Three-phase integrated low-impedance voltage combination transformer with harmonic elimination function

Abstract

This invention discloses a three-phase integrated low-impedance voltage transformer with harmonic suppression function, relating to the field of three-phase combined voltage transformers. It includes four voltage transformers built into the transformer itself: three-phase voltage transformers A, B, and C, and a harmonic suppression transformer. Each of the three-phase voltage transformers A, B, and C has a primary winding coil and a secondary winding coil. The primary winding coil includes coil A, coil B, and coil C. Both the primary winding coil and the harmonic suppression transformer have a grounding terminal N. This invention integrates double-layer composite insulation, anti-resonance, and easy replacement functions, achieving miniaturization. This invention solves the technical problems of existing outdoor combined voltage transformers, such as large size, lack of built-in fuses for inconvenient replacement, aging and damage of insulation materials, three-phase imbalance, and susceptibility to resonance burnout.

Description

Technical Field

[0001] This invention relates to the field of three-phase combined voltage transformer technology, and specifically to a three-phase integrated low-impedance voltage combined transformer with harmonic suppression function. Background Technology

[0002] Currently, the three-phase combined voltage transformers in China are generally old-style oil-immersed insulated transformers and outdoor epoxy resin cast insulated transformers.

[0003] Oil-immersed insulated instrument transformers use insulating oil as the insulating medium, which is prone to oil leakage during use, requires frequent maintenance, and is inconvenient to maintain;

[0004] After several years of operation, outdoor epoxy resin insulation will be exposed to ultraviolet radiation, resulting in a dull surface, poor water repellency, uneven surface, and powdering in some areas, eventually leading to resin cracking.

[0005] Ordinary three-phase combined voltage transformers do not have anti-resonance function, nor can they suppress ultra-low frequency oscillation overcurrent. The product can only achieve the function of eliminating resonance and protecting the product through external harmonic suppressors and fuses, but the effect is not good.

[0006] Ordinary three-phase combined voltage transformers do not have harmonic suppression resistors, which can easily lead to three-phase imbalance during actual operation.

[0007] To address this issue, we provide a three-phase integrated low-impedance voltage transformer with harmonic suppression function. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a three-phase integrated low-impedance voltage transformer with harmonic suppression function. This solves the problem that conventional three-phase voltage transformers can only achieve harmonic suppression and product protection functions through external harmonic suppressors and fuses, and that the lack of harmonic suppression resistors easily leads to three-phase imbalance during actual product operation.

[0009] To achieve the above objectives, the present invention employs a three-phase integrated low-impedance voltage combined transformer with harmonic suppression function, comprising:

[0010] Four voltage transformers are built into the voltage transformer, specifically including: three-phase voltage transformers A, B, and C and a harmonic suppression transformer;

[0011] Among them, the three-phase voltage transformers A, B, and C have primary winding coils and secondary winding coils. The primary winding coils include coil A, coil B, and coil C. Both the primary winding coils and the harmonic suppression transformers have a grounding terminal N.

[0012] The A, B, and C three-phase voltage transformers also have primary terminals, and the harmonic suppression transformer has secondary terminals.

[0013] The primary terminal includes high-voltage terminal A, high-voltage terminal B and high-voltage terminal C. High-voltage terminal A, high-voltage terminal B and high-voltage terminal C are electrically connected. The three grounding terminals N of the primary winding coil are connected in series to the high-voltage terminal O of the harmonic suppression transformer. The other grounding terminal N of the harmonic suppression transformer is connected to the primary terminal for direct grounding.

[0014] The protection winding coils on the secondary side of the three-phase voltage transformers A, B, and C are connected in series end to end in an open delta configuration, with a harmonic suppression resistor connected in series between the openings of the open delta.

[0015] The ends of the secondary windings of the three-phase voltage transformers A, B, and C are connected in series to one terminal o of the harmonic suppression transformer, and the secondary terminal n of the harmonic suppression transformer is grounded.

[0016] As a further optimization of the above scheme, the voltage transformer internally adopts a 4PT structure consisting of three voltage transformer coils and one harmonic suppression transformer coil. The four voltage transformers are cast into a fully enclosed shell by epoxy resin, and an additional layer of silicone rubber insulation is added to the outside of the shell.

[0017] As a further optimization of the above solution, the specification of the harmonic elimination resistor is 3Ω 10W. An easy-to-maintain mounting slot is set at the bottom of the voltage transformer. The output end of the series-connected open delta is installed in the mounting slot of the voltage transformer. The output end of the series-connected open delta is hidden at the bottom of the voltage transformer and sealed with a stainless steel cover to prevent moisture.

[0018] The other winding of the harmonic-suppressing transformer has open delta secondary terminals da and dn connected to a relay or microcomputer monitoring system, and dn is grounded.

[0019] As a further optimization of the above solution, three high-voltage fuses are fixed on the housing by a detachable sleeve.

[0020] As a further optimization of the above solution, the primary terminal is equipped with a rainproof and insulating cap made of silicone rubber, and the secondary terminal is sealed with a secondary terminal sealing plate.

[0021] As a further optimization of the above scheme, the voltage transformer is mounted on a bracket made of channel steel, and the bracket has four lifting rings.

[0022] As a further optimization of the above solution, a cavity is provided inside the silicone rubber layer, and an elastomer and a magnetic sheet are disposed in the cavity. The magnetic sheet is fixedly connected to the upper surface of the elastomer. Both the upper surface of the magnetic sheet and the lower surface of the elastomer are fixed in the inner wall of the silicone rubber layer, and the magnetic sheet is located at the end of the elastomer away from the shell.

[0023] As a further optimization of the above scheme, multiple elastomers and magnetic sheets are provided in the cavity.

[0024] As a further optimization of the above solution, the silicone rubber layer is composed of blocks spliced ​​together, and adjacent silicone rubber layers are sealed and fixed with glue.

[0025] The three-phase integrated low-impedance voltage transformer with harmonic suppression function of the present invention has the following beneficial effects:

[0026] This invention discloses a three-phase integrated low-impedance voltage transformer with harmonic suppression function. This invention integrates double-layer composite insulation, anti-resonance, and convenient replacement functions, achieving miniaturization. This invention solves the technical problems of existing outdoor combined voltage transformers, such as large size, lack of built-in fuses for inconvenient replacement, aging and damage of insulation materials, three-phase imbalance, and susceptibility to resonance burnout.

[0027] Because the elastomer is placed inside the cavity, it is protected from rain, dust, ultraviolet rays, corrosion, etc., which increases its service life. Even if the silicone rubber layer ages due to external conditions, the elastomer can compensate for the overall protective ability of the silicone rubber layer.

[0028] It is composed of blocks spliced ​​together, and the adjacent silicone rubber layers are sealed and fixed with glue, which makes it easy to replace the silicone rubber layer individually, reducing the cost of use. It is especially suitable for situations where the silicone rubber layer in some areas of the external part of the voltage transformer is damaged.

[0029] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and that the embodiments of the present invention include many changes, modifications and equivalents within the spirit and scope of the appended claims. Attached Figure Description

[0030] Figure 1 This is a first-view sectional view of the three-phase integrated low-impedance voltage combined transformer with harmonic suppression function of the present invention.

[0031] Figure 2 This is a second-view sectional view of the three-phase integrated low-impedance voltage combined transformer with harmonic suppression function of the present invention.

[0032] Figure 3 This is a third-view sectional view of the three-phase integrated low-impedance voltage combined transformer with harmonic suppression function of the present invention.

[0033] Figure 4 This is a wiring diagram of the three-phase integrated low-impedance voltage combined transformer with harmonic suppression function of the present invention.

[0034] Figure 5 This is a schematic diagram of the internal structure of the silicone rubber layer of the present invention.

[0035] In the diagram: 1. High-voltage terminal A; 2. High-voltage terminal B; 3. High-voltage terminal C; 4. High-voltage terminal O; 5. Grounding terminal N; 6. Silicone rubber layer; 7. Housing; 8. High-voltage fuse; 9. Coil A; 10. Coil B; 11. Coil C; 12. Harmonic suppressor transformer; 13. Protective winding; 14. Harmonic suppressor resistor; 15. Secondary terminal sealing plate; 16. Rainproof insulating cap; 17. Bracket; 18. Lifting ring; 19. Cavity; 20. Elastomer; 21. Magnetic sheet. Detailed Implementation

[0036] Please refer to the instruction manual appendix. Figure 1-5 This invention provides a technical solution: a three-phase integrated low-impedance voltage combined transformer with harmonic suppression function, comprising:

[0037] The system has four built-in voltage transformer coils. The primary winding coils of the three-phase voltage transformers A, B, and C include coils A9, B10, and C11. One terminal of each of coils A9, B10, and C11 is electrically connected to the primary terminals of the three-phase voltage transformers A, B, and C via a high-voltage fuse 8. The primary terminals of the three-phase voltage transformers A, B, and C include high-voltage terminals A1, B2, and C3. The three grounding terminals N5 of the primary winding coils of the three-phase voltage transformers A, B, and C are connected in series to the high-voltage terminal O4 of the harmonic suppression transformer 12. The other grounding terminal N5 of the harmonic suppression transformer 12 is connected to the primary terminals for direct grounding.

[0038] The ends of the secondary winding coils of the three-phase voltage transformers A, B, and C are connected in series to one terminal o of the harmonic suppression transformer 12, and the secondary terminal n of the harmonic suppression transformer 12 is grounded; the other winding open delta secondary terminals da and dn of the harmonic suppression transformer 12 are connected to a relay or microcomputer monitoring, and dn is grounded.

[0039] The protection winding coils 13 on the secondary side of the three-phase voltage transformers A, B, and C are connected in series in an open delta configuration. A harmonic suppression resistor 14 is connected in series between the openings of the open delta. The harmonic suppression resistor 14 has a specification of 3Ω 10W. An easy-to-maintain mounting slot is provided at the bottom of the voltage transformer. The output end of the series-connected open delta is installed in the mounting slot of the voltage transformer. The output end of the series-connected open delta is hidden at the bottom of the voltage transformer and sealed with a stainless steel cover to prevent moisture.

[0040] The invention employs three voltage transformer coils and one harmonic suppression transformer coil internally, which are electrically connected to achieve the anti-resonance function. In addition, the internal 4PT structure is adopted to realize the anti-resonance function.

[0041] It should be noted that a 4PT consists of three single-phase fully insulated voltage transformers and one semi-insulated (or fully insulated) single-phase voltage transformer. During a ground fault, the primary voltage of the voltage transformer exhibits both zero-sequence and positive-sequence voltages. The positive-sequence voltage is applied to the main PT connected in a three-phase star configuration, while the zero-sequence voltage is borne by the three-phase main PT and the zero-sequence voltage transformer. Because the zero-sequence winding of the three-phase main PT is short-circuited, the zero-sequence impedance is very small, and almost all of it is applied to the zero-sequence voltage transformer, resulting in a voltage output on its secondary side and triggering a ground fault alarm.

[0042] The structure of 4PT specifically includes:

[0043] Single-phase fully insulated voltage transformer: This is a major component of the 4PT and is used to measure and convert voltage signals.

[0044] Semi-insulated or fully insulated single-phase voltage transformers: used to provide additional voltage measurement and protection functions during ground faults.

[0045] Impedance and reactor: used to suppress resonance and ensure stable operation of the system.

[0046] The main functions of 4PT include:

[0047] Voltage measurement: The voltage value of the system can be accurately measured by measuring the output of the voltage transformer.

[0048] Relay protection: When a ground fault occurs, the 4PT can respond quickly and issue an alarm signal, triggering the relay protection action.

[0049] Carrier communication: In neutral grounding systems, 4PT is also used for voltage measurement, power measurement, relay protection and carrier communication.

[0050] The present invention uses three high-voltage fuses 8 internally, which are fixed by detachable sleeves for easy replacement and effective protection of the transformer.

[0051] This invention not only has the function of preventing ferroresonance, but also has the unique function of suppressing ultra-low frequency oscillation overcurrent by improving the anti-saturation capability of the transformer core. The actual anti-saturation capability of the core is designed to be 2.28 times the rated voltage. This measure can effectively prevent the high-voltage winding of the voltage transformer from burning out, and in the resonant grounding system, it has the function of resisting various internal overvoltages. In addition, this invention also has a built-in high-voltage fuse 8 to prevent overcurrent in the system, thus giving the voltage transformer double protection.

[0052] In this invention, the protection winding coils 13 on the secondary side of the voltage transformer are connected in series in an open delta configuration. A harmonic suppression resistor is connected in series between the openings of the open delta. The output terminal of the open delta formed by the series connection is hidden at the bottom of the voltage transformer. By adding a harmonic suppression resistor, the phenomenon of three-phase voltage imbalance can be effectively prevented.

[0053] The four current transformers are enclosed in a shell 7 by epoxy resin casting. An additional layer of silicone rubber 6 is added to the outside of the shell 7 for insulation, achieving a double-layer composite insulation effect. Silicone rubber has good water repellency, which greatly improves the flashover voltage and can effectively prevent flashover faults. It also has anti-aging and tracking resistance properties, and can continuously withstand flashover voltage. Furthermore, it has strong resistance to mechanical shock, is not easily damaged, and has a long maintenance cycle.

[0054] This invention uses silicone rubber as the outer insulation, which features arc resistance, UV resistance, pollution resistance, and a long service life. Silicone rubber is also hydrophobic, allowing for long-term maintenance-free operation. A specially formulated epoxy resin is used as the inner insulation, effectively improving the product's low-temperature performance.

[0055] In this invention, the primary terminal of the voltage transformer is equipped with a rainproof insulating cap 16 made of silicone rubber, which can prevent rain, dust and oxidation of the primary terminal and poor contact.

[0056] The secondary terminals are sealed with a secondary terminal sealing plate 15, which can prevent rain, dust, corrosion, and electricity theft. The screws that fix the secondary terminal sealing plate 15 are all equipped with lead-sealed holes, which can be sealed with lead seals to prevent electricity theft caused by switching secondary lines. It is an ideal replacement product for power grid renovation and anti-electricity theft renovation.

[0057] In this invention, the voltage transformer is finally installed on a support 17 made of channel steel. The support 17 has four lifting rings 18 for hoisting.

[0058] This invention integrates double-layer composite insulation, anti-resonance, and easy replacement functions, achieving miniaturization of the product. This invention solves the technical problems of existing outdoor combined voltage transformers, such as large size, lack of built-in fuses for inconvenient replacement, aging and damage of insulation materials, three-phase imbalance, and susceptibility to resonance and burnout.

[0059] Furthermore, in this invention, the silicone rubber layer 6 has a cavity 19 inside, and a plurality of elastomers 20 and magnetic sheets 21 are disposed inside the cavity 19. The magnetic sheets 21 are fixedly connected to the upper surface of the elastomers 20. The upper surface of the magnetic sheets 21 and the lower surface of the elastomers 20 are both fixed in the inner wall of the silicone rubber layer 6, and the magnetic sheets 21 are located at the end of the elastomers 20 away from the shell 7. When the shell 7 is impacted, the hollow cavity 19 inside the silicone rubber layer 6 reduces the impact damage, and the elastomers 20 are compressed, increasing the recovery ability of the silicone rubber layer 6 and improving the overall buffering capacity of the silicone rubber layer 6.

[0060] Furthermore, since the elastomer 20 is located inside the cavity 19, it is protected from rain, dust, ultraviolet rays, corrosion, etc., and its service life will be relatively increased. Even if the silicone rubber layer 6 ages due to external conditions, the elastomer 20 can compensate for the overall protective ability of the silicone rubber layer 6.

[0061] In this invention, the magnetic sheet 21 can be adsorbed and fixed to the outside of the shell 7, and has the function of pressing the elastomer 20 and the silicone rubber layer 6 together, so that the silicone rubber layer 6 is further attached to the outside of the shell 7, and is not easy to detach or cause hollowing or delamination.

[0062] It should be noted that elastomer 20 can be made of TPE or thermoplastic polyurethane, which has better elastic properties than silicone rubber. The appropriate material can be selected according to actual needs, and no restrictions are imposed here.

[0063] In this invention, since the silicone rubber layer 6 is applied to the outside of the overall voltage transformer, it is composed of blocks spliced ​​together. Adjacent silicone rubber layers 6 are sealed and fixed with glue, which makes it convenient to replace individual parts of the silicone rubber layer 6, reducing the cost of use. It is especially suitable for situations where the silicone rubber layer 6 in some areas outside the voltage transformer is damaged.

[0064] It should be noted that, Figure 4 In this circuit diagram, Vbc represents the voltmeter measuring the secondary BC phase, vab represents the voltmeter measuring the secondary AB phase, vac represents the voltmeter measuring the secondary AC phase, "a", "b", and "c" represent the terminals a, b, and c of the secondary winding of the transformer, "Va" represents the voltmeter measuring the secondary a phase, "Vb" represents the voltmeter measuring the secondary b phase, "Vc" represents the voltmeter measuring the secondary c phase, and "R" represents the damping resistor of the da-dn circuit. This is a common circuit connection method and will not be elaborated upon here.

Claims

1. A three-phase integrated low-impedance voltage transformer with harmonic suppression function, characterized in that, include: Four voltage transformers are built into the voltage transformer, specifically including: A, B, C three-phase voltage transformers and harmonic suppression transformer (12); Among them, the three-phase voltage transformers A, B, and C have primary winding coils and secondary winding coils. The primary winding coils include coil A (9), coil B (10), and coil C (11). Both the primary winding coils and the harmonic elimination transformer (12) have grounding terminals N (5). The A, B, and C three-phase voltage transformers also have primary terminals, and the harmonic suppression transformer (12) has secondary terminals. The primary terminal includes high voltage terminal A (1), high voltage terminal B (2) and high voltage terminal C (3). High voltage terminal A (1), high voltage terminal B (2) and high voltage terminal C (3) are electrically connected. The three grounding terminals N (5) of the primary winding coil are connected in series to the high voltage terminal O (4) of the harmonic suppression transformer (12). The other grounding terminal N (5) of the harmonic suppression transformer (12) is connected to the primary terminal for direct grounding. The protection winding coils (13) on the secondary side of the three-phase voltage transformers A, B, and C are connected in series in an open delta configuration, and a harmonic suppression resistor (14) is connected in series between the openings of the open delta. The ends of the secondary winding coils of the three-phase voltage transformers A, B, and C are connected in series to one terminal o of the harmonic suppression transformer (12), and the secondary terminal n of the harmonic suppression transformer (12) is grounded.

2. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 1, characterized in that: The voltage transformer is internally composed of three voltage transformer coils and one harmonic suppression transformer coil to form a 4PT structure. The four voltage transformers are cast into a fully enclosed shell (7) by epoxy resin casting. A layer of silicone rubber (6) is added to the outside of the shell (7) for insulation.

3. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 1, characterized in that: The specifications of the harmonic elimination resistor (14) are 3Ω 10W. An easy-to-maintain mounting slot is set at the bottom of the voltage transformer. The output end of the series-connected open delta is installed in the mounting slot of the voltage transformer. The output end of the series-connected open delta is hidden at the bottom of the voltage transformer and sealed with a stainless steel cover to prevent moisture. The other winding of the harmonic-suppressing transformer (12) has open delta secondary terminals da and dn connected to a relay or microcomputer monitoring, and dn is grounded.

4. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 2, characterized in that: Three high-voltage fuses (8) are fixed to the housing (7) by a detachable sleeve.

5. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 1, characterized in that: The primary terminal is equipped with a rainproof insulating cap (16) made of silicone rubber, and the secondary terminal is sealed with a secondary terminal sealing plate (15).

6. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 1, characterized in that: The voltage transformer is mounted on a support (17) made of channel steel, and the support (17) has four lifting rings (18).

7. A three-phase integrated low-impedance voltage transformer with harmonic suppression function according to claim 1, characterized in that: The silicone rubber layer (6) has a cavity (19) inside, and an elastomer (20) and a magnetic sheet (21) are disposed in the cavity (19). The magnetic sheet (21) is fixedly connected to the upper surface of the elastomer (20). The upper surface of the magnetic sheet (21) and the lower surface of the elastomer (20) are both fixed in the inner wall of the silicone rubber layer (6), and the magnetic sheet (21) is located at the end of the elastomer (20) away from the shell (7).

8. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 7, characterized in that: The cavity (19) contains multiple elastomers (20) and magnetic sheets (21).

9. A three-phase integrated low-impedance voltage combined transformer with harmonic suppression function according to claim 1, characterized in that: The silicone rubber layer (6) is composed of blocks spliced ​​together, and adjacent silicone rubber layers (6) are sealed and fixed with glue.

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