Apparatus and method for performing an operating impulse test on a single-phase short-circuit test transformer

Abstract

The present application relates to the field of short-circuit test transformer, in particular to a device and method for implementing switching impulse test on single-phase short-circuit test transformer, the device comprises an intermediate three-phase power transformer T M ; during operation, a switching impulse voltage V0 is loaded to the second low-voltage winding of the transformer T M , so that the second high-voltage winding of the transformer T M generates an induced voltage V C between the first high-voltage winding of the single-phase short-circuit test transformer T T , the induced voltage V C = the specified switching impulse voltage V R of the transformer T T ; the first high-voltage winding of the induced voltage V C has a ground frequency voltage U0 AC at the first end and a ground frequency voltage U1 AC at the second end, the absolute values of the ground frequency voltage U0 AC at the first end and the ground frequency voltage U1 AC at the second end are both ≤ the power frequency withstand voltage UR T of the transformer T AC ; the device and method of the present application can avoid the damage of the single-phase short-circuit test transformer due to the ground frequency voltage loaded thereon being higher than the specified ground frequency withstand voltage during the switching impulse test.

Description

Technical Field

[0001] This invention relates to the field of short-circuit test transformers, and more specifically to an apparatus and method for performing operational impact tests on a single-phase short-circuit test transformer. Background Technology

[0002] For single-phase short-circuit test transformers in actual operation where the high-voltage side terminals are connected across different phases of the power grid (such as between phase A and phase B), the insulation levels required for the high-voltage side windings at the beginning and end are consistent. In this case, the specified operating impulse voltage level may be much higher than the corresponding voltage level specified in GB / T 1094.3, resulting in an equivalent power frequency voltage that is significantly higher than the required power frequency withstand voltage level.

[0003] For example, such as Figure 1 As shown, the fully insulated single-phase short-circuit test transformer with a rated voltage of 330kV on the high-voltage side has a specified power frequency withstand voltage to ground of 510kV for its high-voltage winding and a specified operating impulse voltage of 1425kV between its start and end terminals. The value of this operating impulse voltage, after being converted to power frequency voltage to ground, is 675kV (the conversion method is the industry-standard conversion formula: 1425÷2.11≈675, that is, the effect of a short-term continuous operating impulse voltage divided by 2.11 is equivalent to a 1-minute power frequency withstand voltage), which is much greater than the specified power frequency withstand voltage of 510kV for this single-phase short-circuit test transformer.

[0004] like Figure 1 As shown, when performing an operational impulse test on a single-phase short-circuit transformer using the traditional method (referring to the specifications in GB / T 1094.3), one end of the high-voltage winding is grounded, and the other end is subjected to a specified operational impulse voltage. However, as mentioned above, the operational impulse voltage between the beginning and end of the high-voltage winding, converted to a power frequency voltage to ground, far exceeds the transformer's specified power frequency withstand voltage. During the test, insulation breakdown of the high-voltage winding to ground (e.g., to the core column, upper and lower yokes) is highly likely, leading to the failure of the operational impulse test. If, during the design phase, the insulation strength of the winding ends to ground is enhanced by increasing the design distance and the number of insulating components to adapt to the traditional test method, the insulation design level of the transformer rises to a new level, significantly increasing costs and the product's transport height (due to the significantly increased distance from the coil to the upper and lower yokes), making transportation impossible. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide an apparatus and method for performing operational impulse tests on a single-phase short-circuit test transformer, which can prevent damage to the single-phase short-circuit test transformer during the operational impulse test due to the ground frequency voltage applied to it being higher than the specified ground frequency withstand voltage.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An apparatus for performing operational impulse tests on a single-phase short-circuit test transformer, comprising an intermediate three-phase power transformer T M Intermediate three-phase power transformer T M This includes a corresponding second high-voltage winding 3 and a second low-voltage winding 4; the single-phase short-circuit test transformer T T It includes a first high-voltage winding 1 and a first low-voltage winding 2 that are matched accordingly; the second high-voltage winding 3 is connected to the first high-voltage winding 1;

[0008] During operation, an operational impulse voltage V0 is applied to the second low-voltage winding 4, causing the second high-voltage winding 3 to generate an induced voltage V between the beginning and end of the first high-voltage winding 1. C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R Based on the induced voltage V C Calculate the voltage U0 between the first high-voltage winding 1 and ground. SI Voltage U1 at the tail end to ground SI The voltage U0 at the first end to ground SI Voltage U1 at the tail end to ground SI Converted to the power frequency voltage U0 at the beginning of the first high-voltage winding 1 and ground respectively AC The power frequency voltage U1 at the tail end to ground AC The first-end power frequency voltage U0 to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC And the power frequency voltage U1 at the tail end to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC .

[0009] Preferably, in the second high-voltage winding 3, the three-phase coils are connected in a star configuration. The first ends of any two phase coils are connected to form the second output terminal, and the first end of the other phase coil is the first output terminal. The first output terminal and the second output terminal are connected to the first end A and the last end X of the first high-voltage winding 1, respectively. The last ends of the three-phase coils of the second high-voltage winding 3 are connected and then grounded.

[0010] Preferably, in the second low-voltage winding 4, the three-phase coils are connected in a delta configuration. The first end of one phase coil is loaded with an operating impulse voltage V0 and the phase coil corresponds to the coil forming the first output terminal. The first end of one phase coil is left floating and the first end of one phase coil is grounded.

[0011] Preferably, in the second high-voltage winding 3, the first end of the U-phase coil is the first output end and is connected to the first end A of the first high-voltage winding 1. The first end of the V-phase coil and the first end of the W-phase coil are connected to form the second output end. The second output end is connected to the tail end X of the first high-voltage winding 1. The tail ends of the U-phase coil, the V-phase coil and the W-phase coil are connected and then grounded.

[0012] In the second low-voltage winding 4, the start end of the u-phase coil is loaded with an operating impulse voltage V0, the start end of the v-phase coil is left floating, and the start end of the w-phase coil is grounded.

[0013] Preferably, the rated phase voltage ratio between the second high-voltage winding 3 and the second low-voltage winding 4 is 10.

[0014] Preferably, the first end of the first low-voltage winding 2 is suspended and the last end is grounded.

[0015] Preferably, it further includes a power supply device and a test circuit for applying an operating impulse voltage V0 to the second low-voltage winding 4. The test circuit includes a first test lead, a second test lead, and a third test lead. The power supply device applies the operating impulse voltage V0 to the second low-voltage winding 4 through the third test lead, and the induced voltage V0 generated in the second high-voltage winding 3... C The first test conductor and the second test conductor are respectively applied between the start end A and the end X of the first high-voltage winding 1.

[0016] Preferably, the induced voltage V applied between the first high-voltage winding 1 and its end A and end X is... C This includes two induced electromotive forces in opposite directions generated by the second high-voltage winding 3 and transmitted through the first test conductor and the second test conductor, respectively.

[0017] Preferably, the induced voltage V C The ratio K to the operating impulse voltage V0 C0 Greater than the intermediate three-phase power transformer T M The rated phase voltage ratio K between the second high-voltage winding 3 and the second low-voltage winding 4.

[0018] Preferred, K C0 =1.5K.

[0019] A method for conducting an operational impulse test on a single-phase short-circuit test transformer, which is implemented using the aforementioned apparatus for conducting an operational impulse test on a single-phase short-circuit test transformer, includes the following steps:

[0020] Step 1: Connect the power supply equipment and the intermediate three-phase power transformer T in sequence. M and single-phase short-circuit test transformer T T ;

[0021] Step two, the power supply device applies an operating impulse voltage V0 to the second low-voltage winding 4, causing the second high-voltage winding 3 to generate an induced voltage V. C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R ;

[0022] Step 3, the induced voltage V C It is applied between the first high-voltage winding 1 and its end A and end X.

[0023] Preferably, the three-phase coils of the second high-voltage winding 3 are connected in a star configuration, with the first ends of any two phase coils connected to form the second output terminal, and the first end of the other phase coil being the first output terminal. The first output terminal and the second output terminal are connected to the first end A and the last end X of the first high-voltage winding 1, respectively. The last ends of the three-phase coils of the second high-voltage winding 3 are connected and grounded. The three-phase coils of the second low-voltage winding 4 are connected in a delta configuration, with an operating impulse voltage V0 applied to the first end of one phase coil, and this phase coil corresponding to the coil of the second high-voltage winding 3 that forms the first output terminal. The first end of one phase coil is left floating, and the first end of another phase coil is grounded. The first end of the first low-voltage winding 2 is left floating, and the last end is grounded.

[0024] Preferably, the intermediate three-phase power transformer T M It is a group-type power transformer, consisting of three single-phase power transformers. The low-voltage windings of the three single-phase power transformers are connected in a delta configuration, and the high-voltage windings of the three single-phase power transformers are connected in a star configuration.

[0025] The apparatus and method for performing operational impulse tests on single-phase short-circuit test transformers of the present invention, with the addition of a three-phase power transformer T M As an intermediate power source, the single-phase short-circuit test transformer T... T While withstanding the specified operating impulse voltage between the start and end points of the first high-voltage winding, the power frequency voltage U0 between the start point and ground of the first high-voltage winding is also... AC The power frequency voltage U1 at the end of the terminal is connected to ground. AC The absolute values ​​of all values ​​do not exceed the value of the single-phase short-circuit test transformer T. T Power frequency withstand voltage UR AC This ensured the success of the operational impact test and avoided single-phase short-circuit test transformer T T Because the power frequency voltage U0 at the first end to ground AC and / or terminal-to-ground power frequency voltage U1 AC The absolute value exceeds the power frequency withstand voltage UR AC The damage also simplifies the single-phase short-circuit test of transformer T. T The insulation design reduces its production cost and also helps control the single-phase short-circuit test transformer T.T This increases the transport altitude and improves its reliability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the principle of performing operational impact tests on a single-phase short-circuit test transformer using existing technology.

[0027] Figure 2 This is a schematic diagram of the device for performing operational impact tests on a single-phase short-circuit test transformer according to the present invention. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 2 The given embodiments further illustrate specific implementations of the apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to the present invention. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to the present invention is not limited to the descriptions in the following embodiments.

[0029] The apparatus of the present invention for performing operational impulse tests on a single-phase short-circuit test transformer includes an intermediate three-phase power transformer T. M Intermediate three-phase power transformer T M This includes a corresponding second high-voltage winding 3 and a second low-voltage winding 4; the single-phase short-circuit test transformer T T It includes a first high-voltage winding 1 and a first low-voltage winding 2 that are matched accordingly; the second high-voltage winding 3 is connected to the first high-voltage winding 1;

[0030] During operation, an operational impulse voltage V0 is applied to the second low-voltage winding 4, causing the second high-voltage winding 3 to generate an induced voltage V between the beginning and end of the first high-voltage winding 1. C Induced voltage V C =Specified operating impulse voltage V of single-phase short-circuit test transformer R Based on the induced voltage V C Calculate the voltage U0 between the first high-voltage winding 1 and ground. SI Voltage U1 at the tail end to ground SI The voltage U0 at the first end to ground SI Voltage U1 at the tail end to ground SI Converted to the power frequency voltage U0 at the first end of the first high-voltage winding 1 AC The power frequency voltage U1 at the tail end to ground AC Equivalent power frequency voltage U0 AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC And the power frequency voltage U1 at the tail end to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC .

[0031] The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer of the present invention adds a three-phase power transformer T M As an intermediate power source, the single-phase short-circuit test transformer T... T While withstanding the specified operating impulse voltage between the start and end points of the first high-voltage winding, the power frequency voltage U0 between the start point and ground of the first high-voltage winding is also... AC The power frequency voltage U1 at the end of the terminal is connected to ground. AC The absolute values ​​of all values ​​do not exceed the value of the single-phase short-circuit test transformer T. T Power frequency withstand voltage UR AC This ensured the success of the operational impact test and avoided single-phase short-circuit test transformer T T Because the power frequency voltage U0 at the first end to ground AC and / or terminal-to-ground power frequency voltage U1 AC The absolute value exceeds the power frequency withstand voltage UR AC The damage also simplifies the single-phase short-circuit test of transformer T. T The insulation design reduces its production cost and also helps control the single-phase short-circuit test transformer T. T This increases the transport altitude and improves its reliability.

[0032] Preferably, the apparatus for performing an operational impulse test on a single-phase short-circuit test transformer according to the present invention further includes a power supply device and a test circuit for applying an operational impulse voltage V0 to the second low-voltage winding 4. The test circuit includes a first test lead, a second test lead, and a third test lead. The power supply device applies the operational impulse voltage V0 to the second low-voltage winding 4 through the third test lead, and the induced voltage V0 generated in the second high-voltage winding 3... C The device of this invention employs a test circuit to connect the first test conductor to the first high-voltage winding 1 at its starting end A and its ending end X, respectively. This circuit enables the intermediate three-phase power transformer T to be tested. M Power supply equipment and single-phase short-circuit test transformer T T The electrical connection between them; the test circuit can have multiple schemes, a preferred scheme is as follows: Figure 2 As shown, it consists of three parts: the first part concerns the intermediate three-phase power transformer T. M The high-voltage side and single-phase short-circuit test transformer T T The second part concerns the circuit structure between the high-voltage sides; the third part concerns the intermediate three-phase power transformer T. M The circuit structure between the low-voltage side and the power supply equipment; the third part is about the single-phase short-circuit test transformer T. T Circuit structure on the low-voltage side.

[0033] The circuit structure of the first part is characterized by: including a first output terminal and a first test wire; the first output terminal is the first end of the U-phase coil of the second high-voltage winding 3, which is connected to the first end A of the first high-voltage winding 1 through the first test wire; the first end of the V-phase coil and the first end of the W-phase coil of the second high-voltage winding 3 are connected to form a second output terminal, which is connected to the tail end X of the first high-voltage winding 1 through the second test wire; the tail ends of the U-phase coil, the V-phase coil, and the W-phase coil are all grounded. The circuit structure of the second part includes an input terminal for loading the operating impulse voltage V0 and a third test wire; the first end of the U-phase coil and the tail end of the V-phase coil of the second low-voltage winding 4 form a loading input terminal, which is connected to the power supply equipment through the third test wire for loading the operating impulse voltage V0; the first end of the V-phase coil is connected to the tail end of the W-phase coil; the first end of the W-phase coil and the tail end of the U-phase coil are both grounded. The circuit structure of the third part: the first end a of the first low-voltage winding (2) is suspended, and the tail end x is grounded.

[0034] It should be noted that the above-mentioned grounding includes two equivalent connection structures. One is that the tail ends of the U-phase coil, V-phase coil, and W-phase coil are connected in parallel and then grounded; the other is that the tail ends of the U-phase coil, V-phase coil, and W-phase coil are grounded separately. Furthermore, the term "load input terminal" formed by the beginning of the U-phase coil and the tail end of the V-phase coil also includes two equivalent connection structures. One is that the beginning of the U-phase coil and the tail end of the V-phase coil are connected in parallel to form a common input terminal, which is connected to the power supply equipment through a third test lead; the other is that the beginning of the U-phase coil and the tail end of the V-phase coil each form an input terminal, and the two input terminals are connected to the power supply equipment separately through two third test leads. Of course, the U-phase coil and the U-phase coil must correspond (i.e., they are in phase), the V-phase coil and the V-phase coil must correspond, and the W-phase coil and the W-phase coil must correspond.

[0035] There are various specific implementation methods for the circuit structure in the first part, one preferred method is as follows: Figure 2 As shown, the characteristic is that: the three-phase coils (U, V, W) in the second high-voltage winding 3 of the test circuit adopt a star connection, wherein the first end of the U-phase coil is the first output terminal, the first end of the V-phase coil and the first end of the W-phase coil are connected to form the second output terminal, the first output terminal and the second output terminal are respectively connected to the first end A and the last end X of the first high-voltage winding 1 through the first test wire and the second test wire; the neutral point N formed by connecting the last ends of the three-phase coils (U, V, W) of the second high-voltage winding 3 is grounded.

[0036] There are various specific implementation methods for the circuit structure in the second part. One preferred method is as follows: Figure 2As shown, the three-phase coils (u, v, w) in the second low-voltage winding 4 of the test circuit are connected in a delta configuration. The node formed by connecting the beginning of the u-phase coil and the end of the v-phase coil is the load input terminal, which is connected to the power supply device through a third test wire to apply the operating impulse voltage V0. The beginning of the v-phase coil is connected to the end of the w-phase coil, and both the beginning of the w-phase coil and the end of the u-phase coil are grounded. This u-phase coil is in phase with the U-phase coil on the high-voltage side forming the first output terminal, and the node formed by connecting the end of the u-phase coil and the beginning of the connected w-phase coil is grounded.

[0037] Another important feature of the device of the present invention is that it employs a three-phase power transformer T from the middle. M For power supply equipment subjected to a low-voltage side loading impulse voltage V0, the beneficial effect is that the voltage level of the power supply equipment can be significantly reduced, such as... Figure 2 As shown: the phase voltage ratio K = 10, the K CO =1.5×10=15; when V C At 1425kV, the operating voltage of power supply equipment can be reduced by 15 times, and the operating impulse voltage V0 can be reduced to 95kV (i.e., 1425kV ÷ 15). For transformer manufacturers, configuring an intermediate three-phase power transformer T... M It is relatively easier and more economical than ordinary non-ultra-high voltage power supply equipment.

[0038] Another important feature of the device of this invention is the electrical structure formed by the above-mentioned features that differ from the prior art, including voltage, transformation, and induced electromotive force. It is known that in normal operation of a three-phase power transformer: in a delta connection, the phase voltage and line voltage are equal; in a star connection, the line voltage is equal to the phase voltage. The turns ratio of the three-phase transformer is equal to the rated phase voltage ratio K. When the three-phase high-voltage winding adopts a star connection, since the phase difference of the electromotive force induced by the three coils of the high-voltage winding is equal, it is impossible for the induced electromotive force of the two coils to always be in opposite directions.

[0039] like Figure 2 The image shows one embodiment of the device for performing operational impact tests on a single-phase short-circuit test transformer according to the present invention.

[0040] The apparatus of the present invention for performing operational impulse tests on a single-phase short-circuit test transformer includes an intermediate three-phase power transformer T. M Intermediate three-phase power transformer T M Including the second high-voltage winding 3 and the second low-voltage winding 4 in relative coordination, and the single-phase short-circuit test transformer T T This includes the first high-voltage winding 1 and the first low-voltage winding 2 that are matched accordingly.

[0041] The method of the present invention for performing an operational impulse test on a single-phase short-circuit test transformer is as follows: the second high-voltage winding 3 is connected to the first high-voltage winding 1, and an operational impulse voltage V0 is applied to the second low-voltage winding 4, causing the second high-voltage winding 3 to generate an induced voltage V. C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R , induced voltage V C Loaded between the beginning and end of the first high-voltage winding 1; based on the induced voltage V C Calculate the voltage U0 between the first high-voltage winding 1 and ground. SI Voltage U1 at the tail end to ground SI The voltage U0 at the first end to ground is respectively... SI Voltage U1 at the tail end to ground SI Converted to the power frequency voltage U0 at the beginning of the first high-voltage winding 1 to ground AC The power frequency voltage U1 at the tail end to ground AC The first-end power frequency voltage U0 to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC And the terminal-to-ground power frequency voltage U1 AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of the single-phase short T Power frequency withstand voltage UR AC Wherein, the operating impulse voltage V0 > 0, and the operating impulse voltage V is specified. R >0, power frequency withstand voltage UR AC >0, the rated phase voltage ratio between the second high-voltage winding 3 and the second low-voltage winding 4 is greater than 1.

[0042] Preferred, such as Figure 2 As shown, in the second high-voltage winding 3, its three-phase coils are connected in a star configuration. This star configuration means that the starting ends of any two phase coils are connected to form a second output terminal, and the starting end of the other phase coil is the first output terminal. The first and second output terminals are connected to the starting and ending ends of the first high-voltage winding 1, respectively. The ending ends of the three-phase coils of the second high-voltage winding 3 are connected and grounded. Further, as... Figure 2 As shown, in the second low-voltage winding 4, its three-phase coils are connected in a delta configuration. One phase coil has an operating impulse voltage V0 applied to its start end, and this phase coil corresponds to the coil forming the first output terminal. The start end of one phase coil is left floating, and the start end of another phase coil is grounded. It should be noted that the three-phase coils of the second low-voltage winding 4 can also be connected in a star configuration.

[0043] Preferably, the phase voltage ratio of the second high-voltage winding 3 and the second low-voltage winding 4 is 5-15. Further, the phase voltage ratio of the second high-voltage winding 3 and the second low-voltage winding 4 is 10.

[0044] Preferred, such as Figure 2 As shown, the single-phase short-circuit test transformer T T It also includes a first low-voltage winding 2 that corresponds to the first high-voltage winding 1, with its first end suspended and its last end grounded.

[0045] The apparatus for performing an operational impulse test on a single-phase short-circuit test transformer according to the present invention further includes a power supply device and a test circuit for applying an operational impulse voltage V0 to the second low-voltage winding 4. The test circuit includes a first test lead, a second test lead, and a third test lead. The power supply device applies the operational impulse voltage V0 to the second low-voltage winding 4 through the third test lead, and the induced voltage V0 generated in the second high-voltage winding 3... C A first test lead and a second test lead are respectively applied between the start end A and the end end X of the first high-voltage winding 1. Furthermore, an induced voltage V is applied between the start end A and the end end X of the first high-voltage winding 1. C This includes two induced electromotive forces in opposite directions generated by the second high-voltage winding 3 and transmitted through the first test conductor and the second test conductor, respectively.

[0046] Preferably, the induced voltage V C The ratio K to the operating impulse voltage V0 C0 Greater than the intermediate three-phase power transformer T M The rated phase voltage ratio K between the second high-voltage winding 3 and the second low-voltage winding 4. Further, the intermediate three-phase power transformer T... M The rated phase voltage ratio K between the second high-voltage winding 3 and the second low-voltage winding 4 is 10. C0 =1.5K. The K... C0 The transformer structure with a voltage greater than K is achieved by building a test circuit. In contrast, the actual phase voltage ratio of a known three-phase power transformer and its electrical connection structure is usually equal to the rated phase voltage ratio K (a constant given in the transformer inscription). Obviously, the structural features of this invention are different from those of the known technology. It not only makes a positive contribution to reducing the voltage level of the switching impulse voltage V0, but also makes a positive contribution to the overall safety of the switching impulse test.

[0047] like Figure 2 The image shows an embodiment of the apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to the present invention.

[0048] The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to the present invention includes a power supply device, a test circuit, and an intermediate three-phase power transformer T. MThe test circuit includes a first test lead, a second test lead, and a third test lead, with a three-phase power transformer T in the middle. M Including the corresponding high-voltage winding 3 and low-voltage winding 4, and the single-phase short-circuit test transformer T T Including the first high-voltage winding 1 and the first low-voltage winding 2 used in conjunction, the power supply equipment applies an operating impulse voltage V0 to the second low-voltage winding 4 through the third test lead, and the induced voltage V generated by the second high-voltage winding 3... C The first test conductor and the second test conductor are respectively applied between the start end A and the end X of the first high-voltage winding 1.

[0049] The phase voltage ratio of the second high-voltage winding 3 and the second high-voltage winding 4 is 10. In the second high-voltage winding 3, the U-phase coil, V-phase coil, and W-phase coil are connected in a star configuration. The first end of the U-phase coil is the first output terminal and is connected to the first end of the first high-voltage winding 1. The first end of the V-phase coil and the first end of the W-phase coil are connected to form the second output terminal, which is connected to the tail end of the first high-voltage winding 1. The tail ends of the U-phase coil, V-phase coil, and W-phase coil are connected and grounded. Alternatively, the first end of either the V-phase coil or the W-phase coil can be the first output terminal, and the first end of either the U-phase coil or the V-phase coil can be connected to form the second output terminal. In the second low-voltage winding 4, the u-phase coil, v-phase coil, and w-phase coil are connected in a delta configuration. This delta configuration involves applying an operational impulse voltage V0 to the beginning of the u-phase coil, leaving the beginning of the v-phase coil floating, and grounding the beginning of the w-phase coil. The beginning of the first low-voltage winding 2 is left floating, and its end is grounded. It should be noted that alternatively, the beginning of the v-phase coil can be applied with an operational impulse voltage V0, leaving the beginning of the w-phase coil floating, and grounding the beginning of the u-phase coil; or the beginning of the w-phase coil can be applied with an operational impulse voltage V0, leaving the beginning of the u-phase coil floating, and grounding the beginning of the v-phase coil.

[0050] Specifically, the voltage level of the first high-voltage winding 1 of the single-phase short-circuit test transformer is 330KV, and the specified power frequency withstand voltage UR ACThe voltage is 510kV, and the specified operating impulse voltage between the first and second ends is 1425kV. Since the first ends of the V-phase coil and the W-phase coil of the second high-voltage winding 3 are connected together, the magnetic flux directions of the V-phase and W-phase cores are opposite to those of the U-phase core, and their values ​​are half the value of the U-phase core flux. Therefore, the induced voltage between the first and second output ends is 1.5 times the induced voltage of the U-phase coil. If an operating impulse voltage of 1425kV is applied between the first and second ends of the first high-voltage winding 1, then an operating impulse voltage V0 = 1425 ÷ 1.5 ÷ 10 = 95kV needs to be applied to the first end of the U-phase coil of the second low-voltage winding 4, thus generating an induced voltage V0 between the first and second output ends of the second high-voltage winding 3. C =1425KV; at this time, the voltage between the first end of the first high-voltage winding 1 and ground is U0. SI =1425÷1.5=950KV, converted to the power frequency voltage U0 at the head end to ground AC ≈950÷2.1=450KV, power frequency voltage U0 at the first end to ground AC <Power frequency withstand voltage UR AC The voltage U1 at the tail end of the first high-voltage winding 1 to ground SI =U V =U W =-(950÷2)=-475KV, converted to the power frequency voltage U1 at the tail end to ground AC ≈-475÷2.11=-225KV, power frequency voltage U1 at the tail end to ground AC The absolute value is also less than the power frequency withstand voltage UR. AC .

[0051] This invention also discloses a method for conducting an operational impulse test on a single-phase short-circuit test transformer, which is implemented using the aforementioned apparatus for conducting an operational impulse test on a single-phase short-circuit test transformer, and includes the following steps:

[0052] Step 1: Connect the power supply equipment and the intermediate three-phase power transformer T in sequence. M and single-phase short-circuit test transformer T T ;

[0053] Step two, the power supply device applies an operating impulse voltage V0 to the second low-voltage winding 4, causing the second high-voltage winding 3 to generate an induced voltage V. C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R ;

[0054] Step 3, the induced voltage V C It is applied between the first high-voltage winding 1 and its end A and end X.

[0055] Preferably, the three-phase coils of the second high-voltage winding 3 are connected in a star configuration, with the first ends of any two phase coils connected to form the second output terminal, and the first end of the other phase coil being the first output terminal. The first output terminal and the second output terminal are connected to the first end A and the last end X of the first high-voltage winding 1, respectively. The last ends of the three-phase coils of the second high-voltage winding 3 are connected and grounded. The three-phase coils of the second low-voltage winding 4 are connected in a delta configuration, with an operating impulse voltage V0 applied to the first end of one phase coil, and this phase coil corresponding to the coil of the second high-voltage winding 3 that forms the first output terminal. The first end of one phase coil is left floating, and the first end of another phase coil is grounded. The first end of the first low-voltage winding 2 is left floating, and the last end is grounded.

[0056] Preferably, the intermediate three-phase power transformer T M It is a group-type power transformer, consisting of three single-phase power transformers. The low-voltage windings of the three single-phase power transformers are connected in a delta configuration, and the high-voltage windings of the three single-phase power transformers are connected in a star configuration.

[0057] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A device for performing operational impulse tests on a single-phase short-circuit test transformer, characterized in that, It includes the intermediate three-phase power transformer T M And power supply equipment, intermediate three-phase power transformer T M This includes a corresponding second high-voltage winding (3) and a second low-voltage winding (4); the power supply equipment is used to apply an operating impulse voltage V0 to the second low-voltage winding (4); the single-phase short-circuit test transformer T T It includes a first high-voltage winding (1) and a first low-voltage winding (2) that are matched accordingly; in the second high-voltage winding (3), its three-phase coils are connected in a star configuration, and the first ends of any two phase coils are connected to form the second output terminal, and the first end of the other phase coil is the first output terminal. The first output terminal and the second output terminal are connected to the first end A and the last end X of the first high-voltage winding (1) respectively, and the last ends of the three-phase coils of the second high-voltage winding (3) are connected and grounded; the first end of the first low-voltage winding (2) is left unconnected and the last end is grounded; During operation, an operational impulse voltage V0 is applied to the second low-voltage winding (4), causing the second high-voltage winding (3) to generate an induced voltage V between the beginning and end of the first high-voltage winding (1). C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R Based on the induced voltage V C Calculate the voltage U0 at the beginning of the first high-voltage winding (1) relative to ground. SI Voltage U1 at the tail end to ground SI The voltage U0 at the first end to ground SI Voltage U1 at the tail end to ground SI The voltage U0 at the beginning of the first high-voltage winding (1) relative to ground is converted respectively. AC The power frequency voltage U1 at the tail end to ground AC The first-end power frequency voltage U0 to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of ... single-phase short-circuit test transformer T. T Power frequency withstand voltage UR AC And the power frequency voltage U1 at the tail end to ground AC The absolute value of the single-phase short-circuit test transformer T is less than or equal to the absolute value of ... single-phase short-circuit test transformer T. T Power frequency withstand voltage UR AC .

2. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to claim 1, characterized in that: In the second low-voltage winding (4), its three-phase coils are connected in a delta configuration. The first end of one phase coil is loaded with an operating impulse voltage V0 and the phase coil corresponds to the coil forming the first output terminal. The first end of one phase coil is suspended and the first end of one phase coil is grounded.

3. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to claim 2, characterized in that: In the second high-voltage winding (3), the first end of the U-phase coil is the first output end and is connected to the first end A of the first high-voltage winding (1). The first end of the V-phase coil and the first end of the W-phase coil are connected to form the second output end. The second output end is connected to the tail end X of the first high-voltage winding (1). The tail ends of the U-phase coil, the V-phase coil and the W-phase coil are connected to the ground. In the second low-voltage winding (4), the first end of the u-phase coil is loaded with an operating impulse voltage V0, the first end of the v-phase coil is left floating, and the first end of the w-phase coil is grounded.

4. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to claim 2, characterized in that: The rated phase voltage ratio between the second high-voltage winding (3) and the second low-voltage winding (4) is 10.

5. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to claim 1, characterized in that: It also includes a test circuit, which includes a first test lead, a second test lead, and a third test lead. The power supply equipment applies an operating impulse voltage V0 to the second low-voltage winding (4) through the third test lead, and the second high-voltage winding (3) generates an induced voltage V. C The first test conductor and the second test conductor are respectively applied between the first high voltage winding (1) and the first high voltage winding (1) at the beginning A and the end X.

6. The apparatus for conducting an operational impulse test on a single-phase short-circuit test transformer according to claim 5, characterized in that: The induced voltage V applied between the first high-voltage winding (1) and its end A and end X C This includes two induced electromotive forces in opposite directions generated by the second high-voltage winding (3) and transmitted through the first test conductor and the second test conductor, respectively.

7. The apparatus for performing operational impulse tests on a single-phase short-circuit test transformer according to claim 5, characterized in that: The induced voltage V C The ratio K to the operating impulse voltage V0 C0 Greater than the intermediate three-phase power transformer T M The rated phase voltage ratio K between the second high voltage winding (3) and the second low voltage winding (4).

8. The apparatus for applying switching impulse voltage to a single-phase short-circuit test transformer according to claim 7, characterized in that: K C0 =1.5K。 9. A method for conducting an operational impulse test on a single-phase short-circuit test transformer, characterized in that, It is achieved by the apparatus for performing an operational impulse test on a single-phase short-circuit test transformer as described in any one of claims 1-8, which includes the following steps: Step 1: Connect the power supply equipment and the intermediate three-phase power transformer T in sequence. M and single-phase short-circuit test transformer T T ; Step two, the power supply device applies an operating impulse voltage V0 to the second low-voltage winding (4), causing the second high-voltage winding (3) to generate an induced voltage V. C Induced voltage V C =Single-phase short-circuit test transformer T T Specified operating impulse voltage V R ; Step 3, the induced voltage V C It is applied between the first end A and the last end X of the first high voltage winding (1).

10. The method for conducting an operational impulse test on a single-phase short-circuit test transformer according to claim 9, characterized in that: The three-phase coils of the second high-voltage winding (3) are connected in a star configuration. The first ends of any two phase coils are connected to form the second output terminal, and the first end of the other phase coil is the first output terminal. The first output terminal and the second output terminal are connected to the first end A and the last end X of the first high-voltage winding (1), respectively. The last ends of the three-phase coils of the second high-voltage winding (3) are connected and grounded. The three-phase coils of the second low-voltage winding (4) are connected in a delta configuration. The first end of one phase coil is loaded with an operating impulse voltage V0 and the phase coil corresponds to the coil of the second high-voltage winding (3) that forms the first output terminal. The first end of one phase coil is suspended and the first end of one phase coil is grounded. The first end of the first low-voltage winding (2) is suspended and the last end is grounded.

11. The method for conducting an operational impulse test on a single-phase short-circuit test transformer according to claim 9, characterized in that: The intermediate three-phase power transformer T M It is a group-type power transformer, consisting of three single-phase power transformers. The low-voltage windings of the three single-phase power transformers are connected in a delta configuration, and the high-voltage windings of the three single-phase power transformers are connected in a star configuration.

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