A resonance detection method and device for a new energy power system

Abstract

The present invention provides a resonance detection method and device for a new energy power system, and relates to the field of new energy technology. The method comprises: performing wavelet packet transformation on a grid-connected voltage signal according to a preset filter group to obtain a plurality of sub-bands sorted in order of frequency magnitude, and extracting a sub-band with the largest signal fluctuation amplitude from the plurality of sub-bands as a target sub-band where a resonance signal is located; performing waveform matching on a characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the direction of the endpoints respectively; analyzing the extended signal to obtain the resonance frequency and amplitude of the new energy power generation grid-connected system. The device executes the above method. The resonance detection method and device for a new energy power system provided in an embodiment of the present invention can effectively determine the resonance frequency and improve the detection speed and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a resonance detection method and device for a new energy power system. Background Art

[0002] In recent years, with the widespread access to variable-power sources such as wind power and photovoltaics, some resonance problems have emerged. The interaction between adjacent converters and the interaction between multiple converters and the power grid will lead to resonance problems in new energy power systems, seriously threatening the safe and stable operation of the power system. Therefore, it is of great significance to carry out research on resonance detection methods for new energy power systems.

[0003] The frequency bands obtained by the existing wavelet packet decomposition are not distributed according to the frequency size, and the resonant frequency range cannot be directly determined according to the result of the wavelet packet decomposition, which is not conducive to resonance detection. Summary of the invention

[0004] In view of the problems in the prior art, an embodiment of the present invention provides a resonance detection method and device for a new energy power system, which can at least partially solve the problems in the prior art.

[0005] On the one hand, the present invention provides a resonance detection method for a new energy power system, comprising:

[0006] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0007] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0008] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0009] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0010] The step of performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform includes:

[0011] The matching waveform is obtained by matching the amplitude, rise time and fall time of the characteristic waveform.

[0012] Wherein, obtaining the preset filter group includes:

[0013] Obtaining the filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence, and marking the filter path with binary digital marks;

[0014] Arrange the marked binary digits in sequence to obtain a digital sequence;

[0015] Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence;

[0016] The arrangement order of the low-pass filter and the high-pass filter is determined according to the values ​​of the updated digital sequence to obtain the preset filter group.

[0017] The step of marking the filter path with binary numbers includes:

[0018] If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0;

[0019] If the grid-connected voltage signal passes through a high-pass filter, the marking number for binary digital marking of the filter path is 1.

[0020] The method of updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position to obtain an updated digital sequence includes:

[0021] If the number of 1s before the position of the currently traversed number is an odd number, negate the value of the currently traversed number;

[0022] If the number of values ​​1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged.

[0023] The step of sequentially traversing each number in the digital sequence and updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes:

[0024] updating the value of the currently traversed number in the digital sequence according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed;

[0025] The numerical processing result includes negating the numerical value of the currently traversed number, or keeping the numerical value of the currently traversed number unchanged.

[0026] On the one hand, the present invention provides a resonance detection device for a new energy power system, comprising:

[0027] An extraction unit is used to perform wavelet packet transformation on the grid-connected voltage signal according to a preset filter group to obtain a plurality of sub-frequency bands sorted in order of frequency magnitude, and extract a sub-frequency band with the largest signal fluctuation amplitude from the plurality of sub-frequency bands as a target sub-frequency band where the resonance signal is located;

[0028] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0029] An extension unit, configured to perform waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and to extend the endpoints on both sides of the matching waveform in the directions of the endpoints;

[0030] The analysis unit is used to analyze the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0031] In another aspect, an embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the following method when executing the computer program:

[0032] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0033] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0034] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0035] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0036] An embodiment of the present invention provides a computer-readable storage medium, including:

[0037] The computer readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0038] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0039] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0040] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0041] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0042] The embodiment of the present invention further provides a computer program product, the computer program product comprising a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0043] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0044] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0045] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0046] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0047] The resonance detection method and device of the new energy power system provided by the embodiment of the present invention perform wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-bands sorted in order of frequency size, and extract the sub-band with the largest signal fluctuation amplitude in the multiple sub-bands as the target sub-band where the resonance signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in sequence in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; waveform matching is performed on the characteristic waveform in the target sub-band to obtain a matching waveform, and the endpoints on both sides of the matching waveform are respectively extended in the direction of the endpoints; the extended signal is analyzed to obtain the resonance frequency and amplitude of the new energy power generation grid-connected system, which can effectively determine the resonance frequency and improve the detection speed and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0049] Figure 1 It is a flow chart of a resonance detection method for a new energy power system provided in one embodiment of the present invention.

[0050] Figure 2 It is a schematic diagram illustrating uniform frequency bands distributed in order of frequency provided by an embodiment of the present invention.

[0051] Figure 3 It is a schematic diagram illustrating the improved adaptive waveform matching extension provided by an embodiment of the present invention.

[0052] Figure 4 It is a schematic diagram illustrating the grid-connected voltage of the new energy power system provided by an embodiment of the present invention.

[0053] Figure 5 It is a schematic diagram illustrating the improved wavelet packet analysis of the grid-connected voltage provided by an embodiment of the present invention.

[0054] Figure 6 It is a schematic diagram illustrating the improved HHT analysis of the sub-band X(5,12) provided by an embodiment of the present invention.

[0055] Figure 7 It is a structural schematic diagram of a resonance detection device for a new energy power system provided by an embodiment of the present invention.

[0056] Figure 8A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0058] Figure 1 FIG. 1 is a flow chart of a resonance detection method for a new energy power system provided by an embodiment of the present invention. Figure 1 As shown, the resonance detection method of the new energy power system provided by the embodiment of the present invention includes:

[0059] Step S1: performing wavelet packet transformation on the grid-connected voltage signal according to a preset filter group to obtain a plurality of sub-frequency bands sorted in order of frequency magnitude, and extracting a sub-frequency band with the largest signal fluctuation amplitude from the plurality of sub-frequency bands as a target sub-frequency band where the resonance signal is located;

[0060] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter.

[0061] Step S2: performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the direction of the endpoints.

[0062] Step S3: Analyze the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0063] In the above step S1, the device performs wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-bands sorted in order of frequency, and extracts the sub-band with the largest signal fluctuation amplitude from the multiple sub-bands as the target sub-band where the resonant signal is located;

[0064] The preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter. The device can be a computer device for executing the method, such as a server. The acquisition, storage, use, and processing of data in the technical solution of this application are in compliance with relevant regulations.

[0065] Let U(t) be the original signal, X (i,j)represents the sub-band, represents the jth wavelet packet coefficient on the i-th layer, (i, j) is the label of each node after the wavelet packet is decomposed, where the letter i represents the decomposition layer number and j represents the order. d and F g are the low-pass and high-pass filter coefficients of wavelet packet decomposition, respectively. k and n represent integers. The wavelet packet decomposition is as follows:

[0066]

[0067] In the formula, F d and F g Determined by the wavelet basis, i∈N, j=0,1,2,3,…,2 i -1.

[0068] Acquiring the preset filter group includes:

[0069] Obtaining the filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence, and marking the filter path with binary digital marks;

[0070] Arrange the marked binary digits in sequence to obtain a digital sequence;

[0071] Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence;

[0072] The arrangement order of the low-pass filter and the high-pass filter is determined according to the values ​​of the updated digital sequence to obtain the preset filter group.

[0073] The step of marking the filter path with binary digital information comprises:

[0074] If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0;

[0075] If the grid-connected voltage signal passes through a high-pass filter, the marking number for binary digital marking of the filter path is 1.

[0076] The method updates the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position, and obtains an updated digital sequence, including:

[0077] If the number of 1s before the position of the currently traversed number is an odd number, negate the value of the currently traversed number;

[0078] If the number of values ​​1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged.

[0079] The method of sequentially traversing each number in the digital sequence and updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes:

[0080] updating the value of the currently traversed number in the digital sequence according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed;

[0081] The numerical processing result includes negating the numerical value of the currently traversed number, or keeping the numerical value of the currently traversed number unchanged.

[0082] The specific instructions are as follows:

[0083] Preset filter banks rearrange the low-pass and high-pass filter banks, including:

[0084] (1) Let the sampling frequency be f s According to Nyquist theorem, the frequency band that wavelet packet decomposition can detect is [0,f s / 2], after a layer of wavelet packet decomposition, the entire frequency band is divided into low-frequency bands [0,f s / 2 2 ] and high frequency band [f s / 2 2 ,f s / 2].

[0085] (2) After the low-frequency signal is down-sampled, it is decomposed into [0, f s / 2 3 ] and [f s / 2 3 ,f s / 2 2 ]Two frequency bands.

[0086] (3) According to the method described in step (2), the decomposition from the third layer to the nth layer is performed in sequence until the set n-layer decomposition is completed, that is, the binary division of the low-frequency band is achieved.

[0087] (4) After the high-frequency signal is down-sampled, it is first converted into a low-frequency signal, and then decomposed through the secondary layer. The high-frequency band is divided into [f s / 2 2 ,f s 3 / 2 3 ] and [f s 3 / 2 3 ,f s / 2] two frequency bands.

[0088] (5) Decomposition from the third layer to the nth layer is performed in sequence in the manner described in step (4) until the set n-layer decomposition is completed, that is, binary division of the high-frequency band is achieved, that is, a uniformly divided frequency band is obtained.

[0089] (6) Uniform frequency bands distributed in order of frequency, such as Figure 2 As shown, the sampling frequency is 6400Hz, s(t) represents the original signal, D and G are wavelet packet decomposition low-pass and high-pass filters respectively. Each node in the wavelet packet tree corresponds to a filter path and a frequency band, wherein the filter path is the filter group that the signal passes through from left to right when it reaches the node, and the frequency band is the frequency range corresponding to the node.

[0090] (7) The path of the signal passing through the low-pass filter is set to '0', and the path of the signal passing through the high-pass filter is set to '1', and the binary number corresponding to the filter path is obtained.

[0091] (8) During the improved wavelet packet transform process, the binary number corresponding to the filter path will be updated. When each digit is taken, the number of 1s in front of the position of the digit is checked from left to right. If it is an odd number, the digit at that position is negated. If it is an even number, the digit at that position remains unchanged.

[0092] (9) After readjusting the arrangement of the low-pass and high-pass filter groups, a new binary number is obtained. The value of the new binary number represents the order of this node, that is, a uniform frequency band distributed according to the frequency size is obtained.

[0093] (10) Extract the frequency band X with the largest amplitude fluctuation, which is the frequency band where the resonance occurs.

[0094] In the above step S2, the device performs waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extends the two end points of the matching waveform in the direction of the end points. The waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform includes:

[0095] The matching waveform is obtained by matching the amplitude, rise time and fall time of the characteristic waveform. Figure 3 As shown,

[0096] The left boundary point of the signal and the corresponding time are O1 and The first maximum value and the corresponding time from the left endpoint are P1 and The first minimum value and the corresponding time are Q1 and Rise time t between characteristic waveforms m1 and the fall time t n1 The characteristic waveform of the waveform matching method is selected as the O1-P1-Q1 triangle wave. The matching waveform is O i -Pi -Q i Triangle wave, matching waveform left boundary point and corresponding time are O i and The first maximum value and the corresponding time from the left endpoint are P i and The first minimum value and the corresponding time are Q i and Matching the rise time t between waveforms mi and the fall time t ni When extending to the left, the data before the matching waveform (when extending to the right, the data after the matching waveform) is used as the waveform extension of the signal, so that the natural trend of the signal can be satisfied.

[0097] The existing waveform matching error only considers the amplitudes of the three points O, P and Q. The waveform matching error algorithm adopted in the embodiment of the present invention also takes into account the waveform depth, the rise and fall time of the waveform, so that the matching waveform will be more accurate and the endpoint effect of HHT is improved.

[0098] Steps of the adaptive waveform matching continuation algorithm:

[0099] a) Calculate the adaptive matching waveform boundary point O i The corresponding time t Oi for:

[0100]

[0101] b) Calculate the matching error δ(i) between the characteristic waveform and the matching waveform, where δ1(i) represents the amplitude error between the waveforms, and δ2(i) is the error in the rise time and fall time between the waveforms.

[0102]

[0103] U1 and U2 are two constants, and their calculation formulas are as follows, where || represents the modulus.

[0104]

[0105] Normalize the matching error with U1 and U2 to get δ2(i) as shown below. Substitute the new δ2(i) into δ(i) to get the normalized matching error as shown below.

[0106]

[0107]

[0108] Find the waveform with the smallest matching error among all matching errors as the final matching waveform.

[0109] c) Select the data waveform before the final matching waveform, i.e., the extended waveform, and extend it to the left end point of the grid-connected voltage signal.

[0110] d) Use the same method to extend the right endpoint of the signal to obtain the extended signal.

[0111] In the above step S3, the device analyzes the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0112] The extended signal is analyzed using HHT, and finally the resonant frequency and amplitude of the new energy power system are obtained.

[0113] a) Let the extended signal be S(t), perform EMD (Empirical Mode Decomposition) on the extended signal S(t) to obtain a finite number of intrinsic mode functions c i and a trend term r, where i is a variable. The intrinsic mode function must satisfy the following two conditions: (1) the number of extreme points is equal to or the difference is one with the number of zero points; (2) the local mean of the upper envelope defined by the maximum value and the lower envelope defined by the minimum value is zero. The signal formula to be analyzed is as follows:

[0114]

[0115] b) For each intrinsic mode function c i Perform Hilbert transform to obtain the instantaneous frequency and instantaneous amplitude of each harmonic, including:

[0116] For each intrinsic mode function c i , perform Hilbert transform to get c i Hilbert transform as follows:

[0117]

[0118] Get the instantaneous amplitude a(t) of the harmonic:

[0119]

[0120] And the phase θ(t) of the harmonics:

[0121]

[0122] And the instantaneous frequency f(t) of the harmonic:

[0123]

[0124] The following is an explanation of the application examples:

[0125] The grid-connected voltage containing resonant signals in the renewable energy power system is analyzed.

[0126] The grid-connected voltage containing resonant signals in the new energy power system is as follows: Figure 4 The grid-connected voltage analysis results of the new energy power system based on the combination of wavelet packet transform and Hilbert Huang transform are shown in Figure 5 shown.

[0127] The sub-bands of the improved wavelet packet transform are distributed in order of frequency size. The sampling frequency is 6400Hz. The frequency range corresponding to the signal of each sub-band is shown in Table 1:

[0128] Table 1

[0129] Sub-band Frequency range / Hz Sub-band Frequency range / Hz Sub-band Frequency range / Hz X(5,0) [0,100] X(5,6) [400,500] X(5,12) [800,900] X(5,1) [100,200] X(5,7) [500,600] X(5,13) [900,1000] X(5,3) [200,300] X(5,5) [600,700] X(5,2) [300,400] X(5,4) [700,800]

[0130] It can be seen that the amplitude fluctuation of X(5,12) is the largest, that is, the sub-band where the resonant signal is located is X(5,4), and its frequency range is [800Hz,900Hz]. HHT analysis is performed on the sub-band X(5,12), and the analysis results are as follows Figure 6 shown.

[0131] Depend on Figure 6 It can be seen that the resonant frequency is 811.43 Hz and the amplitude is 61.02 V. The simulation proves that the resonance detection algorithm based on the combination of improved wavelet packet transform and improved Hilbert-Huang transform can accurately detect the frequency and amplitude of the resonant voltage in the renewable energy power system.

[0132] WPT divides the frequency band into multiple levels, and can divide the frequency band into both the low-frequency part and the high-frequency part, but the obtained sub-bands are not arranged in the order of frequency size. The improved WPT proposed in the present invention obtains sub-bands arranged in the order of frequency size by rearranging the high-pass filter and the low-pass filter combination, thereby improving the detection speed. Compared with traditional harmonic interference, the impact of resonant interference on the system is more serious, and the amplitude fluctuation is more obvious. Therefore, the sub-band with the largest amplitude fluctuation, that is, the frequency band where the resonant signal is located, is extracted, and the next step of analysis is only required for this band.

[0133] HHT has a strong advantage in detecting signal frequency and amplitude, but it has the disadvantage of endpoint effect. The improved HHT proposed in the present invention not only considers the waveform depth, but also takes into account the waveform rise time and waveform fall time on the basis of the existing waveform matching and extension method, so that the matching waveform will be more accurate, improving the endpoint effect of HHT and improving the detection accuracy. Compared with traditional WPT and HHT, the resonance detection method of the new energy power system based on the combination of improved WPT and improved HHT proposed in the present invention can not only effectively determine the amplitude and frequency of the resonance signal, but also improve the detection speed and accuracy.

[0134] The resonance detection method of the new energy power system provided by the embodiment of the present invention performs wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-bands sorted in order of frequency size, and extracts the sub-band with the largest signal fluctuation amplitude in the multiple sub-bands as the target sub-band where the resonance signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in sequence in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; waveform matching is performed on the characteristic waveform in the target sub-band to obtain a matching waveform, and the endpoints on both sides of the matching waveform are respectively extended in the direction of the endpoints; the extended signal is analyzed to obtain the resonance frequency and amplitude of the new energy power generation grid-connected system, which can effectively determine the resonance frequency and improve the detection speed and accuracy.

[0135] Further, performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform includes:

[0136] The matching waveform is obtained by matching the amplitude, rise time and fall time of the characteristic waveform. The above description can be referred to and will not be repeated here.

[0137] Further, obtaining the preset filter group includes:

[0138] The filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence is obtained, and the filter path is marked with binary digitals; the above-mentioned embodiment can be referred to for description and will not be repeated here.

[0139] The marked binary digits are arranged in sequence to obtain a digital sequence; this can be described with reference to the above embodiment and will not be described in detail.

[0140] Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence; refer to the above embodiment for description and no further details are given.

[0141] The arrangement order of the low-pass filter and the high-pass filter is determined according to the values ​​of the updated digital sequence to obtain the preset filter group. The above embodiments can be referred to for explanation and will not be described in detail.

[0142] Further, the binary digital marking of the filter path includes:

[0143] If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0; the above description may be referred to and will not be repeated herein.

[0144] If the grid-connected voltage signal passes through a high-pass filter, the marking number for binary digital marking of the filter path is 1. The above description can be referred to, and no further details are given.

[0145] Furthermore, the method of updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes:

[0146] If the number of the value 1 before the position of the currently traversed number is an odd number, the value of the currently traversed number is negated; please refer to the above embodiment for description and will not be repeated here.

[0147] If the number of the value 1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged.

[0148] Furthermore, the traversing of each number in the digital sequence in sequence and updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes:

[0149] The value of the currently traversed number in the digital sequence is updated according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed. Please refer to the above embodiment for description and no further details will be given.

[0150] The numerical processing result includes negating the numerical value of the currently traversed number or keeping the numerical value of the currently traversed number unchanged.

[0151] Figure 7 FIG. 1 is a schematic diagram of a structure of a resonance detection device for a new energy power system provided by an embodiment of the present invention. Figure 7 As shown, a resonance detection device for a new energy power system provided by an embodiment of the present invention includes an extraction unit 701, an extension unit 702 and an analysis unit 703, wherein:

[0152] The extraction unit 701 is used to perform wavelet packet transform on the grid-connected voltage signal according to the preset filter group, obtain multiple sub-bands sorted in order of frequency, and extract the sub-band with the largest signal fluctuation amplitude in the multiple sub-bands as the target sub-band where the resonant signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; the extension unit 702 is used to perform waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extend the two side endpoints of the matching waveform in the direction of the endpoints respectively; the analysis unit 703 is used to analyze the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0153] Specifically, the extraction unit 701 in the device is used to perform wavelet packet transform on the grid-connected voltage signal according to a preset filter group, obtain multiple sub-bands sorted in order of frequency, and extract the sub-band with the largest signal fluctuation amplitude in the multiple sub-bands as the target sub-band where the resonant signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and are arranged in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; the extension unit 702 is used to perform waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extend the two side endpoints of the matching waveform in the direction of the endpoints; the analysis unit 703 is used to analyze the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0154] The resonance detection device of the new energy power system provided by the embodiment of the present invention performs wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-bands sorted in order of frequency size, and extracts the sub-band with the largest signal fluctuation amplitude in the multiple sub-bands as the target sub-band where the resonance signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in sequence in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; waveform matching is performed on the characteristic waveform in the target sub-band to obtain a matching waveform, and the endpoints on both sides of the matching waveform are respectively extended in the direction of the endpoints; the extended signal is analyzed to obtain the resonance frequency and amplitude of the new energy power generation grid-connected system, which can effectively determine the resonance frequency and improve the detection speed and accuracy.

[0155] Furthermore, the extension unit 702 is specifically used for:

[0156] The matching waveform is obtained by matching the amplitude, rise time and fall time of the characteristic waveform.

[0157] Furthermore, the resonance detection device of the new energy power system is also used for:

[0158] Obtaining the filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence, and marking the filter path with binary digital marks;

[0159] Arrange the marked binary digits in sequence to obtain a digital sequence;

[0160] Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence;

[0161] The arrangement order of the low-pass filter and the high-pass filter is determined according to the values ​​of the updated digital sequence to obtain the preset filter group.

[0162] Furthermore, the resonance detection device of the new energy power system is also specifically used for:

[0163] If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0;

[0164] If the grid-connected voltage signal passes through a high-pass filter, the marking number for binary digital marking of the filter path is 1.

[0165] Furthermore, the resonance detection device of the new energy power system is also specifically used for:

[0166] If the number of 1s before the position of the currently traversed number is an odd number, negate the value of the currently traversed number;

[0167] If the number of values ​​1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged.

[0168] Furthermore, the resonance detection device of the new energy power system is also specifically used for:

[0169] updating the value of the currently traversed number in the digital sequence according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed;

[0170] The numerical processing result includes negating the numerical value of the currently traversed number, or keeping the numerical value of the currently traversed number unchanged.

[0171] An embodiment of the present invention provides an embodiment of a resonance detection device for a new energy power system, which can be specifically used to execute the processing flow of the above-mentioned method embodiments. Its functions are not repeated here, and reference can be made to the detailed description of the above-mentioned method embodiments.

[0172] Figure 8 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention is shown in FIG. Figure 8 As shown, the computer device includes: a memory 801, a processor 802, and a computer program stored in the memory 801 and executable on the processor 802. When the processor 802 executes the computer program, the following method is implemented:

[0173] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0174] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0175] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0176] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0177] This embodiment discloses a computer program product, the computer program product including a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0178] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0179] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0180] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0181] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0182] This embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0183] Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located;

[0184] The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter;

[0185] Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located;

[0186] The extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system.

[0187] Compared with the technical solutions in the prior art, the embodiments of the present invention perform wavelet packet transformation on the grid-connected voltage signal according to a preset filter group to obtain multiple sub-bands sorted in order of frequency, and extract the sub-band with the largest signal fluctuation amplitude from the multiple sub-bands as the target sub-band where the resonant signal is located; wherein the preset filter group includes filter groups connected in sequence, each filter group includes four filters, and is arranged in sequence in the order of low-pass filter, high-pass filter, high-pass filter and low-pass filter; waveform matching is performed on the characteristic waveform in the target sub-band to obtain a matching waveform, and the endpoints on both sides of the matching waveform are respectively extended in the direction of the endpoints; the extended signal is analyzed to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system, which can effectively determine the resonant frequency and improve the detection speed and accuracy.

[0188] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0189] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0190] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0191] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0192] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0193] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A resonance detection method for a new energy power system, characterized in that: include: Performing wavelet packet transformation on the grid-connected voltage signal according to the preset filter group to obtain multiple sub-frequency bands sorted in order of frequency magnitude, and extracting the sub-frequency band with the largest signal fluctuation amplitude from the multiple sub-frequency bands as the target sub-frequency band where the resonant signal is located; The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter; Performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and extending the endpoints on both sides of the matching waveform in the directions where the endpoints are located; The extended signal is analyzed to obtain the resonant frequency and amplitude of the renewable energy power generation grid-connected system; Acquiring the preset filter group includes: Obtaining the filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence, and marking the filter path with binary digital marks; Arrange the marked binary digits in sequence to obtain a digital sequence; Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence; Determine the arrangement order of the low-pass filter and the high-pass filter according to the values ​​of the updated digital sequence to obtain the preset filter group; The step of marking the filter path with binary digital information comprises: If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0; If the grid-connected voltage signal passes through a high-pass filter, the marking digit for binary digital marking of the filter path is 1; The method updates the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position, and obtains an updated digital sequence, including: If the number of 1s before the position of the currently traversed number is an odd number, negate the value of the currently traversed number; If the number of values ​​1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged; The method of sequentially traversing each number in the digital sequence and updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes: updating the value of the currently traversed number in the digital sequence according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed; The numerical processing result includes negating the numerical value of the currently traversed number, or keeping the numerical value of the currently traversed number unchanged.

2. The resonance detection method of the new energy power system according to claim 1 is characterized in that: The step of performing waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform includes: The matching waveform is obtained by matching the amplitude, rise time and fall time of the characteristic waveform.

3. A resonance detection device for a new energy power system, characterized in that: include: An extraction unit is used to perform wavelet packet transformation on the grid-connected voltage signal according to a preset filter group to obtain a plurality of sub-frequency bands sorted in order of frequency magnitude, and extract a sub-frequency band with the largest signal fluctuation amplitude from the plurality of sub-frequency bands as a target sub-frequency band where the resonance signal is located; The preset filter group includes filter subgroups connected in sequence, each filter subgroup includes four filters, and the filters are arranged in the order of a low-pass filter, a high-pass filter, a high-pass filter and a low-pass filter; An extension unit, configured to perform waveform matching on the characteristic waveform in the target sub-band to obtain a matching waveform, and to extend the endpoints on both sides of the matching waveform in the directions of the endpoints; An analysis unit is used to analyze the extended signal to obtain the resonant frequency and amplitude of the new energy power generation grid-connected system; Acquiring the preset filter group includes: Obtaining the filter path of the grid-connected voltage signal when it passes through the low-pass filter and the high-pass filter in sequence, and marking the filter path with binary digital marks; Arrange the marked binary digits in sequence to obtain a digital sequence; Traverse each number in the digital sequence in turn, and update the value of the current traversal number according to the value of the current traversal number and the number of values ​​1 before the position, to obtain an updated digital sequence; Determine the arrangement order of the low-pass filter and the high-pass filter according to the values ​​of the updated digital sequence to obtain the preset filter group; The step of marking the filter path with binary digital information comprises: If the grid-connected voltage signal passes through a low-pass filter, the marking number for binary digital marking of the filter path is 0; If the grid-connected voltage signal passes through a high-pass filter, the marking digit for binary digital marking of the filter path is 1; The method updates the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position, and obtains an updated digital sequence, including: If the number of 1s before the position of the currently traversed number is an odd number, negate the value of the currently traversed number; If the number of values ​​1 before the position of the currently traversed number is an even number, the value of the currently traversed number is saved unchanged; The method of sequentially traversing each number in the digital sequence and updating the value of the currently traversed number according to the value of the currently traversed number and the number of values ​​1 before the position thereof to obtain an updated digital sequence includes: updating the value of the currently traversed number in the digital sequence according to the numerical processing result of the currently traversed number until all the numbers in the digital sequence are traversed; The numerical processing result includes negating the numerical value of the currently traversed number, or keeping the numerical value of the currently traversed number unchanged.

4. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to claim 1 or 2 is implemented.

5. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to claim 1 or 2 is implemented.

6. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to claim 1 or 2 is implemented.

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