Three-phase voltage and current signal positive and negative zero sequence decomposition method and system based on Hilbert-Huang transform, storage medium and processor

Abstract

The invention relates to the technical field of power systems, in particular to a three-phase voltage and current signal positive and negative zero sequence decomposition method and system based on Hilbert-Huang transform, a storage medium and a processor. Starting from original data of three-phase voltage / current signals, complex signal information of the three-phase voltage / current signals is obtained through Hilbert-Huang transform, and all frequency information of the original signals is reserved to the maximum extent through the Hilbert-Huang transform. Based on original definitions of positive and negative sequence signals, a positive and negative zero sequence signal component is obtained by multiplying a complex signal vector by a positive and negative zero sequence decomposition transformation matrix T, so that the accuracy of positive and negative zero sequence decomposition can be ensured. By performing Hilbert-Huang transform on three-phase voltage and current signals, effective decomposition of positive-sequence, negative-sequence and zero-sequence components can be realized. According to the invention, the capability of identifying fault signals is improved, and accurate data support is provided for stable control of power electronic equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method, system, storage medium and processor for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform. Background Art

[0002] As the global "dual carbon" goal becomes increasingly prominent, promoting the transformation of energy structure and the widespread application of renewable energy has become an important strategy for all countries. As the core of energy conversion and transmission, the safe, stable and efficient operation of the power system directly affects the integration and utilization of renewable energy. With the rapid development of power electronics technology, more and more power electronic equipment are introduced into the power system, such as inverters, flexible DC transmission equipment and power quality control devices. These devices can not only improve the flexibility and controllability of the power system, but also realize the dynamic management of power quality, thus providing strong support for promoting the high proportion of renewable energy grid connection. However, the demand for control of power electronic equipment in the power system is also increasing. In order to achieve efficient and stable control, it is necessary to monitor and analyze the various operating states of the power system in real time. Especially in the case of a fault in the power system, the control strategy needs to be able to respond quickly to ensure the stability and safety of the system. Therefore, it is particularly important to accurately analyze and process the voltage and current signals in the power system.

[0003] In power systems, asymmetric faults such as single-phase short circuits are not uncommon. Such faults not only affect the normal operation of the power system, but also pose a potential threat to the safety of the equipment. During the fault occurrence and recovery process, asymmetric voltage and current will appear in the system. This asymmetry poses a challenge to traditional signal processing methods, because traditional methods are usually unable to accurately distinguish and extract the positive sequence components and negative sequence components in the signal. In order to achieve stable control of power electronic equipment, it is necessary to accurately extract positive sequence signals and negative sequence signals from three-phase voltage and current signals. The positive sequence signal reflects the characteristics of the power system under normal operation, while the negative sequence signal is used to characterize the impact of asymmetric faults on the system.

[0004] In the prior art, positive and negative zero sequence decomposition is mostly based on phase-locked loops and filters, and the positive and negative sequence dq axis component signals are decomposed by low-pass filters. The positive and negative sequence components in the actual three-phase signal are coupled together, and the positive and negative sequence components cannot be accurately obtained by low-pass filters. In addition, there is a phase delay in the low-pass filter, which further increases the measurement error. Summary of the invention

[0005] In view of the problems in the prior art, the present invention provides a method, system, storage medium and processor for decomposing the positive and negative zero sequence of three-phase voltage and current signals based on Hilbert-Huang transform. Hilbert-Huang transform is a powerful signal processing tool that can effectively separate different frequency components in the signal and provide information about the instantaneous frequency and envelope of the signal. The specific technical solution is as follows:

[0006] A method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform comprises the following steps: Step S1, collecting three-phase voltage / current measurement signals v of a power electronic device grid connection point a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, v c It is the C phase voltage / current measurement signal;

[0007] Step S2, measuring the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c is the complex signal of phase C voltage / current;

[0008] Step S3: convert the three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal V n and zero-sequence voltage / current complex signal V o ; Step S4, the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal V n Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment;

[0009] Step S5, complex processing of positive sequence voltage / current signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn .

[0010] Preferably, the Hilbert-Huang transform in step S2 is specifically performed as follows:

[0011] Step S21, using the fast Fourier algorithm to calculate v i Frequency domain of the signal The specific expressions are as follows:

[0012]

[0013] Among them, v i represents the voltage / current measurement signal of the i-th phase, FFT(*) represents the fast Fourier transform calculation, v i [n] represents a set of v in the fast Fourier calculation time window i Signal, n represents the number of this set of data, n is an even number;

[0014] Step S22, create a Frequency domain arrays of the same size make express The kth data, express The kth data, then:

[0015]

[0016] Step S23, calculate the inverse Fourier transform to obtain the Hilbert transform signal

[0017]

[0018] Where IFFT(*) represents the inverse fast Fourier transform calculation;

[0019] Step S24, constructing the i-th phase voltage complex signal V i for:

[0020]

[0021] Preferably, the calculation formula in step S3 is:

[0022]

[0023] Preferably, the positive and negative zero-sequence decomposition transformation matrix T is as follows:

[0024]

[0025] Preferably, the calculation formula in step S4 is:

[0026]

[0027] Preferably, the synchronous control loop in step S4 is a phase-locked loop or a virtual synchronous control loop.

[0028] Preferably, the calculation formula in step S5 is:

[0029]

[0030] Among them, Real[*] means taking the real part, and Imag[*] means taking the imaginary part.

[0031] A decomposition system of positive and negative zero sequence of three-phase voltage and current signals based on Hilbert-Huang transform, applied to the method, comprises:

[0032] Acquisition module, used to collect three-phase voltage / current measurement signals v of power electronic equipment grid connection points a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, v c It is the C phase voltage / current measurement signal;

[0033] Hilbert-Huang transform module is used to measure the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c is the complex signal of phase C voltage / current;

[0034] Decomposition module, used to convert three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal Vn and zero-sequence voltage / current complex signal V o ;

[0035] The first processing module is used to process the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal V n Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment;

[0036] The second processing module is used to process the positive sequence voltage / current complex signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn .

[0037] A computer-readable storage medium includes a stored program, wherein when the program is run, the device where the computer-readable storage medium is located is controlled to execute the method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform.

[0038] A processor is used to run a program, wherein the program executes the decomposition method of positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform when running.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention starts from the original data of the three-phase voltage / current signal, and first obtains the complex signal information of the three-phase voltage / current signal respectively through the Hilbert-Huang transform, and the Hilbert-Huang transform retains all the frequency information of the original signal to the greatest extent. Then, based on the original definition of the positive and negative sequence signals, the positive and negative zero sequence signal components are obtained by multiplying the complex signal vector by the positive and negative zero sequence decomposition transformation matrix T, which can ensure the accuracy of the positive and negative zero sequence decomposition. By performing the Hilbert-Huang transform on the three-phase voltage and current signals, the positive sequence, negative sequence and zero sequence components can be effectively decomposed. The present invention not only improves the ability to identify fault signals, but also provides accurate data support for the stable control of power electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0042] Figure 1 It is a schematic diagram of the principle of the method of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0045] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0046] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0047] Embodiment 1:

[0048] like Figure 1 As shown, this embodiment provides a method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform, comprising the following steps:

[0049] Step S1, collecting the three-phase voltage / current measurement signal v of the power electronic equipment grid connection point a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, vc It is the C phase voltage / current measurement signal.

[0050] Step S2, measuring the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c It is the complex signal of phase C voltage / current.

[0051] The Hilbert-Huang transform is as follows:

[0052] Step S21, using the fast Fourier algorithm to calculate v i Frequency domain of the signal The specific expressions are as follows:

[0053]

[0054] Among them, v i represents the voltage / current measurement signal of the i-th phase, FFT(*) represents the fast Fourier transform calculation, v i [n] represents a set of v in the fast Fourier calculation time window i Signal, n represents the number of this set of data, n is an even number;

[0055] Step S22, create a Frequency domain arrays of the same size make express The kth data, express The kth data, then:

[0056]

[0057] Step S23, calculate the inverse Fourier transform to obtain the Hilbert transform signal

[0058]

[0059] Where IFFT(*) represents the inverse fast Fourier transform calculation;

[0060] Step S24, constructing the i-th phase voltage complex signal V i for:

[0061]

[0062] Step S3: convert the three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal V n and zero-sequence voltage / current complex signal V o The calculation formula is:

[0063]

[0064] The positive and negative zero-sequence decomposition transformation matrix T is as follows:

[0065]

[0066] Step S4: the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal V n Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment, where the synchronous control loop is a phase-locked loop or a virtual synchronous control loop. The calculation formula is:

[0067]

[0068] Step S5, complex processing of positive sequence voltage / current signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn The calculation formula is:

[0069]

[0070] Among them, Real[*] means taking the real part, and Imag[*] means taking the imaginary part.

[0071] The present invention starts from the original data of the three-phase voltage / current signal, and first obtains the complex signal information of the three-phase voltage / current signal respectively through the Hilbert-Huang transform, and the Hilbert-Huang transform retains all the frequency information of the original signal to the greatest extent. Then, based on the original definition of the positive and negative sequence signals, the positive and negative zero sequence signal components are obtained by multiplying the complex signal vector by the positive and negative zero sequence decomposition transformation matrix T, which can ensure the accuracy of the positive and negative zero sequence decomposition.

[0072] Embodiment 2:

[0073] Based on the same inventive concept as that of Embodiment 1, this embodiment provides a decomposition system of positive and negative zero sequence of three-phase voltage and current signals based on Hilbert-Huang transform, which is applied to the method described, including:

[0074] Acquisition module, used to collect three-phase voltage / current measurement signals v of power electronic equipment grid connection points a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, v c It is the C phase voltage / current measurement signal;

[0075] Hilbert-Huang transform module is used to measure the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c is the complex signal of phase C voltage / current;

[0076] Decomposition module, used to convert three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal V n and zero-sequence voltage / current complex signal V o ;

[0077] The first processing module is used to process the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal Vn Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment;

[0078] The second processing module is used to process the positive sequence voltage / current complex signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn .

[0079] Embodiment 3:

[0080] Based on the same inventive concept as Example 1, this embodiment provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the method for decomposing the positive and negative zero sequence of the three-phase voltage and current signals based on the Hilbert-Huang transform.

[0081] Embodiment 4:

[0082] Based on the same inventive concept as that of Example 1, this embodiment provides a processor, which is used to run a program, wherein the program executes the method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform when running.

[0083] Those of ordinary skill in the art will appreciate that the modules of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0084] In the embodiments provided by the present invention, it should be understood that the division of modules is only a logical function division, and there may be other division methods in actual implementation, for example, multiple modules can be combined into one module, one module can be split into multiple modules, or some features can be ignored, etc.

[0085] In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of software functional modules.

[0086] If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-0nlyMemory), random access memory (RAM, RandomAccessMemory), mobile hard disk, magnetic disk or optical disk, etc., various media that can store program codes.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform, characterized in that: The following steps are involved: Step S1, collecting the three-phase voltage / current measurement signal v of the power electronic equipment grid connection point a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, v c It is the C phase voltage / current measurement signal; Step S2, measuring the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c is the complex signal of phase C voltage / current; Step S3: convert the three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal V n and zero-sequence voltage / current complex signal V o ; Step S4: the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal V n Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment; Step S5, complex processing of positive sequence voltage / current signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn .

2. The method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1, characterized in that: The Hilbert-Huang transform in step S2 is specifically performed as follows: Step S21, using the fast Fourier algorithm to calculate v i Frequency domain of the signal The specific expressions are as follows: Among them, v i represents the voltage / current measurement signal of the i-th phase, FFT(*) represents the fast Fourier transform calculation, v i [n] represents a set of v in the fast Fourier calculation time window i Signal, n represents the number of this set of data, n is an even number; Step S22, create a Frequency domain arrays of the same size make express The kth data, express The kth data: Step S23, calculate the inverse Fourier transform to obtain the Hilbert transform signal Where IFFT(*) represents the inverse fast Fourier transform calculation; Step S24, constructing the i-th phase voltage complex signal V i for:

3. The method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1, characterized in that: The calculation formula in step S3 is:

4. A method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1 or 3, characterized in that: The positive and negative zero-sequence decomposition transformation matrix T is as follows:

5. The method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1, characterized in that: The calculation formula in step S4 is:

6. The method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1, characterized in that: The synchronous control loop in step S4 is a phase-locked loop or a virtual synchronous control loop.

7. The method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform according to claim 1, characterized in that: The calculation formula in step S5 is: Among them, Real[*] means taking the real part, and Imag[*] means taking the imaginary part.

8. A decomposition system of positive and negative zero sequence of three-phase voltage and current signals based on Hilbert-Huang transform, characterized in that: The method applied to any one of claims 1 to 7, comprising: Acquisition module, used to collect three-phase voltage / current measurement signals v of power electronic equipment grid connection points a 、v b 、v c , where v a is the A phase voltage / current measurement signal, v b is the B phase voltage / current measurement signal, v c It is the C phase voltage / current measurement signal; Hilbert-Huang transform module is used to measure the three-phase voltage / current signal v a 、v b 、v c Perform Hilbert-Huang transform respectively to obtain the three-phase voltage / current complex signal V a 、V b 、V c ; where V a is the complex voltage / current signal of phase A, V b is the complex voltage / current signal of phase B, V c is the complex signal of phase C voltage / current; Decomposition module, used to convert three-phase voltage / current complex signal V a 、V b 、V c The vector is multiplied by the positive and negative zero sequence decomposition transformation matrix T to obtain the positive sequence voltage / current complex signal V p , Negative sequence voltage / current complex signal V n and zero-sequence voltage / current complex signal V o ; The first processing module is used to process the positive sequence voltage / current complex signal V p Multiply Get the positive sequence voltage / current complex processing signal For the negative sequence voltage / current complex signal V n Multiply Get the negative sequence voltage / current complex processing signal where θ pll It is the synchronous phase output by the synchronous control loop in the power electronic equipment; The second processing module is used to process the positive sequence voltage / current complex signal Take the real part to get the positive sequence d-axis voltage / current v dp , take the imaginary part to get the positive sequence q-axis voltage / current v qp ; Complex processing signal for negative sequence voltage / current Take the real part to get the negative sequence d-axis voltage / current v dn , take the imaginary part to get the negative sequence q axis voltage / current v qn .

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for decomposing the positive and negative zero sequence of three-phase voltage and current signals based on Hilbert-Huang transform as described in any one of claims 1 to 7.

10. A processor, characterized in that: The processor is used to run a program, wherein the program, when running, executes the method for decomposing positive and negative zero sequences of three-phase voltage and current signals based on Hilbert-Huang transform as described in any one of claims 1 to 7.

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