A broadband electromagnetic current transformer applicable to an intelligent integrated switch for a 10 kV distribution network and its performance detection method

Abstract

The present invention relates to a broadband electromagnetic current transformer applicable to an intelligent integrated switch for a 10 kV distribution network and a performance detection method thereof, including a primary current transformer and a secondary current transformer; the primary current transformer includes a shielding shell, a lead wire, and a magnetic core disposed inside the shielding shell; the magnetic core includes a skeleton, a metal ring belt, and an enameled wire; an annular groove is formed inside the shielding shell, and a circumferential cutting gap communicating with the annular groove is provided on the inner circumferential wall of the shielding shell; the secondary current transformer includes a first reference layer, a second signal layer, a third signal layer, and a fourth reference layer; it can effectively collect high-frequency transient information generated during a fault process, improve the bandwidth range, measurement accuracy, and sensitivity of the current transformer, and the secondary current transformer adopts a 4-layer PCB design to overcome the dual constraints of high-frequency signal transmission on the winding in a traditional Rogowski coil. The performance detection method of the present invention can simulate and output any actual on-site waveform for sensor performance testing to control the factory performance of the switch.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment, and particularly relates to a broadband electromagnetic current transformer applicable to an intelligent integrated switch of a 10 kV distribution network and a performance detection method thereof. Background Art

[0002] The distribution network is an important hub connecting the power transmission link and power users, and its power supply reliability is directly related to the user experience. Currently, based on the integrated primary and secondary pole-mounted switches, the fault judgment and section positioning of the distribution network line have been realized, and the procurement volume in State Grid and China Southern Power Grid companies has increased year by year (> 4 billion yuan). However, limited by the terminal layout and monitoring range of distribution automation, it is still difficult to achieve "precision positioning" for fault detection, and only the fault interval positioning at the km level can be realized. Especially in rural power grids or mountainous distribution networks, the monitoring range of distribution automation is generally more than 5 km. After the section judgment is successful, there are still a large number of fault inspection tasks, and the traditional fault inspection workload has not been fundamentally reduced.

[0003] Different from the existing distribution network fault section positioning methods, the traveling wave method mainly uses information such as the phase and amplitude of the traveling wave generated by the fault to determine the fault phase, and determines the fault distance of the power supply line by measuring the transmission time of the current or voltage traveling wave signal between the measurement point and the fault point. It has the characteristics of fast response speed, not affected by the control of power electronic equipment, not affected by the line distributed capacitance and the adjustment of transition resistance, and high ranging accuracy, and has extremely high application prospects in the distribution network.

[0004] Currently, the electromagnetic current sensors applied to the measurement and protection of the integrated primary and secondary switches mainly collect power frequency signals, and have low acquisition accuracy and poor frequency response characteristics for high-frequency signals (traveling wave signals), resulting in difficulty in further using the high-frequency signal components during faults for in-depth fault analysis. At the same time, the current transformers used for the integrated primary and secondary intelligent switches lack a reliable frequency characteristic detection method, resulting in uneven quality of the existing equipment on the market, and reliable performance detection is required before the equipment leaves the factory. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a broadband electromagnetic current transformer applicable to an intelligent integrated switch of a 10 kV distribution network and a performance detection method thereof, so as to overcome the above-mentioned deficiencies in the prior art.

[0006] The technical solution of the present invention for solving the above technical problem is as follows: A broadband electromagnetic current transformer applicable to an intelligent integrated switch of a 10 kV distribution network includes a primary current transformer and a secondary current transformer;

[0007] The primary current transformer includes a shielding case, lead wires, and a magnetic core disposed within the shielding case; the magnetic core includes a skeleton, a metal ring strip, and an enameled wire, and the metal ring strip is embedded in the skeleton; a ring groove is formed in the shielding case, and a circumferential cutting gap communicating with the ring groove is provided on the inner circumferential wall of the shielding case; one end of the enameled wire is wound around the circumference of the skeleton for one turn and then loops back in a direction opposite to the coil traveling direction; the positive and negative poles of the lead wire are respectively connected to both ends of the enameled wire, and one end of the neutral wire of the lead wire is connected to the inner circle of the shielding case;

[0008] The secondary current transformer includes a first reference layer, a second signal layer, a third signal layer, and a fourth reference layer stacked in sequence;

[0009] One end winding of the primary current transformer is coupled to the power distribution line, and the other end winding forms a loop with one end winding of the secondary current transformer, and the other end winding of the secondary current transformer is connected in series with the source resistor R s in series.

[0010] The beneficial effects of the present invention are: The current transformer of the present application can effectively collect high-frequency transient information generated during the fault process. Its primary current transformer is optimized and designed from aspects such as the magnetic core, winding process, thermal compensation, and electromagnetic interference suppression, greatly improving the bandwidth range, measurement accuracy, and sensitivity of the current transformer. The secondary current transformer adopts a 4-layer PCB design, overcoming the double constraints of high-frequency signal transmission on the winding in the traditional Rogowski coil.

[0011] Based on the above technical solutions, the present invention can be further improved as follows.

[0012] Further, the cross-section of the skeleton is square.

[0013] Further, the ratio of the inner radius to the outer radius of the skeleton is 1:1.2 - 1.3.

[0014] Further, the material of the magnetic core is permalloy.

[0015] Further, the vias of the first reference layer, the fourth reference layer are aligned with those of the second signal layer and the third signal layer.

[0016] Further, the lead wire adopts a shielded twisted pair.

[0017] The present invention also discloses a performance detection method for a broadband electromagnetic current transformer applicable to a 10 kV distribution network intelligent fusion complete switch, used to detect the above current transformer, including the following steps:

[0018] Step S01: Output any waveform to the signal generator;

[0019] Step S02: Amplify and output the original waveform for detection by the high-frequency broadband power amplifier for detection by the current transformer to be measured;

[0020] Step S03: The acquisition card collects the detection data and uploads it to the broadband signal detection system to generate the detected output waveform.

[0021] Step S04: Calculate the similarity between the original waveform and the output waveform through the Pearson waveform similarity comparison algorithm, and evaluate the performance of the current transformer to be measured through the similarity, obtaining excellent products, good products, qualified products, and defective products.

[0022] Furthermore, the specific steps of Step S02 are as follows:

[0023] Select appropriate driver-stage power amplifier tubes and final-stage power amplifier tubes, directly read the attenuation value of the network under test through a fixed attenuator, improve impedance matching, and buffer impedance changes.

[0024] The 1:1 balun is used for power distribution and power combination, and the 1:K balun and capacitors and inductors together constitute a broadband matching network.

[0025] Furthermore, in the Pearson waveform similarity comparison algorithm in Step S04, the calculation formula is as follows:

[0026]

[0027] Among them, ρ is the Pearson correlation coefficient, X and Y respectively represent the output waveform data set and the original waveform data set. respectively represent the average value of the output waveform sampling points and the average value of the original waveform sampling points. ρ is used to measure the similarity between two variables. The closer the value is to 1, the greater the correlation between the two variables; the closer the value is to 0, the smaller the correlation between the two variables.

[0028] Furthermore, the judgment criteria for performance evaluation are specifically defined as:

[0029] f x上升 ≥97%, f x下降 ≥96%, f x整体 ≥96% is an excellent product;

[0030] f x上升 ≥94%, f x下降 ≥93%0, f x整体 ≥93% is a good product;

[0031] f x上升 ≥85%, f x下降 ≥85%, f x整体 ≥85% is a qualified product;

[0032] f x上升 <85%, f x下降 <85%, f x整体 <85% is a defective product;

[0033] Among them, f x上升 represents the rising edge similarity of sensor testing, and f x下降 represents the falling edge similarity of sensor testing, and f x整体 represents the overall similarity of sensor testing. For qualified products, the error reasons need to be analyzed and improved, while defective products are eliminated.

[0034] The beneficial effects of the present invention are as follows: The surge generator can output a large current signal, but the frequency band range is small and does not meet the requirements for broadband testing; while the signal generator can output high-frequency signals, but the amplitude of the output signal is small and cannot be detected by the current transformer. The current test environment is difficult to meet the testing requirements of the traveling wave type primary-secondary integrated switch. The performance detection method of the present application can simulate and output any actual on-site waveform, and then be used for sensor performance testing to control the factory performance of the switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of the present invention;

[0036] Figure 2 is a schematic structural diagram of the skeleton of the primary current transformer of the present invention;

[0037] Figure 3 is a schematic electromagnetic shielding structure diagram of the primary current transformer of the present invention;

[0038] Figure 4 is a schematic electromagnetic compensation structure diagram of the primary current transformer of the present invention;

[0039] Figure 5 is a schematic structural diagram of the secondary current transformer of the present invention;

[0040] Figure 6 is a performance detection flow chart of the current transformer of the present invention;

[0041] Figure 7 is a high-frequency broadband power amplifier implementation flow chart of the present invention;

[0042] Figure 8 is a waveform similarity analysis waveform diagram of the present invention.

[0043] In the drawings, the list of components represented by each reference numeral is as follows:

[0044] 1. Primary current transformer; 11. Shielding case; 111. Ring groove; 112. Circumferential cut gap; 12. Lead wire; 13. Magnetic core; 131. Skeleton; 132. Metal ring belt; 133. Enameled wire; 2. Secondary current transformer; 21. First reference layer; 22. Second signal layer; 23. Third signal layer; 24. Fourth reference layer. DETAILED DESCRIPTION OF THE INVENTION

[0045] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0046] As Figures 1 to 5 shown in the embodiment 1, a broadband electromagnetic current transformer applicable to an intelligent integrated switch for a 10 kV distribution network. The primary side current transformer 1 includes a shielding shell 11, a lead wire 12, and a magnetic core 13 disposed inside the shielding shell 11; the magnetic core 13 includes a skeleton 131, a metal ring belt 132, and an enameled wire 133, and the metal ring belt 132 is embedded in the skeleton 131; the change of the ambient temperature will produce a thermal expansion effect on the transformer coil skeleton 131, resulting in the deterioration of the measurement accuracy and frequency response characteristics of the transformer. When the ambient temperature changes from T0 to T1, theoretically, the relative error of the current output by the primary transformer and the temperature difference satisfy the following relationship:

[0047]

[0048] where Δi is the current measurement error, i is the actual current value, T0 is the standard ambient temperature, T1 is the actual ambient temperature, ξ is the relative error factor. As Figure 2 shown, the present invention embeds a metal ring belt 132 made of non-magnetic material in the skeleton 131. When the temperature changes, the relative error factors generated by the metal ring belt 132 and the magnetic core 13 can cancel each other out, thereby eliminating the influence of temperature change on the sensor measurement.

[0049] A ring groove 111 is formed in the shielding shell 11, and a circumferential cutting gap 112 communicating with the ring groove 111 is provided on the inner circumferential wall of the shielding shell 11;

[0050] One end of the enameled wire 133 is wound around the circumference of the skeleton 131 for one turn and then loops back in the direction opposite to the coil traveling direction; the vertical component of the interfering magnetic field cannot be completely eliminated by electromagnetic shielding. The present invention eliminates its influence by the way of coil looping back. As Figure 4 shown, the looped-back wire is connected in series with the output end of the coil. The vertical component interfering magnetic field will generate induced voltages in opposite directions in the coil and the looped-back wire, thereby canceling each other out; and at this time, the looped-back wire is parallel to the magnetic flux line and will not generate additional induced current, which will not affect the normal measurement of the transformer.

[0051] The positive and negative poles of the lead wire 12 are respectively connected to both ends of the enameled wire 133, and the zero line end of the lead wire 12 is connected to the inner ring of the shielding shell 11; when measuring, the other end of the zero line is connected to the negative pole, which can effectively reduce the interference of the external magnetic field;

[0052] The secondary current transformer 2 includes a first reference layer 21, a second signal layer 22, a third signal layer 23, and a fourth reference layer 24 stacked in sequence;

[0053] One end winding of the primary current transformer 1 is coupled to the distribution line, and the other end winding forms a loop with one end winding of the secondary current transformer 2. The other end winding of the secondary current transformer 2 is in series with the source resistor R s for the FTU to perform signal processing.

[0054] Electromagnetic current transformers are vulnerable to the influence of interfering electromagnetic fields, resulting in more scattered waveforms, which are difficult to completely eliminate at the hardware level and need to be dealt with from the sensing side. The present invention suppresses electromagnetic interference from two aspects: electromagnetic shielding and electromagnetic compensation; the shielding shell 11 is made of copper-aluminum alloy with high magnetic permeability. The semi-closed shell made of copper-aluminum alloy can reduce capacitive coupling and achieve electrostatic and magnetic field shielding. Since the ring groove 111 is opened inside the shielding shell 11 and a closed loop is not formed, the magnetic flux to be measured cannot enter the coil core 13. A metal shielding body is used and reliably grounded. At the same time, a circumferential cutting gap 112 is provided on the inner side of the shielding shell 11 to suppress the circulating current on the shielding shell 11.

[0055] The present invention divides the output current signal of the primary current transformer 1 into two paths, one path takes the low-frequency signal and the other path takes the high-frequency signal. In order to overcome the double constraints of high-frequency signal transmission on the winding in the traditional Rogowski coil and improve the fast transient current measurement ability of the secondary current transformer 2, the secondary current transformer 2 adopts a 4-layer PCB design. As Figure 5 shown, the present invention provides a complete reference plane for the signal winding and integrates the current sensing structure with the primary current output line, thereby realizing the broadband induction of the secondary current transformer 2.

[0056] The current transformer of the present application can effectively collect high-frequency transient information generated during the fault process. The primary current transformer 1 is optimized from aspects such as the magnetic core, winding process, thermal compensation, and electromagnetic interference suppression, greatly improving the bandwidth range, measurement accuracy, and sensitivity of the current transformer. The secondary current transformer 2 adopts a 4-layer PCB design to overcome the double constraints of high-frequency signal transmission on the winding in the traditional Rogowski coil.

[0057] Example 2, this example is a further improvement based on Example 1, and the specific content is as follows:

[0058] The cross-section of the bobbin 131 is square. The cross-sectional area of the bobbin 131 with a square cross-section is increased by 1.3 times compared with the traditional circular structure, and the inductance of the transformer is proportional to its cross-sectional area, so the inductance is also increased to 1.3 times. Therefore, the response speed of the sensor is improved, and the measurement accuracy is also slightly improved.

[0059] Embodiment 3 is a further improvement based on Embodiment 1, and the specific content is as follows:

[0060] The inner-to-outer radius ratio of the bobbin 131 is 1:1.2 to 1.3. When the radius of the bobbin 131 of the coil of the primary current transformer 1 itself is much larger than the diameter of the cross-section of the bobbin 131, the total magnetic flux in the coil is basically the same as the magnetic field strength passing through the cross-section. When measuring the current of the conductor to be measured, the position of the conductor to be measured should be able to be placed arbitrarily, so that the magnetic field strength on the cross-section of the bobbin 131 can be basically the same everywhere. In this case, the inner-to-outer radius ratio of the bobbin 131 should be between 1:1.2 and 1.3; in specific implementation, the inner diameter a of the bobbin 131 is selected to be 7.55 cm, the outer diameter b is 9.15 cm, and the cross-section height h is 1 cm; the self-inductance and mutual inductance of the transformer are positively correlated with the wire diameter of the enameled wire 133. In theory, the larger the wire diameter, the higher the accuracy of the transformer and the wider the frequency band range. However, the increase in wire diameter will cause difficulties in winding the coil and an increase in the wire turn gap, which will instead lead to a decrease in accuracy. Combining with the design parameters of the bobbin 131, the enameled wire 133 made of 0.9 mm pure copper material is selected, and the coil is wound by semi-conductive crimped paper instead of manual wrapping, which can reduce the objective error caused by manual wrapping and achieve the balance of wire diameter and wire turn gap.

[0061] Embodiment 4 is a further improvement based on Embodiment 1, and the specific content is as follows:

[0062] The material of the magnetic core 13 is permalloy. Permalloy has a higher magnetic permeability in a weak magnetic field and has stronger weak current recognition ability compared with the silicon steel body, iron crystal, and nanocrystalline used in traditional transformers, and is suitable for detecting high-resistance (>1 kΩ) grounding faults in the distribution network.

[0063] Embodiment 5 is a further improvement based on Embodiment 1, and the specific content is as follows:

[0064] The vias of the first reference layer 21, the fourth reference layer 24 are aligned with the vias of the second signal layer 22 and the third signal layer 23. Thus, the shortest winding return loop can be obtained.

[0065] Embodiment 6 is a further improvement based on Embodiment 1, and the specific content is as follows:

[0066] The lead wire 12 uses shielded twisted pair. It can effectively prevent the influence of external high-frequency magnetic fields on the output signal during measurement.

[0067] As Figures 6 to 8As shown in the figure, Embodiment 7 is a performance detection method for a broadband electromagnetic current transformer applicable to an intelligent integrated switch of a 10 kV distribution network, which is used to detect the current transformer in any one of Embodiments 1 to 6, and includes the following steps:

[0068] Step S01: Output any waveform to the signal generator; specifically, in implementation, the upper computer outputs any waveform to the signal generator, and this signal is immediately output, or is output to the signal generator at a time specified by the GPS timing module;

[0069] Step S02: The original waveform for detection is amplified and output by the high-frequency broadband power amplifier for detection by the current transformer to be tested;

[0070] Step S03: The acquisition card acquires the detection data and uploads it to the broadband signal detection system to generate the output waveform after detection;

[0071] Step S04: Calculate the similarity between the original waveform and the output waveform through the waveform similarity comparison algorithm of Pearson, and evaluate the performance of the current transformer to be tested through the similarity to obtain excellent products, good products, qualified products, and defective products.

[0072] The surge generator can output a large current signal, but the frequency band range is small and does not meet the requirements for broadband testing; while the signal generator can output high-frequency signals, but the amplitude of the output signal is small and cannot be detected by the current transformer. The current test environment is difficult to meet the test requirements of the traveling wave type primary-secondary integrated switch. The performance detection method of this application can simulate and output any actual on-site waveform, and then be used for sensor performance testing to control the factory performance of the switch.

[0073] Embodiment 8 is a further improvement based on Embodiment 7, and is specifically as follows:

[0074] The specific steps of Step S02 are as follows:

[0075] Use a balun to convert the signal from the balanced transmission mode of the coaxial cable to the unbalanced transmission mode, or from the unbalanced transmission mode to the balanced transmission mode, to realize the transmission of the signal between different circuits, which can solve the broadband matching problem that cannot meet the requirements of centralized component matching, and enable the power amplifier to obtain a large output power and gain throughout the frequency band;

[0076] Select appropriate driver stage power amplifier tubes and final stage power amplifier tubes, and directly read the attenuation value of the measured network through a fixed attenuator, improve impedance matching, and buffer impedance changes;

[0077] The 1:1 balun is used for power distribution and power synthesis, and the 1:K balun and capacitors and inductors together constitute a broadband matching network, and finally realize K-fold amplification of the input signal.

[0078] Example 9. This example is a further improvement based on Example 7, which is specifically as follows:

[0079] For the Pearson waveform similarity comparison algorithm in step S04, the calculation formula is as follows:

[0080]

[0081] where ρ is the Pearson correlation coefficient, X and Y respectively represent the output waveform data set and the original waveform data set, respectively represent the average value of the output waveform sampling points and the average value of the original waveform sampling points. ρ is used to measure the similarity between two variables. The closer the value is to 1, the greater the correlation between the two variables; the closer the value is to 0, the smaller the correlation between the two variables.

[0082] Example 10. This example is a further improvement based on Example 9, which is specifically as follows:

[0083] The judgment criteria for performance evaluation are specifically defined as:

[0084] f x上升 ≥97%, f x下降 ≥96%, f x整体 ≥96%, which is considered an excellent product;

[0085] f x上升 ≥94%, f x下降 ≥93%, f x整体 ≥93%, which is considered a good product;

[0086] f x上升 ≥85%, f x下降 ≥85%, fx 整体 ≥85%, which is considered a qualified product;

[0087] f x上升 <85%, f x下降 <85%, f x整体 <85%, which is considered a defective product;

[0088] where f x上升 represents the similarity of the rising edge of the sensor test, f x下降 represents the similarity of the falling edge of the sensor test, f x整体 represents the overall similarity of the sensor test. For qualified products, the error reasons need to be analyzed and improved, while defective products are eliminated.

[0089] The present invention respectively selects the rising edge of the waveform, the falling edge of the waveform and the overall similarity of the waveform for performance evaluation and analysis, as Figure 8As shown, the rising edge period of the waveform is from the start time of waveform recording to the time when the waveform drops to 3 / 4 of the peak value of the first wave, mainly reflecting the high-frequency (≥100 kHz) characteristics of the sensor; the falling edge period is the remaining period of the waveform except for the rising edge, mainly reflecting the low-frequency characteristics (≤10 kHz) of the sensor.

[0090] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A broadband electromagnetic current transformer applicable to an intelligent integrated switch for a 10 kV distribution network, characterized in that, It includes a primary current transformer (1) and a secondary current transformer (2); The primary current transformer (1) includes a shielding case (11), a lead wire (12), and a magnetic core (13) disposed within the shielding case (11); the magnetic core (13) includes a framework (131), a metal ring belt (132), and an enameled wire (133), and the metal ring belt (132) is embedded in the framework (131); a ring groove (111) is formed in the shielding case (11), and a circumferential cutting gap (112) communicating with the ring groove (111) is provided on the inner circumferential wall of the shielding case (11); one end of the enameled wire (133) is wound around the framework (131) in the circumferential direction for one turn and then loops back in the direction opposite to the coil traveling direction; the positive and negative poles of the lead wire (12) are respectively connected to both ends of the enameled wire (133), and the zero - line end of the lead wire (12) is connected to the inner ring of the shielding case (11); The secondary current transformer (2) includes a first reference layer (21), a second signal layer (22), a third signal layer (23), and a fourth reference layer (24) stacked in sequence; One end winding of the primary current transformer (1) is coupled to the distribution line, and the other end winding forms a loop with one end winding of the secondary current transformer (2). The other end winding of the secondary current transformer (2) is in series with the source resistance R s in series; The method for detecting a current transformer includes the following steps: Step S01: Output an arbitrary waveform to a signal generator; Step S02: Amplify and output the original waveform for detection by a high - frequency broadband power amplifier for the current transformer under test to be detected; Step S03: Collect detection data by a data acquisition card and upload it to a broadband signal detection system to generate an output waveform after detection; Step S04: Calculate the similarity between the original waveform and the output waveform through the Pearson waveform similarity comparison algorithm, and evaluate the performance of the current transformer under test through the similarity to obtain excellent products, good products, qualified products, and defective products.

2. The broadband electromagnetic current transformer for an intelligent integrated switch applicable to a 10 kV distribution network according to claim 1, wherein The cross - section of the framework (131) is square.

3. The broadband electromagnetic current transformer for the intelligent integrated switchgear applicable to the 10 kV distribution network according to claim 2, characterized in that The ratio of the inner radius to the outer radius of the framework (131) is 1:1.2 - 1.

3.

4. The broadband electromagnetic current transformer for the intelligent integrated switch applicable to 10 kV distribution network according to claim 1, characterized in that, The material of the magnetic core (13) is permalloy.

5. A broadband electromagnetic current transformer applicable to an intelligent integrated switch for a 10 kV distribution network according to claim 1, characterized in that, The via holes of the first reference layer (21), the fourth reference layer (24) are aligned with those of the second signal layer (22) and the third signal layer (23).

6. The broadband electromagnetic current transformer for the intelligent integrated switchgear applicable to 10 kV distribution network according to claim 1, characterized in that, The lead wire (12) uses shielded twisted - pair wires.

7. The broadband electromagnetic current transformer for the intelligent integrated switchgear applicable to the 10 kV distribution network according to claim 1, characterized in that, The specific steps of Step S02 are as follows: Select appropriate driver - stage power - amplifier tubes and final - stage power - amplifier tubes, directly read the attenuation value of the measured network through a fixed attenuator, improve impedance matching, and buffer impedance changes; A 1:1 balun is used for power distribution and power synthesis, and a 1:K balun and capacitors and inductors together constitute a broadband matching network.

8. A broadband electromagnetic current transformer for an intelligent integrated switch applicable to a 10 kV distribution network according to claim 1, characterized in that, For the Pearson waveform similarity comparison algorithm in Step S04, the calculation formula is as follows: Among them, ρ is the Pearson correlation coefficient, and X and Y respectively represent the output waveform data set and the original waveform data set. They respectively represent the average value of the output waveform sampling points and the average value of the original waveform sampling points. ρ is used to measure the similarity between two variables. The closer the value is to 1, the greater the correlation between the two variables; the closer the value is to 0, the smaller the correlation between the two variables.

9. The broadband electromagnetic current transformer for the intelligent integrated switch applicable to 10 kV distribution network according to claim 8, characterized in that, The judgment criteria for the performance evaluation are specifically defined as: f x上升 ≥97%, f x下降 ≥96%, f x整体 ≥96% is considered as high-quality product; f x上升 ≥94%, f x下降 ≥93%, f x整体 ≥93%, that is, a good product; f x上升 ≥85%, f x下降 ≥85%, f x整体 ≥85% is a qualified product; f x上升 <85%, f x下降 <85%, f x整体 <85% is a defective product; Among them, f x上升 represents the rising edge similarity of sensor testing, f x下降 represents the falling edge similarity of sensor testing, f x整体 represents the overall similarity of sensor testing. For qualified products, the error causes need to be analyzed and improvements made, while defective products are eliminated.

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