Active power filter current tracking control method and system based on improved butterfly algorithm

Abstract

The invention relates to the technical field of harmonic optimization of direct current converter stations, in particular to an active power filter current tracking control method and system based on an improved butterfly algorithm. According to the method, a harmonic current tracking error is obtained through calculation, a fractional order complementary terminal sliding mode controller is constructed, a butterfly algorithm is optimized through a reverse learning strategy, a Cauchy variation strategy and a random concern weight strategy, the fractional order complementary terminal sliding mode controller is optimized through an improved butterfly optimizer, and a harmonic control function is obtained; and a control signal is obtained through calculation according to the harmonic control function, and an inverter is driven to output harmonic compensation current. And through a fractional order complementary terminal sliding mode surface, the system tracking performance is improved, and the system is enabled to realize convergence in finite time. Meanwhile, by improving a traditional butterfly optimization algorithm, the convergence precision and speed of the optimizer are improved. Therefore, the active power filter not only can well eliminate harmonic waves generated by a nonlinear load, but also meets the requirement for stability.

Description

Technical Field

[0001] The present invention relates to the technical field of harmonic optimization in DC converter stations, and particularly to a current tracking control method and system for an active power filter based on an improved butterfly algorithm. Background Art

[0002] With the rapid development of high-voltage direct current (HVDC) transmission technology, DC converter stations, as a core component of the power system, play an important role in the power system. However, power electronic devices (such as thyristors, IGBTs, etc.) in converter stations generate a large amount of harmonics during operation, which have a serious impact on the power quality, equipment safety, and communication system of the power system. Specifically, harmonics can cause voltage and current waveform distortion, thus affecting the stability of the power system; at the same time, harmonics can cause additional heating and losses in equipment such as transformers and cables, shortening the service life of the equipment; in addition, harmonics may also generate electromagnetic interference to adjacent communication lines, affecting the normal operation of the communication system. Therefore, it is of great theoretical and practical significance to control the harmonics in DC converter stations.

[0003] At present, there are mainly two methods for suppressing harmonics in DC converter stations: passive filtering technology and active filtering technology. Passive filters use an LC circuit composed of inductors and capacitors to filter out harmonics of specific frequencies. Its advantages are simple structure, low cost, and high reliability, but it has disadvantages such as large volume, easy resonance with the system, and significant influence of the filtering effect by the system impedance. In the treatment of low-order harmonics, monotonic passive filters are usually adopted, which have low cost and can effectively treat specific low-order harmonics; while in the treatment of high-order harmonics, high-pass passive filters are more applicable. However, passive filters have the limitation of compensating for a single characteristic, and can only filter out harmonics of specific frequencies, making it difficult to cope with complex harmonic environments. To overcome this limitation, dual-tuned filters have been proposed and widely used. Dual-tuned filters can filter out two specific frequencies of harmonics simultaneously, with higher filtering efficiency, suitable for occasions with complex harmonic components, and saving installation space at the same time. However, dual-tuned filters also have certain disadvantages. For example, when the system impedance changes, it may resonate with the system, resulting in harmonic amplification and even system instability. In addition, passive filters cannot be dynamically adjusted according to the harmonic changes in the power system. Therefore, when the harmonic type changes, its filtering effect will be significantly reduced, limiting its application scope. Compared with passive filters, active power filters have significant advantages. Active filters can quickly track and dynamically compensate harmonic currents, and the dynamic range of the filtered harmonics is relatively wide, making it more effective in coping with the frequently changing harmonics in the system. Due to these advantages, active power filters have been widely used in harmonic treatment and have become effective devices for suppressing harmonics and improving the power quality of the power grid. Since the performance of active power filters depends on the ability of the current control system to quickly track the reference current. Currently, although the complementary sliding mode surface can effectively reduce the tracking error of the system and improve the system tracking performance, compared with the terminal sliding mode, the complementary sliding mode surface cannot achieve finite-time convergence. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an active power filter current tracking control method based on an improved butterfly algorithm, including the following steps: S1. Separate the harmonics of the three-phase grid current through the instantaneous power algorithm to obtain the three-phase harmonic currents; S2. Obtain the output current of the inverter, calculate the difference between the three-phase harmonic currents and the output current of the inverter to obtain the harmonic current tracking error, and construct a fractional-order complementary terminal sliding mode controller based on the harmonic current tracking error; S3. Based on the butterfly algorithm, optimize the butterfly algorithm through the reverse learning strategy, Cauchy mutation strategy, and stochastic concern weight strategy respectively to obtain an improved butterfly optimizer; S4. Optimize the parameters of the fractional-order complementary terminal sliding mode controller through an improved butterfly optimizer, and calculate the harmonic control function based on the sliding mode reaching law; S5. Calculate the control signal through the system dynamics algorithm according to the harmonic control function, and drive the inverter to output the harmonic compensation current.

[0005] Further, step S2 includes the following steps: S201. Based on the harmonic current tracking error, construct a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface respectively; S202. Superimpose the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface to obtain a fractional-order complementary terminal sliding mode surface; S203. Construct a fractional-order complementary terminal sliding mode controller according to the fractional-order complementary terminal sliding mode surface, and the fractional-order complementary terminal sliding mode controller is expressed as: where D is the differential operator, is a constant greater than 0, is the fractional-order, is the fractional-order generalized sliding mode surface function, is the fractional-order compensation sliding mode surface function, is the fractional-order expression of the fractional-order generalized sliding mode surface, is the fractional-order expression of the fractional-order compensation sliding mode surface, is the fractional-order complementary terminal sliding mode surface function.

[0006] Further, the reverse learning strategy is: where, P i,j is the value of the i th butterfly in the j th dimension, is the reverse solution of the ordinary butterfly, B u，j and B l，j are the upper and lower bounds of the j th dimension respectively, q is the elite reverse coefficient, and its value is a random number in (0, 1).

[0007] Further, the Cauchy mutation strategy is: where, P bis the current optimal solution, P nb is the optimal solution after Cauchy mutation, and Cauchy(0, 1) is the Cauchy function.

[0008] Furthermore, the random attention weight strategy is as follows: wherein, is the inertia weight during the z th generation iteration, is the minimum value of the inertia weight constant, is the maximum value of the inertia weight constant, and rand(0, 1) is a random number between [0, 1], representing the random factor.

[0009] Furthermore, the sliding mode reaching law is as follows: wherein, is the derivative of the fractional-order complementary terminal sliding mode surface with respect to time, is the fractional-order complementary terminal sliding mode surface, is the sliding mode surface function corresponding to the k-th phase power grid, is the power function transformation of the sliding mode surface function corresponding to the k-th phase power grid, is the natural logarithm function, and g1, g2, and g3 are constants greater than 0 respectively, is a constant greater than 0 and less than 1, is a constant greater than 0, k is the phase of the three-phase power grid, is a constant greater than 0, tanh() is the hyperbolic tangent function, and asinh() is the inverse hyperbolic sine function.

[0010] Based on the above method, the present invention also provides an active power filter current tracking control system based on an improved butterfly algorithm. This system is implemented based on any one of the above active power filter current tracking control methods using an improved butterfly algorithm, and includes a DC power supply module, a filter capacitor module, and an inverter module that are sequentially connected by signal. This system further includes: A DC-side voltage fractional-order PI control module for controlling the output voltage of the DC power supply module through a fractional-order PI control algorithm; A harmonic separation module for separating harmonics from the grid current through an instantaneous power algorithm to obtain three-phase harmonic currents; A filter capacitor module for preliminarily filtering the three-phase harmonic currents; A current tracking control module for calculating the harmonic current tracking error based on the three-phase harmonic currents and the inverter output current, and calculating a harmonic control function based on the harmonic current tracking error through a fractional-order complementary terminal sliding mode control algorithm; The PWM driving module is used to calculate a harmonic current control signal through a system dynamics algorithm according to a harmonic control function, and drive an inverter module to perform tracking control on the current.

[0011] Furthermore, the current tracking control module further includes: A fractional-order generalized integral sliding mode surface unit, which is used to track the harmonic current tracking error by constructing a fractional-order generalized integral sliding mode surface; A fractional-order complementary sliding mode surface unit, which is used to construct a fractional-order complementary terminal sliding mode surface by constructing a fractional-order complementary sliding mode surface and superposing it with the fractional-order generalized integral sliding mode surface; A robust switching unit, which is used to improve the robustness of the fractional-order complementary terminal sliding mode surface through a nonlinear reaching law; A fractional-order complementary terminal sliding mode control unit, which is used to calculate a harmonic control function by using a Lyapunov function as a stability function according to the fractional-order complementary terminal sliding mode surface and a sliding mode reaching law; An improved butterfly algorithm optimizer, which is used to optimize the parameters of the fractional-order complementary terminal sliding mode surface through a reverse learning strategy, a Cauchy mutation strategy and a random inertia weight strategy.

[0012] A computer device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements an active power filter current tracking control method based on an improved butterfly algorithm as described in any one of the above.

[0013] A storage medium stores a computer program thereon. When the computer program is executed by a processor, it implements an active power filter current tracking control method based on an improved butterfly algorithm as described in any one of the above.

[0014] The beneficial effects of the present invention are that for the active power filter current tracking control method and system based on an improved butterfly algorithm, the parameters and orders of the controller are optimized through an improved butterfly parameter optimizer. A fractional-order complementary terminal sliding mode surface is designed to improve the system tracking performance and enable the system to converge within a finite time. At the same time, the traditional butterfly optimization algorithm is improved by introducing a reverse learning strategy, a Cauchy mutation strategy and a random inertia weight strategy, which improves the convergence accuracy and speed of the optimizer. The active power filter adopting fractional-order complementary terminal sliding mode control can not only well eliminate the harmonics generated by nonlinear loads, but also meet the high requirements for stability. Description of the Drawings

[0015] Figure 1 The schematic flowchart of an active power filter current tracking control method based on an improved butterfly algorithm according to an embodiment of the present invention.

[0016] Figure 2 、Schematic diagram of the structure of an active power filter current tracking control system based on an improved butterfly algorithm according to an embodiment of the present invention.

[0017] Figure 3 、Flow chart of the calculation of the improved butterfly algorithm according to an embodiment of the present invention.

[0018] Figure 4 、Comparison diagram before and after the improvement of the butterfly optimization algorithm according to an embodiment of the present invention.

[0019] Figure 5 、Waveform diagram of the three-phase current before filtering according to an embodiment of the present invention.

[0020] Figure 6 、Spectrum diagram of the three-phase current before filtering according to an embodiment of the present invention.

[0021] Figure 7 、Waveform diagram of the three-phase current after filtering according to an embodiment of the present invention.

[0022] Figure 8 、Spectrum diagram of the three-phase current after filtering according to an embodiment of the present invention.

[0023] Figure 9 、Schematic diagram of the structure of a terminal device for active power filter current tracking control based on an improved butterfly algorithm according to an embodiment of the present invention.

[0024] Figure 10 、Schematic diagram of the structure of a computer-readable storage medium for an active power filter current tracking control method based on an improved butterfly algorithm according to an embodiment of the present invention.

[0025] In the figure, 200 - terminal device, 210 - memory, 211 - RAM, 212 - cache memory, 213 - ROM, 214 - program / utilities, 215 - program modules, 220 - processor, 230 - bus, 240 - external device, 250 - I / O interface, 260 - network adapter, 300 - program product. Detailed implementation manners

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings herein can be arranged and designed in various different configurations.

[0027] Embodiment 1: As Figure 1As shown in the figure, Embodiment 1 of the present invention provides a current tracking control method for an active power filter based on an improved butterfly algorithm, including the following steps: Specifically, before implementing step S1, the following specific steps described in step S0 should also be implemented: Connect the three output terminals of the inverter to the three-phase power bus through inductors connected in series L and resistors r respectively, and connect the front end of the inverter to the DC power supply through a filter capacitor C ; S1. Separate the harmonic components from the three-phase grid current through the instantaneous power algorithm to obtain the three-phase harmonic currents; Specifically, the harmonic separation is realized through the ip-iq algorithm in the instantaneous power theory.

[0028] S2. Obtain the output current of the inverter, calculate the difference between the three-phase harmonic currents and the output current of the inverter to obtain the harmonic current tracking error, and construct a fractional-order complementary terminal sliding mode controller based on the harmonic current tracking error; Furthermore, step S2 includes the following steps: S201. Construct a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface respectively based on the harmonic current tracking error; S202. Superimpose the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface to obtain a fractional-order complementary terminal sliding mode surface; S203. Construct a fractional-order complementary terminal sliding mode controller according to the fractional-order complementary terminal sliding mode surface. The fractional-order complementary terminal sliding mode controller is expressed as: where D is the differential operator, is a constant greater than 0, is the fractional order, is the fractional-order generalized sliding mode surface function, is the fractional-order compensation sliding mode surface function, is the fractional-order expression of the fractional-order generalized sliding mode surface, is the fractional-order expression of the fractional-order compensation sliding mode surface, is the fractional-order complementary terminal sliding mode surface function.

[0029] Specifically, the implementation principle flow of each sub-step in the above embodiment is as follows: In step S201, first construct a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface respectively based on the harmonic current tracking error. The fractional-order generalized integral sliding mode surface is expressed as: where is the harmonic current tracking error, is the fractional-order generalized integral sliding mode surface function, D is the differential operator, is the fractional order, is the order of the fractional-order differential operator, is a constant greater than 0, and n is the system order; The fractional-order complementary sliding mode surface is expressed as: where, is the fractional-order complementary sliding mode surface function; The harmonic current tracking error is expressed as: where, is the harmonic current function related to time t , is the three-phase current function of the inverter output connected to the three-phase bus, k is the phase of the three-phase power grid, k = a, b, c, respectively representing a phase power grid 、b phase power grid and c phase power grid.

[0030] In step S202, the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface are superimposed to obtain a fractional-order complementary terminal sliding mode surface, which is expressed as: where, is the fractional-order complementary terminal sliding mode surface function, δ is a constant greater than 0, is the harmonic current error of the In step S203, the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface are respectively differentiated, and their calculation formulas are: According to the differentiated fractional-order generalized integral sliding mode surface and fractional-order complementary sliding mode surface, a fractional-order complementary terminal sliding mode controller is constructed.

[0031] S3. Based on the butterfly algorithm, the butterfly algorithm is optimized respectively through the reverse learning strategy, Cauchy mutation strategy and stochastic concern weight strategy to obtain an improved butterfly optimizer. The flow schematic diagram of the butterfly optimization algorithm is as Figure 3 shown; Specifically, the reverse learning strategy is expressed as: Among them, P i,j is the value of the i th butterfly in the j dimension, is the reverse solution of the ordinary butterfly, B u，j and B l，j are the upper and lower bounds of the j th dimension respectively, q is the elite reverse coefficient, and its value is a random number in (0, 1); Specifically, the Cauchy mutation strategy is: Among them, P b is the current optimal solution, P nb is the optimal solution after Cauchy mutation, and Cauchy(0, 1) is the Cauchy function; Specifically, the random concern weight strategy is: Among them, is the inertia weight during the Z th generation iteration, is the minimum value of the inertia weight constant, is the maximum value of the inertia weight constant, and rand(0, 1) is a random number between [0, 1], representing the random factor, which is usually regenerated in each iteration.

[0032] S4. Optimize the parameters of the fractional complementary terminal sliding mode controller through the improved butterfly optimizer, and calculate the harmonic control function based on the sliding mode reaching law; Specifically, the sliding mode reaching law is: Among them, is the derivative of the fractional complementary terminal sliding mode surface with respect to time, that is, the time change rate of the fractional complementary terminal sliding mode surface, is the fractional complementary terminal sliding mode surface, is the sliding mode surface function corresponding to the k - th phase power grid, is the power function transformation of the sliding mode surface function corresponding to the k - th phase power grid, is the natural logarithm function, is a constant greater than 0, used to adjust the response speed and reaching speed of the fractional complementary terminal sliding mode controller, and g1, g2, g3 are constants greater than 0 respectively, is a constant greater than 0 and less than 1, and k is the phase of the three-phase power grid. , is a constant greater than 0, tanh() is the hyperbolic tangent function, and asinh() is the inverse hyperbolic sine function. Specifically, the harmonic control function is: where, represents the DC-side voltage, represents the inductor, represents the resistor, represents the control gain, represents the harmonic current derivative of, is the harmonic current error of power, D represents the differential operator, ɑ represents the fractional order, and g1, g2, and g3 are constants greater than 0 respectively. represents the three-phase power supply voltage, is a constant greater than 0 and less than 1, is a constant greater than 0.

[0033] In this embodiment, the Lyapunov function is selected as the stability function for the design of the sliding mode control strategy, that is: where, is the square of the fractional-order generalized sliding mode surface, is the square of the fractional-order compensation sliding mode surface, is the generalized energy function.

[0034] Then, the derivative of the Lyapunov function is taken, and the fractional-order generalized integral sliding mode surface, fractional-order complementary sliding mode surface, fractional-order complementary terminal sliding mode controller, sliding mode reaching law, and harmonic control function after differentiation are substituted respectively, and we can get: where, represents the generalized energy function, represents the DC-side voltage, represents the harmonic current error derivative of, represents the harmonic current derivative of, is a constant greater than 0 and less than 1; Thus, the designed controller satisfies the Lyapunov stability condition, and therefore, the system is asymptotically stable.

[0035] S5. Calculate the control signal through the system dynamics algorithm according to the harmonic control function, and drive the inverter to output the harmonic compensation current.

[0036] Specifically, the implementation principle process of step S5 in the above embodiment is as follows: Based on the three-phase power supply voltage , establish the mathematical model of the active power filter according to the circuit principle and Kirchhoff's theorem as: Among them, represents the differential operator, respectively represent abc the three-phase power supply voltage, represents the DC-side voltage, respectively represent the three-phase currents (as compensation currents) output by the inverter and connected to the three-phase busbars, respectively represent the control condition functions of the three-phase power supply, represents the inductor, represents the resistor.

[0037] Assume that the three-phase grid voltage is balanced, so it can be obtained that: Among them, is the three-phase voltage reference ground point, respectively represent the line voltages between the voltages at points a, b, and c on the AC side of the three-phase inverter and the voltage at point N; represents the line voltage between the voltage at point N and the reference ground point O, is the switching function of the inverter IGBT (Insulated Gate Bipolar Transistor), indicating the on-off state of the main circuit switching device, and is specifically defined as: When is 1, the upper bridge arm conducts and the lower bridge arm turns off; when is 0, the upper bridge arm turns off and the lower bridge arm conducts.

[0038] Then the dynamic model of the active power filter is obtained as: Among them, is the reciprocal of, specifically, the control condition function is expressed as: Among them, is the switching function of the inverter IGBT (Insulated Gate Bipolar Transistor), and the control condition function Sk The non - linear matrix expression is as follows: Wherein, respectively represent abc the control condition functions of the three - phase power supply, respectively represent the switching functions of the inverter IGBT (Insulated Gate Bipolar Transistor) corresponding to abc the three - phase power supply.

[0039] To verify the simulation test of the improved and original butterfly optimization algorithms using the standard test function Sphere, the expression of the Sphere function is as follows: Wherein, is the standard test function Sphere, is the test variable, is the square of the nth test variable.

[0040] As Figure 4 shown, the convergence speed of the improved butterfly optimization algorithm is significantly better than that of the original butterfly optimization algorithm. At the same time, the minimum value obtained by the improved butterfly optimization algorithm is smaller than that obtained by the original one. As Figures 5 - 8 shown, this embodiment respectively outputs the waveform diagrams and spectrograms of the three - phase current before and after filtering. This shows that the improved butterfly optimization algorithm has a faster convergence speed and higher convergence accuracy. To further verify the superiority of the present invention, the control method proposed in the present invention (IBOA - FOCTSMC) is respectively compared with terminal sliding mode control (TSMC), complementary sliding mode control (CSMC), complementary terminal sliding mode control (CTSMC), and butterfly - optimization - based fractional - order complementary terminal sliding mode control (BOA - FOCTSMC). By building the corresponding simulation model and conducting simulations, the absolute error of a - phase current tracking and the filtering effect are obtained, as shown in Table 1.

[0041] Table 1 Schematic table of the absolute error of current tracking and filtering effect It can be seen from Table 1 above that for the APF using the control strategy proposed in the present invention, its harmonic suppression effect (i.e., THD) is better than the other four control strategies.

[0042] In summary, the control strategy proposed in the present invention can make the current tracking accuracy of the active power filter higher and the filtering effect better, thus having a stronger harmonic control capability.

[0043] Example 2 like Figure 2 As shown, on the basis of Example 1, Example 2 of the present invention proposes an active power filter current tracking control system based on an improved butterfly algorithm implemented based on an active power filter current tracking control method based on an improved butterfly algorithm.

[0044] Specifically, the system includes a DC power supply module, a filter capacitor module and an inverter module which are sequentially connected, and the three output ends of the inverter module are connected in series through an inductor L and resistor r Connecting to the three-phase power bus, the system also includes: A DC side voltage fractional-order PI control module, used to control the output voltage of the DC power supply module through a fractional-order PI control algorithm; The harmonic separation module is used to perform harmonic separation on the grid current through an instantaneous power algorithm to obtain three-phase harmonic current; The filter capacitor module is used to perform preliminary filtering on the three harmonic currents; A current tracking control module is used to calculate a harmonic current tracking error based on the three-phase harmonic current and the inverter output current, and based on the harmonic current tracking error, calculate a harmonic control function through a fractional-order complementary terminal sliding mode control algorithm; The PWM drive module is used to obtain the harmonic current control signal according to the harmonic control function through the system dynamics algorithm, and drive the inverter module to track and control the current.

[0045] Specifically, the current tracking control module also includes: A fractional-order generalized integral sliding surface unit is used to track the harmonic current tracking error by constructing a fractional-order generalized integral sliding surface; A fractional-order complementary sliding surface unit is used to construct a fractional-order complementary sliding surface and superimpose it with the fractional-order generalized integral sliding surface to construct a fractional-order complementary terminal sliding surface; A robust switching unit, used for improving the robustness of the fractional-order complementary terminal sliding mode surface through a nonlinear reaching law; A fractional-order complementary terminal sliding mode control unit is used to calculate a harmonic control function based on the fractional-order complementary terminal sliding mode surface and the sliding mode reaching law by using a Lyapunov function as a stability function; The improved butterfly algorithm optimizer is used to optimize the parameters of the fractional-order complementary terminal sliding surface through reverse learning strategy, Cauchy mutation strategy and random inertia weight strategy.

[0046] Specifically, the working process of the system is as follows: First, through the DC-side voltage fractional-order PI control module, the reference voltage is output through the fractional-order PI control algorithm to ensure that during the subsequent harmonic control process, the interference caused by the controller current to harmonic separation is avoided; Then, through the harmonic separation module, the three-phase harmonic currents are separated from the three-phase grid currents by using the instantaneous power algorithm, and are preliminarily filtered through the filter capacitor module; Next, through the current tracking control module, the harmonic current tracking error is calculated based on the three-phase harmonic currents and the inverter output current, and based on the harmonic current tracking error, the harmonic control function is calculated through the fractional-order complementary terminal sliding mode control algorithm; Subsequently, through the PWM driving module, according to the harmonic control function, the harmonic current control signal is calculated through the system dynamics algorithm, and the inverter module is driven to achieve the tracking control of the three-phase current.

[0047] Embodiment 3 As Figure 9 shown, on the basis of Embodiment 1, this Embodiment 3 proposes a terminal device for the current tracking control method of an active power filter based on an improved butterfly algorithm. The terminal device 200 includes at least one memory 210, at least one processor 220, and a bus 230 connecting different platform systems.

[0048] The memory 210 may include a readable medium in the form of volatile memory, such as RAM 211 and / or cache memory 212, and may further include ROM 213.

[0049] Among them, the memory 210 also stores a computer program, which can be executed by the processor 220, so that the processor 220 executes any one of the above-mentioned methods for the current tracking control method of an active power filter based on an improved butterfly algorithm in the embodiments of the present application. The specific implementation manner is consistent with the implementation manners and the achieved technical effects recorded in the embodiments of the above method, and some contents will not be elaborated. The memory 210 may further include a program / utilities 214 having a set (at least one) of program modules 215. Such program modules include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include the implementation of a network environment.

[0050] Correspondingly, the processor 220 can execute the above computer program and can also execute the program / utilities 214.

[0051] The bus 230 may represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of the various bus structures.

[0052] The terminal device 200 can also communicate with one or more external devices 240 such as a keyboard, a pointing device, a Bluetooth device, etc., and can also communicate with one or more devices capable of interacting with the terminal device 200, and / or communicate with any device (such as a router, a modem, etc.) that enables the terminal device 200 to communicate with one or more other computing devices. This communication can be carried out through the I / O interface 250. Moreover, the terminal device 200 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through the network adapter 260. The network adapter 260 can communicate with other modules of the terminal device 200 through the bus 230. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in combination with the terminal device 200, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms, etc.

[0053] Embodiment 4 As Figure 10 shown, on the basis of Embodiment 1, this embodiment proposes a computer-readable storage medium for an active power filter current tracking control method based on an improved butterfly algorithm. Instructions are stored on the computer-readable storage medium, and when the instructions are executed by a processor, an active power filter current tracking control method based on any of the above is implemented. Its specific implementation manner is consistent with the implementation manner and the achieved technical effects described in the embodiments of the above method, and some content will not be elaborated again.

[0054] Figure 10Fig. 0 shows a program product 300 provided by this embodiment for implementing the above method. It may be a portable compact disc read-only memory (CD-ROM), include program code, and can run on a terminal device, such as a personal computer. However, the program product 300 of the present invention is not limited thereto. In this embodiment, the readable storage medium may be any tangible medium that contains or stores a program, and this program can be used by or in conjunction with an instruction execution system, apparatus, or device. The program product 300 may adopt any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may, for example, but not be limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disc, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0055] The computer-readable storage medium may include a data signal propagated in a baseband or as part of a carrier wave, in which the readable program code is carried. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium may also be any readable medium other than the readable storage medium, and this readable medium can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium can be transmitted by any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above. The program code for performing the operations of the present invention can be written in any combination of one or more programming languages. The programming languages include object-oriented programming languages such as Java, C++, etc., and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, executed as an independent software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, by using an Internet service provider to connect through the Internet).

[0056] The present invention is described from the perspectives of purpose of use, efficacy, progressiveness, and novelty. It has practical progressiveness and meets the functional enhancement and use requirements emphasized by the Patent Law. The above description and drawings of this application are only preferred embodiments of this application and do not limit this application. Therefore, all those that are similar or identical to the structure, device, features, etc. of this application, that is, all equivalent replacements or modifications made according to the scope of the patent application of this application, shall fall within the scope of protection of the patent application of this application.

[0057] The specific implementation manners described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A current tracking control method for an active power filter based on an improved butterfly algorithm, characterized in that It includes the following steps: S1. Perform harmonic separation on the three-phase grid current through the instantaneous power algorithm to obtain three-phase harmonic currents; S2. Obtain the inverter output current, calculate the difference between the three-phase harmonic currents and the inverter output current to obtain the harmonic current tracking error, and based on the harmonic current tracking error, construct a fractional-order complementary terminal sliding mode controller; S3. Based on the butterfly algorithm, optimize the butterfly algorithm through the reverse learning strategy, Cauchy mutation strategy, and stochastic inertia weight strategy respectively to obtain an improved butterfly optimizer; S4. Optimize the parameters of the fractional-order complementary terminal sliding mode controller through the improved butterfly optimizer, and calculate the harmonic control function based on the sliding mode reaching law; S5. According to the harmonic control function, calculate the control signal through the system dynamics algorithm to drive the inverter to output harmonic compensation current.

2. The current tracking control method of an active power filter based on an improved butterfly algorithm according to claim 1, characterized in that Step S2 includes the following steps: S201. Based on the harmonic current tracking error, construct a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface respectively; S202. Superimpose the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface to obtain a fractional-order complementary terminal sliding mode surface; S203. Construct a fractional-order complementary terminal sliding mode controller according to the fractional-order complementary terminal sliding mode surface, and the fractional-order complementary terminal sliding mode controller is expressed as: where D is the differential operator, is a constant greater than 0, is the fractional order, is the fractional order generalized sliding mode surface function, is the fractional order compensation sliding mode surface function, is the fractional order expression of the fractional order generalized sliding mode surface, is the fractional order expression of the fractional order compensation sliding mode surface, is the fractional order complementary terminal sliding mode surface function.

3. A current tracking control method for an active power filter based on an improved butterfly algorithm according to claim 1, characterized in that, The reverse learning strategy is: in, For the i A butterfly in the j The value of the dimension, is the reverse solution of the ordinary butterfly, and Respectively j The upper and lower bounds of dimension, q is the elite reverse coefficient, whose value is a random number in (0, 1).

4. A current tracking control method for an active power filter based on an improved butterfly algorithm according to claim 1, characterized in that The Cauchy mutation strategy is: Among them, is the current optimal solution, is the optimal solution after Cauchy mutation, is the Cauchy function.

5. A current tracking control method for an active power filter based on an improved butterfly algorithm according to claim 1, characterized in that The stochastic inertia weight strategy is: Among them, is the inertial weight during the th generation of iteration, is the minimum value of the inertial weight constant, is the maximum value of the inertial weight constant, and rand(0, 1) is a random number between [0, 1], representing the random factor.

6. The current tracking control method of an active power filter based on an improved butterfly algorithm according to claim 1, characterized in that The sliding mode reaching law is: Among them, is the derivative of the fractional-order complementary terminal sliding mode surface with respect to time, is the fractional-order complementary terminal sliding mode surface, is the sliding mode surface function corresponding to the k-th phase power grid, is the power function transformation of the sliding mode surface function corresponding to the k-th phase power grid, is the natural logarithm function, and g1, g2, and g3 are constants greater than 0 respectively, is a constant greater than 0 and less than 1, is a constant greater than 0, k is the phase of the three-phase power grid, is a constant greater than 0, tanh() is the hyperbolic tangent function, and asinh() is the inverse hyperbolic sine function.

7. An active power filter current tracking control system based on an improved butterfly algorithm, which is implemented based on the active power filter current tracking control method described in any one of claims 1-6, and includes a DC power supply module, a filter capacitor module, and an inverter module that are sequentially connected by signal. It is characterized in that, This system further includes: A DC-side voltage fractional-order PI control module for controlling the output voltage of the DC power supply module through the fractional-order PI control algorithm; A harmonic separation module for performing harmonic separation on the grid current through the instantaneous power algorithm to obtain three-phase harmonic currents; A filter capacitor module for preliminarily filtering the three-phase harmonic currents; A current tracking control module for calculating the harmonic current tracking error based on the three-phase harmonic currents and the inverter output current, and calculating the harmonic control function based on the harmonic current tracking error through the fractional-order complementary terminal sliding mode control algorithm; A PWM driving module for calculating the harmonic current control signal through the system dynamics algorithm according to the harmonic control function and driving the inverter module to perform current tracking control.

8. An active power filter current tracking control system based on an improved butterfly algorithm according to claim 7, characterized in that, The current tracking control module further includes: A fractional-order generalized integral sliding mode surface unit for tracking the harmonic current tracking error by constructing a fractional-order generalized integral sliding mode surface; A fractional-order complementary sliding mode surface unit for constructing a fractional-order complementary sliding mode surface and superimposing it with the fractional-order generalized integral sliding mode surface to construct a fractional-order complementary terminal sliding mode surface; A robust switching unit for improving the robustness of the fractional-order complementary terminal sliding mode surface through a nonlinear reaching law; A fractional-order complementary terminal sliding mode control unit for calculating the harmonic control function based on the fractional-order complementary terminal sliding mode surface and the sliding mode reaching law by using the Lyapunov function as the stability function; An improved butterfly algorithm optimizer for optimizing the parameters of the fractional-order complementary terminal sliding mode surface through the reverse learning strategy, Cauchy mutation strategy, and stochastic inertia weight strategy.

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