Testing device and method for simulating transformer winding turn-to-turn arc development process

Abstract

According to the testing device and method for simulating the development process of the transformer winding turn-to-turn arc, in the testing device, an insulating supporting column is arranged in an oil tank, a plurality of turns of coils are wound on the insulating supporting column to form a coil winding and are immersed in oil, and a divider resistor is connected between every two adjacent turns of coils in series; the high-voltage test transformer is connected with the coil to serve as a loop power supply to provide external voltage, the current-limiting resistor R0 is connected between the high-voltage test transformer and the coil, one end of the measuring resistor Rt is connected with the coil of the first turn, the other end of the measuring resistor Rt is grounded, and the measuring system measures and outputs the voltage of the two ends of the measuring resistor Rt and the voltage of each turn of coil.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, in particular to a test device and method for simulating the development process of inter-turn arcs in transformer windings. Background Art

[0002] Inter-turn discharges in transformer windings are often caused by winding deformation or inter-turn insulation defects. Generally, partial discharges develop into single-turn breakdowns and form arcs, and then the arcs rapidly develop from single-turn to multi-turn, with a sharp increase in discharge energy, which easily causes serious faults such as large-area burning of windings. The discharge location is usually at the head or end of the coil inside the winding, and the discharge is not easily detected and the initial signs are not obvious, making it difficult for transformer protection to respond in a timely manner. Therefore, it is necessary to conduct experimental simulations of the development process of inter-turn arcs in transformer windings to master the internal laws and external characteristics of their discharge development.

[0003] In the prior art, the simulation devices for internal discharge faults in transformers mainly use simple structures such as sharp tips and surface discharges, which are difficult to reflect the voltage characteristics and electric field distribution between turns of the winding, and are even less able to simulate the process of the arc developing from single-turn to multi-turn. If experiments are carried out using real transformer windings, on the one hand, the discharge development process is difficult to control and the repeatability is poor, and on the other hand, the cost is extremely high and the risk is relatively high.

[0004] The information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] A test device and method for simulating the development process of inter-turn arcs in transformer windings are provided to address the deficiencies or defects of the prior art. It can accurately simulate the development process of inter-turn arcs in transformer windings.

[0006] The object of the present invention is achieved through the following technical solutions.

[0007] A test device for simulating the development process of inter-turn arcs in transformer windings includes

[0008] An oil tank

[0009] Insulating supports provided in the oil tank

[0010] A multi-turn coil wound around the insulating supports to form a coil winding and immersed in oil, with a voltage-dividing resistor connected in series between every two adjacent turns of the coil

[0011] A high-voltage test transformer connected to the coil to provide an applied voltage as the loop power supply

[0012] A current-limiting resistor R0 connected between the high-voltage test transformer and the coil

[0013] Measure the resistance Rt, one end of which is connected to the coil of the first turn and the other end is grounded.

[0014] A measuring system that measures and outputs the voltages across both ends of the measured resistance Rt and each turn of the coil.

[0015] In the test device for simulating the development process of inter-turn arc in a transformer winding, the coil is wound with flat copper wire covered with insulating paper.

[0016] In the test device for simulating the development process of inter-turn arc in a transformer winding, the voltage-dividing resistor is a resistor with adjustable resistance.

[0017] In the test device for simulating the development process of inter-turn arc in a transformer winding, the voltage-dividing resistor and the current-limiting resistor are salt solution resistors, and the resistance value is adjusted by adjusting the solute concentration in the solution.

[0018] In the test device for simulating the development process of inter-turn arc in a transformer winding, the turn gap between two adjacent turns of the coil is adjustable.

[0019] In the test device for simulating the development process of inter-turn arc in a transformer winding, the multi-turn coil has 4 turns of coils, which are respectively denoted as the 1st, 2nd, 3rd, and 4th turns of coils from bottom to top. The 4 turns of coils form 3 turn gaps, and a voltage-dividing resistor is connected in series between every two turns, which are the voltage-dividing resistor R1, the voltage-dividing resistor R2, and the voltage-dividing resistor R3 from bottom to top.

[0020] In the test device for simulating the development process of inter-turn arc in a transformer winding, the voltages of the 3 turn gaps are proportional to the resistance values of the 3 voltage-dividing resistors. By adjusting the resistance values of the voltage-dividing resistor R1, the voltage-dividing resistor R2, and the voltage-dividing resistor R3, the magnitude of the inter-turn voltage is changed to simulate the actual working condition of uneven voltage distribution at the head or end of the transformer winding.

[0021] The simulation method of the test device for simulating the development process of inter-turn arc in a transformer winding includes simulating the development process of inter-turn arc discharge at the end of the winding. Adjust the resistance value of the voltage-dividing resistors so that the resistance values decrease sequentially from bottom to top. Introduce a defect between the second turn coil and the first turn coil, and keep the spacing of all turn gaps consistent. The high-voltage test transformer increases the voltage using the step-up method. When the applied voltage reaches the breakdown voltage, the turn gap between the second turn coil and the first turn coil breaks down first and forms a single-turn arc. At this time, the voltage-dividing resistor between the second turn coil and the first turn coil is short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors. Since the resistance values decrease sequentially from bottom to top, the voltages of the turn gaps from bottom to top decrease sequentially. The turn gap between the third turn coil and the second turn coil breaks down and forms a single-turn arc. At this time, the voltage-dividing resistor between the third turn coil and the second turn coil is also short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors, until the topmost voltage-dividing resistor is short-circuited, to simulate the discharge development process from single-turn arc to multi-turn arc under the condition of uneven voltage distribution at the end of the winding.

[0022] The described simulation method includes simulating the development process of inter-turn arc discharge at the beginning of the winding. Adjust the resistance value of the voltage-dividing resistors so that the resistance values increase sequentially from bottom to top. Introduce a defect between the last turn coil and the penultimate turn coil, and keep the spacing of all turn gaps consistent. The high-voltage test transformer increases the voltage using the step-up method. When the applied voltage reaches the breakdown voltage, the turn gap between the last turn coil and the penultimate turn coil breaks down first and forms a single-turn arc. At this time, the voltage-dividing resistor between the last turn coil and the penultimate turn coil is short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors. Since the resistance values increase sequentially from bottom to top, the voltages of the turn gaps from bottom to top increase sequentially. The turn gap between the third last turn coil and the penultimate turn coil breaks down and forms a single-turn arc. At this time, the voltage-dividing resistor between the third last turn coil and the penultimate turn coil is also short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors, until the bottommost voltage-dividing resistor is short-circuited, to simulate the discharge development process from single-turn arc to multi-turn arc under the condition of uneven voltage distribution at the beginning of the winding.

[0023] In the described simulation method, one end of the high-voltage test transformer is grounded.

[0024] Compared with the prior art, the beneficial effects brought by the present disclosure are: The present disclosure accurately simulates the development process of inter-turn arc discharge at the beginning and end of the winding and is convenient to adjust.

[0025] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to the extent that those skilled in the art can implement it according to the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, the following takes the specific implementation manners of the present invention as examples for illustration. Brief Description of the Drawings

[0026] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The accompanying drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. Moreover, throughout the drawings, the same reference numerals are used to denote the same components.

[0027] In the drawings:

[0028] Figure 1 is a schematic structural diagram of a test device for simulating the development process of inter-turn arc in a transformer winding provided by an embodiment of the present disclosure.

[0029] The present invention will be further explained below in conjunction with the drawings and embodiments. Detailed Description of the Preferred Embodiments

[0030] The specific embodiments of the present invention will be described in more detail below with reference to the drawings. Although the specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0031] It should be noted that certain terms are used in the specification and claims to refer to certain components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. The specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in function of components as the criterion for distinction. As used throughout the specification and claims, the term "comprising" or "including" is an open-ended term and should be interpreted as "including but not limited to". The subsequent description in the specification is for the purpose of describing the preferred embodiments of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the scope defined by the appended claims.

[0032] For the convenience of understanding the embodiments of the present invention, the following will further explain with several specific embodiments as examples in conjunction with the drawings, and each drawing does not constitute a limitation to the embodiments of the present invention.

[0033] For better understanding, as Figure 1 shown, a test device for simulating the development process of inter-turn arc in a transformer winding includes

[0034] Fuel tank

[0035] Insulating support, which is arranged in the fuel tank

[0036] Multi-turn coil, which is wound around the insulating support to form a coil winding and immersed in oil. A voltage-dividing resistor is connected in series between every two adjacent turns of the coil

[0037] High-voltage test transformer, which is connected to the coil to provide an applied voltage as a loop power supply

[0038] Current-limiting resistor R0, which is connected between the high-voltage test transformer and the coil

[0039] Measuring resistor Rt, one end of which is connected to the first turn of the coil and the other end is grounded

[0040] Measuring system, which measures and outputs the voltages at both ends of the measuring resistor Rt and each turn of the coil

[0041] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the coil is wound with flat copper wire covered with insulating paper

[0042] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the voltage-dividing resistor is a resistor with adjustable resistance

[0043] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the voltage-dividing resistor and the current-limiting resistor are salt solution resistors, and the resistance value is adjusted by adjusting the solute concentration in the solution

[0044] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the inter-turn gap between two adjacent turns of the coil is adjustable

[0045] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the multi-turn coil has 4 turns of coils, which are respectively denoted as the 1st, 2nd, 3rd, and 4th turns of coils from bottom to top. The 4 turns of coils form 3 inter-turn gaps, and a voltage-dividing resistor is connected in series between every two turns. From bottom to top, they are voltage-dividing resistor R1, voltage-dividing resistor R2, and voltage-dividing resistor R3

[0046] In a preferred embodiment of the test device for simulating the development process of inter-turn arc in a transformer winding, the voltages of the 3 inter-turn gaps are proportional to the resistance values of the 3 voltage-dividing resistors. By adjusting the resistance values of the voltage-dividing resistor R1, the voltage-dividing resistor R2, and the voltage-dividing resistor R3, the magnitude of the inter-turn voltage is changed to simulate the actual working condition of uneven voltage distribution at the head or end of the transformer winding

[0047] In one embodiment, the device includes a high-voltage test transformer, a current-limiting resistor R0, voltage-dividing resistors (R1, R2, R3), a coil, a measuring resistor Rt, an oil tank, insulating supports, a measuring system, etc. The high-voltage test transformer provides an applied voltage as the loop power supply. The function of R0 is to limit the magnitude of the loop current after breakdown to avoid exceeding the rated current. The winding model has a total of 4 turns of coils, which are respectively denoted as the 1st, 2nd, 3rd, and 4th turns from bottom to top. The coils are wound with flat copper wires covered with insulating paper, fixed on insulating supports and immersed in oil. The 4 turns of coils can form 3 turn gaps, and a voltage-dividing resistor is connected in series between every 2 turns, which are R1, R2, and R3 from bottom to top. According to the principle of series voltage division, the voltages of the 3 turn gaps are proportional to the resistances of the 3 voltage-dividing resistors. By adjusting the resistance values of R1 to R3, the magnitude of the turn-to-turn voltage can be changed to simulate the actual working condition of uneven voltage distribution at the head or end of the transformer winding. R1 to R3 use salt solution resistors, and the resistance value can be adjusted by adjusting the solute concentration in the solution. Defects are introduced into the turn gaps (damaging the coil insulation layer or adding metal particles) and the distances of the 3 turn gaps are adjusted to control the discharge starting position, turn-to-turn breakdown voltage, and the order of turn-to-turn breakdown. Rt is a measuring resistor used to measure the current in the loop and convert it into a voltage signal. The measuring system is used to measure and output the voltages across both ends of the measuring resistor Rt and each turn of the coil.

[0048] In one embodiment, the measuring system includes a voltage sensor.

[0049] The simulation method of the test device for simulating the development process of the turn-to-turn arc in the transformer winding includes simulating the development process of the turn-to-turn arc discharge at the end of the winding. Adjust the resistance values of the voltage-dividing resistors so that the resistance values decrease sequentially from bottom to top. Introduce defects between the 2nd turn coil and the 1st turn coil and keep the distances of all turn gaps consistent. The high-voltage test transformer uses the step-up voltage method to increase the voltage. When the applied voltage reaches the breakdown voltage, the turn gap between the 2nd turn coil and the 1st turn coil breaks down first and forms a single-turn arc. At this time, the voltage-dividing resistor between the 2nd turn coil and the 1st turn coil is short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors. Since the resistance values decrease sequentially from bottom to top, the voltages of the turn gaps from bottom to top decrease sequentially. The turn gap between the 3rd turn coil and the 2nd turn coil breaks down and forms a single-turn arc. At this time, the voltage-dividing resistor between the 3rd turn coil and the 2nd turn coil is also short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors until the topmost voltage-dividing resistor is short-circuited, so as to simulate the discharge development process from a single-turn arc to a multi-turn arc under the condition of uneven voltage distribution at the end of the winding.

[0050] The described simulation method includes simulating the development process of inter-turn arc discharge at the head end of the winding, adjusting the resistance value of the voltage-dividing resistors so that the resistance values increase sequentially from bottom to top, introducing a defect between the last turn of the coil and the penultimate turn of the coil, and keeping the spacing of all turn gaps consistent. The high-voltage test transformer uses the step-up voltage method to increase the voltage. When the applied voltage reaches the breakdown voltage, the turn gap between the last turn of the coil and the penultimate turn of the coil breaks down first and forms a single-turn arc. At this time, the voltage-dividing resistor between the last turn of the coil and the penultimate turn of the coil is short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors. Since the resistance values increase sequentially from bottom to top, the voltages of the turn gaps from bottom to top increase sequentially. The turn gap between the third-to-last turn of the coil and the penultimate turn of the coil breaks down and forms a single-turn arc. At this time, the voltage-dividing resistor between the third-to-last turn of the coil and the penultimate turn of the coil is also short-circuited, and the winding voltage is shared by the remaining voltage-dividing resistors until the bottommost voltage-dividing resistor is short-circuited, so as to simulate the discharge development process from a single-turn arc to a multi-turn arc under the condition of uneven distribution of the head-end voltage of the winding.

[0051] In a preferred embodiment of the simulation method, one end of the high-voltage test transformer is grounded.

[0052] In one embodiment, for the simulation of the development process of inter-turn arc discharge at the tail end of the winding, adjust the resistance values so that R1 > R2 > R3, introduce a defect between the 2nd and 1st turns, and keep the spacing of the 3 turn gaps consistent. Then operate the high-voltage test transformer and use the step-up voltage method to increase the voltage. When the applied voltage reaches the breakdown voltage, the 2-1 gap breaks down first and forms a single-turn arc. At this time, R1 is short-circuited, and the winding voltage is shared by R3 and R2. The voltages of the 4-3 and 3-2 turn gaps increase rapidly. Since R2 is greater than R3, the voltage of the 3-2 turn gap is significantly greater than that of the 4-3 gap. Therefore, the 3-2 gap breaks down and forms an arc. At this time, R2 is also short-circuited, and the winding voltage is borne by R3. The voltage of the 4-3 turn gap increases rapidly until it breaks down and forms an arc. The above steps can simulate the discharge development process from a single-turn arc to a multi-turn arc under the condition of uneven distribution of the tail-end voltage of the winding.

[0053] Simulation of the development process of inter-turn arc discharge at the winding head end: Adjust the resistance value so that R3 > R2 > R1, introduce a defect between the 4th and 3rd turns, and keep the spacing of the 3 turn gaps consistent. Then operate the high-voltage test transformer and increase the voltage using the step-up method. When the applied voltage reaches the breakdown voltage, the 4-3 gap breaks down first and forms a single-turn arc. At this time, R3 is short-circuited, and the winding voltage is shared by R2 and R1. The voltages of the 3-2 and 2-1 turn gaps increase rapidly. Since R2 is greater than R1, the voltage of the 3-2 turn gap is significantly greater than that of the 2-1 gap. Therefore, the 3-2 gap breaks down and forms an arc. At this time, R2 is also short-circuited, and the winding voltage is borne by R1. The voltage of the 2-1 turn gap increases rapidly until it breaks down and forms an arc. The above steps can simulate the discharge development process from a single-turn arc to a multi-turn arc under the condition of uneven voltage distribution at the winding head end.

[0054] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purposes of illustration and easy understanding, and not for limitation. The above details do not limit the present application to necessarily adopt the above specific details for implementation.

[0055] The above description has been given for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the form disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions, and sub-combinations thereof.

Claims

1. A test device for simulating the development process of inter-turn arcs in a transformer winding, characterized in that, It includes: an oil tank, an insulating support column disposed in the oil tank, a multi-turn coil wound around the insulating support column to form a coil winding and immersed in oil, and a voltage-dividing resistor is connected in series between every two adjacent turns of the coil, a high-voltage test transformer connected to the coil to provide an applied voltage as a loop power supply, a current-limiting resistor R0 connected between the high-voltage test transformer and the coil, a measuring resistor Rt, one end of which is connected to the first turn of the coil and the other end is grounded, a measuring system that measures and outputs the voltages at both ends of the measuring resistor Rt and each turn of the coil.

2. The test device for simulating the development process of inter-turn arc of a transformer winding according to claim 1, characterized in that, Preferably, the coil is wound with flat copper wire coated with insulating paper.

3. The test device for simulating the development process of inter-turn arc of a transformer winding according to claim 1, wherein, The voltage-dividing resistor is a resistor with adjustable resistance.

4. The test device for simulating the development process of the inter-turn arc of a transformer winding according to claim 1, characterized in that, The voltage-dividing resistor and the current-limiting resistor are salt solution resistors, and the resistance value is adjusted by adjusting the solute concentration in the solution.

5. The test device for simulating the development process of inter-turn arc of a transformer winding according to claim 1, wherein The turn gap between two adjacent turns of the coil is adjustable.

6. The test device for simulating the development process of inter-turn arc in a transformer winding according to claim 1, wherein The multi-turn coil has a total of 4 turns of coils, which are respectively denoted as the 1st, 2nd, 3rd, and 4th turns of coils from bottom to top. The 4 turns of coils form 3 turn gaps, and a voltage-dividing resistor is connected in series between every two turns. From bottom to top, they are voltage-dividing resistor R1, voltage-dividing resistor R2, and voltage-dividing resistor R3.

7. The test device for simulating the development process of inter-turn arc in a transformer winding according to claim 6, characterized in that, The voltages of the 3 turn gaps are proportional to the resistance values of the 3 voltage-dividing resistors. By adjusting the resistance values of the voltage-dividing resistor R1, the voltage-dividing resistor R2, and the voltage-dividing resistor R3, the magnitude of the turn voltage is changed to simulate the actual working condition of uneven voltage distribution at the head or end of the transformer winding.

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