High-frequency sub-harmonic compensation method and device for three-phase inverter system with multiple kinds of load access

Abstract

The invention provides a high-frequency harmonic compensation method and device for a three-phase inverter system with multiple loads accessed, and the method comprises the steps: obtaining a to-be-compensated harmonic current and the frequency information of the to-be-compensated harmonic current based on a harmonic load accessed by the three-phase inverter system; constructing a repetitive controller based on the harmonic current to be compensated; obtaining a modified repetitive controller based on the repetitive controller and the frequency information of the harmonic current to be compensated; obtaining a vector repetitive controller based on a preset vector twiddle factor, a preset translation length and the transformed repetitive controller; and based on the vector repetitive controller and the three-phase inverter system, generating a three-phase inverter system compensation current to compensate a harmonic current to be compensated. According to the invention, targeted accurate tracking and compensation are carried out on characteristic frequency harmonics generated by different harmonic loads, and the harmonic compensation effect is improved.

Description

Technical Field

[0001] The present invention relates to the field of harmonic suppression, and particularly to a high-frequency harmonic compensation method and device for a three-phase inverter system with multiple loads connected thereto. Background Art

[0002] As a link and tool for converting between the DC side and the AC side, in an environment where multiple loads are connected, the problem of harmonic interference generated by a three-phase inverter system becomes increasingly serious.

[0003] Currently, the prior art using the proportional-integral control method can only perform static-error-free tracking and control on the direct current obtained after Park transformation of the fundamental AC component in the three-phase inverter system, but the proportional-integral control method cannot track high-order harmonics; the prior art also uses the characteristic of the resonance peak at a specific frequency point of the proportional-resonant controller to achieve static-error-free tracking of a set frequency signal. However, if the proportional-resonant controller needs to track each harmonic of the three-phase inverter system, multiple proportional-resonant controllers need to be connected in parallel, which will cause instability problems in the three-phase inverter system. It can be seen that the prior art has poor harmonic compensation effects under the condition of frequent switching of multiple loads. Summary of the Invention

[0004] To solve the problem of poor harmonic compensation effect in the prior art, the present invention proposes a high-frequency harmonic compensation method and device for a three-phase inverter system with multiple loads connected thereto, which can achieve targeted and precise tracking and compensation of characteristic frequency harmonics generated by different harmonic loads, and improve the harmonic compensation effect.

[0005] To achieve the above object, an embodiment of the present invention provides a high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected thereto, which is applied to the three-phase inverter system and includes: based on the connection of harmonic loads to the three-phase inverter system, obtaining the harmonic current to be compensated and the frequency information of the harmonic current to be compensated; constructing a repetitive controller based on the harmonic current to be compensated; obtaining a modified repetitive controller based on the repetitive controller and the frequency information of the harmonic current to be compensated; obtaining a vector repetitive controller based on a preset vector rotation factor, a preset translation length, and the modified repetitive controller; and generating a compensation current for the three-phase inverter system based on the vector repetitive controller and the three-phase inverter system to compensate the harmonic current to be compensated.

[0006] The embodiment of the present invention proposes a high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses. By analyzing the harmonic loads accessed by the three-phase inverter system, the frequency information of the harmonic current to be compensated is obtained, providing the necessary signal phase and frequency information for subsequent processing. Then, a repetitive controller is constructed using the obtained harmonic current to be compensated, enabling the repetitive controller to track the zero steady-state error at all frequencies of the harmonic current to be compensated. Subsequently, the repetitive controller is modified using the frequency information of the harmonic current to be compensated to obtain a modified repetitive controller that can specifically track the frequencies that need to be compensated for the harmonic current to be compensated. Then, a vector rotation factor and a translation length are introduced to obtain a vector repetitive controller, which can translate the internal model structure of the repetitive controller, thereby realizing the tracking of multiple groups of harmonic frequencies to be compensated. Finally, the compensation current of the three-phase inverter system is generated according to the vector repetitive controller to compensate the harmonic current to be compensated. Thus, when multiple loads are connected to the three-phase inverter system, the above scheme is processed, which can not only accurately track the zero steady-state error at multiple frequencies but also achieve the zero steady-state error tracking of multiple groups of frequencies through the vector repetitive controller, ultimately realizing the targeted and accurate tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads and improving the harmonic compensation effect.

[0007] Further, based on the harmonic loads accessed by the three-phase inverter system, obtaining the harmonic current to be compensated and the frequency information of the harmonic current to be compensated includes: collecting three-phase voltages, converting the three-phase voltages into two-phase voltages based on a preset first coordinate transformation algorithm; obtaining the positive-sequence component of the two-phase voltages based on a preset integral phase-locked algorithm and the two-phase voltages; obtaining the phase-locked angle based on a preset angle rotation factor and the positive-sequence component of the two-phase voltages; and performing a matrix transformation on the harmonic loads accessed by the three-phase inverter system based on the phase-locked angle to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

[0008] Through the above scheme, the collected three-phase voltages are converted into two-phase voltages, and then the positive-sequence component of the two-phase voltages is obtained through the integral phase-locked algorithm to obtain the phase and frequency of the two-phase voltages. Then, a preset angle rotation factor is introduced to further obtain the phase-locked angle. After phase locking, a matrix transformation is performed on the harmonic loads accessed by the three-phase inverter system based on the phase-locked angle, which can convert the load operation into a linear operation, facilitating more accurate subsequent processing of the harmonic current to be compensated to obtain corresponding frequency and angle information, etc., and improving the harmonic compensation effect.

[0009] Furthermore, based on the phase-locking angle, a matrix transformation is performed on the harmonic load connected to the three-phase inverter system to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated, including: obtaining the first three-phase current based on the harmonic load connected to the three-phase inverter system; converting the first three-phase current into a first two-phase current based on a preset second coordinate transformation algorithm; obtaining the second two-phase current based on a preset transformation matrix, a phase-locking angle and the first two-phase current; obtaining the second three-phase current based on a preset low-pass filtering algorithm, a preset inverse transformation matrix and the second two-phase current; and obtaining the harmonic current to be compensated and the frequency information of the harmonic current to be compensated by subtracting the second three-phase current from the first three-phase current.

[0010] Through the above scheme, the load connected to the three-phase inverter system is analyzed, the three-phase current is extracted, and then further converted into a two-phase current. The complexity of the analysis and calculation is reduced by coordinate dimension reduction. Then, the two-phase current is further analyzed and converted into a three-phase current in combination with the phase-locked angle, low-pass filtering, transformation matrix and inverse transformation matrix. In this way, the fundamental wave and harmonic separation can be achieved, and the detection accuracy and tracking accuracy of the harmonics can be improved. After subtracting the previously extracted three-phase current, the frequency, amplitude and phase of the harmonic to be compensated are obtained, and then the current to be compensated and the frequency information of the harmonic current to be compensated are obtained. By analyzing the connected load, the current to be compensated and the corresponding frequency information are accurately obtained, providing a reliable data input basis for the subsequent generation of the compensation current. By analyzing the frequency information of the current to be compensated, an accuracy data basis is provided for the subsequent tracking of the harmonic frequency to be compensated, thereby achieving targeted and accurate tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads, and improving the effect of harmonic compensation.

[0011] Furthermore, based on the harmonic current to be compensated, a repetitive controller is constructed, including: based on a preset repetitive control coefficient, signal decomposition of the harmonic current to be compensated is performed to obtain a sinusoidal signal that is an integer multiple of each fundamental wave; based on a preset working frequency of the three-phase inverter system, a delay link of the repetitive controller is constructed; based on the sinusoidal signal that is an integer multiple of each fundamental wave and the delay link of the repetitive controller, a repetitive controller is constructed.

[0012] Through the above scheme, based on the preset repetitive control coefficient, the harmonic current to be compensated is decomposed in the frequency domain to separate the sinusoidal signals of integer multiples of the fundamental wave, so that the controller constructed subsequently can independently identify and process harmonics of different frequencies, and then according to the preset working frequency of the three-phase inverter system, the delay link of the repetitive controller is constructed to ensure the zero-static tracking of periodic harmonics. Finally, the decomposed harmonic signals are combined with the delay link to form a closed-loop control. At each cycle update, the controller dynamically adjusts the compensation amount according to the historical error to adapt to the changes in the harmonic amplitude and phase, thereby realizing targeted and accurate tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads, thereby improving the effect of harmonic compensation.

[0013] Further, based on the repetitive controller and the frequency information of the harmonic current to be compensated, a modified repetitive controller is obtained, including: based on the frequency information of the harmonic current to be compensated and the repetitive controller, reducing the delay link of the repetitive controller by a preset multiple to obtain the modified repetitive controller.

[0014] Through the above solution, by reducing the duration of the delay link of the repetitive controller and dynamically adjusting the control period in combination with the harmonic frequency information, the tracking speed and compensation accuracy for harmonics of different frequencies are further improved, and the effect of harmonic compensation is enhanced.

[0015] Further, based on a preset vector rotation factor, a preset translation length, and the modified repetitive controller, a vector repetitive controller is obtained, including: based on the modified repetitive controller, obtaining the resonant point of the modified repetitive controller; based on the preset translation length and the modified repetitive controller, translating the resonant point of the modified repetitive controller to obtain a translated repetitive controller; based on the translated repetitive controller and the preset vector rotation factor, constructing a vector repetitive controller.

[0016] Through the above solution, first, the resonant point of the modified repetitive controller is obtained, which can clarify the frequency of the harmonic current to be compensated. By introducing a vector rotation factor and a preset translation length to dynamically correct the phase of the compensation current, the phase lag caused by the delay of the traditional repetitive controller can be eliminated, and the phase and frequency matching characteristics of the control signal are further optimized on the basis of the modified repetitive controller, realizing the dynamic and precise alignment of harmonic compensation and improving the effect of harmonic compensation.

[0017] Further, based on the vector repetitive controller and the three-phase inverter system, a compensation current of the three-phase inverter system is generated to compensate the harmonic current to be compensated, including: embedding the vector repetitive controller into the three-phase inverter system to generate a signal modulation wave; based on the signal modulation wave, obtaining the switching trigger signals of the power tubes of the three-phase inverter system; based on the switching trigger signals of the power tubes of the three-phase inverter system, performing inversion through the DC-side capacitor of the three-phase inverter system to generate a compensation current of the three-phase inverter system; based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated, compensating the harmonic current to be compensated.

[0018] Through the above solution, based on the repetitive controller that has completed vector transformation, after embedding it into the three-phase inverter system, it can accurately track and compensate according to various loads connected to the three-phase inverter system. By generating a signal modulation wave to control the switching trigger signals of the power tubes of the three-phase inverter system, and then controlling the DC-side capacitor of the three-phase inverter system to perform inversion to generate the corresponding compensation current of the three-phase inverter system to compensate the harmonic current to be compensated, thereby realizing the closed-loop generation and dynamic compensation of harmonic current and improving the effect of harmonic compensation.

[0019] The embodiment of the present invention also provides a high-frequency harmonic compensation device for a three-phase inverter system with multiple load accesses, including: a harmonic processing module, a repetitive controller construction module, a repetitive controller modification module, a vector repetitive controller construction module, and a compensation current generation module; the harmonic processing module is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the harmonic load accessed by the three-phase inverter system; the repetitive controller construction module is used to construct a repetitive controller based on the harmonic current to be compensated; the repetitive controller modification module is used to obtain a modified repetitive controller based on the repetitive controller and the frequency information of the harmonic current to be compensated; the vector repetitive controller construction module is used to obtain a vector repetitive controller based on a preset vector rotation factor, a preset translation length, and the modified repetitive controller; the compensation current generation module is used to generate a compensation current for the three-phase inverter system based on the vector repetitive controller and the three-phase inverter system to compensate the harmonic current to be compensated.

[0020] The embodiment of the present invention proposes a high-frequency harmonic compensation device for a three-phase inverter system with multiple load accesses. The harmonic processing module analyzes the harmonic load accessed by the three-phase inverter system to obtain the frequency information of the harmonic current to be compensated, providing the necessary signal phase and frequency information for subsequent processing. Then, the repetitive controller construction module constructs a repetitive controller using the obtained harmonic current to be compensated, enabling the repetitive controller to track the zero steady-state error at all frequencies of the harmonic current to be compensated. Next, the repetitive controller modification module modifies the repetitive controller using the frequency information of the harmonic current to be compensated to obtain a modified repetitive controller, enabling the modified repetitive controller to specifically track the frequencies that need to be compensated for the harmonic current to be compensated. Then, the vector repetitive controller construction module introduces a vector rotation factor and a translation length to obtain a vector repetitive controller, which can translate the internal model structure of the repetitive controller, thereby realizing the tracking of multiple groups of harmonic frequencies to be compensated. Finally, the compensation current generation module generates the compensation current for the three-phase inverter system according to the vector repetitive controller to compensate the harmonic current to be compensated. Thus, when multiple loads are connected to the three-phase inverter system, the above scheme is processed. It can not only accurately track the zero steady-state error at multiple frequencies but also achieve the zero steady-state error tracking of multiple groups of frequencies through the vector repetitive controller, ultimately realizing the targeted and precise tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads and improving the effect of harmonic compensation.

[0021] Further, the harmonic processing module is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the three-phase inverter system accessing harmonic loads, including: a voltage acquisition unit, a positive-sequence component extraction unit, a phase-locked unit, and a matrix transformation unit; the voltage acquisition unit is used to collect three-phase voltages and convert the three-phase voltages into two-phase voltages based on a preset first coordinate transformation algorithm; the positive-sequence component extraction unit is used to obtain the positive-sequence components of the two-phase voltages based on a preset integral phase-locked algorithm and the two-phase voltages; the phase-locked unit is used to obtain a phase-locked angle based on a preset angle rotation factor and the positive-sequence components of the two-phase voltages; the matrix transformation unit is used to perform matrix transformation on the three-phase inverter system accessing harmonic loads based on the phase-locked angle to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

[0022] Through the above solution, the voltage acquisition unit converts the collected three-phase voltages into two-phase voltages, and the positive-sequence component extraction unit then obtains the positive-sequence components of the two-phase voltages through the integral phase-locked algorithm to obtain the phase and frequency of the two-phase voltages. Then, the phase-locked unit introduces a preset angle rotation factor to further obtain the phase-locked angle. After phase locking, the matrix transformation unit performs matrix transformation on the three-phase inverter system accessing harmonic loads based on the phase-locked angle, which can convert the load operation into a linear operation, facilitating more accurate subsequent processing of the harmonic current to be compensated to obtain corresponding frequency and angle information, etc., and improving the harmonic compensation effect.

[0023] Further, the compensation current generation module is used to generate the compensation current of the three-phase inverter system based on the vector repetitive controller and the three-phase inverter system to compensate the harmonic current to be compensated, including: a modulation wave generation unit, a signal acquisition unit, a compensation current generation unit, and a current compensation unit; the modulation wave generation unit is used to embed the vector repetitive controller into the three-phase inverter system to generate a signal modulation wave; the signal acquisition unit is used to obtain the switching trigger signals of the power tubes of the three-phase inverter system based on the signal modulation wave; the compensation current generation unit is used to perform inversion through the DC-side capacitor of the three-phase inverter system based on the switching trigger signals of the power tubes of the three-phase inverter system to generate the compensation current of the three-phase inverter system; the current compensation unit is used to compensate the harmonic current to be compensated based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated.

[0024] Through the above solution, based on the repetitive controller with vector transformation completed, after embedding it into the three-phase inverter system, it can perform precise tracking compensation according to various loads accessed by the three-phase inverter system. The modulation wave generation unit generates a signal modulation wave to control the signal acquisition unit to obtain the switching trigger signals of the power tubes of the three-phase inverter system, and then controls the compensation current generation unit to perform inversion through the DC-side capacitor of the three-phase inverter system to generate the corresponding compensation current of the three-phase inverter system. The current compensation unit compensates the harmonic current to be compensated, thereby realizing the closed-loop generation and dynamic compensation of harmonic current and improving the harmonic compensation effect. Description of the Drawings

[0025] Figure 1 Schematic diagram of the step flow of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0026] Figure 2 TOGI structure block diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0027] Figure 3 TOGI-PLL phase-locked loop structure block diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0028] Figure 4 Access load processing structure block diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0029] Figure 5 Repetitive controller structure diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0030] Figure 6 Modified repetitive controller structure diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0031] Figure 7 Vector repetitive controller structure diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0032] Figure 8 Overall structure block diagram of the three-phase inverter system of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0033] Figure 9 Schematic diagram of the grid-side current waveform of the uncompensated three-phase inverter system of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0034] Figure 10 Schematic diagram of the total harmonic distortion rate of the uncompensated three-phase inverter system of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0035] Figure 11 Schematic diagram of the grid-side current waveform of the compensated three-phase inverter system of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0036] Figure 12Schematic diagram of the total harmonic distortion rate of the three-phase inverter system after compensation by the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention;

[0037] Figure 13 Schematic diagram of the module structure of a high-frequency harmonic compensation device for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention. Specific implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] Embodiment 1

[0040] Refer to Figure 1 , Figure 1 which is a schematic flow chart of the steps of a high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention. As Figure 1 shown, the embodiment of the present invention proposes a high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses, including steps 101 to 105, and the specific steps are as follows:

[0041] Step 101, based on the harmonic load accessed by the three-phase inverter system, obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated;

[0042] Step 102, based on the harmonic current to be compensated, construct a repetitive controller;

[0043] Step 103, based on the repetitive controller and the frequency information of the harmonic current to be compensated, obtain a modified repetitive controller;

[0044] Step 104, based on a preset vector rotation factor, a preset translation length, and the modified repetitive controller, obtain a vector repetitive controller;

[0045] Step 105, based on the vector repetitive controller and the three-phase inverter system, generate a compensation current for the three-phase inverter system to compensate the harmonic current to be compensated.

[0046] Specific implementation manners. In this embodiment, the compensation process of the 6k±1 (pk±r, where p and r are parameters representing harmonic frequencies and k is a positive integer) harmonics generated by a three-phase inverter system is taken as an example for explanation. The three-phase inverter system is connected to a harmonic load for analysis and processing. The current to be compensated is extracted and the frequency information of the current to be compensated is analyzed. It can be obtained that the characteristic harmonics of the current to be compensated are concentrated at frequencies such as 5, 7, 11, and 13, which are 6k + 1 frequencies. Then, a repetitive controller is constructed based on the current to be compensated. A method such as fast Fourier decomposition can be used to determine the frequency information of the current to be compensated. The frequency information of the current to be compensated includes the amplitude and phase of each frequency. Among them, the amplitude is inversely proportional to the harmonic order. Harmonics at frequencies such as 5 and 11 are negative-sequence harmonics, and harmonics at frequencies such as 6 and 13 are positive-sequence harmonics. By modifying the internal model structure of the repetitive controller according to the frequency information of the current to be compensated, a modified repetitive controller can be obtained. Then, a vector rotation factor is introduced, and a vector repetitive controller is constructed on the basis of the modified repetitive controller. The general expression of the vector repetitive controller is generally:

[0047]

[0048] In the formula, G(z) is the transfer function of the output and error of the vector repetitive controller, K rc is the gain of the vector repetitive controller, with a value of 1, j is the introduced vector rotation factor, the translation length m is taken as 1, N is the delay length, and its value is the ratio of the system sampling frequency to the fundamental frequency. Here, the sampling frequency of the three-phase inverter system is 15 kHz, and the power frequency of the three-phase inverter system is 50 Hz. N = 15000 / 50 = 300. Q(z) is taken as the zero-phase low-pass filter (z + 0.5 + z -1 ) / 4, and the phase compensation S(z) is taken as z 4 ; Finally, the vector controller is embedded in the three-phase inverter system to generate the compensation current of the three-phase inverter system to compensate the harmonic current to be compensated. Taking the 6k±1 (k is a positive integer) harmonics generated by the three-phase inverter system as an example, finally, through the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses proposed in the embodiment of the present invention, the current waveform after compensation has been significantly improved, the harmonic distortion rate has been greatly reduced, the content rate of each harmonic has also decreased accordingly, and the total harmonic distortion rate THD is lower than the relevant domestic and foreign harmonic distortion rate standards of 5%. At the same time, the delay time and storage unit required for the modified appropriate repetitive controller to compensate the harmonic current to be compensated are only 1 / 6 of the traditional method.

[0049] The embodiment of the present invention proposes a high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses. By analyzing the harmonic loads accessed by the three-phase inverter system, the frequency information of the harmonic current to be compensated is obtained, providing the necessary signal phase and frequency information for subsequent processing. Then, a repetitive controller is constructed using the obtained harmonic current to be compensated, enabling the repetitive controller to track the zero steady-state error at all frequencies of the harmonic current to be compensated. Subsequently, the repetitive controller is modified using the frequency information of the harmonic current to be compensated to obtain a modified repetitive controller that can specifically track the frequencies that need to be compensated for the harmonic current to be compensated. Then, a vector rotation factor and a translation length are introduced to obtain a vector repetitive controller, which can translate the internal model structure of the repetitive controller, thereby realizing the tracking of multiple groups of harmonic frequencies to be compensated. Finally, the compensation current of the three-phase inverter system is generated according to the vector repetitive controller to compensate the harmonic current to be compensated. Thus, when multiple loads are connected to the three-phase inverter system, the above scheme is processed, which can not only accurately track the zero steady-state error at multiple frequencies but also realize the zero steady-state error tracking of multiple groups of frequencies through the vector repetitive controller, ultimately achieving targeted and precise tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads and improving the effect of harmonic compensation.

[0050] As an example of the embodiment of the present invention, step 101 is executed, including: collecting three-phase voltages, and converting the three-phase voltages into two-phase voltages based on a preset first coordinate transformation algorithm; obtaining the positive-sequence components of the two-phase voltages based on a preset integral phase-locked algorithm and the two-phase voltages; obtaining a phase-locked angle based on a preset angle rotation factor and the positive-sequence components of the two-phase voltages; and performing a matrix transformation on the harmonic loads accessed by the three-phase inverter system based on the phase-locked angle to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

[0051] Specifically, in this embodiment, a third-order generalized integrator phase-locked loop (TOGI-PLL) will be used to analyze the grid voltage. First, the grid information of the three-phase inverter system is sampled to obtain three-phase voltages v a 、v b and v c . Then, the three-phase voltages are subjected to Clarke coordinate transformation (equivalent to the preset first coordinate transformation algorithm) to transform the three-phase voltages from the three-phase abc stationary coordinate system to the αβ two-phase stationary coordinate system, obtaining two-phase voltages v α and v β . The specific transformation method is as follows:

[0052]

[0053] After coordinate transformation, the voltage in the αβ two-phase stationary coordinate system is passed through TOGI-PLL (equivalent to the preset integral phase-locked algorithm). By using its trigonometric function characteristics and filtering function, the positive sequence fundamental component of the two-phase voltage is accurately extracted to obtain its phase and frequency to realize the phase-locked link. See Figure 2 , Figure 2 A TOGI structural block diagram of a high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected provided in an embodiment of the present invention; Figure 2 As shown, in the TOGI link of integral phase locking, δ is the adjustment coefficient, which is 1.414; ω is the system angular frequency, which is 100πrad / s; the rectangular block diagram represents the integral link. According to the structural block diagram of TOGI, the transfer function expression of the output and input is as follows:

[0054]

[0055]

[0056] From the expression of the transfer function, we can get u 1 (t) and u 2 (t)-u 3 (t) is an orthogonal term, the amplitudes of the two are equal, and the phase of the latter lags the former by 90°. After the TOGI link, two orthogonal signals with the same amplitude and frequency as the input signal can be obtained. In the αβ two-phase stationary coordinate system, the input voltage signal v is generated by the generated orthogonal signal. α and v β After processing, a rotation factor with a 90-degree lag is introduced to obtain the positive sequence component of the two-phase voltage. The implementation method is as follows:

[0057]

[0058] Where q represents the rotation factor lagged by 90 degrees;

[0059] See also Figure 3 , Figure 3 A TOGI-PLL phase-locked loop structure block diagram of a high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected provided by an embodiment of the present invention; Figure 3 As shown in the figure, the positive sequence components of the two-phase voltages are obtained through the TOGI link, and the collected positive sequence components are transformed by αβ / dq. d After PI regulation and control, the system angular frequency ω is obtained, and the phase-locking angle θ is further integrated to complete the integral phase lock. The specific expression of αβ / dq conversion is as follows:

[0060]

[0061] Where θ is the phase-locked angle; in this embodiment, the third-order generalized integrator phase-locked loop TOGI-PLL is only taken as an example for explanation, and other existing technical means that can achieve the same effect can also be used as substitutes.

[0062] After obtaining the phase-locked angle θ through integral phase-locking, further analyze the three-phase inverter system connected to the harmonic load. Through matrix transformation, obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

[0063] Through the above scheme, the collected three-phase voltage is converted into two-phase voltage, and then the positive sequence components of the two-phase voltage are obtained through the integral phase-locking algorithm, so as to obtain the phase and frequency of the two-phase voltage. Then, a preset angle rotation factor is introduced to further obtain the phase-locked angle. After phase-locking, based on the phase-locked angle, matrix transformation is performed on the three-phase inverter system connected to the harmonic load, which can convert the load operation into a linear operation, facilitating more accurate subsequent processing of the harmonic current to be compensated to obtain corresponding frequency and angle information, etc., and improving the harmonic compensation effect.

[0064] Preferably, based on the phase-locked angle, matrix transformation is performed on the three-phase inverter system connected to the harmonic load to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated, including: obtaining the first three-phase current based on the three-phase inverter system connected to the harmonic load; converting the first three-phase current into the first two-phase current based on a preset second coordinate transformation algorithm; obtaining the second two-phase current based on a preset transformation matrix, the phase-locked angle, and the first two-phase current; obtaining the second three-phase current based on a preset low-pass filter algorithm, a preset inverse transformation matrix, and the second two-phase current; obtaining the harmonic current to be compensated and the frequency information of the harmonic current to be compensated by taking the difference between the second three-phase current and the first three-phase current.

[0065] Specifically implementable manner, after completing integral phase-locking, the frequency and angle information of the three-phase inverter system voltage can be obtained, and then the current to be compensated is further extracted and analyzed according to the phase-locked angle. For details, see Figure 4 , Figure 4 is the access load processing structure block diagram of the high-frequency harmonic compensation method for the three-phase inverter system with multiple loads connected provided in an embodiment of the present invention; as Figure 4 shown, detect the three-phase inverter system connected to the harmonic load, detect the three-phase currents i a 、i b and i c (equivalent to the first three-phase current), and then according to the C 32 transformation matrix (equivalent to the preset second coordinate transformation algorithm), convert the three-phase current into the first two-phase currents i α and i β , where the specific expression of the C 32 transformation matrix is as follows:

[0066]

[0067] Obtain two-phase currents \(i\) α and \(i\) β After that, through the transformation matrix \(C\) and the phase-locked angle \(\theta\), transform the first two-phase currents to obtain the second two-phase currents \(i\) p and \(i\) q , where the expression of the transformation matrix \(C\) is specifically as follows:

[0068]

[0069] Obtain the second two-phase currents \(i\) p and \(i\) q After that, through the low-pass filter LPF and the \(C\) 23 inverse transformation matrix, transform the second two-phase currents \(i\) p and \(i\) q into the second three-phase currents. Through the above processing, the current components \(i\) af , \(i\) bf and \(i\) cf of the three-phase currents can be obtained. Then, take the difference from the detected first three-phase currents to obtain the current components \(i\) ah , \(i\) bh and \(i\) ch of the harmonic current to be compensated, as well as the frequency information of the harmonic current to be compensated, such as the harmonic amplitude and phase of \(pk\pm r\), where \(p\) and \(r\) are parameters representing the harmonic frequencies, and \(k\) is a positive integer. For example, when \(p = 6\) and \(r = 1\), it represents the 6k±1 harmonic (such as the 5th, 7th, 11th, 13th harmonics, etc.). Among them, the \(C\) 23 specific expression of the inverse transformation matrix is as follows:

[0070]

[0071] Through the above solution, by analyzing the load connected to the three-phase inverter system, extract the three-phase currents, and then further transform them into two-phase currents. Reduce the complexity of analysis and calculation through coordinate dimension reduction. Then, combined with the phase-locked angle, low-pass filter, transformation matrix and inverse transformation matrix, further analyze the two-phase currents and then transform them into three-phase currents. In this way, the fundamental wave and harmonics can be separated, improving the detection accuracy and tracking accuracy of harmonics. After taking the difference from the previously extracted three-phase currents, obtain the harmonic frequencies, amplitudes and phases, etc. of the harmonic current to be compensated, and then obtain the current to be compensated and the frequency information of the harmonic current to be compensated. By analyzing the load connected, accurately obtain the current to be compensated and the corresponding frequency information, providing a reliable data input basis for the generation of the subsequent compensation current. Also, by analyzing the frequency information of the current to be compensated, provide an accurate data basis for the subsequent tracking of the harmonic frequencies to be compensated, and then realize the targeted and precise tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads, improving the effect of harmonic compensation.

[0072] As an example of an embodiment of the present invention, performing step 102 includes: decomposing the harmonic current to be compensated based on a preset repetition control coefficient to obtain sine signals that are integer multiples of the fundamental wave of each order; constructing a delay link of a repetitive controller based on the preset power frequency of the three-phase inverter system; and constructing a repetitive controller based on the sine signals that are integer multiples of the fundamental wave of each order and the delay link of the repetitive controller.

[0073] Specifically, in an implementable manner, by decomposing the harmonic current to be compensated into sine signals that are integer multiples of the fundamental wave of each order, and then combining with a sampling delay link, a repetitive signal generator for the sine signals that are integer multiples of the fundamental wave of each order is constructed. The transfer function of this generator contains poles at the frequencies of the above-mentioned harmonic currents to be compensated, and has infinite gain at the frequencies of the above-mentioned harmonic currents to be compensated, thereby realizing static error-free tracking of the given signal. Refer to Figure 5 , Figure 5 is the repetitive controller structure diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple loads access provided by an embodiment of the present invention; as Figure 5 shown, c(z) is the output signal of the repetitive controller, e(z) is the error signal of the repetitive controller, that is, the difference between the reference input signal and the output signal, K rc is the repetitive control coefficient (equivalent to the preset repetitive control coefficient), z -N is the delay link, where N = f s / f 0 , f s is the sampling frequency of the repetitive controller, taking 15 kHz; f 0 is the power frequency of the three-phase system, that is, 50 Hz. The specific expression of the transfer function of the constructed repetitive controller is as follows:

[0074]

[0075] It can be obtained from the transfer function of the repetitive controller that the repetitive controller contains poles at signal frequencies that are integer multiples of the power frequency of the three-phase system, and can realize static error-free tracking and compensation of the kth harmonic (k is a positive integer);

[0076] Through the above solution, based on a preset repetition control coefficient, the harmonic current to be compensated is decomposed in the frequency domain to separate sine signals that are integer multiples of each fundamental wave, enabling the subsequent constructed controller to independently identify and process harmonics of different frequencies. Then, based on the preset power frequency of the three-phase inverter system, a delay link of the repetitive controller is constructed to ensure zero-static-error tracking of periodic harmonics. Finally, the decomposed harmonic signals of each order are combined with the delay link to form a closed-loop control. At each cycle update, the controller dynamically adjusts the compensation amount according to the historical error to adapt to changes in the harmonic amplitude and phase, thereby achieving targeted and precise tracking and compensation of characteristic-frequency harmonics generated by different harmonic loads and improving the effect of harmonic compensation.

[0077] As an example of an embodiment of the present invention, performing step 103 includes: based on the harmonic current frequency information to be compensated and the repetitive controller, reducing the delay link of the repetitive controller by a preset multiple to obtain a modified repetitive controller.

[0078] For specific implementable ways, refer to Figure 6 , Figure 6 is the structure diagram of the modified repetitive controller for the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads access provided by a certain embodiment of the present invention; as Figure 6 shown, according to the harmonic current frequency information to be compensated, the internal model structure of the constructed repetitive controller is modified, and the delay link of one cycle of the original repetitive controller is reduced to 1 / n of the original, where n is the reduction multiple of the delay link, to obtain a modified repetitive controller, enabling it to perform targeted tracking and compensation on the detected harmonic current signal to be compensated, reducing the memory and time occupied by harmonic frequencies that do not need to be compensated. The transfer function expression of the modified repetitive controller is as follows:

[0079]

[0080] Through the above solution, by reducing the duration of the delay link of the repetitive controller and dynamically adjusting the control cycle in combination with the harmonic frequency information, the tracking speed and compensation accuracy for harmonics of different frequencies are further improved, and the effect of harmonic compensation is enhanced.

[0081] As an example of an embodiment of the present invention, performing step 104 includes: based on the modified repetitive controller, obtaining the resonant point of the modified repetitive controller; based on a preset translation length and the modified repetitive controller, translating the resonant point of the modified repetitive controller to obtain a translated repetitive controller; based on the translated repetitive controller and a preset vector rotation factor, constructing a vector repetitive controller.

[0082] For specific implementable ways, refer to Figure 7 , Figure 7Vector repetitive controller structure diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention; as Figure 7 shown, inside the repetitive controller is transformed by introducing a translation length m (equivalent to a preset translation length) and a vector rotation factor j (equivalent to a preset vector rotation factor). The translation length m can translate the resonant point of the internal model structure of the repetitive controller to achieve the compensation of the nk±m harmonics required by the repetitive controller. The vector rotation factor j can be represented by the ratio of two orthogonal signals in the two-phase stationary coordinate system, specifically expressed as e(z) α = e(z) β , where α and β are the two orthogonal axes of the two-phase stationary coordinate system. The general expression of the finally constructed vector repetitive controller is as follows:

[0083]

[0084] In the formula, G RC2 (z) is the transfer function of the vector repetitive controller, K rc is the repetitive control coefficient, whose value determines the magnitude of the error of the three-phase inverter system. j is the introduced vector rotation factor, m is the translation length, representing the frequency length to be translated, n is the delay link reduction multiple, representing the required reduction multiple of the delay link of the vector repetitive controller, and its value is a positive integer. N is the delay length, and its value is the ratio of the sampling frequency of the three-phase inverter system to the power frequency of the three-phase inverter system. Q(z) is a filter link introduced to enhance the system stability, and S(z) is a compensation link introduced to enhance the stability of the three-phase inverter system and improve the phase lag problem. By detecting the harmonics generated by the access of multiple loads, the harmonic frequencies to be compensated are obtained. By reasonably setting the reasonable values of parameters such as the harmonic frequency characteristics p and r, the harmonic compensation of pk±r (k is a positive integer) times can be achieved. In addition, by paralleling multiple different vector repetitive controller structures, the tracking and compensation of multiple groups of harmonic sequences can also be realized.

[0085] Through the above scheme, first, the resonant point of the transformed repetitive controller is obtained, and the frequency of the harmonic to be compensated can be determined. By introducing a vector rotation factor and a preset translation length to dynamically correct the phase of the compensation current, the phase lag caused by the delay of the traditional repetitive controller can be eliminated. On the basis of the transformed repetitive controller, the phase and frequency matching characteristics of the control signal are further optimized to achieve the dynamic and precise alignment of harmonic compensation and improve the effect of harmonic compensation.

[0086] As an example of an embodiment of the present invention, performing step 105 includes: embedding a vector repetitive controller into a three-phase inverter system to generate a signal modulation wave; obtaining a switching trigger signal for the power tubes of the three-phase inverter system based on the signal modulation wave; performing inversion through the DC-side capacitor of the three-phase inverter system based on the switching trigger signal for the power tubes of the three-phase inverter system to generate a compensation current for the three-phase inverter system; and compensating the harmonic current to be compensated based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated.

[0087] For specific implementable manners, refer to Figure 8 , Figure 8 which is the overall structural block diagram of the three-phase inverter system for high-frequency harmonic compensation of a three-phase inverter system with multiple load accesses provided in an embodiment of the present invention; as Figure 8 shown, embed the constructed vector repetitive controller into the three-phase inverter system, obtain the phase-locked angle θ through the TOGI-PLL phase-locked loop, input it to the harmonic detection and extraction to perform step 101, and extract the current i h to be compensated according to the nonlinear harmonic load connected to the three-phase inverter system, where i h includes components i ah , i bh and i ch , then construct and transform a repetitive controller according to steps 102-step 104, finally obtain a vector repetitive controller, input the current to be compensated into the vector repetitive controller to generate the modulation wave i ref required by the SPMW generator, and then the SPMW generator generates a trigger signal for controlling the switching of the power tubes of the three-phase inverter system according to the modulation wave i ref , specifically as shown in Figure 8 , the trigger signal controls the switching tubes S g1 , S g2 , S g3 , S g4 and D g1 , D g2 , where g = a, b, c. In this embodiment, there are three combined states for the switching tubes corresponding to the three phases a, b, and c. The positive state is that S g1 , S g2 are turned on and the other switching tubes are turned off; the zero state is that S g2 and D g1 are turned on or S g3 and D g2 are turned on and the other switching tubes are turned off; the negative state is that S g3 , S g4 are turned on and the other switching tubes are turned off. The trigger signal controls the turning on and off of the above switching tubes, and three combined states are used to generate sequences for each switch, and then the DC-side capacitor (equivalent to C 1 and C 2)By generating the required compensation current through inversion, by performing step 105, it is possible to achieve the compensation of the harmonic current generated by the compensating non-linear harmonic load, effectively reducing the current harmonic distortion rate of the three-phase inverter system and improving the power quality of the grid connection. See Figure 9 and Figure 10 , Figure 9 is a schematic diagram of the grid-side current waveform of the uncompensated three-phase inverter system for the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads access provided by an embodiment of the present invention; Figure 10 is a schematic diagram of the total harmonic distortion rate of the uncompensated three-phase inverter system for the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads access provided by an embodiment of the present invention. The total harmonic distortion rate is represented by THD (Total Harmonic Distortion) in the present invention, and its expression is as follows:

[0088]

[0089] Among them, I 1 represents the effective value of the fundamental wave current, I 2 2 , I 3 2 …In 2 are the squares of the effective values of the harmonic currents of each order;

[0090] As Figure 9 and Figure 10 shown, it can be seen from the waveform that the distortion of the current is large, and the total harmonic distortion rate THD exceeds 30%, and its harmonic frequencies are 6k + 1 frequencies such as 5, 7, 11, etc.; see Figure 11 and Figure 12 , Figure 11 is a schematic diagram of the grid-side current waveform of the compensated three-phase inverter system for the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads access provided by an embodiment of the present invention; Figure 12 is a schematic diagram of the total harmonic distortion rate of the compensated three-phase inverter system for the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads access provided by an embodiment of the present invention; As Figure 11 and Figure 12 shown, after compensation, the current waveform has been significantly improved, the harmonic distortion rate has been greatly reduced, and the content rate of each harmonic has also decreased accordingly. The total harmonic distortion rate THD has been reduced from the original 30.87% to 1.05%. The total harmonic distortion rate THD is lower than the relevant domestic and foreign harmonic distortion rate standards of 5%. In this embodiment, the vector repetitive control adopted requires fewer delay links and occupies less controller storage unit than the traditional control method, only 1 / n of the original. For example, to compensate for the 6k ± 1 harmonic, the required delay time and storage unit are only 1 / 6 of the traditional method.

[0091] Through the above solution, based on the repetitive controller completed with vector transformation, after embedding it into the three-phase inverter system, it can accurately track and compensate according to various loads connected to the three-phase inverter system. By generating a signal modulation wave to control the switching trigger signal of the power tubes in the three-phase inverter system, and then controlling the DC-side capacitor of the three-phase inverter system to perform inversion, a corresponding compensation current of the three-phase inverter system is generated to compensate the harmonic current to be compensated. Thus, the closed-loop generation and dynamic compensation of harmonic current are realized, and the effect of harmonic compensation is improved.

[0092] Embodiment 2

[0093] See Figure 13 , Figure 13 which is a schematic diagram of the module structure of a high-frequency harmonic compensation device for a three-phase inverter system with multiple loads connected, provided by an embodiment of the present invention. As Figure 13 shown, the high-frequency harmonic compensation device for a three-phase inverter system with multiple loads connected proposed in the embodiment of the present invention includes: a harmonic processing module 201, a repetitive controller construction module 202, a repetitive controller transformation module 203, a vector repetitive controller construction module 204, and a compensation current generation module 205; the harmonic processing module 201 is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the harmonic load connected to the three-phase inverter system; the repetitive controller construction module 202 is used to construct a repetitive controller based on the harmonic current to be compensated; the repetitive controller transformation module 203 is used to obtain a transformed repetitive controller based on the repetitive controller and the frequency information of the harmonic current to be compensated; the vector repetitive controller construction module 204 is used to obtain a vector repetitive controller based on a preset vector rotation factor, a preset translation length, and the transformed repetitive controller; the compensation current generation module 205 is used to generate a compensation current of the three-phase inverter system based on the vector repetitive controller and the three-phase inverter system to compensate the harmonic current to be compensated.

[0094] An embodiment of the present invention provides a high-frequency harmonic compensation device for a three-phase inverter system with multiple load accesses. The harmonic processing module analyzes the harmonic loads accessed by the three-phase inverter system to obtain the frequency information of the harmonic current to be compensated, providing the necessary signal phase and frequency information for subsequent processing. Then, the repetitive controller construction module uses the obtained harmonic current to be compensated to construct a repetitive controller, enabling the repetitive controller to track the steady-state error-free at all frequencies of the harmonic current to be compensated. Subsequently, the repetitive controller modification module uses the frequency information of the harmonic current to be compensated to modify the repetitive controller, obtaining a modified repetitive controller that can specifically track the frequencies that need to be compensated for the harmonic current to be compensated. Then, the vector repetitive controller construction module introduces a vector rotation factor and a translation length to obtain a vector repetitive controller that can translate the internal model structure of the repetitive controller, thereby achieving the tracking of multiple groups of harmonic frequencies to be compensated. Finally, the compensation current generation module generates the compensation current of the three-phase inverter system according to the vector repetitive controller to compensate for the harmonic current to be compensated. Thus, when multiple loads are connected to the three-phase inverter system, the above-mentioned scheme is processed. It can not only accurately track the steady-state error-free at multiple frequencies but also achieve the steady-state error-free tracking of multiple groups of frequencies through the vector repetitive controller, ultimately achieving targeted and precise tracking and compensation of the characteristic frequency harmonics generated by different harmonic loads and improving the harmonic compensation effect.

[0095] As an example of an embodiment of the present invention, the harmonic processing module 201 is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the harmonic loads accessed by the three-phase inverter system, including: a voltage acquisition unit 301, a positive sequence component extraction unit 302, a phase-locked unit 303, and a matrix transformation unit 304; the voltage acquisition unit 301 is used to collect the three-phase voltage and convert the three-phase voltage into two-phase voltage based on a preset first coordinate transformation algorithm; the positive sequence component extraction unit 302 is used to obtain the positive sequence component of the two-phase voltage based on a preset integral phase-locked algorithm and the two-phase voltage; the phase-locked unit 303 is used to obtain the phase-locked angle based on a preset angle rotation factor and the positive sequence component of the two-phase voltage; the matrix transformation unit 304 is used to perform matrix transformation on the harmonic loads accessed by the three-phase inverter system based on the phase-locked angle to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

[0096] In a specific implementable manner, in this embodiment, a third-order generalized integrator phase-locked loop (TOGI-PLL) will be used to analyze the grid voltage. First, the grid information of the three-phase inverter system is sampled to obtain the three-phase voltage, and then the three-phase voltage is subjected to Clarke coordinate transformation (equivalent to the preset first coordinate transformation algorithm) to transform the three-phase voltage from the three-phase abc stationary coordinate system to the αβ two-phase stationary coordinate system. The specific transformation method is as follows:

[0097]

[0098] After coordinate transformation, the voltage in the αβ two-phase stationary coordinate system passes through TOGI-PLL (equivalent to the preset integral phase-locked algorithm). By using its trigonometric function characteristics and filtering function, the positive-sequence fundamental components of the two-phase voltage can be accurately extracted, and their phase and frequency can be obtained to achieve the phase-locking link. See Figure 2 , Figure 2 is the TOGI structure block diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention; as Figure 2 shown, in the TOGI link of integral phase-locking, δ is the adjustment coefficient, taking 1.414; ω is the system angular frequency, taking 100π rad / s; the rectangular block diagram represents the integral link. According to the structure block diagram of TOGI, the transfer function expression of the output and input is as follows:

[0099]

[0100] From the expression of the transfer function, u 1 (t) and u 2 (t) - u 3 (t) are orthogonal terms. Their amplitudes are equal, and the phase of the latter lags behind the former by 90°. After passing through the TOGI link, two orthogonal signals with the same amplitude and frequency as the input signal can be obtained. In the αβ two-phase stationary coordinate system, the input voltage signals v α and v β are processed by introducing a rotation factor lagging by 90 degrees to obtain the positive-sequence components of the two-phase voltage. The implementation method is as described in the following formula:

[0101]

[0102] In the formula, q represents a rotation factor lagging by 90 degrees;

[0103] See Figure 3 , Figure 3 is the TOGI-PLL phase-locked loop structure block diagram of the high-frequency harmonic compensation method for a three-phase inverter system with multiple load accesses provided by an embodiment of the present invention; as Figure 3 shown, the positive-sequence components of the two-phase voltage are obtained through the TOGI link. The collected positive-sequence components are subjected to αβ / dq transformation. After the transformed v d is PI-regulated and controlled, the system angular frequency ω is obtained, and further integration gives the phase-locked angle θ to complete integral phase-locking. Among them, the specific expression of the αβ / dq transformation is as follows:

[0104]

[0105] In the formula, θ is the phase-locked angle; in this embodiment, the third-order generalized integrator phase-locked loop TOGI-PLL is only used as an example for explanation, and other existing technical means that can achieve the same effect can also be used as a substitute.

[0106] After completing the integral phase-locking to obtain the phase-locked angle θ, further analyze the three-phase inverter system connected to the harmonic load. Through matrix transformation, the harmonic current to be compensated and the frequency information of the harmonic current to be compensated are obtained.

[0107] Through the above scheme, the voltage acquisition unit converts the acquired three-phase voltage into two-phase voltage. The positive-sequence component extraction unit then obtains the positive-sequence components of the two-phase voltage through the integral phase-locking algorithm, thereby obtaining the phase and frequency of the two-phase voltage. Then, the phase-locking unit introduces a preset angle rotation factor to further obtain the phase-locked angle. After completing the phase-locking, the matrix transformation unit performs matrix transformation on the three-phase inverter system connected to the harmonic load based on the phase-locked angle, which can convert the load operation into a linear operation, facilitating more accurate subsequent processing of the harmonic current to be compensated to obtain corresponding frequency and angle information, etc., and improving the effect of harmonic compensation.

[0108] As an example of an embodiment of the present invention, the compensation current generation module is used to generate the compensation current of the three-phase inverter system based on the vector repetitive controller and the three-phase inverter system to compensate the harmonic current to be compensated, including: a modulation wave generation unit 401, a signal acquisition unit 402, a compensation current generation unit 403, and a current compensation unit 404; the modulation wave generation unit 401 is used to embed the vector repetitive controller into the three-phase inverter system to generate a signal modulation wave; the signal acquisition unit 402 is used to obtain the power tube switching trigger signal of the three-phase inverter system based on the signal modulation wave; the compensation current generation unit 403 is used to perform inversion through the DC-side capacitor of the three-phase inverter system based on the power tube switching trigger signal of the three-phase inverter system to generate the compensation current of the three-phase inverter system; the current compensation unit 404 is used to compensate the harmonic current to be compensated based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated.

[0109] For a specific implementable manner, refer to Figure 8 , Figure 8 which is the overall structure block diagram of the three-phase inverter system for high-frequency harmonic compensation of a multi-load access provided by an embodiment of the present invention; as Figure 8 shown, the constructed vector repetitive controller is embedded into the three-phase inverter system, and the phase-locked angle θ is obtained through the TOGI-PLL phase-locked loop and input to the harmonic detection and extraction execution step 101. According to the non-linear harmonic load connected to the three-phase inverter system, the current i h to be compensated is extracted, where i h includes components i ah 、ibh and i ch , and then construct a repetitive controller according to Steps 102 - 104 and transform it. Finally, a vector repetitive controller is obtained. Input the current to be compensated into the vector repetitive controller to generate the modulation wave i required by the SPMW generator ref , and then the SPMW generator generates the trigger signal for controlling the switching of the power tubes of the three - phase inverter system according to the modulation wave i ref , specifically as shown in Figure 8 . The trigger signals respectively control the switching tubes S g1 , S g2 , S g3 , S g4 and D g1 , D g2 , where g = a, b, c. In this embodiment, there are three combined states of the switching tubes corresponding to the three phases a, b, c. The positive state is that S g1 , S g2 are turned on and the rest of the switching tubes are turned off; the zero state is that S g2 and D g1 are turned on or S g3 and D g2 are turned on and the rest of the switching tubes are turned off; the negative state is that S g3 , S g4 are turned on and the rest of the switching tubes are turned off. The trigger signals respectively control the turning on and off of the above - mentioned switching tubes. From the three combined states, sequences of each switch are generated. Then, the DC - side capacitors (equivalent to C 1 and C 2 ) generate the required compensation current through inversion. By executing Step 105, it is possible to compensate for the harmonic current generated by compensating the non - linear harmonic load, effectively reducing the current harmonic distortion rate of the three - phase inverter system and improving the power quality of grid connection. Refer to Figure 9 and Figure 10 . Figure 9 is the schematic diagram of the grid - side current waveform of the uncompensated three - phase inverter system for the high - frequency harmonic compensation method of the three - phase inverter system with multiple loads connected provided by an embodiment of the present invention; Figure 10 is the schematic diagram of the total harmonic distortion rate of the uncompensated three - phase inverter system for the high - frequency harmonic compensation method of the three - phase inverter system with multiple loads connected provided by an embodiment of the present invention. The total harmonic distortion rate is represented by THD (Total Harmonic Distortion) in the present invention, and its expression is as follows:

[0110]

[0111] Among them, I 1 represents the effective value of the fundamental current, I 2 2 , I 32 …In 2 is the square of the effective value of each harmonic current;

[0112] As Figure 9 and Figure 10 shown, it can be seen from the waveform that the distortion of the current is relatively large, and the total harmonic distortion rate THD exceeds 30%. Its harmonic frequencies are 5, 7, 11, etc., which are 6k + 1 times frequencies; see Figure 11 and Figure 12 , Figure 11 is a schematic diagram of the grid-side current waveform of the three-phase inverter system after compensation by the high-frequency harmonic compensation method for a three-phase inverter system with multiple loads provided by an embodiment of the present invention; Figure 12 is a schematic diagram of the total harmonic distortion rate of the three-phase inverter system after compensation by the high-frequency harmonic compensation method for a three-phase inverter system with multiple loads provided by an embodiment of the present invention; As Figure 11 and Figure 12 shown, the current waveform after compensation has been significantly improved, the harmonic distortion rate has been greatly reduced, the content rate of each harmonic has also decreased accordingly, and the total harmonic distortion rate THD has been reduced from the original 30.87% to 1.05%. The total harmonic distortion rate THD is lower than the relevant domestic and foreign harmonic distortion rate standards of 5%. In this embodiment, the vector repetitive control adopted requires fewer delay links and occupies less controller storage units than the traditional control method, only 1 / n of the original. For example, to compensate for 6k ± 1 harmonic currents, the required delay time and storage units are only 1 / 6 of the traditional method.

[0113] Through the above solution, based on the repetitive controller that has completed the vector transformation, after embedding it into the three-phase inverter system, it can accurately track and compensate according to the multiple loads connected to the three-phase inverter system. The signal modulation wave control signal acquisition unit generates a signal modulation wave through the modulation wave generation unit to obtain the switching trigger signal of the power tube of the three-phase inverter system, and then controls the compensation current generation unit to invert the DC-side capacitor of the three-phase inverter system to generate the corresponding compensation current of the three-phase inverter system. The current compensation unit compensates the harmonic current to be compensated, thereby realizing the closed-loop generation and dynamic compensation of the harmonic current and improving the effect of harmonic compensation.

[0114] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

[0115] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0116] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

Claims

1. A high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected, characterized in that: Applied to a three-phase inverter system, the high-frequency harmonic compensation method of the three-phase inverter system with multiple loads connected includes: Based on the three-phase inverter system connected to the harmonic load, the harmonic current to be compensated and the frequency information of the harmonic current to be compensated are obtained; Based on the harmonic current to be compensated, construct a repetitive controller; Based on the repetitive controller and the frequency information of the harmonic current to be compensated, a modified repetitive controller is obtained; Based on a preset vector rotation factor, a preset translation length and the modified repetitive controller, a vector repetitive controller is obtained; Based on the vector repetitive controller and the three-phase inverter system, a three-phase inverter system compensation current is generated to compensate for a harmonic current to be compensated.

2. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 1, characterized in that: The method of accessing the harmonic load based on the three-phase inverter system to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated includes: Collecting three-phase voltage, and converting the three-phase voltage into two-phase voltage based on a preset first coordinate transformation algorithm; Based on a preset integral phase-locked algorithm and the two-phase voltage, a positive sequence component of the two-phase voltage is obtained; Obtaining a phase-locking angle based on a preset angle rotation factor and a positive sequence component of the two-phase voltage; Based on the phase-locked angle, matrix transformation is performed on the harmonic load connected to the three-phase inverter system to obtain information on the harmonic current to be compensated and the frequency of the harmonic current to be compensated.

3. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 2, characterized in that: Based on the phase-locked angle, matrix transformation is performed on the harmonic load connected to the three-phase inverter system to obtain information on the harmonic current to be compensated and the frequency of the harmonic current to be compensated, including: Based on the three-phase inverter system accessing the harmonic load, the first three-phase current is obtained; Based on a preset second coordinate transformation algorithm, converting the first three-phase current into a first two-phase current; Obtaining a second two-phase current based on a preset transformation matrix, the phase-locked angle and the first two-phase current; Based on a preset low-pass filtering algorithm, a preset inverse transformation matrix and the second two-phase current, a second three-phase current is obtained; By making a difference between the second three-phase current and the first three-phase current, the harmonic current to be compensated and the frequency information of the harmonic current to be compensated are obtained.

4. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 1, characterized in that: The method of constructing a repetitive controller based on the harmonic current to be compensated comprises: Based on a preset repetitive control coefficient, the harmonic current to be compensated is decomposed to obtain a sinusoidal signal of an integer multiple of each fundamental wave; Based on the preset power frequency of the three-phase inverter system, a repetitive controller delay link is constructed; A repetitive controller is constructed based on the sinusoidal signals of integer multiples of each fundamental wave and the delay link of the repetitive controller.

5. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 4, characterized in that: Based on the repetitive controller and the frequency information of the harmonic current to be compensated, a modified repetitive controller is obtained, including: Based on the frequency information of the harmonic current to be compensated and the repetitive controller, the delay link of the repetitive controller is reduced by a preset multiple to obtain a modified repetitive controller.

6. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 5, characterized in that: The method of obtaining a vector repetitive controller based on a preset vector rotation factor, a preset translation length and the modified repetitive controller comprises: Based on the modified repetitive controller, obtaining a resonant point of the modified repetitive controller; Based on a preset translation length and the modified repetitive controller, the resonance point of the modified repetitive controller is translated to obtain a translation repetitive controller; A vector repetitive controller is constructed based on the translation repetitive controller and the preset vector rotation factor.

7. The high-frequency harmonic compensation method for a three-phase inverter system with multiple loads connected as claimed in claim 1, characterized in that: Based on the vector repetitive controller and the three-phase inverter system, generating a three-phase inverter system compensation current to compensate for the harmonic current to be compensated includes: The vector repetitive controller is embedded in the three-phase inverter system to generate a signal modulation wave; Based on the signal modulation wave, a power tube switch trigger signal of the three-phase inverter system is obtained; Based on the trigger signal of the power tube switch of the three-phase inverter system, the three-phase inverter system DC side capacitor is used for inversion to generate a three-phase inverter system compensation current; Based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated, the harmonic current to be compensated is compensated.

8. A high-frequency harmonic compensation device for a three-phase inverter system with multiple loads connected, characterized in that: The method for compensating high-frequency harmonics of a three-phase inverter system with multiple loads connected as claimed in any one of claims 1 to 7 comprises: A harmonic processing module, a repetitive controller building module, a repetitive controller transformation module, a vector repetitive controller building module and a compensation current generation module; The harmonic processing module is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the access of the three-phase inverter system to the harmonic load; The repetitive controller building module is used to build a repetitive controller based on the harmonic current to be compensated; The repetitive controller transformation module is used to obtain a transformed repetitive controller based on the repetitive controller and the frequency information of the harmonic current to be compensated; The vector repetitive controller construction module is used to obtain a vector repetitive controller based on a preset vector rotation factor, a preset translation length and the transformed repetitive controller; The compensation current generating module is used for generating a three-phase inverter system compensation current based on the vector repetitive controller and the three-phase inverter system to compensate for the harmonic current to be compensated.

9. The high-frequency harmonic compensation device for a three-phase inverter system with multiple loads connected as claimed in claim 8, characterized in that: The harmonic processing module is used to obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated based on the three-phase inverter system accessing the harmonic load, including: Voltage acquisition unit, positive sequence component extraction unit, phase locking unit and matrix conversion unit; The voltage acquisition unit is used to acquire the three-phase voltage and convert the three-phase voltage into a two-phase voltage based on a preset first coordinate transformation algorithm; The positive sequence component extraction unit is used to obtain the positive sequence component of the two-phase voltage based on a preset integral phase-locked algorithm and the two-phase voltage; The phase locking unit is used to obtain a phase locking angle based on a preset angle rotation factor and a positive sequence component of the two-phase voltage; The matrix conversion unit is used to perform matrix conversion on the harmonic load connected to the three-phase inverter system based on the phase-locked angle, and obtain the harmonic current to be compensated and the frequency information of the harmonic current to be compensated.

10. The high-frequency harmonic compensation device for a three-phase inverter system with multiple loads connected as claimed in claim 8, characterized in that: The compensation current generating module is used to generate a three-phase inverter system compensation current to compensate for the harmonic current to be compensated based on the vector repetitive controller and the three-phase inverter system, including: A modulation wave generating unit, a signal acquiring unit, a compensation current generating unit and a current compensating unit; The modulation wave generating unit is used to embed the vector repetitive controller into the three-phase inverter system to generate a signal modulation wave; The signal acquisition unit is used to acquire a three-phase inverter system power tube switch trigger signal based on the signal modulation wave; The compensation current generating unit is used for generating a compensation current of the three-phase inverter system by inverting through the DC side capacitor of the three-phase inverter system based on the trigger signal of the power tube switch of the three-phase inverter system; The current compensation unit is used to compensate the harmonic current to be compensated based on the compensation current of the three-phase inverter system and the frequency information of the harmonic current to be compensated.

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