Power grid harmonic detection and control method of adaptive generalized integrator

Abstract

The invention relates to a power grid harmonic detection and control method for a self-adaptive generalized integrator, and the method comprises the steps: improving the stable filtering capability and frequency selection capability of the generalized integrator under a frequency fluctuation condition through introducing an orthogonal feed-forward amplitude compensation branch; the filtering performance of the original generalized integrator on fifth and seventh harmonics is optimized, and the harmonic detection precision is improved; by adjusting the coefficient of the single-stage controller, no-static-error tracking can be carried out on any harmonic signal, and the universality of control under different harmonic working conditions is improved.

Description

Technical Field

[0001] The present application relates to the field of inverter control, and in particular to a grid harmonic detection and control method using an adaptive generalized integrator. Background Art

[0002] The generalized integrator has frequency selection and bandpass characteristics, and can track and eliminate fundamental frequency and multiple frequency harmonic signals. It is often used in grid-connected inverters to detect and control harmonics. At present, with the high proportion of distributed renewable energy and high-power nonlinear power electronic loads connected to the power grid system, the harmonic currents in the system become complicated, and the fluctuation of source and load causes the grid frequency to change within a certain range. At the same time, there are also the influences of DC bias and unbalanced components. Under this condition, the classic generalized integrator cannot stably detect and control the harmonics in the system due to structural limitations, which will lead to an increase in grid-connected harmonic components and steady-state errors. Therefore, in order to ensure high-quality grid-connected signals, it is particularly important to design a harmonic detection and control method for a frequency-adaptive generalized integrator, considering the harmonic detection and tracking requirements under various conditions such as frequency fluctuations.

[0003] Due to the limitation of fixed parameters, the detection and control of the classic generalized integrator under frequency fluctuation conditions will produce amplitude errors, and the detection ability of the 5th and 7th low-order harmonics is weak. In terms of harmonic detection, many researchers have proposed corresponding harmonic detection methods based on the characteristics of different generalized integrators, including reduced-order generalized integrators, second-order generalized integrators, third-order generalized integrators, and cascaded generalized integrators. These methods have improved the performance of generalized integrators under different conditions, but the bandpass characteristics make it impossible to solve the problem of poor detection accuracy of the 5th and 7th harmonics by generalized integrators. At the same time, the limitation of fixed parameters makes it impossible to eliminate the amplitude error under frequency fluctuation conditions. The introduction of frequency feedback branches can adjust the performance of generalized integrators according to the real-time grid frequency, and the introduction of low-pass filters in the feedback branches can further optimize it, but it is found that adding feedback branches will cause stability and other problems. In terms of harmonic control, second-order generalized integrators are often used to track harmonics without static errors, but the harmonic selection characteristics of generalized integrators are not fully utilized; some researchers use the frequency selection and phase sequence decoupling characteristics of reduced-order integrators to track harmonics, but the parameter design process of this method is complex and the amount of calculation is large; some researchers have also optimized the control method of generalized integration, and proposed an improved second-order generalized integrator with a first-order differential link and a reduced-order generalized proportional-integral controller. Although these methods improve the original control performance of the generalized integrator, they do not have the ability to adaptively adjust the frequency and cannot meet the harmonic control requirements under frequency fluctuation conditions. Summary of the invention

[0004] In order to overcome at least one deficiency in the prior art, the present application provides a grid harmonic detection and control method using an adaptive generalized integrator.

[0005] In a first aspect, a method for detecting harmonics in a power grid using an adaptive generalized integrator is provided, comprising:

[0006] Perform Clark transformation on the three-phase power grid signal to obtain a two-phase orthogonal signal;

[0007] The high-order harmonics and DC components in the two-phase orthogonal signal are filtered out to obtain a filtered orthogonal signal;

[0008] Performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal;

[0009] Performing positive and negative sequence separation on the signal after the first compensation to obtain a positive sequence component;

[0010] Perform Park transformation on the positive sequence component, convert the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtain the signal after Park transformation;

[0011] Tracking the sixth harmonic in the signal after Park transformation and performing orthogonal feedforward amplitude compensation to obtain a second compensated signal;

[0012] The Park transformed signal is subtracted from the second compensated signal to eliminate the sixth harmonic, thereby obtaining a final filtered signal;

[0013] Performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal;

[0014] The two-phase orthogonal signal is subtracted from the signal after inverse Park transformation to obtain a harmonic signal.

[0015] In one embodiment, quadrature feedforward amplitude compensation is performed on the filtered quadrature signal to obtain a first compensated signal using the following formula:

[0016]

[0017] Among them, e αo1 、e qαo1 、e βo1 、e qβo1 are the four signal components in the filtered orthogonal signal, e qαo1 With e αo1 Orthogonal, e qβo1 With e βo1 Orthogonal; are the four signal components in the first compensated signal; ω is the fundamental angular frequency, k is the damping coefficient; ω r is the real-time angular frequency of the power grid.

[0018] In one embodiment, performing positive and negative sequence separation on the first compensated signal to obtain a positive sequence component includes:

[0019]

[0020] in, are four signal components in the first compensated signal; and are the two signal components of the positive sequence component.

[0021] In one embodiment, the sixth harmonic in the Park transformed signal is tracked and orthogonal feedforward amplitude compensated to obtain a second compensated signal, including:

[0022] Track the sixth harmonic in the signal after Park transformation to obtain the tracked signal. The transfer function used is:

[0023]

[0024] Among them, D SOGI , Q SOGI are two transfer functions used for the two signal components of the Park transformed signal in the tracking process, s is a variable in the frequency domain, ω' is the sixth angular frequency of the fundamental wave, and k is the damping coefficient;

[0025] The orthogonal feedforward amplitude compensation is performed on the tracked signal using the following formula:

[0026]

[0027] Among them, e αo 、e βo are the two signal components of the signal after tracking; are the two signal components of the second compensated signal, ω is the fundamental angular frequency, ω r is the real-time angular frequency of the power grid.

[0028] In a second aspect, a method for controlling power grid harmonics using an adaptive generalized integrator is provided, comprising:

[0029] Feedback control is performed on the first harmonic signal to obtain a first feedback-controlled signal; feedback control is performed on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained according to the above-mentioned power grid harmonic detection method of the adaptive generalized integrator;

[0030] Performing multi-control-level tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, wherein each control level obtains the signal after the first tracking compensation and the signal after the second tracking compensation;

[0031] Performing proportional control on the signal after the first feedback control to obtain a first proportionally controlled signal; performing proportional control on the signal after the second feedback control to obtain a second proportionally controlled signal;

[0032] The signal after the first proportional control is accumulated with the signal after the first tracking compensation corresponding to each control stage to obtain a first control signal; the first control signal is used to perform feedback control on the first harmonic signal;

[0033] The signal after the second proportional control is accumulated with the signal after the second tracking compensation corresponding to each control stage to obtain a second control signal; the second control signal is used to perform feedback control on the second harmonic signal.

[0034] In one embodiment, the closed-loop transfer function used for tracking is:

[0035]

[0036] Among them, H SOGI is the closed-loop transfer function, k s is the proportional control coefficient, ω c is the cutoff angular frequency, s is the variable in the frequency domain, and ω is the fundamental angular frequency.

[0037] In one embodiment, the signal after the first tracking compensation and the signal after the second tracking compensation are expressed by the following formula:

[0038]

[0039] in, is the signal after the first tracking compensation, is the signal after the second tracking compensation, u αo is the signal after the first feedback control, u βo is the signal after the second feedback control, ω is the fundamental angular frequency, ω g is the angular frequency of the power grid, ω c is the cut-off angular frequency, and k is the damping coefficient.

[0040] In a third aspect, a power grid harmonic detection device of an adaptive generalized integrator is provided, comprising:

[0041] Clark transformation module, used to perform Clark transformation on three-phase power grid signals to obtain two-phase orthogonal signals;

[0042] A third-order generalized integrator is used to filter out the high-order harmonics and DC components in the two-phase orthogonal signal to obtain a filtered orthogonal signal;

[0043] An orthogonal feedforward amplitude compensation module, used for performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal;

[0044] A positive-negative sequence separation module, used for performing positive-negative sequence separation on the first compensated signal to obtain a positive-sequence component;

[0045] Park transformation module, used to perform Park transformation on the positive sequence component, convert the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtain the signal after Park transformation;

[0046] A tracking and compensation module is used to track the sixth harmonic in the signal after Park transformation and perform orthogonal feedforward amplitude compensation to obtain a second compensated signal;

[0047] A first subtraction module is used to subtract the Park transformed signal from the second compensated signal to eliminate the sixth harmonic and obtain a final filtered signal;

[0048] An inverse Park transform module, used for performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal;

[0049] The second subtraction module is used to subtract the two-phase orthogonal signal from the signal after inverse Park transformation to obtain a harmonic signal.

[0050] In a fourth aspect, a power grid harmonic control device of an adaptive generalized integrator is provided, comprising:

[0051] A feedback control module, used for performing feedback control on the first harmonic signal to obtain a first feedback-controlled signal; performing feedback control on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained according to the above-mentioned power grid harmonic detection method of the adaptive generalized integrator;

[0052] A multi-level tracking and compensation module, used for performing multi-control-level tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, wherein each control level corresponds to obtaining the signal after the first tracking compensation and the signal after the second tracking compensation;

[0053] A proportional control module, used to perform proportional control on the signal after the first feedback control to obtain a first proportionally controlled signal; and perform proportional control on the signal after the second feedback control to obtain a second proportionally controlled signal;

[0054] An accumulation module is used to accumulate the signal after the first proportional control and the signal after the first tracking compensation corresponding to each control level to obtain a first control signal; the first control signal is used to perform feedback control on the first harmonic signal; the signal after the second proportional control and the signal after the second tracking compensation corresponding to each control level are accumulated to obtain a second control signal; the second control signal is used to perform feedback control on the second harmonic signal.

[0055] Compared with the prior art, the present application has the following beneficial effects: the grid harmonic detection and control method of the adaptive generalized integrator of the present application improves the stable filtering capability and frequency selection capability of the generalized integrator under frequency fluctuation conditions by introducing an orthogonal feedforward amplitude compensation branch; optimizes the filtering performance of the original generalized integrator for the 5th and 7th harmonics, and improves the harmonic detection accuracy; by adjusting the coefficient of the single-stage controller, any harmonic signal can be tracked without static error, thereby improving the versatility of control under different harmonic conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present application may be better understood by referring to the following description given in conjunction with the accompanying drawings, which together with the following detailed description are included in this specification and form a part of this specification. In the drawings:

[0057] Figure 1 A schematic diagram of a power grid harmonic detection method based on an adaptive generalized integrator is shown;

[0058] Figure 2 shows the principle diagram of orthogonal feedforward amplitude compensation;

[0059] Figure 3 The schematic diagram of positive and negative sequence separation is shown;

[0060] Figure 4 The schematic diagram of the power grid harmonic control method using an adaptive generalized integrator is shown;

[0061] Figure 5 A schematic diagram of an active power filter detection and control system model is shown;

[0062] Figure 6 The waveform diagrams of the power grid signal, the filter output signal and the detected output harmonic signal under different working conditions are shown;

[0063] Figure 7The harmonic current and spectrum diagram of the harmonic control structure output using an adaptive generalized integrator under two harmonic conditions of different frequencies are shown, where (a) is the harmonic current and spectrum diagram without tracking control under a 49Hz high distortion rate condition, (b) is the current and spectrum diagram after tracking control and harmonic treatment under a 49Hz high distortion rate condition, (c) is the harmonic current and spectrum diagram without tracking control under a 51Hz low distortion rate condition, and (d) is the current and spectrum diagram after tracking control and harmonic treatment under a 51Hz low distortion rate condition. DETAILED DESCRIPTION

[0064] The exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that many implementation-specific decisions can be made in the process of developing any such actual embodiments in order to achieve the specific goals of the developer, and these decisions may vary from embodiment to embodiment.

[0065] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure closely related to the scheme according to the present application is shown in the drawings, while other details that are not closely related to the present application are omitted.

[0066] It should be understood that the present application is not limited to the described implementation forms due to the following description with reference to the accompanying drawings. In this article, where feasible, the embodiments can be combined with each other, features between different embodiments can be replaced or borrowed, and one or more features can be omitted in one embodiment.

[0067] The present application provides a method for detecting harmonics in a power grid using an adaptive generalized integrator. Figure 1 The schematic diagram of the power grid harmonic detection method based on the adaptive generalized integrator is shown in FIG. Figure 1 , methods include:

[0068] Step S11, Clark transformation is performed on the three-phase grid signal to obtain a two-phase orthogonal signal. Specifically, the following formula can be used:

[0069]

[0070] Among them, V α and V β are two signals in the two-phase orthogonal signal, V m is the amplitude of the input signal, V a 、V b 、V c are the a-phase, b-phase and c-phase signals of the three-phase power grid signal.

[0071] Step S12, filtering out the high-order harmonics and DC components in the two-phase orthogonal signal to obtain a filtered orthogonal signal.

[0072] This step can use two third-order generalized integrators (TOGI) to filter out the 11th-order high-order harmonics and DC components in the two-phase orthogonal signals, and the output of each TOGI module is a set of orthogonal signals. In this step, the filtered orthogonal signals include two sets of orthogonal signals, one set of orthogonal signals is recorded as e αo1 and e qαo1 , and the other set of orthogonal signals is denoted as e βo1 and e qβo1 The transfer function used by the TOGI module is:

[0073]

[0074] Among them, D SOGI , Q SOGI are the two transfer functions used by the TOGI module, s is the variable in the frequency domain, ω is the fundamental angular frequency, k is the damping coefficient, considering the filtering performance and dynamic response capability, k is selected as 1.414 in practical applications; V o (s) and qV o (s) are two orthogonal signals output by the TOGI module, with equal amplitude and 90° phase difference, V i (s) is the input signal of the TOGI module.

[0075] Step S13, performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal. Specifically, the following formula may be used:

[0076]

[0077] Among them, e αo1 、e qαo1 、e βo1 、e qβo1 are the four signal components in the filtered orthogonal signal, e qαo1 With e αo1 Orthogonal, e qβo1 With e βo1 Orthogonal; are the four signal components in the first compensated signal; ω is the fundamental angular frequency, k is the damping coefficient; ω r is the real-time angular frequency of the power grid.

[0078] Here, k and ω are fixed parameters of TOGI. According to the real-time angular frequency obtained by the grid phase-locked loop module, when ω = ω r That is, when the grid frequency does not fluctuate, the TOGI output remains unchanged; when ω≠ω rThat is, when the grid frequency fluctuates, TOGI can compensate for the output amplitude error caused by the frequency fluctuation based on the orthogonal feedforward amplitude compensation module, maintain the original filtering performance, and complete frequency adaptive adjustment of TOGI's output. Figure 2 The schematic diagram of quadrature feedforward amplitude compensation is shown.

[0079] Step S14, performing positive-sequence separation on the first compensated signal to obtain a positive-sequence component. Figure 3 The schematic diagram of positive and negative sequence separation is shown. Specifically, the following formula can be used:

[0080]

[0081] in, are four signal components in the first compensated signal; and are the two signal components of the positive sequence component.

[0082] This step can obtain the positive sequence component when performing positive and negative sequence separation and negative sequence component Only the positive sequence components are used in the subsequent steps

[0083] Step S15, performing Park transformation on the positive sequence component, converting the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtaining a signal after Park transformation.

[0084] In this step, since TOGI has a strong ability to filter out higher harmonics above the 11th order, but a weak ability to filter out lower harmonics of the 5th and 7th orders, the 5th and 7th order harmonic components in the signal are converted into the 6th order harmonic in the dq coordinate system using Park transformation.

[0085] Step S16, tracking the sixth harmonic in the signal after Park transformation and performing orthogonal feedforward amplitude compensation to obtain a second compensated signal.

[0086] Specifically, the sixth harmonic in the signal after Park transformation is tracked to obtain the tracked signal. Here, two SOGI modules are introduced after Park transformation, and the ω parameter is set to 6 times the fundamental frequency. Then the SOGI module can track the sixth harmonic without static error, and further eliminate the sixth harmonic by subtracting it from the original signal, thereby optimizing the insufficient ability of TOGI to eliminate the fifth and seventh harmonics.

[0087] The tracking process implemented by the SOGI module uses the transfer function:

[0088]

[0089] Among them, D SOGI , QSOGI are two transfer functions used for the two signal components of the Park transformed signal in the tracking process, s is a variable in the frequency domain, ω' is the sixth angular frequency of the fundamental wave, and k is the damping coefficient;

[0090] Considering that the performance of SOGI will also be affected by frequency fluctuations, an orthogonal feedforward amplitude compensation module is introduced afterwards. The frequency of the phase-locked loop output is used to adjust the filtering performance and perform orthogonal feedforward amplitude compensation on the tracked signal. The following formula is used:

[0091]

[0092] Among them, e αo 、e βo are the two signal components of the signal after tracking; are the two signal components of the second compensated signal, ω is the fundamental angular frequency, ω r is the real-time angular frequency of the power grid.

[0093] In this step, each SOGI module outputs a set of orthogonal signals, and the orthogonal feedforward amplitude compensation operation only uses one signal in the set of orthogonal signals, that is, the input of the orthogonal feedforward amplitude compensation operation is a signal output by two SOGI modules respectively. αo 、e βo .

[0094] When the frequency is constant, the SOGI output is not compensated; when the frequency changes, SOGI completes the frequency adaptive compensation of the output based on the orthogonal feedforward compensation module.

[0095] Step S17, the Park transformed signal is subtracted from the second compensated signal to eliminate the sixth harmonic, thereby obtaining a final filtered signal.

[0096] Step S18, performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal.

[0097] Step S19, subtract the two-phase orthogonal signal from the signal after inverse Park transformation to obtain a harmonic signal. Here, the harmonic signal includes two signals, which are recorded as the first harmonic signal V hα and the second harmonic signal V hβ .

[0098] The DC component of the dq coordinate system is converted into the fundamental component through the inverse Park transform. At this time, the output signal eliminates the harmonic signal, DC signal and three-phase unbalanced signal through the above-mentioned links, and only contains the fundamental signal. The harmonic detection based on the adaptive generalized integrator can be completed by subtracting the two-phase orthogonal signal from the fundamental signal.

[0099] The present application also provides a method for controlling power grid harmonics using an adaptive generalized integrator. Figure 4 The schematic diagram of the grid harmonic control method using an adaptive generalized integrator is shown in FIG. Figure 4 , methods include:

[0100] Step S41, feedback control is performed on the first harmonic signal to obtain a first feedback-controlled signal; feedback control is performed on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained according to the power grid harmonic detection method of the adaptive generalized integrator of the aforementioned embodiment.

[0101] Here, the first harmonic signal is subtracted from the first control signal to obtain the first feedback-controlled signal; and the second harmonic signal is subtracted from the second control signal to obtain the second feedback-controlled signal.

[0102] Step S42, performing multi-control-level tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, and each control level obtains the signal after the first tracking compensation and the signal after the second tracking compensation.

[0103] Here, the tracking and orthogonal feedforward amplitude compensation of multiple control stages is specifically implemented by multiple tracking and orthogonal feedforward amplitude compensation units (FA-SOGI), and each tracking and orthogonal feedforward amplitude compensation unit (FA-SOGI) outputs a first tracking compensated signal and a second tracking compensated signal. The selection coefficient k is introduced in each control stage. i , k i ∈[0,1]. When k i =1, the level fully tracks the harmonics; when k i =0.5, this stage tracks the harmonic part; k i =0, the stage does not track harmonics.

[0104] Specifically, the closed-loop transfer function used for tracking is:

[0105]

[0106] Among them, H SOGI is the closed-loop transfer function, k s is the proportional control coefficient, ω c is the cutoff angular frequency, s is the variable in the frequency domain, and ω is the fundamental angular frequency.

[0107] After the orthogonal feedforward amplitude compensation, the first tracking compensated signal and the second tracking compensated signal are obtained using the following formula:

[0108]

[0109] in, is the signal after the first tracking compensation, is the signal after the second tracking compensation, u αo is the signal after the first feedback control, u βo is the signal after the second feedback control, ω is the fundamental angular frequency, ω g is the angular frequency of the power grid, ω c is the cut-off angular frequency, and k is the damping coefficient.

[0110] When the grid frequency does not change, that is, ω=ω g ,but The closed-loop transfer function output remains stable; when the grid frequency changes, ω≠ω g , then there is an amplitude error in the closed-loop transfer function output. An orthogonal feedforward compensation branch is introduced after the closed-loop transfer function, and the calculation method of the above formula is used to complete the open-loop frequency adaptive adjustment of SOGI control, thereby realizing harmonic control based on adaptive generalized integrator.

[0111] Step S43, proportional control is performed on the signal after the first feedback control to obtain a first proportionally controlled signal; proportional control is performed on the signal after the second feedback control to obtain a second proportionally controlled signal. Here, the purpose of proportional control is to quickly track the signal.

[0112] Step S44, the signal after the first proportional control is accumulated with the signal after the first tracking compensation corresponding to each control level to obtain a first control signal V αout ; The first control signal is used to perform feedback control on the first harmonic signal.

[0113] Step S45, the signal after the second proportional control is accumulated with the signal after the second tracking compensation corresponding to each control level to obtain a second control signal V βout ; The second control signal is used to perform feedback control on the second harmonic signal.

[0114] Based on the same inventive concept as the power grid harmonic detection method of the adaptive generalized integrator, this embodiment also provides a corresponding power grid harmonic detection device of the adaptive generalized integrator, including:

[0115] Clark transformation module, used to perform Clark transformation on three-phase power grid signals to obtain two-phase orthogonal signals;

[0116] A third-order generalized integrator is used to filter out the high-order harmonics and DC components in the two-phase orthogonal signal to obtain a filtered orthogonal signal;

[0117] An orthogonal feedforward amplitude compensation module, used for performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal;

[0118] A positive-negative sequence separation module, used for performing positive-negative sequence separation on the first compensated signal to obtain a positive-sequence component;

[0119] Park transformation module, used to perform Park transformation on the positive sequence component, convert the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtain the signal after Park transformation;

[0120] A tracking and compensation module is used to track the sixth harmonic in the signal after Park transformation and perform orthogonal feedforward amplitude compensation to obtain a second compensated signal;

[0121] A first subtraction module is used to subtract the Park transformed signal from the second compensated signal to eliminate the sixth harmonic and obtain a final filtered signal;

[0122] An inverse Park transform module, used for performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal;

[0123] The second subtraction module is used to subtract the two-phase orthogonal signal from the signal after inverse Park transformation to obtain a harmonic signal.

[0124] The power grid harmonic detection device of the adaptive generalized integrator of this embodiment has the same inventive concept as the power grid harmonic detection method of the adaptive generalized integrator mentioned above. Therefore, the specific implementation method of the device can be seen in the implementation example part of the power grid harmonic detection method of the adaptive generalized integrator mentioned above, and its technical effect corresponds to the technical effect of the above method, which will not be repeated here.

[0125] Based on the same inventive concept as the power grid harmonic control method of the adaptive generalized integrator, this embodiment also provides a corresponding power grid harmonic control device of the adaptive generalized integrator, including:

[0126] A feedback control module, used for performing feedback control on the first harmonic signal to obtain a first feedback-controlled signal; performing feedback control on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained according to the power grid harmonic detection method of the adaptive generalized integrator of the above-mentioned embodiment;

[0127] A multi-level tracking and compensation module, used for performing multi-control-level tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, wherein each control level corresponds to obtaining the signal after the first tracking compensation and the signal after the second tracking compensation;

[0128] A proportional control module, used to perform proportional control on the signal after the first feedback control to obtain a first proportionally controlled signal; and perform proportional control on the signal after the second feedback control to obtain a second proportionally controlled signal;

[0129] An accumulation module is used to accumulate the signal after the first proportional control and the signal after the first tracking compensation corresponding to each control level to obtain a first control signal; the first control signal is used to perform feedback control on the first harmonic signal; the signal after the second proportional control and the signal after the second tracking compensation corresponding to each control level are accumulated to obtain a second control signal; the second control signal is used to perform feedback control on the second harmonic signal.

[0130] The grid harmonic control device of the adaptive generalized integrator of this embodiment has the same inventive concept as the grid harmonic control method of the adaptive generalized integrator mentioned above, so the specific implementation method of the device can be seen in the implementation example part of the grid harmonic control method of the adaptive generalized integrator mentioned above, and its technical effect corresponds to the technical effect of the above method, which will not be repeated here.

[0131] In order to further verify the application effect of the harmonic detection and control method based on generalized integration of the present application, an active filter control model with a three-level inverter as the main circuit is established. Figure 5 The schematic diagram of the active power filter detection and control system model is shown in Table 1. The main circuit parameters are shown in Table 1:

[0132] Table 1 Main circuit parameters

[0133] Parameter name Parameter Value Parameter name Parameter Value <![CDATA[DC-side reference voltage U dc / V]]> 800 AC inductance measurement L / mH 8 DC side capacitance C / μF 6000 Damping resistance R / Ω 0.5 <![CDATA[Sampling frequency f s / kHz]]> 15 <![CDATA[Switching frequency f sw / kHz]]> 10

[0134] The control module consists of a harmonic detection structure based on an adaptive generalized integrator and a harmonic control structure based on an adaptive generalized integrator. By collecting grid signals, the signals are input into the harmonic detection module, which calculates the harmonic signals to be compensated, and inputs the harmonic signals to be tracked into the controller to achieve zero-static-error tracking control of harmonics. The harmonic output of the control generates a switch signal to drive the main circuit through a PWM generator, and finally controls the conduction of the main circuit switch tube to generate harmonic current for the main circuit output compensation.

[0135] Figure 6 The waveforms of the grid signal, filtered output signal and detected output harmonic signal under different working conditions are shown. The results show that the output fundamental signal of the designed detection module is not disturbed by complex working conditions, the output signal remains unchanged and the waveform quality is high. Accurate detection of harmonic signals can be achieved by subtracting the current from the original sampling point.

[0136] Figure 7The harmonic current and spectrum of the harmonic control structure output by the adaptive generalized integrator under two harmonic conditions of different frequencies are shown, where (a) is the harmonic current and spectrum without tracking control under the 49Hz high distortion rate condition, (b) is the current and spectrum after tracking control of harmonic treatment under the 49Hz high distortion rate condition, (c) is the harmonic current and spectrum without tracking control under the 51Hz low distortion rate condition, and (d) is the current and spectrum after tracking control of harmonic treatment under the 51Hz low distortion rate condition. The results show that the controller can track different harmonic signals, and can achieve tracking control of the harmonics to be compensated under different frequency conditions, and achieve harmonic treatment at the sampling point.

[0137] In summary, this application has the following technical effects:

[0138] 1. Based on the filtering characteristics and frequency selection characteristics of the generalized integrator, the output change of the generalized integrator under the frequency change condition is derived. By constructing the orthogonal signal of the power grid, an adaptive generalized integrator structure with an orthogonal feedforward compensation branch is designed. The compensation error can be calculated according to the power grid frequency and the orthogonal signal, and the adaptive adjustment of the generalized integrator output is completed to ensure the filtering effect and frequency selection accuracy.

[0139] 2. Based on the filtering characteristics, a hybrid filtering structure integrating two kinds of adaptive generalized integrators is designed, in which an adaptive third-order generalized integrator is used as a pre-filter to eliminate the high-order harmonics and DC components of the power grid, and the positive-negative sequence separation module is used to extract the positive sequence components of the power grid under unbalanced power grid conditions. An adaptive second-order generalized integrator is used as a loop filter to further eliminate the 5th and 7th low-order harmonics. The constructed hybrid filtering structure has better harmonic detection capability and dynamic response speed, and the pre-filter can completely eliminate the coupling effect on the loop filter, so that the parameters of the two adaptive generalized integrators can be adjusted independently;

[0140] 3. Based on the frequency selection characteristics, a harmonic current control method of a multi-stage parallel adaptive second-order generalized integrator is designed. By adjusting the coefficient of the single-stage controller, the harmonic signal can be selectively controlled without static error to meet the tracking or compensation requirements under different harmonic conditions. The designed method has application under frequency fluctuation conditions, and can stably detect harmonics and control harmonic signals under the disturbance of three-phase imbalance and DC bias, and has universality in inverter control.

[0141] The above are only various implementations of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for detecting harmonics in a power grid using an adaptive generalized integrator, characterized in that: include: Perform Clark transformation on the three-phase power grid signal to obtain a two-phase orthogonal signal; filtering out the higher harmonics and direct current components in the two-phase orthogonal signal to obtain a filtered orthogonal signal; Performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal; performing positive-sequence and negative-sequence separation on the first compensated signal to obtain a positive-sequence component; Performing Park transformation on the positive sequence component, converting the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtaining a signal after Park transformation; Tracking and performing orthogonal feedforward amplitude compensation on the sixth harmonic in the Park transformed signal to obtain a second compensated signal; Subtracting the Park transformed signal from the second compensated signal to eliminate the sixth harmonic to obtain a final filtered signal; Performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal; The two-phase orthogonal signal is subtracted from the signal after the inverse Park transformation to obtain a harmonic signal.

2. The method according to claim 1, characterized in that in, The orthogonal feedforward amplitude compensation is performed on the filtered orthogonal signal to obtain a first compensated signal using the following formula: Among them, e αo1 、e qαo1 、e βo1 、e qβo1 are the four signal components in the filtered orthogonal signal, e qαo1 With e αo1 Orthogonal, e qβo1 With e βo1 Orthogonal; are the four signal components in the first compensated signal; ω is the fundamental angular frequency, k is the damping coefficient; ω r is the real-time angular frequency of the power grid.

3. The method according to claim 1, characterized in that in, Performing positive and negative sequence separation on the first compensated signal to obtain a positive sequence component includes: in, are four signal components in the first compensated signal; and are the two signal components of the positive sequence component.

4. The method according to claim 1, characterized in that in, Tracking the sixth harmonic in the Park transformed signal and performing orthogonal feedforward amplitude compensation to obtain a second compensated signal, including: The sixth harmonic in the Park transformed signal is tracked to obtain a tracked signal, and the adopted transfer function is: Among them, D SOGI , Q SOGI are two transfer functions used for the two signal components of the Park transformed signal in the tracking process, s is a variable in the frequency domain, ω' is the sixth angular frequency of the fundamental wave, and k is the damping coefficient; The orthogonal feedforward amplitude compensation is performed on the tracked signal using the following formula: Among them, e αo 、e βo are the two signal components of the signal after tracking; are the two signal components of the second compensated signal; ω is the fundamental angular frequency, ω r is the real-time angular frequency of the power grid.

5. A method for controlling power grid harmonics using an adaptive generalized integrator, characterized in that: include: Performing feedback control on the first harmonic signal to obtain a signal after first feedback control; Feedback control is performed on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained by the power grid harmonic detection method of the adaptive generalized integrator according to any one of claims 1 to 4; Performing multi-control-level tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, and obtaining the first tracking-compensated signal and the second tracking-compensated signal corresponding to each control level; Performing proportional control on the signal after the first feedback control to obtain a first proportionally controlled signal; Performing proportional control on the signal after the second feedback control to obtain a second proportionally controlled signal; The signal after the first proportional control is accumulated with the signal after the first tracking compensation corresponding to each control level to obtain a first control signal; The first control signal is used to perform feedback control on the first harmonic signal; The signal after the second proportional control is accumulated with the signal after the second tracking compensation corresponding to each control stage to obtain a second control signal; the second control signal is used to perform feedback control on the second harmonic signal.

6. The method according to claim 5, characterized in that The closed-loop transfer function used in the tracking is: Among them, H SOGI is the closed-loop transfer function, k s is the proportional control coefficient, ω c is the cutoff angular frequency, s is the variable in the frequency domain, and ω is the fundamental angular frequency.

7. The method according to claim 5, characterized in that The signal after the first tracking compensation and the signal after the second tracking compensation are expressed by the following formula: in, is the signal after the first tracking compensation, is the signal after the second tracking compensation, u αo is the signal after the first feedback control, u βo is the signal after the second feedback control, ω is the fundamental angular frequency, ω g is the angular frequency of the power grid, ω c is the cut-off angular frequency, and k is the damping coefficient.

8. A power grid harmonic detection device using an adaptive generalized integrator, characterized in that: include: Clark transformation module, used to perform Clark transformation on three-phase power grid signals to obtain two-phase orthogonal signals; A third-order generalized integrator is used to filter out the higher harmonics and DC components in the two-phase orthogonal signal to obtain a filtered orthogonal signal; An orthogonal feedforward amplitude compensation module, used for performing orthogonal feedforward amplitude compensation on the filtered orthogonal signal to obtain a first compensated signal; A positive-negative sequence separation module, used for performing positive-negative sequence separation on the first compensated signal to obtain a positive-sequence component; A Park transformation module, used for performing Park transformation on the positive sequence component, converting the 5th and 7th harmonic components in the positive sequence component into the 6th harmonic in the dq coordinate system, and obtaining a signal after Park transformation; A tracking and compensation module, used for tracking the sixth harmonic in the signal after Park transformation and performing orthogonal feedforward amplitude compensation to obtain a second compensated signal; A first subtraction module, used for subtracting the Park transformed signal from the second compensated signal to eliminate the sixth harmonic and obtain a final filtered signal; An inverse Park transform module, used for performing an inverse Park transform on the final filtered signal to obtain an inverse Park transformed signal; The second subtraction module is used to subtract the two-phase orthogonal signal from the signal after the inverse Park transformation to obtain a harmonic signal.

9. A power grid harmonic control device using an adaptive generalized integrator, characterized in that: include: A feedback control module, used for performing feedback control on the first harmonic signal to obtain a signal after first feedback control; Feedback control is performed on the second harmonic signal to obtain a second feedback-controlled signal; the first harmonic signal and the second harmonic signal are obtained by the power grid harmonic detection method of the adaptive generalized integrator according to any one of claims 1 to 4; A multi-stage tracking and compensation module, used for performing multi-control-stage tracking and orthogonal feedforward amplitude compensation on the signal after the first feedback control and the signal after the second feedback control, wherein each control stage corresponds to obtaining the signal after the first tracking compensation and the signal after the second tracking compensation; A proportional control module, used for performing proportional control on the signal after the first feedback control to obtain a first proportionally controlled signal; Performing proportional control on the signal after the second feedback control to obtain a second proportionally controlled signal; An accumulation module, used for accumulating the signal after the first proportional control and the signal after the first tracking compensation corresponding to each control level to obtain a first control signal; The first control signal is used to perform feedback control on the first harmonic signal; The signal after the second proportional control is accumulated with the signal after the second tracking compensation corresponding to each control stage to obtain a second control signal; The second control signal is used to perform feedback control on the second harmonic signal.

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