Resistance type straight head phase and zero sequence integrated three-phase sensor for ring main unit

Abstract

The utility model discloses a resistance type straight head phase zero sequence integrated three-phase sensor for a ring main unit, which comprises an A-phase circuit, a B-phase circuit and a C-phase circuit, and each phase circuit comprises a primary high-voltage part and a secondary low-voltage part; the primary high-voltage part comprises a primary high-voltage resistor, and the input end of the primary high-voltage resistor is connected with the power supply end; the secondary low-voltage part comprises a secondary capacitor, a secondary resistor and a phase zero sequence isolation transformer, the secondary capacitor and the secondary resistor are connected in parallel, a small voltage signal output after parallel connection is input into the phase zero sequence isolation transformer, and two paths of signals are output through the phase zero sequence isolation transformer and comprise a path of phase sequence signal and a path of zero sequence signal. The device is simple in structure and small in size, integrates three-phase voltage sampling, measurement, protection, phase sequence and zero sequence functions, and is suitable for intelligent reconstruction and upgrading of power distribution equipment.

Description

Technical Field

[0001] The utility model relates to the field of automatic sampling control of power system distribution network, in particular to a resistance-type straight-end phase zero-sequence integrated three-phase sensor for a ring network cabinet. Background Art

[0002] With the development of smart grids, ring main units (RMUs), crucial equipment for segmenting, branching, demarcating, and connecting distribution networks, need to feature adaptive, integrated local feeder automation to coordinate primary and secondary closing of substation outgoing line switches. Currently, RMUs primarily utilize traditional electromagnetic voltage transformers, but their drawbacks are becoming increasingly apparent with the development of smart grids.

[0003] In applications where ring main units integrate primary and secondary circuits, traditional electromagnetic voltage transformers can burn out due to magnetic saturation when a short circuit occurs in the system, causing damage to the equipment and potentially posing a threat to personal safety. Furthermore, traditional electromagnetic voltage transformers have a narrow frequency response range, poor linearity, weak anti-interference capabilities, and a limited dynamic measurement range, making them difficult to meet the needs of wide-range measurements. Furthermore, traditional electromagnetic voltage transformers are large, heavy, and have high inherent losses, which not only increases the difficulty of installation and maintenance but also increases operating costs. The need for secondary conversion in connections with relay protection and automation instruments can lead to device mismatches, increasing system complexity and potential points of failure. Utility Model Content

[0004] The purpose of the utility model is to provide a small-sized and fully functional resistance-type straight-end phase-zero-sequence integrated three-phase sensor for a ring network cabinet, which provides a stable and accurate voltage acquisition signal for a distribution terminal unit.

[0005] In order to solve the above technical problems, the utility model provides a resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinets, including A-phase, B-phase and C-phase circuits, each phase circuit includes a primary high-voltage part and a secondary low-voltage part;

[0006] The primary high-voltage part includes a primary high-voltage resistor, and the input end of the primary high-voltage resistor is connected to the power supply end;

[0007] The secondary low-voltage part includes a secondary capacitor, a secondary resistor and a phase zero-sequence isolation transformer. The secondary capacitor and the secondary resistor are connected in parallel. The small voltage signal output after parallel connection is input into the phase zero-sequence isolation transformer, and two signals are output through the phase zero-sequence isolation transformer, including one phase sequence signal and one zero-sequence signal.

[0008] Furthermore, the primary high-voltage resistor adopts a columnar non-inductive high-precision thick film resistor.

[0009] Furthermore, the secondary low-voltage part also includes an inductor, and the inductor is connected in series with the phase zero-sequence isolation transformer.

[0010] Furthermore, the secondary resistor includes a secondary low-voltage resistor and a secondary adjustable resistor connected in series.

[0011] Furthermore, the phase zero-sequence isolation transformer is provided with a phase-sequence voltage output terminal and a zero-sequence voltage output terminal, and each of the zero-sequence voltage output terminals of the A-phase, B-phase and C-phase circuits are interconnected to form an open triangle, and the open triangle outputs a three-phase zero-sequence voltage signal.

[0012] Furthermore, it also includes a signal transmission component; the signal transmission component includes a primary high-voltage line cap, a primary high-voltage line, a secondary low-voltage line and a circuit board; the primary high-voltage line cap is sleeved on the primary high-voltage line, and the input end of the primary high-voltage resistor is connected to the power supply end through the primary high-voltage line; the primary high-voltage part and the secondary low-voltage part are connected through the secondary low-voltage line; the secondary low-voltage part is installed on the circuit board.

[0013] Furthermore, the signal transmission component also includes a five-core shielded twisted pair cable; the output end of the secondary low-voltage part outputs a three-phase zero-sequence voltage signal through the five-core shielded twisted pair cable.

[0014] Furthermore, it also includes an installation component; the installation component includes a stainless steel base, support studs and mounting holes; the primary high-voltage resistor is installed on the stainless steel base; the circuit board is installed in the stainless steel base through the support studs; the three-phase sensor is connected to other equipment through the mounting holes.

[0015] Furthermore, it also includes a sealing component; the sealing component includes epoxy resin, a sealing ring and sealing silicone; the epoxy resin encapsulates the primary high-voltage resistor; the sealing silicone seals the secondary low-voltage part; the sealing ring is installed at the junction of the stainless steel base and the primary high-voltage resistor.

[0016] Furthermore, the secondary capacitor is a monolithic secondary capacitor.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] The utility model can work stably under high voltage conditions and output small voltage signals by introducing a primary high-voltage resistor; the secondary low-voltage part is provided with a secondary capacitor, a secondary resistor and a phase zero-sequence isolation transformer, which realizes the separate output of phase and zero-sequence voltage signals, and realizes the three-phase voltage sampling, measurement, protection, phase sequence and zero sequence functions, and is suitable for distribution equipment such as ring network cabinets. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a circuit diagram of a resistor-type straight-end phase zero-sequence integrated three-phase sensor for a ring network cabinet in one embodiment of the present utility model;

[0020] Figure 2 This is a schematic structural diagram of a resistor-type straight-end phase zero-sequence integrated three-phase sensor for a ring network cabinet in one embodiment of the present invention;

[0021] Figure 3 This is a side view of a resistor-type straight-end phase-zero-sequence integrated three-phase sensor for a ring main unit in one embodiment of the present utility model;

[0022] Figure 4 It is a top view of a resistor-type straight-end phase-zero-sequence integrated three-phase sensor for a ring network cabinet in one embodiment of the present utility model.

[0023] Figure numbers: 1. Primary high-voltage line cap; 2. Primary high-voltage line; 3. Epoxy resin; 4. Primary high-voltage resistor; 5. Secondary low-voltage line; 6. Sealing ring; 7. Stainless steel base; 8. Five-core shielded twisted-pair cable; 9. Mounting hole; 10. Support stud; 11. Phase zero-sequence isolation transformer; 12. Circuit board; 13. Secondary resistor; 14. Secondary capacitor; 15. Sealing silicone. DETAILED DESCRIPTION

[0024] The following schematic diagram provides a more detailed description of the resistor-type, direct-phase, zero-sequence, integrated three-phase sensor for a ring main unit (RMU) according to the present invention. This diagram illustrates a preferred embodiment of the present invention. It should be understood that those skilled in the art may modify the present invention as described herein while still achieving its advantageous effects. Therefore, the following description should be understood as a general guide for those skilled in the art and not as a limitation of the present invention.

[0025] The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0026] like Figures 1 to 4 As shown, an embodiment of the present invention proposes a resistance-type straight-end phase zero-sequence integrated three-phase sensor for a ring network cabinet, including phase A, phase B and phase C circuits, and each phase circuit includes a primary high-voltage part and a secondary low-voltage part.

[0027] Specifically, the primary high-voltage circuit comprises a primary high-voltage resistor 4, whose input is connected to the power supply. This resistor is used to output a small voltage signal and reduce the impact of high voltage on the secondary low-voltage circuit. This resistor is a columnar, non-inductive, high-precision thick-film resistor suitable for use at 20kV. When operating outdoors at -40°C to +70°C, it exhibits a low temperature drift coefficient, a constant error range, and strong anti-interference capabilities, thereby improving the stability of the output signal.

[0028] The secondary low-voltage part includes a secondary capacitor 14, a secondary resistor 13 and a phase zero-sequence isolation transformer 11. The secondary resistor 13 and the secondary capacitor 14 are connected in parallel, and the output end of the parallel connection is connected to the phase zero-sequence isolation transformer 11. The small voltage signal output by the secondary resistor 13 and the secondary capacitor 14 after being connected in parallel is input into the phase zero-sequence isolation transformer 11, and two signals are output through the phase zero-sequence isolation transformer 11, including one phase sequence signal and one zero-sequence signal.

[0029] In a specific embodiment, the secondary low-voltage part also includes an inductor, which is connected in series with the phase zero-sequence isolation transformer 11, and the input end of the inductor connected in series with the phase zero-sequence isolation transformer 11 is connected to the output end of the secondary resistor 13 and the secondary capacitor 14 connected in parallel.

[0030] In this embodiment, the secondary capacitor 14 is a monolithic secondary capacitor, which utilizes the advantages of the monolithic secondary capacitor, such as small size, good stability, and high temperature resistance, to adjust the phase difference and maintain signal stability, thereby ensuring the normal operation of the circuit. The secondary resistor 13 includes a secondary low-voltage resistor and a secondary adjustable resistor connected in series, and the secondary low-voltage resistor and the secondary adjustable resistor are connected in series. The secondary low-voltage resistor has good stability and reliability and is used to provide a stable reference resistance value; while the secondary adjustable resistor accurately adjusts the resistance value to accurately control the current or voltage in the circuit. The combination of the two accurately outputs the required signal and enables the circuit to maintain good performance during long-term operation.

[0031] In a preferred embodiment, the phase-to-zero-sequence isolation transformer 11 is provided with a phase-to-sequence voltage output terminal and a zero-sequence voltage output terminal. Each of the zero-sequence voltage output terminals of the A-phase, B-phase, and C-phase circuits is interconnected to form an open triangle, which outputs a three-phase zero-sequence voltage signal. The phase-to-zero-sequence isolation transformer 11 can make the output phase-to-sequence and zero-sequence voltage signals linear across the entire measurement range, ensuring the accuracy of the circuit output results during use. It can also output the phase-to-sequence and zero-sequence voltage signals separately, preventing interference and impact between the signals. Furthermore, it enables independent operation of measurement and protection signals.

[0032] In this embodiment, the resistor-type straight-end phase zero-sequence integrated three-phase sensor for the ring network cabinet also includes a signal transmission component, which includes a primary high-voltage line cap 1, a primary high-voltage line 2, a secondary low-voltage line 5 and a circuit board 12. The primary high-voltage line cap 1 is sleeved on the primary high-voltage line 2 to protect the high-voltage line connector and prevent electrical faults and insulation damage. The input end of the primary high-voltage resistor 4 is connected to the power supply end through the primary high-voltage line 2; the input end of the secondary resistor 13 and the secondary capacitor 14 in parallel is connected to the output end of the primary high-voltage resistor 4 through the secondary low-voltage line 5; the secondary low-voltage part is installed on the circuit board 12 for easy installation.

[0033] In addition, the signal transmission assembly also includes a five-core shielded twisted pair cable 8, through which the output end of the secondary low-voltage section outputs a three-phase zero-sequence voltage signal. The five-core shielded twisted pair cable 8 twists five conductors together to reduce electromagnetic interference, ensuring that signals transmitted over a length range of 1.5 to 20 meters are not attenuated, maintaining signal integrity and clarity. Using the five-core shielded twisted pair cable 8 allows the phase sequence and zero-sequence voltages of the A-phase, B-phase, and C-phase circuits to be output simultaneously, reducing on-site wiring and facilitating installation.

[0034] In this embodiment, the resistor-type, straight-ended, phase-zero-sequence integrated three-phase sensor for a ring main unit also includes a mounting assembly comprising a stainless steel base 7, support studs 10, and mounting holes 9. The primary high-voltage resistor 4 is mounted on the stainless steel base 7; the circuit board 12 is mounted in the stainless steel base 7 via the support studs 10; and the three-phase sensor is connected to other equipment via the mounting holes 9.

[0035] The resistor-type, straight-end, phase-zero-sequence integrated three-phase sensor for a ring main unit also includes a sealing assembly comprising epoxy resin 3, a sealing ring 6, and a sealing silicone rubber 15. The epoxy resin 3 encapsulates the primary high-voltage resistor 4, forming an integral unit that is assembled on the stainless steel base 7. The secondary low-voltage portion is mounted within the stainless steel base 7, with the sealing silicone rubber 15 acting as an insulating material to fill the interior of the stainless steel base and seal the secondary low-voltage portion. The sealing ring 6 is mounted at the junction of the stainless steel base 7 and the primary high-voltage resistor 4, protecting the stainless steel base 7 from exposure to the sealing silicone rubber 15 while also providing a good seal.

[0036] In summary, the present invention utilizes the principle of resistor voltage division to output a stable voltage signal through the primary high-voltage part and the secondary low-voltage part, and can still provide a stable signal when a system fault such as single-phase grounding or phase loss occurs, and realizes three-phase voltage sampling, measurement, protection, phase sequence and zero sequence functions in one. In addition, the design of the three-phase sensor effectively avoids electromagnetic field interference and can output a small voltage signal that does not interfere with each other. Its functions and performance surpass the combination of three traditional phase sequence voltage transformers and three zero sequence voltage transformers, showing superior performance, including: operating temperature range: -40°C to +70°C; maximum operating voltage: 24kV; and small size, easy and quick installation, can operate for a long time at 1.9 times the rated voltage without destroying the existing design. It is particularly suitable for cabinets that have been put into use and can be easily installed in the existing space without modifying the original equipment or adding additional space. While saving costs, it is also very suitable for the intelligent transformation and upgrading of primary and secondary integrated ring network cabinet distribution equipment.

[0037] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A resistance-type straight-phase zero-sequence integrated three-phase sensor for ring network cabinet, characterized in that: It includes phase A, phase B and phase C circuits, and each phase circuit includes a primary high-voltage part and a secondary low-voltage part; The primary high-voltage part includes a primary high-voltage resistor, and the input end of the primary high-voltage resistor is connected to the power supply end; The secondary low-voltage part includes a secondary capacitor, a secondary resistor and a phase zero-sequence isolation transformer. The secondary capacitor and the secondary resistor are connected in parallel. The small voltage signal output after parallel connection is input into the phase zero-sequence isolation transformer, and two signals are output through the phase zero-sequence isolation transformer, including one phase sequence signal and one zero-sequence signal.

2. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 1, characterized in that: The primary high-voltage resistor is a columnar non-inductive high-precision thick film resistor.

3. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 1, characterized in that: The secondary low-voltage part further includes an inductor, which is connected in series with the phase zero-sequence isolation transformer.

4. The resistance-type straight-phase zero-sequence integrated three-phase sensor for a ring network cabinet according to claim 1, characterized in that: The secondary resistor includes a secondary low-voltage resistor and a secondary adjustable resistor connected in series.

5. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 1, characterized in that: The phase zero-sequence isolation transformer is provided with a phase-sequence voltage output terminal and a zero-sequence voltage output terminal. Each of the zero-sequence voltage output terminals of the A-phase, B-phase and C-phase circuits are interconnected to form an open triangle, and the open triangle outputs a three-phase zero-sequence voltage signal.

6. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 1, characterized in that: It also includes a signal transmission component; the signal transmission component includes a primary high-voltage line cap, a primary high-voltage line, a secondary low-voltage line and a circuit board; the primary high-voltage line cap is sleeved on the primary high-voltage line, and the input end of the primary high-voltage resistor is connected to the power supply end through the primary high-voltage line; the primary high-voltage part and the secondary low-voltage part are connected through the secondary low-voltage line; the secondary low-voltage part is installed on the circuit board.

7. The resistor-type straight-end phase zero-sequence integrated three-phase sensor for a ring main unit according to claim 6, characterized in that: The signal transmission component also includes a five-core shielded twisted pair cable; the output end of the secondary low-voltage part outputs a three-phase zero-sequence voltage signal through the five-core shielded twisted pair cable.

8. The resistor-type straight-phase zero-sequence integrated three-phase sensor for a ring main unit according to claim 6, characterized in that: It also includes an installation component; the installation component includes a stainless steel base, support studs and mounting holes; the primary high-voltage resistor is installed on the stainless steel base; the circuit board is installed in the stainless steel base through the support studs; and the three-phase sensor is connected to other equipment through the mounting holes.

9. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 8, characterized in that: It also includes a sealing component; the sealing component includes epoxy resin, a sealing ring and sealing silicone; the epoxy resin encapsulates the primary high-voltage resistor; the sealing silicone seals the secondary low-voltage part; the sealing ring is installed at the junction of the stainless steel base and the primary high-voltage resistor.

10. The resistance-type straight-end phase zero-sequence integrated three-phase sensor for ring network cabinet according to claim 1, characterized in that: The secondary capacitor is a monolithic secondary capacitor.

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