[0058] In the formula, V is the modulation ratio of the fundamental component in the alternating current side voltage; k and n are respectively the positive sequence harmonic order and the negative sequence harmonic order; is the positive sequence component of the amplitude of the k-th harmonic of the alternating current side harmonic current; is the negative sequence component of the amplitude of the n-th harmonic of the alternating current side harmonic current; is the positive sequence phase angle component of the k-th harmonic of the alternating current side harmonic current; is the negative sequence phase angle component of the n-th harmonic of the alternating current side harmonic current.

[0059] Further, the total effective value I C,rms_LOH of the low-frequency harmonic current on the direct current side of the converter can be expressed as:

[0060]

[0061] Further, the total effective value I of the high-frequency harmonic current on the DC side of the converter C,rms_SHC may be expressed as:

[0062]

[0063] Further, on the basis of the above-mentioned embodiments, the harmonic weight target function can be expressed as:

[0064]

[0065] wherein Q represents the harmonic weight target function; k represents the harmonic order; h k represents the k-th harmonic importance weight coefficient; I k represents the k-th harmonic absorption current amplitude.

[0066] Further, the k-th harmonic importance weight coefficient h k may be expressed as:

[0067]

[0068] In the formula, α j is the sensitivity factor of the j-th harmonic.

[0069] S220, determining the corresponding passive device limit use target function based on the difference between the passive device loss model and the pre-configured passive device limit loss value.

[0070] In the embodiments of the present application, the corresponding passive device limit use target function can be determined based on the aforementioned obtained passive device loss model and the pre-configured passive device limit loss value.

[0071] Further, on the basis of the above-mentioned embodiments, the passive device limit use target function can be expressed as:

[0072] minδ=|P cap -P capN |;

[0073] wherein δ represents the passive device limit use target function; P cap represents the passive device loss; P capN represents the passive device limit loss value.

[0074] S230, obtaining the active power and the reactive power obtained by real-time measurement under the multi-harmonic absorption multiplexing control architecture of the network construction type converter, and determining the corresponding fundamental current real-time value according to the active power and the reactive power by calling the pre-set fundamental current calculation formula.

[0075] In this embodiment of the invention, the active power P under the current operating condition of the multi-harmonic absorption and multiplexing control architecture of the grid-type converter can be collected by a power grid data acquisition device. out and reactive power Q out Then, the active power P is determined by calling the following preset fundamental current calculation formula. out and reactive power Q out The corresponding real-time value of the fundamental current I:

[0076]

[0077] In the formula, U is the three-phase line voltage.

[0078] S240. Obtain the optimization constraints and iteration termination conditions corresponding to the particle swarm optimization algorithm.

[0079] The optimization constraint can refer to the conditions used to limit the solution space (i.e., harmonic absorption current command) corresponding to the objective function. In this embodiment, the optimization constraint can be: the loss value of passive devices cannot exceed their rated loss, that is, the loss P of passive devices. cap It cannot exceed the corresponding passive device limit loss value P capN .

[0080] The iteration termination condition can refer to the execution termination condition of the preset particle swarm optimization algorithm. The iteration termination condition can include: the number of iterations reaches the preset maximum number of iterations, the fitness value deviation between two iterations reaches the preset stopping tolerance (that is, the difference between the fitness value of the optimal solution after the previous iteration and the fitness value of the optimal solution after the current iteration is less than the preset value), etc.

[0081] In this embodiment of the invention, the optimization constraints and iteration termination conditions corresponding to the particle swarm optimization algorithm to be called later can be obtained from data storage locations such as local or cloud servers.

[0082] Furthermore, the optimization constraints can be expressed as: stP cap <P capN .

[0083] S250. Treat the harmonic absorption current command to be solved as a particle in the particle swarm, and initialize the position and velocity of each particle based on the optimization constraints.

[0084] In this embodiment of the invention, a pre-configured particle swarm optimization algorithm can be invoked, treating the harmonic absorption current command as a particle in the particle swarm. An initialization operation is performed based on optimization constraints, i.e., initialization settings include: population size (number of particles), particle dimension (the spatial dimension of the particle search, i.e., the dimension of the parameter to be optimized), position of each particle (a solution to the optimization problem, i.e., a specific harmonic absorption current command), velocity, individual extremum (individual optimal solution), preset maximum number of iterations, and swarm extremum (global optimal solution). The i-th particle in the particle swarm can be represented as follows:

[0085]

[0086] In the formula, I i The amplitude of the i-th harmonic absorption current; The phase of the i-th harmonic absorption current.

[0087] S260. Based on the objective function of limiting the use of passive devices, the objective function of harmonic weighting, and the real-time value of the fundamental current, the fitness value corresponding to each particle is determined.

[0088] In this embodiment of the invention, the objective function and harmonic weight objective function of the passive device can be used as the fitness function of the preset particle swarm optimization algorithm. Then, the real-time value of the fundamental current and the amplitude and phase of each harmonic absorption current corresponding to each particle in the current iteration are substituted into the fitness function to obtain the fitness value of each particle in the current iteration.

[0089] S270. Update the individual extreme values ​​of the corresponding particles and the population extreme values ​​of the particle swarm using the fitness value.

[0090] Here, the individual extreme value can refer to the individual optimal solution for a particle in that iteration. The swarm extreme value can refer to the global optimal solution for the particle swarm.

[0091] In this embodiment of the invention, S270 may specifically include:

[0092] If the fitness value of a particle is greater than the fitness value corresponding to the particle's individual extreme value, then the particle's individual extreme value is updated in this iteration using the particle's position.

[0093] If the fitness value of a particle is less than the fitness value corresponding to the individual extreme value of the particle, then the individual extreme value of the particle remains unchanged in this iteration;

[0094] If the fitness value of a particle is greater than the fitness value corresponding to the population extremum of the particle swarm, then the population extremum of the particle swarm is updated in this iteration using the position of the particle.

[0095] If the fitness value of a particle is less than the fitness value corresponding to the population extremum of the particle swarm, then the population extremum of the particle swarm remains unchanged in this iteration.

[0096] It is important to understand that in the preset particle swarm optimization algorithm (multi-objective particle swarm optimization algorithm) of this embodiment, the position and velocity of the particles are still updated according to the method of the single-objective particle swarm optimization algorithm. The difference between the single-objective particle swarm optimization algorithm and the multi-objective particle swarm optimization algorithm is that the final result of the single-objective particle swarm optimization algorithm is only one solution, while the final result of the multi-objective particle swarm optimization algorithm is a set of Pareto optimal solutions composed of a series of Pareto optimal solutions.

[0097] In the preset particle swarm optimization algorithm of this embodiment, the update strategy of individual extreme values ​​(individual optimal solutions) is as follows: when the new solution generated by the particle is dominated by the old solution, the individual extreme value remains unchanged; when the new solution is dominant over the old solution, the new solution is adopted as the individual extreme value; and when the new solution and the old solution are not dominant, a solution is randomly selected as the individual extreme value.

[0098] The update strategy for the population extremum (global optimal solution) is as follows: after each iteration, as the particle position is updated, the Pareto optimal solution set is also updated, and a particle is randomly selected from the updated Pareto solution as the population extremum for the next iteration.

[0099] S280. Update the velocity and position of each particle using individual extreme values ​​and group extreme values, as well as the number of iterations.

[0100] In this embodiment of the invention, a pre-configured particle velocity and position update formula can be invoked to update the velocity and position of each particle, and the number of iterations can also be updated.

[0101] Furthermore, the formulas for updating particle velocity and position can be expressed as follows:

[0102]

[0103] In the formula, v ij (t) represents the j-th dimension velocity component of the i-th particle during the t-th iteration; x ij (t) represents the j-th position component of the i-th particle during the t-th iteration; ω inertia c1 is the inertia coefficient, used to control the influence of the particle's previous velocity on its current velocity; it affects the particle's global and local search capabilities. c2 is the individual learning coefficient. c3 is the global learning coefficient. r1 and r2 are two independent random numbers in the interval [0,1]. p ij (t) represents the individual extreme value of the i-th particle; p gj (t) represents the population extremum of the particle swarm.

[0104] S290. If the updated iteration number satisfies the iteration termination condition, output the Pareto optimal solution set corresponding to the current iteration number, and determine the target harmonic absorption current command in the Pareto optimal solution set according to the preset weight coefficients corresponding to the objective function and harmonic weight objective function for the limited use of passive devices.

[0105] In this embodiment of the invention, during the iteration process of the particle swarm optimization algorithm, it can be detected whether the current iteration number meets the iteration termination condition. If the condition is met, the Pareto optimal solution set corresponding to the current iteration number is directly output. Based on the passive device, the preset weight coefficients corresponding to the objective function and harmonic weight objective function are used to the fullest extent. The best global optimal solution is selected from the above Pareto optimal solution set, which is the final target harmonic absorption current command.

[0106] Furthermore, in S290, the target harmonic absorption current command is determined in the Pareto optimal solution set according to the preset weighting coefficients corresponding to the passive device's maximum utilization objective function and the harmonic weight objective function. This specifically includes the following steps:

[0107] A. Determine the first fitness value of the objective function for the passive device to be used to the maximum extent possible for each Pareto optimal solution in the Pareto optimal solution set, and the second fitness value of the objective function for the harmonic weighting;

[0108] B. For each Pareto optimal solution, determine the first product between the first fitness value and the corresponding first preset weight coefficient, and the second product between the second fitness value and the corresponding second preset weight coefficient, and use the sum of the first product and the second product as the objective function weight value;

[0109] C. Iterate through the objective function weight values ​​corresponding to each Pareto optimal solution, and take the Pareto optimal solution with the largest objective function weight value as the target harmonic absorption current command.

[0110] S2100. If the updated iteration count does not meet the iteration termination condition, return to the step of determining the fitness value corresponding to each particle based on the objective function of using passive devices to the maximum extent, the harmonic weight objective function, and the real-time value of the fundamental current.

[0111] In this embodiment of the invention, if it is detected that the current iteration does not meet the iteration termination condition and the maximum number of iterations has not been reached, the process returns to the step in S260 to execute the next iteration of the optimization algorithm.

[0112] S2110, Harmonic absorption and multiplexing control of grid-type converter based on target harmonic absorption current command.

[0113] Figure 4This is a flowchart illustrating another method for multi-harmonic absorption and multiplexing in a grid-type converter and its method for maximizing the use of passive devices, provided in Embodiment 2 of the present invention. Figure 4 As shown, the method mainly includes the following steps:

[0114] 1. Establish a multi-harmonic absorption and multiplexing control architecture for grid-type converters;

[0115] 2. Establish a passive device loss model for the grid-type converter output containing multiple harmonic combinations, where the real-time value of the fundamental current and the absorption current of each harmonic are the inputs, and the passive device loss power value is the output.

[0116] 3. Calculate the real-time value of the fundamental current based on the active and reactive power obtained from real-time measurements, input it into the particle swarm optimization module, and iteratively solve the harmonic absorption current command.

[0117] 4. Each iteration of the particle swarm optimization module is based on the input of multiple harmonic current combinations in the current iteration, and the loss of passive devices in the grid converter is calculated through the passive device loss model.

[0118] 5. Obtain a combination of multiple harmonic current absorption command values ​​(i.e., target harmonic absorption current command) by particle swarm iteration calculation to achieve the upper limit of passive device loss in the grid-type converter and meet the dual optimization objectives of harmonic weight ratio allocation.

[0119] 6. Based on the determined target harmonic absorption current command, the converter is controlled to perform harmonic absorption and multiplexing.

[0120] It should be noted that, under the condition of a large grid harmonic current distribution, the embodiment of the present invention uses the dynamic surplus capacity of the grid-type converter to reuse and absorb grid harmonics based on the condition of compensating for all possible harmonics.

[0121] The technical solution of this invention, based on the passive device loss model constructed under the multi-harmonic absorption and reuse control architecture of the grid-type converter, determines the corresponding objective function for maximizing the use of passive devices and the harmonic weight objective function. Then, the real-time value of the fundamental current determined under the current operating condition and the harmonic absorption current command to be solved (each harmonic absorption current) are used as inputs to the particle swarm optimization algorithm. After continuous iterative solution, the optimal target harmonic absorption current command is obtained. Then, based on the target harmonic absorption current command, the grid-type converter is subjected to harmonic absorption and reuse control. This solves the problem that the remaining capacity of the converter cannot be effectively reused for harmonic absorption in the grid-type control architecture, and the passive devices cannot be fully utilized. It makes full use of the time-varying nature of the active power condition of the grid-type converter, reuses its additional capacity to absorb grid harmonics, so as to realize the maximum utilization of its passive devices, improve the utilization rate of the grid-type converter, and reduce the grid harmonic level, thereby improving the power quality of the grid.

[0122] To enable those skilled in the art to better understand the embodiments of the present invention, the specific derivation process of the passive device loss model is given below.

[0123] The passive components of a grid-type converter are mainly DC-side capacitors, and the losses of these capacitors during operation primarily include dielectric losses and metal losses. Dielectric losses include polarization losses and conduction losses caused by dielectric leakage current; metal losses include losses caused by heating of the metal plates and wires, as well as contact resistance between the metal plates and wires. The circuit model of an actual capacitor is as follows: Figure 5 As shown, it consists of an equivalent series resistor (ESR), a capacitor (C), and an equivalent series inductor (ESL).

[0124] Therefore, the capacitor's loss can be expressed as:

[0125] Depend on Figure 6 The schematic diagram showing the relationship between the capacitor's equivalent series resistance and frequency reveals that when the capacitor's ESR is below 1kHz, its resistance decreases significantly with increasing frequency; however, when the frequency is above 1kHz, its resistance remains essentially constant with increasing frequency. Therefore, the capacitor's power loss can be expressed as:

[0126]

[0127] In the above equation, the first part on the right side represents the loss caused by low-frequency harmonic components, and the second part represents the loss caused by high-frequency harmonic components. The harmonic loss caused by low-frequency harmonic currents on the DC side can be calculated individually using each low-frequency harmonic current at the DC port; the loss caused by high-frequency harmonic currents can be calculated using the total effective value of the high-frequency harmonic currents on the DC side.

[0128] Based on the basic topology of a grid-connected converter, the current expression on the AC side of the grid-connected converter can be determined as follows:

[0129]

[0130] In the formula, ω1 is the fundamental angular frequency. The first part on the right side of the above formula represents the AC side harmonic current, and the second part i sw This indicates that a series of high-frequency harmonic currents are generated at the AC port by the PWM modulation process. The high-frequency components of the AC side current are negligible. By performing positive and negative sequence decomposition on the AC side harmonic currents, the current expression can be obtained as follows:

[0131]

[0132] In the formula, the superscripts “+” and “-” represent the positive and negative sequence components of the current, respectively; k and n are the harmonic orders.

[0133] During any switching cycle, the low-frequency harmonic current i on the DC side C_LOH The unified mathematical model is:

[0134]

[0135] The analytical expression for the low-frequency harmonic current under the mixed output of low-order harmonic current and converter fundamental current can be obtained as follows:

[0136]

[0137] Therefore, the total effective value of the low-frequency harmonic current on the DC side of the grid converter is calculated as follows:

[0138]

[0139] The effective value of the total DC-side current of a grid-type converter can be expressed as:

[0140]

[0141] Among them, u max u med and u min They are represented as follows:

[0142]

[0143]

[0144] By integrating and simplifying the effective value of the total DC-side current of the grid-type converter, we can obtain that the effective value of the total DC-side current is divided into 5 parts:

[0145]

[0146] in,

[0147]

[0148]

[0149] After simplification, the effective value of the total DC current can be expressed as:

[0150]

[0151] By removing the contribution of the low-frequency harmonic current to the effective value of the total DC-side current of the grid-type converter in the above formula, the effective value of the high-frequency harmonic current on the DC side can be derived as follows:

[0152]

[0153] In summary, after simplification, the capacitor loss is:

[0154]

[0155] Example 3

[0156] Figure 7 This is a schematic diagram of the structure of a grid-type converter multi-harmonic absorption and multiplexing device and its passive device limitation device provided in Embodiment 3 of the present invention. Figure 7 As shown, the device includes:

[0157] The objective function determination module 31 is used to determine the corresponding objective function based on the passive device loss model under the pre-established multi-harmonic absorption and multiplexing control architecture of the grid-type converter; wherein, the objective function includes at least: the objective function for the limited use of passive devices and the harmonic weight objective function; the multi-harmonic absorption and multiplexing control architecture of the grid-type converter includes: the basic grid-type control architecture, the current harmonic component calculation module and the harmonic compensation calculation module;

[0158] The instruction solving module 32 is used to iteratively solve the objective function and harmonic weight objective function of passive devices based on the active power and reactive power obtained by real-time measurement, and obtain the target harmonic absorption current instruction by using a preset multi-objective optimization algorithm.

[0159] The harmonic absorption and multiplexing control module 33 is used to perform harmonic absorption and multiplexing control on the grid-type converter based on the target harmonic absorption current command.

[0160] The technical solution of this invention, based on a pre-established passive device loss model under a multi-harmonic absorption and reuse control architecture for a grid-type converter, determines the corresponding objective function for maximizing the use of passive devices and the harmonic weight objective function. Then, using the active and reactive power measured in real-time under the current operating conditions as input to a pre-defined multi-objective optimization algorithm, the optimal target harmonic absorption current command is obtained by iteratively solving the objective function for maximizing the use of passive devices and the harmonic weight objective function. Based on this target harmonic absorption current command, the grid-type converter is subjected to harmonic absorption and reuse control. This solves the problem that the remaining capacity of the converter cannot be effectively reused for harmonic absorption in a grid-type control architecture, and that passive devices cannot be maximized. It fully utilizes the time-varying nature of the active power condition of the grid-type converter, reuses its additional capacity to absorb grid harmonics, thereby maximizing the use of its passive devices, improving the utilization rate of the grid-type converter, reducing the level of grid harmonics, and thus improving the power quality of the grid.

[0161] Furthermore, based on the above embodiments of the invention, the objective function determination module 31 includes:

[0162] The passive device loss model and harmonic weight objective function acquisition unit is used to acquire the passive device loss model under the pre-established multi-harmonic absorption multiplexing control architecture of the grid-type converter, and to acquire the pre-configured harmonic weight objective function.

[0163] The passive device limit use objective function determination unit is used to determine the corresponding passive device limit use objective function based on the difference between the passive device loss model and the pre-configured passive device limit loss value.

[0164] The preset multi-objective optimization algorithm includes at least: particle swarm optimization algorithm; correspondingly, the instruction solver module 32 includes:

[0165] The fundamental current real-time value determination unit is used to obtain the active power and reactive power measured in real time under the multi-harmonic absorption and multiplexing control architecture of the grid-type converter, and to determine the corresponding fundamental current real-time value according to the preset fundamental current calculation formula based on the active power and reactive power.

[0166] The condition acquisition unit is used to acquire the optimization constraints and iteration termination conditions corresponding to the particle swarm optimization algorithm.

[0167] The initialization unit is used to treat the harmonic absorption current command to be solved as a particle in the particle swarm, and initialize the position and velocity of each particle based on the optimization constraints.

[0168] The fitness value determination unit is used to determine the fitness value corresponding to each particle based on the objective function of maximizing the use of passive devices, the objective function of harmonic weighting, and the real-time value of the fundamental current.

[0169] The extreme value update unit is used to update the individual extreme values ​​of the corresponding particles and the population extreme values ​​of the particle swarm using the fitness value;

[0170] The update unit is used to update the velocity and position of each particle using individual and group extreme values, as well as the number of iterations.

[0171] The first processing unit is used to output the Pareto optimal solution set corresponding to the current iteration number if the updated iteration number meets the iteration termination condition, and determine the target harmonic absorption current command in the Pareto optimal solution set according to the preset weight coefficients corresponding to the passive device limit use objective function and harmonic weight objective function.

[0172] The second processing unit is used to return to the step of determining the fitness value corresponding to each particle based on the objective function of the passive device's maximum use, the harmonic weight objective function, and the real-time value of the fundamental current if the updated iteration number does not meet the iteration termination condition.

[0173] Furthermore, based on the above embodiments of the invention, according to the preset weighting coefficients corresponding to the objective function of maximizing the use of passive devices and the objective function of harmonic weighting, the target harmonic absorption current command is determined in the Pareto optimal solution set, including:

[0174] Determine the first fitness value of the objective function for the maximum use of passive devices for each Pareto optimal solution in the Pareto optimal solution set, and the second fitness value of the objective function for the corresponding harmonic weighting.

[0175] For each Pareto optimal solution, determine the first product between the first fitness value and the corresponding first preset weight coefficient, and the second product between the second fitness value and the corresponding second preset weight coefficient, and use the sum of the first product and the second product as the weight value of the objective function;

[0176] Iterate through the objective function weight values ​​corresponding to each Pareto optimal solution, and take the Pareto optimal solution with the largest objective function weight value as the target harmonic absorption current command.

[0177] Furthermore, based on the above embodiments of the invention, the passive device can be represented by the objective function as follows:

[0178] minδ=|P cap -P capN |;

[0179] Where δ represents the objective function for the limited use of passive devices; P cap P represents the loss of passive components; capN This represents the maximum loss value of a passive device;

[0180] The objective function for harmonic weighting is expressed as:

[0181]

[0182] Where Q represents the harmonic weighting objective function; k represents the harmonic order; h k I represents the weighting coefficient for the importance of the k-th harmonic; k This represents the amplitude of the k-th harmonic absorption current.

[0183] Furthermore, based on the above embodiments of the invention, the passive device includes at least: a DC-side capacitor of the converter.

[0184] Furthermore, based on the above embodiments of the invention, the passive device loss model is expressed as follows:

[0185]

[0186] Among them, P cap I represents the total loss of the DC-side capacitor of the converter. C,rmsR is the total effective value of the current flowing through it. ESR f1 is the equivalent series resistance of the capacitor; f1 is the fundamental frequency. Loss caused by low-frequency harmonic components; I C,rms_LOH This represents the total effective value of the low-frequency harmonic current on the DC side of the converter.

[0187] Loss caused by high-frequency harmonic components; I C,rms_SHC This represents the total effective value of the high-frequency harmonic current on the DC side of the converter.

[0188] The multi-harmonic absorption and multiplexing device for grid-type converters and the device for maximizing the use of passive components provided in the embodiments of the present invention can execute the multi-harmonic absorption and multiplexing device for grid-type converters and the device for maximizing the use of passive components provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of executing the method.

[0189] Example 4

[0190] Figure 8 A schematic diagram of an electronic device 40 that can be used to implement embodiments of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0191] like Figure 8 As shown, the electronic device 40 includes at least one processor 41 and a memory, such as a read-only memory (ROM) 42 or a random access memory (RAM) 43, communicatively connected to the at least one processor 41. The memory stores computer programs executable by the at least one processor. The processor 41 can perform various appropriate actions and processes based on the computer program stored in the ROM 42 or loaded into the RAM 43 from storage unit 48. The RAM 43 may also store various programs and data required for the operation of the electronic device 40. The processor 41, ROM 42, and RAM 43 are interconnected via a bus 44. An input / output (I / O) interface 45 is also connected to the bus 44.

[0192] Multiple components in electronic device 40 are connected to I / O interface 45, including: input unit 46, such as keyboard, mouse, etc.; output unit 47, such as various types of monitors, speakers, etc.; storage unit 58, such as disk, optical disk, etc.; and communication unit 49, such as network card, modem, wireless transceiver, etc. Communication unit 49 allows electronic device 40 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0193] Processor 41 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 41 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 41 performs the various methods and processes described above, such as multi-harmonic absorption multiplexing in grid-type converters and its passive device-limited utilization methods.

[0194] In some embodiments, the method for multi-harmonic absorption multiplexing of a grid-type converter and the method for limiting the use of its passive components can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 48. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 40 via ROM 42 and / or communication unit 49. When the computer program is loaded into RAM 43 and executed by processor 41, one or more steps of the method for multi-harmonic absorption multiplexing of a grid-type converter and the method for limiting the use of its passive components described above can be performed. Alternatively, in other embodiments, processor 41 can be configured to perform the method for multi-harmonic absorption multiplexing of a grid-type converter and the method for limiting the use of its passive components by any other suitable means (e.g., by means of firmware).

[0195] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0196] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0197] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0198] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0199] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0200] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0201] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0202] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for maximizing the use of passive components in a grid-type converter for multi-harmonic absorption and multiplexing, characterized in that, The method includes: Based on the passive device loss model under the pre-established multi-harmonic absorption and multiplexing control architecture of the grid-type converter, the corresponding objective function is determined; wherein, the objective function includes at least: the objective function for maximizing the use of passive devices and the objective function for harmonic weighting; the multi-harmonic absorption and multiplexing control architecture of the grid-type converter includes: a basic grid-type control architecture, a current harmonic component calculation module, and a harmonic compensation calculation module; Based on the active power and reactive power obtained from real-time measurements, a preset multi-objective optimization algorithm is used to iteratively solve the objective function for the limit use of the passive device and the objective function for the harmonic weighting to obtain the target harmonic absorption current command. Harmonic absorption and multiplexing control is performed on the grid-type converter based on the target harmonic absorption current command. The preset multi-objective optimization algorithm includes at least: particle swarm optimization algorithm; The active and reactive power obtained based on real-time measurements are used to iteratively solve the objective function for the maximum use of the passive device and the objective function for harmonic weighting using a preset multi-objective optimization algorithm to obtain the target harmonic absorption current command, including: The active power and reactive power measured in real time under the multi-harmonic absorption and multiplexing control architecture of the grid-type converter are obtained, and the corresponding real-time value of the fundamental current is determined by calling the preset fundamental current calculation formula according to the active power and reactive power. Obtain the optimization constraints and iteration termination conditions corresponding to the particle swarm optimization algorithm; The harmonic absorption current command to be solved is treated as a particle in a particle swarm, and the position and velocity of each particle are initialized based on the optimization constraints. Based on the passive device limit use objective function, the harmonic weight objective function, and the real-time value of the fundamental current, the fitness value corresponding to each particle is determined; The individual extreme values ​​of the corresponding particles and the population extreme values ​​of the particle swarm are updated using the fitness value; The velocity and position of each particle are updated using the individual extreme values ​​and the group extreme values, as well as the number of iterations. If the updated iteration number satisfies the iteration termination condition, the Pareto optimal solution set corresponding to the current iteration number is output, and the target harmonic absorption current command is determined in the Pareto optimal solution set according to the preset weight coefficients corresponding to the passive device limit use objective function and the harmonic weight objective function. If the updated iteration count does not meet the iteration termination condition, then return to the step of determining the fitness value corresponding to each particle based on the objective function of maximizing the use of the passive device, the objective function of harmonic weighting, and the real-time value of the fundamental current.

2. The method according to claim 1, characterized in that, The objective function is determined based on the pre-established passive device loss model under the multi-harmonic absorption and multiplexing control architecture of the grid-type converter, including: Obtain the passive device loss model under the pre-established multi-harmonic absorption and multiplexing control architecture of the grid-type converter, and obtain the pre-configured harmonic weight objective function; Based on the difference between the passive device loss model and the pre-configured passive device limit loss value, the corresponding objective function for the passive device to be used to the fullest extent is determined.

3. The method according to claim 1, characterized in that, The step of determining the target harmonic absorption current command in the Pareto optimal solution set according to the objective function for maximizing the use of the passive device and the preset weighting coefficients corresponding to the harmonic weighting objective function includes: Determine the first fitness value of the objective function for the maximum use of the passive device corresponding to each Pareto optimal solution in the Pareto optimal solution set, and the second fitness value corresponding to the objective function for the harmonic weighting; For each Pareto optimal solution, a first product between the first fitness value and the corresponding first preset weight coefficient is determined, and a second product between the second fitness value and the corresponding second preset weight coefficient is determined. The sum of the first product and the second product is used as the weight value of the objective function. Iterate through the objective function weight values ​​corresponding to each Pareto optimal solution, and take the Pareto optimal solution with the largest objective function weight value as the target harmonic absorption current command.

4. The method according to claim 1, characterized in that, The passive device can be represented by the objective function as follows: ； in, This indicates that passive devices should use the objective function only. Indicates the loss of passive components; This represents the maximum loss value of a passive device; The harmonic weighting objective function is expressed as follows: ； Where Q represents the harmonic weighting objective function; k represents the harmonic order; This represents the weighting coefficient for the importance of the k-th harmonic; This represents the amplitude of the k-th harmonic absorption current.

5. The method according to claim 1, characterized in that, The passive device includes at least the DC-side capacitor of the converter.

6. The method according to claim 5, characterized in that, The loss model of the passive device is expressed as follows: ； in, This represents the total loss of the DC-side capacitor in the converter. This represents the total effective value of the flowing current. This is the equivalent series resistance of the capacitor; The fundamental frequency; Losses caused by low-frequency harmonic components; This represents the total effective value of the low-frequency harmonic current on the DC side of the converter. Losses caused by high-frequency harmonic components; This represents the total effective value of the high-frequency harmonic current on the DC side of the converter.

7. A multi-harmonic absorption and multiplexing device for a grid-type converter and a device for maximizing the use of its passive components, characterized in that, The device includes: The objective function determination module is used to determine the corresponding objective function based on the passive device loss model under the pre-established multi-harmonic absorption and multiplexing control architecture of the grid-type converter; wherein, the objective function includes at least: the passive device maximum utilization objective function and the harmonic weight objective function; the multi-harmonic absorption and multiplexing control architecture of the grid-type converter includes: a basic grid-type control architecture, a current harmonic component calculation module and a harmonic compensation calculation module; The instruction solving module is used to iteratively solve the passive device's limit use objective function and the harmonic weight objective function based on the active power and reactive power obtained from real-time measurements, using a preset multi-objective optimization algorithm, to obtain the target harmonic absorption current instruction. The harmonic absorption and multiplexing control module is used to perform harmonic absorption and multiplexing control on the grid-type converter based on the target harmonic absorption current command. The preset multi-objective optimization algorithm includes at least: particle swarm optimization algorithm; The instruction solving module includes: The fundamental current real-time value determination unit is used to obtain the active power and reactive power measured in real time under the multi-harmonic absorption and multiplexing control architecture of the grid-type converter, and to determine the corresponding fundamental current real-time value by calling the preset fundamental current calculation formula according to the active power and reactive power. The condition acquisition unit is used to acquire the optimization constraints and iteration termination conditions corresponding to the particle swarm optimization algorithm. An initialization unit is used to treat the harmonic absorption current command to be solved as a particle in a particle swarm, and to initialize the position and velocity of each particle based on the optimization constraints. The fitness value determination unit is used to determine the fitness value corresponding to each particle based on the passive device limit use objective function, the harmonic weight objective function, and the real-time value of the fundamental current. An extreme value update unit is used to update the individual extreme values ​​of the corresponding particles and the population extreme values ​​of the particle swarm using the fitness value; An update unit is used to update the velocity and position of each particle using the individual extreme value and the group extreme value, as well as the number of update iterations; The first processing unit is configured to output the Pareto optimal solution set corresponding to the current iteration number if the updated iteration number satisfies the iteration termination condition, and determine the target harmonic absorption current command in the Pareto optimal solution set according to the preset weight coefficients corresponding to the passive device use objective function and the harmonic weight objective function. The second processing unit is used to return to the step of determining the fitness value corresponding to each particle based on the objective function of maximizing the use of the passive device, the objective function of harmonic weighting, and the real-time value of the fundamental current if the updated iteration number does not meet the iteration termination condition.

8. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the method for multi-harmonic absorption multiplexing of the grid-type converter and the method for maximizing the use of passive devices as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the multi-harmonic absorption multiplexing of the grid-type converter and the method for maximizing the use of its passive devices as described in any one of claims 1-6.

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