External on-load tap changer device arranged independently of the transformer tank

Abstract

The application discloses an on-load voltage regulating switch device independent of transformer, and belongs to the technical field of power equipment. The device comprises an independently sealed on-load voltage regulator shell, an on-load voltage regulating switch arranged in the shell and an oil level meter mounted on the shell. The shell is provided with a high-voltage insulation sleeve and a transmission mechanism interface, and the bottom is provided with a connecting pipeline with a valve, which can selectively communicate or isolate with a transformer oil tank. The on-load voltage regulating switch is arranged separately from the transformer body, independent maintenance of the switch module is realized, arc pollutants generated by switch action are effectively isolated, pollution to the transformer main insulation oil is avoided, meanwhile, switch failure is limited in the independent cavity, and the operation reliability and safety of the transformer are remarkably improved. The application is compact in structure, convenient and safe and reliable in maintenance, and is suitable for on-load voltage regulating systems of various oil-immersed power transformers.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, and more particularly to an on-load tap changer for power transformers, especially an external on-load tap changer device that is installed independently of the transformer tank. Background Technology

[0002] In traditional oil-immersed power transformers, the on-load tap changer is typically installed directly inside the transformer tank, sharing the same tank as the transformer windings. While this built-in structure is more compact in terms of space utilization, it has revealed the following significant drawbacks in long-term operational practice:

[0003] 1. Difficulty in maintenance and repair: Because the on-load tap changer is encapsulated inside the transformer tank, when regular maintenance, contact replacement, or fault handling of the tap changer is required, a large amount of insulating oil inside the transformer body must first be drained. Then, the transformer body must be lifted out or maintenance personnel must enter the tank to operate. This process is complicated and time-consuming, usually requiring several days or even longer of power outage. Furthermore, frequent disassembly and assembly operations adversely affect the insulation system and sealing performance of the transformer body.

[0004] 2. Mutual Contamination Effects: On-load tap changers inevitably generate electric arcs when switching load currents. The high temperature of these arcs decomposes the insulating oil, producing free carbon particles and characteristic gases such as acetylene. In a built-in structure, these contaminants diffuse directly into the transformer's main insulating oil, gradually reducing the overall insulation performance of the transformer, accelerating insulation aging, and shortening the transformer's service life.

[0005] 3. Concentrated safety risks: If the voltage regulating switch malfunctions (such as contact burning, switching mechanism jamming, internal short circuit, etc.), the fault energy may directly cause a sudden increase in internal pressure of the transformer body, deformation of the oil tank, or even explosion, resulting in major equipment damage and personal safety hazards.

[0006] 4. Design constraints: In the built-in structure, the capacity and size of the voltage regulating switch are strictly limited by the space of the transformer tank, which is not conducive to the modular design and serial production of the switch, and it is also difficult to flexibly select different specifications of switches according to user needs.

[0007] Therefore, there is an urgent need in this field for a new type of on-load tap changer that can effectively isolate the tap changer from the transformer body, facilitate independent maintenance, and significantly improve operational reliability and safety. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the existing technology, such as maintenance difficulties, mutual contamination, concentrated safety risks and design limitations caused by the built-in installation of on-load tap changers, and to provide a modular, independently external on-load tap changer device that is easy to maintain and can effectively isolate faults.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] An on-load tap changer device independent of a transformer includes: a housing forming an independent, sealed cavity containing an insulating medium and core switch components; a high-voltage insulating bushing connected to the transformer's regulating winding leads on the housing, and a transmission mechanism interface for driving the switch operation; at least one on-load tap changer disposed inside the housing, the switch including a selector, a switching switch, and a corresponding contact system to change the turns ratio of the transformer winding under load current, thereby achieving a voltage regulation function; and an oil level gauge mounted on the housing for visually monitoring the liquid level of the insulating medium inside the housing; each of the on-load tap changers is connected in parallel with a branch circuit. The circuit is connected in series in the main control loop. The main control loop is equipped with a valve to enable selective linkage. The housing of the on-load tap changer is equipped with a high-voltage insulating bushing for connection to the transformer regulating winding and a transmission interface for connecting the drive mechanism. The bottom of the housing of the on-load tap changer is equipped with connecting pipes and valves for connection or isolation with the transformer tank. A mounting platform for the on-load tap changer is also installed. A power distribution control unit is installed on the side of the mounting platform. One end of the power distribution control unit is connected to the data monitoring equipment on the transformer, and the other end is connected to the on-load tap changer via a connecting circuit to control the opening and closing of the on-load tap changer and the load.

[0011] The housing is also equipped with one or more of the following: a pressure relief device, a gas relay, an oil injection / discharge valve, a sampling valve, and an online oil filter interface.

[0012] The oil level gauge is a temperature-compensated magnetic flip-type oil level gauge or a glass tube type oil level gauge, and is equipped with maximum and minimum oil level alarm contacts.

[0013] The drive motor and electrical control box of the on-load tap changer are independently located outside the housing.

[0014] The on-load tap changer housing is filled with an independent insulating medium, and its oil quality management is independent of the transformer main oil tank.

[0015] The technical problem to be solved by the present invention is to overcome the defects of the existing technology, such as maintenance difficulties, mutual contamination, concentrated safety risks and design limitations caused by the built-in installation of on-load tap changers, and to provide a modular, independently external on-load tap changer device that is easy to maintain and can effectively isolate faults.

[0016] The invention also relates to a transformer voltage regulation method, which uses an on-load tap changer independent of the transformer. The tap changer is connected in series in the main circuit, and the tap changer group is externally connected to the transformer casing. When the transformer voltage is at a risk value, the transformer voltage is regulated by externally adjusting the on-load tap changer group. At the same time, the tap changer includes one or at least two tap changers connected in parallel, so that when one tap changer fails, the opening and closing of the circuit valves in the parallel circuit can be used to switch the tap changers.

[0017] The beneficial effects of this invention are as follows:

[0018] Significantly improved ease of maintenance: The voltage regulating switch is an independent module. When it is repaired or replaced, there is no need to deal with the insulating oil of the transformer body. The operation can be carried out by simply isolating this device, which greatly shortens the power outage time and reduces maintenance costs and workload.

[0019] Significantly improved operational reliability: Effectively isolates the arc decomposition products generated by the operation of the voltage regulating switch, preventing them from contaminating the main insulating oil of the transformer, maintaining the insulation cleanliness of the transformer body, and improving the overall operational reliability and service life of the transformer.

[0020] Safety is significantly enhanced: Switch failures are effectively confined within an independent enclosure. Even in the event of a serious failure, the risks of explosions and fires are controlled to a localized area, greatly reducing the risk of the failure affecting the transformer itself and improving the safety level of equipment and personnel.

[0021] Enhanced design flexibility: The external design frees the selection of switch capacity and model from the strict limitations of transformer enclosure size, facilitating standardized and serialized production, and allowing users to flexibly select according to their actual needs.

[0022] Independent and precise condition monitoring: It can independently monitor the internal condition parameters of the device, such as oil level, oil quality, and gas content, to achieve more accurate fault warning and health management, and provide data support for condition-based maintenance. Attached Figure Description

[0023] Figure 1 This is a perspective view of the structure of the present invention;

[0024] Figure 2 This is a front view of the structure of the present invention;

[0025] Figure 3 This is a left view of the structure of the present invention;

[0026] Figure 4 This is a top view of the structure of the present invention;

[0027] 1- On-load tap changer housing; 2- Distribution control unit; 3- Oil level gauge; 4- High-voltage insulating bushing; 5- Connecting circuit; 6- Insulating oil pipeline and valve; 7- Pressure relief device; 8- Gas relay; 9- Transformer body. Detailed Implementation

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] Example 1

[0031] like Figure 1 As shown, the external on-load tap changer device provided by the present invention has a core of an independently sealed on-load tap changer housing 1. This housing is welded from high-strength steel plates, possessing good mechanical strength and sealing performance. It is filled with independent insulating oil and houses a complete on-load tap changer.

[0032] The leads of the transformer's regulating winding are connected to the interior of the casing via high-voltage insulating bushing 4, and reliably connected to the corresponding terminals of the on-load tap changer. The switching action of the switch is driven by an external motor through a transmission mechanism interface (such as a bevel gearbox or worm gear mechanism), realizing remote electric operation.

[0033] An oil level gauge 3 is installed in a prominent position on the side of the casing, allowing operators to clearly observe the internal insulating oil level remotely or locally. This embodiment uses a temperature-compensated magnetic flip-type level gauge and is equipped with maximum and minimum oil level alarm switches, which can automatically issue an alarm signal when the oil level is abnormal.

[0034] The bottom of the casing is equipped with an insulating oil pipe 6 with a valve, which can be selectively connected to the transformer oil tank. During normal operation, the valve can be closed, making this device independent of the transformer oil system; when oil sludge treatment is required, the valve can be opened to connect the two oil systems.

[0035] The top of the casing is also equipped with a pressure relief device 7 and a gas relay 8 for rapid pressure relief and protective tripping in case of internal faults. When a serious internal fault occurs in the switch causing a sudden pressure rise, the pressure relief device automatically opens to relieve pressure; the gas relay can issue a light gas alarm signal when characteristic gas is generated inside, or issue a heavy gas trip signal when oil flow surges.

[0036] When maintenance of the on-load tap changer is required, simply close the bottom pipeline valve 6, drain the insulating oil from the outer casing of the device, and then open the maintenance port or end cover on the casing to inspect, repair, or replace the internal switch. The entire process does not affect the operating status of the transformer body 9 at all, significantly shortening the power outage time.

[0037] During operation, an oil level gauge 3 is prominently installed on the side of the casing, allowing operators to clearly observe the internal insulating oil level remotely or locally. The bottom of the casing can be selectively connected to or isolated from the transformer tank via an insulating oil pipe 6 equipped with a valve. A pressure relief device 7 and a gas relay 8 are also installed on the top of the casing for rapid pressure relief and protective tripping in case of internal faults.

[0038] When the voltage regulating switch needs to be inspected, close the bottom pipeline valve 6, drain the insulating oil inside the outer casing of the device, and then open the maintenance hole or end cover to work on the internal switch 2. The whole process does not affect the transformer body at all.

[0039] The invention also relates to a transformer voltage regulation method, which uses an on-load tap changer independent of the transformer. The tap changer is connected in series in the main circuit, and the tap changer group is externally connected to the transformer casing. When the transformer voltage is at a risk value, the transformer voltage is regulated by externally adjusting the on-load tap changer group. At the same time, the tap changer includes one or at least two tap changers connected in parallel, so that when one tap changer fails, the opening and closing of the circuit valves in the parallel circuit can be used to switch the tap changers.

[0040] The diagram only shows one set. In actual operation, multiple on-load tap changers can be mounted on the bracket where the on-load tap changer housing is located. The on-load tap changers are connected by parallel circuits, and each branch is equipped with a quick-connect valve.

[0041] Example 2

[0042] As another implementation, the drive motor and electrical control box of the on-load tap changer can be independently installed outside the housing and connected to the switch via a transmission mechanism. This arrangement further achieves physical isolation between the electrical components and the oil chamber, improving electrical safety and ease of maintenance.

[0043] The outer casing can also be equipped with an oil injection / drain valve, a sampling valve, and an online oil filter interface, which facilitates regular sampling and testing of the insulating oil inside the device and online purification treatment, enabling refined condition maintenance.

[0044] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An on-load tap changer independent of a transformer, characterized in that, include: The outer casing forms an independent, sealed cavity containing the insulating medium and the core switch components. The casing is equipped with a high-voltage insulating bushing connected to the transformer's regulating winding leads, and an interface for a transmission mechanism to drive the switch. It also includes at least one on-load tap changer located inside the casing, comprising a selector, a switching switch, and a corresponding contact system to change the turns ratio of the transformer winding under load current, thus achieving voltage regulation. Furthermore, it includes an oil level gauge mounted on the casing for visually monitoring the liquid level of the insulating medium inside the casing. All the on-load tap changers are connected in parallel branches in series in the main control circuit. On the route, the main control recovery is equipped with a valve to achieve selective linkage; the housing of the on-load tap changer is equipped with a high-voltage insulating bushing connected to the transformer regulating winding and a transmission interface for connecting the drive mechanism; the bottom of the housing of the on-load tap changer is equipped with connecting pipes and valves to achieve connection or isolation with the transformer tank; a mounting platform for the on-load tap changer device is also installed, and a power distribution control unit is installed on the side of the mounting platform. One end of the power distribution control unit is connected to the data monitoring equipment on the transformer, and the other end is connected to the on-load tap changer device via a connecting circuit to control the opening and closing of the on-load tap changer device and the load.

2. The on-load tap changer device independent of the transformer according to claim 1, characterized in that, The housing is also equipped with one or more of the following: a pressure relief device, a gas relay, an oil injection / discharge valve, a sampling valve, and an online oil filter interface.

3. The on-load tap changer device independent of the transformer according to claim 1, characterized in that, The oil level gauge is a temperature-compensated magnetic flip-type oil level gauge or a glass tube type oil level gauge, and is equipped with maximum and minimum oil level alarm contacts.

4. The on-load tap changer device independent of the transformer according to claim 1, characterized in that, The drive motor and electrical control box of the on-load tap changer are independently located outside the housing.

5. The on-load tap changer device independent of the transformer according to claim 1, characterized in that, The on-load tap changer housing is filled with an independent insulating medium, and its oil quality management is independent of the transformer main oil tank.

6. A transformer voltage regulation method, using an on-load tap changer device independent of the transformer as described in claim 1, characterized in that: The main circuit is connected in series with a voltage regulating switch assembly, which is externally connected to the transformer housing. When the transformer voltage is at a risk value, the transformer voltage can be regulated by externally adjusting the on-load tap changer assembly. At the same time, the voltage regulating switch assembly includes one or at least two parallel voltage regulating switches, so that when one voltage regulating switch fails, the circuit valves on the parallel circuit can be used to switch on and off and replace the voltage regulating switches.

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