Lightning arrester resistive current detection method, device, system, medium, and chip

Abstract

The present invention discloses a detection method, device, system, medium and chip for resistive current of a lightning arrester, and relates to the field of electrical measurement technology. The detection method comprises: collecting the current of the lightning arrester through a current transformer to obtain a full current signal; performing Fourier transformation on the full current signal to obtain a fundamental current and a third harmonic current; obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; determining the phase of the interphase interference current of the lightning arrester, and obtaining the phase of the capacitive current of the lightning arrester according to the phase of the fundamental voltage; obtaining the effective value of the interphase interference current and the effective value of the capacitive current, and obtaining the resistive current waveform signal of the lightning arrester according to the full current signal, the phase and effective value of the interphase interference current, and the phase and effective value of the capacitive current. The method only needs to collect the current signal, which can reduce the on-site construction and installation cost, and can remove the influence of the interphase interference, thereby improving the accuracy of resistive current detection.

Description

Technical Field

[0001] The present invention relates to the field of electrical measurement technology, and in particular to a method, device, system, medium and chip for detecting resistive current of a lightning arrester. Background Art

[0002] As an important part of the protection device for power equipment in high-voltage power grids, the monitoring of the arrester's own performance is also one of the key factors to ensure the normal operation of power equipment. At present, the performance monitoring of lightning arresters mainly relies on measuring the resistive component in its leakage current (or total current). Under normal circumstances, the resistive component current accounts for about 5-20% of the total current, and its order of magnitude is microampere. Therefore, it is difficult to directly measure the resistive current. To this end, the following methods are proposed in the relevant technology:

[0003] 1) Capacitive current compensation method, its basic principle is to use the phase shift of the system voltage signal to compensate the capacitive current component in the full current, so as to obtain the resistive current component. However, when the grid voltage contains harmonics, the capacitive current compensation method does not compensate for the capacitive harmonic current, which greatly interferes with the measurement results and cannot eliminate the influence of the phase-to-phase coupling capacitance.

[0004] 2) Fundamental wave method, which is to obtain the fundamental wave component of resistive current by projecting the fundamental wave component of full current on the fundamental wave component of voltage, so as to achieve the purpose of monitoring the resistive current of lightning arrester. However, this method does not consider the change of higher harmonic components of resistive current, nor can it eliminate the influence of phase-to-phase coupling capacitance.

[0005] 3) Zero-sequence current method, the principle is to monitor the sum of the total leakage current flowing through the A, B, C three-phase arrester, that is, the sum of the resistive third harmonic current flowing through the arrester, and to achieve the purpose of monitoring the arrester resistive current according to the change of the grounding current amplitude of the three-phase arrester. However, this method is greatly affected by the third harmonic of the grid voltage, and it is also unable to eliminate the influence of the phase-to-phase coupling capacitance.

[0006] 4) Harmonic analysis method, which is to perform FFT (Fast Fourier Transforming) on ​​the bus voltage and the full current flowing through the arrester to obtain the amplitude and phase angle of each harmonic, and then use the orthogonality of trigonometric functions to separate the resistive current fundamental wave and each harmonic component value from the total leakage current. However, this method has a large amount of calculation and cannot eliminate the influence of phase-to-phase coupling capacitance. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the purpose of the present invention is to provide a method, device, system, medium and chip for detecting resistive current of a lightning arrester, so as to reduce the cost of on-site construction and installation and improve the accuracy of resistive current detection.

[0008] In the first aspect, an embodiment of the present invention proposes a method for detecting the resistive current of a lightning arrester, comprising: collecting the current of the lightning arrester through a current transformer to obtain a full current signal; performing Fourier transform on the full current signal to obtain a fundamental current and a third harmonic current; obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; determining the phase of the phase-to-phase interference current of the lightning arrester, and obtaining the phase of the capacitive current of the lightning arrester according to the phase of the fundamental voltage; obtaining the effective value of the phase-to-phase interference current and the effective value of the capacitive current, and obtaining the resistive current waveform signal of the lightning arrester according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current.

[0009] According to one embodiment of the present invention, the full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; before performing Fourier transform on the full current signal, the method further includes: calculating the angle between the current values ​​collected in the current two adjacent cycles; obtaining the actual current frequency according to the angle and the current collection frequency, and obtaining the actual number of collection points in each cycle according to the actual current frequency and the current collection frequency; if the actual number of collection points is equal to the target number of collection points, locking the actual current frequency; if the actual number of collection points is not equal to the target number of collection points, calculating the angle between the current values ​​collected in the next two adjacent cycles, and going to the step of obtaining the actual current frequency according to the angle and the current collection frequency; performing Fourier transform on the full current signal includes: performing Fourier transform on the full current signal based on the target number of collection points and the locked actual current frequency.

[0010] According to an embodiment of the present invention, the method further includes: if the number of determinations that the actual number of acquisition points is not equal to the target number of acquisition points reaches a preset number threshold, issuing a prompt message to provide a loss of lock prompt and ending the current detection process.

[0011] According to one embodiment of the present invention, obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current includes: obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current based on the positional relationship between the zero crossing points of the fundamental current and the third harmonic current.

[0012] According to an embodiment of the present invention, determining the phase of the arrester interphase interference current includes: obtaining the phase of the three-phase interphase interference current of the arrester according to the vector relationship of the full current components of the arrester.

[0013] According to an embodiment of the present invention, the phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

[0014] According to one embodiment of the present invention, the resistive current waveform signal of the lightning arrester is obtained according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current, including: obtaining the phase-to-phase interference current waveform signal according to the phase and effective value of the phase-to-phase interference current, obtaining the capacitive current waveform signal according to the phase and effective value of the capacitive current, and obtaining the full current waveform signal according to the full current signal; based on the vector relationship between the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal, and the phase-to-phase interference current waveform signal, the resistive current waveform signal is obtained according to the full current waveform signal, the capacitive current waveform signal, and the phase-to-phase interference current waveform signal.

[0015] In the second aspect, an embodiment of the present invention proposes a detection device for the resistive current of a lightning arrester, comprising: an acquisition module, which is used to collect the current of the lightning arrester through a current transformer to obtain a full current signal; a transformation module, which is used to perform Fourier transform on the full current signal to obtain a fundamental current and a third harmonic current; a first calculation module, which is used to obtain the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; a determination module, which is used to determine the phase of the interphase interference current of the lightning arrester; a second calculation module, which is used to obtain the phase of the capacitive current of the lightning arrester according to the phase of the fundamental voltage; an acquisition module, which is used to obtain the effective value of the interphase interference current and the effective value of the capacitive current; a third calculation module, which is used to obtain the resistive current waveform signal of the lightning arrester according to the full current signal, the phase and effective value of the interphase interference current, and the phase and effective value of the capacitive current.

[0016] According to one embodiment of the present invention, the full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; the device also includes a locking module, which is used to: before performing Fourier transform on the full current signal, calculate the angle between the current values ​​collected in the current two adjacent cycles; obtain the actual current frequency according to the angle and the current collection frequency, and obtain the actual number of collection points in each cycle according to the actual current frequency and the current collection frequency; if the actual number of collection points is equal to the target number of collection points, lock the actual current frequency; if the actual number of collection points is not equal to the target number of collection points, calculate the angle between the current values ​​collected in the next two adjacent cycles, and go to the step of obtaining the actual current frequency according to the angle and the current collection frequency; when performing Fourier transform on the full current signal, the transformation module is used to perform Fourier transform on the full current signal based on the target number of collection points and the locked actual current frequency.

[0017] According to an embodiment of the present invention, the locking module is further used to: when the number of judgments that the actual number of collection points is not equal to the target number of collection points reaches a preset number threshold, issue a prompt message to provide a loss of lock prompt and end the current detection process.

[0018] According to one embodiment of the present invention, the first calculation module is specifically used to obtain the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current based on the positional relationship between the zero-crossing points of the fundamental current and the third harmonic current.

[0019] According to an embodiment of the present invention, the determination module is specifically used to obtain the phase of the three-phase interphase interference current of the arrester according to the vector relationship of the full current components of the arrester.

[0020] According to an embodiment of the present invention, the phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

[0021] According to one embodiment of the present invention, the third calculation module is specifically used to: obtain an inter-phase interference current waveform signal according to the phase and effective value of the inter-phase interference current, obtain a capacitive current waveform signal according to the phase and effective value of the capacitive current, and obtain a full current waveform signal according to the full current signal; based on the vector relationship between the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal, obtain the resistive current waveform signal according to the full current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal.

[0022] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for detecting resistive current of a lightning arrester described in the first aspect above is implemented.

[0023] In a fourth aspect, an embodiment of the present invention proposes a chip, comprising a memory, a processor, and a computer program stored in the memory, wherein when the computer program is executed by the processor, the method for detecting resistive current of the lightning arrester described in the first aspect is implemented.

[0024] In a fifth aspect, an embodiment of the present invention proposes a system for detecting resistive current of a lightning arrester, comprising: a current transformer for collecting the current of the lightning arrester to obtain a full current signal; and the chip described in the fourth aspect above, connected to the current transformer.

[0025] The detection method, device, system, medium and chip of the resistive current of the arrester of the embodiment of the present invention first collects the current of the arrester through a current transformer to obtain a full current signal; then Fourier transforms the full current signal to obtain a fundamental current and a third harmonic current, and obtains the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; then determines the phase of the arrester interphase interference current, and obtains the phase of the arrester capacitive current according to the phase of the fundamental voltage; finally obtains the effective value of the interphase interference current and the effective value of the capacitive current, and obtains the resistive current waveform signal of the arrester according to the full current signal, the phase and effective value of the interphase interference current, and the phase and effective value of the capacitive current. The whole process only needs to collect the current signal, which can reduce the on-site construction and installation cost, and can remove the influence of the interphase interference, thereby improving the accuracy of resistive current detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of a method for detecting resistive current of a lightning arrester according to an embodiment of the present invention;

[0027] Figure 2 is an equivalent circuit diagram of a single lightning arrester of an example of the present invention;

[0028] Figure 3 is an equivalent circuit diagram of a three-phase lightning arrester according to an example of the present invention;

[0029] FIG4 (a) is a vector relationship diagram of the A-phase current component according to an example of the present invention;

[0030] FIG4( b ) is a vector relationship diagram of the B-phase current component according to an example of the present invention;

[0031] FIG4( c ) is a vector relationship diagram of a C-phase current component according to an example of the present invention;

[0032] Figure 5 is a flow chart of obtaining the actual current frequency according to an example of the present invention;

[0033] FIG6 (a) is a structural block diagram of a device for detecting resistive current of a lightning arrester according to an embodiment of the present invention;

[0034] FIG6 (b) is a structural block diagram of a lightning arrester resistive current detection device according to another embodiment of the present invention;

[0035] Figure 7 is a structural block diagram of a chip according to an embodiment of the present invention;

[0036] Figure 8 It is a structural block diagram of a lightning arrester resistive current detection system according to an embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 600, a detection device for resistive current of a lightning arrester, 610, a collection module, 620, a transformation module, 630, a first calculation module, 640, a determination module, 650, a second calculation module, 660, an acquisition module, 670, a third calculation module, 680, a locking module;

[0039] 700, chip, 701, processor, 702, bus, 703, memory, 704, transceiver;

[0040] 800. Lightning arrester resistive current detection system. 810. Current transformer. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] In order to detect the resistive current of the arrester, the related technologies have proposed capacitive current compensation method, fundamental wave method, zero-sequence current method, harmonic analysis method and other technologies. However, most of these technologies need to measure the voltage on the end side of the arrester or the secondary voltage, and have the disadvantage of being unable to eliminate the influence of phase-to-phase interference, which increases the on-site construction and installation, and the resistive current detected is also inaccurate. To this end, the present invention proposes a method for detecting the resistive current of the arrester to reduce on-site construction and installation and improve the detection accuracy of the resistive current of the arrester. At the same time, based on the detection method of the resistive current of the arrester, a detection device, system, medium and chip for the resistive current of the arrester are proposed.

[0043] The following describes the arrester resistive current detection method, device, system, medium, and chip according to the embodiments of the present invention with reference to the accompanying drawings.

[0044] Figure 1 The present invention is a flowchart of a method for detecting resistive current of a lightning arrester according to an embodiment of the present invention. The detection method can be executed by a chip, and the chip can include a memory and a processor. A computer program is stored in the memory, and the memory can execute the computer program to implement the method for detecting resistive current of a lightning arrester.

[0045] like Figure 1 As shown, the method for detecting the resistive current of the arrester includes:

[0046] S11, collect the current of the lightning arrester through the current transformer to obtain the full current signal.

[0047] In this embodiment, the arrester is a three-phase arrester, which may include a MOA (metal oxide arrester) valve plate. The three-phase arrester is connected to the three-phase lines A, B, and C respectively, and there is interphase interference between two adjacent phases. For each phase arrester, under the power frequency voltage U (referring to the unified standard voltage of the power industry and electrical equipment, such as 220V and 380V AC voltage), the MOA valve plate can be equivalent to a parallel structure of a nonlinear resistor R and a linear capacitor C, and its equivalent circuit is as follows: Figure 2 shown.

[0048] See also Figure 2 , the current passing through the arrester can be divided into total current, resistive current, and capacitive current, and there is interphase interference between the two adjacent phases of the three-phase arrester. According to the relationship between the total current, resistive current, capacitive current, and interphase interference current, it can be known that ,in, is the total current of the arrester, is the capacitive current, is the resistive current, is the phase-to-phase interference current.

[0049] To detect the resistive current of the arrester, the present invention only needs to collect the current signal instead of the voltage signal, thereby reducing on-site construction and installation. Specifically, a current transformer can be set corresponding to each phase arrester to collect the current of the arrester and obtain a full current signal.

[0050] Among them, the current transformer is an instrument that converts the large current on the primary side into a small current on the secondary side for measurement based on the principle of electromagnetic induction. The current transformer is composed of a closed iron core and a winding. The primary winding has a small number of turns and is connected in series in the circuit where the current needs to be measured; the secondary winding has a large number of turns and is connected to the chip, so that the chip can obtain the full current signal collected by the current transformer based on the small current on the secondary side and the large current on the primary side.

[0051] S12, performing Fourier transform on the full current signal to obtain the fundamental current and the third harmonic current.

[0052] As an implementation method, the full current signal is a continuous signal, and a continuous Fourier transform is performed on the full current signal to obtain the fundamental current (including the amplitude of the fundamental current , Phase ) and third harmonic current (including the amplitude of the third harmonic , Phase ).

[0053] As another embodiment, the full current signal is a discrete signal, for example, the sampling frequency The current frequency is 6.4KHz, the power frequency voltage frequency is 50Hz, and N=128 points are collected in each cycle. In this embodiment, the full current signal is subjected to a discrete Fourier transform to obtain the fundamental current (including the amplitude of the fundamental current , Phase ) and third harmonic current (including the amplitude of the third harmonic , Phase ).

[0054] S13, obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current.

[0055] In this embodiment, the phase of the fundamental voltage can be obtained according to the phase of the fundamental current and the phase of the third harmonic current based on the positional relationship between the zero-crossing points of the fundamental current and the third harmonic current.

[0056] Specifically, according to the positional relationship between the zero crossing points of the third harmonic and the fundamental wave, in one cycle, the third harmonic crosses the zero point 6 times, the third harmonic and the fundamental wave zero crossing overlap 2 times, and the phase angle of the three zero crossings must coincide with the phase of the fundamental wave voltage. Taking the zero crossing position of the third harmonic as a reference and taking phase A as an example, the phase angle of the zero crossing is , randomly select three points in a cycle, here we select the first three points, that is, k=0, 1, 2, and the phase angles of the corresponding three points are , , .

[0057] The phase angle of the full current leading the fundamental voltage is close to 90°, that is, the phase angle of the third harmonic zero crossing point corresponds to the full current phase amplitude of the full current peak value, so it is determined , , One of the phases is used as the phase of the fundamental voltage of phase A Similarly, the phases of the fundamental voltages of phases B and C are obtained and recorded as and .

[0058] S14, determining the phase of the arrester interphase interference current, and obtaining the phase of the arrester capacitive current according to the phase of the fundamental voltage.

[0059] Specifically, the phase of the three-phase interphase interference current of the arrester can be obtained according to the vector relationship of the total current components of the arrester.

[0060] In some examples, the three-phase arresters are arranged in a line, such as Figure 3 As shown in the figure, the distance between phase A and phase B, and the distance between phase B and phase C are basically the same. Usually, only the interference between two adjacent phases is considered. Figure 3 middle , , Respectively represent the voltage of phase A, phase B, and phase C, , , , They represent the equivalent capacitance of the A-phase, B-phase, and C-phase arresters and the equivalent capacitance of the interphase interference. Indicates the equivalent resistance of the A-phase, B-phase, and C-phase arresters.

[0061] For phase A: resistive current I res and bus voltage U a Phase consistent, capacitive current I cap The phase leads the bus voltage U a The phase is 90 degrees, and the interference equivalent capacitance of phase B to phase A is The phase leads the B-phase bus voltage U b The phase is 90 degrees, as shown in Figure 4 (a).

[0062] For phase B: resistive current I res and bus voltage U b Phase consistent, capacitive current I cap The phase leads the bus voltage U b The phase is 90 degrees, the interference equivalent capacitance of phase A to phase B The phase leads the A-phase bus voltage U a The phase is 90 degrees, and the interference equivalent capacitance of phase C to phase B is The phase leads the C-phase bus voltage Uc The phase is 90 degrees, as shown in Figure 4 (b).

[0063] For phase C: resistive current I res and bus voltage U c Phase consistent, capacitive current I cap The phase leads the bus voltage U c The phase is 90 degrees, and the interference equivalent capacitance of phase B to phase C Phase, leading B-phase bus voltage U b The phase is 90 degrees, as shown in Figure 4 (c).

[0064] As shown in Figure 4 (a)-Figure 4 (b), the phase difference between the bus voltages of phases A, B, and C is 120 degrees. In phase A, the phase of the interference equivalent capacitance of phase B leads the phase of the bus voltage of phase B by 90 degrees, that is, the phase of the phase-to-phase interference equivalent capacitance lags the phase of the bus voltage of phase A by 30 degrees. In phase B, the phase of the interference equivalent capacitance of phase A leads the phase of the bus voltage of phase A by 90 degrees, and the phase of the interference equivalent capacitance of phase C leads the phase of the bus voltage of phase C by 90 degrees. The total phase-to-phase interference equivalent capacitance is the sum of the interference equivalent capacitance of phase A and the interference equivalent capacitance of phase C, that is, the phase of the total phase-to-phase interference equivalent capacitance lags the phase of the bus voltage of phase B by 90 degrees. In phase C, the phase of the interference equivalent capacitance of phase B leads the phase of the bus voltage of phase B by 90 degrees, that is, the phase of the phase-to-phase interference equivalent capacitance lags the phase of the bus voltage of phase C by 120 degrees. Among them, the phase of each phase bus voltage can be expressed by the phase of the fundamental voltage of the corresponding phase, thereby obtaining the phase of the interphase interference current of the three phases A, B, and C: , , .

[0065] In some embodiments of the present invention, the phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

[0066] Specifically, according to Figure 2 From the equivalent circuit of the arrester shown, it can be seen that the current flowing through the linear capacitor (i.e. the capacitive current of the arrester) has no harmonics and its phase leads the bus voltage by 90 degrees. The phase of each phase bus voltage can be represented by the phase of the fundamental voltage of the corresponding phase. The phases of the capacitive currents of phases A, B, and C are respectively 、 、 ,have 、 、 。

[0067] S15, obtaining the effective value of the phase-to-phase interference current and the effective value of the capacitive current, and obtaining the resistive current waveform signal of the arrester according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current.

[0068] In some embodiments of the present invention, the effective value of the phase-to-phase interference current and the effective value of the capacitive current can be determined by calculation (the specific calculation method will be described later). After that, the phase-to-phase interference current waveform signal can be obtained according to the phase and effective value of the phase-to-phase interference current, the capacitive current waveform signal can be obtained according to the phase and effective value of the capacitive current, and the full current waveform signal can be obtained according to the full current signal, wherein the waveform signal can be represented by a function including amplitude and phase, and the relationship between the effective value and the amplitude is: effective value = amplitude / Based on the vector relationship among the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal and the phase-to-phase interference current waveform signal, the resistive current waveform signal is obtained according to the full current waveform signal, the capacitive current waveform signal and the phase-to-phase interference current waveform signal.

[0069] Specifically, the effective values ​​of the three compatibility currents A, B, and C are respectively , , , combined with the phase of the three-phase compatibility current A, B, and C obtained above 、 、 ， The capacitive current waveform signals of phases A, B, and C can be obtained: , , Similarly, the interphase interference current waveform signals of phases A, B, and C can be obtained: , , If the above-mentioned full current signal is a continuous signal, the full current signal of the three phases A, B, and C can be directly used as the corresponding full current waveform signal , , If the above-mentioned full current signal is a discrete signal, the full current waveform signal can be obtained according to the amplitude and phase of the fundamental current obtained by discrete Fourier transform, as well as the amplitude and phase of the third harmonic. , , .

[0070] The calculation process of the effective value of the phase-to-phase interference current is as follows:

[0071] according to Figure 3 As shown, the symmetrical component method is used to analyze the current:

[0072]

[0073]

[0074]

[0075] In the formula, is the zero sequence current, is the interference current of phase B to phase A, is the interference current of phase B to phase C, Equivalent to the interference current of phase A to phase B, Equivalent to the interference current of phase C to phase B, It is the three-phase current after removing the interphase interference current.

[0076] According to the zero-sequence current, According to Figures 4 to 6, , so it can be deduced that , that is, the zero-sequence current is equal to the phase-to-phase interference current, so the zero-sequence current indirectly reflects the intensity of the phase-to-phase interference.

[0077] The effective value of the phase-to-phase interference current of phase B is equal to the effective value of the zero-sequence current. According to the basic theory of power system, the effective value of the phase-to-phase interference current of phase B can be obtained as Similarly, the effective value of the phase-to-phase interference current of phase A can be obtained: and the effective value of the phase-to-phase interference current of phase C .

[0078] The calculation process of the effective value of the capacitive current is as follows:

[0079] According to Figures 4 to 6, using the vector relationship of the current components, the waveform of the current after removing the interphase interference is obtained:

[0080]

[0081]

[0082]

[0083] The waveform of the unit capacitive current is calculated by the following formula:

[0084]

[0085]

[0086]

[0087] Where N is the number of sampling points in each sampling period.

[0088] The effective value of the capacitive current is calculated by the following formula:

[0089]

[0090]

[0091]

[0092] Afterwards, according to the vector relationship between the total current, resistive current, capacitive current, and phase interference shown in Figures 4 to 6, the resistive current waveform signals of the three phases A, B, and C are obtained. , and :

[0093]

[0094]

[0095]

[0096] After the resistive current waveform signal is detected, the peak value, resistance-capacitance ratio, etc. of the resistive current can be calculated based on the resistive current waveform to serve as characteristic data for quantitative judgment of the arrester performance.

[0097] In some embodiments of the present invention, the full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; Figure 5 As shown, before Fourier transforming the full current signal, the method further includes:

[0098] S51, calculate the angle between the current values ​​collected in two adjacent cycles.

[0099] S52, obtaining the actual current frequency according to the angle and the current collection frequency, and obtaining the actual number of collection points in each cycle according to the actual current frequency and the current collection frequency.

[0100] S53: If the actual number of acquisition points is equal to the target number of acquisition points, the actual current frequency is locked.

[0101] S54, if the actual number of acquisition points is not equal to the target number of acquisition points, then calculate the angle between the current values ​​acquired in the next two adjacent cycles, and go to the step of obtaining the actual current frequency according to the angle and the current acquisition frequency.

[0102] In this embodiment, performing Fourier transform on the full current signal includes: performing Fourier transform on the full current signal based on the target acquisition point number and the locked actual current frequency.

[0103] Specifically, if the full current signal is a continuous signal, the full current signal may be sampled, for example, with a sampling frequency of is 6.4KHz, the current frequency is 50Hz, and N=128 points can be collected in each cycle. If the full current signal is a discrete signal, then when the sampling frequency When the current frequency is 6.4KHz and 50Hz, N=128 points can be directly collected in each cycle. Based on this, the locking (i.e. locking the actual current frequency) process can be as follows:

[0104] 1) The total current values ​​of two adjacent cycles are and ;

[0105] 2) According to and Calculate the angle between two adjacent cycle current values .

[0106] 3) Update the actual current frequency according to the following formula :

[0107]

[0108] 4) According to the actual current frequency Recalculate points ;

[0109] 5) Points Compare with the number of points N, if they are consistent, lock the actual current frequency , otherwise, return 1 according to the number of points N), and calculate based on the full current value of the next two adjacent cycles.

[0110] Based on the above locking process, an accurate current frequency can be obtained. Then, the full current signal is Fourier transformed based on the target acquisition points and the locked actual current frequency, which can improve the accuracy of the transformation and obtain more accurate fundamental current and third harmonic current.

[0111] The above sampling can be AD (analog-to-digital conversion) sampling. After AD sampling, the current value is directly enlarged by 100,000 times, and the frequency update calculation can adopt the Q20 format (data resolution: 1 / 2^20), that is, the original frequency value is enlarged by 2^20 times, and the decimal part is eliminated. Similarly, according to actual conditions, the Fourier transform can adopt the Q22 format, and the angle value calculation can adopt the Q28 format. Therefore, the present invention expands the current value by 100,000 times to eliminate the decimal place; at the same time, the calculation of 2 to the power of n and the restoration are realized through shift operations, thereby avoiding the use of floating point calculations and greatly improving the calculation speed.

[0112] In some examples, in order to prevent the above locking process from falling into an infinite loop, it can be set that: if the number of judgments that the actual number of collection points is not equal to the target number of collection points reaches a preset threshold (which can be set as needed, such as 3 times, 4 times, 5 times, etc.), a prompt message is issued to prompt a loss of lock and the current detection process is terminated.

[0113] The method for detecting the resistive current of the lightning arrester in the embodiment of the present invention only needs to collect current signals but not voltage signals, thereby reducing on-site construction and installation costs; the phase-to-phase interference current can be obtained, thereby effectively removing the influence of the phase-to-phase interference and making the calculation of the resistive current more accurate; the actual frequency is calculated by using the full current sampling value within 2 cycles, thereby improving the frequency adaptation range of the method of the present invention. For example, when the default current frequency is 50 Hz, the method of the present invention can be applicable to all current frequencies whose actual current frequencies are between 45 Hz and 55 Hz.

[0114] FIG6( a ) is a structural block diagram of a device for detecting resistive current of a lightning arrester according to an embodiment of the present invention.

[0115] As shown in FIG. 6( a ), the arrester resistive current detection device 600 includes: a collection module 610 , a transformation module 620 , a first calculation module 630 , a determination module 640 , a second calculation module 650 , an acquisition module 660 and a third calculation module 670 .

[0116] Among them, the acquisition module 610 is used to collect the current of the lightning arrester through the current transformer to obtain the full current signal; the transformation module 620 is used to perform Fourier transform on the full current signal to obtain the fundamental current and the third harmonic current; the first calculation module 630 is used to obtain the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; the determination module 640 is used to determine the phase of the phase-to-phase interference current of the lightning arrester; the second calculation module 650 is used to obtain the phase of the capacitive current of the lightning arrester according to the phase of the fundamental voltage; the acquisition module 660 is used to obtain the effective value of the phase-to-phase interference current and the effective value of the capacitive current; the third calculation module 670 is used to obtain the resistive current waveform signal of the lightning arrester according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current.

[0117] In some embodiments of the present invention, the full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; as shown in Figure 6 (b), the device 600 also includes a locking module 680, which is used to: before performing Fourier transform on the full current signal, calculate the angle between the current values ​​collected in the current two adjacent cycles; obtain the actual current frequency according to the angle and the current collection frequency, and obtain the actual number of collection points in each cycle according to the actual current frequency and the current collection frequency; if the actual number of collection points is equal to the target number of collection points, lock the actual current frequency; if the actual number of collection points is not equal to the target number of collection points, calculate the angle between the current values ​​collected in the next two adjacent cycles, and go to the step of obtaining the actual current frequency according to the angle and the current collection frequency.

[0118] In this embodiment, when performing Fourier transform on the full current signal, the transform module 620 is used to perform Fourier transform on the full current signal based on the target acquisition points and the locked actual current frequency.

[0119] In some embodiments of the present invention, the locking module 680 is further used to: when the number of judgments that the actual number of acquisition points is not equal to the target number of acquisition points reaches a preset number threshold, issue a prompt message to provide a loss of lock prompt and end the current detection process.

[0120] In some embodiments of the present invention, the first calculation module 630 is specifically used to obtain the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current based on the positional relationship between the zero-crossing points of the fundamental current and the third harmonic current.

[0121] In some embodiments of the present invention, the determination module 640 is specifically used to obtain the phase of the three-phase interphase interference current of the arrester according to the vector relationship of the total current components of the arrester.

[0122] In some embodiments of the present invention, the phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

[0123] In some embodiments of the present invention, the third calculation module 670 is specifically used to: obtain an interphase interference current waveform signal according to the phase and effective value of the interphase interference current, obtain a capacitive current waveform signal according to the phase and effective value of the capacitive current, and obtain a full current waveform signal according to the full current signal; based on the vector relationship between the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal, and the interphase interference current waveform signal, obtain a resistive current waveform signal according to the full current waveform signal, the capacitive current waveform signal, and the interphase interference current waveform signal.

[0124] It should be noted that, for other specific implementations of the arrester resistive current detection device 600 according to the embodiment of the present invention, reference may be made to the specific implementations of the arrester resistive current detection method according to the above embodiment of the present invention.

[0125] Based on the method for detecting resistive current of a lightning arrester in the above-mentioned embodiment, the present invention proposes a computer-readable storage medium.

[0126] In this embodiment, a computer program is stored on a computer-readable storage medium. When the computer program is executed by a processor, the above-mentioned method for detecting resistive current of a lightning arrester is implemented.

[0127] Figure 7 It is a structural block diagram of a chip according to an embodiment of the present invention.

[0128] like Figure 7 As shown, the chip 700 includes: a processor 701 and a memory 703. The processor 701 and the memory 703 are connected, such as through a bus 702. Optionally, the chip 700 may also include a transceiver 704. It should be noted that in actual applications, the transceiver 704 is not limited to one, and the structure of the chip 700 does not constitute a limitation on the embodiments of the present invention.

[0129] The processor 701 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It may implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of the present invention. The processor 701 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0130] The bus 702 may include a path to transmit information between the above components. The bus 702 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus. The bus 702 may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 7Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0131] The memory 703 is used to store a computer program corresponding to the method for detecting the resistive current of the arrester of the above embodiment of the present invention, and the computer program is controlled and executed by the processor 701. The processor 701 is used to execute the computer program stored in the memory 703 to implement the contents shown in the above method embodiment.

[0132] Among them, the chip 700 can be set in mobile terminals including but not limited to: mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), etc., as well as fixed terminals such as digital TVs, desktop computers, etc. Figure 7 The chip 700 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0133] Figure 8 It is a structural block diagram of a lightning arrester resistive current detection system according to an embodiment of the present invention.

[0134] like Figure 8 As shown, the arrester resistive current detection system 800 includes: a current transformer 810 and the chip 700 of the above embodiment.

[0135] The current transformer 810 is used to collect the current of the arrester to obtain a full current signal. The chip 700 is connected to the current transformer 810 .

[0136] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0137] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", 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.

[0139] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0140] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0141] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0142] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0143] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for detecting resistive current of a lightning arrester, characterized in that: include: The current of the arrester is collected through a current transformer to obtain a full current signal; Performing Fourier transformation on the full current signal to obtain a fundamental current and a third harmonic current; Obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; Determine the phase of the arrester interphase interference current, and obtain the phase of the arrester capacitive current according to the phase of the fundamental voltage; Obtaining the effective value of the phase-to-phase interference current and the effective value of the capacitive current, and obtaining the resistive current waveform signal of the arrester according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current; The full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; before performing Fourier transform on the full current signal, the method further includes: Calculate the angle between the current values ​​collected in two adjacent cycles; Obtaining an actual current frequency according to the angle and the current acquisition frequency, and obtaining an actual number of acquisition points in each cycle according to the actual current frequency and the current acquisition frequency; If the actual number of acquisition points is equal to the target number of acquisition points, locking the actual current frequency; If the actual number of acquisition points is not equal to the target number of acquisition points, the angle between the current values ​​acquired in the next two adjacent cycles is calculated, and the process proceeds to the step of obtaining the actual current frequency according to the angle and the current acquisition frequency; The performing Fourier transform on the full current signal includes: performing Fourier transform on the full current signal based on the target acquisition point number and the locked actual current frequency.

2. The method for detecting the resistive current of a lightning arrester according to claim 1, characterized in that: The method further comprises: If the number of times that the actual number of acquisition points is not equal to the target number of acquisition points reaches a preset number threshold, a prompt message is issued to provide a lock-out prompt and the current detection process ends.

3. The method for detecting resistive current of a lightning arrester according to claim 1, characterized in that: The obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current includes: Based on the positional relationship between the zero-crossing points of the fundamental current and the third harmonic current, the phase of the fundamental voltage is obtained according to the phase of the fundamental current and the phase of the third harmonic current.

4. The method for detecting the resistive current of a lightning arrester according to claim 1, characterized in that: The arrester is a three-phase arrester and is arranged in a line; the phase of the interphase interference current of the arrester is determined, including: According to the vector relationship of the total current components of the arrester, the phase of the three-phase interphase interference current of the arrester is obtained.

5. The method for detecting resistive current of a lightning arrester according to claim 1, characterized in that: The phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

6. The method for detecting the resistive current of a lightning arrester according to claim 1, characterized in that: The method of obtaining the resistive current waveform signal of the arrester according to the full current signal, the phase and the effective value of the phase-to-phase interference current, and the phase and the effective value of the capacitive current comprises: Obtaining an interphase interference current waveform signal according to the phase and effective value of the interphase interference current, obtaining a capacitive current waveform signal according to the phase and effective value of the capacitive current, and obtaining a full current waveform signal according to the full current signal; Based on the vector relationship between the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal, the resistive current waveform signal is obtained according to the full current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal.

7. A lightning arrester resistive current detection device, characterized in that: include: The acquisition module is used to collect the current of the arrester through the current transformer to obtain the full current signal; A transformation module, used for performing Fourier transformation on the full current signal to obtain a fundamental current and a third harmonic current; A first calculation module, used for obtaining the phase of the fundamental voltage according to the phase of the fundamental current and the phase of the third harmonic current; A determination module, used to determine the phase of the interphase interference current of the arrester; A second calculation module, used for obtaining the phase of the capacitive current of the arrester according to the phase of the fundamental voltage; An acquisition module, used for acquiring the effective value of the interphase interference current and the effective value of the capacitive current; A third calculation module, used to obtain a resistive current waveform signal of the arrester according to the full current signal, the phase and effective value of the phase-to-phase interference current, and the phase and effective value of the capacitive current; The full current signal includes current values ​​collected in multiple cycles, and the number of current values ​​collected in each cycle is the target number of collection points; the device also includes a locking module, which is used to: Before performing Fourier transform on the full current signal, calculating the angle between the current values ​​collected in two adjacent cycles; Obtaining an actual current frequency according to the angle and the current acquisition frequency, and obtaining an actual number of acquisition points in each cycle according to the actual current frequency and the current acquisition frequency; If the actual number of acquisition points is equal to the target number of acquisition points, locking the actual current frequency; If the actual number of acquisition points is not equal to the target number of acquisition points, the angle between the current values ​​acquired in the next two adjacent cycles is calculated, and the process proceeds to the step of obtaining the actual current frequency according to the angle and the current acquisition frequency; When performing Fourier transform on the full current signal, the transform module is used to perform Fourier transform on the full current signal based on the target number of acquisition points and the locked actual current frequency.

8. The device for detecting resistive current of a lightning arrester according to claim 7, characterized in that: The locking module is also used for: When the number of determinations that the actual number of acquisition points is not equal to the target number of acquisition points reaches a preset number threshold, a prompt message is issued to provide a lock-out prompt, and the current detection process is terminated.

9. The device for detecting resistive current of a lightning arrester according to claim 7, characterized in that: The first calculation module is specifically used for: Based on the positional relationship between the zero-crossing points of the fundamental current and the third harmonic current, the phase of the fundamental voltage is obtained according to the phase of the fundamental current and the phase of the third harmonic current.

10. The device for detecting resistive current of a lightning arrester according to claim 7, characterized in that: The arrester is a three-phase arrester and is arranged in a line; the determination module is specifically used for: According to the vector relationship of the total current components of the arrester, the phase of the three-phase interphase interference current of the arrester is obtained.

11. The device for detecting resistive current of a lightning arrester according to claim 7, characterized in that: The phase of the capacitive current leads the phase of the fundamental voltage by 90 degrees.

12. The device for detecting resistive current of a lightning arrester according to claim 7, characterized in that: The third calculation module is specifically used for: Obtaining an interphase interference current waveform signal according to the phase and effective value of the interphase interference current, obtaining a capacitive current waveform signal according to the phase and effective value of the capacitive current, and obtaining a full current waveform signal according to the full current signal; Based on the vector relationship between the full current waveform signal, the resistive current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal, the resistive current waveform signal is obtained according to the full current waveform signal, the capacitive current waveform signal, and the inter-phase interference current waveform signal.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for detecting resistive current of a lightning arrester according to any one of claims 1 to 6 is implemented.

14. A chip comprising a memory, a processor and a computer program stored in the memory, characterized in that: When the computer program is executed by a processor, the method for detecting resistive current of a lightning arrester according to any one of claims 1 to 6 is implemented.

15. A lightning arrester resistive current detection system, characterized in that: include: Current transformer, used to collect the current of the arrester and obtain the full current signal ； The chip according to claim 14, connected to the current transformer.

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