A roebel bar system for feeder terminal unit travel time ranging

Abstract

A Rogowski coil system for feeder terminal unit traveling wave ranging belongs to the technical field of Rogowski coils. It comprises a Rogowski coil, a conditioning circuit connected to the output end of the Rogowski coil, the input end of the conditioning circuit connected to the Rogowski coil, and the output end of the conditioning circuit connected to the feeder terminal unit. The conditioning circuit comprises a frequency band segmentation module for segmenting the signal of the Rogowski coil into multiple sub-frequency bands of different frequency ranges, the input end of the frequency band segmentation module connected to the output end of the Rogowski coil, and the output end of the frequency band segmentation module connected to the feeder terminal unit. In the Rogowski coil system for feeder terminal unit traveling wave ranging, the signal of the Rogowski coil is segmented into multiple sub-frequency bands of different frequency ranges by the frequency band segmentation module, which facilitates the feeder terminal unit to adjust the gain of the signals of different frequency bands, dynamically match the signal characteristics of each frequency band, and extract mA-level traveling wave signals in the 1kHz-5MHz frequency band.

Description

Technical Field

[0001] A Rogowski coil system for traveling wave ranging in feeder terminal units belongs to the field of Rogowski coil technology. Background Technology

[0002] With the rapid development of the power industry, it has shifted from traditional power distribution to automated power distribution. Monitoring the operational status of primary equipment along overhead cables is crucial, ensuring the reliability of power supply in automated distribution systems. This significantly reduces the workload of line inspections and saves on engineering maintenance costs. It also facilitates the rapid identification of fault points, enabling timely handling of on-site problems and rapid restoration of power.

[0003] When monitoring the operating status of overhead cables, traveling wave current signals are an important parameter. In existing technologies, using Rogowski coils for power frequency current acquisition is a common method in this field. Traveling wave ranging is a key technology for fault location in power distribution systems, relying on the detection of high-frequency transient signals. While traditional Rogowski coils can effectively measure broadband currents, they lack the mA-level traveling wave detection sensitivity required for FTU applications. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a Rogowski coil system for feeder terminal unit traveling wave ranging that divides the signal of the Rogowski coil into multiple sub-bands with different frequency ranges through a frequency band segmentation module, so as to facilitate the feeder terminal unit to realize segmented gain adjustment of signals in different frequency bands, dynamically match the signal characteristics of each frequency band, and extract mA-level traveling wave signals in the 1kHz-5MHz frequency band.

[0005] The technical solution adopted by this utility model to solve its technical problem is as follows: the Rogowski coil system for traveling wave ranging of a feeder terminal unit includes a Rogowski coil and a conditioning circuit connected to the output end of the Rogowski coil. The Rogowski coil is connected to the input end of the conditioning circuit, and the output end of the conditioning circuit is connected to the feeder terminal unit. The conditioning circuit includes a frequency band segmentation module for dividing the signal of the Rogowski coil into multiple sub-bands with different frequency ranges. The output end of the Rogowski coil is connected to the input end of the frequency band segmentation module, and the output end of the frequency band segmentation module is connected to the feeder terminal unit.

[0006] Preferably, the conditioning circuit also includes a high-frequency filter circuit and a differential amplifier circuit. The output terminal of the Rogowski coil is connected to the input terminal of the high-frequency filter circuit, the output terminal of the high-frequency filter circuit is connected to the input terminal of the differential amplifier circuit, and the output terminal of the differential amplifier circuit is connected to the input terminal of the frequency band segmentation module.

[0007] Preferably, the frequency band segmentation module includes multiple bandpass filters arranged in parallel.

[0008] Preferably, the Rogowski coil includes an annular coil frame, a secondary coil wound on the coil frame, a primary coil mutually inducted with the secondary coil at the coil frame, and a magnetic core inside the coil frame. The magnetic core includes multiple magnetic core segments spaced apart, with an air gap formed between any two adjacent magnetic core segments.

[0009] Preferably, the width of the air gap is 0.1mm to 0.5mm.

[0010] Preferably, the secondary coil has two coil connectors leading out from the surface of the coil frame as the output terminals of the Rogowski coil, and the two coil connectors are spaced apart on the surface of the coil frame.

[0011] Preferably, the distance between the two coil connectors on the surface of the coil frame is 1~2mm.

[0012] Preferably, a shielding layer is also wound around the surface of the coil frame, and the shielding layer encloses the secondary coil.

[0013] Preferably, the shielding layer is grounded.

[0014] Preferably, the coil bobbin includes a housing with a groove inside the housing for accommodating the magnetic core.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] In the Rogowski coil system for traveling wave ranging of the feeder terminal unit in this application, the signal of the Rogowski coil is divided into multiple sub-bands with different frequency ranges by a frequency band segmentation module. This facilitates the feeder terminal unit to perform segmented gain adjustment on signals of different frequency bands and dynamically match the signal characteristics of each frequency band, so as to extract mA-level traveling wave signals in the 1kHz-5MHz frequency band.

[0017] In this application, the width of the air gap opening between the individual magnetic core units is 0.1mm~0.5mm, which balances the permeability and flux density, enhances the coil's ability to sense weak currents, and maintains a wide bandwidth response. It also increases the reluctance, reduces the nonlinear effect of the magnetic core, effectively prevents saturation at high frequencies (5MHz) or high currents at power frequency, and ensures the linear output of the Rogowski coil.

[0018] The starting position of the secondary coil, i.e., the junction of the two coils, is the region with the strongest electric field coupling. Because the potential difference between the starting and ending turns is large, it is easy to form a large parasitic capacitance. By setting a spacing of 1~2mm, the physical distance between the starting and ending turns is increased, the electric field strength is reduced, thereby reducing the distributed capacitance at the starting and ending positions, improving the fidelity of high-frequency transient signals, and making it suitable for the traveling wave ranging requirements of feeder terminal units.

[0019] The grounded shielding layer, after grounding, forms an equipotential shield, isolating external electric fields, reducing parasitic capacitance between the secondary coil and the environment, and simultaneously shielding against high-frequency electromagnetic interference in the power distribution network. The shielding layer, in conjunction with the multi-segment structure of the magnetic core, achieves a synergistic effect, reducing noise interference and enabling fault location accuracy to reach ±0.5m. Attached Figure Description

[0020] Figure 1 This is a front view of the Rogowski coil in a Rogowski coil system used for traveling wave ranging in a feeder terminal unit.

[0021] Figure 2 for Figure 1 It is the right view.

[0022] Figure 3 for Figure 2 Sectional view along the AA direction.

[0023] Figure 4 This is a block diagram of the control circuit principle of the Rogowski coil system used for traveling wave ranging in feeder terminal units.

[0024] Figure 5 This is the equivalent circuit diagram of a Rogowski coil.

[0025] The components are: 1. Coil connector; 2. Shielding layer; 3. Primary coil; 4. Secondary coil; 5. Coil frame; 6. Magnetic core; 7. Outer shell. Detailed Implementation

[0026] Figures 1-5 This is the preferred embodiment of the present invention, which is described below in conjunction with the appendix. Figures 1-5 The present invention will be further described below.

[0027] A Rogowski coil system for traveling wave ranging in a feeder terminal unit (hereinafter referred to as the Rogowski coil system) includes a Rogowski coil and a control circuit connected to the signal output terminal of the Rogowski coil. Figures 1-2 As shown, the Rogowski coil includes a circular coil frame 5, on which a secondary coil 4 is wound. A primary coil 3 is also provided. When the primary coil 3 has one turn, it can pass directly through the central hole of the coil frame 5. If the primary coil 3 has multiple turns, it is also wound on the coil frame 5, and in this case, the primary coil 3 is symmetrically or evenly wound on the coil frame 5.

[0028] The coil frame 5 includes a housing 7 and a magnetic core 6 disposed within the housing 7. The magnetic core 6 comprises multiple magnetic core units of the same size, evenly arranged along the contour of the housing 7. Each magnetic core unit comprises 3 to 6 segments, preferably using... Figure 3The four segments shown represent individual magnetic core units, each with a fan-shaped structure and a central angle of 45°. Magnetic core 6 is made of high-permeability ferrite or nanocrystalline alloy.

[0029] A groove for accommodating the magnetic core 6 is provided inside the outer casing 7. The four magnetic core segments are arranged opposite each other inside the outer casing 7. After the four magnetic core segments are fixed inside the outer casing 7, an opening is formed between the ports on the same side of any two adjacent magnetic core segments. In this Rogowski coil system, the width of the opening is 0.1mm to 0.5mm, preferably 0.3mm, which balances the permeability and magnetic flux density, enhances the coil's ability to sense weak currents, and maintains a wide bandwidth response.

[0030] By arranging a magnetic core 6 in the Rogowski coil, and the magnetic core 6 comprising four spaced magnetic core units, the four air gaps formed by the spaced magnetic core units increase the magnetic reluctance, reduce the nonlinear effect of the magnetic core 6, effectively prevent saturation under high frequency (5MHz) or power frequency high current, and ensure the linear output of the Rogowski coil.

[0031] The effective permeability can be reduced to 10~100, making the magnetic core 6 almost a non-magnetic core, ensuring that the output voltage and current change rate are strictly proportional. At the same time, the multi-segment structure of the magnetic core 6 concentrates the magnetic flux, enhancing the sensitivity to 1mA traveling wave signals, with a signal-to-noise ratio of 20dB.

[0032] The secondary coil 4 uses enameled wire with a diameter ≥2UEW-0.2, and is wound evenly on a ring-shaped frame with 200~400 turns. After the secondary coil 4 is wound on the surface of the coil frame 5, a set of coil connectors 1 are led out from the side of the coil frame 5 as the output terminals of the secondary coil 4. When winding the secondary coil 4 on the surface of the coil frame 5, the two coil connectors 1 of the secondary coil 4 do not overlap on the circumference of the coil frame 5. That is, when winding the secondary coil 4, after identifying one of the coil connectors 1 as the starting point and starting the winding along the circumference of the coil frame 5 from the starting point position, the coil connector 1 at the end point does not cross the coil connector 1 at the starting point. The two coil connectors 1 led out from the coil frame 5 are spaced 1~2mm apart.

[0033] As is generally known in this field, the starting position of the secondary coil 4 (i.e., at the junction of the two coils 1) is the region with the strongest electric field coupling because the potential difference between the starting and ending turns is large, which easily leads to a large parasitic capacitance. By setting a spacing of 1~2mm, the physical distance between the starting and ending turns is increased, the electric field strength is reduced, thereby reducing the distributed capacitance at the starting and ending positions.

[0034] Therefore, arranging the two connectors 1 at intervals reduces the distributed capacitance, according to the cutoff frequency formula: f H=1 / (2*π*R*C0) shows that by reducing the distributed capacitance C0, the upper cutoff frequency is increased, thereby improving the fidelity of high-frequency signals from 1kHz to 5MHz.

[0035] Further derived from the formula for the resonant frequency of the secondary coil 4 f From r=1 / (2*π*sqrt(L*C0), it can be seen that reducing the capacitance C0 can significantly increase the resonant frequency of the secondary coil 4. This makes the secondary coil more efficient in the 1kHz~5MHz frequency band. Experimental data shows that the 1~2mm spacing between the two coil connectors 1 reduces the distributed capacitance by about 30%, improving the fidelity of high-frequency transient signals and meeting the requirements of traveling wave ranging in feeder terminal units (FTUs).

[0036] After the secondary coil 4 is wound, a shielding layer 2 is installed outside the secondary coil 4. The shielding layer 2 is preferably made of copper foil. During the winding process along the coil frame 5, the shielding layer 2 completely encloses the secondary coil 4. The shielding layer 2 adopts a grounded structure. After grounding, the shielding layer 2 forms an equipotential shield, isolating external electric fields, reducing parasitic capacitance between the secondary coil 4 and the environment, and simultaneously shielding against high-frequency electromagnetic interference in the power distribution network. The shielding layer 2, in conjunction with the multi-segment structure of the magnetic core 6, achieves a synergistic effect, reducing noise interference and enabling fault location accuracy to reach ±0.5m.

[0037] like Figure 4 As shown, the control circuit of this Rogowski coil system includes a high-pass filter circuit connected to the output terminal of the Rogowski coil (coil connector 1). The output terminal of the high-pass filter circuit is connected to the input terminal of a differential amplifier circuit. The output terminal of the differential amplifier circuit is connected to the input terminal of a frequency band segmentation module. The output terminal of the frequency band segmentation module is connected to a feeder termination unit (FTU). Further combining... Figure 5 The Rogowski coil equivalent circuit shown has coil L1 (primary coil 3) and coil L2 (secondary coil 4) mutually inducted with a mutual inductance coefficient of M. One end of coil L2 is connected in series with the equivalent inductance L0 and the internal resistance R0, and is simultaneously connected to one end of the inter-turn capacitance C0 and one end of the load R1. The other end of coil L2 is simultaneously connected to the other end of the distributed capacitance C0 and the other end of the load R1.

[0038] The high-pass filter circuit and differential amplifier circuit both employ well-known circuit structures in the field, and will not be described in detail here. The input terminal of the high-pass filter circuit is connected in parallel across the load R1. The band segmentation module is implemented using multiple band-pass filter circuits connected in parallel, which achieves the function of band segmentation.

[0039] The 1kHz–5MHz frequency band acquired by the Rogowski coil is divided into several sub-bands: the low-frequency band (power frequency harmonics and low-frequency transients) between 1kHz and 10kHz; the mid-frequency band (the main frequency range of typical traveling wave signals) between 10kHz and 500kHz; and the high-frequency band (high-frequency transients and spike pulses) between 500kHz and 5MHz.

[0040] Then, the signals of different frequency bands are sent to the feeder termination unit (FTU) respectively, so that the feeder termination unit (FTU) can design different gain adjustments for each frequency band: increase the gain for the low frequency band to compensate for the low frequency attenuation of the integrator; maintain a flat gain for the mid frequency band to ensure the fidelity of the traveling wave signal's main frequency range; and appropriately reduce the gain for the high frequency band to prevent high frequency noise amplification.

[0041] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from its technical solution shall still fall within the protection scope of this utility model.

Claims

1. A Rogowski coil system for traveling wave ranging in a feeder termination unit, comprising a Rogowski coil and a conditioning circuit connected to the output terminal of the Rogowski coil, wherein the Rogowski coil is connected to the input terminal of the conditioning circuit, and the output terminal of the conditioning circuit is connected to the feeder termination unit, characterized in that: The conditioning circuit includes a band segmentation module for dividing the signal from the Rogowski coil into multiple sub-bands with different frequency ranges. The output terminal of the Rogowski coil is connected to the input terminal of the band segmentation module, and the output terminal of the band segmentation module is connected to the feeder termination unit.

2. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 1, characterized in that: The conditioning circuit also includes a high-frequency filter circuit and a differential amplifier circuit. The output terminal of the Rogowski coil is connected to the input terminal of the high-frequency filter circuit, the output terminal of the high-frequency filter circuit is connected to the input terminal of the differential amplifier circuit, and the output terminal of the differential amplifier circuit is connected to the input terminal of the frequency band segmentation module.

3. The Rogowski coil system for traveling wave ranging of a feeder terminal unit according to claim 1 or 2, characterized in that: The frequency band segmentation module includes multiple bandpass filters connected in parallel.

4. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 1, characterized in that: The Rogowski coil includes a ring-shaped coil frame (5), a secondary coil (4) wound on the coil frame (5), and a primary coil (3) that is mutually inductive with the secondary coil (4) is also provided at the coil frame (5). A magnetic core (6) is provided inside the coil frame (5). The magnetic core (6) includes multiple magnetic core units arranged at intervals, and an air gap is formed between any two adjacent magnetic core units.

5. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 4, characterized in that: The width of the air gap is 0.1mm~0.5mm.

6. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 4, characterized in that: The secondary coil (4) has two coil connectors (1) leading out from the surface of the coil frame (5) as the output end of the Rogowski coil. The two coil connectors (1) are spaced apart on the surface of the coil frame (5).

7. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 6, characterized in that: The distance between the two coil connectors (1) on the surface of the coil frame (5) is 1~2mm.

8. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 4, characterized in that: A shielding layer (2) is also wound around the surface of the coil frame (5), which encloses the secondary coil (4).

9. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 8, characterized in that: Shielding layer (2) is grounded.

10. The Rogowski coil system for traveling wave ranging in a feeder terminal unit according to claim 4, characterized in that: The coil frame (5) includes a housing (7) with a groove inside the housing (7) for accommodating the magnetic core (6).

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