A current tracking control method and system for active power filter based on improved butterfly algorithm

Abstract

The present invention relates to the technical field of harmonic optimization for DC converter stations, and in particular to a current tracking control method and system for an active power filter based on an improved butterfly algorithm. The method calculates the harmonic current tracking error and constructs a fractional-order complementary terminal sliding mode controller. The butterfly algorithm is optimized using a reverse learning strategy, a Cauchy mutation strategy, and a randomized care weight strategy. The fractional-order complementary terminal sliding mode controller is optimized using an improved butterfly optimizer to obtain a harmonic control function. A control signal is then calculated based on the harmonic control function to drive an inverter to output a harmonic compensation current. The fractional-order complementary terminal sliding mode surface is used to improve system tracking performance, allowing the system to converge within a finite time. Furthermore, by improving the traditional butterfly optimization algorithm, the convergence accuracy and speed of the optimizer are improved. This enables the active power filter to effectively eliminate harmonics generated by nonlinear loads while also ensuring stability.

Description

Technical Field

[0001] The present invention relates to the technical field of harmonic optimization of a DC converter station, and in particular 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 core components of power systems, play a vital role. However, power electronic equipment (such as thyristors and IGBTs) within these stations generate significant harmonics during operation. These harmonics severely impact power quality, equipment safety, and communication systems. Specifically, harmonics distort voltage and current waveforms, impacting power system stability. They also cause excessive heat generation and losses in equipment such as transformers and cables, shortening their service life. Furthermore, harmonics can cause electromagnetic interference to adjacent communication lines, impacting the normal operation of communication systems. Therefore, harmonic control in DC converter stations is of great theoretical and practical significance.

[0003] Currently, there are two main methods for harmonic suppression in DC converter stations: passive filtering and active filtering. Passive filters use an LC circuit consisting of inductors and capacitors to filter harmonics of specific frequencies. Their advantages include simple structure, low cost, and high reliability, but they also have disadvantages such as large size, susceptibility to system resonance, and significant influence of system impedance on filtering effectiveness. For low-order harmonic control, single-tuned passive filters are commonly used due to their low cost and ability to effectively control specific low-order harmonics. For higher-order harmonic control, high-pass passive filters are more suitable. However, passive filters are limited by their single compensation characteristic, filtering only harmonics of a specific frequency and struggling to cope with complex harmonic environments. To overcome this limitation, double-tuned filters have been proposed and widely used. Double-tuned filters can simultaneously filter out two specific harmonic frequencies, offering higher filtering efficiency and suitability for applications with complex harmonic content while also saving installation space. However, double-tuned filters also have certain drawbacks. For example, when system impedance changes, they can resonate with the system, leading to harmonic amplification and even system instability. Furthermore, passive filters cannot dynamically adjust to harmonic changes in the power system. Therefore, their filtering effectiveness is significantly reduced when the harmonic type changes, limiting their scope of application. Active power filters offer significant advantages over passive filters. Active filters can quickly track and dynamically compensate for harmonic currents, and they filter harmonics over a wide dynamic range, enabling them to more effectively cope with frequently changing harmonics in the system. Due to these advantages, active power filters have been widely used in harmonic control, becoming effective devices for suppressing harmonics and improving grid power quality. The performance of active power filters depends on the ability of the current control system to quickly track the command current. Currently, while complementary sliding modes can effectively reduce system tracking errors and improve system tracking performance, they cannot achieve finite-time convergence compared to terminal sliding modes. 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, comprising the following steps:

[0005] S1. Perform harmonic separation on the three-phase grid current using an instantaneous power algorithm to obtain three-phase harmonic current;

[0006] S2. Obtain the inverter output current, calculate the difference between the three-phase harmonic current and the inverter output current, obtain the harmonic current tracking error, and construct a fractional-order complementary terminal sliding mode controller based on the harmonic current tracking error;

[0007] S3. Based on the butterfly algorithm, the butterfly algorithm is optimized using the reverse learning strategy, the Cauchy mutation strategy, and the random care weight strategy to obtain an improved butterfly optimizer;

[0008] S4. Parameter optimization of the fractional-order complementary terminal sliding mode controller is performed by improving the butterfly optimizer, and a harmonic control function is calculated based on the sliding mode reaching law;

[0009] S5. According to the harmonic control function, a control signal is calculated by a system dynamics algorithm to drive the inverter to output a harmonic compensation current.

[0010] Furthermore, step S2 includes the following steps:

[0011] S201. Based on the harmonic current tracking error, a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface are constructed respectively;

[0012] S202. Superimposing the fractional-order generalized integral sliding surface and the fractional-order complementary sliding surface to obtain a fractional-order complementary terminal sliding surface;

[0013] S203. Construct a fractional-order complementary terminal sliding mode controller based on the fractional-order complementary terminal sliding mode surface. The fractional-order complementary terminal sliding mode controller is expressed as:

[0014]

[0015] Where D is the differential operator, ε is a constant greater than 0, ɑ is the fractional order, S fgk (t) is the fractional-order generalized integral sliding surface function, S fck (t) is the fractional-order complementary sliding surface function, D ɑ S fgk (t) is the fractional order expression of the fractional order generalized integral sliding mode surface, D ɑ S fck (t) is the fractional order expression of the fractional order complementary sliding mode surface, S fk (t) is the fractional-order complementary terminal sliding mode surface function.

[0016] Furthermore, the reverse learning strategy is:

[0017]

[0018]

[0019]

[0020] Among them, 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, and q is the elite reverse coefficient, which is a random number in (0, 1).

[0021] Furthermore, the Cauchy mutation strategy is:

[0022]

[0023] 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.

[0024] Furthermore, the random attention weight strategy is:

[0025]

[0026] in, is the inertia weight at the z-th iteration, is the minimum value of the inertia weight constant, is the maximum value of the inertia weight constant, rand(0,1) is a random number between [0, 1], representing the random factor.

[0027] Furthermore, the sliding mode reaching law is:

[0028]

[0029] in, is the time derivative of the fractional-order complementary terminal sliding mode surface function, is the fractional-order complementary terminal sliding mode surface function, 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 a natural logarithmic function, g1, g2, and g3 are constants greater than 0, 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.

[0030] Based on the above method, the present invention also provides an active power filter current tracking control system based on an improved butterfly algorithm. The system is implemented based on any one of the above active power filter current tracking control methods based on the improved butterfly algorithm, and includes a DC power supply module, a filter capacitor module, and an inverter module that are sequentially signal-connected. The system also includes:

[0031] A DC side voltage fractional-order PI control module, configured to control the output voltage of the DC power supply module using a fractional-order PI control algorithm;

[0032] Harmonic separation module, used to perform harmonic separation on the grid current through instantaneous power algorithm to obtain three-phase harmonic current;

[0033] Filter capacitor module, used for preliminary filtering of three-phase harmonic current;

[0034] The current tracking control module is used to calculate the harmonic current tracking error based on the three-phase harmonic current and the inverter output current, and to calculate the harmonic control function based on the harmonic current tracking error using a fractional-order complementary terminal sliding mode control algorithm;

[0035] 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.

[0036] Furthermore, the current tracking control module further includes:

[0037] A fractional-order generalized integral sliding mode surface unit is used to track the harmonic current tracking error by constructing a fractional-order generalized integral sliding mode surface;

[0038] 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;

[0039] A robust switching unit, configured to improve the robustness of the fractional-order complementary terminal sliding mode surface through a nonlinear reaching law;

[0040] 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, using the Lyapunov function as a stability function;

[0041] An improved butterfly algorithm optimizer is used to optimize the parameters of the fractional-order complementary terminal sliding surface through a reverse learning strategy, a Cauchy mutation strategy, and a random inertia weight strategy.

[0042] A computer device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for current tracking control of an active power filter based on an improved butterfly algorithm as described above is implemented.

[0043] A storage medium stores a computer program thereon, wherein when the computer program is executed by a processor, the computer program implements any one of the above-mentioned methods for current tracking control of an active power filter based on an improved butterfly algorithm.

[0044] The beneficial effects of the present invention are that the active power filter current tracking control method and system based on the improved butterfly algorithm optimizes the controller parameters and orders by improving the butterfly parameter optimizer. A fractional-order complementary terminal sliding mode surface is designed to improve the system tracking performance and allow 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, thereby improving the convergence accuracy and speed of the optimizer. The active power filter using fractional-order complementary terminal sliding mode control can not only effectively eliminate the harmonics generated by the nonlinear load, but also meet higher stability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 , a flow chart of a current tracking control method for an active power filter based on an improved butterfly algorithm according to an embodiment of the present invention.

[0046] Figure 2 , a structural diagram of an active power filter current tracking control system based on an improved butterfly algorithm in an embodiment of the present invention.

[0047] Figure 3 , calculation flow chart of the improved butterfly algorithm of an embodiment of the present invention.

[0048] Figure 4 , a comparison chart of the butterfly optimization algorithm before and after improvement according to an embodiment of the present invention.

[0049] Figure 5 , waveform diagram of the three-phase current before filtering according to an embodiment of the present invention.

[0050] Figure 6 , spectrum diagram of the three-phase current before filtering according to an embodiment of the present invention.

[0051] Figure 7 , waveform diagram of the three-phase current after filtering according to an embodiment of the present invention.

[0052] Figure 8 , spectrum diagram of the filtered three-phase current according to an embodiment of the present invention.

[0053] Figure 9 , a schematic diagram of the terminal device structure of an active power filter current tracking control based on an improved butterfly algorithm in an embodiment of the present invention.

[0054] Figure 10 , a schematic diagram of the computer-readable storage medium structure of an active power filter current tracking control method based on an improved butterfly algorithm in an embodiment of the present invention.

[0055] In the figure, 200 - terminal device, 210 - memory, 211 - RAM, 212 - cache memory, 213 - ROM, 214 - program / utility, 215 - program module, 220 - processor, 230 - bus, 240 - external device, 250 - I / O interface, 260 - network adapter, 300 - program product. DETAILED DESCRIPTION

[0056] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in various different configurations.

[0057] Example 1:

[0058] like Figure 1 As shown, embodiment 1 of the present invention provides an active power filter current tracking control method based on an improved butterfly algorithm, comprising the following steps:

[0059] Specifically, before implementing step S1, the specific steps described in step S0 should also be implemented:

[0060] The three output terminals of the inverter are connected to the three-phase power bus through the series inductor L and resistor r, and the front end of the inverter is connected to the DC power supply through the filter capacitor C;

[0061] S1. Perform harmonic separation on the three-phase grid current using an instantaneous power algorithm to obtain three-phase harmonic current;

[0062] Specifically, the harmonic separation is achieved through the ip-iq algorithm in instantaneous power theory.

[0063] S2. Obtain the inverter output current, calculate the difference between the three-phase harmonic current and the inverter output current, obtain the harmonic current tracking error, and construct a fractional-order complementary terminal sliding mode controller based on the harmonic current tracking error;

[0064] Furthermore, step S2 includes the following steps:

[0065] S201. Based on the harmonic current tracking error, a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface are constructed respectively;

[0066] S202. Superimposing the fractional-order generalized integral sliding surface and the fractional-order complementary sliding surface to obtain a fractional-order complementary terminal sliding surface;

[0067] S203. Construct a fractional-order complementary terminal sliding mode controller based on the fractional-order complementary terminal sliding mode surface. The fractional-order complementary terminal sliding mode controller is expressed as:

[0068]

[0069] Where D is the differential operator, ε is a constant greater than 0, ɑ is the fractional order, S fgk (t) is the fractional order generalized integral sliding surface function, S fck (t) is the fractional-order complementary sliding surface function, D ɑ S fgk (t) is the fractional order expression of the fractional order generalized integral sliding mode surface, D ɑ S fck (t) is the fractional order expression of the fractional order complementary sliding mode surface, S fk (t) is the fractional-order complementary terminal sliding mode surface function.

[0070] Specifically, the implementation principle flow of each sub-step in the above embodiment is as follows:

[0071] In step S201, a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface are constructed based on the harmonic current tracking error. The fractional-order generalized integral sliding mode surface is expressed as:

[0072]

[0073] in, is the harmonic current tracking error, is the fractional-order generalized integral sliding surface function, D is the differential operator, ɑ is the fractional order, D ɑ The order is The fractional differential operator of , ε is a constant greater than 0, and n is the system order;

[0074] The fractional-order complementary sliding mode surface is expressed as:

[0075]

[0076] in, is the fractional-order complementary sliding surface function;

[0077] The harmonic current tracking error Expressed as:

[0078]

[0079] in, is the harmonic current function related to time t, is the three-phase current function connected to the three-phase bus output by the inverter, k is the phase of the three-phase grid, k=a,b,c, respectively represents the a-phase grid, b-phase grid and c-phase grid.

[0080] 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:

[0081]

[0082] in, is the fractional-order complementary terminal sliding surface function, δ is a constant greater than 0, is the harmonic current error of power;

[0083] In step S203, the fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface are derived respectively, and the calculation formula is:

[0084]

[0085]

[0086] According to the derived fractional-order generalized integral sliding mode surface and the fractional-order complementary sliding mode surface, a fractional-order complementary terminal sliding mode controller is constructed.

[0087] S3. Based on the butterfly algorithm, the butterfly algorithm is optimized by reverse learning strategy, Cauchy mutation strategy and random care weight strategy respectively to obtain an improved butterfly optimizer. The flowchart of the butterfly optimization algorithm is as follows: Figure 3 As shown;

[0088] Specifically, the reverse learning strategy is expressed as:

[0089]

[0090]

[0091]

[0092] Among them, 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, and q is the elite reverse coefficient, which is a random number in (0, 1);

[0093] Specifically, the Cauchy mutation strategy is:

[0094]

[0095] Among them, P b is the current optimal solution, P nb is the optimal solution after Cauchy mutation, Cauchy(0,1) is the Cauchy function;

[0096] Specifically, the random attention weight strategy is:

[0097]

[0098] in, is the inertia weight at the Zth iteration, is the minimum value of the inertia weight constant, is the maximum value of the inertia weight constant, rand(0,1) is a random number between [0, 1], representing a random factor, which is usually regenerated in each iteration.

[0099] S4. Parameter optimization of the fractional-order complementary terminal sliding mode controller is performed by improving the butterfly optimizer, and a harmonic control function is calculated based on the sliding mode reaching law;

[0100] Specifically, the sliding mode reaching law is:

[0101]

[0102] in, is the time derivative of the fractional-order complementary terminal sliding mode surface function, that is, the time rate of change of the fractional-order complementary terminal sliding mode surface, is the fractional-order complementary terminal sliding mode surface function, 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 approach speed of the fractional-order complementary terminal sliding mode controller, g1, g2, and g3 are constants greater than 0, is a constant greater than 0 and less than 1, k is the phase of the three-phase power grid, k=(a,b,c), is a constant greater than 0, tanh() is the hyperbolic tangent function, and asinh() is the inverse hyperbolic sine function;

[0103] Specifically, the harmonic control function is:

[0104]

[0105] in, Indicates the DC side voltage, represents inductance, represents resistance, represents the control gain, Indicates harmonic current The derivative of is the harmonic current error of power, D represents the differential operator, ɑ represents the fractional order, g1, g2, g3 are constants greater than 0, (k=a,b,c) represents the three-phase power supply voltage, is a constant greater than 0 and less than 1, is a constant greater than 0.

[0106] In this embodiment, the Lyapunov function is selected as the stability function of the sliding mode control strategy design, namely:

[0107]

[0108] in, is the square of the fractional-order generalized sliding mode surface, is the square of the fractional-order compensation sliding surface, is the generalized energy function.

[0109] Then, the Lyapunov function is derived, and the derived 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 are substituted into the derivatives to obtain:

[0110]

[0111] in, represents the generalized energy function, Indicates the DC side voltage, Indicates harmonic current error The derivative of Indicates harmonic current The derivative of is a constant greater than 0 and less than 1;

[0112] Thus, the designed controller satisfies the Lyapunov stability condition and, therefore, the system is asymptotically stable.

[0113] S5. According to the harmonic control function, a control signal is calculated by a system dynamics algorithm to drive the inverter to output a harmonic compensation current.

[0114] Specifically, the implementation principle of step S5 in the above embodiment is as follows:

[0115] Based on three-phase power supply voltage (k=a,b,c), according to the circuit principle and Kirchhoff's theorem, the mathematical model of the active power filter is:

[0116]

[0117] in, represents the differential operator, 、 、 Represents the abc three-phase power supply voltage respectively, Indicates the DC side voltage, 、 、 They represent the abc three-phase currents (as compensation currents) output by the inverter and connected to the three-phase bus. 、 、 Respectively represent the control condition function of the three-phase power supply, represents inductance, Indicates resistance.

[0118] Assuming that the three-phase grid voltage is balanced, we can conclude that:

[0119]

[0120] Among them, O is the three-phase voltage reference grounding point, u aN 、u bN 、u cN Respectively represent the line voltages between points a, b, c and N on the AC side of the three-phase inverter; u NO Indicates the line voltage between point N and the reference ground point O. (k=a,b,c) is the switching function of the inverter IGBT (insulated gate bipolar transistor), which represents the on-off state of the main circuit switching device and is specifically defined as:

[0121]

[0122] when When is 1, the upper bridge arm is turned on and the lower bridge arm is turned off; When it is 0, the upper bridge arm is turned off and the lower bridge arm is turned on.

[0123] The dynamic model of the active power filter is obtained as follows:

[0124]

[0125] in, for The reciprocal, specifically, the control condition function S k (k=a,b,c) is expressed as:

[0126]

[0127] in, (k=a,b,c) is the switching function of the inverter IGBT (insulated gate bipolar transistor), and the control condition function S is obtained k The nonlinear matrix expression of is:

[0128]

[0129] in, 、 、 They represent the control condition functions of the abc three-phase power supply respectively, 、 、 They represent the switching functions of the inverter IGBT (insulated gate bipolar transistor) corresponding to the abc three-phase power supply.

[0130] To verify the use of the standard test function Sphere to simulate the butterfly optimization algorithm before and after improvement, the Sphere function expression is as follows:

[0131]

[0132] in, For the standard test function Sphere, For the test variable, is the square of the nth test variable.

[0133] like Figure 4 As shown in , the convergence speed of the improved butterfly optimization algorithm is significantly better than that of the butterfly optimization algorithm before improvement, and the minimum value obtained by the improved butterfly optimization algorithm is smaller than that obtained before improvement. Figure 5-Figure 8As shown, this embodiment outputs the waveform diagram and spectrum diagram 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. In order to further verify the superiority of the present invention, the control method proposed in the present invention (IBOA-FOCTSMC) is compared with terminal sliding mode control (TSMC), complementary sliding mode control (CSMC), complementary terminal sliding mode control (CTSMC) and fractional-order complementary terminal sliding mode control based on butterfly optimization (BOA-FOCTSMC). By building a corresponding simulation model and performing simulation, the absolute error of phase a current tracking and the filtering effect are obtained, as shown in Table 1.

[0134] Table 1 Schematic diagram of current tracking absolute error and filtering effect

[0135] Control strategy TSMC CSMC CTSMC BOA-FOCTSMC IBOA-FOCTSMC THD / % 1.75% 1.40% 1.11% 1.01% 0.67%

[0136] It can be seen from Table 1 above that the harmonic control effect (ie, THD) of the APF under the control strategy proposed in the present invention is better than that of the other four control strategies.

[0137] 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.

[0138] Example 2

[0139] like Figure 2 As shown, based on 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.

[0140] Specifically, the system includes a DC power supply module, a filter capacitor module, and an inverter module that are sequentially connected in signal mode. The three output terminals of the inverter module are connected to a three-phase power bus through an inductor L and a resistor r connected in series. The system also includes:

[0141] A DC side voltage fractional-order PI control module, configured to control the output voltage of the DC power supply module using a fractional-order PI control algorithm;

[0142] Harmonic separation module, used to perform harmonic separation on the grid current through instantaneous power algorithm to obtain three-phase harmonic current;

[0143] Filter capacitor module, used for preliminary filtering of three-phase harmonic current;

[0144] The current tracking control module is used to calculate the harmonic current tracking error based on the three-phase harmonic current and the inverter output current, and to calculate the harmonic control function based on the harmonic current tracking error using a fractional-order complementary terminal sliding mode control algorithm;

[0145] 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.

[0146] Specifically, the current tracking control module further includes:

[0147] A fractional-order generalized integral sliding mode surface unit is used to track the harmonic current tracking error by constructing a fractional-order generalized integral sliding mode surface;

[0148] 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;

[0149] A robust switching unit, configured to improve the robustness of the fractional-order complementary terminal sliding mode surface through a nonlinear reaching law;

[0150] 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, using the Lyapunov function as a stability function;

[0151] An improved butterfly algorithm optimizer is used to optimize the parameters of the fractional-order complementary terminal sliding surface through a reverse learning strategy, a Cauchy mutation strategy, and a random inertia weight strategy.

[0152] Specifically, the workflow of the system is:

[0153] First, the DC side voltage fractional-order PI control module uses a fractional-order PI control algorithm to output a reference voltage to ensure that the subsequent harmonic control process does not interfere with the harmonic separation caused by the controller current;

[0154] Then, the harmonic separation module uses the instantaneous power algorithm to separate the three-phase harmonic current from the three-phase grid current, and performs preliminary filtering through the filter capacitor module;

[0155] Then, the current tracking control module calculates the harmonic current tracking error based on the three-phase harmonic current and the inverter output current. Based on the harmonic current tracking error, the harmonic control function is calculated using the fractional-order complementary terminal sliding mode control algorithm.

[0156] Subsequently, the PWM drive module calculates the harmonic current control signal according to the harmonic control function through the system dynamics algorithm, and drives the inverter module to achieve tracking control of the three-phase current.

[0157] Example 3

[0158] like Figure 9 As shown, based on Example 1, this Example 3 proposes a terminal device of an active power filter current tracking control method based on an improved butterfly algorithm, and the terminal device 200 includes at least one memory 210, at least one processor 220, and a bus 230 connecting different platform systems.

[0159] The memory 210 may include a readable medium in the form of a volatile memory, such as a RAM 211 and / or a cache memory 212 , and may further include a ROM 213 .

[0160] The memory 210 also stores a computer program that can be executed by the processor 220, causing the processor 220 to perform any of the above-mentioned methods for current tracking control of active power filters based on the improved butterfly algorithm in the embodiments of the present application. The specific implementation method is consistent with the implementation method and the technical effects achieved in the embodiments of the above-mentioned methods, and some of the contents are not repeated here. The memory 210 may also include a program / utility 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 of these examples or some combination may include the implementation of a network environment.

[0161] Accordingly, the processor 220 may execute the aforementioned computer programs, as well as the program / utility 214 .

[0162] 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 a variety of bus architectures.

[0163] The terminal device 200 can also communicate with one or more external devices 240, such as keyboards, pointing devices, Bluetooth devices, etc., and can also communicate with one or more devices that can interact with the terminal device 200, and / or communicate with any device that enables the terminal device 200 to communicate with one or more other computing devices (such as routers, modems, etc.). Such communication can be carried out through the I / O interface 250. In addition, the terminal device 200 can also communicate with one or more networks (such as local area networks (LANs), wide area networks (WANs) and / or public networks, 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 conjunction 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.

[0164] Example 4

[0165] like Figure 10 As shown, based on Example 1, this embodiment proposes a computer-readable storage medium for an active power filter current tracking control method based on an improved butterfly algorithm. The computer-readable storage medium stores instructions that, when executed by a processor, implement any of the aforementioned active power filter current tracking control methods based on the improved butterfly algorithm. The specific implementation methods and technical effects achieved are consistent with those described in the aforementioned method embodiments, and some details are not repeated here.

[0166] Figure 10The program product 300 provided in this embodiment for implementing the above method is shown. It can use a portable compact disc read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product 300 of the present invention is not limited to this. In this embodiment, the readable storage medium can be any tangible medium that contains or stores a program, and the program can be used by or in conjunction with an instruction execution system, device, or device. The program product 300 can use any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any combination of the above. More specific examples of readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable disk, 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.

[0167] A computer-readable storage medium may include a data signal transmitted in baseband or as part of a carrier wave, carrying readable program code. This transmitted data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The readable storage medium may also be any readable medium other than a readable storage medium, which can transmit, transmit, or transfer 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 may be transmitted using any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination thereof. The program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a standalone software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. Where a remote computing device is involved, the remote computing device may 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 may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0168] The present invention is explained from the perspectives of purpose of use, effectiveness, progress and novelty. The practical progress it has is in compliance with 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 are not intended to limit this application. Therefore, all structures, devices, features, etc. that are similar or identical to those of this application, that is, all equivalent replacements or modifications made in accordance with the scope of this patent application, should fall within the scope of protection of this patent application.

[0169] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A current tracking control method for active power filter based on improved butterfly algorithm, characterized in that: The following steps are involved: S1. Perform harmonic separation on the three-phase grid current using an instantaneous power algorithm to obtain three-phase harmonic current; S2. Obtain the inverter output current, calculate the difference between the three-phase harmonic current and the inverter output current, 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, the butterfly algorithm is optimized using the reverse learning strategy, the Cauchy mutation strategy, and the random care weight strategy to obtain an improved butterfly optimizer; S4. Parameter optimization of the fractional-order complementary terminal sliding mode controller is performed by improving the butterfly optimizer, and a harmonic control function is calculated based on the sliding mode reaching law; S5. According to the harmonic control function, a control signal is calculated by a system dynamics algorithm to drive the inverter to output a harmonic compensation current.

2. The active power filter current tracking control method based on the improved butterfly algorithm according to claim 1 is characterized in that: Step S2 includes the following steps: S201. Based on the harmonic current tracking error, a fractional-order generalized integral sliding mode surface and a fractional-order complementary sliding mode surface are constructed respectively; S202. Superimposing the fractional-order generalized integral sliding surface and the fractional-order complementary sliding surface to obtain a fractional-order complementary terminal sliding surface; S203. Construct a fractional-order complementary terminal sliding mode controller based on 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, ε is a constant greater than 0, ɑ is the fractional order, S fgk (t) is the fractional order generalized integral sliding surface function, S fck (t) is the fractional-order complementary sliding surface function, D ɑ S fgk (t) is the fractional order expression of the fractional order generalized integral sliding mode surface, D ɑ S fck (t) is the fractional order expression of the fractional order complementary sliding mode surface, S fk (t) is the fractional-order complementary terminal sliding mode surface function.

3. The active power filter current tracking control method based on the improved butterfly algorithm according to claim 1 is characterized in that: The reverse learning strategy is: Among them, 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, and q is the elite reverse coefficient, which is a random number in (0, 1).

4. The active power filter current tracking control method based on the improved butterfly algorithm according to claim 1 is characterized in that: 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.

5. The active power filter current tracking control method based on the improved butterfly algorithm according to claim 1 is characterized in that: The random care weight strategy is: in, is the inertia weight at the z-th iteration, is the minimum value of the inertia weight constant, is the maximum value of the inertia weight constant, rand(0,1) is a random number between [0, 1], representing the random factor.

6. The active power filter current tracking control method based on the improved butterfly algorithm according to claim 1 is characterized in that: The sliding mode reaching law is: in, is the time derivative of the fractional-order complementary terminal sliding mode surface function, is the fractional-order complementary terminal sliding mode surface function, 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 a natural logarithmic function, g1, g2, and g3 are constants greater than 0, 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, the system being implemented based on the active power filter current tracking control method based on an improved butterfly algorithm as claimed in any one of claims 1 to 6, comprising a DC power supply module, a filter capacitor module and an inverter module connected in sequence, characterized in that: The system also includes: A DC side voltage fractional-order PI control module, configured to control the output voltage of the DC power supply module using a fractional-order PI control algorithm; Harmonic separation module, used to perform harmonic separation on the grid current through instantaneous power algorithm to obtain three-phase harmonic current; Filter capacitor module, used for preliminary filtering of three-phase harmonic current; The current tracking control module is used to calculate the harmonic current tracking error based on the three-phase harmonic current and the inverter output current, and to calculate the harmonic control function based on the harmonic current tracking error using 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.

8. The active power filter current tracking control system based on the 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 is used to track the harmonic current tracking error by constructing a fractional-order generalized integral sliding mode 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, configured 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 is used to calculate a harmonic control function based on the fractional-order complementary terminal sliding mode surface and the sliding mode reaching law, using the Lyapunov function as a stability function; An improved butterfly algorithm optimizer is used to optimize the parameters of the fractional-order complementary terminal sliding surface through a reverse learning strategy, a Cauchy mutation strategy, and a random inertia weight strategy.

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