Harmonic suppression method, device and equipment of Hell moving average filter and medium

Abstract

The invention provides a harmonic suppression method, device and equipment for a Hull moving average filter and a medium. The harmonic suppression method comprises the steps of collecting load end current; based on an improved harmonic current detection method, a harmonic current instruction signal is detected and extracted according to a load end current; controlling the harmonic current command signal to pass through an active power filter to generate a compensation current; and the compensation current is injected into the power grid. The technical problems that in a traditional harmonic and reactive current detection method, unavoidable losses are brought to the dynamic response speed and accuracy of current detection, and the harmonic compensation performance of a system is finally affected are solved.

Description

Technical Field

[0001] This invention relates to the field of power quality technology, and more specifically, to a harmonic suppression method based on a Hull moving average filter, a harmonic suppression device based on a Hull moving average filter, an electronic device, and a readable storage medium. Background Technology

[0002] With the advancement of modern mining industrialization, mine-use frequency converter power supply systems are increasingly facing power quality problems, especially harmonic pollution and reactive power issues. The prevalence of harmonic sources in mine-use frequency converter power supply systems leads to frequent voltage and current waveform distortions, affecting the normal operation of equipment and potentially causing overheating, damage, or errors in the production process. In severe cases, it can even cause the collapse or failure of the mine-use frequency converter power supply system. Furthermore, the presence of reactive power causes system voltage fluctuations, affecting the stability and reliability of the mine-use frequency converter power supply system.

[0003] To address these issues, active power filters are often used to suppress harmonic currents and provide reactive power compensation in mine variable frequency power supply systems. Active power filters effectively improve power quality, reduce power loss, and increase equipment operating efficiency by accurately detecting and dynamically compensating for harmonic and reactive currents in the system.

[0004] However, at least one of the following problems exists in the relevant technologies: existing active power filters still face some challenges in practical applications, especially in terms of harmonic and reactive current detection and control strategies. Traditional methods for detecting harmonics and reactive current require the use of low-pass filters to extract the DC component. However, practical low-pass filters inevitably have a certain delay and cannot achieve truly pure DC filtering. This inevitably leads to losses in the dynamic response speed and accuracy of current detection, ultimately affecting the system's harmonic compensation performance. Summary of the Invention

[0005] This invention addresses the technical problem that traditional methods for detecting harmonics and reactive current inevitably lead to losses in the dynamic response speed and accuracy of current detection, ultimately affecting the harmonic compensation performance of the system.

[0006] To address the aforementioned problems, this invention provides a harmonic suppression method based on a Hull moving average filter, comprising: acquiring load-side current; detecting and extracting a harmonic current command signal based on the load-side current using an improved harmonic current detection method; controlling the harmonic current command signal to pass through an active power filter to generate a compensation current; and injecting the compensation current into the power grid.

[0007] Compared with existing technologies, the technical effects achieved by this technical solution are as follows: The improved harmonic current detection method in this application is an improved method based on instantaneous reactive power. The harmonic current detection method uses a Hull moving average phase-locked loop to detect and extract a sinusoidal signal that is in phase and frequency with the grid voltage, replacing the detection of the grid voltage. When the grid voltage is unbalanced or distorted, the phase and frequency information of the voltage fundamental frequency component is detected to replace the unbalanced voltage vector, greatly expanding the application range of the improved harmonic current detection method.

[0008] In one embodiment of the present invention, the improved harmonic current detection method employs a Hull moving average filter and a Hull moving average phase-locked loop. Based on the improved harmonic current detection method, the method detects and extracts a harmonic current command signal according to the load terminal current, including: acquiring a first three-phase current signal and a first three-phase voltage signal according to the load terminal current; performing coordinate transformation on the first three-phase current signal to obtain a second current signal; outputting a DC component after the second current signal passes through a Hull moving average filter; and calculating and outputting a harmonic current command signal based on the first three-phase current signal and the DC component.

[0009] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: This application uses a Hull moving average filter, which has a faster dynamic response speed and higher filtering accuracy in load current detection than traditional low-pass filters, greatly reducing the amount of computation and making it easier to apply digitally.

[0010] In one embodiment of the present invention, the first three-phase current signal is transformed to obtain a second current signal, including: converting the first three-phase current signal into a first current signal in a two-phase stationary coordinate system; and converting the first current signal into a second current signal in a two-phase rotating coordinate system.

[0011] Compared with existing technologies, the technical effects achieved by this solution are: it simplifies the analysis and calculation process of current signals; in a two-phase rotating coordinate system, the phase frequency characteristics of current and voltage are more direct, which facilitates subsequent harmonic extraction.

[0012] In one embodiment of the present invention, based on the improved harmonic current detection method, the method detects and extracts harmonic current command signals according to the load terminal current, and further includes: converting a first three-phase voltage signal into a first voltage signal in a two-phase rotating coordinate system; inputting the first voltage signal to a loop filter to output a control signal; converting the control signal into a frequency signal, and feeding the frequency signal back to a phase detector to obtain the phase. Based on the Hull moving average phase-locked loop, the output voltage sine and cosine values ​​are determined according to the first three-phase voltage signal.

[0013] Compared with existing technologies, the technical effect achieved by adopting this technical solution is that the output voltage sine and cosine values ​​are used as reference inputs for filtering.

[0014] In one embodiment of the invention, the loop filter consists of a cascaded Hull moving average filter and a PI controller.

[0015] Compared with existing technologies, the technical effects achieved by this solution are as follows: The HMA-PLL used in this application improves the structure of traditional phase-locked loops, exhibiting excellent anti-interference performance and fast and accurate phase-locking capability. This novel phase-locked loop structure can improve the phase angle detection accuracy of the phase-locked loop and is suitable for power grid environments with high harmonic interference. Simultaneously, the HMA moving average of this application possesses sensitivity comparable to fractal adaptive moving averages (with very low hysteresis), and also improves smoothness locally, effectively minimizing hysteresis while ensuring smoothness.

[0016] In one embodiment of the present invention, the active power filter includes: a command current calculation circuit, a harmonic current control circuit, a drive circuit, and a main circuit. The main circuit includes: a PWM converter and an inverter. Controlling the harmonic current command signal to pass through the active power filter to generate a compensation current includes: injecting the harmonic current command signal into the harmonic current control circuit for control; the harmonic current control circuit controls the PWM converter to modulate and generate waves, and outputs a three-phase modulated wave; controlling the switching action of the inverter according to the three-phase modulated wave, and outputting a compensation current.

[0017] Compared with existing technologies, the technical effects achieved by this technical solution are as follows: the harmonic current command signal is injected into the harmonic current control circuit; the current inner loop controls PWM modulation and wave generation, and the three-phase modulated wave is output through the PWM converter control; then the main circuit inverter switches to operate, outputs compensation current, and injects it into the grid to compensate for the harmonic components caused by nonlinear loads. The compensation current injected into the grid makes the grid contain only the fundamental frequency component.

[0018] In one embodiment of the present invention, before acquiring the load current, the harmonic suppression method further includes: preprocessing the initial signal generated at the load end using a passive high-pass filter to obtain the load current.

[0019] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: First, the initial signal is preprocessed by a passive high-pass filter, which provides a basis for compensation for the subsequent active power filter, reduces the burden on APF control, and reduces low-frequency noise interference.

[0020] On the other hand, embodiments of the present invention also provide a harmonic suppression device based on a Hull moving average filter, using a harmonic suppression method based on a Hull moving average filter as described in any of the above embodiments, comprising: an acquisition module for acquiring load-side current; a detection module for detecting and extracting a harmonic current command signal based on the load-side current using an improved harmonic current detection method; a processing module for controlling the harmonic current command signal to pass through an active power filter to generate a compensation current; and a control module for injecting the compensation current into the power grid.

[0021] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: The harmonic suppression device based on the Hull moving average filter in this embodiment is used to implement the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, and therefore it has all the beneficial effects of the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, which will not be repeated here.

[0022] In another aspect, embodiments of the present invention also provide an electronic device, the electronic device including: a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein when the program or instructions are executed by the processor, the steps of the harmonic suppression method based on the Hull moving average filter as described in any of the above embodiments are implemented.

[0023] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: The electronic device in this embodiment operates the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, and therefore has all the beneficial effects of the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, which will not be repeated here.

[0024] In another aspect, embodiments of the present invention also provide a readable storage medium storing a program or instructions that, when executed by a processor, implement the steps of the harmonic suppression method based on a Hull moving average filter as described in any of the above embodiments.

[0025] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: The readable storage medium in this embodiment is used to store the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, and therefore it has all the beneficial effects of the harmonic suppression method based on the Hull moving average filter as in any embodiment of the present invention, which will not be repeated here.

[0026] By adopting the technical solution of the present invention, the following technical effects can be achieved: (1) The improved harmonic current detection method in this application is an improved method based on instantaneous reactive power. The harmonic current detection method uses a Hull moving average phase-locked loop to detect and extract a sinusoidal signal that is in the same frequency and phase as the grid voltage, replacing the detection of the grid voltage. When the grid voltage is unbalanced or distorted, the phase and frequency information of the voltage fundamental frequency component is detected to replace the unbalanced voltage vector, which greatly expands the application range of the improved harmonic current detection method. (2) This application uses a Hull moving average filter, which has a faster dynamic response speed and higher filtering accuracy than traditional low-pass filters in load current detection, greatly reducing the amount of computation and making it easy to apply digitally. (3) The HMA-PLL used in this application improves the structure of the traditional phase-locked loop, and has good anti-interference performance and fast and accurate phase-locking capability. This new phase-locked loop structure can improve the phase angle detection accuracy of the phase-locked loop and is suitable for power grid environments with high harmonic interference; (4) The HMA moving average of this application has the same sensitivity as the fractal adaptive moving average (very low lag) and also improves the smoothness locally, thus achieving the maximum reduction of lag while ensuring smoothness. (5) First, the initial signal is preprocessed by a passive high-pass filter to provide a basis for compensation for the subsequent active power filter, reduce the burden of APF control and reduce low-frequency noise interference. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 A flowchart of a harmonic suppression method based on a Hull moving average filter provided in Embodiment 1 of the present invention; Figure 2 A detailed flowchart of a harmonic suppression method based on a Hull moving average filter provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the active power filter of the present invention; Figure 4 This is a schematic diagram illustrating the detection principle of the improved harmonic current detection method in this invention. Figure 5 This is a schematic diagram of the Hull moving average phase-locked loop in this invention; Figure 6 This is a schematic block diagram of a harmonic suppression device based on a Hull moving average filter provided in Embodiment 2 of the present invention; Figure 7 This is a block diagram of an electronic device provided in Embodiment 3 of the present invention; Figure 8 This is a schematic diagram of the structure of a readable storage medium provided in Embodiment 4 of the present invention.

[0028] Explanation of reference numerals in the attached figures: 11-AC power supply; 12-Harmonic source; 20-Active power filter; 21-Command current calculation circuit; 22-Harmonic current control circuit; 23-Drive circuit; 241-PWM converter; 242-Inverter; 100-Harmonic suppression device; 101-Acquisition module; 102-Detection module; 103-Processing module; 104-Control module; 200-Electronic device; 210-Memory; 211-Computer program; 220-Processor; 300-Readable storage medium; 310-Computer-executable instructions. Detailed Implementation

[0029] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1 See Figure 1 This is a flowchart of a harmonic suppression method based on a Hull moving average filter provided in the first embodiment of the present invention, combined with... Figure 2 Harmonic suppression methods based on Hull moving average filters include: S100: Collects load current; S200: Based on an improved harmonic current detection method, it detects and extracts harmonic current command signals according to the load terminal current; S300: The control harmonic current command signal passes through the active power filter to generate compensation current; S400: Injects compensation current into the power grid.

[0031] In one specific embodiment, see Figure 3 This is a schematic diagram of the APF system, on the left. The AC power source 11 is located on the far right, and the nonlinear load 12 is a harmonic source. The nonlinear load generates harmonics and consumes reactive power. For grid current, This is the converter output current, used to compensate for harmonic currents. For harmonic current command, The detected load-side current. The active power filter detects harmonic currents from the nonlinear load end, and a compensation device generates a compensation current of equal magnitude but opposite polarity to the harmonic current, which is injected into the power grid to cancel the harmonics generated at the nonlinear load end, ensuring that the grid current contains only the fundamental component. The active power filter 20 (APF) mainly consists of a command current calculation circuit 21, a harmonic current control circuit 22, a drive circuit 23, and a main circuit.

[0032] The command current calculation circuit adopts an improved harmonic current detection method. The load end current is extracted by the command current calculation circuit to obtain the harmonic current command signal. The command current calculation stage is the harmonic current detection stage, which is used to extract the harmonic current command signal. The compensation current is controlled by the harmonic current control circuit in the active power filter, and then the main circuit outputs the compensation current. The compensation current injected into the power grid makes the power grid contain only the fundamental frequency component.

[0033] The improved harmonic current detection method in this application is based on an improved method of instantaneous reactive power. The harmonic current detection method uses a Hull moving average phase-locked loop to detect and extract a sinusoidal signal that is in phase and frequency with the grid voltage, replacing the detection of the grid voltage. When the grid voltage is unbalanced or distorted, the phase and frequency information of the voltage fundamental frequency component is detected to replace the unbalanced voltage vector, greatly expanding the application range of the improved harmonic current detection method.

[0034] Preferably, the load current is collected at the nonlinear load end through a circuit transformer.

[0035] Furthermore, the improved harmonic current detection method employs a Hull moving average filter and a Hull moving average phase-locked loop, S200 including: S210: Obtain the first three-phase current signal and the first three-phase voltage signal based on the load terminal current; S220: Perform coordinate transformation on the first three-phase current signal to obtain the second current signal; S230: The second current signal is output as a DC component after passing through the Hull moving average filter; S240: Calculates and outputs harmonic current command signals based on the first three-phase current signals and DC components.

[0036] Furthermore, S220 includes: S221: Convert the first three-phase current signal into the first current signal in the two-phase stationary coordinate system; S222: Convert the first current signal into a second current signal in a two-phase rotating coordinate system.

[0037] Specifically, this application uses a Hull moving average filter, which has a faster dynamic response speed and higher filtering accuracy than traditional low-pass filters in load current detection, greatly reducing the amount of computation and making it easier for digital applications; it also simplifies the analysis and calculation process of current signals. In a two-phase rotating coordinate system, the phase frequency characteristics of current and voltage are more direct, which facilitates subsequent harmonic extraction.

[0038] See Figure 4 First, the input first three-phase current signal is transformed into a coordinate system. Specifically, the first three-phase current signal is first converted into a current signal in a two-phase stationary coordinate system (defined here as the first current signal). ; In the formula, , , These are the currents for phases A, B, and C, respectively. The first three-phase current signals include: , and ; , Let α and β be the currents in the two-phase stationary coordinate systems α and β, respectively. The first current signal includes: and ; This is the transformation matrix of the Clark transform, which is used to convert a three-phase stationary coordinate system into a two-phase stationary perpendicular coordinate system. .

[0039] The first current signal is transformed using coordinates to obtain the second current signal: ; In the formula, , These are the currents in the two-phase rotating coordinate system, and the second current signal includes: and C is the transformation matrix from a two-phase stationary coordinate system to a two-phase rotating coordinate system. , Let t be the angular frequency and t be the time.

[0040] Combining the above formulas: ; After the first three-phase current signal undergoes transformations in a two-phase stationary coordinate system and a two-phase rotating coordinate system, it is converted into a second current signal. The fundamental component is converted into a DC component (also known as the fundamental DC component), and the harmonic components are converted into AC components (also known as harmonic AC components). In other words... , It includes both the DC component converted from the fundamental frequency component and the AC component converted from the harmonic components.

[0041] Subsequently, the second current signal flows through a Hull moving average filter (HMA) to output the two-phase instantaneous active DC components. , The two-phase instantaneous active DC components of the HMA output are inversely transformed: ; In the formula, , This represents the DC component in a two-phase rotating coordinate system. It is the inverse transformation matrix of the C transformation matrix; , The DC component in a two-phase stationary coordinate system. , .

[0042] according to , Output DC component: ; In the formula, , , These are the DC components of phases A, B, and C, respectively. for The inverse transformation matrix of the transformation matrix.

[0043] Subtract the DC component from the input first and third phase current signals to output the AC component: ; In the formula, , , These are the AC components for phases A, B, and C, respectively.

[0044] Output AC components , , Afterwards, , , As a harmonic current command signal The harmonic current is injected into the harmonic current control circuit of the active power filter.

[0045] Preferably, the design of the Hull Moving Average (HMA) filter is an improvement on the simple moving average algorithm. The simple moving average operates within a window T, where the filtering function takes the value of 1 / T at each time point, using the formula: In the formula, The filter value at time t. For filtering functions, The input values ​​are the time series values. t represents time, and i represents the time points within the time window T.

[0046] The low-frequency trend at time t is calculated and used. The filter function within the window of the Weighted Moving Average (WMA) decreases linearly from the current data to the data from the previous T-1 periods. Therefore, the value of the filter function in period ti... for The weight is a monotonically decreasing linear function of i. After determining the weight, the weighted moving average at time t is obtained by the following formula: ; Weighted moving averages are more sensitive to recent changes, but they still exhibit lag. Therefore, the following Hull moving weighted average algorithm is introduced, with the following steps: ①. Calculate the weighted moving average with the nearest window of T / 2, denoted as WMA1 (round down if T / 2 is not an integer).

[0047] ②. Calculate the weighted moving average with a window of T, denoted as WMA2.

[0048] ③. Subtract the result of the second step from the result of the first step, and then add the result of the third step to obtain a new time series.

[0049] ④. Using the time series obtained in step 3 as the object, calculate the weighted moving average of the window (rounded down if not an integer). The mathematical expression for the above step is: ; In the formula, int represents integer rounding.

[0050] ⑤. Discretization to facilitate implementation on digital filters: The z-domain expression after discretization of the weighted moving average: In the formula, H(z) is the transfer function of the weighted moving average.

[0051] For a weighted moving average of window int(T / 2): ; Nested WMA calculations will The new WMA is computed as input: .

[0052] ⑥. Subtract : In the formula, The transfer function for the Hull moving average.

[0053] The final expression is: ; In the formula, T is the most important parameter in HMA design, and its setting must balance the dynamic response speed and filtering performance of the HMA. Typically, the selection principle for T is based on filtering out the lowest second-major harmonic frequency contained in the power grid.

[0054] Furthermore, the S200 also includes: The first three-phase voltage signal is converted into the first voltage signal in a two-phase rotating coordinate system; The first voltage signal is input to the loop filter to output a control signal; The control signal is converted into a frequency signal, which is then fed back to the phase detector to obtain the phase. ; Based on the Hull moving average phase-locked loop, the output voltage sine and cosine values ​​are determined according to the first three-phase voltage signals.

[0055] Specifically, this step uses the output voltage sine and cosine values ​​as reference inputs for filtering.

[0056] Furthermore, the loop filter consists of a cascaded Hull moving average filter and a PI controller.

[0057] Specifically, HMA-PLL, or Hull Moving Average Phase-Locked Loop, can also be called an improved phase-locked loop based on the Hull moving average filter. For example... Figure 5 As shown, v abc It is a three-phase voltage. The voltage along the d-axis. This is the q-axis voltage. This is the proportionality coefficient. The integral coefficient is... As the output angle, the abc / dq module is used to simulate the phase detector in a phase-locked loop, to determine the phase of the input voltage signal and output an error signal; The module represents a loop filter, which performs high-frequency processing on the error signal and filters out high-frequency components. The module represents a voltage-controlled oscillator, which is used to convert control signals into frequency signals and send the results back to the phase detector to form a closed-loop control until phase locking is completed.

[0058] The three-phase voltage signal at the nonlinear load terminal is input to the HMA-PLL, which outputs sine and cosine values. The specific steps include: 1. Performing Clark and Park transformations on the first three-phase voltage signal input to the HMA-PLL to convert it into a first voltage signal in a two-phase rotating coordinate system; 2. Controlling the projection of the three-phase voltage composite vector onto the q-axis. , and When the input is fed into the loop filter, At this time, the three-phase voltage composite vector 1. Coinciding with the d-axis, a steady state is formed; 2. The loop filter consists of a cascaded HMA and PI controller module. The HMA performs a low-pass filter on the first voltage signal, filtering out high-frequency signals (frequency jumps, amplitude jumps, phase jumps, harmonics, noise, DC interference, etc.), removing high-frequency components from the error signal, and outputting a control signal; 3. The control signal is sent to the voltage-controlled oscillator (VCO). An integral module is used to represent the VCO converting the control signal into a frequency signal and feeding the result back to the phase detector. The adjustment method is negative feedback adjustment. The VCO uses an integral module to represent the phase, and finally obtains the phase. 5. The sine and cosine values ​​of the output voltage of the Hull moving average phase-locked loop are processed in the next step.

[0059] The HMA-PLL used in this application improves upon the structure of traditional phase-locked loops, exhibiting excellent anti-interference performance and fast, accurate phase-locking capability. This novel phase-locked loop structure enhances the phase angle detection accuracy of the phase-locked loop and is suitable for power grid environments with high harmonic interference.

[0060] Meanwhile, the HMA moving average of this application has sensitivity comparable to fractal adaptive moving average (with very low lag), and also improves smoothness locally, truly achieving the maximum reduction of lag while ensuring smoothness.

[0061] Furthermore, the active power filter 20 includes: a command current calculation circuit 21, a harmonic current control circuit 22, a drive circuit 23, and a main circuit, the main circuit including: a PWM converter 241 and an inverter 242; S300 includes: S310: Injects the harmonic current command signal into the harmonic current control circuit for control. S320: Harmonic current control circuit controls the modulation and waveform generation of the PWM converter, and outputs a three-phase modulated waveform; S330: Controls the switching action of the inverter according to the three-phase modulation wave and outputs compensation current.

[0062] Specifically, the harmonic current command signal obtained in S200 is injected into the harmonic current control circuit; the inner current loop controls PWM modulation and waveform generation, and the three-phase modulated wave is output through the PWM converter 241; then, the main circuit inverter 242 is controlled to switch, outputting a compensation current, which is injected into the power grid to compensate for the harmonic components caused by the nonlinear load. The compensation current injected into the power grid ensures that only the fundamental frequency component exists in the grid. In this application, the harmonic current command signal is input into the inner current loop for control, making the actual current value approach the reference value.

[0063] Preferably, the PWM converter 241 serves as the main circuit, generating a compensation current. The compensation current injected into the power grid is equal in magnitude and opposite in direction to the harmonic components in the load current, thus canceling each other out.

[0064] The harmonic current command signal is input into the harmonic current control circuit. The current tracking circuit is the first link in the compensation current control circuit. Its function is to obtain the signal for controlling the on / off of each device in the main circuit of the compensation current generating circuit based on the relationship between the compensation current command signal and the actual compensation current. The result should ensure that the compensation current tracks the changes of its command signal.

[0065] Furthermore, prior to S100, the harmonic suppression method also includes: preprocessing the initial signal generated at the load end using a passive high-pass filter to obtain the load end current.

[0066] Specifically, before S100, the initial signal is preprocessed using a passive high-pass filter to provide a compensation basis for the subsequent active power filter, reducing the burden on APF control and minimizing low-frequency noise interference. This application employs a second-order high-pass filter (HPF), which has lower fundamental loss and better impedance-frequency characteristics compared to a first-order HPF. On one hand, it can eliminate harmonics caused by the switching of components in the main circuit during compensation; on the other hand, it can filter out higher-order harmonics in the compensation target, thus reducing the requirements for the switching frequency of components in the main circuit of the active power filter, making it relatively easier to achieve large capacity. Furthermore, the passive high-pass filter has a simple structure, is easy to maintain, has low cost, and is widely used in engineering.

[0067]

Example 2

[0068] In one specific embodiment, the acquisition module 101, detection module 102, processing module 103, and control module 104 of the harmonic suppression device 100 based on the Hull moving average filter cooperate to implement the harmonic suppression method based on the Hull moving average filter as described in the first embodiment above, which will not be repeated here.

[0069]

Example 3

[0070]

Example 4

[0071] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0072] If the functionality is implemented as a software module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A harmonic suppression method based on a Hull moving average filter, characterized in that, The harmonic suppression method includes: Collect the load current; Based on the improved harmonic current detection method, the harmonic current command signal is detected and extracted according to the load terminal current; The control signal for the harmonic current passes through an active power filter to generate a compensation current; The compensation current is injected into the power grid.

2. The harmonic suppression method according to claim 1, characterized in that, The improved harmonic current detection method employs the Hull moving average filter and the Hull moving average phase-locked loop. The improved harmonic current detection method detects and extracts harmonic current command signals based on the load terminal current, including: The first three-phase current signal and the first three-phase voltage signal are obtained based on the load terminal current. The first three-phase current signal is transformed into coordinates to obtain the second current signal; The second current signal, after passing through the Hull moving average filter, outputs a DC component; The harmonic current command signal is calculated and output based on the first three-phase current signal and the DC component.

3. The harmonic suppression method according to claim 2, characterized in that, The step of performing coordinate transformation on the first three-phase current signal to obtain the second current signal includes: The first three-phase current signal is converted into a first current signal in a two-phase stationary coordinate system; The first current signal is converted into the second current signal in a two-phase rotating coordinate system.

4. The harmonic suppression method according to claim 2, characterized in that, The improved harmonic current detection method, which detects and extracts harmonic current command signals based on the load terminal current, further includes: The first three-phase voltage signal is converted into a first voltage signal in a two-phase rotating coordinate system; The first voltage signal is input to the loop filter to output a control signal; The control signal is converted into a frequency signal, and the frequency signal is fed back to the phase detector to obtain the phase. ; Based on the Hull moving average phase-locked loop, the voltage sine and voltage cosine values ​​are output according to the first three-phase voltage signal.

5. The harmonic suppression method according to claim 4, characterized in that, The loop filter is composed of a cascaded Hull moving average filter and a PI controller.

6. The harmonic suppression method according to claim 1, characterized in that, The active power filter includes: a command current calculation circuit, a harmonic current control circuit, a drive circuit, and a main circuit. The main circuit includes: a PWM converter and an inverter. The control signal for the harmonic current passes through an active power filter to generate a compensation current, including: The harmonic current command signal is injected into the harmonic current control circuit for control. The harmonic current control circuit controls the modulation and wave generation of the PWM converter and outputs a three-phase modulated wave. The inverter's switching action is controlled according to the three-phase modulation wave, and the compensation current is output.

7. The harmonic suppression method according to claim 1, characterized in that, Before acquiring the load terminal current, the harmonic suppression method further includes: The initial signal generated at the load end is preprocessed by a passive high-pass filter to obtain the load end current.

8. A harmonic suppression device based on a Hull moving average filter, wherein the harmonic suppression device uses the harmonic suppression method based on a Hull moving average filter as described in any one of claims 1-7, characterized in that, The harmonic suppression device includes: The acquisition module is used to acquire the load current. The detection module is used to detect and extract harmonic current command signals based on the load terminal current using an improved harmonic current detection method. The processing module is used to control the harmonic current command signal to pass through an active power filter to generate a compensation current; A control module is provided for injecting the compensation current into the power grid.

9. An electronic device, characterized in that, The electronic device includes: a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the steps of the harmonic suppression method based on the Hull moving average filter as described in any one of claims 1 to 7.

10. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed by a processor, implement the steps of the harmonic suppression method based on a Hull moving average filter as described in any one of claims 1 to 7.

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